FormFactor (FORM) 10-Q 30 Jul 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 26, 2021	Jul. 27, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 26, 2021
Document Transition Report	false
Entity File Number	000-50307
Entity Registrant Name	FormFactor, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3711155
Entity Address, Address Line One	7005 Southfront Road
Entity Address, City or Town	Livermore
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94551
City Area Code	925
Local Phone Number	290-4000
Title of 12(b) Security	Common stock, $0.001 par value
Trading Symbol	FORM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		77,674,960
Amendment Flag	false
Entity Central Index Key	0001039399
Current Fiscal Year End Date	--12-25
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Current assets:
Cash and cash equivalents	$ 160,273	$ 187,225
Marketable securities	95,962	67,810
Accounts receivable, net of allowance for doubtful accounts of $217 and $248	108,265	107,603
Inventories, net	111,890	99,229
Restricted cash	1,857	1,904
Prepaid expenses and other current assets	19,244	23,303
Total current assets	497,491	487,074
Restricted cash	1,836	1,969
Operating lease, right-of-use-assets	38,485	30,756
Property, plant and equipment, net of accumulated depreciation	125,348	104,103
Goodwill	214,548	212,761
Intangibles, net	41,913	59,147
Deferred tax assets	66,945	66,242
Other assets	1,980	1,165
Total assets	988,546	963,217
Current liabilities:
Accounts payable	62,445	62,045
Accrued liabilities	51,487	55,342
Current portion of term loans, net of unamortized issuance costs	9,356	9,516
Deferred revenue	22,655	20,964
Operating lease liabilities	7,908	6,704
Total current liabilities	153,851	154,571
Term loans, less current portion, net of unamortized issuance costs	20,123	24,978
Deferred tax liabilities	4,613	5,346
Long-term operating lease liabilities	34,211	27,996
Other liabilities	6,201	6,242
Total liabilities	218,999	219,133
Stockholders’ equity:
Common stock, $0.001 par value	77	78
Additional paid-in capital	894,062	903,838
Accumulated other comprehensive income	3,596	5,886
Accumulated deficit	(128,188)	(165,718)
Total stockholders’ equity	769,547	744,084
Total liabilities and stockholders’ equity	$ 988,546	$ 963,217

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 217	$ 248
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	77,454,800	77,437,997
Common stock, shares outstanding (in shares)	77,454,800	77,437,997

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Income Statement [Abstract]
Revenues	$ 188,076	$ 157,824	$ 374,712	$ 318,577
Cost of revenues	111,793	91,657	221,723	185,020
Gross profit	76,283	66,167	152,989	133,557
Operating expenses:
Research and development	25,454	20,919	49,500	42,186
Selling, general and administrative	30,479	22,755	60,494	50,448
Total operating expenses	55,933	43,674	109,994	92,634
Operating income	20,350	22,493	42,995	40,923
Interest income	148	376	342	1,061
Interest expense	(116)	(171)	(296)	(489)
Other expense, net	(194)	(67)	(22)	(158)
Income before income taxes	20,188	22,631	43,019	41,337
Provision for income taxes	2,283	2,162	5,489	4,978
Net income	$ 17,905	$ 20,469	$ 37,530	$ 36,359
Net income per share:
Basic (in dollars per share)	$ 0.23	$ 0.27	$ 0.48	$ 0.48
Diluted (in dollars per share)	$ 0.23	$ 0.26	$ 0.47	$ 0.46
Weighted-average number of shares used in per share calculations:
Basic (in shares)	77,463	76,275	77,530	76,140
Diluted (in shares)	79,466	78,861	79,621	78,710

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 17,905	$ 20,469	$ 37,530	$ 36,359
Other comprehensive income (loss), net of tax:
Translation adjustments and other	632	763	(1,747)	364
Unrealized gains (losses) on available-for-sale marketable securities	(97)	524	(228)	497
Unrealized gains (losses) on derivative instruments	(89)	80	(315)	256
Other comprehensive income (loss), net of tax	446	1,367	(2,290)	1,117
Comprehensive income	$ 18,351	$ 21,836	$ 35,240	$ 37,476

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 28, 2019		75,764,990	0
Beginning balance at Dec. 28, 2019	$ 640,997	$ 76	$ 0	$ 885,821	$ (659)	$ (244,241)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		311,591
Issuance of common stock under the Employee Stock Purchase Plan	4,066			4,066
Issuance of common stock pursuant to exercise of options (in shares)		105,769
Issuance of common stock pursuant to exercise of options	869	$ 1		868
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax (in shares)		319,109
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax	(3,800)			(3,800)
Stock-based compensation	11,114			11,114
Other comprehensive income	1,117				1,117
Net income	36,359					36,359
Ending balance (in shares) at Jun. 27, 2020		76,501,459	0
Ending balance at Jun. 27, 2020	690,722	$ 77	$ 0	898,069	458	(207,882)
Beginning balance (in shares) at Mar. 28, 2020		76,158,251	0
Beginning balance at Mar. 28, 2020	666,417	$ 77	$ 0	895,600	(909)	(228,351)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options (in shares)		50,000
Issuance of common stock pursuant to exercise of options	422			422
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax (in shares)		293,208
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax	(3,415)			(3,415)
Stock-based compensation	5,462			5,462
Other comprehensive income	1,367				1,367
Net income	20,469					20,469
Ending balance (in shares) at Jun. 27, 2020		76,501,459	0
Ending balance at Jun. 27, 2020	690,722	$ 77	$ 0	898,069	458	(207,882)
Beginning balance (in shares) at Dec. 26, 2020		77,437,997	0
Beginning balance at Dec. 26, 2020	744,084	$ 78	$ 0	903,838	5,886	(165,718)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		228,784
Issuance of common stock under the Employee Stock Purchase Plan	5,065			5,065
Issuance of common stock pursuant to exercise of options (in shares)		100,000
Issuance of common stock pursuant to exercise of options	844			844
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax (in shares)		308,219
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax	(5,261)			(5,261)
Purchase of common stock retired through repurchase program (in shares)		620,200
Purchase and retirement of common stock through repurchase program	(23,951)	$ (1)		(23,950)
Stock-based compensation	13,526			13,526
Other comprehensive income	(2,290)				(2,290)
Net income	37,530					37,530
Ending balance (in shares) at Jun. 26, 2021		77,454,800	0
Ending balance at Jun. 26, 2021	769,547	$ 77	$ 0	894,062	3,596	(128,188)
Beginning balance (in shares) at Mar. 27, 2021		77,758,530	(136,402)
Beginning balance at Mar. 27, 2021	766,533	$ 78	$ (5,738)	915,136	3,150	(146,093)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options (in shares)		50,000
Issuance of common stock pursuant to exercise of options	422			422
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax (in shares)		266,470
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld for tax	(4,120)			(4,120)
Purchase of common stock retired through repurchase program (in shares)		620,200	136,402
Purchase and retirement of common stock through repurchase program	(18,213)	$ (1)	$ 5,738	(23,950)
Stock-based compensation	6,574			6,574
Other comprehensive income	446				446
Net income	17,905					17,905
Ending balance (in shares) at Jun. 26, 2021		77,454,800	0
Ending balance at Jun. 26, 2021	$ 769,547	$ 77	$ 0	$ 894,062	$ 3,596	$ (128,188)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020
Cash flows from operating activities:
Net income	$ 37,530	$ 36,359
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,678	9,240
Amortization	13,900	13,717
Reduction in the carrying amount of right-of-use assets	3,652	2,419
Stock-based compensation expense	13,665	11,265
Provision for excess and obsolete inventories	6,898	6,407
Gain on contingent consideration	(95)	(3,700)
Other adjustments to reconcile net income to net cash provided by operating activities	1,211	1,327
Changes in assets and liabilities:
Accounts receivable	(1,194)	11,364
Inventories	(20,388)	(11,089)
Prepaid expenses and other current assets	3,179	(3,271)
Other assets	(344)	248
Accounts payable	(2,028)	5,247
Accrued liabilities	(235)	1,529
Other liabilities	184	292
Deferred revenues	1,522	3,855
Operating lease liabilities	(3,980)	(2,762)
Net cash provided by operating activities	66,155	82,447
Cash flows from investing activities:
Acquisition of property, plant and equipment	(31,322)	(36,743)
Proceeds from sale of a subsidiary	0	82
Purchases of marketable securities	(71,186)	(19,726)
Proceeds from maturities and sales of marketable securities	42,695	35,410
Net cash used in investing activities	(59,813)	(20,977)
Cash flows from financing activities:
Proceeds from issuances of common stock	5,909	4,935
Purchase of common stock through stock repurchase program	(23,951)	0
Tax withholdings related to net share settlements of equity awards	(5,261)	(3,800)
Payment of contingent consideration	(3,873)	0
Proceeds from term loan debt	0	18,000
Principal repayments on term loans	(4,740)	(26,322)
Payment of term loan debt issuance costs	0	(78)
Net cash used in financing activities	(31,916)	(7,265)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,558)	583
Net increase (decrease) in cash, cash equivalents and restricted cash	(27,132)	54,788
Cash, cash equivalents and restricted cash, beginning of period	191,098	147,937
Cash, cash equivalents and restricted cash, end of period	163,966	202,725
Non-cash investing and financing activities:
Increase (decrease) in accounts payable and accrued liabilities related to property, plant and equipment purchases	2,906	(2,274)
Operating lease, right-of-use assets obtained in exchange for lease obligations	11,629	428
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	4,559	4,133
Cash paid for interest	339	473
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	160,273	199,926
Restricted cash, current	1,857	1,424
Restricted cash, non-current	1,836	1,375
Total cash, cash equivalents and restricted cash	$ 163,966	$ 202,725

Basis of Presentation and New A

Basis of Presentation and New Accounting Pronouncements	6 Months Ended
	Jun. 26, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and New Accounting Pronouncements	Basis of Presentation and New Accounting Pronouncements Basis of Presentation The accompanying condensed consolidated financial information of FormFactor, Inc. is unaudited and has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). However, such information reflects all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 22, 2021. The results of operations for the interim periods presented are not necessarily indicative of the results to be expected for the full year. Fiscal Year We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2021 and 2020 each contain 52 weeks and the six months ended June 26, 2021 and June 27, 2020 each contained 26 weeks. Fiscal 2021 will end on December 25, 2021. Significant Accounting Policies Our significant accounting policies have not changed during the six months ended June 26, 2021 from those disclosed in our Annual Report on Form 10-K for the year ended December 26, 2020. New Accounting Pronouncements ASU 2019-12 In December 2019, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, “Income Taxes (Topic 740),” which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 on a prospective basis on December 27, 2020, the first day of fiscal 2021. The adoption did not have a material effect on our consolidated financial position, results of operations or cash flows. ASU 2020-04 In March 2020, the FASB issued ASU 2020-04, “Referenced Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU provides temporary optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform (Topic 848),” which permits entities to apply optional expedients in Topic 848 to derivative instruments modified because of discounting transition resulting from reference rate reform. ASU 2020-04 became effective upon issuance and may be applied prospectively to contract modifications made on or before December 31, 2022. ASU 2021-01 became effective upon issuance and may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or prospectively for contract modifications made on or before December 31, 2022. The Company has not yet applied the relief afforded by these standard amendments and is currently assessing contracts that will require modification due to reference rate reform to which these standard amendments may be applied.

Concentration of Credit and Oth

Concentration of Credit and Other Risks	6 Months Ended
	Jun. 26, 2021
Risks and Uncertainties [Abstract]
Concentration of Credit and Other Risks	Concentration of Credit and Other Risks Each of the following customers accounted for 10% or more of our revenues for the periods indicated: Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Intel Corporation 16.2 % 36.1 % 22.1 % 36.2 % Samsung Electronics., LTD. 14.7 % * * * Taiwan Semiconductor Manufacturing Co., LTD. 11.0 % * 11.2 % * 41.9 % 36.1 % 33.3 % 36.2 % *Represents less than 10% of total revenues.

Inventories, net

Inventories, net	6 Months Ended
	Jun. 26, 2021
Inventory Disclosure [Abstract]
Inventories, net	Inventories, net Inventories are stated at the lower of cost (principally standard cost, which approximates actual cost on a first in, first out basis) or net realizable value. Inventories, net, consisted of the following (in thousands): June 26, December 26, Raw materials $ 56,138 $ 48,122 Work-in-progress 35,911 30,806 Finished goods 19,841 20,301 $ 111,890 $ 99,229

Acquisition

Acquisition	6 Months Ended
	Jun. 26, 2021
Business Combination and Asset Acquisition [Abstract]
Acquisition	Acquisition High Precision Devices, Inc. Acquisition On October 19, 2020, we acquired 100% of the shares of HPD for total consideration of $16.9 million, net of cash acquired of $1.7 million, which included an adjustment for changes in working capital. This acquisition brings highly specialized skills and know-how to address the unique test challenges within the emerging quantum computing, superconducting computing, and ultra-sensitive sensor markets which operate at temperatures as low as 30 millikelvin. The acquisition was accounted for using the acquisition method of accounting, with FormFactor treated as the acquirer. The acquired assets and liabilities of HPD were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. Our Condensed Consolidated Statements of Income include the financial results of HPD subsequent to the acquisition date of October 19, 2020. Revenue in fiscal 2020 related to HPD subsequent to the acquisition date that was included in our Condensed Consolidated Statements of Income was not material. The acquisition price was allocated to the tangible and identified intangible assets acquired and liabilities assumed as of the closing date of the acquisition based upon their respective fair values. The fair values assigned to assets acquired and liabilities assumed were based on management’s assumptions as of the reporting date. We estimated the acquisition price and the allocation of fair value to assets acquired and liabilities assumed as of the acquisition date, October 19, 2020. We subsequently made certain immaterial adjustments within the measurement period to the preliminary acquisition price allocation. See Note 5, Goodwill and Intangible Assets , for changes in identified intangible values and goodwill. Our purchase accounting remains open at June 26, 2021, subject to finalization of certain deferred tax items. The estimated fair value of assets acquired, including goodwill and intangibles, and liabilities assumed is as follows (in thousands): Amount Cash and cash equivalents $ 1,680 Accounts receivable 1,017 Inventories 3,047 Property, plant and equipment 669 Operating lease, right of use assets 2,554 Prepaid expenses and other current assets 599 Tangible assets acquired 9,566 Deferred revenue (2,529) Accounts payable and accrued liabilities (1,268) Operating lease liabilities (2,554) Deferred tax liabilities (2,840) Total tangible assets acquired and liabilities assumed 375 Intangible assets 11,520 Goodwill 6,665 Net Assets Acquired $ 18,560 The intangible assets as of the closing date of the acquisition included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 7,500 10.0 Customer relationships 3,600 5.0 Order backlog 200 0.5 Trade names 220 5.0 Total intangible assets $ 11,520 8.2 The fair value of the intangible assets acquired in connection with the acquisition was determined using either the income, market or replacement cost methodologies. The intangible assets are being amortized over periods which reflect the pattern in which economic benefits of the assets are expected to be realized. Identifiable Intangible Assets Valuation of intangible assets involves multiple assumptions. The key assumptions are described below. Developed technology acquired primarily consists of existing technology related to cryogenic probe stations, Adiabatic Demagnetization Refrigerator (“ADR”), and continuous ADR cryostats and similar tools, and technology related to other cryogenic applications. We valued the developed technology using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. The value of customer relationships represents the fair value of future projected revenues that will be derived from the sale of products to HPD's existing customers. We valued customer relationships using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the customers relationships in place on the acquisition date versus having no relationships in place and needing to replicate or replace those relationships. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. Order backlog represents the value of future sales under existing contracts as of the acquisition date. Expected cash flow from order backlog was valued on a discounted direct cash flow basis, net of returns on contributory assets such as working capital, property and equipment, trade name and assembled workforce. The identified trade names intangibles relate to the estimated fair value of future cash flows related to the HPD brand. We valued trade names by applying the relief-from-royalty method under the income approach. This method is based on the application of a royalty rate to forecasted revenue under the trade name. Goodwill The excess of purchase price over the fair value assigned to the assets acquired and liabilities assumed represents the amount of goodwill resulting from the acquisition. We believe the factors that contributed to goodwill include synergies that are specific to our consolidated business, such as cost savings and operational efficiencies, and the acquisition of a talented workforce that expands our expertise in business development and commercializing semiconductor test products, none of which qualify for recognition as a separate intangible asset. We do not expect any portion of this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition was recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The goodwill arising from the acquisition was allocated to the HPD reporting unit within the Systems reportable segment. We have not presented unaudited combined pro forma financial information as the HPD acquisition was not significant to our consolidated results of operations and financial position. Baldwin Park Acquisition On July 30, 2020, we acquired the probe card assets of Advantest Corporation for total cash consideration of $35.0 million. This acquisition brings important enabling technologies and capabilities for designing and manufacturing advanced probe cards, and adds a complementary 3D-NAND Flash probe-card product that is qualified and in production at one of the world's leading NAND Flash manufacturers. The acquisition was accounted for using the acquisition method of accounting, with FormFactor treated as the acquirer. The acquired assets and liabilities of Baldwin Park were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. Our Condensed Consolidated Statements of Income include the financial results of Baldwin Park subsequent to the acquisition date of July 30, 2020. Revenue related to Baldwin Park since the acquisition date that was included in our Condensed Consolidated Statements of Income for fiscal 2020 was not material. We estimated the acquisition price and the allocation of fair value to assets acquired and liabilities assumed as of the acquisition date, July 30, 2020. We subsequently made certain immaterial adjustments within the measurement period to the acquisition price allocation as a result of finalization of our valuation of identifiable assets and liabilities. See Note 5, Goodwill and Intangible Assets, for changes in identified intangible values and goodwill. The final allocation of the assets acquired, including goodwill and intangibles, and liabilities assumed for the purchase as follows (in thousands): Amount Accounts receivable $ 4,365 Inventories 2,727 Property, plant and equipment 9,053 Operating lease, right of use assets 519 Prepaid expenses and other current assets 56 Tangible assets acquired 16,720 Accounts payable and accrued liabilities (743) Operating lease liabilities (519) Total tangible assets acquired and liabilities assumed 15,458 Intangible assets 13,600 Goodwill 5,942 Net assets acquired $ 35,000 The intangible assets as of July 30, 2020 included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 8,800 10.0 Customer relationships 4,400 3.0 In-process research and development 400 N/A Total intangible assets $ 13,600 7.7 Indications of fair value of the intangible assets acquired in connection with the acquisition were determined using either the income, market or replacement cost methodologies. The intangible assets are being amortized over periods which reflect the pattern in which economic benefits of the assets are expected to be realized. Identifiable Intangible Assets Valuation of intangible assets involves multiple assumptions. The key assumptions are described below. Developed technology acquired consists of existing technology related to 3D NAND Flash probe cards and the value expected to be derived from interconnect technology. We valued the developed technology related to 3D NAND Flash using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. We valued the interconnect developed technology asset using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the interconnect capability in place on the acquisition date versus having no capability in place and needing to replicate or replace that capability. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. The value of customer relationships represents the fair value of future projected revenues that will be derived from the sale of products to Baldwin Park's existing customers. We valued customer relationships using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the customers relationships in place on the acquisition date versus having no relationships in place and needing to replicate or replace those relationships. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. In-process research and development (“IPR&D”) acquired primarily consists of research and development projects that were in process at the time of acquisition related to technologies used in DRAM probe cards. Once these projects are complete they will be amortized over their useful life. We valued the IPR&D using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. Goodwill The excess of purchase price over the fair value assigned to the assets acquired and liabilities assumed represents the amount of goodwill resulting from the acquisition. We believe the factors that contributed to goodwill include synergies that are specific to our consolidated business, such as cost savings and operational efficiencies, and the acquisition of a talented workforce that expands our expertise in business development, none of which qualify for recognition as a separate intangible asset. We expect this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition was recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The goodwill arising from the acquisition was allocated to the Probe Cards reporting unit within the Probe Cards reportable segment. We have not presented unaudited combined pro forma financial information as the Baldwin Park acquisition was not significant to our consolidated results of operations and financial position.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 26, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill by reportable segment was as follows (in thousands): Probe Cards Systems Total Goodwill, gross, as of December 28, 2019 $ 172,482 $ 26,714 $ 199,196 Addition - FRT GmbH Acquisition — 975 975 Addition - Baldwin Park Acquisition 5,590 — 5,590 Addition - HPD Acquisition — 4,654 4,654 Foreign currency translation — 2,346 2,346 Goodwill, gross, as of December 26, 2020 178,072 34,689 212,761 Addition - Baldwin Park Acquisition 352 — 352 Addition - HPD Acquisition — 2,011 2,011 Foreign currency translation — (576) (576) Goodwill, gross, as of July 26, 2021 $ 178,424 $ 36,124 $ 214,548 We have not recorded goodwill impairments for the six months ended June 26, 2021. Intangible assets were as follows (in thousands): June 26, 2021 December 26, 2020 Intangible Assets Gross Accumulated Net Gross Accumulated Net Developed technologies $ 173,627 $ 147,968 $ 25,659 $ 176,265 $ 137,754 $ 38,511 Customer relationships 51,641 36,437 15,204 52,488 33,378 19,110 Trade names 8,140 7,520 620 8,162 7,363 799 Order backlog 1,990 1,960 30 2,227 1,900 327 In-process research and development 400 — 400 400 — 400 $ 235,798 $ 193,885 $ 41,913 $ 239,542 $ 180,395 $ 59,147 Amortization expense was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Cost of revenues $ 5,505 $ 4,926 $ 10,595 $ 10,676 Selling, general and administrative 1,590 1,528 3,305 3,041 $ 7,095 $ 6,454 $ 13,900 $ 13,717 The estimated future amortization of definite-lived intangible assets, excluding in-process research and development, is as follows (in thousands): Fiscal Year Amount Remainder of 2021 $ 4,885 2022 9,647 2023 7,271 2024 4,652 2025 4,389 Thereafter 10,669 $ 41,513

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 26, 2021
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following (in thousands): June 26, December 26, Accrued compensation and benefits $ 31,210 $ 33,110 Accrued income and other taxes 6,049 6,976 Accrued warranty 4,258 3,918 Employee stock purchase plan contributions withheld 4,768 4,240 Accrued contingent consideration — 4,012 Other accrued expenses 5,202 3,086 $ 51,487 $ 55,342

Fair Value and Derivative Instr

Fair Value and Derivative Instruments	6 Months Ended
	Jun. 26, 2021
Fair Value Disclosures [Abstract]
Fair Value and Derivative Instruments	Fair Value and Derivative Instruments Whenever possible, the fair values of our financial assets and liabilities are determined using quoted market prices of identical securities or quoted market prices of similar securities from active markets. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 valuations are obtained from real-time quotes for transactions in active exchange markets involving identical securities; • Level 2 valuations utilize significant observable inputs, such as quoted prices for similar assets or liabilities, quoted prices near the reporting date in markets that are less active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and • Level 3 valuations utilize unobservable inputs to the valuation methodology and include our own data about assumptions market participants would use in pricing the asset or liability based on the best information available under the circumstances. We did not have any transfers of assets or liabilities measured at fair value on a recurring basis to or from Level 1, Level 2 or Level 3 during the three and six months ended June 26, 2021 or the year ended December 26, 2020. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and term loans, net of unamortized issuance costs, approximate fair value due to their short maturities. No changes were made to our valuation techniques during the first six months of fiscal 2021. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and liabilities measured at fair value on a recurring basis were as follows (in thousands): June 26, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 25,917 $ — $ — $ 25,917 Marketable securities: U.S. treasuries 27,112 — — 27,112 Certificates of deposit — 1,207 — 1,207 U.S. agency securities — 575 — 575 Corporate bonds — 28,893 — 28,893 Commercial paper — 38,175 — 38,175 27,112 68,850 — 95,962 Foreign exchange derivative contracts (Designated) — 152 — 152 Interest rate swap derivative contracts — 571 — 571 Total assets $ 53,029 $ 69,573 $ — $ 122,602 Liabilities: Foreign exchange derivative contracts (Designated) $ — $ (53) $ — $ (53) Interest rate swap derivative contracts — (103) — (103) Total liabilities $ — $ (156) $ — $ (156) December 26, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 43,019 $ — $ — $ 43,019 Marketable securities: U.S. treasuries 40,726 — — 40,726 Certificates of deposit — 2,179 — 2,179 U.S. agency securities — 575 — 575 Corporate bonds — 24,330 — 24,330 40,726 27,084 — 67,810 Foreign exchange derivative contracts — 1,057 — 1,057 Interest rate swap derivative contracts — 57 — 57 Total assets $ 83,745 $ 28,198 $ — $ 111,943 Liabilities: Interest rate swap derivative contracts $ — $ (87) $ — $ (87) Contingent consideration — — (4,012) (4,012) Total liabilities $ — $ (87) $ (4,012) $ (4,099) Cash Equivalents The fair value of our cash equivalents is determined based on quoted market prices for similar or identical securities. Marketable Securities We classify our marketable securities as available-for-sale and value them utilizing a market approach. Our investments are priced by pricing vendors who provide observable inputs for their pricing without applying significant judgment. Broker pricing is used mainly when a quoted price is not available, the investment is not priced by our pricing vendors or when a broker price is more reflective of fair value. Our broker-priced investments are categorized as Level 2 investments because fair value is based on similar assets without applying significant judgments. In addition, all investments have a sufficient trading volume to demonstrate that the fair value is appropriate. Unrealized gains and losses were immaterial and were recorded as a component of Accumulated other comprehensive income in our Condensed Consolidated Balance Sheets. We did not have any other-than-temporary unrealized gains or losses at either period end included in these financial statements. Contingent Consideration Contingent consideration, arising from the acquisition of FRT, was a cash amount equal to 1.5x EBIT as defined in the purchase agreement, up to a maximum of €10.3 million, payable subject to the performance of the acquired business in calendar 2020. We estimated the fair value of contingent consideration using a probability weighted approach. Key assumptions in determining the fair value of contingent consideration included estimating EBIT levels that we believed as of the acquisition date were likely to be achieved during the performance period and discounting at an appropriate discount rate. We settled our contingent consideration in the current quarter for $3.9 million, resulting in a $0.1 million credit to Selling, general and administrative expense with the remaining change from December 26, 2020 resulting from foreign currency translation. Interest Rate Swaps The fair value of our interest rate swap contracts is determined at the end of each reporting period based on valuation models that use interest rate yield curves as inputs. For accounting purposes, our interest rate swap contracts qualify for, and are designated as, cash flow hedges. The cash flows associated with the interest rate swaps are reported in Net cash provided by operating activities in our Condensed Consolidated Statements of Cash Flows and the fair value of the interest rate swap contracts are recorded within Accrued liabilities and Other liabilities in our Condensed Consolidated Balance Sheets. The impact of the interest rate swaps on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Three Months Ended June 26, 2021 $ (203) Interest expense $ (39) Interest expense $ — Three Months Ended June 27, 2020 $ (174) Interest expense $ (10) Interest expense $ — Six Months Ended June 26, 2021 $ 421 Interest expense $ (77) Interest expense $ — Six Months Ended June 27, 2020 $ (270) Interest expense $ 12 Interest expense $ — Foreign Exchange Derivative Contracts We operate and sell our products in various global markets. As a result, we are exposed to changes in foreign currency exchange rates. We utilize foreign currency forward contracts to hedge against future movements in foreign exchange rates that affect certain existing foreign currency denominated assets and liabilities and forecasted foreign currency revenue and expense transactions. Under this program, our strategy is to have increases or decreases in our foreign currency exposures mitigated by gains or losses on the foreign currency forward contracts in order to mitigate the risks and volatility associated with foreign currency transaction gains or losses. We do not use derivative financial instruments for speculative or trading purposes. For accounting purposes, certain of our foreign currency forward contracts are not designated as hedging instruments and, accordingly, we record the fair value of these contracts as of the end of our reporting period in our Condensed Consolidated Balance Sheets with changes in fair value recorded within Other expense, net in our Condensed Consolidated Statement of Income for both realized and unrealized gains and losses. Certain of our foreign currency forward contracts are designated as cash flow hedges, and, accordingly, we record the fair value of these contracts as of the end of our reporting period in our Condensed Consolidated Balance Sheets with changes in fair value recorded as a component of Accumulated other comprehensive income and reclassified into earnings in the same period in which the hedged transaction affects earnings, and in the same line item on the Condensed Consolidated Statements of Income as the impact of the hedge transaction. The fair value of our foreign exchange derivative contracts was determined based on current foreign currency exchange rates and forward points. All of our foreign exchange derivative contracts outstanding at June 26, 2021 will mature by the second quarter of fiscal 2022. The following table provides information about our foreign currency forward contracts outstanding as of June 26, 2021 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (12,678) $ (15,124) Japanese Yen Sell 1,802,229 16,251 Korean Won Buy (3,050,367) (2,703) Total USD notional amount of outstanding foreign exchange contracts $ (1,576) Our foreign currency contracts are classified within Level 2 of the fair value hierarchy as they are valued using pricing models that utilize observable market inputs. The impact of foreign exchange derivative contracts not designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized on Derivatives Three Months Ended Six Months Ended Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized on Derivatives June 26, June 27, June 26, June 27, Foreign exchange forward contracts Other expense, net $ (69) $ 234 $ 1,220 $ 349 The impact of foreign exchange derivative contracts designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Three Months Ended June 26, 2021 $ 278 Cost of revenues $ 134 Research and development 16 Selling, general and administrative 52 $ 202 Three Months Ended June 27, 2020 $ 52 Cost of revenues $ (139) Research and development (17) Selling, general and administrative (35) $ (191) Six Months Ended June 26, 2021 $ (248) Cost of revenues $ 384 Research and development 46 Selling, general and administrative 134 $ 564 Six Months Ended June 27, 2020 $ (126) Cost of revenues $ (258) Research and development (35) Selling, general and administrative (79) $ (372) Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis We measure and report our non-financial assets such as Property, plant and equipment, Goodwill and Intangible assets at fair value on a non-recurring basis if we determine these assets to be impaired or in the period when we make a business acquisition. Other than as discussed in Note 4, Acquisition

Warranty

Warranty	6 Months Ended
	Jun. 26, 2021
Product Warranties Disclosures [Abstract]
Warranty	Warranty We offer warranties on certain products and record a liability for the estimated future costs associated with warranty claims at the time revenue is recognized. The warranty liability is based upon historical experience and our estimate of the level of future costs. While we engage in product quality programs and processes, our warranty obligation is affected by product failure rates, material usage and service delivery costs. We continuously monitor product returns for warranty and maintain a reserve for the related expenses based upon our historical experience and any specifically identified failures. As we sell new products to our customers, we must exercise considerable judgment in estimating the expected failure rates. This estimating process is based on historical experience of similar products, as well as various other assumptions that we believe to be reasonable under the circumstances. We provide for the estimated cost of product warranties at the time revenue is recognized as a component of Cost of revenues in our Condensed Consolidated Statement of Income. Changes in our warranty liability were as follows (in thousands): Six Months Ended June 26, June 27, Balance at beginning of period $ 3,918 $ 1,942 Accruals 3,472 2,116 Settlements (3,132) (1,997) Balance at end of period $ 4,258 $ 2,061

Property, Plant, and Equipment,

Property, Plant, and Equipment, net	6 Months Ended
	Jun. 26, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment, net consisted of the following (in thousands): June 26, December 26, Land $ 4,751 $ 4,751 Machinery and equipment 239,322 226,185 Computer equipment and software 44,273 36,361 Furniture and fixtures 6,924 6,894 Leasehold improvements 81,421 79,144 Sub-total 376,691 353,335 Less: Accumulated depreciation and amortization (305,356) (294,468) Net, property, plant and equipment 71,335 58,867 Construction-in-process 54,013 45,236 Total $ 125,348 $ 104,103

Stockholders_ Equity and Stock-

Stockholders’ Equity and Stock-Based Compensation	6 Months Ended
	Jun. 26, 2021
Equity [Abstract]
Stockholders’ Equity and Stock-Based Compensation	Stockholders’ Equity and Stock-Based Compensation Common Stock Repurchase Program On October 26, 2020, our Board of Directors authorized a program to repurchase up to $50 million of outstanding common stock to offset potential dilution from issuances of common stock under our stock-based compensation plans. The share repurchase program will expire on October 28, 2022. During the six months ended June 26, 2021, we repurchased and retired 620,200 shares of common stock for $24.0 million and, as of June 26, 2021, $26.0 million remained available for future repurchases. Our policy related to repurchases of our common stock is to charge the excess of cost over par value to additional paid-in capital once the shares are retired. All repurchases were made in compliance with Rule 10b-18 under the Securities Exchange Act of 1934, as amended. Restricted Stock Units Restricted stock unit (“RSU”) activity under our equity incentive plan was as follows: Units Weighted Average Grant Date Fair Value RSUs at December 26, 2020 2,840,922 $ 19.80 Awards granted 43,949 36.71 Awards vested (451,957) 15.95 Awards forfeited (26,996) 22.66 RSUs at June 26, 2021 2,405,918 20.80 Performance Restricted Stock Units We may grant Performance RSUs (“PRSUs”) to certain executives, which vest based upon us achieving certain market performance criteria. There were no PRSUs granted during the six months ended June 26, 2021. PRSUs are included as part of the RSU activity above. Stock Options Stock option activity under our equity incentive plan was as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Aggregate Intrinsic Value Outstanding at December 26, 2020 106,000 $ 8.35 Options exercised (100,000) 8.44 Outstanding at June 26, 2021 6,000 $ 6.93 1.11 $ 172 Vested and expected to vest at June 26, 2021 6,000 $ 6.93 1.11 $ 172 Exercisable at June 26, 2021 6,000 $ 6.93 1.11 $ 172 Employee Stock Purchase Plan Information related to activity under our Employee Stock Purchase Plan (“ESPP”) was as follows: Six Months Ended June 26, 2021 Shares issued 228,784 Weighted average per share purchase price $ 22.14 Weighted average per share discount from the fair value of our common stock on the date of issuance $ (18.73) Stock-Based Compensation Stock-based compensation was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Cost of revenues $ 1,079 $ 901 $ 2,414 $ 1,838 Research and development 1,663 1,389 3,352 2,828 Selling, general and administrative 3,846 3,352 7,899 6,599 Total stock-based compensation $ 6,588 $ 5,642 $ 13,665 $ 11,265 Unrecognized Compensation Costs At June 26, 2021, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 23,767 1.87 Performance restricted stock units 6,369 1.77 Employee stock purchase plan 243 0.11 Total unrecognized stock-based compensation expense $ 30,379 1.83

Net Income per Share

Net Income per Share	6 Months Ended
	Jun. 26, 2021
Earnings Per Share [Abstract]
Net Income per Share	Net Income per Share The following table reconciles the shares used in calculating basic net income per share and diluted net income per share (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Weighted-average shares used in computing basic net income per share 77,463 76,275 77,530 76,140 Add potentially dilutive securities 2,003 2,586 2,091 2,570 Weighted-average shares used in computing diluted net income per share 79,466 78,861 79,621 78,710 Securities not included as they would have been antidilutive 128 — 118 13

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 26, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases See Note 13, Leases . Contractual Obligations and Commitments Our contractual obligations and commitments have not materially changed as of June 26, 2021 from those disclosed in our Annual Report on Form 10-K for the year ended December 26, 2020. Legal Matters

Leases

Leases	6 Months Ended
	Jun. 26, 2021
Leases [Abstract]
Leases	LeasesWe lease real estate space under non-cancelable operating lease agreements for commercial and industrial space, as well as for our corporate headquarters located in Livermore, California. Our leases have remaining terms of 1 to 8 years, and some leases include options to extend up to 20 years. We also have operating leases for automobiles with remaining lease terms of 1 to 4 years. We did not include any of our renewal options in our lease terms for calculating our lease liability as the renewal options allow us to maintain operational flexibility and we are not reasonably certain we will exercise these options at this time. The weighted-average remaining lease term for our operating leases was 6 years as of June 26, 2021 and the weighted-average discount rate was 3.70%. The components of lease expense were as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Lease expense: Operating lease expense $ 2,048 $ 1,794 $ 4,170 $ 3,719 Short-term lease expense 45 27 83 66 Variable lease expense 426 399 963 782 $ 2,519 $ 2,220 $ 5,216 $ 4,567 Future minimum payments under our non-cancelable operating leases were as follows as of June 26, 2021 (in thousands): Fiscal Year Amount Remainder of 2021 $ 4,264 2022 8,527 2023 7,172 2024 6,766 2025 6,742 Thereafter 14,850 Total minimum lease payments 48,321 Less: interest (6,202) Present value of net minimum lease payments 42,119 Less: current portion (7,908) Total long-term operating lease liabilities $ 34,211

Revenue

Revenue	6 Months Ended
	Jun. 26, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Transaction price allocated to the remaining performance obligations: On June 26, 2021, we had $10.7 million of remaining performance obligations, which were comprised of deferred service contracts and extended warranty contracts and contracts with overtime revenue recognition that are not yet delivered. We expect to recognize approximately 41.2% of our remaining performance obligations as revenue in the remainder of fiscal 2021, approximately 43.6% in fiscal 2022, and approximately 15.2% in fiscal 2023 and thereafter. The foregoing excludes the value of other remaining performance obligations as they have original durations of one year or less, and also excludes information about variable consideration allocated entirely to a wholly unsatisfied performance obligation. Contract balances: The timing of revenue recognition may differ from the timing of invoicing to customers. Accounts receivable is recorded at the invoiced amount, net of an allowance for doubtful accounts. A receivable is recognized in the period we deliver goods or provide services or when our right to consideration is unconditional. A contract asset is recorded when we have performed under the contract but our right to consideration is conditional on something other than the passage of time. Contract assets as of June 26, 2021 and December 26, 2020 were $3.6 million and $3.7 million, respectively, and are reported on the Condensed Consolidated Balance Sheets as a component of Prepaid expenses and other current assets. Contract liabilities include payments received in advance of performance under a contract and are satisfied as the associated revenue is recognized. Contract liabilities are reported on the Condensed Consolidated Balance Sheets at the end of each reporting period as a component of Deferred revenue and Other liabilities. Contract liabilities as of June 26, 2021 and December 26, 2020 were $23.9 million and $22.2 million, respectively. During the six months ended June 26, 2021, we recognized $12.8 million of revenue, that was included in contract liabilities as of December 26, 2020. Costs to obtain a contract: We generally expense sales commissions when incurred as a component of Selling, general and administrative expense, as the amortization period is typically less than one year. Revenue by Category: Refer to Note 15, Operating Segments and Enterprise-Wide Information

Operating Segments and Enterpri

Operating Segments and Enterprise-Wide Information	6 Months Ended
	Jun. 26, 2021
Segment Reporting [Abstract]
Operating Segments and Enterprise-Wide Information	Operating Segments and Enterprise-Wide Information Our chief operating decision maker (“CODM”) is our Chief Executive Officer, who reviews operating results to make decisions about allocating resources and assessing performance for the entire company. We operate in two reportable segments consisting of the Probe Cards segment and the Systems segment. The following table summarizes the operating results by reportable segment (dollars in thousands): Three Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 153,641 $ 34,435 $ — $ 188,076 $ 133,784 $ 24,040 $ — $ 157,824 Gross profit $ 66,600 $ 16,907 $ (7,224) $ 76,283 $ 61,523 $ 10,719 $ (6,075) $ 66,167 Gross margin 43.3 % 49.1 % 40.6 % 46.0 % 44.6 % 41.9 % Six Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 312,539 $ 62,173 $ — $ 374,712 $ 268,499 $ 50,078 $ — $ 318,577 Gross profit $ 136,915 $ 30,506 $ (14,432) $ 152,989 $ 122,266 $ 24,053 $ (12,762) $ 133,557 Gross margin 43.8 % 49.1 % 40.8 % 45.5 % 48.0 % 41.9 % Operating results provide useful information to our management for assessment of our performance and results of operations. Certain components of our operating results are utilized to determine executive compensation along with other measures. Corporate and Other includes unallocated expenses relating to amortization of intangible assets, inventory and fixed asset fair value adjustments due to acquisitions, share-based compensation, and other, which are not used in evaluating the results of, or in allocating resources to, our reportable segments. Certain revenue category information by reportable segment was as follows (in thousands): Three Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 103,726 $ — $ 103,726 $ 109,347 $ — $ 109,347 DRAM 42,088 — 42,088 19,052 — 19,052 Flash 7,827 — 7,827 5,385 — 5,385 Systems — 34,435 34,435 — 24,040 24,040 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Timing of revenue recognition: Products transferred at a point in time $ 153,129 $ 30,884 $ 184,013 $ 133,208 $ 22,548 $ 155,756 Products and services transferred over time 512 3,551 4,063 576 1,492 2,068 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Geographical region: Taiwan $ 46,737 $ 5,147 $ 51,884 $ 29,806 $ 3,365 $ 33,171 South Korea 35,426 751 36,177 14,249 864 15,113 United States 24,174 8,476 32,650 22,368 5,753 28,121 China 23,996 7,831 31,827 45,625 3,133 48,758 Asia-Pacific 1 12,569 1,719 14,288 4,347 2,153 6,500 Europe 6,466 5,544 12,010 8,767 5,365 14,132 Japan 3,477 4,227 7,704 6,679 3,380 10,059 Rest of the world 796 740 1,536 1,943 27 1,970 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Six Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 217,136 $ — $ 217,136 $ 215,092 $ — $ 215,092 DRAM 75,986 — 75,986 43,748 — 43,748 Flash 19,417 — 19,417 9,659 — 9,659 Systems — 62,173 62,173 — 50,078 50,078 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 Timing of revenue recognition: Products transferred at a point in time $ 311,605 $ 55,555 $ 367,160 $ 267,277 $ 47,406 $ 314,683 Products and services transferred over time 934 6,618 7,552 1,222 2,672 3,894 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 Geographical region: Taiwan $ 91,471 $ 5,993 $ 97,464 $ 60,245 $ 4,706 $ 64,951 China 61,827 12,625 74,452 82,905 9,495 92,400 United States 45,482 16,654 62,136 47,979 12,058 60,037 South Korea 53,427 1,835 55,262 27,941 1,260 29,201 Asia-Pacific 1 40,447 2,799 43,246 8,802 5,561 14,363 Europe 9,299 12,710 22,009 24,977 10,198 35,175 Japan 8,726 8,299 17,025 12,214 6,215 18,429 Rest of the world 1,860 1,258 3,118 3,436 585 4,021 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 1 Asia-Pacific includes all countries in the region except China, Japan, South Korea, and Taiwan, which are disclosed separately.

Basis of Presentation and New_2

Basis of Presentation and New Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 26, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying condensed consolidated financial information of FormFactor, Inc. is unaudited and has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). However, such information reflects all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 22, 2021. The results of operations for the interim periods presented are not necessarily indicative of the results to be expected for the full year.
Fiscal Year	Fiscal Year We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2021 and 2020 each contain 52 weeks and the six months ended June 26, 2021 and June 27, 2020 each contained 26 weeks. Fiscal 2021 will end on December 25, 2021.
New Accounting Pronouncements	New Accounting Pronouncements ASU 2019-12 In December 2019, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, “Income Taxes (Topic 740),” which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 on a prospective basis on December 27, 2020, the first day of fiscal 2021. The adoption did not have a material effect on our consolidated financial position, results of operations or cash flows. ASU 2020-04 In March 2020, the FASB issued ASU 2020-04, “Referenced Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU provides temporary optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform (Topic 848),” which permits entities to apply optional expedients in Topic 848 to derivative instruments modified because of discounting transition resulting from reference rate reform. ASU 2020-04 became effective upon issuance and may be applied prospectively to contract modifications made on or before December 31, 2022. ASU 2021-01 became effective upon issuance and may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or prospectively for contract modifications made on or before December 31, 2022. The Company has not yet applied the relief afforded by these standard amendments and is currently assessing contracts that will require modification due to reference rate reform to which these standard amendments may be applied.
Fair Value	Whenever possible, the fair values of our financial assets and liabilities are determined using quoted market prices of identical securities or quoted market prices of similar securities from active markets. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 valuations are obtained from real-time quotes for transactions in active exchange markets involving identical securities; • Level 2 valuations utilize significant observable inputs, such as quoted prices for similar assets or liabilities, quoted prices near the reporting date in markets that are less active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and • Level 3 valuations utilize unobservable inputs to the valuation methodology and include our own data about assumptions market participants would use in pricing the asset or liability based on the best information available under the circumstances. We did not have any transfers of assets or liabilities measured at fair value on a recurring basis to or from Level 1, Level 2 or Level 3 during the three and six months ended June 26, 2021 or the year ended December 26, 2020. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and term loans, net of unamortized issuance costs, approximate fair value due to their short maturities. No changes were made to our valuation techniques during the first six months of fiscal 2021.

Concentration of Credit and O_2

Concentration of Credit and Other Risks (Tables)	6 Months Ended
	Jun. 26, 2021
Risks and Uncertainties [Abstract]
Schedule of Customer Percentage of Revenue	Each of the following customers accounted for 10% or more of our revenues for the periods indicated: Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Intel Corporation 16.2 % 36.1 % 22.1 % 36.2 % Samsung Electronics., LTD. 14.7 % * * * Taiwan Semiconductor Manufacturing Co., LTD. 11.0 % * 11.2 % * 41.9 % 36.1 % 33.3 % 36.2 % *Represents less than 10% of total revenues.

Inventories, net (Tables)

Inventories, net (Tables)	6 Months Ended
	Jun. 26, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory Components	Inventories, net, consisted of the following (in thousands): June 26, December 26, Raw materials $ 56,138 $ 48,122 Work-in-progress 35,911 30,806 Finished goods 19,841 20,301 $ 111,890 $ 99,229

Acquisition (Tables)

Acquisition (Tables)	6 Months Ended
	Jun. 26, 2021
Business Combination and Asset Acquisition [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired, including goodwill and intangibles, and liabilities assumed is as follows (in thousands): Amount Cash and cash equivalents $ 1,680 Accounts receivable 1,017 Inventories 3,047 Property, plant and equipment 669 Operating lease, right of use assets 2,554 Prepaid expenses and other current assets 599 Tangible assets acquired 9,566 Deferred revenue (2,529) Accounts payable and accrued liabilities (1,268) Operating lease liabilities (2,554) Deferred tax liabilities (2,840) Total tangible assets acquired and liabilities assumed 375 Intangible assets 11,520 Goodwill 6,665 Net Assets Acquired $ 18,560 Amount Accounts receivable $ 4,365 Inventories 2,727 Property, plant and equipment 9,053 Operating lease, right of use assets 519 Prepaid expenses and other current assets 56 Tangible assets acquired 16,720 Accounts payable and accrued liabilities (743) Operating lease liabilities (519) Total tangible assets acquired and liabilities assumed 15,458 Intangible assets 13,600 Goodwill 5,942 Net assets acquired $ 35,000
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The intangible assets as of the closing date of the acquisition included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 7,500 10.0 Customer relationships 3,600 5.0 Order backlog 200 0.5 Trade names 220 5.0 Total intangible assets $ 11,520 8.2 The intangible assets as of July 30, 2020 included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 8,800 10.0 Customer relationships 4,400 3.0 In-process research and development 400 N/A Total intangible assets $ 13,600 7.7

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 26, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Reportable Segments	Goodwill by reportable segment was as follows (in thousands): Probe Cards Systems Total Goodwill, gross, as of December 28, 2019 $ 172,482 $ 26,714 $ 199,196 Addition - FRT GmbH Acquisition — 975 975 Addition - Baldwin Park Acquisition 5,590 — 5,590 Addition - HPD Acquisition — 4,654 4,654 Foreign currency translation — 2,346 2,346 Goodwill, gross, as of December 26, 2020 178,072 34,689 212,761 Addition - Baldwin Park Acquisition 352 — 352 Addition - HPD Acquisition — 2,011 2,011 Foreign currency translation — (576) (576) Goodwill, gross, as of July 26, 2021 $ 178,424 $ 36,124 $ 214,548
Schedule of Intangible Assets	Intangible assets were as follows (in thousands): June 26, 2021 December 26, 2020 Intangible Assets Gross Accumulated Net Gross Accumulated Net Developed technologies $ 173,627 $ 147,968 $ 25,659 $ 176,265 $ 137,754 $ 38,511 Customer relationships 51,641 36,437 15,204 52,488 33,378 19,110 Trade names 8,140 7,520 620 8,162 7,363 799 Order backlog 1,990 1,960 30 2,227 1,900 327 In-process research and development 400 — 400 400 — 400 $ 235,798 $ 193,885 $ 41,913 $ 239,542 $ 180,395 $ 59,147
Schedule of Amortization Expense	Amortization expense was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Cost of revenues $ 5,505 $ 4,926 $ 10,595 $ 10,676 Selling, general and administrative 1,590 1,528 3,305 3,041 $ 7,095 $ 6,454 $ 13,900 $ 13,717
Schedule of Estimated Amortization of Intangible Assets	The estimated future amortization of definite-lived intangible assets, excluding in-process research and development, is as follows (in thousands): Fiscal Year Amount Remainder of 2021 $ 4,885 2022 9,647 2023 7,271 2024 4,652 2025 4,389 Thereafter 10,669 $ 41,513

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 26, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): June 26, December 26, Accrued compensation and benefits $ 31,210 $ 33,110 Accrued income and other taxes 6,049 6,976 Accrued warranty 4,258 3,918 Employee stock purchase plan contributions withheld 4,768 4,240 Accrued contingent consideration — 4,012 Other accrued expenses 5,202 3,086 $ 51,487 $ 55,342

Fair Value and Derivative Ins_2

Fair Value and Derivative Instruments (Tables)	6 Months Ended
	Jun. 26, 2021
Fair Value Disclosures [Abstract]
Fair Value Assets Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis were as follows (in thousands): June 26, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 25,917 $ — $ — $ 25,917 Marketable securities: U.S. treasuries 27,112 — — 27,112 Certificates of deposit — 1,207 — 1,207 U.S. agency securities — 575 — 575 Corporate bonds — 28,893 — 28,893 Commercial paper — 38,175 — 38,175 27,112 68,850 — 95,962 Foreign exchange derivative contracts (Designated) — 152 — 152 Interest rate swap derivative contracts — 571 — 571 Total assets $ 53,029 $ 69,573 $ — $ 122,602 Liabilities: Foreign exchange derivative contracts (Designated) $ — $ (53) $ — $ (53) Interest rate swap derivative contracts — (103) — (103) Total liabilities $ — $ (156) $ — $ (156) December 26, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 43,019 $ — $ — $ 43,019 Marketable securities: U.S. treasuries 40,726 — — 40,726 Certificates of deposit — 2,179 — 2,179 U.S. agency securities — 575 — 575 Corporate bonds — 24,330 — 24,330 40,726 27,084 — 67,810 Foreign exchange derivative contracts — 1,057 — 1,057 Interest rate swap derivative contracts — 57 — 57 Total assets $ 83,745 $ 28,198 $ — $ 111,943 Liabilities: Interest rate swap derivative contracts $ — $ (87) $ — $ (87) Contingent consideration — — (4,012) (4,012) Total liabilities $ — $ (87) $ (4,012) $ (4,099)
Schedule of the Impact of Cash Flow Hedges on Consolidated Financial Statements	The impact of the interest rate swaps on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Three Months Ended June 26, 2021 $ (203) Interest expense $ (39) Interest expense $ — Three Months Ended June 27, 2020 $ (174) Interest expense $ (10) Interest expense $ — Six Months Ended June 26, 2021 $ 421 Interest expense $ (77) Interest expense $ — Six Months Ended June 27, 2020 $ (270) Interest expense $ 12 Interest expense $ —
Schedule of Foreign Currency Forward Contracts	The following table provides information about our foreign currency forward contracts outstanding as of June 26, 2021 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (12,678) $ (15,124) Japanese Yen Sell 1,802,229 16,251 Korean Won Buy (3,050,367) (2,703) Total USD notional amount of outstanding foreign exchange contracts $ (1,576) The impact of foreign exchange derivative contracts designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Three Months Ended June 26, 2021 $ 278 Cost of revenues $ 134 Research and development 16 Selling, general and administrative 52 $ 202 Three Months Ended June 27, 2020 $ 52 Cost of revenues $ (139) Research and development (17) Selling, general and administrative (35) $ (191) Six Months Ended June 26, 2021 $ (248) Cost of revenues $ 384 Research and development 46 Selling, general and administrative 134 $ 564 Six Months Ended June 27, 2020 $ (126) Cost of revenues $ (258) Research and development (35) Selling, general and administrative (79) $ (372)
Schedule of Gains and Losses Related to Non-designated Derivative Instruments	The impact of foreign exchange derivative contracts not designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized on Derivatives Three Months Ended Six Months Ended Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized on Derivatives June 26, June 27, June 26, June 27, Foreign exchange forward contracts Other expense, net $ (69) $ 234 $ 1,220 $ 349

Warranty (Tables)

Warranty (Tables)	6 Months Ended
	Jun. 26, 2021
Product Warranties Disclosures [Abstract]
Reconciliation of Changes in Warranty Liability	Changes in our warranty liability were as follows (in thousands): Six Months Ended June 26, June 27, Balance at beginning of period $ 3,918 $ 1,942 Accruals 3,472 2,116 Settlements (3,132) (1,997) Balance at end of period $ 4,258 $ 2,061

Property, Plant, and Equipmen_2

Property, Plant, and Equipment, net (Tables)	6 Months Ended
	Jun. 26, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment, net consisted of the following (in thousands): June 26, December 26, Land $ 4,751 $ 4,751 Machinery and equipment 239,322 226,185 Computer equipment and software 44,273 36,361 Furniture and fixtures 6,924 6,894 Leasehold improvements 81,421 79,144 Sub-total 376,691 353,335 Less: Accumulated depreciation and amortization (305,356) (294,468) Net, property, plant and equipment 71,335 58,867 Construction-in-process 54,013 45,236 Total $ 125,348 $ 104,103

Stockholders_ Equity and Stoc_2

Stockholders’ Equity and Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 26, 2021
Equity [Abstract]
Schedule of Restricted Stock Unit Activity	Restricted stock unit (“RSU”) activity under our equity incentive plan was as follows: Units Weighted Average Grant Date Fair Value RSUs at December 26, 2020 2,840,922 $ 19.80 Awards granted 43,949 36.71 Awards vested (451,957) 15.95 Awards forfeited (26,996) 22.66 RSUs at June 26, 2021 2,405,918 20.80
Schedule of Stock Option Activity	Stock option activity under our equity incentive plan was as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Aggregate Intrinsic Value Outstanding at December 26, 2020 106,000 $ 8.35 Options exercised (100,000) 8.44 Outstanding at June 26, 2021 6,000 $ 6.93 1.11 $ 172 Vested and expected to vest at June 26, 2021 6,000 $ 6.93 1.11 $ 172 Exercisable at June 26, 2021 6,000 $ 6.93 1.11 $ 172
Schedule of ESPP Activity	Information related to activity under our Employee Stock Purchase Plan (“ESPP”) was as follows: Six Months Ended June 26, 2021 Shares issued 228,784 Weighted average per share purchase price $ 22.14 Weighted average per share discount from the fair value of our common stock on the date of issuance $ (18.73)
Schedule of Stock-based Compensation	Stock-based compensation was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Cost of revenues $ 1,079 $ 901 $ 2,414 $ 1,838 Research and development 1,663 1,389 3,352 2,828 Selling, general and administrative 3,846 3,352 7,899 6,599 Total stock-based compensation $ 6,588 $ 5,642 $ 13,665 $ 11,265
Schedule of Unrecognized Stock-based Compensation	At June 26, 2021, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 23,767 1.87 Performance restricted stock units 6,369 1.77 Employee stock purchase plan 243 0.11 Total unrecognized stock-based compensation expense $ 30,379 1.83

Net Income per Share (Tables)

Net Income per Share (Tables)	6 Months Ended
	Jun. 26, 2021
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following table reconciles the shares used in calculating basic net income per share and diluted net income per share (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Weighted-average shares used in computing basic net income per share 77,463 76,275 77,530 76,140 Add potentially dilutive securities 2,003 2,586 2,091 2,570 Weighted-average shares used in computing diluted net income per share 79,466 78,861 79,621 78,710 Securities not included as they would have been antidilutive 128 — 118 13

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 26, 2021
Leases [Abstract]
Components of Lease Expense	The components of lease expense were as follows (in thousands): Three Months Ended Six Months Ended June 26, June 27, June 26, June 27, Lease expense: Operating lease expense $ 2,048 $ 1,794 $ 4,170 $ 3,719 Short-term lease expense 45 27 83 66 Variable lease expense 426 399 963 782 $ 2,519 $ 2,220 $ 5,216 $ 4,567
Schedule of Future Minimum Payments Under Leases	Future minimum payments under our non-cancelable operating leases were as follows as of June 26, 2021 (in thousands): Fiscal Year Amount Remainder of 2021 $ 4,264 2022 8,527 2023 7,172 2024 6,766 2025 6,742 Thereafter 14,850 Total minimum lease payments 48,321 Less: interest (6,202) Present value of net minimum lease payments 42,119 Less: current portion (7,908) Total long-term operating lease liabilities $ 34,211

Operating Segments and Enterp_2

Operating Segments and Enterprise-Wide Information (Tables)	6 Months Ended
	Jun. 26, 2021
Segment Reporting [Abstract]
Schedule of Operating Results by Segment	The following table summarizes the operating results by reportable segment (dollars in thousands): Three Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 153,641 $ 34,435 $ — $ 188,076 $ 133,784 $ 24,040 $ — $ 157,824 Gross profit $ 66,600 $ 16,907 $ (7,224) $ 76,283 $ 61,523 $ 10,719 $ (6,075) $ 66,167 Gross margin 43.3 % 49.1 % 40.6 % 46.0 % 44.6 % 41.9 % Six Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 312,539 $ 62,173 $ — $ 374,712 $ 268,499 $ 50,078 $ — $ 318,577 Gross profit $ 136,915 $ 30,506 $ (14,432) $ 152,989 $ 122,266 $ 24,053 $ (12,762) $ 133,557 Gross margin 43.8 % 49.1 % 40.8 % 45.5 % 48.0 % 41.9 %
Disaggregation of Revenue by Segment	Certain revenue category information by reportable segment was as follows (in thousands): Three Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 103,726 $ — $ 103,726 $ 109,347 $ — $ 109,347 DRAM 42,088 — 42,088 19,052 — 19,052 Flash 7,827 — 7,827 5,385 — 5,385 Systems — 34,435 34,435 — 24,040 24,040 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Timing of revenue recognition: Products transferred at a point in time $ 153,129 $ 30,884 $ 184,013 $ 133,208 $ 22,548 $ 155,756 Products and services transferred over time 512 3,551 4,063 576 1,492 2,068 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Geographical region: Taiwan $ 46,737 $ 5,147 $ 51,884 $ 29,806 $ 3,365 $ 33,171 South Korea 35,426 751 36,177 14,249 864 15,113 United States 24,174 8,476 32,650 22,368 5,753 28,121 China 23,996 7,831 31,827 45,625 3,133 48,758 Asia-Pacific 1 12,569 1,719 14,288 4,347 2,153 6,500 Europe 6,466 5,544 12,010 8,767 5,365 14,132 Japan 3,477 4,227 7,704 6,679 3,380 10,059 Rest of the world 796 740 1,536 1,943 27 1,970 Total $ 153,641 $ 34,435 $ 188,076 $ 133,784 $ 24,040 $ 157,824 Six Months Ended June 26, 2021 June 27, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 217,136 $ — $ 217,136 $ 215,092 $ — $ 215,092 DRAM 75,986 — 75,986 43,748 — 43,748 Flash 19,417 — 19,417 9,659 — 9,659 Systems — 62,173 62,173 — 50,078 50,078 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 Timing of revenue recognition: Products transferred at a point in time $ 311,605 $ 55,555 $ 367,160 $ 267,277 $ 47,406 $ 314,683 Products and services transferred over time 934 6,618 7,552 1,222 2,672 3,894 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 Geographical region: Taiwan $ 91,471 $ 5,993 $ 97,464 $ 60,245 $ 4,706 $ 64,951 China 61,827 12,625 74,452 82,905 9,495 92,400 United States 45,482 16,654 62,136 47,979 12,058 60,037 South Korea 53,427 1,835 55,262 27,941 1,260 29,201 Asia-Pacific 1 40,447 2,799 43,246 8,802 5,561 14,363 Europe 9,299 12,710 22,009 24,977 10,198 35,175 Japan 8,726 8,299 17,025 12,214 6,215 18,429 Rest of the world 1,860 1,258 3,118 3,436 585 4,021 Total $ 312,539 $ 62,173 $ 374,712 $ 268,499 $ 50,078 $ 318,577 1 Asia-Pacific includes all countries in the region except China, Japan, South Korea, and Taiwan, which are disclosed separately.

Concentration of Credit and O_3

Concentration of Credit and Other Risks (Details) - Customer Concentration Risk	3 Months Ended			6 Months Ended
	Jun. 26, 2021	Mar. 27, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Revenue from Contract with Customer Benchmark | Intel Corporation
Concentration Risk [Line Items]
Concentration risk percentage	16.20%		36.10%	22.10%	36.20%
Revenue from Contract with Customer Benchmark | Samsung Electronics., LTD.
Concentration Risk [Line Items]
Concentration risk percentage	14.70%
Revenue from Contract with Customer Benchmark | Taiwan Semiconductor Manufacturing Co., LTD.
Concentration Risk [Line Items]
Concentration risk percentage	11.00%			11.20%
Revenue from Contract with Customer Benchmark | Customers Representing 10% or More of Total Revenues
Concentration Risk [Line Items]
Concentration risk percentage	41.90%		36.10%	33.30%	36.20%
Accounts Receivable | Major Customer 1
Concentration Risk [Line Items]
Concentration risk percentage		15.30%		20.60%
Accounts Receivable | Major Customer 2
Concentration Risk [Line Items]
Concentration risk percentage		13.70%

Inventories, net (Details)

Inventories, net (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 56,138	$ 48,122
Work-in-progress	35,911	30,806
Finished goods	19,841	20,301
Inventories	$ 111,890	$ 99,229

Acquisition - Additional Inform

Acquisition - Additional Information (Details) $ in Thousands	Oct. 19, 2020USD ($)millikelvin	Jul. 30, 2020USD ($)
High Precision Devices, Inc.
Business Acquisition [Line Items]
Business acquisition, percentage acquired	100.00%
Consideration transferred	$ 16,900
Cash and cash equivalents	$ 1,680
High Precision Devices, Inc. | Minimum
Business Acquisition [Line Items]
Sensor markets, operating temperature | millikelvin	30
Baldwin Park
Business Acquisition [Line Items]
Consideration transferred		$ 35,000

Acquisition - Assets Acquired a

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020	Oct. 19, 2020	Jul. 30, 2020	Dec. 28, 2019
Business Acquisition [Line Items]
Goodwill	$ 214,548	$ 212,761			$ 199,196
High Precision Devices, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,680
Accounts receivable			1,017
Inventories			3,047
Property, plant and equipment			669
Operating lease, right of use assets			2,554
Prepaid expenses and other current assets			599
Tangible assets acquired			9,566
Deferred revenue			(2,529)
Accounts payable and accrued liabilities			(1,268)
Operating lease liabilities			(2,554)
Deferred tax liabilities			(2,840)
Total tangible assets acquired and liabilities assumed			375
Intangible assets			11,520
Goodwill			6,665
Net Assets Acquired			$ 18,560
Baldwin Park
Business Acquisition [Line Items]
Accounts receivable				$ 4,365
Inventories				2,727
Property, plant and equipment				9,053
Operating lease, right of use assets				519
Prepaid expenses and other current assets				56
Tangible assets acquired				16,720
Accounts payable and accrued liabilities				(743)
Operating lease liabilities				(519)
Total tangible assets acquired and liabilities assumed				15,458
Intangible assets				13,600
Goodwill				5,942
Net Assets Acquired				$ 35,000

Acquisition - Intangible Assets

Acquisition - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Oct. 19, 2020	Jul. 30, 2020
High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 11,520
Weighted Average Useful Life (in years)	8 years 2 months 12 days
Baldwin Park
Business Acquisition [Line Items]
Amount		$ 13,600
Weighted Average Useful Life (in years)		7 years 8 months 12 days
Baldwin Park | In-process research and development
Business Acquisition [Line Items]
Amount		$ 400
Developed technologies | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 7,500
Weighted Average Useful Life (in years)	10 years
Developed technologies | Baldwin Park
Business Acquisition [Line Items]
Amount		$ 8,800
Weighted Average Useful Life (in years)		10 years
Customer relationships | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 3,600
Weighted Average Useful Life (in years)	5 years
Customer relationships | Baldwin Park
Business Acquisition [Line Items]
Amount		$ 4,400
Weighted Average Useful Life (in years)		3 years
Order backlog | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 200
Weighted Average Useful Life (in years)	6 months
Trade names | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 220
Weighted Average Useful Life (in years)	5 years

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 26, 2021	Dec. 26, 2020
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 212,761	$ 199,196
Foreign currency translation	(576)	2,346
Goodwill, ending balance	214,548	212,761
FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		975
Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period	352	5,590
High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	2,011	4,654
Probe Cards
Goodwill [Roll Forward]
Goodwill, beginning balance	178,072	172,482
Foreign currency translation	0	0
Goodwill, ending balance	178,424	178,072
Probe Cards | FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		0
Probe Cards | Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period	352	5,590
Probe Cards | High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	0	0
Systems
Goodwill [Roll Forward]
Goodwill, beginning balance	34,689	26,714
Foreign currency translation	(576)	2,346
Goodwill, ending balance	36,124	34,689
Systems | FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		975
Systems | Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period	0	0
Systems | High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	$ 2,011	$ 4,654

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Additional information (Details)	3 Months Ended
	Jun. 26, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, impairment loss	$ 0

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Finite-Lived Intangible Assets [Line Items]
Gross	$ 235,798	$ 239,542
Accumulated Amortization	193,885	180,395
Net	41,913	59,147
Developed technologies
Finite-Lived Intangible Assets [Line Items]
Gross	173,627	176,265
Accumulated Amortization	147,968	137,754
Net	25,659	38,511
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross	8,140	8,162
Accumulated Amortization	7,520	7,363
Net	620	799
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	51,641	52,488
Accumulated Amortization	36,437	33,378
Net	15,204	19,110
Order backlog
Finite-Lived Intangible Assets [Line Items]
Gross	1,990	2,227
Accumulated Amortization	1,960	1,900
Net	30	327
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Gross	400	400
Accumulated Amortization	0	0
Net	$ 400	$ 400

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 7,095	$ 6,454	$ 13,900	$ 13,717
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
Remainder of 2021	4,885		4,885
2022	9,647		9,647
2023	7,271		7,271
2024	4,652		4,652
2025	4,389		4,389
Thereafter	10,669		10,669
Net	41,513		41,513
Cost of revenues
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	5,505	4,926	10,595	10,676
Selling, general and administrative
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 1,590	$ 1,528	$ 3,305	$ 3,041

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 31,210	$ 33,110
Accrued income and other taxes	6,049	6,976
Accrued warranty	4,258	3,918
Employee stock purchase plan contributions withheld	4,768	4,240
Accrued contingent consideration	0	4,012
Other accrued expenses	5,202	3,086
Accrued liabilities	$ 51,487	$ 55,342

Fair Value and Derivative Ins_3

Fair Value and Derivative Instruments - Fair Value Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 95,962	$ 67,810
Total assets	122,602	111,943
Contingent consideration		(4,012)
Total liabilities	(156)	(4,099)
Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(53)
Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	152	1,057
Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	571	57
Derivative liability	(103)	(87)
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	25,917	43,019
U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	27,112	40,726
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	1,207	2,179
U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	575	575
Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	28,893	24,330
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	38,175
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	27,112	40,726
Total assets	53,029	83,745
Contingent consideration		0
Total liabilities	0	0
Level 1 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0
Level 1 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Level 1 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Derivative liability	0	0
Level 1 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	25,917	43,019
Level 1 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	27,112	40,726
Level 1 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 1 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 1 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 1 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	68,850	27,084
Total assets	69,573	28,198
Contingent consideration		0
Total liabilities	(156)	(87)
Level 2 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(53)
Level 2 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	152	1,057
Level 2 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	571	57
Derivative liability	(103)	(87)
Level 2 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Level 2 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 2 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	1,207	2,179
Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	575	575
Level 2 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	28,893	24,330
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	38,175
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Total assets	0	0
Contingent consideration		(4,012)
Total liabilities	0	(4,012)
Level 3 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0
Level 3 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Level 3 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Derivative liability	0	0
Level 3 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Level 3 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	$ 0
Level 3 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 0

Fair Value and Derivative Ins_4

Fair Value and Derivative Instruments - Additional Information (Details) $ in Thousands, € in Millions	Oct. 09, 2019EUR (€)	Jun. 26, 2021USD ($)	Jun. 26, 2021USD ($)	Jun. 27, 2020USD ($)	Dec. 26, 2020USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration					$ 4,012
Payment for contingent consideration liability		$ 3,900
Gain on contingent consideration			$ (95)	$ (3,700)
Selling, general and administrative
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gain on contingent consideration		$ 100
FRT
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration, calculation amount, multiple of EBIT	150.00%
FRT | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration | €	€ 10.3

Fair Value and Derivative Ins_5

Fair Value and Derivative Instruments - Impact of Cash Flow Hedges and Derivatives (Details) - Designated as hedging instrument - Interest rate contracts - Cash flow hedging - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	$ (203)	$ (174)	$ 421	$ (270)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (39)	$ (10)	$ (77)	$ 12

Fair Value and Derivative Ins_6

Fair Value and Derivative Instruments - Foreign Currency Forward Contracts (Details) - Jun. 26, 2021 - Foreign exchange forward contracts € in Thousands, ₩ in Thousands, ¥ in Thousands, $ in Thousands	EUR (€)	USD ($)	JPY (¥)	KRW (₩)
Derivative [Line Items]
Derivative, notional amount		$ 1,576
Buy | Euro Dollar
Derivative [Line Items]
Derivative, notional amount	€ 12,678	15,124
Buy | Korean Won
Derivative [Line Items]
Derivative, notional amount		2,703		₩ 3,050,367
Sell | Japanese Yen
Derivative [Line Items]
Derivative, notional amount		$ 16,251	¥ 1,802,229

Fair Value and Derivative Ins_7

Fair Value and Derivative Instruments - Gains and Losses Related to Non-designated Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Derivatives Not Designated as Hedging Instruments | Foreign exchange forward contracts | Location of Gain (Loss) Recognized on Derivatives
Derivatives, Fair Value [Line Items]
Derivatives Not Designated as Hedging Instruments	$ (69)	$ 234	$ 1,220	$ 349

Fair Value and Derivative Ins_8

Fair Value and Derivative Instruments - Impact of Foreign Exchange Derivative Contracts Designated as Cash Flow Hedges (Details) - Foreign exchange forward contracts - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative	$ 278	$ 52	$ (248)	$ (126)
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	202	(191)	564	(372)
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	134	(139)	384	(258)
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	16	(17)	46	(35)
Selling, general and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	$ 52	$ (35)	$ 134	$ (79)

Fair Value and Derivative Ins_9

Fair Value and Derivative Instruments - Assets Measured at Fair Value on a Non-Recurring Basis (Details) - USD ($)	Jun. 26, 2021	Dec. 26, 2020	Jun. 27, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on non-recurring basis	$ 122,602,000	$ 111,943,000
Liabilities measured at fair value on non-recurring basis	156,000	$ 4,099,000
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on non-recurring basis	0		$ 0
Liabilities measured at fair value on non-recurring basis	$ 0		$ 0

Warranty (Details)

Warranty (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 3,918	$ 1,942
Accruals	3,472	2,116
Settlements	(3,132)	(1,997)
Balance at end of period	$ 4,258	$ 2,061

Property, Plant, and Equipmen_3

Property, Plant, and Equipment, net (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Property, Plant and Equipment [Line Items]
Sub-total	$ 376,691	$ 353,335
Less: Accumulated depreciation and amortization	(305,356)	(294,468)
Net, property, plant and equipment	71,335	58,867
Construction-in-process	54,013	45,236
Total	125,348	104,103
Land
Property, Plant and Equipment [Line Items]
Sub-total	4,751	4,751
Machinery and equipment
Property, Plant and Equipment [Line Items]
Sub-total	239,322	226,185
Computer equipment and software
Property, Plant and Equipment [Line Items]
Sub-total	44,273	36,361
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Sub-total	6,924	6,894
Leasehold improvements
Property, Plant and Equipment [Line Items]
Sub-total	$ 81,421	$ 79,144

Stockholders_ Equity and Stoc_3

Stockholders’ Equity and Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 26, 2021	Jun. 26, 2021	Oct. 26, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase of common stock value retired through repurchase program	$ 18,213,000	$ 23,951,000
PRSUs | Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		0
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program authorized amount			$ 50,000,000
Purchase of common stock retired through repurchase program (in shares)		620,200
Purchase of common stock value retired through repurchase program		$ 24,000,000
Amount remaining for future repurchases	$ 26,000,000	$ 26,000,000

Stockholders_ Equity and Stoc_4

Stockholders’ Equity and Stock-Based Compensation - Restricted Stock Unit Activity (Details) - Equity Incentive Plan - Restricted Stock Units	6 Months Ended
	Jun. 26, 2021$ / sharesshares
Units
Beginning balance (in shares) | shares	2,840,922
Awards granted (in shares) | shares	43,949
Awards vested (in shares) | shares	(451,957)
Awards canceled (in shares) | shares	(26,996)
Ending balance (in shares) | shares	2,405,918
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 19.80
Awards granted (in dollars per share) | $ / shares	36.71
Awards vested (in dollars per share) | $ / shares	15.95
Awards canceled (in dollars per share) | $ / shares	22.66
Ending balance (in dollars per share) | $ / shares	$ 20.80

Stockholders_ Equity and Stoc_5

Stockholders’ Equity and Stock-Based Compensation - Stock Option Activity (Details) - Equity Incentive Plan $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 26, 2021USD ($)$ / sharesshares
Options Outstanding
Outstanding, beginning of period (in shares) | shares	106
Options exercised (in shares) | shares	(100)
Outstanding, end of period (in shares) | shares	6
Vested and expected to vest (in shares) | shares	6
Exercisable (in shares) | shares	6
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 8.35
Options exercised (in dollars per share) | $ / shares	8.44
Outstanding, end of period (in dollars per share) | $ / shares	6.93
Vested and expected to vest (in dollars per share) | $ / shares	6.93
Exercisable (in dollars per share) | $ / shares	$ 6.93
Additional Disclosures
Outstanding, weighted average remaining contractual life	1 year 1 month 9 days
Vested and expected to vest, weighted average remaining contractual life	1 year 1 month 9 days
Exercisable, weighted average remaining contractual life	1 year 1 month 9 days
Outstanding, aggregate intrinsic value | $	$ 172
Vested end expected to vest, aggregate intrinsic value | $	172
Exercisable, aggregate intrinsic value | $	$ 172

Stockholders_ Equity and Stoc_6

Stockholders’ Equity and Stock-Based Compensation - ESPP Activity (Details) - Employee stock purchase plan	6 Months Ended
	Jun. 26, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares) | shares	228,784
Weighted average per share purchase price (in dollars per share)	$ 22.14
Weighted average per share discount from the fair value of our common stock on the date of issuance (in dollars per share)	$ (18.73)

Stockholders_ Equity and Stoc_7

Stockholders’ Equity and Stock-Based Compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 6,588	$ 5,642	$ 13,665	$ 11,265
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,079	901	2,414	1,838
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,663	1,389	3,352	2,828
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 3,846	$ 3,352	$ 7,899	$ 6,599

Stockholders_ Equity and Stoc_8

Stockholders’ Equity and Stock-Based Compensation - Unrecognized Compensation Costs (Details) $ in Thousands	6 Months Ended
	Jun. 26, 2021USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 30,379
Average Expected Recognition Period in Years	1 year 9 months 29 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 23,767
Average Expected Recognition Period in Years	1 year 10 months 13 days
Performance restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 6,369
Average Expected Recognition Period in Years	1 year 9 months 7 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 243
Average Expected Recognition Period in Years	1 month 9 days

Net Income per Share (Details)

Net Income per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Earnings Per Share [Abstract]
Weighted-average shares used in computing basic net income per share (in shares)	77,463	76,275	77,530	76,140
Add potentially dilutive securities (in shares)	2,003	2,586	2,091	2,570
Weighted-average shares used in computing diluted net income per share (in shares)	79,466	78,861	79,621	78,710
Securities not included as they would have been antidilutive (in shares)	128	0	118	13

Leases - Narrative (Details)

Leases - Narrative (Details)	Jun. 26, 2021
Lessee, Lease, Description [Line Items]
Operating lease, renewal term	20 years
Operating lease, weighted average remaining lease term	6 years
Operating lease, weighted average discount rate	3.70%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	8 years
Automobiles | Minimum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	1 year
Automobiles | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	4 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Leases [Abstract]
Operating lease expense	$ 2,048	$ 1,794	$ 4,170	$ 3,719
Short-term lease expense	45	27	83	66
Variable lease expense	426	399	963	782
Total lease expense	$ 2,519	$ 2,220	$ 5,216	$ 4,567

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Payments Under Leases (Details) - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Leases [Abstract]
Remainder of 2021	$ 4,264
2022	8,527
2023	7,172
2024	6,766
2025	6,742
Thereafter	14,850
Total minimum lease payments	48,321
Less: interest	(6,202)
Present value of net minimum lease payments	42,119
Less: current portion	(7,908)	$ (6,704)
Long-term operating lease liabilities	$ 34,211	$ 27,996

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 26, 2021	Dec. 26, 2020
Revenue from Contract with Customer [Abstract]
Performance obligations	$ 10.7
Contract assets	3.6	$ 3.7
Contract liabilities	23.9	$ 22.2
Revenue recognized included in contracts	$ 12.8

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details)	Jun. 26, 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-06-27
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	41.20%
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	43.60%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	15.20%
Revenue, remaining performance obligation, expected timing of satisfaction, period

Operating Segments and Enterp_3

Operating Segments and Enterprise-Wide Information - Additional Information (Details)	6 Months Ended
	Jun. 26, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	2

Operating Segments and Enterp_4

Operating Segments and Enterprise-Wide Information - Operating Results by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Segment Reporting Information [Line Items]
Revenues	$ 188,076	$ 157,824	$ 374,712	$ 318,577
Gross profit	$ 76,283	$ 66,167	$ 152,989	$ 133,557
Gross margin	40.60%	41.90%	40.80%	41.90%
Probe Cards
Segment Reporting Information [Line Items]
Revenues	$ 153,641	$ 133,784	$ 312,539	$ 268,499
Systems
Segment Reporting Information [Line Items]
Revenues	34,435	24,040	62,173	50,078
Corporate and Other
Segment Reporting Information [Line Items]
Revenues			0	0
Gross profit			$ (14,432)	$ (12,762)
Gross margin
Operating segments | Probe Cards
Segment Reporting Information [Line Items]
Revenues	153,641	133,784	$ 312,539	$ 268,499
Gross profit	$ 66,600	$ 61,523	$ 136,915	$ 122,266
Gross margin	43.30%	46.00%	43.80%	45.50%
Operating segments | Systems
Segment Reporting Information [Line Items]
Revenues	$ 34,435	$ 24,040	$ 62,173	$ 50,078
Gross profit	$ 16,907	$ 10,719	$ 30,506	$ 24,053
Gross margin	49.10%	44.60%	49.10%	48.00%
Operating segments | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0
Gross profit	$ (7,224)	$ (6,075)
Gross margin

Operating Segments and Enterp_5

Operating Segments and Enterprise-Wide Information - Revenue by Segment, Recognition Type, and Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 188,076	$ 157,824	$ 374,712	$ 318,577
Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	153,641	133,784	312,539	268,499
Systems
Disaggregation of Revenue [Line Items]
Revenues	34,435	24,040	62,173	50,078
Taiwan
Disaggregation of Revenue [Line Items]
Revenues	51,884	33,171	55,262	29,201
Taiwan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	46,737	29,806	53,427	27,941
Taiwan | Systems
Disaggregation of Revenue [Line Items]
Revenues	5,147	3,365	1,835	1,260
South Korea
Disaggregation of Revenue [Line Items]
Revenues	36,177	15,113	97,464	64,951
South Korea | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	35,426	14,249	91,471	60,245
South Korea | Systems
Disaggregation of Revenue [Line Items]
Revenues	751	864	5,993	4,706
United States
Disaggregation of Revenue [Line Items]
Revenues	32,650	28,121	62,136	60,037
United States | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	24,174	22,368	45,482	47,979
United States | Systems
Disaggregation of Revenue [Line Items]
Revenues	8,476	5,753	16,654	12,058
China
Disaggregation of Revenue [Line Items]
Revenues	31,827	48,758	74,452	92,400
China | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	23,996	45,625	61,827	82,905
China | Systems
Disaggregation of Revenue [Line Items]
Revenues	7,831	3,133	12,625	9,495
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	14,288	6,500	17,025	18,429
Asia-Pacific | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	12,569	4,347	8,726	12,214
Asia-Pacific | Systems
Disaggregation of Revenue [Line Items]
Revenues	1,719	2,153	8,299	6,215
Europe
Disaggregation of Revenue [Line Items]
Revenues	12,010	14,132	22,009	35,175
Europe | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	6,466	8,767	9,299	24,977
Europe | Systems
Disaggregation of Revenue [Line Items]
Revenues	5,544	5,365	12,710	10,198
Japan
Disaggregation of Revenue [Line Items]
Revenues	7,704	10,059	43,246	14,363
Japan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	3,477	6,679	40,447	8,802
Japan | Systems
Disaggregation of Revenue [Line Items]
Revenues	4,227	3,380	2,799	5,561
Rest of the world
Disaggregation of Revenue [Line Items]
Revenues	1,536	1,970	3,118	4,021
Rest of the world | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	796	1,943	1,860	3,436
Rest of the world | Systems
Disaggregation of Revenue [Line Items]
Revenues	740	27	1,258	585
Products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues	184,013	155,756	367,160	314,683
Products transferred at a point in time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	153,129	133,208	311,605	267,277
Products transferred at a point in time | Systems
Disaggregation of Revenue [Line Items]
Revenues	30,884	22,548	55,555	47,406
Products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenues	4,063	2,068	7,552	3,894
Products and services transferred over time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	512	576	934	1,222
Products and services transferred over time | Systems
Disaggregation of Revenue [Line Items]
Revenues	3,551	1,492	6,618	2,672
Foundry & Logic
Disaggregation of Revenue [Line Items]
Revenues	103,726	109,347	217,136	215,092
Foundry & Logic | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	103,726	109,347	217,136	215,092
Foundry & Logic | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
DRAM
Disaggregation of Revenue [Line Items]
Revenues	42,088	19,052	75,986	43,748
DRAM | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	42,088	19,052	75,986	43,748
DRAM | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Flash
Disaggregation of Revenue [Line Items]
Revenues	7,827	5,385	19,417	9,659
Flash | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	7,827	5,385	19,417	9,659
Flash | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Systems
Disaggregation of Revenue [Line Items]
Revenues	34,435	24,040	62,173	50,078
Systems | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Systems | Systems
Disaggregation of Revenue [Line Items]
Revenues	$ 34,435	$ 24,040	$ 62,173	$ 50,078