<SEC-DOCUMENT>0000056978-19-000055.txt : 20190514
<SEC-HEADER>0000056978-19-000055.hdr.sgml : 20190514
<ACCEPTANCE-DATETIME>20190514135257
ACCESSION NUMBER:		0000056978-19-000055
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190510
FILED AS OF DATE:		20190514
DATE AS OF CHANGE:		20190514

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:		19821944

	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:			0928

	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_155785636336294.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-05-10</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>Senior Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11616</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>69401</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>2019-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11616</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>11616.0</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 May 10, 2016 had its performance results certified, and then shares vested, on May 10, 2019 at 183% 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>2019-05-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
