Ultra Clean (UCTT) 10-Q 1 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 27, 2013	Oct. 29, 2013
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	27-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'UCTT	'
Entity Registrant Name	'ULTRA CLEAN HOLDINGS INC	'
Entity Central Index Key	'0001275014	'
Current Fiscal Year End Date	'--12-27	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	28,583,595

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$65,941	$54,311
Accounts receivable, net of allowance of $5 and $8, respectively	49,728	50,074
Inventory	50,293	53,965
Prepaid expenses and other	7,065	6,769
Total current assets	173,027	165,119
Equipment and leasehold improvements, net	8,756	9,282
Goodwill	55,918	56,662
Purchased intangibles, net	23,235	27,702
Other non-current assets	6,417	7,164
Total assets	267,353	265,929
Current liabilities:	'	'
Bank borrowings	36,706	48,706
Accounts payable	37,770	23,485
Accrued compensation and related benefits	4,161	4,611
Deferred rent, current portion	258	16
Other current liabilities	2,040	2,418
Total current liabilities	80,935	79,236
Long-term debt, net of current portion	19,799	26,934
Deferred rent and other liabilities	3,203	2,979
Total liabilities	103,937	109,149
Commitments and contingencies (See Note 8)	'	'
Stockholders' equity:	'	'
Preferred stock - $0.001 par value, 10,000,000 authorized; none outstanding	'	'
Common stock - $0.001 par value, 90,000,000 authorized; 28,505,955 and 27,910,851 shares issued and outstanding, in 2013 and 2012, respectively	145,763	143,180
Common shares held in treasury, at cost, 601,944 shares in 2013 and 2012	-3,337	-3,337
Retained earnings	20,990	16,937
Total stockholders' equity	163,416	156,780
Total liabilities and stockholders' equity	$267,353	$265,929

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]	'	'
Accounts receivable, allowance	$5	$8
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	28,505,955	27,910,851
Common stock, shares outstanding	28,505,955	27,910,851
Treasury stock, shares	601,944	601,944

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Income Statement [Abstract]	'	'	'	'
Sales	$107,183	$100,849	$317,754	$313,363
Cost of goods sold	91,350	86,526	271,995	269,126
Gross profit	15,833	14,323	45,759	44,237
Operating expenses:	'	'	'	'
Research and development	1,410	1,309	4,156	4,003
Sales and marketing	2,561	1,805	7,344	5,215
General and administrative	8,471	9,812	26,619	22,893
Acquisition costs	'	2,063	'	2,063
Total operating expenses	12,442	14,989	38,119	34,174
Income (loss) from operations	3,391	-666	7,640	10,063
Interest and other income (expense), net	-968	-813	-2,656	-932
Income (loss) before provision for income taxes	2,423	-1,479	4,984	9,131
Income tax provision (benefit)	375	-356	931	2,804
Net income (loss)	$2,048	($1,123)	$4,053	$6,327
Net income (loss) per share:	'	'	'	'
Basic	$0.07	($0.04)	$0.14	$0.25
Diluted	$0.07	($0.04)	$0.14	$0.25
Shares used in computing net income per share:	'	'	'	'
Basic	28,451	27,656	28,265	24,851
Diluted	28,979	27,656	28,879	25,493

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Cash flows from operating activities:	'	'
Net income	$4,053	$6,327
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Loss from disposal of fixed assets	329	'
Depreciation	2,349	2,386
Amortization of intangibles	4,467	1,837
Excess tax benefit from stock-based compensation	-644	-204
Amortization of debt issuance costs	367	114
Stock-based compensation	3,511	3,846
Changes in assets and liabilities:	'	'
Accounts receivable	346	10,814
Inventory	4,516	14,643
Prepaid expenses and other	-296	-1,782
Deferred income taxes net and other non-current assets	747	-189
Accounts payable	14,324	-6,728
Accrued compensation and related benefits	-450	-851
Other liabilities	120	-1,284
Net cash provided by operating activities	33,739	28,929
Cash used in investing activities:	'	'
Purchases of equipment and leasehold improvements	-2,288	-409
Disposal of equipment and leasehold improvements	96	'
AIT acquisition, net of cash acquired	'	-75,325
Net cash used in investing activities	-2,192	-75,734
Cash used in financing activities:	'	'
Proceeds from revolving credit facility	36,000	115,454
Principal payments on revolving credit facility, term loan and capital lease obligations	-55,502	-60,530
Excess tax benefit from stock-based compensation	644	117
Employees' taxes paid upon vesting of restricted stock units	-1,268	-341
Proceeds from issuance of common stock	209	219
Payments of debt issuance costs, equity issuance costs	'	-1,940
Net cash provided by (used in) financing activities	-19,917	52,979
Net increase in cash	11,630	6,174
Cash and cash equivalents at beginning of period	54,311	52,155
Cash and cash equivalents at end of period	65,941	58,329
Cash paid during the period:	'	'
Income taxes paid	1,070	4,472
Income tax refunds	-22	-661
Interest	1,789	800
Non-cash activities:	'	'
Fair value of common shares issued for acquisition	'	29,565
Restricted stock issued	'	4,744
Fixed Asset purchased included in accounts payable	$39	'

Organization_and_Significant_A

Organization and Significant Accounting Policies	9 Months Ended
	Sep. 27, 2013
Accounting Policies [Abstract]	'
Organization and Significant Accounting Policies	'
	1. Organization and Significant Accounting Policies
	Organization — Ultra Clean Holdings, Inc. (the “Company”) is a leading developer and supplier of critical subsystems, primarily for the semiconductor capital equipment industry. The Company also leverages the specialized skill sets required to support semiconductor capital equipment to serve the technologically similar markets in the flat panel, medical, energy and research industries, collectively referred to as “Other Addressed Industries”. The Company develops, designs, prototypes, engineers, manufactures and tests subsystems which are highly specialized and tailored to specific steps in the semiconductor manufacturing process as well as the manufacturing processes in Other Addressed Industries. Revenue is derived from the sale of gas delivery systems and other critical subsystems including chemical mechanical planarization (CMP) subsystems, chemical delivery modules, top-plate assemblies, frame assemblies, process modules and other high level assemblies.
	The Company’s customers are primarily original equipment manufacturers (OEMs) in industries it supports, providing customers complete subsystem solutions that combine the Company’s expertise in design, test, component characterization and highly flexible manufacturing operations with quality control and financial stability. This combination helps the Company to drive down total manufacturing costs, reduce design-to-delivery cycle times and maintain high quality standards for the Company’s customers. The Company believes these characteristics, as well as the Company’s standing as a leading supplier of gas delivery systems and other critical subsystems, place the Company in a strong position to benefit from the demand for subsystem outsourcing.
	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 subsidiaries and have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). This financial information reflects all adjustments which are, in the opinion of the Company, normal, recurring and necessary to present fairly the statements of financial position, results of operations and cash flows 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 28, 2012, balance sheet data was derived from audited financial statements as of that date.
	In July 2012, the Company completed its acquisition of American Integration Technologies LLC (“AIT”). Beginning in the third quarter of fiscal 2012, the acquired business is included in the Company’s consolidated results of operations.
	Principles of Consolidation — The Company’s condensed consolidated financial statements include the accounts of the Company and its subsidiaries and all intercompany accounts and transactions have been eliminated in consolidation.
	Foreign Currency Translation — The Company has reviewed its non-U.S. subsidiaries (of which all of its non-U.S. asset base resides in Asia) that operate in a local currency environment to determine their functional currency by examining how and in what currency each subsidiary generates cash through billings and cash receipts and how and in what currency the subsidiary expends cash through payment of its vendors and payment of its workforce. Also, these subsidiaries’ individual assets and liabilities that are primarily denominated in the local foreign currency are examined for their impact on the Company’s cash flows. All have been determined to have the U.S. dollar as its functional currency. Foreign currency transaction gains and losses are recorded in other income (expense), net.
	Use of Accounting Estimates — The presentation of condensed financial statements in conformity with Generally Accepted Accounting Principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. 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.
	Certain Significant Risks and Uncertainties — The Company operates in a dynamic industry and, accordingly, can be affected by a variety of factors. For example, any of the following areas could have a negative effect on the Company in terms of its future financial position, results of operations or cash flows: the general state of the U.S. and world economies, the highly cyclical nature of the industries the Company serves; the loss of any of a small number of customers; ability to obtain additional financing; inability to meet certain debt covenants; failure to successfully integrate completed acquisitions; ineffectiveness in pursuing acquisition opportunities; regulatory changes; fundamental changes in the technology underlying semiconductor, flat panel, solar and medical device manufacturing processes or manufacturing equipment; the hiring, training and retention of key employees; successful and timely completion of product design efforts; and new product design introductions by competitors.
	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 had significant sales to three customers, each of which accounted for 10% or more of sales for the three months ended September 27, 2013 and September 28, 2012. The Company had significant sales to three customers, each of which accounted for 10% or more of sales for the nine months ended September 27, 2013 and two of which counted for 10% or more of sales for the nine months ended September 28, 2012. Sales to each of these customers as a percentage of total sales were as follows:
			Three months ended						Nine months ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Applied Materials, Inc.			32.9	%		29.4	%		33.1	%		39.6	%
	Lam Research Corporation (1)			37.4	%		27.5	%		33.2	%		34.4	%
	ASM International (2)			10.8	%		19.5	%		13.4	%		—
	Total			81.1	%		76.4	%		79.7	%		74	%
	-1	In June 2012, Lam Research Corporation completed the acquisition of Novellus Systems, Inc., one of the Company’s customers. The sales percentages for Lam Research Corporation for the nine months ended September 28, 2012, reflect the inclusion of sales to Novellus Systems, Inc., from the beginning of fiscal 2012 for comparison purposes.
	-2	Sales to ASM International are the result of the Company’s acquisition of AIT during the third quarter of 2012.
	Three customers’ accounts receivable balances: Applied Materials, Inc., Lam Research Corporation and ASM International were individually greater than 10% of accounts receivable as of September 27, 2013 and as of December 28, 2012, and, in the aggregate, represented approximately 79% and 84%, respectively, of accounts receivable.
	Fair Value of Financial Instruments-The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable and bank borrowings. The carrying value of cash and cash equivalents, accounts receivable and accounts payable approximates their fair value because of their short-term nature.
	The accounting guidance for fair value measurements prioritizes the inputs used in measuring fair value in the following hierarchy:
	Level I — Quoted prices in active markets for identical assets or liabilities,
	Level 2 — Observable inputs other than the Level I prices for similar assets or liabilities; quoted prices in active markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities,
	Level 3 — Unobservable inputs in which there is little or no market data, and that are significant to the fair value of the assets or liabilities.
	The Company’s only financial asset measured at fair value on a recurring basis is an overnight sweep account invested in money market funds which are presented as cash and cash equivalents with a carrying value and fair value of $17.9 million at September 27, 2013, based on Level 2 inputs. The Company’s only financial liability measured at fair value is the amount outstanding under our credit facility. Specifically, the fair value of outstanding borrowings under our term loan was based on level 2 inputs and fair value was determined using quoted prices for similar liabilities in inactive markets and our outstanding borrowings under our revolving credit facility were 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 our long term loan and revolving credit facility.
	Fiscal Year — 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.
	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. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.
	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 consolidated statements of income as income tax expense.
	The determination of the Company’s tax provision is subject to judgments and estimates. The carrying value of the Company’s net deferred tax assets, which is made up primarily of tax deductions, assumes the Company will be able to generate sufficient future income to fully realize these deductions. In determining whether the realization of these deferred tax assets may be impaired, the Company makes judgments with respect to whether it is likely to generate sufficient future taxable income to realize these assets. The Company has a valuation allowance on the deferred tax assets of one of its China subsidiaries in the amount of $851,000 as of September 27, 2013 and December 28, 2012.
	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 tax audits, however, the outcome of tax audits cannot be predicted with certainty.
	Product Warranty — The Company provides a warranty on its products for a period of up to two years and reserves for expected warranty liabilities at the time of sale based on historical activity. The determination of such reserves 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 cost of sales may be required in future periods. Components in the reserve for warranty costs consisted of the following for the periods set forth below (in thousands):
			Nine months ended
			September 27,			September 28,
			2013			2012
	Beginning balance		$	152		$	350
	Change in reserve			70			(4	)
	Warranty claims			(119	)		(112	)
	Ending balance		$	103		$	234
	Revenue Recognition — Product revenue is generally recorded upon shipment. In arrangements which specify title transfer upon delivery, revenue is not recognized until the product is delivered. The Company recognizes revenue when persuasive evidence of an arrangement exists, shipment or delivery, as applicable, 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 (loss) per Share — Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of shares outstanding for the period. Diluted net income (loss) per share is calculated by dividing net income (loss) 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 7 to Condensed Consolidated Financial Statements).
	Comprehensive Income (Loss) — The Company reports by major components and as a single total, the change in its net assets during the period from non-owner sources. Comprehensive income (loss) for all periods presented was the same as net income (loss).
	Segments — The Financial Accounting Standards Board’s (FASB) guidance regarding disclosure about segments in an enterprise and related information establishes standards for the reporting by public business enterprises of information about reportable segments, products and services, geographic areas, and major customers. The method for determining what information to report is based on the manner in which management organizes the reportable segments within the Company for making operational decisions and assessments of financial performance. The Company’s chief operating decision-maker is considered to be the Chief Executive Officer. The Company operates in one reporting segment.
	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, for 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 of the Company. These equity-based awards include stock options, restricted stock awards and restricted stock units which can be either time-based or performance-based. 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 over the awards’ vesting period on a straight-line basis over a weighted average period of four years for stock options (three years for restricted stock units and one year for restricted stock awards) and will be adjusted for subsequent changes in estimated forfeitures and future option grants.
	The Company applies the fair value recognition provisions based on the FASB’s guidance regarding stock-based compensation. The exercise price of each stock option equals the market price of the Company’s stock on the date of grant. The estimated fair value of the Company’s equity-based awards, less expected forfeitures, is amortized over the awards’ vesting periods on a straight-line basis over the applicable vesting period and will be adjusted for subsequent changes in estimated forfeitures and future option grants. Most options are scheduled to vest over four years and expire no later than ten years from the grant date. The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model. The determination of the fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price as well as assumptions regarding a number of complex and subjective variables. These variables include the expected term of the awards; the Company’s expected stock price volatility over the term of the awards, actual and projected employee stock option exercise behaviors, risk-free interest rate and expected dividends. The Company estimates the expected term of share-based awards granted based on the Company’s historical option term experience. The Company estimates the volatility of its common stock based upon the Company’s historical stock price volatility over the length of the expected term of the options. The Company bases the risk-free interest rate that it uses in the option valuation model on U.S. Treasury zero-coupon bond issues with remaining maturities similar to the expected term of the options. The Company does not anticipate paying any cash dividends in the foreseeable future and therefore uses an expected dividend yield of zero in the option valuation model. The Company is required to estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and records share-based compensation expense only for those awards that are expected to vest. The Company also considers, each quarter, whether there have been any significant changes in facts and circumstances that would affect the forfeiture rate.
	Stock Options
	The following table summarizes information with respect to options granted, exercised and canceled in the nine months ended September 27, 2013 and outstanding at September 27, 2013:
			Number of Shares			Weighted Average			Weighted  Average			Aggregate Intrinsic
						Exercise Price			Remaining			Value
									Contractual Term
									(years)
	Outstanding at December 2012			1,514,113		$	6.98			4		$	1,444,653
	Granted
	Exercised			(111,657	)	$	1.15
	Canceled			(38,173	)	$	11.73
	Outstanding at September 27, 2013			1,364,283		$	7.32					$	2,112,313
	Vested and expected to vest at September 27, 2013			1,364,274		$	7.32					$	2,112,310
Vested and exercisable at September 27, 2013			1,363,885		$	7.32					$	2,112,174
There were no options granted by the Company during either of the nine month periods ended September 27, 2013 or September 28, 2012.
The total unamortized expense of the Company’s unvested options, net of forfeitures, as of September 27, 2013, was less than $0.1 million.
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 Restricted Stock Units (“RSU’s”) to certain employees and Restricted Stock Awards (“RSA”) to non-employee directors as part of the Company’s long term equity compensation plan.
Restricted Stock Units — RSU’s are granted to employees with a per share or unit purchase price of zero dollars and either have time based or performance based vesting. RSU’s typically vest over three years, subject to the employee’s continued service with the Company. For purposes of determining compensation expense related to these RSU’s, the fair value is determined based on the closing market price of the Company’s common stock on the date of RSU grant. The expected cost of the grant is reflected over the service period, and is reduced for estimated forfeitures. The Company granted 193,200 RSU’s during the quarter ended March 29, 2013, with a weighted average fair value of $5.39 per share and the Company granted 548,900 RSU’s (including 110,375 performance stock units) during the quarter ended March 30, 2012, with a weighted average fair value of $8.21 per share. The Company granted 408,000 RSU’s (including 152,750 performance stock units) during the quarter ended June 28, 2013 with a weighted average fair value of $6.06 per share and the Company granted 4,450 RSU’s during the quarter ended June 29, 2012 with a weighted average fair value of $6.41 per share. The Company granted 149,950 RSU’s during the quarter ended September 27, 2013, with a weighted average fair value of $6.87 per share and granted 6,000 RSU’s during the quarter ended September 28, 2012 with a weighted average fair value of $6.06 per share. During the nine months ended September 27, 2013 95,457 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 440,647 shares. As of September 27, 2013 approximately $5.6 million of stock-based compensation cost, net of forfeitures, related to RSU’s remains to be recognized, of which substantially all is expected to be recognized over an estimated period of less than three years. As of September 27, 2013 a total of 1,263,633 RSU’s remain outstanding with an aggregate intrinsic value of $8.8 million and a weighted average remaining contractual term of 1.2 years.
Restricted Stock Awards —The total unamortized expense of the Company’s unvested restricted stock awards as of September 27, 2013, was approximately $0.1 million.
The following table summarizes the Company’s restricted stock unit and restricted stock award activity for the nine months ended September 27, 2013:
		Number of
		Shares
Unvested restricted stock units and restricted stock awards at December 28, 2012			1,312,706
Granted			786,150
Vested			(566,104	)
Forfeited			(238,185	)
Unvested restricted stock units and restricted stock awards at September 27, 2013			1,294,567
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 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
Cost of sales(1)		$	159		$	422		$	883		$	1,237
Research and development			69			91			216			256
Sales and marketing			127			118			356			324
General and administrative			771			786			1,990			2,249
Total stock-based compensation expense			1,126			1,417			3,445			4,066
Income tax benefit			(173	)		(341	)		(644	)		(926	)
Total stock-based compensation expense, net of income tax benefit		$	953		$	1,076		$	2,801		$	3,140
	-1	As of September 27, 2013 and September 28, 2012, there were no stock-based compensation expenses capitalized in inventory.

Balance_Sheet_Information

Balance Sheet Information	9 Months Ended
	Sep. 27, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Balance Sheet Information	'
	2. Balance Sheet Information
	Inventory consisted of the following (in thousands):
		September 27,			December 28,
		2013			2012
	Raw materials	$	41,031		$	47,825
	Work in process		14,109			9,994
	Finished goods		2.098			2,349
			57,238			60,168
	Reserve for excess and obsolete		(6,945	)		(6,203	)
	Total	$	50,293		$	53,965
	Equipment and leasehold improvements, net, consisted of the following (in thousands):
		September 27,			December 28,
		2013			2012
	Computer equipment and software	$	9,216		$	8,148
	Furniture and fixtures		2,510			1,682
	Machinery and equipment		15,638			8,597
	Leasehold improvements		13,772			10,092
			41,136			28,519
	Accumulated depreciation		(32,380	)		(19,237	)
	Total	$	8,756		$	9,282

Acquisition

Acquisition	9 Months Ended
	Sep. 27, 2013
Business Combinations [Abstract]	'
Acquisition	'
	3. Acquisition
	On July 3, 2012, the Company completed the acquisition of American Integration Technologies LLC (“AIT”), a supplier of critical subsystems to the semiconductor capital equipment, medical, energy, industrial and aerospace industries, for approximately $75.3 million in cash and 4.5 million shares of newly issued common stock valued at $29.6 million for a total purchase price of $104.9 million. The acquisition serves to increase the Company’s competitive position and market share, as it resulted in an expansion and diversification of the Company’s customer base and product and service portfolio. By acquiring AIT’s complementary product and service portfolio and well established customers, the Company was able to immediately go to market with a more complete and integrated solution. The Company financed the cash portion of the merger, and repaid existing indebtedness, by borrowing a total of $79.8 million under a senior secured credit facility, of which $40.0 million represents borrowings under a term loan and $39.8 million represents borrowings under a revolving credit facility. See further discussion of the borrowing arrangements in Note 5.
	The Company allocated the purchase price of AIT to tangible assets, liabilities and identifiable intangible assets acquired, based on their estimated fair values. Accounts receivable, net of allowance for doubtful accounts and other current assets and liabilities were stated at their historical carrying values, which approximate fair value given the short-term nature of these assets and liabilities. The fair value of the inventory was derived from model-based valuations for which all significant inputs and value drivers are observable directly or indirectly (“Level 2 inputs”). The fair value of fixed assets was determined using market data for similar assets. The fair value of the non-financial assets, summarized below, were derived from significant unobservable inputs (“Level 3 inputs”) determined by management based on market analysis, income analysis and discounted cash flow models. The fair value of purchased identifiable intangible assets was determined using the Company’s discounted cash flow models from income projections prepared by management, using weighted average cost of capital plus a 1.4% premium.
	The excess of purchase price over the aggregate fair values was recorded as goodwill. Although goodwill is not amortized for financial accounting purposes, it is amortized for tax purposes over fifteen years. The Company determined the fair values assigned to identifiable intangible assets acquired based on its consideration of a number of inputs, including an independent third party analysis that was based upon estimates and assumptions provided by the Company. These estimates and assumptions were determined through established and generally accepted valuation techniques. In determining the fair value of the identifiable intangible assets, the Company considered, among other factors, the best use of acquired assets, analyses of historical financial performance and estimates of future performance of AIT’s products. The fair values of identifiable intangible assets were calculated considering market participant expectations and using an income approach. The rates utilized to discount estimated net cash flows to their present values were based on a weighted average cost of capital of 12.5% and a long term growth rate of 4%. This discount rate was determined after consideration of the rate of return on debt capital and equity that typical investors would require from an investment in companies similar in size and operating in similar markets as AIT. The estimated fair value of the tangible and intangible assets acquired was allocated at AIT’s acquisition date. During the quarter ended June 28, 2013, the Company completed the purchase price allocation for the AIT acquisition. The purchase price for the acquisition is allocated as follows (in thousands):
	Fair Market Values
	Cash and cash equivalents	$	380
	Accounts receivable		16,959
	Inventories		23,618
	Other current assets		381
	Property and equipment		1,880
	Goodwill		55,918
	Purchased intangible assets		22,500
	Total assets acquired		121,636
	Accounts payable and accrued expenses		(13,807	)
	Other liabilities		(2,939	)
	Total liabilities assumed		(16,746	)
	Purchase price allocated	$	104,890
	Details of purchased intangible assets with finite lives were as follows as of September 27, 2013 (in thousands):
		Useful		Purchased
		Life		Intangible Assets
		(in years)
	Customer relationships	7		$	19,000
	Trade-name	6			1,900
	Intellectual Property/Know-How	7			1,600
	Total purchased intangible assets				22,500
	Accumulated amortization December 28, 2012				(3,785	)
	Carrying amount December 28, 2012				18,715
	Amortization for the nine months ended September 27, 2013				(4,467	)
	Carrying amount September 27, 2013			$	14,248
	An accelerated method of amortization is used for the Customer Relationships intangible asset based on the expected pattern of future benefits. For the Tradename and Intellectual Property Know-how intangible assets a straight-line amortization method is used.
	The following unaudited pro forma consolidated results of operations assume the acquisition was completed as of the beginning of the fiscal reporting periods presented. The unaudited pro forma consolidated results of operations for the three and nine months ended September 28, 2012 combine the results of Ultra Clean and AIT, as follows:
		Three Months Ended				Nine Months Ended
		September 28, 2012				September 28, 2012
		(In thousands, except per share amounts)
	Net sales	$	100,849			$	380,208
	Net income	$	(177	)		$	9,312
	Basic earnings per share	$	(0.01	)		$	0.33
	Diluted earnings per share	$	(0.01	)		$	0.33
	The unaudited pro forma results above include adjustments related to the purchase price allocation and financing of the acquisition, primarily to increase amortization for the identifiable intangible assets, to increase interest expense for the additional debt incurred to complete the acquisition, to reflect the related income tax effect and to adjust weighted shares issued as part of the acquisition. The pro forma results for the nine months ended September 28, 2012 include acquisition costs of $2.0 million which are not expected to occur in future quarters. The unaudited pro forma condensed combined financial information has been prepared by management for illustrative purposes only and are not necessarily indicative of the consolidated financial position or results of income in future periods or the results that actually would have been realized had Ultra Clean and AIT been a combined company during the specified periods. The unaudited pro forma condensed combined financial information does not reflect any operating efficiencies and/or cost savings that we may achieve with respect to the combined companies, or any liabilities that may result from integration activities.
	Goodwill associated with the acquisition is primarily attributable to the expected synergies and other benefits that the Company believes will result from combining the operations of the Company and AIT. The acquisition serves to increase the Company’s competitive position and market share, as it resulted in an expansion and diversification of the Company’s customer base and product and service portfolio. By acquiring AIT’s complementary product and service portfolio and well established customers, the Company was able to immediately go to market with a more complete and integrated solution.

Goodwill_and_Purchased_Intangi

Goodwill and Purchased Intangible Assets	9 Months Ended
	Sep. 27, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Goodwill and Purchased Intangible Assets	'
	4. 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 process of evaluating the potential impairment of goodwill and intangible assets requires significant judgment. 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.
	During the quarter ended September 27, 2013, the Company concluded there were no triggering events which would require an impairment analysis of the carrying amount of goodwill, primarily due to operating cash flows during the period. During the nine months ended September 27, 2013, the Company reduced the goodwill balance by $0.7 million due to the change in the provisional measurement of acquired inventory and sales and use tax balances. The change was not material to the presented financial statements, therefore the comparative information was not revised.
	Details of goodwill from inception through September 27, 2013 are as follows (in thousands):
			Gross		Accumulated			Net Carrying
			Amount		Impairment			Amount
	Nine Months ended September 27, 2013
	Goodwill (1)		$	89,961	$	(34,043	)	$	55,918
	Year Ended December 28, 2012
	Goodwill (1)		$	90,705	$	(34,043	)	$	56,662
		-1	Represents aggregate goodwill recorded for the UCT acquisition in 2002, the Sieger Engineering LLC acquisition in 2006 and the AIT acquisition in 2012.
	Details of goodwill and other intangible assets were as follows (in thousands):
			September 27, 2013							December 28, 2012
			Goodwill		Intangible			Total		Goodwill			Intangible		Total
					Assets								Assets
	Carrying amount		$	55,918	$	23,235		$	79,153	$	56,662		$	27,702	$	84,364
	Purchased Intangible Assets
	Intangible assets are generally recorded in connection with a business acquisition. The value assigned to the intangible assets purchased as part of the acquisition of AIT was based on estimates and judgments regarding expectations for the success and life cycle of intellectual property/know-how acquired, tradename recognition and developed customer relationships. 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 intangible assets for impairment when events or changes in circumstances indicate their carrying value may not be recoverable. Management considers such indicators as significant differences in actual product acceptance from the estimates, changes in the competitive and economic environment, technological advances, and changes in cost structure.
	Details of purchased intangible assets as of September 27, 2013, are as follows (in thousands):
			As of		As of			As of		Nine Months			As of		Useful Life
			December 28,		December 28,			December 28,		September 27, 2013			September 27,		(in years)
			2012		2012			2012		Amortization			2013
			Purchased		Accumulated			Carrying					Carrying
			Intangible		Amortization			Value					Value
			Assets
	Customer relationships		$	19,000	$	(3,448	)	$	15,552	$	(3,967	)	$	11,585		7
	Tradename (AIT)			1,900		(223	)		1,677		(330	)		1,347		6
	Intellectual property know how			1,600		(114	)		1,486		(170	)		1,316		7
	Tradenames (UCT)			8,987		—			8,987		—			8,987		*
			$	31,487	$	(3,785	)	$	27,702	$	(4,467	)	$	23,235
	*	The UCT tradename was determined to have an indefinite life and is therefore not amortized.
	The Company amortizes its customer relationships intangible asset using an accelerated method over the estimated economic life of the asset, or 7 years. The Company amortizes its trade-name and intellectual property/know-how intangible assets on a straight-line basis ranging from six to seven years. Amortization expense was approximately $1.5 million and $4.5 million for the three and nine months ended September 27, 2013, respectively. Amortization expense was $1.9 million for the three and nine months ended September 28, 2012.
	As of September 27, 2013, future estimated amortization expense is expected to be as follows (in thousands):
			Amortization
			Expense
	2013 (remaining in year)		$	1,526
	2014			4,884
	2015			2,813
	2016			2,293
	2017			1,387
	2018			848
	2019			497
	Total		$	14,248
	In addition to the AIT tradename intangible of $1.9 million, which the Company concluded has a definite life of six years, the Company is also carrying a UCT tradename intangible asset of $9.0 million as a result of a previous acquisition. The Company concluded that the UCT trade-name intangible asset life is indefinite and is therefore not amortized. During the quarter ended September 27, 2013, the Company concluded there were no triggering events which would require an impairment analysis of the carrying amount of UCT tradename, primarily due to operating cash flows during the period.

Borrowing_Arrangements

Borrowing Arrangements	9 Months Ended
	Sep. 27, 2013
Debt Disclosure [Abstract]	'
Borrowing Arrangements	'
	5. Borrowing Arrangements
	On July 3, 2012, in connection with the Company’s acquisition of AIT and the refinancing of its prior credit facility, the Company entered into a credit agreement (the “Credit Agreement”) by and among the Company, certain of its subsidiaries, Silicon Valley Bank, U.S. Bank National Association and HSBC Bank (collectively, the “Lenders”). The Credit Agreement provides for a term loan in an aggregate principal amount of $40.0 million (the “Term Loan”) and a revolving credit facility in an aggregate principal amount of $40.0 million (the “Revolving Credit Facility”), a letter of credit facility in the aggregate availability amount of $15.0 million (as a sublimit of such Revolving Credit Facility) (the “L/C Facility”) and a swing line sub-facility in the aggregate availability amount of $4.0 million (as a sublimit of the Revolving Credit Facility) (together with the Term Loan, the Revolving Credit Facility and the L/C Facility, the “Credit Facility”). On July 3, 2012, the Company borrowed an aggregate of $40.0 million under the Term Loan and approximately $39.8 million under the Revolving Credit Facility. The borrowed funds were used at the closing of the Company’s acquisition of AIT to finance the acquisition and repay the outstanding balance of $3.7 million to Silicon Valley Bank as lender under the Company’s prior credit facility. The prior credit facility was terminated in connection with this transaction.
	The Credit Facility must be repaid in consecutive quarterly installments of $2.5 million, with the first payment made on September 30, 2012, and with the balance of the then-outstanding principal amount due at the final maturity, which is July 3, 2016. The Revolving Credit Facility is available for the four-year period beginning on July 3, 2012. The Credit Agreement includes customary representations, warranties, covenants and events of default. The Company and certain of its subsidiaries have agreed to secure all of their obligations under the Credit Agreement by granting a first priority lien in substantially all of their respective personal property assets of these entities (subject to certain exceptions and limitations).
	At the Company’s option, borrowings under the Term Loan and Revolving Credit Facility (subject to certain limitations) bear interest at either a base rate or at the London Interbank Offered Rate (“LIBOR”) (with the LIBOR being adjusted for certain Eurocurrency reserve requirements, if any, as described in the Credit Agreement), plus, in each case, an applicable margin based on the Company’s consolidated leverage ratio. All loans described above made on July 3, 2012 were initially base rate loans, carrying interest of 3.75%. The Company expects, however, that the effective interest rate will be higher due to the incurrence of certain loan-related costs of approximately $1.9 million that will be treated as deferred interest and amortized over the life of the loan.
	The Credit Agreement requires the Company to maintain certain financial covenants including a minimum consolidated fixed charge coverage ratio, a maximum consolidated leverage ratio and minimum domestic cash balances. On February 15, 2013, the Company and the Lenders amended the Credit Agreement in order to modify the financial covenants contained in the Credit Agreement, effective January 30, 2013. The Credit Agreement, as amended, requires the Company to comply with the following financial covenants:
		•	a minimum consolidated fixed charge coverage ratio (as defined in the Credit Agreement, as amended), measured over the preceding four fiscal quarters, beginning as of the end of the third quarter of fiscal 2014, of 1.10 to 1.00, stepping up to 1.25 to 1.00 as of the end of each fiscal quarter beginning with the first quarter of fiscal 2015 and thereafter;
		•	a maximum consolidated leverage ratio (as defined in the Credit Agreement, as amended) measured over the preceding four fiscal quarters, beginning, as of the end of the third quarter of fiscal 2014, of 4.00 to 1.00, stepping down to 3.75 to 1.00 as of the end of the fourth quarter of fiscal 2014 and thereafter to and including the third quarter of 2015, and 3.25 to 1.00 as of the end of each fiscal quarter beginning with the fourth quarter of 2015 and thereafter;
		•	minimum domestic cash of $15.0 million as of the last day of any fiscal quarter and $10.0 million as of the last day of any other fiscal month from January 25, 2013 and thereafter;
		•	a minimum consolidated quick ratio (as defined in the Credit Agreement, as amended) of 1.10 to 1.00 as of the end of each fiscal month from January 25, 2013 and thereafter;
		•	minimum consolidated adjusted EBITDA (as defined in the Credit Agreement, as amended), measured over the preceding two quarters, of $3.5 million as of the end of the fourth quarter of 2012, $2.5 million as of the end of the first quarter of 2013, $3.0 million as of the end of the second quarter of 2013, $4.0 million as of the end of the third quarter of 2013, $6.0 million as of the end of the fourth quarter of 2013, $7.0 million as of the end of the first quarter of 2014 and $8.0 million as of the end of the second quarter of 2014 and each quarter thereafter.
	For the quarter ended September 27, 2013, the Company was in compliance with all covenants.
	The Credit Agreement contains provisions requiring the following mandatory prepayments (subject to certain exceptions and limitations): (i) prepayments equal to 50% of the net cash proceeds from the issuance of capital stock by the Company’s primary operating subsidiary (or any of its subsidiaries); (ii) prepayments equal to 100% of the net cash proceeds from the incurrence of any indebtedness by the Company’s primary operating subsidiary over $250,000; (iii) prepayments equal to the net cash proceeds from certain asset sales or insurance or condemnation recoveries; and (iv) annual prepayments in an amount equal to (a) 33% of excess cash flow (as defined in the Credit Agreement, as amended) 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.
	As of September 27, 2013, the outstanding amounts under the Company’s Term Loan and Revolving Credit Facility were $30.0 million and $26.5 million, respectively, which are net of unamortized debt issuance costs of $1.3 million for a total debt balance of $56.5 million. The Company analyzed the Credit Agreement and determined that the outstanding balance of Revolving Credit Facility debt should be classified as short-term due to acceleration clauses in the agreement.

Income_Tax

Income Tax	9 Months Ended
	Sep. 27, 2013
Income Tax Disclosure [Abstract]	'
Income Tax	'
	6. Income Tax
	The Company’s income tax provision and related effective tax rate for the three and nine month periods ended September 27, 2013 was $375,000 and 15.5% and $931,000 and 18.7%, respectively, compared to $(356,000) and 24.1% and $2,804,000 and 30.7%, respectively for the same periods a year ago. The change in respective rates reflects, primarily, changes in the geographic mix of worldwide earnings to foreign jurisdictions with lower tax rates or tax holidays offset by certain discrete tax items during 2013.
	Undistributed earnings of the Company’s foreign subsidiaries at September 27, 2013, are considered to be indefinitely reinvested and no provision for U.S. income taxes has been provided thereon. Upon distribution of those earnings in the form of dividends or otherwise, the Company would be subject to U.S. income taxes. It is not practicable to determine the income tax liability that might be incurred if these earnings were to be distributed.
	The following table summarizes the activity related to the Company’s uncertain tax positions (in thousands):
		Nine months ended
		September 27,			September 28,
		2013			2012
	Balance as of the beginning of period	$	109		$	132
	Finalization of tax audits		—			(21	)
	Decreases related to prior year tax positions		(22	)		—
	Balance as of the end of period	$	87		$	111
	The Company’s gross liability for unrecognized tax benefits as of September 27, 2013 and September 28, 2012, was $87,000 and $111,000, respectively. Increases or decreases to interest and penalties on uncertain tax positions are included in income tax provision (benefit) in the Condensed Consolidated Statements of Operations. Interest related to uncertain tax positions was $3,000 for each of the nine months ended September 27, 2013 and September 28, 2012, 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.
	The determination of the Company’s tax provision is subject to judgments and estimates. The carrying value of the Company’s net deferred tax assets, which is made up primarily of tax deductions, assumes the Company will be able to generate sufficient future income to fully realize these deductions. In determining whether the realization of these deferred tax assets may be impaired, the Company makes judgments with respect to whether the Company is likely to generate sufficient future taxable income to realize these assets. In addition, the calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. Resolution of these uncertainties in a manner inconsistent with the Company’s expectations could have a material impact on the Company’ results of operations and financial position.
	As of September 27, 2013, the Company maintained a full valuation allowance on the deferred tax assets of one of its China subsidiaries in the amount of $851,000 as the Company believes it is more likely than not that the deferred tax asset will not be realized. In order to reverse a valuation allowance, (GAAP) suggests that the Company review the cumulative income/loss in recent years as well as determine the Company’s ability to generate sufficient future taxable income to realize the Company’s net deferred tax assets.
	The Company files income tax returns in the U.S. federal jurisdiction, various states and foreign jurisdictions. The Company’s 2010 through 2012 federal income tax returns are open to audit through the statute of limitations by the Internal Revenue Service. The Company’s 2008 through 2012 state income tax returns are open to audit by the California Franchise Tax Board. The Company is also subject to examination in various other jurisdictions for various periods. The Company is currently experiencing a tax holiday related to its Singapore subsidiary that will expire for tax years beginning January 2015. The Company’s Singapore subsidiary recorded a net profit, considered insignificant by the Company, for the quarter ended September 27, 2013.

Net_Income_Per_Share

Net Income Per Share	9 Months Ended
	Sep. 27, 2013
Earnings Per Share [Abstract]	'
Net Income Per Share	'
	7. 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 27,		September 28,			September 27,		September 28,
		2013		2012			2013		2012
	Net income	$	2,048	$	(1,123	)	$	4,053	$	6,327
	Denominator:
	Shares used in computation — basic:
	Weighted average common shares outstanding		28,451		27,656			28,265		24,851
	Shares used in computation — diluted:
	Shares used in computing basic net income per share		28,451		27,656			28,265		24,851
	Dilutive effect of common shares outstanding subject to repurchase		241					365		265
	Dilutive effect of options outstanding		287					249		377
	Weighted average shares used in computing diluted net income per share		28,979		27,656			28,879		25,493
	Net income per share — basic	$	0.07	$	(0.04	)	$	0.14	$	0.25
	Net income per share — diluted	$	0.07	$	(0.04	)	$	0.14	$	0.25
	The Company had securities outstanding which could potentially dilute basic earnings 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 (loss) per share, as their effect would have been anti-dilutive. Such outstanding securities consisted of 575,470 and 1,013,361 stock options outstanding for the three month ended September 27, 2013 and September 28, 2012 as well as 996,495 and 612,069 stock options for the nine months ended September 27, 2013 and September 28, 2012, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 27, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	8. Commitments and Contingencies
	The Company had commitments to purchase inventory totaling approximately $52.5 million at September 27, 2013.
	The Company leases properties domestically in Hayward, California; Austin, Texas; Pflugerville, Texas; Chandler, Arizona, and South San Francisco, California and internationally in China, Singapore and the Philippines. The Company leases certain of its facilities under non-cancelable leases, which expire on various dates through 2022.
	As of September 27, 2013, future minimum payments under these operating leases were as follows (in thousands):
	Fiscal year
	2013 (remaining in year)	$	1,330
	2014		5,108
	2015		4,577
	2016		3,952
	2017		3,347
	Thereafter		9,485
	Total minimum lease payments	$	27,799
	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, results of operations or cash flows.

Segment_Information

Segment Information	9 Months Ended
	Sep. 27, 2013
Segment Reporting [Abstract]	'
Segment Information	'
	9. Segment Information
	The Company operates in one reportable segment and is engaged in the development, manufacture and supply of critical subsystems and systems for the semiconductor capital equipment, flat panel, medical, energy and research industries. Multiple operating segments were aggregated into one 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 the Company’s products. In addition, all operating segments have similar economic characteristics. The Company’s foreign operations are conducted primarily through its wholly-owned subsidiary in China. The Company’s principal markets include North America, Asia and, to a lesser degree, Europe. Sales by geographic area represent sales to unaffiliated customers.
	All information on sales by geographic area is 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
		Sept 27,		Sept 28,		Sept 27,		Sept 28,
		2013		2012		2013		2012
	United States	$	76,388	$	84,437	$	244,476	$	239,716
	China		10,521		6,033		24,954		20,939
	Singapore		17,602		9,908		40,094		50,145
	Other		2,672		471		8,230		2,563
		$	107,183	$	100,849	$	317,754	$	313,363
	At September 27, 2013 and September 28, 2012, approximately $4.5 million and $4.2 million, respectively, of the Company’s net long-lived assets were located in Asia, and the remaining balances were located in the United States.

Correction_of_Previously_Repor

Correction of Previously Reported Quarterly Financial Statements	9 Months Ended
	Sep. 27, 2013
Accounting Changes And Error Corrections [Abstract]	'
Correction of Previously Reported Quarterly Financial Statements	'
	10. Correction of Previously Reported Quarterly Financial Statements
	As described in the Annual Report on Form 10-K for the year ended December 28, 2012, the Company has made certain corrections to amounts previously reported for the three and nine month periods ended September 28, 2012. The Company has concluded that, due to the nature of the affected expenses, these corrections were not material to the interim financial statements for the three and nine month periods ended September 28, 2012. The Company has included such corrections to its 2012 interim financial statements for the periods ended September 28, 2012 within this report on Form 10-Q.
			Three Months			Corrections to			Three months			Nine months		Corrections to			Nine months
			ended			the  three			ended			ended		the  nine			ended
			September 28,			months ended			September 28,			September 28,		months ended			September 28,
			2012 as			September 28, 2012			2012 as			2012 as		September 28, 2012			2012 as
			reported						corrected			reported					corrected
			(In thousands, except per share data)
	Sales		$	100,849					$	100,849		$	313,363				$	313,363
	Gross profit		$	14,323					$	14,323		$	44,237				$	44,237
	Operating expenses		$	15,750		$	(761	)(a)(b)	$	14,989		$	34,481	$	(307	)(b)	$	34,174
	Income from operations		$	(1,427	)	$	761		$	(666	)	$	9,756	$	307		$	10,063
	Income tax provision		$	(539	)	$	183	(c)	$	(356	)	$	1,942	$	862	(c)(d)	$	2,804
	Net income (loss)		$	(1,701	)	$	578		$	(1,123	)	$	6,882	$	(555	)	$	6,327
	Earnings per share — basic		$	(0.06	)	$	0.02		$	(0.04	)	$	0.28	$	(0.03	)	$	0.25
	Earnings per share — diluted		$	(0.06	)	$	0.02		$	(0.04	)	$	0.27	$	(0.02	)	$	0.25
	The corrections relate to:
	a)	$454,000 of costs associated with the acquisition of AIT that were capitalized at June 29, 2012 and expensed in the quarter ended September 28, 2012, which should have been expensed in the quarter ended June 29, 2012;
	b)	$307,000 of performance equity award expenses originally reversed in the quarter ended December 28, 2012, that should have been reversed in the quarter ended September 28, 2012;
	c)	the tax effect of items a) and b) above; and,
	d)	foreign tax payments of $770,000 that were recorded as a reduction of other current liabilities as of September 28, 2012 and expensed in the quarter ended December 28, 2012 but should have been expensed in the quarter ended June 29, 2012.

Organization_and_Significant_A1

Organization and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 27, 2013
Accounting Policies [Abstract]	'
Organization	'
	Organization — Ultra Clean Holdings, Inc. (the “Company”) is a leading developer and supplier of critical subsystems, primarily for the semiconductor capital equipment industry. The Company also leverages the specialized skill sets required to support semiconductor capital equipment to serve the technologically similar markets in the flat panel, medical, energy and research industries, collectively referred to as “Other Addressed Industries”. The Company develops, designs, prototypes, engineers, manufactures and tests subsystems which are highly specialized and tailored to specific steps in the semiconductor manufacturing process as well as the manufacturing processes in Other Addressed Industries. Revenue is derived from the sale of gas delivery systems and other critical subsystems including chemical mechanical planarization (CMP) subsystems, chemical delivery modules, top-plate assemblies, frame assemblies, process modules and other high level assemblies.
	The Company’s customers are primarily original equipment manufacturers (OEMs) in industries it supports, providing customers complete subsystem solutions that combine the Company’s expertise in design, test, component characterization and highly flexible manufacturing operations with quality control and financial stability. This combination helps the Company to drive down total manufacturing costs, reduce design-to-delivery cycle times and maintain high quality standards for the Company’s customers. The Company believes these characteristics, as well as the Company’s standing as a leading supplier of gas delivery systems and other critical subsystems, place the Company in a strong position to benefit from the demand for subsystem outsourcing.
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 subsidiaries and have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). This financial information reflects all adjustments which are, in the opinion of the Company, normal, recurring and necessary to present fairly the statements of financial position, results of operations and cash flows 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 28, 2012, balance sheet data was derived from audited financial statements as of that date.
	In July 2012, the Company completed its acquisition of American Integration Technologies LLC (“AIT”). Beginning in the third quarter of fiscal 2012, the acquired business is included in the Company’s consolidated results of operations.
Principles of Consolidation	'Principles of Consolidation — The Company’s condensed consolidated financial statements include the accounts of the Company and its subsidiaries and all intercompany accounts and transactions have been eliminated in consolidation
Foreign Currency Translation	'
	Foreign Currency Translation — The Company has reviewed its non-U.S. subsidiaries (of which all of its non-U.S. asset base resides in Asia) that operate in a local currency environment to determine their functional currency by examining how and in what currency each subsidiary generates cash through billings and cash receipts and how and in what currency the subsidiary expends cash through payment of its vendors and payment of its workforce. Also, these subsidiaries’ individual assets and liabilities that are primarily denominated in the local foreign currency are examined for their impact on the Company’s cash flows. All have been determined to have the U.S. dollar as its functional currency. Foreign currency transaction gains and losses are recorded in other income (expense), net.
Use of Accounting Estimates	'
	Use of Accounting Estimates — The presentation of condensed financial statements in conformity with Generally Accepted Accounting Principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. 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.
Certain Significant Risks and Uncertainties	'
	Certain Significant Risks and Uncertainties — The Company operates in a dynamic industry and, accordingly, can be affected by a variety of factors. For example, any of the following areas could have a negative effect on the Company in terms of its future financial position, results of operations or cash flows: the general state of the U.S. and world economies, the highly cyclical nature of the industries the Company serves; the loss of any of a small number of customers; ability to obtain additional financing; inability to meet certain debt covenants; failure to successfully integrate completed acquisitions; ineffectiveness in pursuing acquisition opportunities; regulatory changes; fundamental changes in the technology underlying semiconductor, flat panel, solar and medical device manufacturing processes or manufacturing equipment; the hiring, training and retention of key employees; successful and timely completion of product design efforts; and new product design introductions by competitors.
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 had significant sales to three customers, each of which accounted for 10% or more of sales for the three months ended September 27, 2013 and September 28, 2012. The Company had significant sales to three customers, each of which accounted for 10% or more of sales for the nine months ended September 27, 2013 and two of which counted for 10% or more of sales for the nine months ended September 28, 2012. Sales to each of these customers as a percentage of total sales were as follows:
			Three months ended						Nine months ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Applied Materials, Inc.			32.9	%		29.4	%		33.1	%		39.6	%
	Lam Research Corporation (1)			37.4	%		27.5	%		33.2	%		34.4	%
	ASM International (2)			10.8	%		19.5	%		13.4	%		—
	Total			81.1	%		76.4	%		79.7	%		74	%
	-1	In June 2012, Lam Research Corporation completed the acquisition of Novellus Systems, Inc., one of the Company’s customers. The sales percentages for Lam Research Corporation for the nine months ended September 28, 2012, reflect the inclusion of sales to Novellus Systems, Inc., from the beginning of fiscal 2012 for comparison purposes.
	-2	Sales to ASM International are the result of the Company’s acquisition of AIT during the third quarter of 2012.
	Three customers’ accounts receivable balances: Applied Materials, Inc., Lam Research Corporation and ASM International were individually greater than 10% of accounts receivable as of September 27, 2013 and as of December 28, 2012, and, in the aggregate, represented approximately 79% and 84%, respectively, of accounts receivable.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments-The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable and bank borrowings. The carrying value of cash and cash equivalents, accounts receivable and accounts payable approximates their fair value because of their short-term nature.
	The accounting guidance for fair value measurements prioritizes the inputs used in measuring fair value in the following hierarchy:
	Level I — Quoted prices in active markets for identical assets or liabilities,
	Level 2 — Observable inputs other than the Level I prices for similar assets or liabilities; quoted prices in active markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities,
	Level 3 — Unobservable inputs in which there is little or no market data, and that are significant to the fair value of the assets or liabilities.
	The Company’s only financial asset measured at fair value on a recurring basis is an overnight sweep account invested in money market funds which are presented as cash and cash equivalents with a carrying value and fair value of $17.9 million at September 27, 2013, based on Level 2 inputs. The Company’s only financial liability measured at fair value is the amount outstanding under our credit facility. Specifically, the fair value of outstanding borrowings under our term loan was based on level 2 inputs and fair value was determined using quoted prices for similar liabilities in inactive markets and our outstanding borrowings under our revolving credit facility were 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 our long term loan and revolving credit facility.
Fiscal Year	'
	Fiscal Year — 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.
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. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.
	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 consolidated statements of income as income tax expense.
	The determination of the Company’s tax provision is subject to judgments and estimates. The carrying value of the Company’s net deferred tax assets, which is made up primarily of tax deductions, assumes the Company will be able to generate sufficient future income to fully realize these deductions. In determining whether the realization of these deferred tax assets may be impaired, the Company makes judgments with respect to whether it is likely to generate sufficient future taxable income to realize these assets. The Company has a valuation allowance on the deferred tax assets of one of its China subsidiaries in the amount of $851,000 as of September 27, 2013 and December 28, 2012.
	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 tax audits, however, the outcome of tax audits cannot be predicted with certainty.
Product Warranty	'
	Product Warranty — The Company provides a warranty on its products for a period of up to two years and reserves for expected warranty liabilities at the time of sale based on historical activity. The determination of such reserves 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 cost of sales may be required in future periods. Components in the reserve for warranty costs consisted of the following for the periods set forth below (in thousands):
			Nine months ended
			September 27,			September 28,
			2013			2012
	Beginning balance		$	152		$	350
	Change in reserve			70			(4	)
	Warranty claims			(119	)		(112	)
	Ending balance		$	103		$	234
Revenue Recognition	'
	Revenue Recognition — Product revenue is generally recorded upon shipment. In arrangements which specify title transfer upon delivery, revenue is not recognized until the product is delivered. The Company recognizes revenue when persuasive evidence of an arrangement exists, shipment or delivery, as applicable, 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 (loss) per Share	'
	Net Income (loss) per Share — Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of shares outstanding for the period. Diluted net income (loss) per share is calculated by dividing net income (loss) 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 7 to Condensed Consolidated Financial Statements).
Comprehensive Income (Loss)	'
	Comprehensive Income (Loss) — The Company reports by major components and as a single total, the change in its net assets during the period from non-owner sources. Comprehensive income (loss) for all periods presented was the same as net income (loss).
Segments	'
	Segments — The Financial Accounting Standards Board’s (FASB) guidance regarding disclosure about segments in an enterprise and related information establishes standards for the reporting by public business enterprises of information about reportable segments, products and services, geographic areas, and major customers. The method for determining what information to report is based on the manner in which management organizes the reportable segments within the Company for making operational decisions and assessments of financial performance. The Company’s chief operating decision-maker is considered to be the Chief Executive Officer. The Company operates in one reporting segment.
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, for 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 of the Company. These equity-based awards include stock options, restricted stock awards and restricted stock units which can be either time-based or performance-based. 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 over the awards’ vesting period on a straight-line basis over a weighted average period of four years for stock options (three years for restricted stock units and one year for restricted stock awards) and will be adjusted for subsequent changes in estimated forfeitures and future option grants.
	The Company applies the fair value recognition provisions based on the FASB’s guidance regarding stock-based compensation. The exercise price of each stock option equals the market price of the Company’s stock on the date of grant. The estimated fair value of the Company’s equity-based awards, less expected forfeitures, is amortized over the awards’ vesting periods on a straight-line basis over the applicable vesting period and will be adjusted for subsequent changes in estimated forfeitures and future option grants. Most options are scheduled to vest over four years and expire no later than ten years from the grant date. The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model. The determination of the fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price as well as assumptions regarding a number of complex and subjective variables. These variables include the expected term of the awards; the Company’s expected stock price volatility over the term of the awards, actual and projected employee stock option exercise behaviors, risk-free interest rate and expected dividends. The Company estimates the expected term of share-based awards granted based on the Company’s historical option term experience. The Company estimates the volatility of its common stock based upon the Company’s historical stock price volatility over the length of the expected term of the options. The Company bases the risk-free interest rate that it uses in the option valuation model on U.S. Treasury zero-coupon bond issues with remaining maturities similar to the expected term of the options. The Company does not anticipate paying any cash dividends in the foreseeable future and therefore uses an expected dividend yield of zero in the option valuation model. The Company is required to estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and records share-based compensation expense only for those awards that are expected to vest. The Company also considers, each quarter, whether there have been any significant changes in facts and circumstances that would affect the forfeiture rate.
Stock Options	'
	Stock Options
	The following table summarizes information with respect to options granted, exercised and canceled in the nine months ended September 27, 2013 and outstanding at September 27, 2013:
			Number of Shares			Weighted Average			Weighted  Average			Aggregate Intrinsic
						Exercise Price			Remaining			Value
									Contractual Term
									(years)
	Outstanding at December 2012			1,514,113		$	6.98			4		$	1,444,653
	Granted
	Exercised			(111,657	)	$	1.15
	Canceled			(38,173	)	$	11.73
	Outstanding at September 27, 2013			1,364,283		$	7.32					$	2,112,313
	Vested and expected to vest at September 27, 2013			1,364,274		$	7.32					$	2,112,310
	Vested and exercisable at September 27, 2013			1,363,885		$	7.32					$	2,112,174
	There were no options granted by the Company during either of the nine month periods ended September 27, 2013 or September 28, 2012.
	The total unamortized expense of the Company’s unvested options, net of forfeitures, as of September 27, 2013, was less than $0.1 million.
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 Restricted Stock Units (“RSU’s”) to certain employees and Restricted Stock Awards (“RSA”) to non-employee directors as part of the Company’s long term equity compensation plan.
	Restricted Stock Units — RSU’s are granted to employees with a per share or unit purchase price of zero dollars and either have time based or performance based vesting. RSU’s typically vest over three years, subject to the employee’s continued service with the Company. For purposes of determining compensation expense related to these RSU’s, the fair value is determined based on the closing market price of the Company’s common stock on the date of RSU grant. The expected cost of the grant is reflected over the service period, and is reduced for estimated forfeitures. The Company granted 193,200 RSU’s during the quarter ended March 29, 2013, with a weighted average fair value of $5.39 per share and the Company granted 548,900 RSU’s (including 110,375 performance stock units) during the quarter ended March 30, 2012, with a weighted average fair value of $8.21 per share. The Company granted 408,000 RSU’s (including 152,750 performance stock units) during the quarter ended June 28, 2013 with a weighted average fair value of $6.06 per share and the Company granted 4,450 RSU’s during the quarter ended June 29, 2012 with a weighted average fair value of $6.41 per share. The Company granted 149,950 RSU’s during the quarter ended September 27, 2013, with a weighted average fair value of $6.87 per share and granted 6,000 RSU’s during the quarter ended September 28, 2012 with a weighted average fair value of $6.06 per share. During the nine months ended September 27, 2013 95,457 vested shares were withheld to satisfy withholding tax obligations, resulting in the net issuance of 440,647 shares. As of September 27, 2013 approximately $5.6 million of stock-based compensation cost, net of forfeitures, related to RSU’s remains to be recognized, of which substantially all is expected to be recognized over an estimated period of less than three years. As of September 27, 2013 a total of 1,263,633 RSU’s remain outstanding with an aggregate intrinsic value of $8.8 million and a weighted average remaining contractual term of 1.2 years.
	Restricted Stock Awards —The total unamortized expense of the Company’s unvested restricted stock awards as of September 27, 2013, was approximately $0.1 million.
	The following table summarizes the Company’s restricted stock unit and restricted stock award activity for the nine months ended September 27, 2013:
			Number of
			Shares
	Unvested restricted stock units and restricted stock awards at December 28, 2012			1,312,706
	Granted			786,150
	Vested			(566,104	)
	Forfeited			(238,185	)
	Unvested restricted stock units and restricted stock awards at September 27, 2013			1,294,567
	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 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Cost of sales(1)		$	159		$	422		$	883		$	1,237
	Research and development			69			91			216			256
	Sales and marketing			127			118			356			324
	General and administrative			771			786			1,990			2,249
	Total stock-based compensation expense			1,126			1,417			3,445			4,066
	Income tax benefit			(173	)		(341	)		(644	)		(926	)
	Total stock-based compensation expense, net of income tax benefit		$	953		$	1,076		$	2,801		$	3,140
		-1	As of September 27, 2013 and September 28, 2012, there were no stock-based compensation expenses capitalized in inventory.

Organization_and_Significant_A2

Organization and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 27, 2013
Accounting Policies [Abstract]	'
Customers as Percentage of Total Sales	'
	Sales to each of these customers as a percentage of total sales were as follows:
			Three months ended						Nine months ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Applied Materials, Inc.			32.9	%		29.4	%		33.1	%		39.6	%
	Lam Research Corporation (1)			37.4	%		27.5	%		33.2	%		34.4	%
	ASM International (2)			10.8	%		19.5	%		13.4	%		—
	Total			81.1	%		76.4	%		79.7	%		74	%
	-1	In June 2012, Lam Research Corporation completed the acquisition of Novellus Systems, Inc., one of the Company’s customers. The sales percentages for Lam Research Corporation for the nine months ended September 28, 2012, reflect the inclusion of sales to Novellus Systems, Inc., from the beginning of fiscal 2012 for comparison purposes.
	-2	Sales to ASM International are the result of the Company’s acquisition of AIT during the third quarter of 2012.
Components in Reserve for Warranty Costs	'
	Components in the reserve for warranty costs consisted of the following for the periods set forth below (in thousands):
			Nine months ended
			September 27,			September 28,
			2013			2012
	Beginning balance		$	152		$	350
	Change in reserve			70			(4	)
	Warranty claims			(119	)		(112	)
	Ending balance		$	103		$	234
Summary of Information with Respect to Options Granted, Exercised and Canceled	'
	The following table summarizes information with respect to options granted, exercised and canceled in the nine months ended September 27, 2013 and outstanding at September 27, 2013:
			Number of Shares			Weighted Average			Weighted Average			Aggregate Intrinsic
						Exercise Price			Remaining			Value
									Contractual Term
									(years)
	Outstanding at December 2012			1,514,113		$	6.98			4		$	1,444,653
	Granted
	Exercised			(111,657	)	$	1.15
	Canceled			(38,173	)	$	11.73
	Outstanding at September 27, 2013			1,364,283		$	7.32					$	2,112,313
	Vested and expected to vest at September 27, 2013			1,364,274		$	7.32					$	2,112,310
	Vested and exercisable at September 27, 2013			1,363,885		$	7.32					$	2,112,174
Restricted Stock Unit and Restricted Stock Award Activity	'
	The following table summarizes the Company’s restricted stock unit and restricted stock award activity for the nine months ended September 27, 2013:
			Number of
			Shares
	Unvested restricted stock units and restricted stock awards at December 28, 2012			1,312,706
	Granted			786,150
	Vested			(566,104	)
	Forfeited			(238,185	)
	Unvested restricted stock units and restricted stock awards at September 27, 2013			1,294,567
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 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Cost of sales(1)		$	159		$	422		$	883		$	1,237
	Research and development			69			91			216			256
	Sales and marketing			127			118			356			324
	General and administrative			771			786			1,990			2,249
	Total stock-based compensation expense			1,126			1,417			3,445			4,066
	Income tax benefit			(173	)		(341	)		(644	)		(926	)
	Total stock-based compensation expense, net of income tax benefit		$	953		$	1,076		$	2,801		$	3,140
		-1	As of September 27, 2013 and September 28, 2012, there were no stock-based compensation expenses capitalized in inventory.

Balance_Sheet_Information_Tabl

Balance Sheet Information (Tables)	9 Months Ended
	Sep. 27, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Summary of Inventory	'
	Inventory consisted of the following (in thousands):
		September 27,			December 28,
		2013			2012
	Raw materials	$	41,031		$	47,825
	Work in process		14,109			9,994
	Finished goods		2.098			2,349
			57,238			60,168
	Reserve for excess and obsolete		(6,945	)		(6,203	)
	Total	$	50,293		$	53,965
Equipment and Leasehold Improvements, Net	'
	Equipment and leasehold improvements, net, consisted of the following (in thousands):
		September 27,			December 28,
		2013			2012
	Computer equipment and software	$	9,216		$	8,148
	Furniture and fixtures		2,510			1,682
	Machinery and equipment		15,638			8,597
	Leasehold improvements		13,772			10,092
			41,136			28,519
	Accumulated depreciation		(32,380	)		(19,237	)
	Total	$	8,756		$	9,282

Acquisition_Tables

Acquisition (Tables)	9 Months Ended
	Sep. 27, 2013
Business Combinations [Abstract]	'
Purchase Price for Acquisitions	'
	The purchase price for the acquisition is allocated as follows (in thousands):
	Fair Market Values
	Cash and cash equivalents	$	380
	Accounts receivable		16,959
	Inventories		23,618
	Other current assets		381
	Property and equipment		1,880
	Goodwill		55,918
	Purchased intangible assets		22,500
	Total assets acquired		121,636
	Accounts payable and accrued expenses		(13,807	)
	Other liabilities		(2,939	)
	Total liabilities assumed		(16,746	)
	Purchase price allocated	$	104,890
Details of Finite-Lived Intangible Assets	'
	Details of purchased intangible assets with finite lives were as follows as of September 27, 2013 (in thousands):
		Useful		Purchased
		Life		Intangible Assets
		(in years)
	Customer relationships	7		$	19,000
	Trade-name	6			1,900
	Intellectual Property/Know-How	7			1,600
	Total purchased intangible assets				22,500
	Accumulated amortization December 28, 2012				(3,785	)
	Carrying amount December 28, 2012				18,715
	Amortization for the nine months ended September 27, 2013				(4,467	)
	Carrying amount September 27, 2013			$	14,248
Unaudited Proforma Consolidated Results of Operations	'
	The unaudited pro forma consolidated results of operations for the three and nine months ended September 28, 2012 combine the results of Ultra Clean and AIT, as follows:
		Three Months Ended				Nine Months Ended
		September 28, 2012				September 28, 2012
		(In thousands, except per share amounts)
	Net sales	$	100,849			$	380,208
	Net income	$	(177	)		$	9,312
	Basic earnings per share	$	(0.01	)		$	0.33
	Diluted earnings per share	$	(0.01	)		$	0.33

Goodwill_and_Purchased_Intangi1

Goodwill and Purchased Intangible Assets (Tables)	9 Months Ended
	Sep. 27, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Details of Goodwill	'
	Details of goodwill from inception through September 27, 2013 are as follows (in thousands):
			Gross		Accumulated			Net Carrying
			Amount		Impairment			Amount
	Nine Months ended September 27, 2013
	Goodwill (1)		$	89,961	$	(34,043	)	$	55,918
	Year Ended December 28, 2012
	Goodwill (1)		$	90,705	$	(34,043	)	$	56,662
		-1	Represents aggregate goodwill recorded for the UCT acquisition in 2002, the Sieger Engineering LLC acquisition in 2006 and the AIT acquisition in 2012.
Goodwill and Other Indefinite Lived Intangible Assets	'
	Details of goodwill and other intangible assets were as follows (in thousands):
			September 27, 2013							December 28, 2012
			Goodwill		Intangible			Total		Goodwill			Intangible		Total
					Assets								Assets
	Carrying amount		$	55,918	$	23,235		$	79,153	$	56,662		$	27,702	$	84,364
Summary of Purchased Intangible Assets	'
	Details of purchased intangible assets as of September 27, 2013, are as follows (in thousands):
			As of		As of			As of		Nine Months			As of		Useful Life
			December 28,		December 28,			December 28,		September 27, 2013			September 27,		(in years)
			2012		2012			2012		Amortization			2013
			Purchased		Accumulated			Carrying					Carrying
			Intangible		Amortization			Value					Value
			Assets
	Customer relationships		$	19,000	$	(3,448	)	$	15,552	$	(3,967	)	$	11,585		7
	Tradename (AIT)			1,900		(223	)		1,677		(330	)		1,347		6
	Intellectual property know how			1,600		(114	)		1,486		(170	)		1,316		7
	Tradenames (UCT)			8,987		—			8,987		—			8,987		*
			$	31,487	$	(3,785	)	$	27,702	$	(4,467	)	$	23,235
	*	The UCT tradename was determined to have an indefinite life and is therefore not amortized.
Future Estimated Amortization Expense	'
	As of September 27, 2013, future estimated amortization expense is expected to be as follows (in thousands):
			Amortization
			Expense
	2013 (remaining in year)		$	1,526
	2014			4,884
	2015			2,813
	2016			2,293
	2017			1,387
	2018			848
	2019			497
	Total		$	14,248

Income_Tax_Tables

Income Tax (Tables)	9 Months Ended
	Sep. 27, 2013
Income Tax Disclosure [Abstract]	'
Activity Related to Company's Uncertain Tax Positions	'
	The following table summarizes the activity related to the Company’s uncertain tax positions (in thousands):
		Nine months ended
		September 27,			September 28,
		2013			2012
	Balance as of the beginning of period	$	109		$	132
	Finalization of tax audits		—			(21	)
	Decreases related to prior year tax positions		(22	)		—
	Balance as of the end of period	$	87		$	111

Net_Income_Per_Share_Tables

Net Income Per Share (Tables)	9 Months Ended
	Sep. 27, 2013
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 27,		September 28,			September 27,		September 28,
		2013		2012			2013		2012
	Net income	$	2,048	$	(1,123	)	$	4,053	$	6,327
	Denominator:
	Shares used in computation — basic:
	Weighted average common shares outstanding		28,451		27,656			28,265		24,851
	Shares used in computation — diluted:
	Shares used in computing basic net income per share		28,451		27,656			28,265		24,851
	Dilutive effect of common shares outstanding subject to repurchase		241					365		265
	Dilutive effect of options outstanding		287					249		377
	Weighted average shares used in computing diluted net income per share		28,979		27,656			28,879		25,493
	Net income per share — basic	$	0.07	$	(0.04	)	$	0.14	$	0.25
	Net income per share — diluted	$	0.07	$	(0.04	)	$	0.14	$	0.25

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 27, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Summary of Future Minimum Payments under Operating Leases	'
	As of September 27, 2013, future minimum payments under these operating leases were as follows (in thousands):
	Fiscal year
	2013 (remaining in year)	$	1,330
	2014		5,108
	2015		4,577
	2016		3,952
	2017		3,347
	Thereafter		9,485
	Total minimum lease payments	$	27,799

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 27, 2013
Segment Reporting [Abstract]	'
Revenue by Geographic Area	'
	The following table sets forth revenue by geographic area (in thousands):
		Three months ended				Nine months ended
		Sept 27,		Sept 28,		Sept 27,		Sept 28,
		2013		2012		2013		2012
	United States	$	76,388	$	84,437	$	244,476	$	239,716
	China		10,521		6,033		24,954		20,939
	Singapore		17,602		9,908		40,094		50,145
	Other		2,672		471		8,230		2,563
		$	107,183	$	100,849	$	317,754	$	313,363

Correction_of_Previously_Repor1

Correction of Previously Reported Quarterly Financial Statements (Tables)	9 Months Ended
	Sep. 27, 2013
Accounting Changes And Error Corrections [Abstract]	'
Schedule of Corrections to 2012 Interim Financial Statements	'
	The Company has included such corrections to its 2012 interim financial statements for the periods ended September 28, 2012 within this report on Form 10-Q.
			Three Months			Corrections to			Three months			Nine months		Corrections to			Nine months
			ended			the  three			ended			ended		the  nine			ended
			September 28,			months ended			September 28,			September 28,		months ended			September 28,
			2012 as			September 28, 2012			2012 as			2012 as		September 28, 2012			2012 as
			reported						corrected			reported					corrected
			(In thousands, except per share data)
	Sales		$	100,849					$	100,849		$	313,363				$	313,363
	Gross profit		$	14,323					$	14,323		$	44,237				$	44,237
	Operating expenses		$	15,750		$	(761	)(a)(b)	$	14,989		$	34,481	$	(307	)(b)	$	34,174
	Income from operations		$	(1,427	)	$	761		$	(666	)	$	9,756	$	307		$	10,063
	Income tax provision		$	(539	)	$	183	(c)	$	(356	)	$	1,942	$	862	(c)(d)	$	2,804
	Net income (loss)		$	(1,701	)	$	578		$	(1,123	)	$	6,882	$	(555	)	$	6,327
	Earnings per share — basic		$	(0.06	)	$	0.02		$	(0.04	)	$	0.28	$	(0.03	)	$	0.25
	Earnings per share — diluted		$	(0.06	)	$	0.02		$	(0.04	)	$	0.27	$	(0.02	)	$	0.25
	The corrections relate to:
	a)	$454,000 of costs associated with the acquisition of AIT that were capitalized at June 29, 2012 and expensed in the quarter ended September 28, 2012, which should have been expensed in the quarter ended June 29, 2012;
	b)	$307,000 of performance equity award expenses originally reversed in the quarter ended December 28, 2012, that should have been reversed in the quarter ended September 28, 2012;
	c)	the tax effect of items a) and b) above; and,
	d)	foreign tax payments of $770,000 that were recorded as a reduction of other current liabilities as of September 28, 2012 and expensed in the quarter ended December 28, 2012 but should have been expensed in the quarter ended June 29, 2012.

Organization_and_Significant_A3

Organization and Significant Accounting Policies - Additional Information (Detail) (USD $)

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 27, 2013

Dec. 28, 2012

Sep. 28, 2012

Dec. 30, 2011

Sep. 27, 2013

Sep. 27, 2013

Dec. 28, 2012

Sep. 27, 2013

Sep. 27, 2013

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Dec. 28, 2012

Segment

Maximum [Member]

Subsidiaries [Member]

Subsidiaries [Member]

Money Market Funds [Member]

Money Market Funds [Member]

Sales Revenue, Net [Member]

Sales Revenue, Net [Member]

Sales Revenue, Net [Member]

Sales Revenue, Net [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

China [Member]

China [Member]

Level 2 [Member]

Customer

Customer

Customer

Customer

Customer

Customer

ASM International [Member]

ASM International [Member]

Concentration Risk [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of customers equal or exceeding 10 % threshold

'

'

'

'

'

'

'

'

'

3

3

3

2

3

3

'

'

Accounts receivable balances, aggregate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

79.00%

84.00%

Carrying value of cash and cash equivalent

$65,941,000

$54,311,000

$58,329,000

$52,155,000

'

'

'

$17,900,000

'

'

'

'

'

'

'

'

'

Fair value of cash and cash equivalent

'

'

'

'

'

'

'

'

17,900,000

'

'

'

'

'

'

'

'

Fiscal Year Duration

'52-53 week

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Valuation allowance on deferred tax assets

'

'

'

'

'

$851,000

$851,000

'

'

'

'

'

'

'

'

'

'

Product warranty period (in years)

'

'

'

'

'2 years

'

'

'

'

'

'

'

'

'

'

'

'

Number of reporting segment

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Measurement period to determine fair value of assets and liabilities

'

'

'

'

'12 months

'

'

'

'

'

'

'

'

'

'

'

'

Organization_and_Significant_A4

Organization and Significant Accounting Policies - Customers as Percentage of Total Sales (Detail) (Sales [Member])	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Concentration Risk [Line Items]	'	'	'	'
Total	81.10%	76.40%	79.70%	74.00%
Applied Materials, Inc. [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Total	32.90%	29.40%	33.10%	39.60%
Lam Research Corporation [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Total	37.40%	27.50%	33.20%	34.40%
ASM International [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Total	10.80%	19.50%	13.40%	'

Organization_and_Significant_A5

Organization and Significant Accounting Policies - Components in Reserve for Warranty Costs (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Standard Product Warranty Disclosure [Abstract]	'	'
Beginning balance	$152	$350
Change in reserve	70	-4
Warranty claims	-119	-112
Ending balance	$103	$234

Organization_and_Significant_A6

Organization and Significant Accounting Policies - Additional Information1 (Detail) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Sep. 28, 2012

Jun. 29, 2012

Mar. 30, 2012

Sep. 27, 2013

Sep. 27, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 30, 2012

Inventory [Member]

Inventory [Member]

Employee Stock Option [Member]

Employee Stock Option [Member]

Employee Stock Option [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Awards [Member]

Employee Stock [Member]

Performance Shares [Member]

Performance Shares [Member]

Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Vesting period, weighted average, in years

'

'

'

'

'

'

'4 years

'

'

'

'

'

'

'

'

'3 years

'1 year

'

'

'

Expiration period, years

'

'

'

'

'

'

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

Number of options granted

'

'

'

'

'

'

0

0

'

'

'

'

'

'

'

'

'

'

'

'

Stock-based compensation cost, net of forfeitures, recognized

'

'

'

'

'

'

$100,000

'

'

'

'

'

'

'

'

$5,600,000

$100,000

'

'

'

Employee common stock fair market value rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

95.00%

'

'

Granted stock units

'

'

'

'

'

'

'

'

'

149,950

408,000

193,200

6,000

4,450

548,900

'

'

'

152,750

110,375

Weighted average fair value, granted

'

'

'

'

'

'

'

'

'

$6.87

$6.06

$5.39

$6.06

$6.41

$8.21

'

'

'

'

'

Vested shares withheld to satisfy withholding tax obligations

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

95,457

'

'

'

'

Vested shares issued net of tax withholdings

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

440,647

'

'

'

'

Outstanding restricted stock units

'

'

'

'

'

'

'

'

'

1,263,633

'

'

'

'

'

1,263,633

'

'

'

'

Aggregate intrinsic value

'

'

'

'

'

'

'

'

'

8,800,000

'

'

'

'

'

8,800,000

'

'

'

'

Weighted average remaining contractual term (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'1 year 2 months 12 days

'

'

'

'

Allocated stock-based compensation expenses, capitalized

$953,000

$1,076,000

$2,801,000

$3,140,000

$0

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Organization_and_Significant_A7

Organization and Significant Accounting Policies - Summary of Information with Respect to Options Granted, Exercised and Canceled (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 27, 2013	Dec. 28, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'
Outstanding, Number of Shares, Beginning balance	1,514,113	'
Granted, Number of Shares	'	'
Exercised, Number of Shares	-111,657	'
Canceled, Number of Shares	-38,173	'
Outstanding, Number of Shares, Ending balance	1,364,283	1,514,113
Vested and expected to vest, Number of Shares	1,364,274	'
Vested and exercisable, Number of Shares	1,363,885	'
Weighted Average Exercise Price Outstanding, Beginning balance	$6.98	'
Granted, Weighted Average Exercise Price	'	'
Exercised, Weighted Average Exercise Price	$1.15	'
Canceled, Weighted Average Exercise Price	$11.73	'
Weighted Average Exercise Price Outstanding, Ending balance	$7.32	$6.98
Vested and expected to vest, Weighted Average Exercise Price	$7.32	'
Vested and exercisable, Weighted Average Exercise Price	$7.32	'
Weighted Average Remaining Contractual Term, outstanding	'	'4 years
Vested and expected to vest, Weighted Average Contractual Term (years)	'	'
Vested and exercisable, Weighted Average Contractual Term (years)	'	'
Aggregate Intrinsic Value, outstanding, Beginning balance	$1,444,653	'
Aggregate Intrinsic Value, outstanding, Ending balance	2,112,313	1,444,653
Aggregate Intrinsic Value, Vested and expected to vest	2,112,310	'
Aggregate Intrinsic Value, Vested and exercisable	$2,112,174	'

Organization_and_Significant_A8

Organization and Significant Accounting Policies - Restricted Stock Unit and Restricted Stock Award Activity (Detail) (Restricted Stock Units and Restricted Stock Awards [Member])	9 Months Ended
	Sep. 27, 2013
Restricted Stock Units and Restricted Stock Awards [Member]	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'
Unvested restricted stock units and restricted stock awards, Beginning balance, shares	1,312,706
Granted, Number of Shares	786,150
Vested, Number of Shares	-566,104
Forfeited, Number of Shares	-238,185
Unvested restricted stock units and restricted stock awards, Ending balance, shares	1,294,567

Organization_and_Significant_A9

Organization and Significant Accounting Policies - Stock-Based Compensation Expense Included in Condensed Consolidated Statements of Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation	$1,126,000	$1,417,000	$3,511,000	$3,846,000
Income tax benefit	-173,000	-341,000	-644,000	-926,000
Total stock-based compensation expense, net of income tax benefit	953,000	1,076,000	2,801,000	3,140,000
Cost of Sales [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation	159,000	422,000	883,000	1,237,000
Research and development [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation	69,000	91,000	216,000	256,000
Sales and marketing [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation	127,000	118,000	356,000	324,000
General and administrative [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation	$771,000	$786,000	$1,990,000	$2,249,000

Balance_Sheet_Information_Summ

Balance Sheet Information - Summary of Inventory (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'	'
Raw materials	$41,031	$47,825
Work in process	14,109	9,994
Finished goods	2,098	2,349
Inventory, gross	57,238	60,168
Reserve for excess and obsolete	-6,945	-6,203
Total	$50,293	$53,965

Balance_Sheet_Information_Equi

Balance Sheet Information - Equipment and Leasehold Improvement, Net (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Equipment and leasehold improvements, gross	$41,136	$28,519
Accumulated depreciation	-32,380	-19,237
Total	8,756	9,282
Computer equipment and software [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Equipment and leasehold improvements, gross	9,216	8,148
Furniture and fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Equipment and leasehold improvements, gross	2,510	1,682
Machinery and equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Equipment and leasehold improvements, gross	15,638	8,597
Leasehold improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Equipment and leasehold improvements, gross	$13,772	$10,092

Acquisition_Additional_Informa

Acquisition - Additional Information (Detail) (USD $)	9 Months Ended				6 Months Ended	9 Months Ended		9 Months Ended
Share data in Millions, unless otherwise specified	Sep. 27, 2013	Jul. 03, 2012	Jul. 03, 2012	Jul. 03, 2012	Jun. 28, 2013	Sep. 27, 2013	Jul. 03, 2012	Sep. 28, 2012
		Senior Secured Credit Facility [Member]	Revolving Credit Facility [Member]	Term Loan Credit Facility [Member]	American Integration Technologies LLC [Member]	American Integration Technologies LLC [Member]	American Integration Technologies LLC [Member]	Ultra Clean and AIT [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Cash paid for acquisition of American Integration Technologies LLC	'	'	'	'	$75,300,000	'	'	'
Shares of newly issued common stock	'	'	'	'	4.5	'	'	'
Value of newly issued common stock	'	'	'	'	'	'	29,600,000	'
Total purchase price	'	'	'	'	104,890,000	'	104,900,000	'
Date of acquisition of American Integration Technologies LLC	'	'	'	'	3-Jul-12	'	'	'
Revolving credit facility balance	'	79,800,000	39,800,000	40,000,000	'	'	'	'
Spread to determine fair value of intangible assets	1.40%	'	'	'	'	'	'	'
Goodwill amortization period	'15 years	'	'	'	'	'	'	'
Rate utilized to discount estimated net cash flow on weighted average cost of capital	'	'	'	'	'	12.50%	'	'
Long term growth rate	'	'	'	'	'	4.00%	'	'
Acquisition related cost	'	'	'	'	'	'	'	$2,000,000

Acquisition_Purchase_Price_for

Acquisition - Purchase Price for Acquisitions (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012	Jun. 28, 2013	Jul. 03, 2012
In Thousands, unless otherwise specified			American Integration Technologies LLC [Member]	American Integration Technologies LLC [Member]
Business Acquisition [Line Items]	'	'	'	'
Cash and cash equivalents	'	'	$380	'
Accounts receivable	'	'	16,959	'
Inventories	'	'	23,618	'
Other current assets	'	'	381	'
Property and equipment	'	'	1,880	'
Goodwill	55,918	56,662	55,918	'
Purchased intangible assets	'	31,487	22,500	'
Total assets acquired	'	'	121,636	'
Accounts payable and accrued expenses	'	'	-13,807	'
Other liabilities	'	'	-2,939	'
Total liabilities assumed	'	'	-16,746	'
Purchase price allocated	'	'	$104,890	$104,900

Acquisition_Details_of_FiniteL

Acquisition - Details of Finite-Lived Intangible Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Dec. 28, 2012
Finite-Lived Intangible Assets [Line Items]	'	'	'	'	'
Total purchased intangible assets	$22,500	'	$22,500	'	'
Accumulated amortization	'	'	'	'	-3,785
Carrying amount	'	'	18,715	'	'
Amortization for intangibles	-1,500	-1,900	-4,467	-1,837	'
Carrying amount	14,248	'	14,248	'	'
Customer relationships [Member]	'	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'	'
Useful Life	'	'	'7 years	'	'
Total purchased intangible assets	19,000	'	19,000	'	'
Accumulated amortization	'	'	'	'	-3,448
Amortization for intangibles	'	'	-3,967	'	'
Tradename [Member]	'	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'	'
Useful Life	'	'	'6 years	'	'
Total purchased intangible assets	1,900	'	1,900	'	'
Intellectual Property/Know-How [Member]	'	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'	'
Useful Life	'	'	'7 years	'	'
Total purchased intangible assets	1,600	'	1,600	'	'
Accumulated amortization	'	'	'	'	-114
Amortization for intangibles	'	'	($170)	'	'

Acquisition_Unaudited_Pro_Form

Acquisition - Unaudited Pro Forma Consolidated Results of Operations (Detail) (Ultra Clean and AIT [Member], USD $)	3 Months Ended	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 28, 2012	Sep. 28, 2012
Ultra Clean and AIT [Member]	'	'
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]	'	'
Net sales	$100,849	$380,208
Net income	($177)	$9,312
Basic earnings per share	($0.01)	$0.33
Diluted earnings per share	($0.01)	$0.33

Goodwill_and_Purchased_Intangi2

Goodwill and Purchased Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Goodwill reduced	'	'	$700,000	'
Amortization Expenses	1,500,000	1,900,000	4,467,000	1,837,000
UCT Trade Name [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Value of UCT trade-name	'	'	9,000,000	'
Tradename [Member] | American Integration Technologies LLC [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization Expenses	'	'	330,000	'
Value of AIT trade-name	'	'	1,900,000	'
Life of AIT trade-name	'	'	'6 years	'
Tradename [Member] | Minimum [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Estimated economic life of intangible assets	'	'	'6 years	'
Tradename [Member] | Maximum [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Estimated economic life of intangible assets	'	'	'7 years	'
Customer relationships [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization Expenses	'	'	3,967,000	'
Estimated economic life of intangible assets	'	'	'7 years	'
Intellectual Property/Know-How [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization Expenses	'	'	$170,000	'
Intellectual Property/Know-How [Member] | Minimum [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Estimated economic life of intangible assets	'	'	'6 years	'
Intellectual Property/Know-How [Member] | Maximum [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Estimated economic life of intangible assets	'	'	'7 years	'

Goodwill_and_Purchased_Intangi3

Goodwill and Purchased Intangible Assets - Details of Goodwill (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Goodwill Impaired Accumulated Impairment Loss [Abstract]	'	'
Gross Amount	$89,961	$90,705
Accumulated Impairment	-34,043	-34,043
Net Carrying Amount	$55,918	$56,662

Goodwill_and_Purchased_Intangi4

Goodwill and Purchased Intangible Assets - Goodwill and Other Indefinite Lived Intangible Assets (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Intangible Assets Net Including Goodwill [Abstract]	'	'
Goodwill	$55,918	$56,662
Intangible Assets	23,235	27,702
Total	$79,153	$84,364

Goodwill_and_Purchased_Intangi5

Goodwill and Purchased Intangible Assets - Summary of Purchased Intangible Assets (Detail) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Dec. 28, 2012

Sep. 27, 2013

Dec. 28, 2012

Sep. 27, 2013

Sep. 27, 2013

Dec. 28, 2012

Jun. 28, 2013

Sep. 27, 2013

Dec. 28, 2012

Sep. 27, 2013

Dec. 28, 2012

Customer relationships [Member]

Customer relationships [Member]

Tradename [Member]

Intellectual Property/Know-How [Member]

Intellectual Property/Know-How [Member]

American Integration Technologies LLC [Member]

American Integration Technologies LLC [Member]

American Integration Technologies LLC [Member]

UCT [Member]

UCT [Member]

Tradename [Member]

Tradename [Member]

Tradename [Member]

Tradename [Member]

Finite-Lived Intangible Assets [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Purchased intangible assets

'

'

'

'

$31,487

'

$19,000

'

'

$1,600

$22,500

'

$1,900

'

$8,987

Accumulated amortization

'

'

'

'

-3,785

'

-3,448

'

'

-114

'

'

-223

'

'

Carrying Value

23,235

'

23,235

'

27,702

11,585

15,552

'

1,316

1,486

'

1,347

1,677

8,987

8,987

Amortization

($1,500)

($1,900)

($4,467)

($1,837)

'

($3,967)

'

'

($170)

'

'

($330)

'

'

'

Estimated Useful Life (in years)

'

'

'

'

'

'7 years

'

'6 years

'7 years

'

'

'6 years

'

'

'

Goodwill_and_Purchased_Intangi6

Goodwill and Purchased Intangible Assets - Future Estimated Amortization Expense (Detail) (USD $)	Sep. 27, 2013	Dec. 28, 2012
In Thousands, unless otherwise specified
Finite Lived Intangible Assets Future Amortization Expense [Abstract]	'	'
2013 (remaining in year)	$1,526	'
2014	4,884	'
2015	2,813	'
2016	2,293	'
2017	1,387	'
2018	848	'
2019	497	'
Total	$14,248	$18,715

Borrowing_Arrangements_Additio

Borrowing Arrangements - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 27, 2013	Jul. 03, 2012
Debt Instrument [Line Items]	'	'
Base rate interest	3.75%	'
Deferred interest	$1,900,000	'
Minimum domestic cash balance on last day for any quarters to be maintained to comply with credit agreement	15,000,000	'
Minimum domestic cash balance on last day for any month to be maintained to comply with credit agreement	10,000,000	'
Minimum consolidated adjusted EBITDA for last two quarters of 2012	3,500,000	'
Minimum consolidated adjusted EBITDA for the first quarters of 2013	2,500,000	'
Minimum consolidated adjusted EBITDA for the second quarter of 2013	3,000,000	'
Minimum consolidated adjusted EBITDA for the third quarter of 2013	4,000,000	'
Minimum consolidated adjusted EBITDA for the fourth quarter of 2013	6,000,000	'
Minimum consolidated adjusted EBITDA for the first quarters of 2014	7,000,000	'
Minimum consolidated adjusted EBITDA after first quarter of 2014	8,000,000	'
Percentage of net cash proceeds of subsidiary capital stock for debt prepayment	50.00%	'
Percentage of net cash proceeds of subsidiary capital stock for debt prepayment indebtedness amount over by specific amount	100.00%	'
Debt specific amount under prepayment condition of indebtedness	250,000	'
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%	'
Total debt, net of issuance cost	56,500,000	'
Term Loan [Member]	'	'
Debt Instrument [Line Items]	'	'
Term Loan	30,000,000	'
Unamortized debt issuance cost	1,300,000	'
Minimum [Member]	'	'
Debt Instrument [Line Items]	'	'
Fixed charge coverage ratio for the fiscal year	1	'
Fixed charge coverage ratio for the next fiscal year	1	'
Consolidated leverage ratio for third quarter of fiscal year	1	'
Consolidated leverage ratio for fourth quarter of fiscal year	1	'
Consolidated leverage ratio for third quarter of next year	1	'
Consolidated Leverage Ratio thereafter third quarter of next year	1	'
Minimum consolidated quick ratio	1	'
Term loan principal amount outstanding condition two	10,000,000	'
Maximum [Member]	'	'
Debt Instrument [Line Items]	'	'
Fixed charge coverage ratio for the fiscal year	1.1	'
Fixed charge coverage ratio for the next fiscal year	1.25	'
Consolidated leverage ratio for third quarter of fiscal year	4	'
Consolidated leverage ratio for fourth quarter of fiscal year	3.75	'
Consolidated leverage ratio for third quarter of next year	3.75	'
Consolidated Leverage Ratio thereafter third quarter of next year	3.25	'
Minimum consolidated quick ratio	1.1	'
Term loan principal amount outstanding condition two	20,000,000	'
Term Loan Credit Facility [Member]	'	'
Debt Instrument [Line Items]	'	'
Borrowing capacity under credit facility	'	40,000,000
Outstanding amount of borrowing under credit facility	'	40,000,000
Term loan repaid	2,500,000	'
Term Loan Credit Facility [Member] | Matures On July 03, 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Maturity date of debt	3-Jul-16	'
Revolving Credit Facility [Member]	'	'
Debt Instrument [Line Items]	'	'
Borrowing capacity under credit facility	'	40,000,000
Outstanding amount of borrowing under credit facility	'	39,800,000
Line of credit facility maturity period	'4 years	'
Term Loan	26,500,000	'
Bank Loan [Member]	'	'
Debt Instrument [Line Items]	'	'
Repay outstanding balance to silicon valley bank	3,700,000	'
Letter of Credit [Member]	'	'
Debt Instrument [Line Items]	'	'
Borrowing capacity under credit facility	'	15,000,000
Swingline Sub-Facility [Member]	'	'
Debt Instrument [Line Items]	'	'
Borrowing capacity under credit facility	'	$4,000,000

Income_Tax_Additional_Informat

Income Tax - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Dec. 28, 2012	Dec. 30, 2011
Income Tax Disclosure [Line Items]	'	'	'	'	'	'
Income tax provision	$375,000	($356,000)	$931,000	$2,804,000	'	'
Effective tax rate	15.50%	24.10%	18.70%	30.70%	'	'
Income tax provision on undistributed foreign earnings	'	'	0	'	'	'
Liability for unrecognized tax benefit	87,000	111,000	87,000	111,000	109,000	132,000
Interest related to certain tax position	3,000	3,000	3,000	3,000	'	'
Singapore Subsidiary [Member]	'	'	'	'	'	'
Income Tax Disclosure [Line Items]	'	'	'	'	'	'
Income tax holiday termination year	'	'	'Beginning January 2015	'	'	'
China Subsidiary [Member]	'	'	'	'	'	'
Income Tax Disclosure [Line Items]	'	'	'	'	'	'
Valuation allowance on deferred tax assets	$851,000	'	$851,000	'	'	'

Income_Tax_Activity_Related_to

Income Tax - Activity Related to Company's Uncertain Tax Positions (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns [Abstract]	'	'
Balance as of the beginning of period	$109	$132
Finalization of tax audits	'	-21
Decreases related to prior year tax positions	-22	'
Balance as of the end of period	$87	$111

Net_Income_Per_Share_Basic_and

Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Earnings Per Share [Abstract]	'	'	'	'
Net income	$2,048	($1,123)	$4,053	$6,327
Shares used in computation - basic:	'	'	'	'
Weighted average common shares outstanding	28,451	27,656	28,265	24,851
Shares used in computation - diluted:	'	'	'	'
Shares used in computing basic net income per share	28,451	27,656	28,265	24,851
Dilutive effect of common shares outstanding subject to repurchase	241	'	365	265
Dilutive effect of options outstanding	287	'	249	377
Weighted average shares used in computing diluted net income per share	28,979	27,656	28,879	25,493
Net income per share - basic	$0.07	($0.04)	$0.14	$0.25
Net income per share - diluted	$0.07	($0.04)	$0.14	$0.25

Net_Income_Per_Share_Additiona

Net Income Per Share - Additional Information (Detail) (Employee Stock Option [Member])	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Employee Stock Option [Member]	'	'	'	'
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share	575,470	1,013,361	996,495	612,069

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (Inventories [Member], USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013
Inventories [Member]	'
Long-term Purchase Commitment [Line Items]	'
Purchase commitment	$52.50

Commitments_and_Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Payments under Operating Leases (Detail) (USD $)	Sep. 27, 2013
In Thousands, unless otherwise specified
Operating Leases Future Minimum Payments Due [Abstract]	'
2013 (remaining in year)	$1,330
2014	5,108
2015	4,577
2016	3,952
2017	3,347
Thereafter	9,485
Total minimum lease payments	$27,799

Segment_Information_Additional

Segment Information - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 27, 2013	Sep. 28, 2012
	Segment	Asia [Member]	United States [Member]
Segment Reporting Information [Line Items]	'	'	'
Number of reporting segment	1	'	'
Net long-lived assets	'	$4.50	$4.20

Segment_Information_Revenue_by

Segment Information - Revenue by Geographic Area (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Segment Reporting Information [Line Items]	'	'	'	'
Sales	$107,183	$100,849	$317,754	$313,363
United States [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales	76,388	84,437	244,476	239,716
China [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales	10,521	6,033	24,954	20,939
Singapore [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales	17,602	9,908	40,094	50,145
Other [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales	$2,672	$471	$8,230	$2,563

Correction_of_Previously_Repor2

Correction of Previously Reported Quarterly Financial Statements - Schedule of Corrections to 2012 Interim Financial Statements (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Sales	$107,183	$100,849	$317,754	$313,363
Gross profit	15,833	14,323	45,759	44,237
Operating expenses	12,442	14,989	38,119	34,174
Income from operations	3,391	-666	7,640	10,063
Income tax provision	375	-356	931	2,804
Net income (loss)	2,048	-1,123	4,053	6,327
Earnings per share-basic	$0.07	($0.04)	$0.14	$0.25
Earnings per share-diluted	$0.07	($0.04)	$0.14	$0.25
As Reported [Member]	'	'	'	'
Sales	'	100,849	'	313,363
Gross profit	'	14,323	'	44,237
Operating expenses	'	15,750	'	34,481
Income from operations	'	-1,427	'	9,756
Income tax provision	'	-539	'	1,942
Net income (loss)	'	-1,701	'	6,882
Earnings per share-basic	'	($0.06)	'	$0.28
Earnings per share-diluted	'	($0.06)	'	$0.27
Corrections [Member]	'	'	'	'
Operating expenses	'	-761	'	-307
Income from operations	'	761	'	307
Income tax provision	'	183	'	862
Net income (loss)	'	$578	'	($555)
Earnings per share-basic	'	$0.02	'	($0.03)
Earnings per share-diluted	'	$0.02	'	($0.02)

Correction_of_Previously_Repor3

Correction of Previously Reported Quarterly Financial Statements - Schedule of Corrections to 2012 Interim Financial Statements (Parenthetical) (Detail) (USD $)	3 Months Ended
	Dec. 28, 2012	Jun. 29, 2012
Accounting Changes And Error Corrections [Abstract]	'	'
Costs associated with acquisition of AIT	'	$454,000
Cost of acquisition	307,000	'
Foreign tax payments	'	$770,000