Ultra Clean (UCTT) 10-Q 1 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 23, 2016	Oct. 28, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 23, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	UCTT
Entity Registrant Name	Ultra Clean Holdings, Inc.
Entity Central Index Key	1,275,014
Current Fiscal Year End Date	--12-30
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		32,922,211

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Current assets:
Cash and cash equivalents	$ 47,270	$ 50,103
Accounts receivable, net of allowance of $42 and $158, respectively	65,805	59,148
Inventories	89,015	72,716
Prepaid expenses and other	6,941	8,172
Total current assets	209,031	190,139
Equipment and leasehold improvements, net	18,809	17,267
Goodwill	85,248	85,248
Purchased intangibles, net	38,464	42,782
Other non-current assets	743	717
Total assets	352,295	336,153
Current liabilities:
Bank borrowings	15,196	12,744
Accounts payable	51,954	39,660
Accrued compensation and related benefits	6,992	6,536
Deferred rent, current portion	673	584
Other current liabilities	10,208	5,187
Total current liabilities	85,023	64,711
Bank borrowings, net of current portion	54,023	62,795
Deferred tax liability	5,797	4,519
Deferred rent and other liabilities	2,547	3,185
Total liabilities	147,390	135,210
Commitments and contingencies (See Note 9)
Stockholders’ equity:
Preferred stock — $0.001 par value, 10,000,000 authorized; none outstanding
Common stock — $0.001 par value, 90,000,000 authorized; 32,912,546 and 32,279,429 shares issued and outstanding in 2016 and 2015, respectively	33	32
Additional paid-in capital	180,048	176,280
Common shares held in treasury, at cost, 601,944 shares in 2016 and 2015	(3,337)	(3,337)
Retained earnings	28,084	27,986
Accumulated other comprehensive income (loss)	77	(18)
Total stockholders’ equity	204,905	200,943
Total liabilities and stockholders’ equity	$ 352,295	$ 336,153

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Statement Of Financial Position [Abstract]
Account receivable, allowance	$ 42	$ 158
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	32,912,546	32,279,429
Common stock, shares outstanding	32,912,546	32,279,429
Treasury stock, shares	601,944	601,944

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Income Statement [Abstract]
Sales	$ 146,154	$ 122,816	$ 388,214	$ 365,683
Cost of goods sold	122,663	103,868	331,132	307,994
Gross profit	23,491	18,948	57,082	57,689
Operating expenses:
Research and development	2,447	2,352	7,082	7,319
Sales and marketing	2,819	2,844	8,537	8,494
General and administrative	11,525	10,673	31,742	32,721
Total operating expenses	16,791	15,869	47,361	48,534
Income from operations	6,700	3,079	9,721	9,155
Interest and other income (expense), net	(1,336)	(756)	(3,263)	(2,071)
Income before provision for income taxes	5,364	2,323	6,458	7,084
Income tax provision	2,750	647	6,360	2,028
Net income	$ 2,614	$ 1,676	$ 98	$ 5,056
Net income per share:
Basic	$ 0.08	$ 0.05	$ 0	$ 0.16
Diluted	$ 0.08	$ 0.05	$ 0	$ 0.16
Shares used in computing net income per share:
Basic	32,759	31,993	32,544	31,359
Diluted	33,100	32,155	32,887	31,653

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 2,614	$ 1,676	$ 98	$ 5,056
Other comprehensive income (loss):
Change in cumulative translation adjustment	50	67	125	67
Cash flow hedges:
Change in fair value of derivatives	27	(91)	(101)	(91)
Adjustment for net loss realized and included in net income	20	4	71	4
Total change in unrealized loss on derivative instruments	47	(87)	(30)	(87)
Other comprehensive income (loss):	97	(20)	95	(20)
Comprehensive income	$ 2,711	$ 1,656	$ 193	$ 5,036

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows $ in Thousands	9 Months Ended
	Sep. 23, 2016USD ($)	Sep. 25, 2015USD ($)
Cash flows from operating activities:
Net income	$ 98	$ 5,056
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,242	3,447
Amortization of finite-lived intangibles	4,318	4,042
Amortization of debt issuance costs	114	790
Stock-based compensation	4,040	2,607
Change in the fair value of the contingent earn out	1,405
Excess tax benefit from stock-based compensation	771	809
Changes in assets and liabilities, net of effects of acquisition:
Accounts receivable	(6,567)	7,416
Inventory	(16,185)	(11,071)
Prepaid expenses and other	1,249	(1,300)
Deferred income taxes	1,276	(196)
Other non-current assets	(26)	(12)
Accounts payable	12,342	(8,180)
Accrued compensation and related benefits	443	132
Income taxes payable	450	(809)
Other liabilities	1,412	1,712
Net cash provided by operating activities	9,382	4,443
Cash flows from investing activities:
Purchases of equipment and leasehold improvements	(5,460)	(5,196)
Disposal of equipment and leasehold improvements	34
Acquisition of business		(44,495)
Net cash used for investing activities	(5,426)	(49,691)
Cash flows from financing activities:
Proceeds from bank borrowings	4,523	76,981
Proceeds from issuance of common stock	500	2,307
Principal payments on bank borrowings	(11,016)	(51,509)
Payments of debt issuance costs		(611)
Excess tax benefit from stock-based compensation	(771)	(809)
Employees’ taxes paid upon vesting of restricted stock units		(331)
Net cash provided by (used for) financing activities	(6,764)	26,028
Effect of exchange rate changes on cash and cash equivalents	(25)	6
Net decrease in cash and cash equivalents	(2,833)	(19,214)
Cash and cash equivalents at beginning of period	50,103	78,997
Cash and cash equivalents at end of period	47,270	59,783
Supplemental cash flow information:
Income taxes paid	2,988	2,611
Income tax refunds	591
Interest paid	1,920	1,776
Non-cash investing activities:
Fair value of common shares issued for acquisition		17,661
Fair value of earn-out payments related to Miconex acquisition		1,280
Equipment and leasehold improvements purchased included in accounts payable	$ 483	$ 3,531

Organization and Significant Ac

Organization and Significant Accounting Policies	9 Months Ended
	Sep. 23, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Significant Accounting Policies	1. Organization and Significant Accounting Policies Organization — Ultra Clean Holdings, Inc. (the “Company” or “UCT”) was founded in November 2002 for the purpose of acquiring Ultra Clean Technology Systems and Service Inc. Ultra Clean Technology Systems and Service, Inc. was founded in 1991 by Mitsubishi Corporation and was operated as a subsidiary of Mitsubishi until November 2002, when it was acquired by UCT. UCT became a publicly traded company in March 2004. In June 2006, the Company completed the acquisition of Sieger Engineering, Inc. to enhance its position as a subsystem supplier to the semiconductor, research, flat panel, energy and medical equipment industries. Ultra Clean Technology (Shanghai) Co., Ltd (“UCTS”) and Ultra Clean Micro-Electronics Equipment (Shanghai) Co., Ltd. (“UCME”) were established in 2005 and 2007, respectively, to facilitate the Company’s operations in China. In December 2015, UCTS merged into UCME. Ultra Clean Asia Pacific, Pte, Ltd. (Singapore) (“UCAP”) was established in fiscal year 2008 to facilitate the Company’s operations in Singapore. In July 2012, UCT acquired American Integration Technologies LLC (“AIT”) to add to the Company’s existing customer base in the semiconductor and medical spaces and to provide additional manufacturing capabilities. In November 2014, the Company launched Prototype Asia, its 3D printing business in Singapore, to develop additive manufacturing capabilities for the Company’s customer base. In February 2015, UCT acquired Marchi Thermal Systems, Inc. (“Marchi”), a designer and manufacturer of specialty heaters, thermocouples and temperature controllers. Marchi delivers flexible heating elements and thermal solutions to UCT’s customers. The Company believes heaters are increasingly critical in equipment design for the most advanced semiconductor nodes. In July 2015, UCT acquired MICONEX s.r.o. (“Miconex”), a privately-held provider of advanced precision fabrication of plastics, primarily for the semiconductor industry that expanded the Company’s capabilities with existing customers. The Company is a global leader in the design, engineering, and manufacture of production tools, modules and subsystems for the semiconductor capital equipment and equipment industry segments with similar requirements including consumer, medical and flat panel display. The Company focuses on providing specialized engineering and manufacturing solutions for these highly complex, highly configurable, limited volume applications. The Company enables its customers to realize lower manufacturing costs and reduced design-to-delivery cycle times while maintaining high quality standards. The Company provides its customers with complete solutions that combine its expertise in design, assembly, test and component characterization. The Company’s customers value its highly flexible global manufacturing operations, its excellence in quality control and its scale and financial stability. The Company’s global footprint enables the Company to reduce manufacturing costs and design-to-delivery cycle times while maintaining high quality standards for the Company’s customers. The Company believes that these characteristics allow the Company to provide global solutions for its customers’ product demands. The Company ships the majority of its products to U.S. registered customers with locations both in and outside the U.S. In addition to its U.S. manufacturing capabilities, the Company manufactures products in its Asian facilities to support local and U.S. based customers. The Company conducts its operating activities primarily through its wholly-owned subsidiaries, Ultra Clean Technology Systems and Service, Inc., AIT, UCTS, UCME, UCAP, Marchi and Miconex. The Company’s international sales represented 49.7% and 35.6% of total sales for the three months ended September 23, 2016 and September 25, 2015, respectively, and 46.5% and 33.3% of total sales for the nine months ended September 23, 2016 and September 25, 2015, respectively. See Note 10 to the Company’s Condensed Consolidated Financial Statements for further information about the Company’s geographic areas. Basis of Presentation — The unaudited condensed consolidated financial statements included in this quarterly report on Form 10-Q include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). This financial information reflects all adjustments which are, in the opinion of the Company, normal, recurring and necessary for the fair financial statement presentation for the dates and periods presented. Certain information and footnote disclosures normally included in our annual financial statements, prepared in accordance with GAAP, have been condensed or omitted. The Company’s December 25, 2015 balance sheet data were derived from its audited financial statements as of that date. Principles of Consolidation — The Company’s condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and all intercompany accounts and transactions have been eliminated in consolidation. The Company uses a 52-53 week fiscal year ending on the Friday nearest December 31. All references to quarters refer to fiscal quarters and all references to years refer to fiscal years. Foreign Currency Translation and Remeasurement — The Company has one foreign subsidiary whose functional currency is not its local currency or the U.S. dollar. The Company remeasures the monetary assets and liabilities of this subsidiary into its functional currency. Gains and losses from these remeasurements are recorded in interest and other income (expense), net. The Company then translates the assets and liabilities of this subsidiary into the U.S. dollar. Gains and losses from these translations are recognized in foreign currency translation included in accumulated other comprehensive income (AOCI) within stockholders’ equity. For the Company’s foreign subsidiaries where the U.S. dollar is the functional currency, any gains and losses resulting from the remeasurement of the assets and liabilities of these subsidiaries are recorded in interest and other income (expense), net. Use of Accounting Estimates — The presentation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Such estimates and assumptions include reserves on inventory, valuation of deferred tax assets and impairment of goodwill and other long-lived assets. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, future events are subject to change and the best estimates and judgments routinely require adjustment. Actual amounts may differ from those estimates. Concentration of Credit Risk — Financial instruments which subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable. The Company sells its products primarily to semiconductor capital equipment manufacturers in the United States. The Company performs credit evaluations of its customers’ financial condition and generally requires no collateral. Significant Sales to Customers — The Company’s most significant customers (having accounted for 10% or more of sales) and their related sales as a percentage of total sales were as follows: Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Lam Research Corporation 49.5 % 49.4 % 53.5 % 50.4 % Applied Materials, Inc. 30.9 26.4 27.3 27.1 Total 80.4 % 75.8 % 80.8 % 77.5 % Two customers’ accounts receivable balances, Lam Research Corporation and Applied Materials, Inc., were individually greater than 10% of accounts receivable as of September 23, 2016 and three customers’ accounts receivable balances, Lam Research Corporation, Applied Materials, Inc. and ASM International, Inc., were individually greater than 10% of accounts receivable as of December 25, 2015, and in the aggregate represented approximately 77.9% and 84.6% of accounts receivable as of September 23, 2016 and December 25, 2015, respectively. Fair Value of Measurements — The Company measures its cash equivalents, interest rate derivative contracts and contingent earn-out liability at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that is determined based on assumptions that market participants would use in pricing an asset or a liability. Assets and liabilities recorded at fair value are measured and classified in accordance with a three-tier fair value hierarchy based on the observability of the inputs available in the market used to measure fair value: Level 1 — Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2 — Inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, foreign exchange rates, and credit ratings. Level 3 — Unobservable inputs that are supported by little or no market activities. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The following table summarizes, for assets or liabilities measured at fair value, the respective fair value and the classification by level of input within the fair value hierarchy (in thousands): Fair Value Measurement at Reporting Date Using Description September 23, 2016 Quoted Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other liabilities: Interest rate swap $ 56 $ — $ 56 $ — Contingent earn-out liability $ 2,236 $ — $ — $ 2,236 Fair Value Measurement at Reporting Date Using Description December 25, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash and cash equivalents: Money market fund deposits $ 640 $ 640 $ — $ — Other liabilities: Interest rate swap $ 23 $ — $ 23 $ — Contingent earn-out liability $ 831 $ — $ — $ 831 Derivative Financial Instruments — The Company recognizes derivative instruments as either assets or liabilities in the accompanying Condensed Consolidated Balance Sheets at fair value. The Company records changes in the fair value of the derivatives in the accompanying Condensed Consolidated Statements of Operations as interest and other income (expense), net, or as a component of AOCI in the accompanying Condensed Consolidated Balance Sheets. Inventories — Inventories are stated at the lower of standard cost (which approximates actual cost on a first-in, first-out basis) or market. The Company evaluates the valuation of all inventories, including raw materials, work-in-process, finished goods and spare parts on a periodic basis. Obsolete inventory or inventory in excess of management’s estimated usage is written-down to its estimated market value less costs to sell, if less than its cost. Inherent in the estimates of market value are management’s estimates related to economic trends, future demand for products, and technological obsolescence of the Company’s products. Inventory write downs inherently involve judgments as to assumptions about expected future demand and the impact of market conditions on those assumptions. Although the Company believes that the assumptions it used in estimating inventory write downs are reasonable, significant changes in any one of the assumptions in the future could produce a significantly different result. There can be no assurances that future events and changing market conditions will not result in significant increases in inventory write downs. Equipment and Leasehold Improvements, net — Equipment and leasehold improvements are stated at cost, or, in the case of equipment under capital leases, the present value of future minimum lease payments at inception of the related lease. Depreciation and amortization are computed using the straight-line method over the lesser of the estimated useful lives of the assets or the terms of the leases. Useful lives range from three to fifteen years. Construction in progress is related to the construction or development of property and equipment that has not yet been placed in service for their intended use and is, therefore, not depreciated. Product Warranty — The Company provides warranty on its products for a period of up to two years and provides for warranty costs at the time of sale based on historical activity. Determination of the warranty reserve requires the Company to make estimates of product return rates and expected costs to repair or replace the products under warranty. If actual return rates and/or repair and replacement costs differ significantly from these estimates, adjustments to recognize additional cost of sales may be required in future periods. The warranty reserve is included in other current liabilities on the Condensed Consolidated Balance Sheets. Income Taxes — The Company utilizes the asset and liability method of accounting for income taxes, under which deferred taxes are determined based on the temporary differences between the financial statement and tax basis of assets and liabilities using tax rates expected to be in effect during the years in which the basis differences reverse. Deferred income taxes arise from temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, which will result in taxable or deductible amounts in the future. In evaluating our ability to realize our deferred tax assets within the jurisdiction from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies, and results of recent operations. In projecting future taxable income, we begin with historical results and incorporate assumptions about the amount of future state, federal, and foreign pretax operating income adjusted for items that do not have tax consequences. The assumptions about future taxable income require significant judgment and are consistent with the plans and estimates we are using to manage the underlying businesses. In evaluating the objective evidence that historical results provide, we consider recent cumulative income (loss). A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company continued to maintain a full valuation allowance on its federal, state, and one of its Singapore subsidiary’s deferred tax amounts as of September 23, 2016. Income tax positions must meet a more likely than not recognition threshold to be recognized. Income tax positions that previously failed to meet the more likely than not threshold are recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more likely than not threshold are derecognized in the first subsequent financial reporting period in which that threshold is no longer met. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits within the Condensed Consolidated Statements of Operations as income tax expense. The calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. Resolution of these uncertainties in a manner inconsistent with the Company’s expectations could have a material impact on its results of operations and financial position. Management believes that it has adequately provided for any adjustments that may result from these examinations; however, the outcome of tax audits cannot be predicted with certainty. The determination of the Company’s tax provision is subject to judgments and estimates. Revenue Recognition — Product revenue is generally recorded upon shipment. In arrangements that specify title transfer upon delivery, revenue is not recognized until ownership is transferred to the customer. The Company recognizes revenue when persuasive evidence of an arrangement exists, shipment has occurred, price is fixed or determinable and collectability is reasonably assured. If the Company has not substantially completed a product or fulfilled the terms of a sales agreement at the time of shipment, revenue recognition is deferred until fulfillment. The Company’s standard arrangement for its customers includes a signed purchase order or contract, no right of return of delivered products and no customer acceptance provisions. The Company assesses collectability based on the credit worthiness of the customer and past transaction history. The Company performs on-going credit evaluations of customers and generally does not require collateral from customers. Research and Development Costs — Research and development costs are expensed as incurred. Net Income per Share — Basic net income per share is computed by dividing net income by the weighted average number of shares outstanding for the period. Diluted net income per share is calculated by dividing net income by the weighted average number of common shares outstanding and common equivalent shares from dilutive stock options and restricted stock using the treasury stock method, except when such shares are anti-dilutive. See Note 8 to the Company’s Condensed Consolidated Financial Statements. Segments — The Financial Accounting Standards Board’s (FASB) guidance regarding disclosure about segments in an enterprise and related information establishes standards for the reporting by public business enterprises of information about reportable segments, products and services, geographic areas, and major customers. The method for determining what information to report is based on the manner in which management organizes the reportable segments within the Company for making operational decisions and assessments of financial performance. The Company’s chief operating decision-maker is considered to be the Chief Executive Officer. The Company operates in one reporting segment, and therefore, has one reportable segment. Business Combinations — The Company recognizes assets acquired (including goodwill and identifiable intangible assets) and liabilities assumed at fair value on the acquisition date. Subsequent changes to the fair value of such assets acquired and liabilities assumed are recognized in earnings, after the expiration of the measurement period, a period not to exceed 12 months from the acquisition date. Acquisition-related expenses and acquisition-related restructuring costs are recognized in earnings in the period in which they are incurred. Stock-Based Compensation Expense The Company maintains stock-based compensation plans which allow for the issuance of equity-based awards to executives, directors and certain employees. These equity-based awards include stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) which can be either time-based or performance-based. The Company has not granted stock options to its employees since fiscal year 2010. The Company also maintains an employee stock purchase plan that provides for the issuance of shares to all eligible employees of the Company at a discounted price. Stock-based compensation expense includes compensation costs related to estimated fair values of stock options and awards granted. The estimated fair value of the Company’s equity-based awards, net of expected forfeitures, is amortized on a straight-line basis over the awards’ vesting period, typically three years for RSUs and one year for RSAs, and is adjusted for subsequent changes in estimated forfeitures related to all equity-based awards and performance as it relates to performance-based RSUs. The Company applies the fair value recognition provisions based on the FASB’s guidance regarding stock-based compensation. Stock Options Stock option activity for the nine months ended September 23, 2016: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic (in thousands) Outstanding at December 25, 2015 315,648 $ 10.02 2.06 $ 216 Granted Exercised (100,000 ) 3.96 Cancelled (50,489 ) $ 11.74 Outstanding at September 23, 2016 165,159 $ 13.17 0.74 $ 103 Options exercisable at September 23, 2016 165,159 $ 13.17 0.74 $ 103 There were no options granted by the Company during either of the nine months ended September 23, 2016 and September 25, 2015. As of September 23, 2016, there was no stock-based compensation expense attributable to stock options as all outstanding options were fully vested. Employee Stock Purchase Plan The Company also maintains an employee stock purchase plan (“ESPP”) that provides for the issuance of shares to all eligible employees of the Company at a discounted price. Under the ESPP, substantially all employees may purchase the Company’s common stock through payroll deductions at a price equal to 95 percent of the fair market value of the Company’s stock at the end of each applicable purchase period. Restricted Stock Units and Restricted Stock Awards The Company grants RSUs to employees and RSAs to non-employee directors as part of the Company’s long term equity compensation plan. Restricted Stock Units — RSUs are granted to employees with a per share or unit purchase price of zero dollars and either have time based or performance based vesting. RSUs typically vest over three years, subject to the employee’s continued service with the Company. For purposes of determining compensation expense related to these RSUs, the fair value is determined based on the closing market price of the Company’s common stock on the date of award. The expected cost of the grant is reflected over the service period, and is reduced for estimated forfeitures. During the quarter ended September 23, 2016, the Company granted 138,360 RSUs, with a weighted average fair value of $6.20 per share. During the second quarter ended June 24, 2016, the Company granted 199,000 RSUs, with a weighted average fair value of $5.89 per share, and granted 75,000 performance stock units with a weighted average fair value of $5.93 per share. During the first quarter ended March 25, 2016, the Company granted 644,000 RSUs and PSUs with a weighted average fair value of $5.31 per share. During the nine months ended September 23, 2016, 136,968 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 460,958 shares. As of September 23, 2016, approximately $5.8 million of stock-based compensation cost, net of estimated forfeitures, related to RSUs and PSUs remains to be amortized over a weighted average period of two years. As of September 23, 2016, a total of 1,411,672 RSUs and PSUs remain outstanding with an aggregate intrinsic value of $9.9 million and a weighted average remaining contractual term of 1.3 years. Restricted Stock Awards — As of September 23, 2016, a total of 60,000 RSAs were outstanding. The total unamortized expense of the Company’s unvested restricted stock awards as of September 23, 2016, was $0.2 million. The following table summarizes the Company’s RSU and RSA activity for the nine months ended September 23, 2016: Shares Aggregate Fair (in thousands) Unvested restricted stock units and restricted stock awards at December 25, 2015 1,267,942 $ 6,563 Granted 1,116,360 Vested (645,926 ) Forfeited (266,704 ) Unvested restricted stock units and restricted stock awards at September 23, 2016 1,471,672 $ 10,361 Vested and expected to vest restricted stock units and restricted stock awards at September 23, 2016 1,228,188 $ 8,646 The following table shows the Company’s stock-based compensation expense included in the Condensed Consolidated Statements of Operations (in thousands): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Cost of sales (1) $ 362 $ 304 $ 828 $ 908 Research and development 1,277 658 1,405 1,247 Sales and marketing 76 49 253 150 General and administrative 142 103 1,554 302 1,857 1,114 4,040 2,607 Income tax benefit (935 ) (310 ) (3,979 ) (746 ) Stock-based compensation expense, net of tax $ 922 $ 804 $ 61 $ 1,861 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 23, 2016 and September 25, 2015 were not significant. Recent Accounting Pronouncements In May 2014, the FASB amended the existing accounting standards for revenue recognition. In August 2015, the FASB delayed the effective date of the amended accounting standard for revenue recognition by one year. As such, the updated standard will be effective for the Company in the first quarter of 2018. The Company is still evaluating the effect that the updated standard will have on the consolidated financial statements and related disclosures. In July 2015, the FASB issued authoritative guidance that requires inventory to be measured at the lower of cost and net realizable value instead of at lower of cost or market. This guidance does not apply to inventory that is measured using last-in, first out or the retail inventory method but applies to all other inventory including those measured using first-in, first-out or the average cost method. The authoritative guidance will be effective for the Company in the first quarter of fiscal 2018 and should be applied prospectively. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the effect of this new guidance on the Company’s consolidated financial statements. In April 2015, the FASB issued authoritative guidance that requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, consistent with debt discounts. The Company adopted this guidance with retrospective application in the first quarter of 2016. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In November 2015, the FASB issued authoritative guidance on income taxes, which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as noncurrent on the balance sheet. The updated standard is effective for the Company beginning on January 1, 2017 with early application permitted as of the beginning of any interim or annual reporting period. The Company is currently evaluating the effect of this new guidance on the Company’s consolidated financial statements. In February 2016, the FASB issued new guidance related to how an entity should recognize lease assets and lease liabilities. The guidance specifies that an entity who is a lessee under lease agreements should recognize lease assets and lease liabilities for those leases classified as operating leases under previous FASB guidance. The guidance is effective beginning in the first quarter of 2019. Early adoption is permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the impact of adopting this guidance on the Company’s consolidated financial statements. In March 2016, the FASB issued new guidance which involves several aspects of the accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Under the new standard, income tax benefits and deficiencies are to be recognized as income tax expense or benefit in the income statement and the tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. An entity should also recognize excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. Excess tax benefits should be classified along with other income tax cash flows as an operating activity. In regards to forfeitures, the entity may make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. The guidance is effective for fiscal years beginning after December 15, 2016 including interim periods within that reporting period, however early adoption is permitted. The Company is currently evaluating the guidance to determine the Company's adoption method and the effect it will have on the Company's consolidated financial statements.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 23, 2016
Investments All Other Investments [Abstract]
Financial Instruments	2. Financial Instruments Cash Equivalents As of December 25, 2015, the Company had an overnight sweep account invested in money market funds with maturities of less than 90 days from purchase and is thus classified as cash and cash equivalents on the Company’s balance sheet. The carrying value and fair value of these money market funds as of December 25, 2015 was $0.6 million, based on Level 1 inputs. There were no money market funds as of September 23, 2016. Derivative Financial Instruments A subsidiary of the Company, Miconex, utilizes foreign currency forward contracts with a local financial institution to reduce the risk that its cash flows and earnings will be adversely affected by foreign currency exchange rate fluctuations. The Company also uses certain interest rate derivative contracts to hedge interest rate exposures on existing floating rate debt. The Company classifies its foreign currency and interest rate derivative contracts primarily within Level 2 of the fair-value hierarchy discussed in Note 1 of the Company’s Condensed Consolidated Financial Statements as the valuation inputs are based on quoted prices and market observable data of similar instruments. The Company does not use derivatives for speculative or trading purposes. Cash Flow Hedges In September 2015, the Company entered into an interest rate swap with East West Bank and City National Bank with a notional amount of $20.0 million pursuant to which the Company pays the counterparty a fixed rate of 0.99% and receives interest at a variable rate equal to the London Interbank Offered Rate (LIBOR) rate the Company is required to pay under its term loan, or 0.52%, as of September 23, 2016. This interest rate swap effectively locks in a fixed interest rate of 3.74% on $15.6 million of the $29.2 million term loan as of September 23, 2016, with a decreasing notional amount based on prorated quarterly principal payments over the remaining period of the term loan. Gains or losses on the effective portion of a cash flow hedge are reflected as a component of AOCI and subsequently recorded to interest and other income (expense) when the hedged transactions are realized. If the hedged transactions become probable of not occurring, the corresponding amounts in AOCI would be immediately reclassified to interest and other income (expense), net. As of September 23, 2016, the effective portion of the Company’s cash flow hedge before tax effect was less than $0.1 million, of which less than $0.1 million is expected to be reclassified from AOCI into earnings within the next 12 months. Non-Designated Derivatives The Miconex interest swap to convert the variable interest rates on Miconex debt to fixed rates with a total notional amount of $0.4 million is not designated as a hedging instrument. The Company recognizes gains and losses on this contract, as well any related costs in interest and other income (expense), net. The Company records all derivatives in the Condensed Consolidated Balance Sheets at fair value. The Company’s accounting treatment for these derivative instruments is based on its hedge designation. The following tables show the Company’s derivative instruments at gross fair value (in thousands) as of September 23, 2016 and December 25, 2015. September 23, 2016 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative liabilities: Level 2: Interest rate swap Deferred rent and other liabilities $ 47 $ 9 $ 56 December 25, 2015 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative liabilities: Level 2: Interest rate swap Deferred rent and other liabilities $ 23 $ 10 $ 33 The effect of derivative instruments in cash flow hedging relationships on income and other comprehensive income (OCI) is summarized below (in thousands): Gains (Losses) Recognized in OCI on Derivatives Before Tax Effect (Effective Portion) Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Derivatives in Cash Flow Hedging Relationship Interest rate swap $ 27 $ 87 $ (101 ) $ 87 Gains Reclassified from AOCI into Income (Effective Portion) Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, Income Statement Location 2016 2015 2016 2015 Derivatives in Cash Flow Hedging Relationship Interest rate swap Interest and other income (expense), net $ 20 $ 4 $ 71 $ 4 There were no gains (losses) recognized in income on derivatives that are excluded from the effectiveness testing and ineffective portion of the cash flow hedge for the three and nine months ended September 23, 2016 and September 25, 2015. The effect of derivative instruments not designated as hedging instruments on income for the three and nine months ended September 23, 2016 and September 25, 2015 is not significant to the financial statements.

Balance Sheet Information

Balance Sheet Information	9 Months Ended
	Sep. 23, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Information	3. Balance Sheet Information Inventories consisted of the following (in thousands): September 23, December 25, 2016 2015 Raw materials $ 65,428 $ 57,321 Work in process 23,158 17,954 Finished goods 6,785 4,561 95,371 79,836 Reserve for excess and obsolete (6,356 ) (7,120 ) Total $ 89,015 $ 72,716 Equipment and leasehold improvements, net, consisted of the following (in thousands): September 23, December 25, 2016 2015 Computer equipment and software $ 11,455 $ 10,308 Furniture and fixtures 3,213 3,201 Machinery and equipment 17,026 16,253 Leasehold improvements 17,182 14,951 Construction in progress 2,845 1,168 51,721 45,881 Accumulated depreciation (32,912 ) (28,614 ) Total $ 18,809 $ 17,267

Acquisitions

Acquisitions	9 Months Ended
	Sep. 23, 2016
Business Combinations [Abstract]
Acquisitions	4. Acquisitions Miconex On July 31, 2015, the Company acquired 100.0% of the shareholding interest of Miconex, a limited liability company incorporated under the laws of the Czech Republic and a provider of advanced precision fabrication of plastics, primarily for the semiconductor industry. This acquisition expanded the Company’s capabilities with existing customers. Pursuant to the purchase agreement, the Company paid $15.6 million in cash and issued 500,000 shares of the Company’s common stock. In addition, the former owners of Miconex are entitled up to $4.0 million of potential cash “earn-out” payments over a two-year period following closing, based on Miconex’s achievement of specified performance targets based on earnings before interest and taxes pursuant to the provisions of the purchase agreement. The acquisition price of Miconex for purposes of the Company’s purchase price allocation was determined to be $20.7 million, which includes the cash payment of $15.6 million, the stock consideration valued at $3.8 million and the fair value of the potential earn-out payments of approximately $1.3 million. The fair value of the common stock issued was determined based on the average of the high and low trading prices per share of the Company’s common stock on the acquisition date of approximately $7.64 per share. The fair value of the earn-out payments at the acquisition date was determined providing risk adjusted earnings projections using the Monte Carlo Simulation. These inputs are not observable in the market and thus represent a Level 3 measurement as discussed in Note 1 of the Company’s Consolidated Financial Statements. During the third quarter of fiscal year 2016, the Company reassessed the fair value of the earn-out payments, increasing the fair value from $0.8 million as of December 25, 2015 to $2.2 million as of September 23, 2016. The increase of $1.4 million was recorded as other expense in the Condensed Consolidated Statements of Operations. The Company allocated the purchase price of Miconex to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values. The excess of the purchase price over the aggregate fair value was recorded as goodwill. Goodwill associated with this acquisition is primarily attributable to future technology, market presence and the knowledgeable and experienced workforce. The fair value assigned to identifiable intangible assets acquired was determined using the income approach taking into account the Company’s consideration of a number of inputs, including an independent third party analysis that was based upon estimates and assumptions provided by the Company. These estimates and assumptions were determined through established and generally accepted valuation techniques. The purchase price for this acquisition has been allocated as follows: Fair Market Values (in thousands) Cash and cash equivalents $ 239 Accounts receivable 3,065 Inventories 6,198 Deferred tax assets 196 Prepaid expenses and other 214 Equipment and leasehold improvements 428 Goodwill 10,950 Purchased intangible assets 8,800 Total assets acquired 30,090 Bank borrowings (3,027 ) Accounts payable (3,509 ) Accrued compensation and related benefits (432 ) Other current liabilities (576 ) Deferred tax liability (1,856 ) Other liabilities (24 ) Total liabilities assumed (9,424 ) Purchase price allocated $ 20,666 Purchased Useful Life Intangible Assets (In years) (In thousands) Customer relationships 7.5 $ 8,800 Goodwill is not amortized but is reviewed for impairment at least annually and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Although goodwill is not amortized for financial accounting purposes, it is amortized in its entirety for tax purposes over fifteen years. Marchi On February 5, 2015, the Company acquired 100.0% of the shareholding interest of Marchi, a designer and manufacturer of specialty thermocouples, heaters and temperature controllers, for approximately $29.9 million in cash and 1,437,500 shares of newly issued common stock for a total purchase price of approximately $43.7 million. In addition, the Company incurred approximately $0.2 million of costs related to the acquisition. The Company completed this acquisition primarily in order to expand its capabilities with existing customers and to bring the Company closer to the customer in the design stage of new products and next generation equipment. The Company financed the cash portion of the acquisition by borrowing a total of $29.7 million under a new credit agreement. See further discussion of the borrowing arrangements in Note 6 to the Company’s Condensed Consolidated Financial Statements. The Company allocated the purchase price of Marchi to the tangible assets, liabilities and identifiable intangible assets acquired, based on their calculated fair values. The excess of purchase price over the aggregate fair value was recorded as goodwill. Goodwill associated with the Marchi acquisition is primarily attributable to the future technology, market presence and the knowledgeable and experienced workforce. The fair value assigned to identifiable intangible assets acquired was determined using the income approach taking into account the Company’s consideration of a number of inputs, including an independent third party analysis that was based upon estimates and assumptions provided by the Company. These estimates and assumptions were determined through established and generally accepted valuation techniques. The estimated fair value of the tangible and intangible assets acquired was allocated at Marchi’s acquisition date. The purchase price for this acquisition has been allocated as follows: Fair Market Values (in thousands) Inventories $ 1,297 Equipment and leasehold improvements 767 Goodwill 18,380 Purchased intangible assets 23,370 Other non-current assets 26 Total assets acquired 43,840 Other liabilities (100 ) Total liabilities assumed (100 ) Purchase price allocated $ 43,740 Purchased Useful Life Intangible Assets (In years) (In thousands) Customer relationships 10 $ 9,900 Trade name 6 1,170 Intellectual properties/know-how 8 - 12 12,300 Total purchased intangible assets $ 23,370 The results of operations for the Company for the nine month period ended September 25, 2015 include eight full months of operating activity for Marchi September 25 The following unaudited pro forma consolidated results of operations assume the Marchi and Miconex acquisitions were completed as of the beginning of 2015 fiscal year (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 25, September 25, 2015 2015 Net sales $ 127,348 $ 386,889 Net income $ 1,560 $ 6,049 Basic earnings per share $ 0.05 $ 0.19 Diluted earnings per share $ 0.05 $ 0.19 The unaudited pro forma results above include adjustments related to the purchase price allocation and financing of the Marchi and Miconex acquisitions, primarily to increase amortization for the identifiable intangible assets, to increase interest expense for the additional debt incurred to complete the acquisition of Marchi, to reflect the related income tax effect of the pro forma adjustments and to adjust weighted shares issued as part of the acquisitions. The unaudited pro forma results for the three and nine months ended September 25, 2015 include acquisition related costs of $0.6 million which are not expected to occur in future quarters. The unaudited pro forma condensed combined financial information has been prepared by management for illustrative purposes only and are not necessarily indicative of the condensed consolidated financial position or results of income in future periods or the results that actually would have been realized had UCT, Marchi and Miconex been a combined company during the specified periods. The unaudited pro forma condensed combined financial information does not reflect any operating efficiencies and/or cost savings that we may achieve with respect to the combined companies, or any liabilities that may result from integration activities.

Goodwill and Purchased Intangib

Goodwill and Purchased Intangible Assets	9 Months Ended
	Sep. 23, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Purchased Intangible Assets	5. Goodwill and Purchased Intangible Assets The Company’s methodology for allocating the purchase price relating to purchase acquisitions is determined through established and generally accepted valuation techniques. Goodwill is measured as the excess of the cost of the acquisition over the sum of the amounts assigned to tangible and identifiable intangible assets acquired less liabilities assumed. Goodwill and purchased intangible assets with indefinite useful lives are not amortized, but are reviewed for impairment at least annually and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. The Company regularly monitors current business conditions and other factors including, but not limited to, adverse industry or economic trends and lower projections of profitability that may impact future operating results. To test goodwill for impairment, the Company first performs a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If it is concluded that this is the case, the Company then performs the two-step goodwill impairment test. Otherwise, the two-step goodwill impairment test is not required. Under the two-step goodwill impairment test, the Company would in the first step compare the estimated fair value of each reporting unit to its carrying value. The Company determines the fair value of each of its reporting units based on a weighting of income and market approaches. If the carrying value of a reporting unit exceeds its fair value, the Company would then perform the second step of the impairment test in order to determine the implied fair value of the reporting unit’s goodwill. If the Company determines that the carrying value of a reporting unit’s goodwill exceeds its implied fair value, the Company would record an impairment charge equal to the difference. The evaluation of goodwill and intangible assets for impairment requires the exercise of significant judgment. In the event of future changes in business conditions, the Company will be required to reassess and update its forecasts and estimates used in future impairment analyses. If the results of these future analyses are lower than current estimates, a material impairment charge may result at that time. Details of goodwill and other intangible assets were as follows (in thousands): September 23, 2016 December 25, 2015 Intangible Intangible Goodwill Assets Total Goodwill Assets Total Carrying amount $ 85,248 $ 38,464 $ 123,712 $ 85,248 $ 42,782 $ 128,030 Purchased Intangible Assets Intangible assets are generally recorded in connection with a business acquisition. The Company evaluates the useful lives of its intangible assets each reporting period to determine whether events and circumstances require revising the remaining period of amortization. In addition, the Company reviews indefinite lived intangible assets for impairment when events or changes in circumstances indicate their carrying value may not be recoverable and tests definite lives intangible assets at least annually for impairment. Management considers such indicators as significant differences in product demand from the estimates, changes in the competitive and economic environment, technological advances, and changes in cost structure. Details of purchased intangible assets were as follows (in thousands): As of September 23, 2016 As of December 25, 2015 Gross Gross Carrying Accumulated Carrying Carrying Accumulated Carrying Useful Amount Amortization Value Amount Amortization Value Life AIT Customer relationships $ 19,000 $ (16,618 ) $ 2,382 $ 19,000 $ (15,298 ) $ 3,702 7 Tradename 1,900 (1,900 ) — 1,900 (1,900 ) — 6 Intellectual property/know-how 1,600 (971 ) 629 1,600 (800 ) 800 7 Marchi Customer relationships 9,900 (1,650 ) 8,250 9,900 (907 ) 8,993 10 Tradename 1,170 (387 ) 783 1,170 (217 ) 953 6 Intellectual property/know-how 12,300 (2,298 ) 10,002 12,300 (1,264 ) 11,036 8-12 Miconex Customer relationships 8,800 (1,369 ) 7,431 8,800 (489 ) 8,311 7.5 UCT Tradename 8,987 — 8,987 8,987 — 8,987 * Total $ 63,657 $ (25,193 ) $ 38,464 $ 63,657 $ (20,875 ) $ 42,782 * The Company concluded that the UCT tradename intangible asset life is indefinite and is therefore not amortized but is reviewed for impairment at least annually and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. The Company amortizes its tradenames for AIT and Marchi and customer relationships intangible asset for AIT using an accelerated method over the estimated economic life of the assets, ranging from 6 to 7 years. The Company amortizes its intellectual property/know-how and customer relationships intangible assets for Marchi and Miconex on a straight-line basis with an estimated economic life of the assets ranging from 7 to 12 years. Amortization expense was approximately $1.4 million and $1.6 million for the three months ended September 23, 2016 and September 25, 2015, respectively, and $4.3 million and $4.0 million for the nine months ended September 23, 2016 and September 25, 2015, respectively. Amortization expense is charged to general and administrative. As of September 23, 2016, future estimated amortization expense is expected to be as follows (in thousands): Amortization Expense 2016 (remaining in year) $ 1,439 2017 4,924 2018 4,582 2019 4,210 2020 3,682 Thereafter 10,640 Total $ 29,477

Borrowing Arrangements

Borrowing Arrangements	9 Months Ended
	Sep. 23, 2016
Debt Disclosure [Abstract]
Borrowing Arrangements	6. Borrowing Arrangements On February 2, 2015, the Company entered into a credit agreement (the “Credit Agreement”) by and among the Company, certain of its subsidiaries and East West Bank and City National Bank (collectively, the “Lenders”). The credit agreement was amended on April 3, 2015 (as amended, the “Credit Agreement”). The Credit Agreement provides for a term loan in an aggregate principal amount of $40.0 million (the “Term Loan”) and a revolving credit facility in an aggregate principal amount of $40.0 million (the “Revolving Credit Facility”), a letter of credit facility in the aggregate availability amount of $20.0 million (as a sublimit of such Revolving Credit Facility) (the “L/C Facility”) and a swingline sub-facility in the aggregate availability amount of $5.0 million (as a sublimit of the Revolving Credit Facility) (together with the Term Loan, the Revolving Credit Facility and the L/C Facility, the “Senior Secured Credit Facility”). On February 2, 2015, the Company borrowed an aggregate of $40.0 million under the Term Loan and approximately $6.5 million under the Revolving Credit Facility. The borrowed funds were used to repay the outstanding balance to Silicon Valley Bank as lender under our prior loan agreement, which loan agreement was terminated in connection with this transaction. In addition, the Company expensed the unamortized debt issuance costs relating to the prior loan agreement of approximately $0.7 million in the first quarter of 2015. On February 5, 2015, in order to finance the acquisition of Marchi, the Company borrowed $29.7 million under the Revolving Credit Facility. The Term Loan must be repaid in consecutive quarterly installments of $1.25 million for the first four installments and $2.9 million for the remaining twelve installments, with the first payment made on March 31, 2015, and with the balance of the outstanding principal amount of the Term Loan due at the final maturity, which is February 2, 2019. The Revolving Credit Facility is available for the four-year period beginning on February 2, 2015. The Credit Agreement includes customary representations, warranties, covenants and events of default. The Company and certain of its subsidiaries have agreed to secure all of their obligations under the Credit Agreement by granting a first priority lien in substantially all of their respective personal property assets (subject to certain exceptions and limitations). At the Company’s option, borrowings under the Term Loan and Revolving Credit Facility (subject to certain limitations) bear interest at either a base rate or at the LIBOR (with the LIBOR being adjusted for certain Eurocurrency reserve requirements, if any, as described in the Credit Agreement), plus, in each case, an applicable margin based on the Company’s consolidated leverage ratio. All loans described above made on February 2, 2015 were initially base rate loans, carrying interest of 3.25%. The effective interest rate will be higher due to the incurrence of certain loan-related costs of $0.6 million that have been treated as a discount on the debt and amortized over the life of the loan. As of September 23, 2016, the interest rates on the outstanding Term Loan and Revolving Credit facility were 3.27% (2.75% applicable margin and 0.52% LIBOR) and 3.50% fixed, respectively. In order to manage interest rate risk on the variable component of the Term Loan, the Company entered into an interest rate swap with the Lenders in September 2015 with a total notional amount of $20.0 million (which amount decreases based on prorated quarterly principal payments over the remaining period of the Term Loan) pursuant to which the Company pays the counterparty a fixed rate of 0.99% and receives interest at a variable rate equal to the LIBOR rate the Company is required to pay under its Term Loan, or 0.52%, as of September 23, 2016. This interest rate swap effectively locks in a fixed interest rate of 3.74% on $15.5 million of the $29.2 million term loan balance outstanding as of September 23, 2016. The Credit Agreement requires the Company to maintain certain financial covenants including a consolidated fixed charge coverage ratio (as defined in the Credit Agreement) of at least 1.25 to 1.00 starting with the end of the first quarter of fiscal 2015 and a consolidated leverage ratio (as defined in the Credit Agreement) no greater than 3.50 to 1.00 starting with the end of the first quarter of fiscal 2015. The Credit Agreement also includes other customary affirmative and negative covenants. In December 2015, the Credit Agreement was amended to add a covenant requiring the Company to maintain a cash balance of $35.0 million at the end of each quarter. The Company was in compliance with all covenants for the quarter ended September 23, 2016. The Credit Agreement also contains provisions requiring the following mandatory prepayments (subject to certain exceptions and limitations): annual prepayments in an amount equal to (a) 33.0% of excess cash flow (as defined in the Credit Agreement) if the aggregate outstanding principal amount of the Term Loan equals or exceeds $20.0 million and (b) 25.0% of excess cash flow if the aggregate outstanding principal amount of the Term Loan equals or exceeds $10.0 million but is less than $20.0 million. The Credit Agreement also restricts us from declaring or paying any cash dividends. The fair value of the Company’s long term debt was based on Level 2 inputs, and fair value was determined using quoted prices for similar liabilities in inactive markets. The fair value of the Company’s outstanding borrowings under the Company’s revolving credit facility was based on Level 2 inputs, and fair value was determined using inputs other than quoted prices that are observable, specifically, discounted cash flows of expected payments at current borrowing rates. The Company’s carrying value approximates fair value for the Company’s long term debt and revolving credit facility. As of September 23, 2016, the outstanding amounts under the Term Loan and Revolving Credit Facility were $29.2 million and $36.2 million, respectively, gross of unamortized debt issuance costs of $0.4 million. In conjunction with the acquisition of Miconex in July 2015, the Company has a credit agreement with a local bank in the Czech Republic that provides for a term loan in an aggregate of 0.8 million euros and a revolving credit facility in the aggregate of up to 4.5 million euros. As of September 23, 2016, Miconex had outstanding amounts under the term loan and the revolving credit facility of 0.5 million euros (approximately $0.5 million) and 3.3 million euros (approximately $3.7 million), respectively, for a total of $4.2 million, with interest rates ranging from 1.3% to 2.3% plus a variable rate based on the Euro Interbank Offered Rate with due dates ranging from 2016 to 2020. As of September 23, 2016, the Company’s total bank debt was $69.2 million. As of September 23, 2016, the Company has $3.8 million and 1.2 million euros (approximately $1.4 million) available to borrow on its revolving loans in the U.S. and Czech Republic, respectively.

Income Tax

Income Tax	9 Months Ended
	Sep. 23, 2016
Income Tax Disclosure [Abstract]
Income Tax	7. Income Tax The Company’s income tax provision and effective tax rates for the three and nine months ended September 23, 2016 were $2.8 million and 51.3% and $6.4 million and 98.5%, respectively compared to $0.6 million and 27.8% and $2.0 million and 28.6%, respectively for the three and nine months ended September 25, 2015. The change in respective rates reflects, primarily, changes in the geographic mix of worldwide earnings and financial results, as well as the impact of losses in jurisdictions with full federal and state valuation allowances for the three and nine months ended September 23, 2016 compared to the impact of losses in jurisdictions with full state valuation allowances for the three and nine months ended September 25, 2015. Company management continuously evaluates the need for a valuation allowance and, as of September 23, 2016, concluded that a full valuation allowance on its federal and state deferred tax assets as well as the deferred tax assets of one its Singapore subsidiaries was still appropriate. The Company earns a significant amount of its operating income outside the United States, which is deemed to be indefinitely reinvested in foreign jurisdictions, except as disclosed below. As a result, most of the Company’s cash and cash equivalents are held by foreign subsidiaries. The Company currently does not intend nor foresee a need to repatriate any other funds to the U.S., except for a portion of current year earnings from one of our Singapore subsidiaries. The Company expects domestic cash and cash flows from operations to continue to be sufficient to fund its domestic operating activities and cash commitments for investing and financing activities, such as debt repayment and capital expenditures, for at least the next 12 months and thereafter for the foreseeable future. If the Company should require more capital in the U.S. than is generated by its domestic operations, for example to fund significant discretionary activities such as business acquisitions, the Company could elect to repatriate future earnings from foreign jurisdictions or raise capital in the United States through debt or equity issuances. These alternatives could result in higher effective tax rates, increased interest expense, or dilution of our earnings. The Company has borrowed funds domestically and continues to believe it has the ability to do so at reasonable interest rates. The Company does not provide for U.S. taxes on its undistributed earnings of foreign subsidiaries that it intends to invest indefinitely outside the U.S., unless such taxes are otherwise required under U.S. tax law. In 2016, the Company determined that a portion of the current year earnings of one of its China subsidiaries may be remitted in the future to one of its foreign subsidiaries outside of mainland China and, accordingly, the Company provided for the related withholding taxes in its condensed consolidated financial statements. If the Company changes its intent to reinvest its undistributed foreign earnings indefinitely or if a greater amount of undistributed earnings are needed than the previous anticipated remaining unremitted foreign earnings, the Company could be required to accrue or pay U.S. taxes on some or all of these undistributed earnings. As of September 23, 2016, the Company had undistributed earnings of foreign subsidiaries that are indefinitely invested outside of the U.S. of approximately $80.8 million. It is not practicable to determine the income tax liability that might be incurred if these earnings were to be distributed. The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands): Nine Months Ended September 23, September 25, 2016 2015 Balance as of the beginning of period $ 337 $ 356 Increase related to current year tax positions 61 — Expiration of the statute of limitations for the assessment of taxes (24 ) (26 ) Balance as of the end of period $ 374 $ 330 The Company’s gross liability for unrecognized tax benefits as of September 23, 2016 and December 25, 2015 was $0.4 million and $0.3 million, respectively. Increases or decreases to interest and penalties on uncertain tax positions are included in the income tax provision in the Condensed Consolidated Statements of Operations. Interest related to uncertain tax positions was considered to be de minimis The determination of the Company’s tax provision is subject to judgments and estimates. The carrying value of the Company’s net deferred tax assets, which is made up primarily of tax deductions and net operating loss carryforwards, assumes the Company will be able to generate sufficient future income to fully realize the income tax benefit. In determining whether the realization of these deferred tax assets may be impaired, the Company makes judgments with respect to whether the Company is likely to generate sufficient future taxable income to realize these assets. In addition, the calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. Resolution of these uncertainties in a manner inconsistent with the Company’s expectations could have a material impact on the Company’s results of operations and financial position. The Company files income tax returns in the U.S. federal jurisdiction, various states and foreign jurisdictions. The Company’s 2013 through 2015 federal income tax returns are open to audit through the statute of limitations by the Internal Revenue Service. The Company’s 2012 through 2015 state income tax returns are open to audit by the California Franchise Tax Board. The Company is also subject to examination in various other jurisdictions for various periods.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 23, 2016
Earnings Per Share [Abstract]
Net Income Per Share	8. Net Income Per Share Basic net income per share excludes dilution and is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that would occur if outstanding securities or other contracts to issue common stock were exercised or converted into common stock. The following is a reconciliation of the numerators and denominators used in computing basic and diluted net income per share (in thousands, except per share data): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Numerator: Net income $ 2,614 $ 1,676 $ 98 $ 5,056 Denominator: Shares used in computation — basic: Weighted average common shares outstanding 32,759 31,993 32,544 31,359 Shares used in computation — diluted: Shares used in computing basic net income per share 32,759 31,993 32,544 31,359 Dilutive effect of common shares outstanding subject to repurchase 313 110 305 222 Dilutive effect of options outstanding 28 52 38 72 Weighted average shares used in computing diluted net income per share 33,100 32,155 32,887 31,653 Net income per share — basic $ 0.08 $ 0.05 $ 0.00 $ 0.16 Net income per share — diluted $ 0.08 $ 0.05 $ 0.00 $ 0.16 The Company had securities outstanding which could potentially dilute basic net income per share in the future, but the incremental shares from the assumed exercise of these securities were excluded in the computation of diluted net income per share, as their effect would have been anti-dilutive. Such outstanding securities consisted of 174,202 and 187,389 stock options for the three and nine month periods ended September 23, 2016, respectively and 204,154 and 281,507 stock options for the three and nine month periods ended September 25, 2015, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 23, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies The Company had commitments to purchase inventory totaling approximately $74.3 million at September 23, 2016. The Company leases properties domestically in Hayward, California; Austin, Texas; Pflugerville, Texas; Chandler, Arizona; and South San Francisco, California and internationally in China, Singapore, Philippines and the Czech Republic. The Company leases certain of its facilities under non-cancelable leases, which expire on various dates through 2022. As of September 23, 2016, future minimum payments under these operating leases were as follows (in thousands): Fiscal Year 2016 (remaining in year) $ 1,732 2017 6,071 2018 5,388 2019 4,412 2020 4,096 Thereafter 6,658 Total minimum lease payments $ 28,357 From time to time, the Company is subject to various legal proceedings and claims, either asserted or unasserted, that arise in the ordinary course of business. Although the outcome of the various legal proceedings and claims cannot be predicted with certainty, the Company has not had a history of outcomes to date that have been material to the statement of operations and does not believe that any of these proceedings or other claims will have a material adverse effect on its consolidated financial condition or results of operations.

Segment and Geographic Informat

Segment and Geographic Information	9 Months Ended
	Sep. 23, 2016
Segment Reporting [Abstract]
Segment and Geographic Information	10. Segment and Geographic Information The Company operates in one operating and reportable segment as the nature of the Company’s products and production processes, as well as type of customers and distribution methods, is consistent among all of the Company’s products and is engaged in the development, manufacture and supply of critical subsystems for the semiconductor capital equipment, consumer, medical, energy, industrial, flat panel and research industries. The Company’s foreign operations are conducted primarily through its wholly-owned subsidiaries in China, Singapore and the Czech Republic. The Company’s principal markets include North America, Asia and Europe. Sales by geographic area represent sales to unaffiliated customers and are based upon the location to which the products were shipped. The following table sets forth revenue by geographic area (in thousands): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 United States $ 83,296 $ 82,708 $ 217,026 $ 252,138 China 6,961 1,017 11,593 18,267 Singapore 39,310 29,952 115,353 77,354 Austria 7,994 5,059 25,805 5,059 Other 8,593 4,080 18,437 12,865 $ 146,154 $ 122,816 $ 388,214 $ 365,683 At September 23, 2016, approximately $7.4 million and $1.8 million of the Company’s net long-lived assets were located in Asia and the Czech Republic, respectively, and the remaining balances were located in the United States. At September 25, 2015, approximately $9.8 million and $0.5 million of the Company’s net long-lived assets were located in Asia and the Czech Republic, respectively, and the remaining balances were located in the United States.

Organization and Significant 17

Organization and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 23, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation — The unaudited condensed consolidated financial statements included in this quarterly report on Form 10-Q include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). This financial information reflects all adjustments which are, in the opinion of the Company, normal, recurring and necessary for the fair financial statement presentation for the dates and periods presented. Certain information and footnote disclosures normally included in our annual financial statements, prepared in accordance with GAAP, have been condensed or omitted. The Company’s December 25, 2015 balance sheet data were derived from its audited financial statements as of that date.
Principles of Consolidation	Principles of Consolidation — The Company’s condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and all intercompany accounts and transactions have been eliminated in consolidation. The Company uses a 52-53 week fiscal year ending on the Friday nearest December 31. All references to quarters refer to fiscal quarters and all references to years refer to fiscal years.
Foreign Currency Translation and Remeasurement	Foreign Currency Translation and Remeasurement — The Company has one foreign subsidiary whose functional currency is not its local currency or the U.S. dollar. The Company remeasures the monetary assets and liabilities of this subsidiary into its functional currency. Gains and losses from these remeasurements are recorded in interest and other income (expense), net. The Company then translates the assets and liabilities of this subsidiary into the U.S. dollar. Gains and losses from these translations are recognized in foreign currency translation included in accumulated other comprehensive income (AOCI) within stockholders’ equity. For the Company’s foreign subsidiaries where the U.S. dollar is the functional currency, any gains and losses resulting from the remeasurement of the assets and liabilities of these subsidiaries are recorded in interest and other income (expense), net.
Use of Accounting Estimates	Use of Accounting Estimates — The presentation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Such estimates and assumptions include reserves on inventory, valuation of deferred tax assets and impairment of goodwill and other long-lived assets. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, future events are subject to change and the best estimates and judgments routinely require adjustment. Actual amounts may differ from those estimates
Concentration of Credit Risk	Concentration of Credit Risk — Financial instruments which subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable. The Company sells its products primarily to semiconductor capital equipment manufacturers in the United States. The Company performs credit evaluations of its customers’ financial condition and generally requires no collateral
Significant sales to customers	Significant Sales to Customers — The Company’s most significant customers (having accounted for 10% or more of sales) and their related sales as a percentage of total sales were as follows: Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Lam Research Corporation 49.5 % 49.4 % 53.5 % 50.4 % Applied Materials, Inc. 30.9 26.4 27.3 27.1 Total 80.4 % 75.8 % 80.8 % 77.5 % Two customers’ accounts receivable balances, Lam Research Corporation and Applied Materials, Inc., were individually greater than 10% of accounts receivable as of September 23, 2016 and three customers’ accounts receivable balances, Lam Research Corporation, Applied Materials, Inc. and ASM International, Inc., were individually greater than 10% of accounts receivable as of December 25, 2015, and in the aggregate represented approximately 77.9% and 84.6% of accounts receivable as of September 23, 2016 and December 25, 2015, respectively.
Fair Value of Measurements	Fair Value of Measurements — The Company measures its cash equivalents, interest rate derivative contracts and contingent earn-out liability at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that is determined based on assumptions that market participants would use in pricing an asset or a liability. Assets and liabilities recorded at fair value are measured and classified in accordance with a three-tier fair value hierarchy based on the observability of the inputs available in the market used to measure fair value: Level 1 — Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2 — Inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, foreign exchange rates, and credit ratings. Level 3 — Unobservable inputs that are supported by little or no market activities. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The following table summarizes, for assets or liabilities measured at fair value, the respective fair value and the classification by level of input within the fair value hierarchy (in thousands): Fair Value Measurement at Reporting Date Using Description September 23, 2016 Quoted Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other liabilities: Interest rate swap $ 56 $ — $ 56 $ — Contingent earn-out liability $ 2,236 $ — $ — $ 2,236 Fair Value Measurement at Reporting Date Using Description December 25, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash and cash equivalents: Money market fund deposits $ 640 $ 640 $ — $ — Other liabilities: Interest rate swap $ 23 $ — $ 23 $ — Contingent earn-out liability $ 831 $ — $ — $ 831
Derivative Financial Instruments	Derivative Financial Instruments — The Company recognizes derivative instruments as either assets or liabilities in the accompanying Condensed Consolidated Balance Sheets at fair value. The Company records changes in the fair value of the derivatives in the accompanying Condensed Consolidated Statements of Operations as interest and other income (expense), net, or as a component of AOCI in the accompanying Condensed Consolidated Balance Sheets.
Inventories	Inventories — Inventories are stated at the lower of standard cost (which approximates actual cost on a first-in, first-out basis) or market. The Company evaluates the valuation of all inventories, including raw materials, work-in-process, finished goods and spare parts on a periodic basis. Obsolete inventory or inventory in excess of management’s estimated usage is written-down to its estimated market value less costs to sell, if less than its cost. Inherent in the estimates of market value are management’s estimates related to economic trends, future demand for products, and technological obsolescence of the Company’s products. Inventory write downs inherently involve judgments as to assumptions about expected future demand and the impact of market conditions on those assumptions. Although the Company believes that the assumptions it used in estimating inventory write downs are reasonable, significant changes in any one of the assumptions in the future could produce a significantly different result. There can be no assurances that future events and changing market conditions will not result in significant increases in inventory write downs.
Equipment and Leasehold Improvements	Equipment and Leasehold Improvements, net — Equipment and leasehold improvements are stated at cost, or, in the case of equipment under capital leases, the present value of future minimum lease payments at inception of the related lease. Depreciation and amortization are computed using the straight-line method over the lesser of the estimated useful lives of the assets or the terms of the leases. Useful lives range from three to fifteen years. Construction in progress is related to the construction or development of property and equipment that has not yet been placed in service for their intended use and is, therefore, not depreciated.
Product Warranty	Product Warranty — The Company provides warranty on its products for a period of up to two years and provides for warranty costs at the time of sale based on historical activity. Determination of the warranty reserve requires the Company to make estimates of product return rates and expected costs to repair or replace the products under warranty. If actual return rates and/or repair and replacement costs differ significantly from these estimates, adjustments to recognize additional cost of sales may be required in future periods. The warranty reserve is included in other current liabilities on the Condensed Consolidated Balance Sheets.
Income Taxes	Income Taxes — The Company utilizes the asset and liability method of accounting for income taxes, under which deferred taxes are determined based on the temporary differences between the financial statement and tax basis of assets and liabilities using tax rates expected to be in effect during the years in which the basis differences reverse. Deferred income taxes arise from temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, which will result in taxable or deductible amounts in the future. In evaluating our ability to realize our deferred tax assets within the jurisdiction from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies, and results of recent operations. In projecting future taxable income, we begin with historical results and incorporate assumptions about the amount of future state, federal, and foreign pretax operating income adjusted for items that do not have tax consequences. The assumptions about future taxable income require significant judgment and are consistent with the plans and estimates we are using to manage the underlying businesses. In evaluating the objective evidence that historical results provide, we consider recent cumulative income (loss). A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company continued to maintain a full valuation allowance on its federal, state, and one of its Singapore subsidiary’s deferred tax amounts as of September 23, 2016. Income tax positions must meet a more likely than not recognition threshold to be recognized. Income tax positions that previously failed to meet the more likely than not threshold are recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more likely than not threshold are derecognized in the first subsequent financial reporting period in which that threshold is no longer met. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits within the Condensed Consolidated Statements of Operations as income tax expense. The calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. Resolution of these uncertainties in a manner inconsistent with the Company’s expectations could have a material impact on its results of operations and financial position. Management believes that it has adequately provided for any adjustments that may result from these examinations; however, the outcome of tax audits cannot be predicted with certainty. The determination of the Company’s tax provision is subject to judgments and estimates.
Revenue Recognition	Revenue Recognition — Product revenue is generally recorded upon shipment. In arrangements that specify title transfer upon delivery, revenue is not recognized until ownership is transferred to the customer. The Company recognizes revenue when persuasive evidence of an arrangement exists, shipment has occurred, price is fixed or determinable and collectability is reasonably assured. If the Company has not substantially completed a product or fulfilled the terms of a sales agreement at the time of shipment, revenue recognition is deferred until fulfillment. The Company’s standard arrangement for its customers includes a signed purchase order or contract, no right of return of delivered products and no customer acceptance provisions. The Company assesses collectability based on the credit worthiness of the customer and past transaction history. The Company performs on-going credit evaluations of customers and generally does not require collateral from customers.
Research and Development Costs	Research and Development Costs — Research and development costs are expensed as incurred.
Net Income per Share	Net Income per Share — Basic net income per share is computed by dividing net income by the weighted average number of shares outstanding for the period. Diluted net income per share is calculated by dividing net income by the weighted average number of common shares outstanding and common equivalent shares from dilutive stock options and restricted stock using the treasury stock method, except when such shares are anti-dilutive. See Note 8 to the Company’s Condensed Consolidated Financial Statements.
Segments	Segments — The Financial Accounting Standards Board’s (FASB) guidance regarding disclosure about segments in an enterprise and related information establishes standards for the reporting by public business enterprises of information about reportable segments, products and services, geographic areas, and major customers. The method for determining what information to report is based on the manner in which management organizes the reportable segments within the Company for making operational decisions and assessments of financial performance. The Company’s chief operating decision-maker is considered to be the Chief Executive Officer. The Company operates in one reporting segment, and therefore, has one reportable segment.
Business Combinations	Business Combinations — The Company recognizes assets acquired (including goodwill and identifiable intangible assets) and liabilities assumed at fair value on the acquisition date. Subsequent changes to the fair value of such assets acquired and liabilities assumed are recognized in earnings, after the expiration of the measurement period, a period not to exceed 12 months from the acquisition date. Acquisition-related expenses and acquisition-related restructuring costs are recognized in earnings in the period in which they are incurred.
Stock-Based Compensation Expense	Stock-Based Compensation Expense The Company maintains stock-based compensation plans which allow for the issuance of equity-based awards to executives, directors and certain employees. These equity-based awards include stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) which can be either time-based or performance-based. The Company has not granted stock options to its employees since fiscal year 2010. The Company also maintains an employee stock purchase plan that provides for the issuance of shares to all eligible employees of the Company at a discounted price. Stock-based compensation expense includes compensation costs related to estimated fair values of stock options and awards granted. The estimated fair value of the Company’s equity-based awards, net of expected forfeitures, is amortized on a straight-line basis over the awards’ vesting period, typically three years for RSUs and one year for RSAs, and is adjusted for subsequent changes in estimated forfeitures related to all equity-based awards and performance as it relates to performance-based RSUs. The Company applies the fair value recognition provisions based on the FASB’s guidance regarding stock-based compensation.
Stock Options	Stock Options Stock option activity for the nine months ended September 23, 2016: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic (in thousands) Outstanding at December 25, 2015 315,648 $ 10.02 2.06 $ 216 Granted Exercised (100,000 ) 3.96 Cancelled (50,489 ) $ 11.74 Outstanding at September 23, 2016 165,159 $ 13.17 0.74 $ 103 Options exercisable at September 23, 2016 165,159 $ 13.17 0.74 $ 103 There were no options granted by the Company during either of the nine months ended September 23, 2016 and September 25, 2015. As of September 23, 2016, there was no stock-based compensation expense attributable to stock options as all outstanding options were fully vested.
Employee Stock Purchase Plan	Employee Stock Purchase Plan The Company also maintains an employee stock purchase plan (“ESPP”) that provides for the issuance of shares to all eligible employees of the Company at a discounted price. Under the ESPP, substantially all employees may purchase the Company’s common stock through payroll deductions at a price equal to 95 percent of the fair market value of the Company’s stock at the end of each applicable purchase period.
Restricted Stock Units and Restricted Stock Awards	Restricted Stock Units and Restricted Stock Awards The Company grants RSUs to employees and RSAs to non-employee directors as part of the Company’s long term equity compensation plan. Restricted Stock Units — RSUs are granted to employees with a per share or unit purchase price of zero dollars and either have time based or performance based vesting. RSUs typically vest over three years, subject to the employee’s continued service with the Company. For purposes of determining compensation expense related to these RSUs, the fair value is determined based on the closing market price of the Company’s common stock on the date of award. The expected cost of the grant is reflected over the service period, and is reduced for estimated forfeitures. During the quarter ended September 23, 2016, the Company granted 138,360 RSUs, with a weighted average fair value of $6.20 per share. During the second quarter ended June 24, 2016, the Company granted 199,000 RSUs, with a weighted average fair value of $5.89 per share, and granted 75,000 performance stock units with a weighted average fair value of $5.93 per share. During the first quarter ended March 25, 2016, the Company granted 644,000 RSUs and PSUs with a weighted average fair value of $5.31 per share. During the nine months ended September 23, 2016, 136,968 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 460,958 shares. As of September 23, 2016, approximately $5.8 million of stock-based compensation cost, net of estimated forfeitures, related to RSUs and PSUs remains to be amortized over a weighted average period of two years. As of September 23, 2016, a total of 1,411,672 RSUs and PSUs remain outstanding with an aggregate intrinsic value of $9.9 million and a weighted average remaining contractual term of 1.3 years. Restricted Stock Awards — As of September 23, 2016, a total of 60,000 RSAs were outstanding. The total unamortized expense of the Company’s unvested restricted stock awards as of September 23, 2016, was $0.2 million. The following table summarizes the Company’s RSU and RSA activity for the nine months ended September 23, 2016: Shares Aggregate Fair (in thousands) Unvested restricted stock units and restricted stock awards at December 25, 2015 1,267,942 $ 6,563 Granted 1,116,360 Vested (645,926 ) Forfeited (266,704 ) Unvested restricted stock units and restricted stock awards at September 23, 2016 1,471,672 $ 10,361 Vested and expected to vest restricted stock units and restricted stock awards at September 23, 2016 1,228,188 $ 8,646 The following table shows the Company’s stock-based compensation expense included in the Condensed Consolidated Statements of Operations (in thousands): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Cost of sales (1) $ 362 $ 304 $ 828 $ 908 Research and development 1,277 658 1,405 1,247 Sales and marketing 76 49 253 150 General and administrative 142 103 1,554 302 1,857 1,114 4,040 2,607 Income tax benefit (935 ) (310 ) (3,979 ) (746 ) Stock-based compensation expense, net of tax $ 922 $ 804 $ 61 $ 1,861 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 23, 2016 and September 25, 2015 were not significant.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB amended the existing accounting standards for revenue recognition. In August 2015, the FASB delayed the effective date of the amended accounting standard for revenue recognition by one year. As such, the updated standard will be effective for the Company in the first quarter of 2018. The Company is still evaluating the effect that the updated standard will have on the consolidated financial statements and related disclosures. In July 2015, the FASB issued authoritative guidance that requires inventory to be measured at the lower of cost and net realizable value instead of at lower of cost or market. This guidance does not apply to inventory that is measured using last-in, first out or the retail inventory method but applies to all other inventory including those measured using first-in, first-out or the average cost method. The authoritative guidance will be effective for the Company in the first quarter of fiscal 2018 and should be applied prospectively. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the effect of this new guidance on the Company’s consolidated financial statements. In April 2015, the FASB issued authoritative guidance that requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, consistent with debt discounts. The Company adopted this guidance with retrospective application in the first quarter of 2016. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In November 2015, the FASB issued authoritative guidance on income taxes, which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as noncurrent on the balance sheet. The updated standard is effective for the Company beginning on January 1, 2017 with early application permitted as of the beginning of any interim or annual reporting period. The Company is currently evaluating the effect of this new guidance on the Company’s consolidated financial statements. In February 2016, the FASB issued new guidance related to how an entity should recognize lease assets and lease liabilities. The guidance specifies that an entity who is a lessee under lease agreements should recognize lease assets and lease liabilities for those leases classified as operating leases under previous FASB guidance. The guidance is effective beginning in the first quarter of 2019. Early adoption is permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the impact of adopting this guidance on the Company’s consolidated financial statements. In March 2016, the FASB issued new guidance which involves several aspects of the accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Under the new standard, income tax benefits and deficiencies are to be recognized as income tax expense or benefit in the income statement and the tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. An entity should also recognize excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. Excess tax benefits should be classified along with other income tax cash flows as an operating activity. In regards to forfeitures, the entity may make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. The guidance is effective for fiscal years beginning after December 15, 2016 including interim periods within that reporting period, however early adoption is permitted. The Company is currently evaluating the guidance to determine the Company's adoption method and the effect it will have on the Company's consolidated financial statements.

Organization and Significant 18

Organization and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 23, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Customers as Percentage of Total Sales	The Company’s most significant customers (having accounted for 10% or more of sales) and their related sales as a percentage of total sales were as follows: Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Lam Research Corporation 49.5 % 49.4 % 53.5 % 50.4 % Applied Materials, Inc. 30.9 26.4 27.3 27.1 Total 80.4 % 75.8 % 80.8 % 77.5 %
Assets or Liabilities Measured at Fair Value	The following table summarizes, for assets or liabilities measured at fair value, the respective fair value and the classification by level of input within the fair value hierarchy (in thousands): Fair Value Measurement at Reporting Date Using Description September 23, 2016 Quoted Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other liabilities: Interest rate swap $ 56 $ — $ 56 $ — Contingent earn-out liability $ 2,236 $ — $ — $ 2,236 Fair Value Measurement at Reporting Date Using Description December 25, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash and cash equivalents: Money market fund deposits $ 640 $ 640 $ — $ — Other liabilities: Interest rate swap $ 23 $ — $ 23 $ — Contingent earn-out liability $ 831 $ — $ — $ 831
Schedule of Option Activity	Stock option activity for the nine months ended September 23, 2016: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic (in thousands) Outstanding at December 25, 2015 315,648 $ 10.02 2.06 $ 216 Granted Exercised (100,000 ) 3.96 Cancelled (50,489 ) $ 11.74 Outstanding at September 23, 2016 165,159 $ 13.17 0.74 $ 103 Options exercisable at September 23, 2016 165,159 $ 13.17 0.74 $ 103
Summary of Restricted Stock Unit and Restricted Stock Award Activity	The following table summarizes the Company’s RSU and RSA activity for the nine months ended September 23, 2016: Shares Aggregate Fair (in thousands) Unvested restricted stock units and restricted stock awards at December 25, 2015 1,267,942 $ 6,563 Granted 1,116,360 Vested (645,926 ) Forfeited (266,704 ) Unvested restricted stock units and restricted stock awards at September 23, 2016 1,471,672 $ 10,361 Vested and expected to vest restricted stock units and restricted stock awards at September 23, 2016 1,228,188 $ 8,646
Stock-Based Compensation Expense Included in Condensed Consolidated Statements of Operations	The following table shows the Company’s stock-based compensation expense included in the Condensed Consolidated Statements of Operations (in thousands): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Cost of sales (1) $ 362 $ 304 $ 828 $ 908 Research and development 1,277 658 1,405 1,247 Sales and marketing 76 49 253 150 General and administrative 142 103 1,554 302 1,857 1,114 4,040 2,607 Income tax benefit (935 ) (310 ) (3,979 ) (746 ) Stock-based compensation expense, net of tax $ 922 $ 804 $ 61 $ 1,861 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 23, 2016 and September 25, 2015 were not significant.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 23, 2016
Investments All Other Investments [Abstract]
Schedule of Derivative Instruments at Gross Fair Value	The following tables show the Company’s derivative instruments at gross fair value (in thousands) as of September 23, 2016 and December 25, 2015. September 23, 2016 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative liabilities: Level 2: Interest rate swap Deferred rent and other liabilities $ 47 $ 9 $ 56 December 25, 2015 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative liabilities: Level 2: Interest rate swap Deferred rent and other liabilities $ 23 $ 10 $ 33
Effect of Derivative Instruments in Cash Flow Hedging Relationships on Income and Other Comprehensive Income	The effect of derivative instruments in cash flow hedging relationships on income and other comprehensive income (OCI) is summarized below (in thousands): Gains (Losses) Recognized in OCI on Derivatives Before Tax Effect (Effective Portion) Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Derivatives in Cash Flow Hedging Relationship Interest rate swap $ 27 $ 87 $ (101 ) $ 87 Gains Reclassified from AOCI into Income (Effective Portion) Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, Income Statement Location 2016 2015 2016 2015 Derivatives in Cash Flow Hedging Relationship Interest rate swap Interest and other income (expense), net $ 20 $ 4 $ 71 $ 4

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	9 Months Ended
	Sep. 23, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Inventories	Inventories consisted of the following (in thousands): September 23, December 25, 2016 2015 Raw materials $ 65,428 $ 57,321 Work in process 23,158 17,954 Finished goods 6,785 4,561 95,371 79,836 Reserve for excess and obsolete (6,356 ) (7,120 ) Total $ 89,015 $ 72,716
Equipment and Leasehold Improvements, Net	Equipment and leasehold improvements, net, consisted of the following (in thousands): September 23, December 25, 2016 2015 Computer equipment and software $ 11,455 $ 10,308 Furniture and fixtures 3,213 3,201 Machinery and equipment 17,026 16,253 Leasehold improvements 17,182 14,951 Construction in progress 2,845 1,168 51,721 45,881 Accumulated depreciation (32,912 ) (28,614 ) Total $ 18,809 $ 17,267

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 23, 2016
Schedule of Allocation of Purchase Price for Acquisition	The purchase price for this acquisition has been allocated as follows: Fair Market Values (in thousands) Inventories $ 1,297 Equipment and leasehold improvements 767 Goodwill 18,380 Purchased intangible assets 23,370 Other non-current assets 26 Total assets acquired 43,840 Other liabilities (100 ) Total liabilities assumed (100 ) Purchase price allocated $ 43,740
Summary of Purchased Intangible Assets	Purchased Useful Life Intangible Assets (In years) (In thousands) Customer relationships 10 $ 9,900 Trade name 6 1,170 Intellectual properties/know-how 8 - 12 12,300 Total purchased intangible assets $ 23,370
Unaudited Proforma Consolidated Results of Operations	The following unaudited pro forma consolidated results of operations assume the Marchi and Miconex acquisitions were completed as of the beginning of 2015 fiscal year (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 25, September 25, 2015 2015 Net sales $ 127,348 $ 386,889 Net income $ 1,560 $ 6,049 Basic earnings per share $ 0.05 $ 0.19 Diluted earnings per share $ 0.05 $ 0.19
Miconex [Member]
Schedule of Allocation of Purchase Price for Acquisition	The purchase price for this acquisition has been allocated as follows: Fair Market Values (in thousands) Cash and cash equivalents $ 239 Accounts receivable 3,065 Inventories 6,198 Deferred tax assets 196 Prepaid expenses and other 214 Equipment and leasehold improvements 428 Goodwill 10,950 Purchased intangible assets 8,800 Total assets acquired 30,090 Bank borrowings (3,027 ) Accounts payable (3,509 ) Accrued compensation and related benefits (432 ) Other current liabilities (576 ) Deferred tax liability (1,856 ) Other liabilities (24 ) Total liabilities assumed (9,424 ) Purchase price allocated $ 20,666
Summary of Purchased Intangible Assets	Purchased Useful Life Intangible Assets (In years) (In thousands) Customer relationships 7.5 $ 8,800

Goodwill and Purchased Intang22

Goodwill and Purchased Intangible Assets (Tables)	9 Months Ended
	Sep. 23, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Indefinite Lived Intangible Assets	Details of goodwill and other intangible assets were as follows (in thousands): September 23, 2016 December 25, 2015 Intangible Intangible Goodwill Assets Total Goodwill Assets Total Carrying amount $ 85,248 $ 38,464 $ 123,712 $ 85,248 $ 42,782 $ 128,030
Details of Purchased Intangible Assets	Details of purchased intangible assets were as follows (in thousands): As of September 23, 2016 As of December 25, 2015 Gross Gross Carrying Accumulated Carrying Carrying Accumulated Carrying Useful Amount Amortization Value Amount Amortization Value Life AIT Customer relationships $ 19,000 $ (16,618 ) $ 2,382 $ 19,000 $ (15,298 ) $ 3,702 7 Tradename 1,900 (1,900 ) — 1,900 (1,900 ) — 6 Intellectual property/know-how 1,600 (971 ) 629 1,600 (800 ) 800 7 Marchi Customer relationships 9,900 (1,650 ) 8,250 9,900 (907 ) 8,993 10 Tradename 1,170 (387 ) 783 1,170 (217 ) 953 6 Intellectual property/know-how 12,300 (2,298 ) 10,002 12,300 (1,264 ) 11,036 8-12 Miconex Customer relationships 8,800 (1,369 ) 7,431 8,800 (489 ) 8,311 7.5 UCT Tradename 8,987 — 8,987 8,987 — 8,987 * Total $ 63,657 $ (25,193 ) $ 38,464 $ 63,657 $ (20,875 ) $ 42,782 * The Company concluded that the UCT tradename intangible asset life is indefinite and is therefore not amortized but is reviewed for impairment at least annually and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable.
Future Estimated Amortization Expense	As of September 23, 2016, future estimated amortization expense is expected to be as follows (in thousands): Amortization Expense 2016 (remaining in year) $ 1,439 2017 4,924 2018 4,582 2019 4,210 2020 3,682 Thereafter 10,640 Total $ 29,477

Income Tax (Tables)

Income Tax (Tables)	9 Months Ended
	Sep. 23, 2016
Income Tax Disclosure [Abstract]
Activity Related to Company's Unrecognized Tax Benefits	The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands): Nine Months Ended September 23, September 25, 2016 2015 Balance as of the beginning of period $ 337 $ 356 Increase related to current year tax positions 61 — Expiration of the statute of limitations for the assessment of taxes (24 ) (26 ) Balance as of the end of period $ 374 $ 330

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 23, 2016
Earnings Per Share [Abstract]
Basic and Diluted Net Income Per Share	The following is a reconciliation of the numerators and denominators used in computing basic and diluted net income per share (in thousands, except per share data): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 Numerator: Net income $ 2,614 $ 1,676 $ 98 $ 5,056 Denominator: Shares used in computation — basic: Weighted average common shares outstanding 32,759 31,993 32,544 31,359 Shares used in computation — diluted: Shares used in computing basic net income per share 32,759 31,993 32,544 31,359 Dilutive effect of common shares outstanding subject to repurchase 313 110 305 222 Dilutive effect of options outstanding 28 52 38 72 Weighted average shares used in computing diluted net income per share 33,100 32,155 32,887 31,653 Net income per share — basic $ 0.08 $ 0.05 $ 0.00 $ 0.16 Net income per share — diluted $ 0.08 $ 0.05 $ 0.00 $ 0.16

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 23, 2016
Commitments And Contingencies Disclosure [Abstract]
Summary of Future Minimum Payments under Operating Leases	As of September 23, 2016, future minimum payments under these operating leases were as follows (in thousands): Fiscal Year 2016 (remaining in year) $ 1,732 2017 6,071 2018 5,388 2019 4,412 2020 4,096 Thereafter 6,658 Total minimum lease payments $ 28,357

Segment and Geographic Inform26

Segment and Geographic Information (Tables)	9 Months Ended
	Sep. 23, 2016
Segment Reporting [Abstract]
Revenue by Geographic Area	The following table sets forth revenue by geographic area (in thousands): Three Months Ended Nine Months Ended September 23, September 25, September 23, September 25, 2016 2015 2016 2015 United States $ 83,296 $ 82,708 $ 217,026 $ 252,138 China 6,961 1,017 11,593 18,267 Singapore 39,310 29,952 115,353 77,354 Austria 7,994 5,059 25,805 5,059 Other 8,593 4,080 18,437 12,865 $ 146,154 $ 122,816 $ 388,214 $ 365,683

Organization and Significant 27

Organization and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016CustomerSegment	Sep. 25, 2015	Dec. 25, 2015Customer
Concentration Risk [Line Items]
Number of reportable segments | Segment			1
Minimum [Member]
Concentration Risk [Line Items]
Fiscal year duration			364 days
Useful lives range			3 years
Maximum [Member]
Concentration Risk [Line Items]
Fiscal year duration			371 days
Useful lives range			15 years
Product warranty period (in years)			2 years
Measurement period to determine fair value of assets and liabilities			12 months
Customer Concentration Risk [Member] | Lam Research Corporation and Applied Materials, Inc. [Member]
Concentration Risk [Line Items]
Number of customers with accounts receivable greater than 10% | Customer			2		3
Sales [Member] | International Sales [Member]
Concentration Risk [Line Items]
Concentration percentage	49.70%	35.60%	46.50%	33.30%
Sales [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration percentage	80.40%	75.80%	80.80%	77.50%
Accounts Receivable | Customer Concentration Risk [Member] | Lam Research Corporation, Applied Materials, Inc. and ASM International, Inc. [Member]
Concentration Risk [Line Items]
Concentration percentage			77.90%		84.60%

Organization and Significant 28

Organization and Significant Accounting Policies - Customers as Percentage of Total Sales (Detail) - Sales [Member] - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Concentration Risk [Line Items]
Total	80.40%	75.80%	80.80%	77.50%
Lam Research Corporation [Member]
Concentration Risk [Line Items]
Total	49.50%	49.40%	53.50%	50.40%
Applied Materials, Inc. [Member]
Concentration Risk [Line Items]
Total	30.90%	26.40%	27.30%	27.10%

Organization and Significant 29

Organization and Significant Accounting Policies - Assets or Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Money Market Fund Deposits [Member]
Other liabilities:
Assets or liabilities measured at fair value		$ 640
Cash and cash equivalents:
Assets or liabilities measured at fair value		640
Interest Rate Swap [Member]
Other liabilities:
Assets or liabilities measured at fair value	$ 56	23
Cash and cash equivalents:
Assets or liabilities measured at fair value	56	23
Contingent Earn-out Liability [Member]
Other liabilities:
Assets or liabilities measured at fair value	2,236	831
Cash and cash equivalents:
Assets or liabilities measured at fair value	2,236	831
Level 1 [Member] | Money Market Fund Deposits [Member]
Other liabilities:
Assets or liabilities measured at fair value		640
Cash and cash equivalents:
Assets or liabilities measured at fair value		640
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Swap [Member]
Other liabilities:
Assets or liabilities measured at fair value	56	23
Cash and cash equivalents:
Assets or liabilities measured at fair value	56	23
Significant Unobservable Inputs (Level 3) [Member] | Contingent Earn-out Liability [Member]
Other liabilities:
Assets or liabilities measured at fair value	2,236	831
Cash and cash equivalents:
Assets or liabilities measured at fair value	$ 2,236	$ 831

Organization and Significant 30

Organization and Significant Accounting Policies - Additional Information 1 (Detail) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Sep. 23, 2016	Sep. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted				0
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				3 years
Granted, stock shares	138,360	199,000	644,000
Weighted average fair value, granted	$ 6.20	$ 5.89	$ 5.31
Vested shares withheld to satisfy withholding tax obligations				136,968
Vested shares issued net of tax withholdings				460,958
Stock-based compensation cost, net of estimated forfeitures, recognized				$ 5,800,000
Outstanding restricted stock	1,411,672			1,411,672
Aggregate fair value	$ 9,900,000			$ 9,900,000
Weighted average remaining contractual term (in years)				1 year 3 months 18 days
Restricted Stock Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				2 years
Restricted Stock Units [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				3 years
Unit purchase price of Restricted Stock Units				$ 0
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				1 year
Restricted Stock Awards [Member] | Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding restricted stock	60,000			60,000
Unamortized expense of company's unvested restricted stock awards	$ 200,000			$ 200,000
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted				0	0
Stock-based compensation expense				$ 0
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee common stock fair market value rate				95.00%
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, stock shares		75,000	644,000
Weighted average fair value, granted		$ 5.93	$ 5.31
Stock-based compensation cost, net of estimated forfeitures, recognized				$ 5,800,000
Outstanding restricted stock	1,411,672			1,411,672
Aggregate fair value	$ 9,900,000			$ 9,900,000
Weighted average remaining contractual term (in years)				1 year 3 months 18 days

Organization and Significant 31

Organization and Significant Accounting Policies - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 23, 2016	Dec. 25, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Shares, Beginning balance	315,648
Granted, Shares	0
Exercised, Shares	(100,000)
Cancelled, Shares	(50,489)
Outstanding, Shares, Ending balance	165,159	315,648
Options exercisable, Shares	165,159
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 10.02
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	3.96
Canceled, Weighted Average Exercise Price	11.74
Weighted Average Exercise Price, Outstanding, Ending balance	13.17	$ 10.02
Options exercisable, Weighted Average Exercise Price	$ 13.17
Weighted Average Remaining Contractual Life (years), Outstanding	8 months 27 days	2 years 22 days
Weighted Average Remaining Contractual Life (years), Options exercisable	8 months 27 days
Aggregate Intrinsic Value, Outstanding, Beginning balance	$ 216
Aggregate Intrinsic Value, Outstanding, Ending balance	103	$ 216
Aggregate Intrinsic Value, Options exercisable	$ 103

Organization and Significant 32

Organization and Significant Accounting Policies - Summary of Restricted Stock Unit and Restricted Stock Award Activity (Detail) - Restricted Stock Unit and Restricted Stock Award [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 23, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units and restricted stock awards, Number of Shares, Beginning balance	1,267,942
Granted, Number of Shares	1,116,360
Vested, Number of Shares	(645,926)
Forfeited, Number of Shares	(266,704)
Unvested restricted stock units and restricted stock awards, Number of Shares, Ending balance	1,471,672
Vested and expected to vest restricted stock units and restricted stock awards, Number of Shares	1,228,188
Unvested restricted stock units and restricted stock awards, Beginning balance, Aggregate Intrinsic Value	$ 6,563
Unvested restricted stock units and restricted stock awards, Ending balance, Aggregate Intrinsic Value	10,361
Vested and expected to vest restricted stock units and restricted stock awards, Aggregate Intrinsic Value	$ 8,646

Organization and Significant 33

Organization and Significant Accounting Policies - Stock-Based Compensation Expense Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 1,857	$ 1,114	$ 4,040	$ 2,607
Income tax benefit	(935)	(310)	(3,979)	(746)
Stock-based compensation expense, net of tax	922	804	61	1,861
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	362	304	828	908
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	1,277	658	1,405	1,247
Sales and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	76	49	253	150
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 142	$ 103	$ 1,554	$ 302

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015	Dec. 25, 2015	Sep. 30, 2015	Dec. 26, 2014
Financial Instruments [Line Items]
Cash and cash equivalents	$ 47,270,000	$ 59,783,000	$ 47,270,000	$ 59,783,000	$ 50,103,000		$ 78,997,000
Miconex [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Financial Instruments [Line Items]
Non-Designated Derivatives, description			The Miconex interest swap to convert the variable interest rates on Miconex debt to fixed rates with a total notional amount of $0.4 million is not designated as a hedging instrument. The Company recognizes gains and losses on this contract, as well any related costs in interest and other income (expense), net.
Maximum [Member]
Financial Instruments [Line Items]
Effective portion of cash flow hedge before tax effect			$ 100,000
Cash flow hedge, expected to be reclassified from AOCI into earnings			100,000
Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Outstanding amounts	29,200,000		29,200,000
Interest Rate Swap [Member] | Miconex [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount	400,000		$ 400,000
East West and City National Bank [Member] | Interest Rate Swap [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount						$ 20,000,000
Credit Agreement [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount						$ 20,000,000
Debt instrument variable interest rate			2.75%
Credit Agreement [Member] | Interest Rate Swap [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount	$ 15,500,000		$ 15,500,000
Debt instrument LIBOR rate						0.99%
Debt instrument interest rate	3.74%		3.74%
Credit Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Debt instrument variable interest rate			0.52%
Derivatives in Cash Flow Hedging Relationship [Member]
Financial Instruments [Line Items]
Gains (losses) recognized in income on derivatives that are excluded from effectiveness testing and ineffective portion	$ 0	$ 0	$ 0	$ 0
Derivatives in Cash Flow Hedging Relationship [Member] | East West and City National Bank [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Debt instrument interest rate	3.74%		3.74%
Outstanding amounts	$ 29,200,000		$ 29,200,000
Derivatives in Cash Flow Hedging Relationship [Member] | East West and City National Bank [Member] | Interest Rate Swap [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount	15,600,000		15,600,000
Money Market Fund Deposits [Member]
Financial Instruments [Line Items]
Cash and cash equivalents	0		0		600,000
Money Market Fund Deposits [Member] | Level 1 [Member]
Financial Instruments [Line Items]
Fair value of cash and cash equivalents	$ 0		$ 0		$ 600,000

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments at Gross Fair Value (Detail) - Interest Rate Swap [Member] - Significant Other Observable Inputs (Level 2) [Member] - Deferred Rent and Other Liabilities [Member] - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Derivatives, Fair Value [Line Items]
Derivative liabilities, Fair Value of Derivatives Designated as Hedge Instrument	$ 47	$ 23
Derivative liabilities, Fair Value of Derivatives Not Designated as Hedge Instrument	9	10
Derivative liabilities, Total Fair Value	$ 56	$ 33

Financial Instruments - Effect

Financial Instruments - Effect of Derivative Instruments in Cash Flow Hedging Relationships on Income and Other Comprehensive Income (Detail) - Interest Rate Swap [Member] - Derivatives in Cash Flow Hedging Relationship [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Recognized in OCI on Derivatives Before Tax Effect (Effective Portion)	$ 27	$ 87	$ (101)	$ 87
Interest and Other Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains Reclassified from AOCI into Income (Effective Portion)	$ 20	$ 4	$ 71	$ 4

Balance Sheet Information - Sum

Balance Sheet Information - Summary of Inventories (Detail) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 65,428	$ 57,321
Work in process	23,158	17,954
Finished goods	6,785	4,561
Inventory, gross	95,371	79,836
Reserve for excess and obsolete	(6,356)	(7,120)
Total	$ 89,015	$ 72,716

Balance Sheet Information - Equ

Balance Sheet Information - Equipment and Leasehold Improvements, Net (Detail) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	$ 51,721	$ 45,881
Accumulated depreciation	(32,912)	(28,614)
Total	18,809	17,267
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	11,455	10,308
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	3,213	3,201
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	17,026	16,253
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	17,182	14,951
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	$ 2,845	$ 1,168

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($)	Jul. 31, 2015	Feb. 05, 2015	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015	Dec. 25, 2015
Business Acquisition [Line Items]
Business acquisition, potential cash earn-out payments				$ 1,280,000		$ 1,280,000
Stock consideration for acquisition	$ 3,800,000
Change in the fair value of the contingent earn out	$ 1,300,000				$ 1,405,000
Fair value of common stock per share	$ 7.64
Goodwill amortization period					15 years
Net sales			$ 146,154,000	122,816,000	$ 388,214,000	365,683,000
Operating income			6,700,000	3,079,000	9,721,000	9,155,000
Amortization of finite-lived intangibles			1,400,000	1,600,000	4,318,000	4,042,000
Miconex [Member]
Business Acquisition [Line Items]
Percentage of shareholding interest acquired	100.00%
Cash paid for acquisition	$ 15,600,000
Business acquisition, potential cash earn-out payments			2,200,000		2,200,000		$ 800,000
Business acquisition, potential cash payments period	2 years
Purchase price allocated	$ 20,700,000		20,666,000		20,666,000
Change in the fair value of the contingent earn out					1,400,000
Miconex [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business acquisition, potential cash earn-out payments	$ 4,000,000
Miconex [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares of newly issued common stock	500,000
Marchi Thermal Systems Inc [Member]
Business Acquisition [Line Items]
Percentage of shareholding interest acquired		100.00%
Cash paid for acquisition		$ 29,900,000
Shares of newly issued common stock		1,437,500
Purchase price allocated			$ 43,740,000		$ 43,740,000
Total purchase price		$ 43,700,000
Acquisition costs		200,000
Amount borrowed to finance cash portion of acquisition		$ 29,700,000
Net sales				3,900,000		10,100,000
Operating income				1,700,000		4,400,000
Amortization of finite-lived intangibles				700,000		1,700,000
Marchi Thermal Systems Inc [Member] | General and Administrative [Member]
Business Acquisition [Line Items]
Acquisition costs						200,000
Marchi Thermal Systems Inc and Miconex S.r.o. [Member]
Business Acquisition [Line Items]
Acquisition related costs				$ 600,000		$ 600,000

Acquisitions - Schedule of Allo

Acquisitions - Schedule of Allocation of Purchase Price for Acquisition (Detail) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015	Jul. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 85,248	$ 85,248
Miconex [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	239
Accounts receivable	3,065
Inventories	6,198
Deferred tax assets	196
Prepaid expenses and other	214
Equipment and leasehold improvements	428
Goodwill	10,950
Purchased intangible assets	8,800
Total assets acquired	30,090
Bank borrowings	(3,027)
Accounts payable	(3,509)
Accrued compensation and related benefits	(432)
Other current liabilities	(576)
Deferred tax liability	(1,856)
Other liabilities	(24)
Total liabilities assumed	(9,424)
Purchase price allocated	20,666		$ 20,700
Marchi Thermal Systems Inc [Member]
Business Acquisition [Line Items]
Inventories	1,297
Equipment and leasehold improvements	767
Goodwill	18,380
Purchased intangible assets	23,370
Other non-current assets	26
Total assets acquired	43,840
Other liabilities	(100)
Total liabilities assumed	(100)
Purchase price allocated	$ 43,740

Acquisitions - Summary of Purch

Acquisitions - Summary of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 23, 2016	Dec. 25, 2015
Miconex [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets	$ 8,800
Marchi Thermal Systems Inc [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets	$ 23,370
Customer Relationships [Member] | Miconex [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets, Useful Life	7 years 6 months	7 years 6 months
Purchased intangible assets	$ 8,800	$ 8,800
Customer Relationships [Member] | Marchi Thermal Systems Inc [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets, Useful Life	10 years	10 years
Purchased intangible assets	$ 9,900	$ 9,900
Trade Name [Member] | Marchi Thermal Systems Inc [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets, Useful Life	6 years	6 years
Purchased intangible assets	$ 1,170	$ 1,170
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets	$ 12,300	$ 12,300
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets, Useful Life	8 years	8 years
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Purchased intangible assets, Useful Life	12 years	12 years

Acquisitions - Unaudited Pro fo

Acquisitions - Unaudited Pro forma Consolidated Results of Operations (Detail) - Marchi Thermal Systems Inc and Miconex S.r.o. [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 25, 2015	Sep. 25, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net sales	$ 127,348	$ 386,889
Net income	$ 1,560	$ 6,049
Basic earnings per share	$ 0.05	$ 0.19
Diluted earnings per share	$ 0.05	$ 0.19

Goodwill and Purchased Intang43

Goodwill and Purchased Intangible Assets - Goodwill and Other Indefinite Lived Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Intangible Assets Net Including Goodwill [Abstract]
Goodwill	$ 85,248	$ 85,248
Intangible Assets	38,464	42,782
Total	$ 123,712	$ 128,030

Goodwill and Purchased Intang44

Goodwill and Purchased Intangible Assets - Details of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 23, 2016	Dec. 25, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 63,657	$ 63,657
Accumulated Amortization	(25,193)	(20,875)
Carrying Value	38,464	42,782
American Integration Technologies LLC [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	19,000	19,000
Accumulated Amortization	(16,618)	(15,298)
Carrying Value	2,382	$ 3,702
Useful Life (in years)		7 years
American Integration Technologies LLC [Member] | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,900	$ 1,900
Accumulated Amortization	(1,900)	$ (1,900)
Useful Life (in years)		6 years
American Integration Technologies LLC [Member] | Intellectual Properties/Know-How [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,600	$ 1,600
Accumulated Amortization	(971)	(800)
Carrying Value	629	$ 800
Useful Life (in years)		7 years
Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	23,370
Marchi Thermal Systems Inc [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9,900	$ 9,900
Accumulated Amortization	(1,650)	(907)
Carrying Value	$ 8,250	$ 8,993
Useful Life (in years)	10 years	10 years
Marchi Thermal Systems Inc [Member] | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,170	$ 1,170
Accumulated Amortization	(387)	(217)
Carrying Value	$ 783	$ 953
Useful Life (in years)	6 years	6 years
Marchi Thermal Systems Inc [Member] | Intellectual Properties/Know-How [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 12,300	$ 12,300
Accumulated Amortization	(2,298)	(1,264)
Carrying Value	$ 10,002	$ 11,036
Marchi Thermal Systems Inc [Member] | Intellectual Properties/Know-How [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	8 years	8 years
Marchi Thermal Systems Inc [Member] | Intellectual Properties/Know-How [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	12 years	12 years
Miconex [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,800
Miconex [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,800	$ 8,800
Accumulated Amortization	(1,369)	(489)
Carrying Value	$ 7,431	$ 8,311
Useful Life (in years)	7 years 6 months	7 years 6 months
UCT [Member] | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,987	$ 8,987
Carrying Value	$ 8,987	$ 8,987

Goodwill and Purchased Intang45

Goodwill and Purchased Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization of finite-lived intangibles	$ 1,400	$ 1,600	$ 4,318	$ 4,042
Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of finite-lived intangibles		$ 700		$ 1,700
Trade Name [Member] | American Integration Technologies LLC [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Trade Name [Member] | American Integration Technologies LLC [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Trade Name [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Trade Name [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | American Integration Technologies LLC [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Customer Relationships [Member] | American Integration Technologies LLC [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Customer Relationships [Member] | Miconex [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Miconex [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Intellectual Properties/Know-How [Member] | Miconex [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Intellectual Properties/Know-How [Member] | Miconex [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years

Goodwill and Purchased Intang46

Goodwill and Purchased Intangible Assets - Future Estimated Amortization Expense (Detail) $ in Thousands	Sep. 23, 2016USD ($)
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
2016 (remaining in year)	$ 1,439
2,017	4,924
2,018	4,582
2,019	4,210
2,020	3,682
Thereafter	10,640
Total	$ 29,477

Borrowing Arrangements - Additi

Borrowing Arrangements - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Mar. 27, 2015USD ($)	Sep. 23, 2016USD ($)	Sep. 23, 2016EUR (€)	Sep. 30, 2015USD ($)	Jul. 31, 2015EUR (€)	Feb. 05, 2015USD ($)	Feb. 02, 2015USD ($)
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 700,000	$ 400,000
Amortization of debt discount		$ 600,000
Required cash balance	$ 35,000,000
Debt Instrument, covenant description		The Credit Agreement requires the Company to maintain certain financial covenants including a consolidated fixed charge coverage ratio (as defined in the Credit Agreement) of at least 1.25 to 1.00 starting with the end of the first quarter of fiscal 2015 and a consolidated leverage ratio (as defined in the Credit Agreement) no greater than 3.50 to 1.00 starting with the end of the first quarter of fiscal 2015. The Credit Agreement also includes other customary affirmative and negative covenants. In December 2015, the Credit Agreement was amended to add a covenant requiring the Company to maintain a cash balance of $35.0 million at the end of each quarter. The Company was in compliance with all covenants for the quarter ended September 23, 2016.
Percentage of excess cash flow used for annual debt payment condition one		33.00%
Term loan principal amount outstanding condition one		$ 20,000,000
Percentage of excess cash flow used for annual debt payment condition two		25.00%
Minimum [Member]
Debt Instrument [Line Items]
Fixed charge coverage ratio for the next fiscal year	1.25%
Term loan principal amount outstanding condition two		$ 10,000,000
Maximum [Member]
Debt Instrument [Line Items]
Term loan principal amount outstanding condition two		$ 20,000,000
First Quarter [Member] | Maximum [Member]
Debt Instrument [Line Items]
Consolidated leverage ratio for first quarter of next fiscal year	3.50%
Marchi Thermal Systems Inc [Member]
Debt Instrument [Line Items]
Outstanding amount of borrowing under credit facility						$ 29,700,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit agreement amendment date		Apr. 3, 2015
Outstanding amount of borrowing under credit facility							$ 6,500,000
Line of credit facility maturity period		4 years
Outstanding amounts		$ 36,200,000
Revolving Credit Facility [Member] | Marchi Thermal Systems Inc [Member]
Debt Instrument [Line Items]
Outstanding amount of borrowing under credit facility						$ 29,700,000
Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding amount of borrowing under credit facility							40,000,000
Maturity date of debt		Feb. 2, 2019
Base rate interest		3.27%
Outstanding amounts		$ 29,200,000
Term Loan Credit Facility [Member] | First Four Quarter [Member]
Debt Instrument [Line Items]
Term loan repaid		1,250,000
Term Loan Credit Facility [Member] | Remaining Twelve Quarter [Member]
Debt Instrument [Line Items]
Term loan repaid		$ 2,900,000
Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility							40,000,000
Debt instrument interest rate		3.50%	3.50%
Credit Agreement [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility							40,000,000
Debt instrument variable interest rate		2.75%
Derivative instrument, notional amount				$ 20,000,000
Credit Agreement [Member] | Term Loan Credit Facility [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Debt instrument interest rate		3.74%	3.74%
Derivative instrument, notional amount		$ 15,500,000
Debt instrument LIBOR rate				0.99%
Credit Agreement [Member] | Term Loan Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate		0.52%
Credit Agreement [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility							20,000,000
Credit Agreement [Member] | Swing Line Sub-Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility							$ 5,000,000
Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt instrument interest rate		3.25%	3.25%
Bank Debt [Member]
Debt Instrument [Line Items]
Total debt balance		$ 69,200,000
Bank Debt [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Debt due date, start year		2,016
Debt due date, end year		2,020
Bank Debt [Member] | Minimum [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate		1.30%
Bank Debt [Member] | Maximum [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate		2.30%
Bank Debt [Member] | Miconex [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 4,200,000
Bank Debt [Member] | Revolving Credit Facility [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Outstanding amounts		1,400,000	€ 1,200,000
Bank Debt [Member] | Revolving Credit Facility [Member] | U.S. [Member]
Debt Instrument [Line Items]
Outstanding amounts		3,800,000
Bank Debt [Member] | Revolving Credit Facility [Member] | Miconex [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Outstanding amounts		3,700,000	3,300,000
Bank Debt [Member] | Revolving Credit Facility [Member] | Miconex [Member] | Maximum [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility | €					€ 4,500,000
Bank Debt [Member] | Term Loan Credit Facility [Member] | Miconex [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility | €					€ 800,000
Outstanding amounts		$ 500,000	€ 500,000

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015	Dec. 25, 2015	Dec. 26, 2014
Income Tax Disclosure [Abstract]
Income tax provision	$ 2,750	$ 647	$ 6,360	$ 2,028
Effective tax rate	51.30%	27.80%	98.50%	28.60%
Undistributed earnings of foreign subsidiaries	$ 80,800		$ 80,800
Gross liability for unrecognized tax benefits	$ 374	$ 330	$ 374	$ 330	$ 337	$ 356

Income Tax - Activity Related t

Income Tax - Activity Related to Company's Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015
Income Tax Disclosure [Abstract]
Balance as of the beginning of period	$ 337	$ 356
Increase related to current year tax positions	61
Expiration of the statute of limitations for the assessment of taxes	(24)	(26)
Balance as of the end of period	$ 374	$ 330

Net Income Per Share - Basic an

Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Numerator:
Net income	$ 2,614	$ 1,676	$ 98	$ 5,056
Shares used in computation — basic:
Weighted average common shares outstanding	32,759	31,993	32,544	31,359
Shares used in computation — diluted:
Shares used in computing basic net income per share	32,759	31,993	32,544	31,359
Dilutive effect of common shares outstanding subject to repurchase	313	110	305	222
Dilutive effect of options outstanding	28	52	38	72
Weighted average shares used in computing diluted net income per share	33,100	32,155	32,887	31,653
Net income per share — basic	$ 0.08	$ 0.05	$ 0	$ 0.16
Net income per share — diluted	$ 0.08	$ 0.05	$ 0	$ 0.16

Net Income Per Share - Addition

Net Income Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Employee Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	174,202	204,154	187,389	281,507

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 23, 2016USD ($)
Long-term Purchase Commitment [Line Items]
Operating lease expiration period	Various dates through 2022
Inventory [Member]
Long-term Purchase Commitment [Line Items]
Purchase commitments	$ 74.3

Commitments and Contingencies53

Commitments and Contingencies - Summary of Future Minimum Payments under Operating Leases (Detail) $ in Thousands	Sep. 23, 2016USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2016 (remaining in year)	$ 1,732
2,017	6,071
2,018	5,388
2,019	4,412
2,020	4,096
Thereafter	6,658
Total minimum lease payments	$ 28,357

Segment and Geographic Inform54

Segment and Geographic Information - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 23, 2016USD ($)Segment	Sep. 25, 2015USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segment	1
Number of reportable segments | Segment	1
Other Asia [Member]
Segment Reporting Information [Line Items]
Net long-lived assets | $	$ 7.4	$ 9.8
Czech Republic [Member]
Segment Reporting Information [Line Items]
Net long-lived assets | $	$ 1.8	$ 0.5

Segment and Geographic Inform55

Segment and Geographic Information - Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Segment Reporting Information [Line Items]
Sales	$ 146,154	$ 122,816	$ 388,214	$ 365,683
United States [Member]
Segment Reporting Information [Line Items]
Sales	83,296	82,708	217,026	252,138
China [Member]
Segment Reporting Information [Line Items]
Sales	6,961	1,017	11,593	18,267
Singapore [Member]
Segment Reporting Information [Line Items]
Sales	39,310	29,952	115,353	77,354
Austria [Member]
Segment Reporting Information [Line Items]
Sales	7,994	5,059	25,805	5,059
Other [Member]
Segment Reporting Information [Line Items]
Sales	$ 8,593	$ 4,080	$ 18,437	$ 12,865