FormFactor (FORM) 10-Q 4 Aug 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 27, 2020	Jul. 31, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 27, 2020
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		77,058,712
Amendment Flag	false
Entity Central Index Key	0001039399
Current Fiscal Year End Date	--12-26
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 27, 2020USD ($)	Jun. 27, 2020USD ($)	Dec. 28, 2019USD ($)
Current assets:
Cash and cash equivalents	$ 199,926	$ 199,926	$ 144,545
Marketable securities	61,177	61,177	76,327
Accounts receivable, net of allowance for doubtful accounts of $226 and $222	86,616	86,616	97,868
Inventories, net	87,813	87,813	83,258
Restricted cash	1,424	1,424	1,981
Prepaid expenses and other current assets	18,458	18,458	15,064
Total current assets	455,414	455,414	419,043
Restricted cash	1,375	1,375	1,411
Operating Lease, Right-of-Use Asset	29,027	29,027	31,420
Property, plant and equipment, net of accumulated depreciation	83,662	83,662	58,747
Goodwill	200,293	200,293	199,196
Intangibles, net	43,785	43,785	57,610
Deferred tax assets	69,712	69,712	71,252
Other assets	966	966	1,203
Total assets	884,234	884,234	839,882
Current liabilities:
Accounts payable	44,334	44,334	40,914
Accrued liabilities	37,620	37,620	36,439
Current portion of term loans, net of unamortized issuance costs	21,325	21,325	42,846
Deferred revenue	13,789	13,789	9,810
Operating Lease, Liability, Current	6,168	6,168	6,551
Total current liabilities	123,236	123,236	136,560
Term loans, less current portion, net of unamortized issuance costs	28,725	28,725	15,639
Deferred tax liabilities	6,343	6,343	6,986
Long-term operating lease liabilities	26,816	26,816	29,088
Other liabilities	8,392	8,392	10,612
Total liabilities	193,512	193,512	198,885
Stockholders’ equity:
Common stock, $0.001 par value:	77	77	76
Additional paid-in capital	898,069	898,069	885,821
Accumulated other comprehensive loss	458	458	(659)
Accumulated deficit	(207,882)	(207,882)	(244,241)
Total stockholders’ equity	690,722	690,722	640,997
Total liabilities and stockholders’ equity	884,234	884,234	839,882
Marketable securities	61,177	61,177	$ 76,327
Gross profit	66,167	133,557
Corporate and Other
Gross profit	$ (6,075)	$ (12,762)

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Statement of Financial Position [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 226	$ 222
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 281,539	$ 273,001
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)	76,501,459	75,764,990
Common stock, shares outstanding (In shares)	75,764,990	75,764,990

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Income Statement [Abstract]
Revenues	$ 157,824	$ 138,018	$ 318,577	$ 270,231
Cost of revenues	91,657	82,666	185,020	162,358
Gross profit	66,167	55,352	133,557	107,873
Operating expenses:
Research and development	20,919	20,074	42,186	39,797
Selling, general and administrative	22,755	26,283	50,448	51,467
Total operating expenses	43,674	46,357	92,634	91,264
Operating income	22,493	8,995	40,923	16,609
Interest income	376	684	1,061	1,264
Interest expense	(171)	(522)	(489)	(1,117)
Other income (expense), net	(67)	81	(158)	(3)
Income before income taxes	22,631	9,238	41,337	16,753
Provision for income taxes	2,162	2,290	4,978	4,322
Net income	$ 20,469	$ 6,948	$ 36,359	$ 12,431
Net income per share:
Basic (In dollars per share)	$ 0.27	$ 0.09	$ 0.48	$ 0.17
Diluted (In dollars per share)	$ 0.26	$ 0.09	$ 0.46	$ 0.16
Basic
Basic (In shares)	76,275	74,478	76,140	74,483
Diluted (In shares)	78,861	76,189	78,710	76,061

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 20,469	$ 6,948	$ 36,359	$ 12,431
Other comprehensive income (loss), net of tax:
Translation adjustments and other	763	689	364	(228)
Unrealized gains on available-for-sale marketable securities	524	142	497	293
Other comprehensive income (loss), net of tax	1,367	758	1,117	(621)
Comprehensive income	21,836	7,706	37,476	11,810
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	$ 80	$ (73)	$ 256	$ (686)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (In shares) at Dec. 29, 2018		74,139,712,000
Beginning balance at Dec. 29, 2018	$ 580,164	$ 74	$ 862,897	$ 780	$ (283,587)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (In shares)		301,497,000
Issuance of common stock under the Employee Stock Purchase Plan	3,670		3,670
Issuance of common stock pursuant to exercise of options for cash (In shares)		19,207,000
Issuance of common stock pursuant to exercise of options	90		90
Issuance of common stock pursuant to vesting of restricted stock units (In shares)		231,365,000
Issuance of common stock pursuant to exercise of options	(2,156)	$ 1	(2,157)
Stock-based compensation	10,524		10,524
Other comprehensive loss	(621)			(621)
Net income	12,431				12,431
Ending balance (In shares) at Jun. 29, 2019		74,691,781,000
Ending balance at Jun. 29, 2019	604,102	$ 75	875,024	159	(271,156)
Beginning balance (In shares) at Mar. 30, 2019		74,488,498,000
Beginning balance at Mar. 30, 2019	592,988	$ 74	871,617	(599)	(278,104)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to vesting of restricted stock units (In shares)		203,283,000
Issuance of common stock pursuant to exercise of options	(1,854)		(1,855)
Stock-based compensation	5,262		5,262
Other comprehensive loss	758			758
Net income	6,948				6,948
Ending balance (In shares) at Jun. 29, 2019		74,691,781,000
Ending balance at Jun. 29, 2019	$ 604,102	$ 75	875,024	159	(271,156)
Beginning balance (In shares) at Dec. 28, 2019	75,764,990	75,764,990,000
Beginning balance at Dec. 28, 2019	$ 640,997	$ 76	885,821	(659)	(244,241)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (In shares)		311,591,000
Issuance of common stock under the Employee Stock Purchase Plan	4,066		4,066
Issuance of common stock pursuant to exercise of options for cash (In shares)		105,769,000
Issuance of common stock pursuant to exercise of options	869	$ 1	868
Issuance of common stock pursuant to vesting of restricted stock units (In shares)		319,109,000
Issuance of common stock pursuant to exercise of options	(3,800)		(3,800)
Stock-based compensation	11,114		11,114
Other comprehensive loss	1,117			1,117
Net income	$ 36,359				36,359
Ending balance (In shares) at Jun. 27, 2020	75,764,990	76,501,459,000
Ending balance at Jun. 27, 2020	$ 690,722	$ 77	898,069	458	(207,882)
Beginning balance (In shares) at Mar. 28, 2020		76,158,251,000
Beginning balance at Mar. 28, 2020	666,417	$ 77	895,600	(909)	(228,351)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options for cash (In shares)		293,208,000
Issuance of common stock pursuant to exercise of options	(3,415)		(3,415)
Issuance of common stock pursuant to vesting of restricted stock units (In shares)		50,000,000
Issuance of common stock pursuant to exercise of options	422		422
Stock-based compensation	5,462		5,462
Other comprehensive loss	1,367			1,367
Net income	$ 20,469				20,469
Ending balance (In shares) at Jun. 27, 2020	75,764,990	76,501,459,000
Ending balance at Jun. 27, 2020	$ 690,722	$ 77	$ 898,069	$ 458	$ (207,882)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019
Cash flows from operating activities:
Net income	$ 36,359	$ 12,431
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,240	8,289
Amortization	13,717	14,169
Reduction in the carrying amount of right-of-use assets	2,419	2,620
Stock-based compensation expense	11,265	10,584
Provision for excess and obsolete inventories	6,407	5,304
Gain on contingent consideration	(3,700)	0
Other adjustments to reconcile net income to net cash provided by operating activities	1,327	(173)
Changes in assets and liabilities:
Accounts receivable	11,364	24,177
Inventories	(11,089)	(11,574)
Prepaid expenses and other current assets	3,271	(1,838)
Other assets	248	(572)
Accounts payable	5,247	(11,115)
Accrued liabilities	1,529	(309)
Other liabilities	292	(93)
Deferred revenues	3,855	2,216
Operating lease liabilities	(2,762)	(2,416)
Net cash provided by operating activities	82,447	55,376
Cash flows from investing activities:
Acquisition of property, plant and equipment	(36,743)	(11,460)
Proceeds from sale of a subsidiary	82	56
Purchases of marketable securities	35,410	19,710
Net cash used in investing activities	(20,977)	(12,470)
Net cash used in investing activities
Payments to Acquire Marketable Securities	19,726	20,776
Cash flows from financing activities:
Proceeds from issuances of common stock	4,935	3,870
Tax withholdings related to net share settlements of equity awards	(3,800)	(2,157)
Proceeds from term loan debt	18,000	0
Principal repayments on term loans	(26,322)	(18,750)
Payment of term loan debt issuance costs	(78)	0
Net cash used in financing activities	(7,265)	(17,037)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	583	279
Effect of exchange rate changes on cash, cash equivalents and restricted cash	54,788	26,148
Net increase in cash, cash equivalents and restricted cash	147,937	100,546
Cash, cash equivalents and restricted cash, beginning of period	202,725	126,694
Fair value of stock options and restricted stock-based awards assumed in connection with acquisition of Cascade Microtech
Change in accounts payable and accrued liabilities related to property, plant and equipment purchases	2,274	(2,497)
Operating lease, right-of-use assets obtained in exchange for lease obligations	428	35,885
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	4,133	1,700
Cash paid for interest	$ 473	$ 778

Basis of Presentation and New A

Basis of Presentation and New Accounting Pronouncements	6 Months Ended
	Jun. 27, 2020
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 financial information as of December 28, 2019 is derived from our 2019 Annual Report on Form 10-K. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2019 Annual Report on Form 10-K filed with the SEC on February 21, 2020. 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 2020 and 2019 each contain 52 weeks and the six months ended June 27, 2020 and June 29, 2019 each contained 26 weeks. Fiscal 2020 will end on December 26, 2020. Significant Accounting Policies Our significant accounting policies have not changed during the six months ended June 27, 2020 from those disclosed in our Annual Report on Form 10-K for the year ended December 28, 2019. Reclassifications Certain immaterial reclassifications were made to the prior year financial statements to conform to the current year presentation. New Accounting Pronouncements ASU 2016-13 In June 2016, the Financial Accounting Standard Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, "Measurement of Credit Losses on Financial Instruments (Topic 326)." The provisions of this standard require financial assets measured at amortized cost to be presented at the net amount expected to be collected. An allowance account would be established to present the net carrying value at the amount expected to be collected. ASU 2016-13 also provides that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. The guidance was amended through various ASU's subsequent to ASU 2016-13, all of which was effective for us beginning fiscal 2020. We adopted ASU 2016-13 on a prospective basis on December 29, 2019, the first day of fiscal 2020. The adoption did not have a material effect on our financial position, results of operations or cash flows. ASU 2018-15 In August 2018, the FASB issued ASU 2018-15, "Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract." The new guidance clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. We adopted ASU 2018-15 on a prospective basis on December 29, 2019, the first day of fiscal 2020. The adoption did not have a material effect on our financial position, results of operations or cash flows. ASU 2019-12 In December 2019, the FASB issued 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. Early adoption of the amendments is permitted, including adoption in any interim period for which financial statements have not yet been issued. Depending on the amendment, adoption may be applied on the retrospective, modified retrospective or prospective basis. We have not yet determined the impact of this standard on our financial position, results of operations or cash flows.

Concentration of Credit and Oth

Concentration of Credit and Other Risks	6 Months Ended
	Jun. 27, 2020
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 27, June 29, June 27, June 29, Intel Corporation 36.1 % 26.1 % 36.2 % 23.8 % Samsung Electronics., LTD. * 11.1 % * 12.4 % Micron Technology, Inc. * 10.1 % * * 36.1 % 47.3 % 36.2 % 36.2 % *Represents less than 10% of total revenues.

Inventories

Inventories	6 Months Ended
	Jun. 27, 2020
Inventory Disclosure [Abstract]
Inventories	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 27, December 28, Raw materials $ 39,743 $ 38,528 Work-in-progress 31,530 29,720 Finished goods 16,540 15,010 $ 87,813 $ 83,258

Acquisition

Acquisition	6 Months Ended
	Jun. 27, 2020
Business Combinations [Abstract]
Acquisition	Acquisition On October 9, 2019, we acquired 100% of the shares of FRT GmbH ("FRT"), a German-based company, for total consideration of $26.9 million, net of cash acquired of $1.7 million. The fair value of the purchase consideration was comprised of a $22.2 million cash payment and $6.5 million of contingent consideration as of October 9, 2019. We estimated the acquisition price and the allocation of fair value to assets acquired and liabilities assumed as of the acquisition date, October 9, 2019. We subsequently made certain immaterial adjustments to the acquisition price allocation related to acquired assets and assumed liabilities, including to intangibles assets. Our purchase accounting remains open at June 27, 2020, subject to finalization of the fair value of certain acquired assets and liabilities. The estimated fair value of assets acquired, including goodwill and intangibles, and liabilities assumed is as follows (in thousands): Amount Cash and cash equivalents $ 1,687 Accounts receivable 3,079 Inventory 2,643 Property, plant and equipment 696 Operating lease, right of use assets 335 Prepaid expenses and other current assets 838 Tangible assets acquired 9,278 Customer deposits (1,933) Accounts payable and accrued liabilities (1,182) Operating lease liabilities (335) Deferred tax liabilities (5,757) Total tangible assets acquired and liabilities assumed 71 Intangible assets 17,429 Goodwill 11,123 Net Assets Acquired $ 28,623 The intangible assets as of the closing date of the acquisition included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 12,505 8.0 Customer relationships 3,071 6.0 Backlog 1,645 0.5 Trade names 208 2.0 Total intangible assets $ 17,429 7.0 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. The contingent consideration is a cash amount equal to 1.5x Earnings Before Interest and Tax ("EBIT") as defined in the purchase agreement, from a minimum of zero up to a maximum of €10.3 million, payable subject to the performance of the acquired business in calendar 2020. For purchase accounting, we estimated the fair value of contingent consideration using a probability weighted approach. Key assumptions in determining the fair value of contingent consideration include estimating the probability of achieving certain EBIT levels and discounting at an appropriate discount rate. See Note 8, Fair Value and Derivative Instruments , for further discussion on the fair value of contingent consideration. This acquisition strengthens our leadership in test and measurement by expanding our addressable market into 3D hybrid surface metrology and extending the optical applications scope of our existing Systems segment. Separate from the purchase agreement, on October 25, 2019, we entered into a term loan agreement with a lender for an aggregate amount of $23.4 million to finance the acquisition. See Note 6, Debt , for further discussion of the term loan agreement. Identifiable Intangible Assets Valuation of intangible assets involves multiple assumptions. The key assumptions are described below. Developed technologies acquired primarily consists of existing technology related to hybrid 3D surface metrology measurement equipment. We valued the developed technologies 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. Customer relationships represent the fair value of future projected revenues that will be derived from the sale of products to FRT'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. Backlog represents business under existing contractual obligations. Expected cash flow from backlog was valued on a direct cash flow basis. The identified trade names intangible relates to the estimated fair value of future cash flows related to the FRT 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 FRT reporting unit within the Systems reportable segment. We have not presented unaudited combined pro forma financial information as the FRT 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. 27, 2020
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 29, 2018 $ 172,482 $ 16,732 $ 189,214 Addition - FRT GmbH Acquisition — 10,148 10,148 Foreign currency translation — (166) (166) Goodwill, gross, as of December 28, 2019 172,482 26,714 199,196 Addition - FRT GmbH Acquisition — 975 975 Foreign currency translation — 122 122 Goodwill, gross, as of June 27, 2020 $ 172,482 $ 27,811 $ 200,293 No goodwill impairments have been recorded during the six months ended June 27, 2020 and the twelve months ended December 28, 2019. Intangible assets were as follows (in thousands): June 27, 2020 December 28, 2019 Intangible Assets Gross Accumulated Amortization Net Gross Accumulated Amortization Net Developed technologies $ 155,766 $ 125,918 $ 29,848 $ 154,951 $ 116,138 $ 38,813 Trade names 7,817 7,125 692 7,816 6,976 840 Customer relationships 43,217 29,972 13,245 44,229 27,057 17,172 Backlog 1,682 1,682 — 1,676 891 785 $ 208,482 $ 164,697 $ 43,785 $ 208,672 $ 151,062 $ 57,610 Amortization expense was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended Six Months Ended June 27, June 29, June 27, June 29, Cost of revenues $ 4,926 $ 4,711 $ 10,676 $ 9,430 Selling, general and administrative 1,528 2,368 3,041 4,739 $ 6,454 $ 7,079 $ 13,717 $ 14,169 The estimated future amortization of intangible assets is as follows (in thousands): Fiscal Year Amount Remainder of 2020 $ 12,551 2021 14,796 2022 5,605 2023 3,864 2024 2,122 Thereafter 4,847 $ 43,785

Debt

Debt	6 Months Ended
	Jun. 27, 2020
Debt Disclosure [Abstract]
Debt	Debt Our debt consisted of the following (in thousands): June 27, December 28, Term loans $ 50,128 $ 58,514 Less unamortized issuance costs (78) (29) Term loans less issuance costs $ 50,050 $ 58,485 Future principal and interest payments on our term loans as of June 27, 2020, based on the interest rate in effect at that date were as follows (in thousands): Payments Due In Fiscal Year Remainder 2020 2021 2022 2023 2024 Thereafter Total Term loans - principal payments $ 16,912 $ 8,845 $ 8,873 $ 1,050 $ 1,080 $ 13,368 $ 50,128 Term loans - interest payments (1) 328 537 392 293 273 1,445 3,268 Total $ 17,240 $ 9,382 $ 9,265 $ 1,343 $ 1,353 $ 14,813 $ 53,396 (1) Represents our minimum interest payment commitments at 1.92% per annum for the Building Term Loan and 1.59% per annum for the FRT Term Loan and 2.18% per annum for the CMI Term Loan. CMI Term Loan On June 24, 2016, we entered into a Credit Agreement (the “Credit Agreement”) with HSBC Bank USA, National Association ("HSBC"), as administrative agent, co-lead arranger, sole bookrunner and syndication agent, other lenders that may from time-to-time be a party to the Credit Agreement, and certain guarantors. Pursuant to the Credit Agreement, the lenders have provided us with a senior secured term loan facility of $150 million (the “CMI Term Loan”). The proceeds of the CMI Term Loan were used to finance a portion of the purchase price paid in connection with the Cascade Microtech acquisition in fiscal 2016 and to pay related bank fees and expenses. The CMI Term Loan bears interest at a rate equal to, at our option, (i) the applicable London Interbank Offered Rate ("LIBOR") rate plus 2.00% per annum or (ii) Base Rate (as defined in the Credit Agreement) plus 1.00% per annum. We have currently elected to pay interest at 2.00% over the one-month LIBOR rate. Interest payments are payable in monthly installments over a five-year period. The interest rate at June 27, 2020 was 2.41%. The principal payments on the CMI Term Loan are paid in equal quarterly installments that began June 30, 2016, in an annual amount equal to 5% for year one, 10% for year two, 20% for year three, 30% for year four and 35% for year five. The planned final payment on the CMI Term Loan is scheduled for the third quarter of fiscal 2020. On July 25, 2016, we entered into an interest rate swap agreement with HSBC and other lenders to hedge the interest payments on the CMI Term Loan for the notional amount of $95.6 million. As future levels of LIBOR over the life of the loan are uncertain, we entered into these interest-rate swap agreements to hedge the exposure in interest rate risks associated with movement in LIBOR rates. By entering into the agreements, we convert a floating rate interest at one-month LIBOR plus 2% into a fixed rate interest at 2.939%. The interest rate swap agreement ended as of March 27, 2020. The obligations under the Term Loan are guaranteed by substantially all of our assets and the assets of our domestic subsidiaries, subject to certain customary exceptions. The Credit Agreement contains negative covenants customary for financing of this type, as well as certain financial maintenance covenants. As of June 27, 2020, the balance outstanding pursuant to the CMI Term Loan was $12.5 million and we were in compliance with all covenants under the Credit Agreement. The CMI Term loan was subsequently fully paid as of June 30, 2020. FRT Term Loan On October 25, 2019, we entered into a $23.4 million three-year credit facility loan agreement (the "FRT Term Loan") with HSBC Trinkaus & Burkhardt AG, Germany, to fund the acquisition of FRT GmbH, which we acquired on October 9, 2019. See Note 4, Acquisition, for further details of the acquisition. The FRT Term Loan bears interest at a rate equal to the Euro Interbank Offered Rate ("EURIBOR") plus 1.75% per annum and will be repaid in quarterly installments of approximately $1.9 million plus interest. The interest rate at June 27, 2020 was 1.36% The obligations under the FRT Term Loan are fully and unconditionally guaranteed by FormFactor, Inc. The FRT Term Loan contains negative covenants customary for financing of this type, including covenants that place limitations on the incurrence of additional indebtedness, the creation of liens, the payment of dividends; dispositions; fundamental changes, including mergers and acquisitions; loans and investments; sale leasebacks; negative pledges; transactions with affiliates; changes in fiscal year; sanctions and anti-bribery laws and regulations, and modifications to charter documents in a manner materially adverse to the Lenders. The FRT Term Loan also contains affirmative covenants and representations and warranties customary for financing of this type. As of June 27, 2020, the balance outstanding pursuant to the FRT term loan was $19.6 million and we were in compliance with all covenants. Building Term Loan On June 22, 2020, we entered into an $18.0 million 15-year credit facility loan agreement (the “Building Term Loan”) with MUFG Union Bank, National Association ("Union Bank"). The proceeds of the Building Term Loan were used to purchase a building adjacent to our leased facilities in Livermore, California. The Building Term Loan bears interest at a rate equal to the applicable LIBOR rate plus 1.75% per annum. Interest payments are payable in monthly installments over a fifteen On March 17, 2020, we entered into an interest rate swap agreement with Union Bank to hedge the interest payments on the Building Term Loan for the notional amount of $18.0 million. As future levels of LIBOR over the life of the loan are uncertain, we entered into this interest-rate swap agreement to hedge the exposure in interest rate risks associated with movement in LIBOR rates. By entering into the agreement, we convert a floating rate interest at one-month LIBOR plus 1.75% into a fixed rate interest at 2.75%. The interest rate swap also includes a 0% floor that is effective for one year from the date of the swap. As of June 27, 2020, the notional amount of the loan that is subject to this interest rate swap is $18.0 million. See Note 8, Fair Value and Derivative Instruments , for additional information. The obligations under the Building Term Loan are guaranteed by a deed of trust covering certain real property and improvements and certain personal property used in connection therewith. The deed of trust creates a first priority lien or encumbrance on the property with only such exceptions as may be approved by the Union Bank in writing.

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 27, 2020
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following (in thousands): June 27, December 28, Accrued compensation and benefits $ 24,269 $ 21,329 Accrued income and other taxes 4,850 6,846 Accrued warranty 2,061 1,942 Accrued employee stock purchase plan contributions withheld 3,678 3,331 Other accrued expenses 2,762 2,991 $ 37,620 $ 36,439

Fair Value and Derivative Instr

Fair Value and Derivative Instruments	6 Months Ended
	Jun. 27, 2020
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 27, 2020 or the year ended December 28, 2019. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and Current portion of 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 2020. 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 27, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 96,474 $ — $ — $ 96,474 Marketable securities: U.S. treasuries 33,279 — — 33,279 Certificates of deposit — 3,157 — 3,157 U.S. agency securities — 2,643 — 2,643 Corporate bonds — 19,949 — 19,949 Commercial paper — 2,149 — 2,149 33,279 27,898 — 61,177 Foreign exchange derivative contracts — 153 — 153 Total assets $ 129,753 $ 28,051 $ — $ 157,804 Liabilities: Interest rate swap derivative contracts $ — $ (256) $ — $ (256) Contingent consideration — — (2,862) (2,862) Total liabilities $ — $ (256) $ (2,862) $ (3,118) December 28, 2019 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 17,056 $ — $ — $ 17,056 Marketable securities: U.S. treasuries 10,468 — — 10,468 Certificates of deposit — 3,590 — 3,590 U.S. agency securities — 24,430 — 24,430 Corporate bonds — 33,928 — 33,928 Commercial paper — 3,911 — 3,911 10,468 65,859 — 76,327 Foreign exchange derivative contracts — 41 — 41 Interest rate swap derivative contracts — 26 — 26 Total assets $ 27,524 $ 65,926 $ — $ 93,450 Liabilities: Foreign exchange derivative contracts $ — $ (240) $ — $ (240) Contingent consideration — — (5,364) (5,364) Total liabilities $ — $ (240) $ (5,364) $ (5,604) 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, is 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 include estimating EBIT levels that are likely to be achieved during the performance period and discounting at an appropriate discount rate. Contingent consideration as of June 27, 2020 was estimated to be $2.9 million, a net decrease of $2.5 million from $5.4 million as of December 28, 2019. The net decrease was as a result of a $1.2 million increase in the estimated contingent consideration upon acquisition and as part of purchase accounting that was adjusted in the first fiscal quarter of 2020, offset by a $3.7 million decrease in the estimated contingent consideration from subsequent remeasurement of the liability. 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 27, 2020 $ (174) Interest expense $ (10) Interest expense $ — Three Months Ended June 29, 2019 $ (62) Interest expense $ 175 Interest expense $ — Six Months Ended June 27, 2020 $ (270) Interest expense $ 12 Interest expense $ — Six Months Ended June 29, 2019 $ (90) Interest expense $ 383 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 loss 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. At June 27, 2020, we expect to reclassify $0.2 million of the amount accumulated in Other comprehensive loss to earnings during the next 12 months, due to the recognition in earnings of the hedged forecasted transactions. 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 27, 2020 will mature by the second quarter of fiscal 2021. The following table provides information about our foreign currency forward contracts outstanding as of June 27, 2020 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (1,897) $ (1,996) Japanese Yen Sell 1,475,099 13,766 Korean Won Buy (2,613,516) (2,182) Total USD notional amount of outstanding foreign exchange contracts $ 9,588 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 27, June 29, June 27, June 29, Foreign exchange forward contracts Other expense, net $ 234 $ 587 $ 349 $ 273 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 Loss Recognized in Accumulated OCI on Derivative Location of Loss Reclassified from Accumulated OCI into Income Amount of Loss Reclassified from Accumulated OCI into Income Three Months Ended June 27, 2020 $ 52 Cost of revenues $ 139 Research and development 17 Selling, general and administrative 35 $ 191 Three Months Ended June 29, 2019 $ 213 Cost of revenues $ 139 Research and development 12 Selling, general and administrative 32 $ 183 Six Months Ended June 27, 2020 $ 126 Cost of revenues $ 258 Research and development 35 Selling, general and administrative 79 $ 372 Six Months Ended June 29, 2019 $ 213 Cost of revenues $ 171 Research and development 19 Selling, general and administrative 51 $ 241 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. 27, 2020
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 27, June 29, Balance at beginning of period $ 1,942 $ 2,102 Accruals 2,116 1,648 Settlements (1,997) (1,923) Balance at end of period $ 2,061 $ 1,827

Property, Plant, and Equipment,

Property, Plant, and Equipment, net	6 Months Ended
	Jun. 27, 2020
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 27, December 28, Land $ 4,751 $ — Machinery and equipment 207,199 201,861 Computer equipment and software 35,844 35,192 Furniture and fixtures 6,938 6,756 Leasehold improvements 77,470 76,081 Sub-total 332,202 319,890 Less: Accumulated depreciation and amortization (281,539) (273,001) Net, property, plant and equipment 50,663 46,889 Construction-in-process 32,999 11,858 Total $ 83,662 $ 58,747

Stockholders_ Equity and Stock-

Stockholders’ Equity and Stock-Based Compensation	6 Months Ended
	Jun. 27, 2020
Equity [Abstract]
Stockholders’ Equity and Stock-Based Compensation	Stockholders’ Equity and Stock-Based Compensation 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 28, 2019 3,069,000 $ 14.30 Awards granted 65,686 23.92 Awards vested (465,440) 14.84 Awards forfeited (29,552) 14.23 RSUs at June 27, 2020 2,639,694 14.45 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 27, 2020. 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 28, 2019 361,769 $ 8.35 Options exercised (105,769) 8.21 Outstanding at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740 Vested and expected to vest at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740 Exercisable at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740 Employee Stock Purchase Plan Information related to activity under our Employee Stock Purchase Plan ("ESPP") was as follows: Six Months Ended June 27, 2020 Shares issued 311,591 Weighted average per share purchase price $ 13.05 Weighted average per share discount from the fair value of our common stock on the date of issuance $ 12.26 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 27, June 29, June 27, June 29, Cost of revenues $ 901 $ 964 $ 1,838 $ 1,914 Research and development 1,389 1,582 2,828 3,101 Selling, general and administrative 3,352 2,743 6,599 5,569 Total stock-based compensation $ 5,642 $ 5,289 $ 11,265 $ 10,584 Unrecognized Compensation Costs At June 27, 2020, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 17,242 1.61 Performance restricted stock units 4,518 1.64 Employee stock purchase plan 165 0.10 Total unrecognized stock-based compensation expense $ 21,925 1.61

Net Income per Share

Net Income per Share	6 Months Ended
	Jun. 27, 2020
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 27, June 29, June 27, June 29, Weighted-average shares used in computing basic net income per share 76,275 74,478 76,140 74,483 Add potentially dilutive securities 2,586 1,711 2,570 1,578 Weighted-average shares used in computing diluted net income per share 78,861 76,189 78,710 76,061 Securities not included as they would have been antidilutive — 263 13 252

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 27, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases See Note 14, Leases . Contractual Obligations and Commitments Our contractual obligations and commitments have not materially changed as of June 27, 2020 from those disclosed in our Annual Report on Form 10-K for the year ended December 28, 2019. Legal Matters

Leases

Leases	6 Months Ended
	Jun. 27, 2020
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 15 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 7 years as of June 27, 2020 and the weighted-average discount rate was 4.70%. The components of lease expense were as follows (in thousands): Three Months Ended Six Months Ended June 27, June 29, June 27, June 29, Lease expense: Operating lease expense $ 1,794 $ 1,734 $ 3,719 $ 3,479 Short-term lease expense 27 31 66 48 Variable lease expense 399 249 782 668 $ 2,220 $ 2,014 $ 4,567 $ 4,195 Future minimum payments under our non-cancelable operating leases were as follows as of June 27, 2020 (in thousands): Fiscal Year Amount Remainder of 2020 $ 3,532 2021 6,275 2022 5,084 2023 4,446 2024 4,261 Thereafter 16,150 Total minimum lease payments 39,748 Less: interest (6,764) Present value of net minimum lease payments 32,984 Less: current portion (6,168) Total long-term operating lease liabilities $ 26,816

Revenue

Revenue	6 Months Ended
	Jun. 27, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Transaction price allocated to the remaining performance obligations: On June 27, 2020, we had $3.9 million of remaining performance obligations, which were comprised of deferred service contracts and extended warranty contracts not yet delivered. We expect to recognize approximately 55.6% of our remaining performance obligations as revenue in the remainder of fiscal 2020, approximately 29.6% in fiscal 2021, and approximately 14.8% in fiscal 2022 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 27, 2020 and December 28, 2019 were $4.3 million and $0.9 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 27, 2020 and December 28, 2019 were $14.7 million and $10.8 million, respectively. During the six months ended June 27, 2020, we recognized $7.2 million of revenue, that was included in contract liabilities as of December 28, 2019. 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 16, Operating Segments and Enterprise-Wide Information

Operating Segments and Enterpri

Operating Segments and Enterprise-Wide Information	6 Months Ended
	Jun. 27, 2020
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 27, 2020 June 29, 2019 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 133,784 $ 24,040 $ — $ 157,824 $ 113,637 $ 24,381 $ — $ 138,018 Gross profit $ 61,523 $ 10,719 $ (6,075) $ 66,167 $ 48,492 $ 12,672 $ (5,812) $ 55,352 Gross margin 46.0 % 44.6 % — % 41.9 % 42.7 % 52.0 % — % 40.1 % Six Months Ended June 27, 2020 June 29, 2019 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 268,499 $ 50,078 $ — $ 318,577 $ 221,740 $ 48,491 $ — $ 270,231 Gross profit 122,266 24,053 (12,762) $ 133,557 $ 93,785 $ 25,688 $ (11,600) $ 107,873 Gross margin 45.5 % 48.0 % — % 41.9 % 42.3 % 53.0 % — % 39.9 % 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, share-based compensation, and restructuring charges, net, 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 27, 2020 June 29, 2019 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 109,347 $ — $ 109,347 $ 73,442 $ — $ 73,442 DRAM 19,052 — 19,052 36,044 — 36,044 Flash 5,385 — 5,385 4,151 — 4,151 Systems — 24,040 24,040 — 24,381 24,381 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Timing of revenue recognition: Products transferred at a point in time $ 133,208 $ 22,548 $ 155,756 $ 113,028 $ 23,339 $ 136,367 Services transferred over time 576 1,492 2,068 609 1,042 1,651 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Geographical region: China $ 45,625 $ 3,133 $ 48,758 $ 16,304 $ 4,051 $ 20,355 Taiwan 29,806 3,365 33,171 12,826 2,046 14,872 United States 22,368 5,753 28,121 32,072 6,297 38,369 South Korea 14,249 864 15,113 27,360 811 28,171 Europe 8,767 5,365 14,132 4,474 6,174 10,648 Japan 6,679 3,380 10,059 12,867 3,226 16,093 Asia-Pacific 1 4,347 2,153 6,500 6,262 1,421 7,683 Rest of the world 1,943 27 1,970 1,472 355 1,827 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Six Months Ended June 27, 2020 June 29, 2019 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 215,092 $ — $ 215,092 $ 145,022 $ — $ 145,022 DRAM 43,748 — 43,748 64,930 — 64,930 Flash 9,659 — 9,659 11,788 — 11,788 Systems — 50,078 50,078 — 48,491 48,491 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 Timing of revenue recognition: Products transferred at a point in time $ 267,277 $ 47,406 $ 314,683 $ 220,519 $ 46,481 $ 267,000 Services transferred over time 1,222 2,672 3,894 1,221 2,010 3,231 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 Geographical region: China $ 82,905 $ 9,495 $ 92,400 $ 34,455 $ 7,743 $ 42,198 Taiwan 60,245 4,706 64,951 34,083 3,176 37,259 United States 47,979 12,058 60,037 59,727 12,905 72,632 Europe 24,977 10,198 35,175 9,847 10,294 20,141 South Korea 27,941 1,260 29,201 52,378 2,516 54,894 Japan 12,214 6,215 18,429 18,167 8,358 26,525 Asia-Pacific 1 8,802 5,561 14,363 9,052 1,894 10,946 Rest of the world 3,436 585 4,021 4,031 1,605 5,636 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 1 Asia-Pacific includes all countries in the region except China, Japan, South Korea, and Taiwan, which are disclosed separately.

Subsequent Event (Notes)

Subsequent Event (Notes)	6 Months Ended
	Jun. 27, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On July 30, 2020, subsequent to the balance sheet date, we acquired the probe card assets of Advantest Corporation for total consideration of $35.0 million. This acquisition brings important enabling technologies and capabilities for designing and manufacturing advanced memory 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 transaction will be accounted for in accordance with the acquisition method of accounting which requires, among other things, that assets acquired and liabilities assumed be recognized at their fair values as of the acquisition date. Due to the limited time since the acquisition date, the initial purchase allocation for the business combination is incomplete at this time. Disclosures regarding amounts recognized for major classes of assets acquired and liabilities assumed will be provided once the initial accounting is completed. The acquired business is not expected to be material to the Company’s operations and consolidated financial position.

Basis of Presentation and New_2

Basis of Presentation and New Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 27, 2020
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 financial information as of December 28, 2019 is derived from our 2019 Annual Report on Form 10-K. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2019 Annual Report on Form 10-K filed with the SEC on February 21, 2020. 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 2020 and 2019 each contain 52 weeks and the six months ended June 27, 2020 and June 29, 2019 each contained 26 weeks. Fiscal 2020 will end on December 26, 2020.
New Accounting Pronouncements	New Accounting Pronouncements ASU 2016-13 In June 2016, the Financial Accounting Standard Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, "Measurement of Credit Losses on Financial Instruments (Topic 326)." The provisions of this standard require financial assets measured at amortized cost to be presented at the net amount expected to be collected. An allowance account would be established to present the net carrying value at the amount expected to be collected. ASU 2016-13 also provides that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. The guidance was amended through various ASU's subsequent to ASU 2016-13, all of which was effective for us beginning fiscal 2020. We adopted ASU 2016-13 on a prospective basis on December 29, 2019, the first day of fiscal 2020. The adoption did not have a material effect on our financial position, results of operations or cash flows. ASU 2018-15 In August 2018, the FASB issued ASU 2018-15, "Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract." The new guidance clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. We adopted ASU 2018-15 on a prospective basis on December 29, 2019, the first day of fiscal 2020. The adoption did not have a material effect on our financial position, results of operations or cash flows. ASU 2019-12 In December 2019, the FASB issued 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. Early adoption of the amendments is permitted, including adoption in any interim period for which financial statements have not yet been issued. Depending on the amendment, adoption may be applied on the retrospective, modified retrospective or prospective basis. We have not yet determined the impact of this standard on our financial position, results of operations or cash flows.
Fair Value Policy	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 27, 2020 or the year ended December 28, 2019. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and Current portion of 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 2020. 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

Concentration of Credit and O_2

Concentration of Credit and Other Risks (Tables)	6 Months Ended
	Jun. 27, 2020
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 27, June 29, June 27, June 29, Intel Corporation 36.1 % 26.1 % 36.2 % 23.8 % Samsung Electronics., LTD. * 11.1 % * 12.4 % Micron Technology, Inc. * 10.1 % * * 36.1 % 47.3 % 36.2 % 36.2 % *Represents less than 10% of total revenues.

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 27, 2020
Inventory Disclosure [Abstract]
Schedule of Inventory Components	Inventories, net, consisted of the following (in thousands): June 27, December 28, Raw materials $ 39,743 $ 38,528 Work-in-progress 31,530 29,720 Finished goods 16,540 15,010 $ 87,813 $ 83,258

Acquisition (Tables)

Acquisition (Tables)	6 Months Ended
	Jun. 27, 2020
Business Combinations [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 $ 1,687 Accounts receivable 3,079 Inventory 2,643 Property, plant and equipment 696 Operating lease, right of use assets 335 Prepaid expenses and other current assets 838 Tangible assets acquired 9,278 Customer deposits (1,933) Accounts payable and accrued liabilities (1,182) Operating lease liabilities (335) Deferred tax liabilities (5,757) Total tangible assets acquired and liabilities assumed 71 Intangible assets 17,429 Goodwill 11,123 Net Assets Acquired $ 28,623
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 $ 12,505 8.0 Customer relationships 3,071 6.0 Backlog 1,645 0.5 Trade names 208 2.0 Total intangible assets $ 17,429 7.0

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 27, 2020
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 29, 2018 $ 172,482 $ 16,732 $ 189,214 Addition - FRT GmbH Acquisition — 10,148 10,148 Foreign currency translation — (166) (166) Goodwill, gross, as of December 28, 2019 172,482 26,714 199,196 Addition - FRT GmbH Acquisition — 975 975 Foreign currency translation — 122 122 Goodwill, gross, as of June 27, 2020 $ 172,482 $ 27,811 $ 200,293
Schedule of Intangible Assets	Intangible assets were as follows (in thousands): June 27, 2020 December 28, 2019 Intangible Assets Gross Accumulated Amortization Net Gross Accumulated Amortization Net Developed technologies $ 155,766 $ 125,918 $ 29,848 $ 154,951 $ 116,138 $ 38,813 Trade names 7,817 7,125 692 7,816 6,976 840 Customer relationships 43,217 29,972 13,245 44,229 27,057 17,172 Backlog 1,682 1,682 — 1,676 891 785 $ 208,482 $ 164,697 $ 43,785 $ 208,672 $ 151,062 $ 57,610
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 27, June 29, June 27, June 29, Cost of revenues $ 4,926 $ 4,711 $ 10,676 $ 9,430 Selling, general and administrative 1,528 2,368 3,041 4,739 $ 6,454 $ 7,079 $ 13,717 $ 14,169
Schedule of Estimated Amortization of Intangible Assets	The estimated future amortization of intangible assets is as follows (in thousands): Fiscal Year Amount Remainder of 2020 $ 12,551 2021 14,796 2022 5,605 2023 3,864 2024 2,122 Thereafter 4,847 $ 43,785

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 27, 2020
Debt Disclosure [Abstract]
Schedule of Debt	Our debt consisted of the following (in thousands): June 27, December 28, Term loans $ 50,128 $ 58,514 Less unamortized issuance costs (78) (29) Term loans less issuance costs $ 50,050 $ 58,485
Schedule of Maturities of Long-term Debt	Future principal and interest payments on our term loans as of June 27, 2020, based on the interest rate in effect at that date were as follows (in thousands): Payments Due In Fiscal Year Remainder 2020 2021 2022 2023 2024 Thereafter Total Term loans - principal payments $ 16,912 $ 8,845 $ 8,873 $ 1,050 $ 1,080 $ 13,368 $ 50,128 Term loans - interest payments (1) 328 537 392 293 273 1,445 3,268 Total $ 17,240 $ 9,382 $ 9,265 $ 1,343 $ 1,353 $ 14,813 $ 53,396

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 27, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	Accrued liabilities consisted of the following (in thousands): June 27, December 28, Accrued compensation and benefits $ 24,269 $ 21,329 Accrued income and other taxes 4,850 6,846 Accrued warranty 2,061 1,942 Accrued employee stock purchase plan contributions withheld 3,678 3,331 Other accrued expenses 2,762 2,991 $ 37,620 $ 36,439

Fair Value and Derivative Ins_2

Fair Value and Derivative Instruments (Tables)	6 Months Ended
	Jun. 27, 2020
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 27, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 96,474 $ — $ — $ 96,474 Marketable securities: U.S. treasuries 33,279 — — 33,279 Certificates of deposit — 3,157 — 3,157 U.S. agency securities — 2,643 — 2,643 Corporate bonds — 19,949 — 19,949 Commercial paper — 2,149 — 2,149 33,279 27,898 — 61,177 Foreign exchange derivative contracts — 153 — 153 Total assets $ 129,753 $ 28,051 $ — $ 157,804 Liabilities: Interest rate swap derivative contracts $ — $ (256) $ — $ (256) Contingent consideration — — (2,862) (2,862) Total liabilities $ — $ (256) $ (2,862) $ (3,118) December 28, 2019 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 17,056 $ — $ — $ 17,056 Marketable securities: U.S. treasuries 10,468 — — 10,468 Certificates of deposit — 3,590 — 3,590 U.S. agency securities — 24,430 — 24,430 Corporate bonds — 33,928 — 33,928 Commercial paper — 3,911 — 3,911 10,468 65,859 — 76,327 Foreign exchange derivative contracts — 41 — 41 Interest rate swap derivative contracts — 26 — 26 Total assets $ 27,524 $ 65,926 $ — $ 93,450 Liabilities: Foreign exchange derivative contracts $ — $ (240) $ — $ (240) Contingent consideration — — (5,364) (5,364) Total liabilities $ — $ (240) $ (5,364) $ (5,604)
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 27, 2020 $ (174) Interest expense $ (10) Interest expense $ — Three Months Ended June 29, 2019 $ (62) Interest expense $ 175 Interest expense $ — Six Months Ended June 27, 2020 $ (270) Interest expense $ 12 Interest expense $ — Six Months Ended June 29, 2019 $ (90) Interest expense $ 383 Interest expense $ —
Schedule of Foreign Currency Forward Contracts	The following table provides information about our foreign currency forward contracts outstanding as of June 27, 2020 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (1,897) $ (1,996) Japanese Yen Sell 1,475,099 13,766 Korean Won Buy (2,613,516) (2,182) Total USD notional amount of outstanding foreign exchange contracts $ 9,588 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 Loss Recognized in Accumulated OCI on Derivative Location of Loss Reclassified from Accumulated OCI into Income Amount of Loss Reclassified from Accumulated OCI into Income Three Months Ended June 27, 2020 $ 52 Cost of revenues $ 139 Research and development 17 Selling, general and administrative 35 $ 191 Three Months Ended June 29, 2019 $ 213 Cost of revenues $ 139 Research and development 12 Selling, general and administrative 32 $ 183 Six Months Ended June 27, 2020 $ 126 Cost of revenues $ 258 Research and development 35 Selling, general and administrative 79 $ 372 Six Months Ended June 29, 2019 $ 213 Cost of revenues $ 171 Research and development 19 Selling, general and administrative 51 $ 241
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 27, June 29, June 27, June 29, Foreign exchange forward contracts Other expense, net $ 234 $ 587 $ 349 $ 273

Warranty (Tables)

Warranty (Tables)	6 Months Ended
	Jun. 27, 2020
Product Warranties Disclosures [Abstract]
Reconciliation of Changes in Warranty Liability	Changes in our warranty liability were as follows (in thousands): Six Months Ended June 27, June 29, Balance at beginning of period $ 1,942 $ 2,102 Accruals 2,116 1,648 Settlements (1,997) (1,923) Balance at end of period $ 2,061 $ 1,827

Property, Plant, and Equipmen_2

Property, Plant, and Equipment, net (Tables)	6 Months Ended
	Jun. 27, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment, net consisted of the following (in thousands): June 27, December 28, Land $ 4,751 $ — Machinery and equipment 207,199 201,861 Computer equipment and software 35,844 35,192 Furniture and fixtures 6,938 6,756 Leasehold improvements 77,470 76,081 Sub-total 332,202 319,890 Less: Accumulated depreciation and amortization (281,539) (273,001) Net, property, plant and equipment 50,663 46,889 Construction-in-process 32,999 11,858 Total $ 83,662 $ 58,747

Stockholders_ Equity and Stoc_2

Stockholders’ Equity and Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 27, 2020
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 28, 2019 3,069,000 $ 14.30 Awards granted 65,686 23.92 Awards vested (465,440) 14.84 Awards forfeited (29,552) 14.23 RSUs at June 27, 2020 2,639,694 14.45
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 28, 2019 361,769 $ 8.35 Options exercised (105,769) 8.21 Outstanding at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740 Vested and expected to vest at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740 Exercisable at June 27, 2020 256,000 $ 8.41 1.63 $ 4,816,740
Schedule of ESPP Activity	Information related to activity under our Employee Stock Purchase Plan ("ESPP") was as follows: Six Months Ended June 27, 2020 Shares issued 311,591 Weighted average per share purchase price $ 13.05 Weighted average per share discount from the fair value of our common stock on the date of issuance $ 12.26
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 27, June 29, June 27, June 29, Cost of revenues $ 901 $ 964 $ 1,838 $ 1,914 Research and development 1,389 1,582 2,828 3,101 Selling, general and administrative 3,352 2,743 6,599 5,569 Total stock-based compensation $ 5,642 $ 5,289 $ 11,265 $ 10,584
Schedule of Unrecognized Stock-based Compensation	At June 27, 2020, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 17,242 1.61 Performance restricted stock units 4,518 1.64 Employee stock purchase plan 165 0.10 Total unrecognized stock-based compensation expense $ 21,925 1.61

Net Income per Share (Tables)

Net Income per Share (Tables)	6 Months Ended
	Jun. 27, 2020
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 27, June 29, June 27, June 29, Weighted-average shares used in computing basic net income per share 76,275 74,478 76,140 74,483 Add potentially dilutive securities 2,586 1,711 2,570 1,578 Weighted-average shares used in computing diluted net income per share 78,861 76,189 78,710 76,061 Securities not included as they would have been antidilutive — 263 13 252

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 27, 2020
Leases [Abstract]
Components of Lease Expense	The components of lease expense were as follows (in thousands): Three Months Ended Six Months Ended June 27, June 29, June 27, June 29, Lease expense: Operating lease expense $ 1,794 $ 1,734 $ 3,719 $ 3,479 Short-term lease expense 27 31 66 48 Variable lease expense 399 249 782 668 $ 2,220 $ 2,014 $ 4,567 $ 4,195
Schedule of Future Minimum Payments Under Leases	Future minimum payments under our non-cancelable operating leases were as follows as of June 27, 2020 (in thousands): Fiscal Year Amount Remainder of 2020 $ 3,532 2021 6,275 2022 5,084 2023 4,446 2024 4,261 Thereafter 16,150 Total minimum lease payments 39,748 Less: interest (6,764) Present value of net minimum lease payments 32,984 Less: current portion (6,168) Total long-term operating lease liabilities $ 26,816

Operating Segments and Enterp_2

Operating Segments and Enterprise-Wide Information (Tables)	6 Months Ended
	Jun. 27, 2020
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 27, 2020 June 29, 2019 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 133,784 $ 24,040 $ — $ 157,824 $ 113,637 $ 24,381 $ — $ 138,018 Gross profit $ 61,523 $ 10,719 $ (6,075) $ 66,167 $ 48,492 $ 12,672 $ (5,812) $ 55,352 Gross margin 46.0 % 44.6 % — % 41.9 % 42.7 % 52.0 % — % 40.1 % Six Months Ended June 27, 2020 June 29, 2019 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 268,499 $ 50,078 $ — $ 318,577 $ 221,740 $ 48,491 $ — $ 270,231 Gross profit 122,266 24,053 (12,762) $ 133,557 $ 93,785 $ 25,688 $ (11,600) $ 107,873 Gross margin 45.5 % 48.0 % — % 41.9 % 42.3 % 53.0 % — % 39.9 %
Disaggregation of Revenue by Segment	Certain revenue category information by reportable segment was as follows (in thousands): Three Months Ended June 27, 2020 June 29, 2019 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 109,347 $ — $ 109,347 $ 73,442 $ — $ 73,442 DRAM 19,052 — 19,052 36,044 — 36,044 Flash 5,385 — 5,385 4,151 — 4,151 Systems — 24,040 24,040 — 24,381 24,381 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Timing of revenue recognition: Products transferred at a point in time $ 133,208 $ 22,548 $ 155,756 $ 113,028 $ 23,339 $ 136,367 Services transferred over time 576 1,492 2,068 609 1,042 1,651 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Geographical region: China $ 45,625 $ 3,133 $ 48,758 $ 16,304 $ 4,051 $ 20,355 Taiwan 29,806 3,365 33,171 12,826 2,046 14,872 United States 22,368 5,753 28,121 32,072 6,297 38,369 South Korea 14,249 864 15,113 27,360 811 28,171 Europe 8,767 5,365 14,132 4,474 6,174 10,648 Japan 6,679 3,380 10,059 12,867 3,226 16,093 Asia-Pacific 1 4,347 2,153 6,500 6,262 1,421 7,683 Rest of the world 1,943 27 1,970 1,472 355 1,827 Total $ 133,784 $ 24,040 $ 157,824 $ 113,637 $ 24,381 $ 138,018 Six Months Ended June 27, 2020 June 29, 2019 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 215,092 $ — $ 215,092 $ 145,022 $ — $ 145,022 DRAM 43,748 — 43,748 64,930 — 64,930 Flash 9,659 — 9,659 11,788 — 11,788 Systems — 50,078 50,078 — 48,491 48,491 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 Timing of revenue recognition: Products transferred at a point in time $ 267,277 $ 47,406 $ 314,683 $ 220,519 $ 46,481 $ 267,000 Services transferred over time 1,222 2,672 3,894 1,221 2,010 3,231 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 Geographical region: China $ 82,905 $ 9,495 $ 92,400 $ 34,455 $ 7,743 $ 42,198 Taiwan 60,245 4,706 64,951 34,083 3,176 37,259 United States 47,979 12,058 60,037 59,727 12,905 72,632 Europe 24,977 10,198 35,175 9,847 10,294 20,141 South Korea 27,941 1,260 29,201 52,378 2,516 54,894 Japan 12,214 6,215 18,429 18,167 8,358 26,525 Asia-Pacific 1 8,802 5,561 14,363 9,052 1,894 10,946 Rest of the world 3,436 585 4,021 4,031 1,605 5,636 Total $ 268,499 $ 50,078 $ 318,577 $ 221,740 $ 48,491 $ 270,231 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_3

Basis of Presentation and New Accounting Pronouncements - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 26, 2020	Jun. 27, 2020	Dec. 25, 2022	Dec. 25, 2021	Dec. 28, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligations		$ 3.9
Contract assets		4.3			$ 0.9
Contract liabilities		14.7			$ 10.8
Revenue recognized included in contracts		$ 7.2
Forecast
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized	55.60%		14.80%	29.60%

Basis of Presentation and New_4

Basis of Presentation and New Accounting Pronouncements - ASU 2016-18 Information (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019	Jun. 29, 2019	Dec. 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents as previously reported in the Condensed Consolidated Statements of Cash Flows	$ 199,926	$ 144,545
Current assets - Restricted cash	1,424	1,981
Restricted cash	1,375	1,411
Cash, cash equivalents and restricted cash as currently reported in the Condensed Consolidated Statements of Cash Flows	$ 202,725	$ 147,937	$ 126,694	$ 100,546

Concentration of Credit and O_3

Concentration of Credit and Other Risks (Details) - Customer Concentration Risk	3 Months Ended			6 Months Ended
	Jun. 27, 2020	Mar. 28, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Revenue from Contract with Customer Benchmark
Concentration Risk [Line Items]
Concentration risk percentage	36.10%		47.30%	36.20%	36.20%
Revenue from Contract with Customer Benchmark | Intel Corporation
Concentration Risk [Line Items]
Concentration risk percentage	36.10%		26.10%	36.20%	23.80%
Revenue from Contract with Customer Benchmark | Samsung Electronics., LTD.
Concentration Risk [Line Items]
Concentration risk percentage			11.10%	12.40%
Revenue from Contract with Customer Benchmark | Micron Technology, Inc.
Concentration Risk [Line Items]
Concentration risk percentage			10.10%
Accounts Receivable | Major Customer 1
Concentration Risk [Line Items]
Concentration risk percentage		25.70%		15.80%
Accounts Receivable | Major Customer 2
Concentration Risk [Line Items]
Concentration risk percentage		15.10%		18.10%
Accounts Receivable | Major Customer 3
Concentration Risk [Line Items]
Concentration risk percentage		11.50%

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 39,743	$ 38,528
Work-in-progress	31,530	29,720
Finished goods	16,540	15,010
Inventories	$ 87,813	$ 83,258

Acquisition - Additional Inform

Acquisition - Additional Information (Details)	Oct. 09, 2019USD ($)	Jun. 27, 2020USD ($)	Dec. 28, 2019USD ($)	Oct. 25, 2019USD ($)	Oct. 09, 2019EUR (€)
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 22,200,000
Contingent consideration, liability		$ 2,862,000	$ 5,364,000
Fair Value, Inputs, Level 3 [Member]
Business Acquisition [Line Items]
Contingent consideration, liability	$ 6,500,000	2,862,000	$ 5,364,000
FRT Term Loan
Business Acquisition [Line Items]
Debt instrument, face amount				$ 23,400,000
FRT
Business Acquisition [Line Items]
Business Acquisition, percentage acquired	100.00%				100.00%
Cash and cash equivalents	$ 1,687,000
Contingent Consideration, Calculation Amount, Multiple of EBIT	150.00%
FRT | Selling, general and administrative
Business Acquisition [Line Items]
Transaction costs		$ 26,900,000
FRT | Maximum
Business Acquisition [Line Items]
Contingent consideration, liability | €					€ 10,300,000
FRT | Minimum
Business Acquisition [Line Items]
Contingent consideration, liability | €					€ 0

Acquisition - Assets Acquired a

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019	Oct. 09, 2019	Dec. 29, 2018
Business Acquisition [Line Items]
Goodwill	$ 200,293	$ 199,196		$ 189,214
FRT
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,687
Accounts receivable			3,079
Inventory			2,643
Property, plant and equipment			696
Operating lease, right of use assets			335
Prepaid expenses and other current assets			838
Tangible assets acquired			9,278
Customer deposits			(1,933)
Accounts payable and accrued liabilities			(1,182)
Operating lease liabilities			(335)
Deferred tax liabilities			(5,757)
Total tangible assets acquired and liabilities assumed			71
Intangible assets			17,429
Goodwill			11,123
Net Assets Acquired			$ 28,623

Acquisition - Intangible Assets

Acquisition - Intangible Assets Acquired (Details) - FRT $ in Thousands	Oct. 09, 2019USD ($)
Business Acquisition [Line Items]
Intangible assets	$ 17,429
Weighted Average Useful Life (in years)	7 years
Developed technologies
Business Acquisition [Line Items]
Amount	$ 12,505
Weighted Average Useful Life (in years)	8 years
Customer relationships
Business Acquisition [Line Items]
Amount	$ 3,071
Weighted Average Useful Life (in years)	6 years
Backlog
Business Acquisition [Line Items]
Amount	$ 1,645
Weighted Average Useful Life (in years)	6 months
Trade names
Business Acquisition [Line Items]
Amount	$ 208
Weighted Average Useful Life (in years)	2 years

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 27, 2020	Dec. 28, 2019
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 199,196	$ 189,214
Foreign currency translation	122	(166)
Goodwill, ending balance	200,293	199,196
Goodwill, Acquired During Period	975	10,148
Probe Cards
Goodwill [Roll Forward]
Goodwill, beginning balance	172,482	172,482
Foreign currency translation	0	0
Goodwill, ending balance	172,482	172,482
Goodwill, Acquired During Period	0	0
Systems
Goodwill [Roll Forward]
Goodwill, beginning balance	26,714	16,732
Foreign currency translation	122	(166)
Goodwill, ending balance	27,811	26,714
Goodwill, Acquired During Period	$ 975	$ 10,148

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	$ 208,482	$ 208,672
Accumulated Amortization	164,697	151,062
Intangible Assets, Net	43,785	57,610
Developed technologies
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	155,766	154,951
Accumulated Amortization	125,918	116,138
Intangible Assets, Net	29,848	38,813
Trade names
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	7,817	7,816
Accumulated Amortization	7,125	6,976
Intangible Assets, Net	692	840
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	43,217	44,229
Accumulated Amortization	29,972	27,057
Intangible Assets, Net	13,245	17,172
Backlog
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	1,682	1,676
Accumulated Amortization	1,682	891
Intangible Assets, Net	$ 0	$ 785

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019	Dec. 28, 2019
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 6,454	$ 7,079	$ 13,717	$ 14,169
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
Remainder of 2020	12,551		12,551
2019	14,796		14,796
2020	5,605		5,605
2021	3,864		3,864
2022	2,122		2,122
Intangible Assets, Net	43,785		43,785		$ 57,610
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	4,847		4,847
Cost of revenues
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	4,926	4,711	10,676	9,430
Selling, general and administrative
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 1,528	$ 2,368	$ 3,041	$ 4,739

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Jun. 27, 2020	Jun. 29, 2019
Debt Disclosure [Abstract]
Term loans		$ 50,128	$ 58,514
Less unamortized issuance costs	$ (78)		(29)
Term loans less issuance costs		$ 50,050	$ 58,485

Debt - Maturity Schedule (Detai

Debt - Maturity Schedule (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Jun. 29, 2019
Debt Instrument [Line Items]
Principal payments - Remainder of 2020	$ 16,912
Principal payments - 2021	8,845
Principal payments - 2022	8,873
Principal payments - 2023	1,050
Principal payments - 2024	1,080
Principal payments - Thereafter	13,368
Term loans	50,128	$ 58,514
Interest payments - Remainder of 2020	328
Interest payments - 2021	537
Interest payments - 2022	392
Interest payments - 2023	293
Interest payments - 2024	273
Interest payments - Thereafter	1,445
Interest payments - Total	3,268
Remainder 2020	17,240
2021	9,382
2022	9,265
2023	1,343
2024	1,353
Thereafter	14,813
Total	$ 53,396
Building Term Loan [Member] | Minimum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.92%
FRT Term Loan | Minimum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.59%
CMI Term Loan [Member] | Minimum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.18%

Debt - CMI Term Loan (Details)

Debt - CMI Term Loan (Details) - USD ($)	Jul. 25, 2016	Jun. 24, 2016	Jun. 27, 2020	Jun. 29, 2019
Debt Instrument [Line Items]
Long-term Debt			$ 50,050,000	$ 58,485,000
CMI Term Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 150,000,000
Debt Instrument, Interest Rate During Period			2.41%
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months, Percentage		5.00%
Long-term Debt, Maturities, Repayments of Principal in Year Two, Percentage		10.00%
Long-term Debt, Maturities, Repayments of Principal in Year Three, Percentage		20.00%
Long-term Debt, Maturities, Repayments of Principal in Year Four, Percentage		30.00%
Long-term Debt, Maturities, Repayments of Principal in Year Five, Percentage		35.00%
Derivative, notional amount		$ 95,600,000
Debt Instrument, Interest Rate, Effective Percentage	2.939%
Long-term Debt			$ 12,500,000
CMI Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%	2.00%	2.00%
CMI Term Loan [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%

Debt - FRT Term Loan (Details)

Debt - FRT Term Loan (Details) - USD ($)	Jun. 27, 2020	Oct. 25, 2019	Jun. 29, 2019
Debt Instrument [Line Items]
Long-term Debt	$ 50,050,000		$ 58,485,000
FRT Term Loan
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 23,400,000
Long-Term Line of Credit, Quarterly Repayment Amount		$ 1,900,000
Line of Credit Facility, Interest Rate at Period End	1.36%
Long-term Debt	$ 19,600,000
FRT Term Loan | Euro Interbank Offered Rate [Member]
Debt Instrument [Line Items]
Derivative, Basis Spread on Variable Rate		1.75%

Debt - Building Term Loan (Deta

Debt - Building Term Loan (Details) - USD ($)	Jun. 22, 2020	Mar. 17, 2020	Jun. 27, 2020	Jun. 29, 2019
Debt Instrument [Line Items]
Long-term Debt			$ 50,050,000	$ 58,485,000
Building Term Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 18,000,000
Long-term Debt, Term	15 years
Debt Instrument, Interest Payment Term	15 years
Line of Credit Facility, Interest Rate at Period End			1.92%
Debt Instrument, Interest Rate, Effective Percentage		2.75%
Long-term Debt			$ 18,000,000
Building Term Loan [Member] | Interest Rate Contract [Member]
Debt Instrument [Line Items]
Derivative, notional amount			$ 18,000,000
Derivative, Floor Interest Rate		0.00%
Building Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%	1.75%

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 24,269	$ 21,329
Accrued warranty	3,678	3,331
Accrued employee stock purchase plan contributions withheld	2,061	1,942
Accrued income and other taxes	4,850	6,846
Other accrued expenses	2,762	2,991
Accrued liabilities	$ 37,620	$ 36,439

Fair Value and Derivative Ins_3

Fair Value and Derivative Instruments - Fair Value Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019	Oct. 09, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 61,177
Total assets measured at fair value	157,804	$ 93,450
Contingent consideration, liability	2,862	5,364
Liabilities measured at fair value on recurring basis	3,118	5,604
Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities		76,327
Derivative contracts	153	(41)
Derivative Liability		240
Interest rate swap derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts		26
Derivative Liability	(256)
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	96,474	17,056
U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	33,279	10,468
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	3,157	3,590
U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	2,643	24,430
Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	19,949	33,928
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	2,149	3,911
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	33,279
Total assets measured at fair value	129,753	27,524
Level 1 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities		10,468
Derivative contracts	0
Level 1 | Interest rate swap derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts		0
Level 1 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	96,474	17,056
Level 1 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	33,279	10,468
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	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	27,898
Total assets measured at fair value	28,051	65,926
Liabilities measured at fair value on recurring basis	256	240
Level 2 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities		65,859
Derivative contracts	153	(41)
Derivative Liability		240
Level 2 | Interest rate swap derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts		26
Derivative Liability	(256)
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	3,157	3,590
Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	2,643	24,430
Level 2 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	19,949	33,928
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	2,149	3,911
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration, liability	2,862	5,364	$ 6,500
Liabilities measured at fair value on recurring basis	$ (2,862)	$ (5,364)

Fair Value and Derivative Ins_4

Fair Value and Derivative Instruments - Additional Information (Details) $ in Thousands, € in Millions	Oct. 09, 2019EUR (€)	Jun. 27, 2020USD ($)	Mar. 28, 2020USD ($)	Jun. 27, 2020USD ($)	Jun. 29, 2019USD ($)	Dec. 28, 2019USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change in amount of contingent consideration		$ (3,700)	$ 1,200	$ (3,700)	$ 0
Contingent consideration, liability		$ 2,862		2,862		$ 5,364
Business Combination Contingent Consideration Arrangements, Change In Amount Of Contingent Consideration Liability, Net				$ (2,500)
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, liability | €	€ 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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
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)	$ (174)	$ (62)	$ (270)	$ (90)
Reclassification out of Accumulated Other Comprehensive Income
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)	$ (10)	$ 175	$ 12	$ 383

Fair Value and Derivative Ins_6

Fair Value and Derivative Instruments - Foreign Currency Forward Contracts (Details) - 6 months ended Jun. 27, 2020 $ in Thousands, $ in Thousands	USD ($)	TWD ($)
Derivative [Line Items]
Amount expected to be reclassified	$ 200
Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount	9,588
Buy | Euro Dollar | Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount	1,996	$ 1,897
Sell | Japanese Yen | Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount	13,766	1,475,099
Sell | Korean Won | Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount	$ 2,182	$ 2,613,516

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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
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	$ 234	$ 587	$ 349	$ 273

Fair Value and Derivative Ins_8

Fair Value and Derivative Instruments - Assets Measured at Fair Value on a Non-Recurring Basis (Details) - USD ($)	Jun. 27, 2020	Dec. 28, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value on recurring basis	$ 3,118,000	$ 5,604,000
Assets measured at fair value on non-recurring basis	157,804,000	93,450,000
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

Fair Value and Derivative Ins_9

Fair Value and Derivative Instruments - Impact of Foreign Exchange Derivattive 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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)				$ 213
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 191	$ 183	$ 372	241
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments and Tax	52	213	126
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	139	139	258	171
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	17	12	35	19
Selling, general and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 35	$ 32	$ 79	$ 51

Warranty (Details)

Warranty (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 1,942	$ 2,102
Accruals	2,116	1,648
Settlements	(1,997)	(1,923)
Balance at end of period	$ 2,061	$ 1,827

Property, Plant, and Equipmen_3

Property, Plant, and Equipment, net (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 332,202	$ 319,890
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(281,539)	(273,001)
Property Plant And Equipment Net, Excludes Construction in Progress	50,663	46,889
Construction in Progress, Gross	32,999	11,858
Property, plant and equipment, net of accumulated depreciation	83,662	58,747
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,751	0
Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	207,199	201,861
Computer Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	35,844	35,192
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	6,938	6,756
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 77,470	$ 76,081

Stockholders_ Equity and Stoc_3

Stockholders’ Equity and Stock-Based Compensation - Additional Information (Details)	6 Months Ended
	Jun. 27, 2020shares
Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	65,686

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. 27, 2020$ / sharesshares
Units
Beginning balance (in shares) | shares	3,069,000
Awards granted (in shares) | shares	65,686
Awards vested (in shares) | shares	(465,440)
Awards canceled (in shares) | shares	(29,552)
Ending balance (in shares) | shares	2,639,694
Weighted Average Grant Date Fair Value
Beginning Balance (in dollars per share) | $ / shares	$ 14.30
Awards granted (in dollars per share) | $ / shares	23.92
Awards vested (in dollars per share) | $ / shares	14.84
Awards canceled (in dollars per share) | $ / shares	14.23
Ending Balance (in dollars per share) | $ / shares	$ 14.45

Stockholders_ Equity and Stoc_5

Stockholders’ Equity and Stock-Based Compensation - Stock Option Activity (Details) - Equity Incentive Plan $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 27, 2020USD ($)$ / sharesshares
Options Outstanding
Outstanding, beginning of period (In shares) | shares	361,769
Options exercised (In shares) | shares	(105,769)
Outstanding, end of period (In shares) | shares	256,000
Exercisable (In shares) | shares	256,000
Weighted Average Exercise Price
Outstanding, beginning of period (In dollars per share) | $ / shares	$ 8.35
Options exercised (In dollars per share) | $ / shares	8.21
Outstanding, end of period (In dollars per share) | $ / shares	8.41
Exercisable (In dollars per share) | $ / shares	$ 8.41
Additional Disclosures
Outstanding, weighted average remaining contractual life	1 year 7 months 17 days
Exercisable, weighted average remaining contractual life	1 year 7 months 17 days
Outstanding, aggregate intrinsic value | $	$ 4,816,740
Exercisable, aggregate intrinsic value | $	$ 4,816,740
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number | shares	256,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price | $ / shares	$ 8.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	1 year 7 months 17 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value | $	$ 4,816,740

Stockholders_ Equity and Stoc_6

Stockholders’ Equity and Stock-Based Compensation - ESPP Activity (Details) - Employee stock purchase plan	6 Months Ended
	Jun. 27, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under ESPP (In shares) | shares	311,591
Weighted average per share purchase price (in dollars per share)	$ 13.05
Weighted average per share discount from the fair value of our common stock on the date of issuance (in dollars per share)	$ 12.26

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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 5,642	$ 5,289	$ 11,265	$ 10,584
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	901	964	1,838	1,914
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,389	1,582	2,828	3,101
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 3,352	$ 2,743	$ 6,599	$ 5,569

Stockholders_ Equity and Stoc_8

Stockholders’ Equity and Stock-Based Compensation - Unrecognized Compensation Costs (Details) $ in Thousands	6 Months Ended
	Jun. 27, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense	$ 21,925
Average expected recognition period	1 year 7 months 9 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 17,242
Average expected recognition period	1 year 7 months 9 days
Performance restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 4,518
Average expected recognition period	1 year 7 months 20 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 165
Average expected recognition period	1 month 6 days

Net Income per Share (Details)

Net Income per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Earnings Per Share [Abstract]
Weighted-average shares used in computing basic net income (loss) per share (In shares)	76,275	74,478	76,140	74,483
Add potentially dilutive securities (In shares)	2,586	1,711	2,570	1,578
Weighted-average shares used in computing diluted net income per share (In shares)	78,861	76,189	78,710	76,061
Anti-dilutive securities (In shares)	0	263	13	252

Leases - Narrative (Details)

Leases - Narrative (Details)	Jun. 27, 2020
Lessee, Lease, Description [Line Items]
Operating lease, renewal term	20 years
Operating lease, weighted average remaining lease term	7 years
Operating lease, weighted average discount rate	4.70%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	15 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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Leases [Abstract]
Operating lease expense	$ 1,794	$ 1,734	$ 3,719	$ 3,479
Short-term lease expense	27	31	66	48
Variable lease expense	399	249	782	668
Lease, Cost	$ 2,220	$ 2,014	$ 4,567	$ 4,195

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Payments Under Leases (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Leases [Abstract]
Remainder of 2020	$ 3,532
2020	6,275
2021	5,084
2022	4,446
2023	4,261
Thereafter	16,150
Lessee, Operating Lease, Liability, Payments, Due	39,748
Less: interest	(6,764)
Operating Lease, Liability, Total	32,984
Less: current portion	(6,168)	$ (6,551)
Long-term operating lease liabilities	$ 26,816	$ 29,088

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 26, 2020	Jun. 27, 2020	Dec. 25, 2022	Dec. 25, 2021	Dec. 28, 2019
Disaggregation of Revenue [Line Items]
Performance obligations		$ 3.9
Contract assets		4.3			$ 0.9
Contract liabilities		14.7			$ 10.8
Revenue recognized included in contracts		$ 7.2
Forecast
Disaggregation of Revenue [Line Items]
Expected to be recognized	55.60%		14.80%	29.60%

Operating Segments and Enterp_3

Operating Segments and Enterprise-Wide Information - Additional Information (Details)	6 Months Ended
	Jun. 27, 2020segment
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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Segment Reporting Information [Line Items]
Revenues	$ 157,824	$ 138,018	$ 318,577	$ 270,231
Gross profit	$ 66,167	$ 55,352	$ 133,557	$ 107,873
Gross margin	41.90%	40.10%	41.90%	39.90%
Probe Cards
Segment Reporting Information [Line Items]
Revenues	$ 133,784	$ 113,637	$ 268,499	$ 221,740
Systems
Segment Reporting Information [Line Items]
Revenues	24,040	24,381	50,078	48,491
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Gross profit	$ (6,075)	$ (5,812)	$ (12,762)	$ (11,600)
Gross margin	0.00%	0.00%	0.00%	0.00%
Operating Segments | Probe Cards
Segment Reporting Information [Line Items]
Revenues	$ 133,784	$ 113,637	$ 268,499	$ 221,740
Gross profit	$ 61,523	$ 48,492	$ 122,266	$ 93,785
Gross margin	46.00%	42.70%	45.50%	42.30%
Operating Segments | Systems
Segment Reporting Information [Line Items]
Revenues	$ 24,040	$ 24,381	$ 50,078	$ 48,491
Gross profit	$ 10,719	$ 12,672	$ 24,053	$ 25,688
Gross margin	44.60%	52.00%	48.00%	53.00%

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. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 157,824	$ 138,018	$ 318,577	$ 270,231
Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	133,784	113,637	268,499	221,740
Systems
Disaggregation of Revenue [Line Items]
Revenues	24,040	24,381	50,078	48,491
China
Disaggregation of Revenue [Line Items]
Revenues	48,758	20,355	92,400	42,198
China | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	45,625	16,304	82,905	34,455
China | Systems
Disaggregation of Revenue [Line Items]
Revenues	3,133	4,051	9,495	7,743
Taiwan
Disaggregation of Revenue [Line Items]
Revenues	33,171	14,872	29,201	54,894
Taiwan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	29,806	12,826	27,941	52,378
Taiwan | Systems
Disaggregation of Revenue [Line Items]
Revenues	3,365	2,046	1,260	2,516
United States
Disaggregation of Revenue [Line Items]
Revenues	28,121	38,369	60,037	72,632
United States | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	22,368	32,072	47,979	59,727
United States | Systems
Disaggregation of Revenue [Line Items]
Revenues	5,753	6,297	12,058	12,905
South Korea
Disaggregation of Revenue [Line Items]
Revenues	15,113	28,171	64,951	37,259
South Korea | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	14,249	27,360	60,245	34,083
South Korea | Systems
Disaggregation of Revenue [Line Items]
Revenues	864	811	4,706	3,176
Europe
Disaggregation of Revenue [Line Items]
Revenues	14,132	10,648	35,175	20,141
Europe | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	8,767	4,474	24,977	9,847
Europe | Systems
Disaggregation of Revenue [Line Items]
Revenues	5,365	6,174	10,198	10,294
Japan
Disaggregation of Revenue [Line Items]
Revenues	10,059	16,093	14,363	10,946
Japan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	6,679	12,867	8,802	9,052
Japan | Systems
Disaggregation of Revenue [Line Items]
Revenues	3,380	3,226	5,561	1,894
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	6,500	7,683	18,429	26,525
Asia-Pacific | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	4,347	6,262	12,214	18,167
Asia-Pacific | Systems
Disaggregation of Revenue [Line Items]
Revenues	2,153	1,421	6,215	8,358
Rest of the world
Disaggregation of Revenue [Line Items]
Revenues	1,970	1,827	4,021	5,636
Rest of the world | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	1,943	1,472	3,436	4,031
Rest of the world | Systems
Disaggregation of Revenue [Line Items]
Revenues	27	355	585	1,605
Products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues	155,756	136,367	314,683	267,000
Products transferred at a point in time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	133,208	113,028	267,277	220,519
Products transferred at a point in time | Systems
Disaggregation of Revenue [Line Items]
Revenues	22,548	23,339	47,406	46,481
Services transferred over time
Disaggregation of Revenue [Line Items]
Revenues	2,068	1,651	3,894	3,231
Services transferred over time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	576	609	1,222	1,221
Services transferred over time | Systems
Disaggregation of Revenue [Line Items]
Revenues	1,492	1,042	2,672	2,010
Foundry & Logic
Disaggregation of Revenue [Line Items]
Revenues	109,347	73,442	215,092	145,022
Foundry & Logic | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	109,347	73,442	215,092	145,022
Foundry & Logic | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
DRAM
Disaggregation of Revenue [Line Items]
Revenues	19,052	36,044	43,748	64,930
DRAM | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	19,052	36,044	43,748	64,930
DRAM | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Flash
Disaggregation of Revenue [Line Items]
Revenues	5,385	4,151	9,659	11,788
Flash | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	5,385	4,151	9,659	11,788
Flash | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Systems
Disaggregation of Revenue [Line Items]
Revenues	24,040	24,381	50,078	48,491
Systems | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Systems | Systems
Disaggregation of Revenue [Line Items]
Revenues	$ 24,040	$ 24,381	$ 50,078	$ 48,491

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event [Member] $ in Millions	Jul. 30, 2020USD ($)
Subsequent Event [Line Items]
Consideration transferred	$ 35
Business Combination, Reason for Business Combination	This acquisition brings important enabling technologies and capabilities for designing and manufacturing advanced memory 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.

Uncategorized Items - form-2020

Label	Element	Value
Common Stock [Member]
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	$ 1,000