Ultra Clean (UCTT) 10-Q 8 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 29, 2017	Oct. 27, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 29, 2017
Document Fiscal Year Focus	2,017
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	--12-29
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		33,627,343

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Current assets:
Cash and cash equivalents	$ 65,939	$ 52,465
Accounts receivable, net of allowance of $44 and $65, respectively	107,662	74,663
Inventories	165,303	103,861
Prepaid expenses and other	11,460	6,461
Total current assets	350,364	237,450
Equipment and leasehold improvements, net	28,943	18,858
Goodwill	85,248	85,248
Purchased intangibles, net	33,331	37,024
Deferred tax assets, net	1,098	1,355
Other non-current assets	1,769	762
Total assets	500,753	380,697
Current liabilities:
Bank borrowings	15,518	16,819
Accounts payable	130,539	71,189
Accrued compensation and related benefits	12,510	7,904
Deferred rent, current portion	661	634
Other current liabilities	11,020	4,515
Total current liabilities	170,248	101,061
Bank borrowings, net of current portion	41,810	50,931
Deferred tax liability	9,607	9,917
Deferred rent and other liabilities	2,408	2,657
Total liabilities	224,073	164,566
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; 33,627,343 and 32,956,285 shares issued and outstanding, in 2017 and 2016, respectively	34	33
Additional paid-in capital	186,159	181,781
Common shares held in treasury, at cost, 601,944 shares in 2017 and 2016, respectively	(3,337)	(3,337)
Retained earnings	92,273	38,037
Accumulated other comprehensive gain (loss)	1,551	(383)
Total stockholders’ equity	276,680	216,131
Total liabilities and stockholders’ equity	$ 500,753	$ 380,697

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Statement Of Financial Position [Abstract]
Account receivable, allowance	$ 44	$ 65
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	33,627,343	32,956,285
Common stock, shares outstanding	33,627,343	32,956,285
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. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Income Statement [Abstract]
Sales	$ 242,610	$ 146,154	$ 675,465	$ 388,214
Cost of goods sold	199,914	122,663	551,903	331,132
Gross profit	42,696	23,491	123,562	57,082
Operating expenses:
Research and development	2,722	2,447	8,402	7,082
Sales and marketing	3,662	2,819	10,064	8,537
General and administrative	13,050	11,525	37,656	31,742
Total operating expenses	19,434	16,791	56,122	47,361
Income from operations	23,262	6,700	67,440	9,721
Interest and other income (expense), net	(19)	(1,336)	(2,077)	(3,263)
Income before provision for income taxes	23,243	5,364	65,363	6,458
Income tax provision	3,527	2,750	11,127	6,360
Net income	$ 19,716	$ 2,614	$ 54,236	$ 98
Net income per share:
Basic	$ 0.59	$ 0.08	$ 1.63	$ 0
Diluted	$ 0.57	$ 0.08	$ 1.59	$ 0
Shares used in computing net income per share:
Basic	33,540	32,759	33,342	32,544
Diluted	34,360	33,100	34,216	32,887

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 19,716	$ 2,614	$ 54,236	$ 98
Other comprehensive income:
Change in cumulative translation adjustment	312	50	1,001	125
Cash flow hedges:
Change in fair value of derivatives	333	27	1,026	(101)
Adjustment for net gain (loss) realized and included in net income	(100)	20	(93)	71
Total change in unrealized gain (loss) on derivative instruments	233	47	933	(30)
Other comprehensive income	545	97	1,934	95
Comprehensive income	$ 20,261	$ 2,711	$ 56,170	$ 193

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016
Cash flows from operating activities:
Net income	$ 54,236	$ 98
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,895	4,242
Amortization of finite-lived intangibles	3,693	4,318
Amortization of debt issuance costs	115	114
Stock-based compensation	5,059	4,040
Change in the fair value of the contingent earn out	(278)	1,405
Excess tax benefit from stock-based compensation		771
Loss in the disposal of fixed assets	72
Changes in assets and liabilities
Accounts receivable	(32,387)	(6,567)
Inventories	(60,484)	(16,185)
Prepaid expenses and other	(4,386)	1,249
Deferred income taxes	(224)	1,276
Other non-current assets	(486)	(26)
Accounts payable	57,695	12,342
Accrued compensation and related benefits	4,514	443
Income taxes payable	4,614	450
Other liabilities	1,978	1,412
Net cash provided by operating activities	37,626	9,382
Cash flows from investing activities:
Purchases of equipment and leasehold improvements	(12,534)	(5,460)
Disposal of equipment and leasehold improvements		34
Net cash used for investing activities	(12,534)	(5,426)
Cash flows from financing activities:
Proceeds from bank borrowings	8,172	4,523
Proceeds from issuance of common stock	1,689	500
Principal payments on bank borrowings	(19,228)	(11,016)
Excess tax benefit from stock-based compensation		(771)
Employees’ taxes paid upon vesting of restricted stock units	(2,369)
Net cash used for financing activities	(11,736)	(6,764)
Effect of exchange rate changes on cash and cash equivalents	118	(25)
Net increase (decrease) in cash and cash equivalents	13,474	(2,833)
Cash and cash equivalents at beginning of period	52,465	50,103
Cash and cash equivalents at end of period	65,939	47,270
Supplemental cash flow information:
Income taxes paid	6,860	2,988
Income tax refunds	25	591
Interest paid	3,409	1,920
Non-cash investing activities:
Restricted stock issued	11,778	3,690
Equipment and leasehold improvements purchased included in accounts payable	$ 1,514	$ 483

Organization and Significant Ac

Organization and Significant Accounting Policies	9 Months Ended
	Sep. 29, 2017
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. 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 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 our 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 expands 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. In addition, the Company routinely handles major volume and design changes during the manufacturing process and provides equipment manufacturers flexibility when responding to dynamic demand changes. 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, UCME, UCAP, Marchi and Miconex. The Company’s international sales represented 54.4% and 49.7% of total sales for the three months ended September 29, 2017 and September 23, 2016, respectively and 52.8% and 46.5% of total sales for the nine months ended September 29, 2017 and September 23, 2016, 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 30, 2016 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, Miconex, 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 translation 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Lam Research Corporation 59.1 % 49.5 % 58.3 % 53.5 % Applied Materials, Inc. 24.5 30.9 25.7 27.3 Total 83.6 % 80.4 % 84.0 % 80.8 % Two customers’ accounts receivable balances, Lam Research Corporation and Applied Materials, Inc., were individually greater than 10% of accounts receivable as of September 29, 2017 and as of December 30, 2016, and in the aggregate represented approximately 76.7% and 85.0% of accounts receivable, respectively. Fair Value of Measurements — The Company measures its cash equivalents, foreign currency forward contracts, 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 29, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 28 $ — $ 28 $ — Forward contracts $ 1,097 $ — $ 1,097 $ — Other liabilities: Interest rate swap $ 4 $ — $ 4 $ — Contingent earn-out liability $ — $ — $ — $ — Fair Value Measurement at Reporting Date Using Description December 30, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 15 $ — $ 15 $ — Other liabilities: Interest rate swap $ 6 $ — $ 6 $ — Contingent earn-out liability $ 278 $ — $ — $ 278 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. Internal use software — Direct costs incurred to develop software for internal use are capitalized and amortized over an estimated useful life of three or five years. Costs related to the maintenance of internal use software are expensed as incurred. Capitalized internal use software is included in computer equipment and software. Construction in progress — 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. Construction in progress currently includes capitalized costs related to the Company’s new enterprise reporting system implementation project. 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 29, 2017. The determination of the Company’s tax provision is subject to judgments and estimates. 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. 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 operating 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 29, 2017: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 30, 2016 136,459 $ 13.15 0.57 $ 135 Granted — Exercised (113,362 ) 13.96 Cancelled (13,825 ) 14.56 Outstanding at September 29, 2017 9,272 $ 1.17 1.49 $ 273 Options exercisable at September 29, 2017 9,272 $ 1.17 1.49 $ 273 There were no options granted by the Company during either of the nine months ended September 29, 2017 and September 23, 2016. As of September 29, 2017, 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 29, 2017, the Company granted 353,880 RSUs, with a weighted average fair value of $22.62 per share, and granted 18,750 performance stock units with a weighted average fair value of $20.24 per share. During the second quarter ended June 30, 2017, the Company granted 185,752 RSUs, with a weighted average fair value of $19.80 per share, and granted 108,498 performance stock units with a weighted average fair value of $19.80 per share. There were no RSUs and PSUs granted during the quarter ended March 31, 2017. During the nine months ended September 29, 2017, 145,023 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 552,690 shares. As of September 29, 2017, approximately $13.1 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 29, 2017, a total of 1,715,845 RSUs and PSUs remain outstanding with an aggregate intrinsic value of $50.9 million and a weighted average remaining contractual term of 1.2 years. Restricted Stock Awards — As of September 29, 2017, a total of 52,500 RSAs were outstanding. The total unamortized expense of the Company’s unvested restricted stock awards as of September 29, 2017, was $0.8 million. The following table summarizes the Company’s RSU and RSA activity for the nine months ended September 29, 2017: Shares Aggregate Fair Value (in thousands) Unvested restricted stock units and restricted stock awards at December 30, 2016 1,757,507 $ 16,466 Granted 719,380 Vested (705,213 ) Forfeited (55,829 ) Unvested restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932 Vested and expected to vest restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Cost of sales (1) $ 395 $ 362 $ 996 $ 828 Research and development 77 1,277 177 1,405 Sales and marketing 190 76 411 253 General and administrative 1,635 142 3,475 1,554 2,297 1,857 5,059 4,040 Income tax benefit (349 ) (935 ) (860 ) (3,979 ) Stock-based compensation expense, net of tax $ 1,948 $ 922 $ 4,199 $ 61 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 29, 2017 and September 23, 2016 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, which is when the Company plans to adopt this standard. The Company performed an assessment of the impact of these new accounting standards on its consolidated financial statements by outlining all revenue generating activities, mapping those activities to deliverables and tracing those deliverables to the standard. As a result, the Company does not believe that the adoption of this guidance will have a material impact on its consolidated financial statements and on its internal control over financial reporting. The Company plans to use the modified retrospective transition method. The standard requires new substantial disclosures and the Company will continue to evaluate these disclosure requirements. 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 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 Company adopted the amended accounting guidance in the first quarter of 2017 and recognized $1.7 million of previously excluded tax attributes related to stock option windfall deductions and also recognized a corresponding offset to valuation allowance. Forfeitures will continue to be estimated consistent with the Company's existing accounting policies. The impact to the Company's financial condition, results of operations and cash flows will vary based on, among other factors, the market price of the Company's common stock. In August 2016, the FASB issued an amendment to its accounting guidance related to the classification of certain cash receipts and cash payments. The amendment was issued to reduce the diversity in practice in how certain transactions are classified in the statement of cash flows. The amendment will be effective for the Company beginning in its first quarter of fiscal year 2019 with early adoption permitted. The amendment is required to be adopted retrospectively unless it is impracticable. The Company is evaluating the impact of adopting this amendment to its consolidated financial statements. In January 2017, the FASB clarified its guidance to simplify the measurement of goodwill by eliminating the Step 2 impairment test. The new guidance requires companies to perform goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The amendment will be effective for the Company beginning in its first quarter of fiscal year 2021. The amendment is required to be adopted prospectively. Early adoption is permitted. The Company is evaluating the impact of adopting this amendment to its consolidated financial statements. In January 2017, the FASB clarified its guidance on the definition of a business in accounting for transactions when determining whether they represent acquisitions or disposals of assets or of a business. The amendment will In August

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 29, 2017
Investments All Other Investments [Abstract]
Financial Instruments	2. Financial Instruments Derivative Financial Instruments The Company utilizes foreign currency forward contracts with a local financial institution in the Czech Republic to reduce the risk that its cash flows and earnings of its Miconex subsidiary will be adversely affected by foreign currency exchange rate fluctuations and 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 1.24%, as of September 29, 2017. This interest rate swap effectively locks in a fixed interest rate of 3.74% on $9.3 million of the $13.3 million term loan as of September 29, 2017, with a decreasing notional amount based on prorated quarterly principal payments over the remaining period of the term loan. In 2017, Miconex entered into foreign currency forward contracts to hedge certain forecasted costs and expenses transactions denominated in currencies other than Miconex’s local currency. The notional principal of these contracts was approximately $16.0 million as of September 29, 2017. These contracts have maturities of 36 months or less. 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) and/or to cost of goods sold 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 29, 2017, the effective portion of the Company’s cash flow hedge before tax effect was $1.1 million, of which $0.6 million is expected to be reclassified from AOCI into earnings within the next 12 months. Non-Designated Derivatives The Miconex interest rate swap to convert the variable interest rates on Miconex debt to fixed rates with a total notional amount of $0.3 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 29, 2017 and December 30, 2016. September 29, 2017 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative assets and liabilities: Level 2: Forward contracts Prepaid expenses and other $ 595 $ — $ 595 Interest rate swap Other non-current assets $ 28 $ $ 28 Forward contracts Other non-current assets $ 502 $ — $ 502 Interest rate swap Deferred rent and other liabilities $ — $ 4 $ 4 December 30, 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 assets and liabilities: Level 2: Interest rate swap Other non-current assets $ 15 $ — $ 15 Interest rate swap Deferred rent and other liabilities $ — $ 6 $ 6 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Derivatives in Cash Flow Hedging Relationship Interest rate swap $ (11 ) $ 27 $ — $ (101 ) Forward contracts $ 356 $ — $ 1,197 $ — Gains Reclassified from AOCI into Income (Effective Portion) Three Months Ended Nine Months Ended September 29, September 23, September 29, September 23, Income Statement Location 2017 2016 2017 2016 Derivatives in Cash Flow Hedging Relationship Interest rate swap Interest and other income (expense), net $ (6 ) $ 20 $ (13 ) $ 71 Forward contracts Cost of goods sold $ 106 $ — $ 106 $ — 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 29, 2017 and September 23, 2016. The effect of derivative instruments not designated as hedging instruments on income for the three and nine months ended September 29, 2017 and September 23, 2016 is not significant to the financial statements.

Balance Sheet Information

Balance Sheet Information	9 Months Ended
	Sep. 29, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Information	3. Balance Sheet Information Inventories consisted of the following (in thousands): September 29, December 30, 2017 2016 Raw materials $ 122,835 $ 68,473 Work in process 34,948 26,529 Finished goods 7,520 8,859 Total $ 165,303 $ 103,861 Equipment and leasehold improvements, net, consisted of the following (in thousands): September 29, December 30, 2017 2016 Computer equipment and software $ 11,557 $ 11,135 Furniture and fixtures 3,139 3,118 Machinery and equipment 19,227 17,016 Leasehold improvements 19,310 16,838 Accumulated depreciation (37,523 ) (33,825 ) 15,710 14,282 Construction in progress 13,233 4,576 Total $ 28,943 $ 18,858

Acquisition Earn-out

Acquisition Earn-out	9 Months Ended
	Sep. 29, 2017
Business Combinations [Abstract]
Acquisition Earn-out	4. Acquisition Earn-out On July 31, 2015, the Company acquired 100% of the shareholding interest of Miconex. 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. In 2016, Miconex achieved the specified performance targets for the first year and was paid the maximum of $2.0 million of the $4.0 million potential cash earn-out. The fair value of the earn-out payments was determined by 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 fiscal year 2017, the Company reassessed the fair value of the earn-out payments, decreasing the fair value from $0.3 million as of December 30, 2016 to nil as of September 29, 2017. Miconex failed to achieve the specified performance target for the second year. The decrease of $0.3 million was recorded as other income in the Condensed Consolidated Statements of Operations.

Goodwill and Purchased Intangib

Goodwill and Purchased Intangible Assets	9 Months Ended
	Sep. 29, 2017
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 29, 2017 December 30, 2016 Intangible Intangible Goodwill Assets Total Goodwill Assets Total Carrying amount $ 85,248 $ 33,331 $ 118,579 $ 85,248 $ 37,024 $ 122,272 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 29, 2017 As of December 30, 2016 Gross Gross Carrying Accumulated Carrying Carrying Accumulated Carrying Useful Amount Amortization Value Amount Amortization Value Life AIT Customer relationships $ 19,000 $ (17,763 ) $ 1,237 $ 19,000 $ (17,058 ) $ 1,942 7 Tradename 1,900 (1,900 ) — 1,900 (1,900 ) — 6 Intellectual property/know-how 1,600 (1,200 ) 400 1,600 (1,029 ) 571 7 Marchi Customer relationships 9,900 (2,640 ) 7,260 9,900 (1,898 ) 8,002 10 Tradename 1,170 (603 ) 567 1,170 (443 ) 727 6 Intellectual property/know-how 12,300 (3,678 ) 8,622 12,300 (2,643 ) 9,657 8-12 Miconex Customer relationships 8,800 (2,542 ) 6,258 8,800 (1,662 ) 7,138 7.5 UCT Tradename 8,987 — 8,987 8,987 — 8,987 * Total $ 63,657 $ (30,326 ) $ 33,331 $ 63,657 $ (26,633 ) $ 37,024 * 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 10 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 $1.2 million and $1.4 million for the three months ended September 29, 2017 and September 23, 2016, respectively. Amortization expense is charged to general and administrative expense. As of September 29, 2017, future estimated amortization expense is expected to be as follows (in thousands): Amortization Expense 2017 (remaining in year) $ 1,231 2018 4,582 2019 4,210 2020 3,682 2021 3,554 Thereafter 7,085 Total $ 24,344

Borrowing Arrangements

Borrowing Arrangements	9 Months Ended
	Sep. 29, 2017
Debt Disclosure [Abstract]
Borrowing Arrangements	6. Borrowing Arrangements The Company has credit facilities in the U.S. and Czech Republic that expire on February 2, 2019 and March 31, 2020, respectively. The Company and certain of its subsidiaries have agreed to secure all of their obligations under a credit agreement (the “Credit Agreement”) by granting a first priority lien in substantially all of their respective personal property assets (subject to certain exceptions and limitations). As of September 29, 2017, the outstanding amounts under the U.S. Term Loan and Revolving Credit facility were $13.3 million and $39.9 million, respectively, gross of unamortized debt issuance costs of $0.2 million. The aggregate principal amount of the Revolving Credit facility is $40.0 million. As of September 29, 2017, interest rates on the outstanding U.S. Term Loan and Revolving Credit facility were 3.99% and 4.25%, respectively. In order to manage interest rate risk on the variable component of the Term Loan, the Company entered into an interest rate swap 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 1.24%, as of September 29, 2017. This interest rate swap effectively locks in a fixed interest rate of 3.74% on $9.3 million of the $13.3 million term loan balance outstanding as of September 29, 2017. The Company is required to maintain certain financial covenants including a consolidated charge coverage ratio (as defined in the Credit Agreement) of at least 1.25 to 1.00, a consolidated leverage ratio (as defined in the Credit Agreement) no greater than 3.5 to 1.00 and a minimum 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 29, 2017. 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% 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% 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 the Company from declaring or paying any cash dividends. In conjunction with the acquisition of Miconex in July 2015, the Company has a separate 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 8.3 million euros. The credit agreement requires Miconex to maintain certain financial covenants, including a debt-to-earnings-before-interest-depreciation-and-amortization ratio no greater than 3.00 to 1.00 and an equity ratio of at least 15%. As of September 29, 2017, Miconex was in compliance with all of its covenants. As of September 29, 2017, Miconex had outstanding amounts under the term loan and revolving credit facility of 0.3 million euros (approximately $0.4 million) and 3.3 million euros (approximately $3.9 million), respectively, for a total of $4.3 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 2017 to 2020. As of September 29, 2017, the Company’s total bank debt was $57.3 million, and the Company has $0.1 million and 4.9 million euros (approximately $5.8 million) available to borrow on its revolving loans in the U.S. and Czech Republic, respectively. 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 facilities 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 facilities.

Income Tax

Income Tax	9 Months Ended
	Sep. 29, 2017
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 29, 2017 were $3.5 million and 15.2% and $11.1 million and 17.0%, respectively compared to $2.8 million and 51.3% and $6.4 million and 98.5%, respectively for the three and nine months ended September 23, 2016. The change in respective rates reflects, primarily, changes in the geographic mix of worldwide earnings and financial results, including the impact of income and losses in jurisdictions with full federal and state valuation allowances for the three and nine months ended September 29, 2017 compared to the impact of losses in jurisdictions with full federal and state valuation allowances for the three and nine months ended September 23, 2016. Company management continuously evaluates the need for a valuation allowance and, as of September 29, 2017, 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 adopted Accounting Standards Update 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 29, 2017, the Company had undistributed earnings of foreign subsidiaries that are indefinitely invested outside of the U.S. of approximately $158.0 million. It is not practicable to determine the income tax liability that might be incurred if these earnings were to be distributed. The Company’s gross liability for unrecognized tax benefits as of September 29, 2017 and September 23, 2016 was $0.3 million and $0.4 million, respectively. Although it is possible some of the unrecognized tax benefits could be settled within the next twelve months, the Company cannot reasonably estimate the outcome at this time.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 29, 2017
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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Numerator: Net income $ 19,716 $ 2,614 $ 54,236 $ 98 Denominator: Shares used in computation — basic: Weighted average common shares outstanding 33,540 32,759 33,342 32,544 Shares used in computation — diluted: Shares used in computing basic net income per share 33,540 32,759 33,342 32,544 Dilutive effect of common shares outstanding subject to repurchase 813 313 856 305 Dilutive effect of options outstanding 7 28 18 38 Weighted average shares used in computing diluted net income per share 34,360 33,100 34,216 32,887 Net income per share — basic $ 0.59 $ 0.08 $ 1.63 $ 0.00 Net income per share — diluted $ 0.57 $ 0.08 $ 1.59 $ 0.00 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 options for the three and nine month periods ended September 23, 2016, respectively and none for the three and nine month periods ended September 29, 2017.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 29, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies The Company had commitments to purchase inventory totaling approximately $169.2 million at September 29, 2017. The Company leases properties domestically in Hayward, California, Austin, 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 2023. As of September 29, 2017, future minimum payments under these operating leases were as follows (in thousands): Fiscal Year 2017 (remaining in year) $ 1,858 2018 6,767 2019 5,214 2020 4,836 2021 4,344 Thereafter 3,712 Total minimum lease payments $ 26,731 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.

Geographical Information

Geographical Information	9 Months Ended
	Sep. 29, 2017
Geographical Information [Abstract]
Geographical Information	10. Geographical 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 United States $ 138,866 $ 83,296 $ 372,571 $ 217,026 China 6,834 6,961 24,947 11,593 Singapore 73,427 39,310 207,477 115,353 Austria 6,132 7,994 25,844 25,805 Other 17,351 8,593 44,626 18,437 $ 242,610 $ 146,154 $ 675,465 $ 388,214 At September 29, 2017, approximately $9.9 million and $1.6 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 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.

Organization and Significant 17

Organization and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 29, 2017
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 30, 2016 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 , Miconex, 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 translation 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Lam Research Corporation 59.1 % 49.5 % 58.3 % 53.5 % Applied Materials, Inc. 24.5 30.9 25.7 27.3 Total 83.6 % 80.4 % 84.0 % 80.8 % Two customers’ accounts receivable balances, Lam Research Corporation and Applied Materials, Inc., were individually greater than 10% of accounts receivable as of September 29, 2017 and as of December 30, 2016, and in the aggregate represented approximately 76.7% and 85.0% of accounts receivable, respectively.
Fair Value of Measurements	Fair Value of Measurements — The Company measures its cash equivalents, foreign currency forward contracts, 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 29, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 28 $ — $ 28 $ — Forward contracts $ 1,097 $ — $ 1,097 $ — Other liabilities: Interest rate swap $ 4 $ — $ 4 $ — Contingent earn-out liability $ — $ — $ — $ — Fair Value Measurement at Reporting Date Using Description December 30, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 15 $ — $ 15 $ — Other liabilities: Interest rate swap $ 6 $ — $ 6 $ — Contingent earn-out liability $ 278 $ — $ — $ 278
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, net	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.
Internal use software	Internal use software — Direct costs incurred to develop software for internal use are capitalized and amortized over an estimated useful life of three or five years. Costs related to the maintenance of internal use software are expensed as incurred. Capitalized internal use software is included in computer equipment and software.
Construction in Progress	Construction in progress — 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. Construction in progress currently includes capitalized costs related to the Company’s new enterprise reporting system implementation project.
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 29, 2017. The determination of the Company’s tax provision is subject to judgments and estimates. 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.
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 operating 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 29, 2017: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 30, 2016 136,459 $ 13.15 0.57 $ 135 Granted — Exercised (113,362 ) 13.96 Cancelled (13,825 ) 14.56 Outstanding at September 29, 2017 9,272 $ 1.17 1.49 $ 273 Options exercisable at September 29, 2017 9,272 $ 1.17 1.49 $ 273 There were no options granted by the Company during either of the nine months ended September 29, 2017 and September 23, 2016. As of September 29, 2017, 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 29, 2017, the Company granted 353,880 RSUs, with a weighted average fair value of $22.62 per share, and granted 18,750 performance stock units with a weighted average fair value of $20.24 per share. During the second quarter ended June 30, 2017, the Company granted 185,752 RSUs, with a weighted average fair value of $19.80 per share, and granted 108,498 performance stock units with a weighted average fair value of $19.80 per share. There were no RSUs and PSUs granted during the quarter ended March 31, 2017. During the nine months ended September 29, 2017, 145,023 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 552,690 shares. As of September 29, 2017, approximately $13.1 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 29, 2017, a total of 1,715,845 RSUs and PSUs remain outstanding with an aggregate intrinsic value of $50.9 million and a weighted average remaining contractual term of 1.2 years. Restricted Stock Awards — As of September 29, 2017, a total of 52,500 RSAs were outstanding. The total unamortized expense of the Company’s unvested restricted stock awards as of September 29, 2017, was $0.8 million. The following table summarizes the Company’s RSU and RSA activity for the nine months ended September 29, 2017: Shares Aggregate Fair Value (in thousands) Unvested restricted stock units and restricted stock awards at December 30, 2016 1,757,507 $ 16,466 Granted 719,380 Vested (705,213 ) Forfeited (55,829 ) Unvested restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932 Vested and expected to vest restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932 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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Cost of sales (1) $ 395 $ 362 $ 996 $ 828 Research and development 77 1,277 177 1,405 Sales and marketing 190 76 411 253 General and administrative 1,635 142 3,475 1,554 2,297 1,857 5,059 4,040 Income tax benefit (349 ) (935 ) (860 ) (3,979 ) Stock-based compensation expense, net of tax $ 1,948 $ 922 $ 4,199 $ 61 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 29, 2017 and September 23, 2016 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, which is when the Company plans to adopt this standard. The Company performed an assessment of the impact of these new accounting standards on its consolidated financial statements by outlining all revenue generating activities, mapping those activities to deliverables and tracing those deliverables to the standard. As a result, the Company does not believe that the adoption of this guidance will have a material impact on its consolidated financial statements and on its internal control over financial reporting. The Company plans to use the modified retrospective transition method. The standard requires new substantial disclosures and the Company will continue to evaluate these disclosure requirements. 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 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 Company adopted the amended accounting guidance in the first quarter of 2017 and recognized $1.7 million of previously excluded tax attributes related to stock option windfall deductions and also recognized a corresponding offset to valuation allowance. Forfeitures will continue to be estimated consistent with the Company's existing accounting policies. The impact to the Company's financial condition, results of operations and cash flows will vary based on, among other factors, the market price of the Company's common stock. In August 2016, the FASB issued an amendment to its accounting guidance related to the classification of certain cash receipts and cash payments. The amendment was issued to reduce the diversity in practice in how certain transactions are classified in the statement of cash flows. The amendment will be effective for the Company beginning in its first quarter of fiscal year 2019 with early adoption permitted. The amendment is required to be adopted retrospectively unless it is impracticable. The Company is evaluating the impact of adopting this amendment to its consolidated financial statements. In January 2017, the FASB clarified its guidance to simplify the measurement of goodwill by eliminating the Step 2 impairment test. The new guidance requires companies to perform goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The amendment will be effective for the Company beginning in its first quarter of fiscal year 2021. The amendment is required to be adopted prospectively. Early adoption is permitted. The Company is evaluating the impact of adopting this amendment to its consolidated financial statements. In January 2017, the FASB clarified its guidance on the definition of a business in accounting for transactions when determining whether they represent acquisitions or disposals of assets or of a business. The amendment will In August

Organization and Significant 18

Organization and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 29, 2017
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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Lam Research Corporation 59.1 % 49.5 % 58.3 % 53.5 % Applied Materials, Inc. 24.5 30.9 25.7 27.3 Total 83.6 % 80.4 % 84.0 % 80.8 %
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 29, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 28 $ — $ 28 $ — Forward contracts $ 1,097 $ — $ 1,097 $ — Other liabilities: Interest rate swap $ 4 $ — $ 4 $ — Contingent earn-out liability $ — $ — $ — $ — Fair Value Measurement at Reporting Date Using Description December 30, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets: Interest rate swap $ 15 $ — $ 15 $ — Other liabilities: Interest rate swap $ 6 $ — $ 6 $ — Contingent earn-out liability $ 278 $ — $ — $ 278
Schedule of Option Activity	Stock option activity for the nine months ended September 29, 2017: Shares Weighted Average Exercise Price Weighted Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 30, 2016 136,459 $ 13.15 0.57 $ 135 Granted — Exercised (113,362 ) 13.96 Cancelled (13,825 ) 14.56 Outstanding at September 29, 2017 9,272 $ 1.17 1.49 $ 273 Options exercisable at September 29, 2017 9,272 $ 1.17 1.49 $ 273
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 29, 2017: Shares Aggregate Fair Value (in thousands) Unvested restricted stock units and restricted stock awards at December 30, 2016 1,757,507 $ 16,466 Granted 719,380 Vested (705,213 ) Forfeited (55,829 ) Unvested restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932 Vested and expected to vest restricted stock units and restricted stock awards at September 29, 2017 1,715,845 $ 50,932
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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Cost of sales (1) $ 395 $ 362 $ 996 $ 828 Research and development 77 1,277 177 1,405 Sales and marketing 190 76 411 253 General and administrative 1,635 142 3,475 1,554 2,297 1,857 5,059 4,040 Income tax benefit (349 ) (935 ) (860 ) (3,979 ) Stock-based compensation expense, net of tax $ 1,948 $ 922 $ 4,199 $ 61 (1) Stock-based compensation expenses capitalized in inventory for the three and nine months ended September 29, 2017 and September 23, 2016 were not significant.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 29, 2017
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 29, 2017 and December 30, 2016. September 29, 2017 Fair Value of Fair Value of Derivatives Derivatives Not Balance Sheet Designated as Designated as Total Location Hedge Instruments Hedge Instruments Fair Value Derivative assets and liabilities: Level 2: Forward contracts Prepaid expenses and other $ 595 $ — $ 595 Interest rate swap Other non-current assets $ 28 $ $ 28 Forward contracts Other non-current assets $ 502 $ — $ 502 Interest rate swap Deferred rent and other liabilities $ — $ 4 $ 4 December 30, 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 assets and liabilities: Level 2: Interest rate swap Other non-current assets $ 15 $ — $ 15 Interest rate swap Deferred rent and other liabilities $ — $ 6 $ 6
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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Derivatives in Cash Flow Hedging Relationship Interest rate swap $ (11 ) $ 27 $ — $ (101 ) Forward contracts $ 356 $ — $ 1,197 $ — Gains Reclassified from AOCI into Income (Effective Portion) Three Months Ended Nine Months Ended September 29, September 23, September 29, September 23, Income Statement Location 2017 2016 2017 2016 Derivatives in Cash Flow Hedging Relationship Interest rate swap Interest and other income (expense), net $ (6 ) $ 20 $ (13 ) $ 71 Forward contracts Cost of goods sold $ 106 $ — $ 106 $ —

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	9 Months Ended
	Sep. 29, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Inventories	Inventories consisted of the following (in thousands): September 29, December 30, 2017 2016 Raw materials $ 122,835 $ 68,473 Work in process 34,948 26,529 Finished goods 7,520 8,859 Total $ 165,303 $ 103,861
Equipment and Leasehold Improvements, Net	Equipment and leasehold improvements, net, consisted of the following (in thousands): September 29, December 30, 2017 2016 Computer equipment and software $ 11,557 $ 11,135 Furniture and fixtures 3,139 3,118 Machinery and equipment 19,227 17,016 Leasehold improvements 19,310 16,838 Accumulated depreciation (37,523 ) (33,825 ) 15,710 14,282 Construction in progress 13,233 4,576 Total $ 28,943 $ 18,858

Goodwill and Purchased Intang21

Goodwill and Purchased Intangible Assets (Tables)	9 Months Ended
	Sep. 29, 2017
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 29, 2017 December 30, 2016 Intangible Intangible Goodwill Assets Total Goodwill Assets Total Carrying amount $ 85,248 $ 33,331 $ 118,579 $ 85,248 $ 37,024 $ 122,272
Details of Purchased Intangible Assets	Details of purchased intangible assets were as follows (in thousands): As of September 29, 2017 As of December 30, 2016 Gross Gross Carrying Accumulated Carrying Carrying Accumulated Carrying Useful Amount Amortization Value Amount Amortization Value Life AIT Customer relationships $ 19,000 $ (17,763 ) $ 1,237 $ 19,000 $ (17,058 ) $ 1,942 7 Tradename 1,900 (1,900 ) — 1,900 (1,900 ) — 6 Intellectual property/know-how 1,600 (1,200 ) 400 1,600 (1,029 ) 571 7 Marchi Customer relationships 9,900 (2,640 ) 7,260 9,900 (1,898 ) 8,002 10 Tradename 1,170 (603 ) 567 1,170 (443 ) 727 6 Intellectual property/know-how 12,300 (3,678 ) 8,622 12,300 (2,643 ) 9,657 8-12 Miconex Customer relationships 8,800 (2,542 ) 6,258 8,800 (1,662 ) 7,138 7.5 UCT Tradename 8,987 — 8,987 8,987 — 8,987 * Total $ 63,657 $ (30,326 ) $ 33,331 $ 63,657 $ (26,633 ) $ 37,024 * 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 29, 2017, future estimated amortization expense is expected to be as follows (in thousands): Amortization Expense 2017 (remaining in year) $ 1,231 2018 4,582 2019 4,210 2020 3,682 2021 3,554 Thereafter 7,085 Total $ 24,344

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 29, 2017
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 29, September 23, September 29, September 23, 2017 2016 2017 2016 Numerator: Net income $ 19,716 $ 2,614 $ 54,236 $ 98 Denominator: Shares used in computation — basic: Weighted average common shares outstanding 33,540 32,759 33,342 32,544 Shares used in computation — diluted: Shares used in computing basic net income per share 33,540 32,759 33,342 32,544 Dilutive effect of common shares outstanding subject to repurchase 813 313 856 305 Dilutive effect of options outstanding 7 28 18 38 Weighted average shares used in computing diluted net income per share 34,360 33,100 34,216 32,887 Net income per share — basic $ 0.59 $ 0.08 $ 1.63 $ 0.00 Net income per share — diluted $ 0.57 $ 0.08 $ 1.59 $ 0.00

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 29, 2017
Commitments And Contingencies Disclosure [Abstract]
Summary of Future Minimum Payments under Operating Leases	As of September 29, 2017, future minimum payments under these operating leases were as follows (in thousands): Fiscal Year 2017 (remaining in year) $ 1,858 2018 6,767 2019 5,214 2020 4,836 2021 4,344 Thereafter 3,712 Total minimum lease payments $ 26,731

Geographical Information (Table

Geographical Information (Tables)	9 Months Ended
	Sep. 29, 2017
Geographical Information [Abstract]
Revenue by Geographic Area	The following table sets forth revenue by geographic area (in thousands): Three Months Ended Nine Months Ended September 29, September 23, September 29, September 23, 2017 2016 2017 2016 United States $ 138,866 $ 83,296 $ 372,571 $ 217,026 China 6,834 6,961 24,947 11,593 Singapore 73,427 39,310 207,477 115,353 Austria 6,132 7,994 25,844 25,805 Other 17,351 8,593 44,626 18,437 $ 242,610 $ 146,154 $ 675,465 $ 388,214

Organization and Significant 25

Organization and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017CustomerSegment	Sep. 23, 2016	Dec. 30, 2016Customer
Concentration Risk [Line Items]
Number of operating segments			1
Number of reportable segments			1
Minimum [Member]
Concentration Risk [Line Items]
Fiscal year duration			364 days
Useful lives range			3 years
Minimum [Member] | Internal Use Software [Member]
Concentration Risk [Line Items]
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
Maximum [Member] | Internal Use Software [Member]
Concentration Risk [Line Items]
Useful lives range			5 years
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		2
Sales [Member] | International Sales [Member]
Concentration Risk [Line Items]
Concentration percentage	54.40%	49.70%	52.80%	46.50%
Sales [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration percentage	83.60%	80.40%	84.00%	80.80%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Lam Research Corporation and Applied Materials, Inc. [Member]
Concentration Risk [Line Items]
Concentration percentage			76.70%		85.00%

Organization and Significant 26

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. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Concentration Risk [Line Items]
Total	83.60%	80.40%	84.00%	80.80%
Lam Research Corporation [Member]
Concentration Risk [Line Items]
Total	59.10%	49.50%	58.30%	53.50%
Applied Materials, Inc. [Member]
Concentration Risk [Line Items]
Total	24.50%	30.90%	25.70%	27.30%

Organization and Significant 27

Organization and Significant Accounting Policies - Assets or Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Forward Contracts [Member]
Other assets:
Assets measured at fair value	$ 1,097
Interest Rate Swap [Member]
Other assets:
Assets measured at fair value	28	$ 15
Other liabilities:
Liabilities measured at fair value	4	6
Contingent Earn-out Liability [Member]
Other liabilities:
Liabilities measured at fair value		278
Significant Other Observable Inputs (Level 2) [Member] | Forward Contracts [Member]
Other assets:
Assets measured at fair value	1,097
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Swap [Member]
Other assets:
Assets measured at fair value	28	15
Other liabilities:
Liabilities measured at fair value	$ 4	6
Significant Unobservable Inputs (Level 3) [Member] | Contingent Earn-out Liability [Member]
Other liabilities:
Liabilities measured at fair value		$ 278

Organization and Significant 28

Organization and Significant Accounting Policies - Additional Information 1 (Detail) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 29, 2017	Sep. 23, 2016
ASU 2016-09 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Adoption of amended accounting guidance and recognized previously excluded tax attributes related to stock option			$ 1,700,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				3 years
Granted stock units	353,880	185,752	0
Weighted average fair value, granted	$ 22.62	$ 19.80
Vested shares withheld to satisfy withholding tax obligations				145,023
Vested shares issued net of tax withholdings				552,690
Stock-based compensation cost, net of estimated forfeitures, recognized				$ 13,100,000
Outstanding restricted stock	1,715,845			1,715,845
Aggregate fair value	$ 50,900,000			$ 50,900,000
Weighted average remaining contractual term (in years)				1 year 2 months 13 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	52,500			52,500
Unamortized expense of company's unvested restricted stock awards	$ 800,000			$ 800,000
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock option grant				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 units	18,750	108,498	0
Weighted average fair value, granted	$ 20.24	$ 19.80
Stock-based compensation cost, net of estimated forfeitures, recognized				$ 13,100,000
Outstanding restricted stock	1,715,845			1,715,845
Aggregate fair value	$ 50,900,000			$ 50,900,000
Weighted average remaining contractual term (in years)				1 year 2 months 13 days
Performance Stock Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, years				2 years

Organization and Significant 29

Organization and Significant Accounting Policies - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 29, 2017	Dec. 30, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Shares, Beginning balance	136,459
Granted, Shares	0
Exercised, Shares	(113,362)
Cancelled, Shares	(13,825)
Outstanding, Shares, Ending balance	9,272	136,459
Options exercisable, Shares	9,272
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 13.15
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	13.96
Canceled, Weighted Average Exercise Price	14.56
Weighted Average Exercise Price, Outstanding, Ending balance	1.17	$ 13.15
Options exercisable, Weighted Average Exercise Price	$ 1.17
Weighted Average Remaining Contractual Life (years), Outstanding	1 year 5 months 27 days	6 months 25 days
Weighted Average Remaining Contractual Life (years), Options exercisable	1 year 5 months 27 days
Aggregate Intrinsic Value, Outstanding	$ 273	$ 135
Aggregate Intrinsic Value, Options exercisable	$ 273

Organization and Significant 30

Organization and Significant Accounting Policies - Summary of Restricted Stock Unit and Restricted Stock Award Activity (Detail) - Restricted Stock Unit and Restricted Stock Award [Member] $ in Thousands	9 Months Ended
	Sep. 29, 2017USD ($)shares	Dec. 30, 2016USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units and restricted stock awards, Number of Shares, Beginning balance	1,757,507
Granted, Number of Shares	719,380
Vested, Number of Shares	(705,213)
Forfeited, Number of Shares	(55,829)
Unvested restricted stock units and restricted stock awards, Number of Shares, Ending balance	1,715,845
Vested and expected to vest restricted stock units and restricted stock awards, Number of Shares	1,715,845
Unvested restricted stock units and restricted stock awards, Aggregate Intrinsic Value | $	$ 50,932	$ 16,466
Vested and expected to vest restricted stock units and restricted stock awards, Aggregate Intrinsic Value | $	$ 50,932

Organization and Significant 31

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. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,297	$ 1,857	$ 5,059	$ 4,040
Income tax benefit	(349)	(935)	(860)	(3,979)
Stock-based compensation expense, net of tax	1,948	922	4,199	61
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	395	362	996	828
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	77	1,277	177	1,405
Sales and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	190	76	411	253
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 1,635	$ 142	$ 3,475	$ 1,554

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016	Sep. 30, 2015
Miconex [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Financial Instruments [Line Items]
Non-Designated Derivatives, description			The Miconex interest rate swap to convert the variable interest rates on Miconex debt to fixed rates with a total notional amount of $0.3 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			$ 1,100,000
Cash flow hedge, expected to be reclassified from AOCI into earnings			600,000
Interest Rate Swap [Member] | Miconex [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount	$ 300,000		$ 300,000
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] | Interest Rate Swap [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Debt instrument LIBOR rate					0.99%
Credit Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member] | Term Loan Credit Facility [Member]
Financial Instruments [Line Items]
Debt instrument variable interest rate			1.24%
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] | Foreign Currency Forward Contracts [Member]
Financial Instruments [Line Items]
Derivative instrument, notional amount	$ 16,000,000		$ 16,000,000
Derivatives in Cash Flow Hedging Relationship [Member] | Maximum [Member] | Foreign Currency Forward Contracts [Member]
Financial Instruments [Line Items]
Contracts maturities			36 months
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	$ 13,300,000		$ 13,300,000
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	$ 9,300,000		$ 9,300,000

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments at Gross Fair Value (Detail) - Significant Other Observable Inputs (Level 2) [Member] - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Forward Contracts [Member] | Prepaid Expenses and Other [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, Fair Value of Derivatives Designated as Hedge Instrument	$ 595
Derivative assets, Total Fair Value	595
Forward Contracts [Member] | Other Non-Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, Fair Value of Derivatives Designated as Hedge Instrument	502
Derivative assets, Total Fair Value	502
Interest Rate Swap [Member] | Other Non-Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, Fair Value of Derivatives Designated as Hedge Instrument	28	$ 15
Derivative assets, Total Fair Value	28	15
Interest Rate Swap [Member] | Deferred Rent and Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, Fair Value of Derivatives Not Designated as Hedge Instrument	4	6
Derivative liabilities, Total Fair Value	$ 4	$ 6

Financial Instruments - Effect

Financial Instruments - Effect of Derivative Instruments in Cash Flow Hedging Relationships on Income and Other Comprehensive Income (Detail) - Derivatives in Cash Flow Hedging Relationship [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Recognized in OCI on Derivatives Before Tax Effect (Effective Portion)	$ (11)	$ 27		$ (101)
Interest Rate Swap [Member] | Interest and Other Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains Reclassified from AOCI into Income (Effective Portion)	(6)	$ 20	$ (13)	$ 71
Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Recognized in OCI on Derivatives Before Tax Effect (Effective Portion)	356		1,197
Forward Contracts [Member] | Cost of Goods Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains Reclassified from AOCI into Income (Effective Portion)	$ 106		$ 106

Balance Sheet Information - Sum

Balance Sheet Information - Summary of Inventories (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 122,835	$ 68,473
Work in process	34,948	26,529
Finished goods	7,520	8,859
Total	$ 165,303	$ 103,861

Balance Sheet Information - Equ

Balance Sheet Information - Equipment and Leasehold Improvements, Net (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (37,523)	$ (33,825)
Equipment and leasehold improvements net excluding construction in progress	15,710	14,282
Construction in progress	13,233	4,576
Total	28,943	18,858
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	11,557	11,135
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	3,139	3,118
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	19,227	17,016
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Equipment and leasehold improvements, gross	$ 19,310	$ 16,838

Acquisition Earn-out - Addition

Acquisition Earn-out - Additional Information (Detail) - USD ($)	Jul. 31, 2015	Sep. 29, 2017	Sep. 23, 2016	Dec. 30, 2016
Business Acquisition [Line Items]
Change in the fair value of the contingent earn out		$ (278,000)	$ 1,405,000
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		0		$ 300,000
Business acquisition, potential cash payments period	2 years
Change in the fair value of the contingent earn out		$ (300,000)
Miconex [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business acquisition, potential cash earn-out payments	$ 4,000,000			$ 2,000,000
Miconex [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares of newly issued common stock	500,000

Goodwill and Purchased Intang38

Goodwill and Purchased Intangible Assets - Goodwill and Other Indefinite Lived Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 30, 2016
Intangible Assets Net Including Goodwill [Abstract]
Goodwill	$ 85,248	$ 85,248
Intangible Assets	33,331	37,024
Total	$ 118,579	$ 122,272

Goodwill and Purchased Intang39

Goodwill and Purchased Intangible Assets - Details of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Dec. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, accumulated amortization	$ (30,326)	$ (26,633)
Definite lives intangible assets, net carrying amount	24,344
Intangible Assets, gross carrying value	63,657	63,657
Intangible Assets, net carrying value	33,331	37,024
American Integration Technologies LLC [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	19,000	19,000
Definite lives intangible assets, accumulated amortization	(17,763)	(17,058)
Definite lives intangible assets, net carrying amount	$ 1,237	1,942
Useful Life (in years)	7 years
American Integration Technologies LLC [Member] | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 1,900	1,900
Definite lives intangible assets, 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]
Definite lives intangible assets, gross carrying amount	$ 1,600	1,600
Definite lives intangible assets, accumulated amortization	(1,200)	(1,029)
Definite lives intangible assets, net carrying amount	$ 400	571
Useful Life (in years)	7 years
Marchi Thermal Systems Inc [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 9,900	9,900
Definite lives intangible assets, accumulated amortization	(2,640)	(1,898)
Definite lives intangible assets, net carrying amount	$ 7,260	8,002
Useful Life (in years)	10 years
Marchi Thermal Systems Inc [Member] | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 1,170	1,170
Definite lives intangible assets, accumulated amortization	(603)	(443)
Definite lives intangible assets, net carrying amount	$ 567	727
Useful Life (in years)	6 years
Marchi Thermal Systems Inc [Member] | Intellectual Properties/Know-How [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 12,300	12,300
Definite lives intangible assets, accumulated amortization	(3,678)	(2,643)
Definite lives intangible assets, net carrying amount	$ 8,622	9,657
Marchi Thermal Systems Inc [Member] | Intellectual Properties/Know-How [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life (in 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
Miconex [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 8,800	8,800
Definite lives intangible assets, accumulated amortization	(2,542)	(1,662)
Definite lives intangible assets, net carrying amount	$ 6,258	7,138
Useful Life (in years)	7 years 6 months
Uct | Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite lives intangible assets	$ 8,987	$ 8,987

Goodwill and Purchased Intang40

Goodwill and Purchased Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of finite-lived intangibles	$ 1,200	$ 1,400	$ 3,693	$ 4,318
Minimum [Member] | Trade Name [Member] | American Integration Technologies LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Minimum [Member] | Trade Name [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Minimum [Member] | Customer Relationships [Member] | American Integration Technologies LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Minimum [Member] | Customer Relationships [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Minimum [Member] | Customer Relationships [Member] | Miconex [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Minimum [Member] | Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Minimum [Member] | Intellectual Properties/Know-How [Member] | Miconex [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Maximum [Member] | Trade Name [Member] | American Integration Technologies LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			10 years
Maximum [Member] | Trade Name [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			10 years
Maximum [Member] | Customer Relationships [Member] | American Integration Technologies LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			10 years
Maximum [Member] | Customer Relationships [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Maximum [Member] | Customer Relationships [Member] | Miconex [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Maximum [Member] | Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Maximum [Member] | Intellectual Properties/Know-How [Member] | Miconex [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years

Goodwill and Purchased Intang41

Goodwill and Purchased Intangible Assets - Future Estimated Amortization Expense (Detail) $ in Thousands	Sep. 29, 2017USD ($)
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
2017 (remaining in year)	$ 1,231
2,018	4,582
2,019	4,210
2,020	3,682
2,021	3,554
Thereafter	7,085
Definite lives intangible assets, net carrying amount	$ 24,344

Borrowing Arrangements - Additi

Borrowing Arrangements - Additional Information (Detail)	1 Months Ended	9 Months Ended
	Jul. 31, 2015EUR (€)	Sep. 29, 2017USD ($)	Sep. 29, 2017EUR (€)	Sep. 30, 2015USD ($)
Debt Instrument [Line Items]
Debt Instrument, covenant description		The Company is required to maintain certain financial covenants including a consolidated charge coverage ratio (as defined in the Credit Agreement) of at least 1.25 to 1.00, a consolidated leverage ratio (as defined in the Credit Agreement) no greater than 3.5 to 1.00 and a minimum 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 29, 2017.
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]
Charge coverage ratio for the next fiscal year		1.25%
Required cash balance		$ 35,000,000
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%
U.S. Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 13,300,000
Base rate interest		3.99%
U.S. Term Loan Credit Facility [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative instrument, notional amount				$ 20,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding amounts		$ 39,900,000
Borrowing capacity under credit facility		40,000,000
U.S. Term Loan And Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		200,000
Credit Agreement [Member] | U.S. Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 13,300,000
Credit Agreement [Member] | U.S. Term Loan Credit Facility [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate		1.24%
Derivative instrument, notional amount		$ 9,300,000
Debt instrument LIBOR rate				0.99%
Debt instrument interest rate		3.74%	3.74%
Credit Agreement [Member] | Revolving Credit Facility
Debt Instrument [Line Items]
Base rate interest		4.25%
Credit Agreement [Member] | U.S. [Member]
Debt Instrument [Line Items]
Credit facility expiration date		Feb. 2, 2019
Credit Agreement [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Credit facility expiration date		Mar. 31, 2020
Credit Agreement [Member] | Czech Republic [Member] | Miconex [Member]
Debt Instrument [Line Items]
Debt Instrument, covenant description		The credit agreement requires Miconex to maintain certain financial covenants, including a debt-to-earnings-before-interest-depreciation-and-amortization ratio no greater than 3.00 to 1.00 and an equity ratio of at least 15%. As of September 29, 2017, Miconex was in compliance with all of its covenants.
Debt to earnings before interest depreciation and amortization ratio maximum	300.00%
Equity ratio minimum	15.00%
Bank Debt [Member]
Debt Instrument [Line Items]
Outstanding amount of borrowing classified as long-term debt		$ 57,300,000
Bank Debt [Member] | U.S. [Member] | Revolving Credit Facility
Debt Instrument [Line Items]
Available borrowings under revolving loan		$ 100,000
Bank Debt [Member] | Czech Republic [Member]
Debt Instrument [Line Items]
Debt due date, start year		2,017
Debt due date, end year		2,020
Bank Debt [Member] | Czech Republic [Member] | Miconex [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 4,300,000
Bank Debt [Member] | Czech Republic [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument interest rate		1.30%	1.30%
Bank Debt [Member] | Czech Republic [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument interest rate		2.30%	2.30%
Bank Debt [Member] | Czech Republic [Member] | U.S. Term Loan Credit Facility [Member] | Miconex [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 400,000	€ 300,000
Borrowing capacity under credit facility | €	€ 800,000
Bank Debt [Member] | Czech Republic [Member] | Revolving Credit Facility
Debt Instrument [Line Items]
Available borrowings under revolving loan		5,800,000	4,900,000
Bank Debt [Member] | Czech Republic [Member] | Revolving Credit Facility | Miconex [Member]
Debt Instrument [Line Items]
Outstanding amounts		$ 3,900,000	€ 3,300,000
Bank Debt [Member] | Czech Republic [Member] | Revolving Credit Facility | Maximum [Member] | Miconex [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit facility | €	€ 8,300,000

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016	Dec. 30, 2016
Income Taxes [Line Items]
Income tax provision	$ 3,527	$ 2,750	$ 11,127	$ 6,360
Effective tax rate	15.20%	51.30%	17.00%	98.50%
Undistributed earnings of foreign subsidiaries	$ 158,000		$ 158,000
Gross liability for unrecognized tax benefits	$ 300	$ 400	$ 300	$ 400
ASU 2016-09 [Member] | Federal [Member]
Income Taxes [Line Items]
Excluded windfall deductions recognized as deferred tax asset net					$ 1,600
ASU 2016-09 [Member] | State [Member]
Income Taxes [Line Items]
Excluded windfall deductions recognized as deferred tax asset net					$ 200

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. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Numerator:
Net income	$ 19,716	$ 2,614	$ 54,236	$ 98
Shares used in computation — basic:
Weighted average common shares outstanding	33,540	32,759	33,342	32,544
Shares used in computation — diluted:
Shares used in computing basic net income per share	33,540	32,759	33,342	32,544
Dilutive effect of common shares outstanding subject to repurchase	813	313	856	305
Dilutive effect of options outstanding	7	28	18	38
Weighted average shares used in computing diluted net income per share	34,360	33,100	34,216	32,887
Net income per share — basic	$ 0.59	$ 0.08	$ 1.63	$ 0
Net income per share — diluted	$ 0.57	$ 0.08	$ 1.59	$ 0

Net Income Per Share - Addition

Net Income Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Employee Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	0	174,202	0	187,389

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 29, 2017USD ($)
Long Term Purchase Commitment [Line Items]
Operating lease expiration period	Various dates through 2023
Inventory [Member]
Long Term Purchase Commitment [Line Items]
Purchase commitments	$ 169.2

Commitments and Contingencies47

Commitments and Contingencies - Summary of Future Minimum Payments under Operating Leases (Detail) $ in Thousands	Sep. 29, 2017USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2017 (remaining in year)	$ 1,858
2,018	6,767
2,019	5,214
2,020	4,836
2,021	4,344
Thereafter	3,712
Total minimum lease payments	$ 26,731

Geographical Information - Addi

Geographical Information - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 29, 2017USD ($)Segment	Sep. 23, 2016USD ($)
Revenues From External Customers And Long Lived Assets [Line Items]
Number of operating segments | Segment	1
Number of reportable segments | Segment	1
Other Asia [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived assets | $	$ 9.9	$ 7.4
Czech Republic [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived assets | $	$ 1.6	$ 1.8

Geographical Information - Reve

Geographical Information - Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 23, 2016	Sep. 29, 2017	Sep. 23, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	$ 242,610	$ 146,154	$ 675,465	$ 388,214
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	138,866	83,296	372,571	217,026
China [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	6,834	6,961	24,947	11,593
Singapore [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	73,427	39,310	207,477	115,353
Austria [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	6,132	7,994	25,844	25,805
Other [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Sales	$ 17,351	$ 8,593	$ 44,626	$ 18,437