<SEC-DOCUMENT>0000056978-20-000134.txt : 20201110
<SEC-HEADER>0000056978-20-000134.hdr.sgml : 20201110
<ACCEPTANCE-DATETIME>20201110093156
ACCESSION NUMBER:		0000056978-20-000134
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201107
FILED AS OF DATE:		20201110
DATE AS OF CHANGE:		20201110

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Chong Chan Pin
		CENTRAL INDEX KEY:			0001692400

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-00121
		FILM NUMBER:		201299830

	MAIL ADDRESS:	
		STREET 1:		23A SERANGOON NORTH AVENUE 5
		STREET 2:		#01-01
		CITY:			SINGAPORE
		STATE:			U0
		ZIP:			554369

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KULICKE & SOFFA INDUSTRIES INC
		CENTRAL INDEX KEY:			0000056978
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				231498399
		STATE OF INCORPORATION:			PA
		FISCAL YEAR END:			1003

	BUSINESS ADDRESS:	
		STREET 1:		23A SERANGOON NORTH AVENUE 5, #01-01
		CITY:			SINGAPORE
		STATE:			U0
		ZIP:			554369
		BUSINESS PHONE:		2157846000

	MAIL ADDRESS:	
		STREET 1:		23A SERANGOON NORTH AVENUE 5, #01-01
		CITY:			SINGAPORE
		STATE:			U0
		ZIP:			554369
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_160501870230966.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-11-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000056978</issuerCik>
        <issuerName>KULICKE &amp; SOFFA INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>KLIC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001692400</rptOwnerCik>
            <rptOwnerName>Chong Chan Pin</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>23A SERANGOON NORTH AVENUE 5 #01-01</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SINGAPORE</rptOwnerCity>
            <rptOwnerState>U0</rptOwnerState>
            <rptOwnerZipCode>554369</rptOwnerZipCode>
            <rptOwnerStateDescription>SINGAPORE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5952</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>98783</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-11-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5952</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5952.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Performance Share Units (PSUs) awarded November 7, 2017 had its performance results certified, and then shares vested, on November 7, 2020 at 95% achievement based on total shareholder return (TSR) relative to a peer group.  The peer group consisted of the companies of the GICS 45301020 (Semiconductors) not including companies traded on the Pink Sheets LLC Exchange as of the beginning of Performance Period with relative TSR measured over a three year period.  Each PSU is convertible into one share of Kulicke and Soffa Industries Inc. common stock.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Susan L. Waters, Attorney-in-Fact for Chan Pin Chong</signatureName>
        <signatureDate>2020-11-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
