ASTM_F_459_-_13.pdf

Designation:F45913Standard Test Methods forMeasuring Pull Strength of Microelectronic Wire Bonds1This standard is issued under the fixed designation F459;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 These test methods cover tests to determine the pullstrength of a series of wire bonds.Instructions are provided tomodify the methods for use as a referee method.The methodscan be used for wire bonds made with wire having a diameterof from 0.0007 to 0.003 in.(18 to 76 m).NOTE1Common usage at the present time considers the term“wirebond”to include the entire interconnection:both welds and the interven-ing wire span.1.2 These test methods can be used only when the loopheight of the wire bond is large enough to allow a suitable hookfor pulling(see Fig.1)to be placed under the wire.1.3 The precision of these methods has been evaluated foraluminum ultra-sonic wedge bonds;however,these methodscan be used for gold and copper wedge or ball bonds.21.4 These methods are destructive.They are appropriate foruse in process development or,with a proper sampling plan,forprocess control or quality assurance.1.5 A nondestructive procedure is described in PracticeF458.1.6 The values in SI units are to be regarded as standard.1.7 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3F458 Practice for Nondestructive Pull Testing of Wire Bonds3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 For the purposes of these test methods the followingfailure points are defined:3.1.2 bond-wire junction failurea rupture in the wirewithin two wire diameters of the bond and in which more than25%of the bonded area is left on the pad after the pull test hasbeen applied.3.1.3 weld interface failurea rupture in which less than25%of the bonded area is left on the pad after the pull test hasbeen applied.See pad lifting in 6.6.3.1.4 wire span failurea rupture in the wire other than(1)at a point within two wire diameters of either bond,or(2)at thepoint at which the hook contacted the wire.4.Summary of Test Methods4.1 The microelectronic device with the wire bond to betested is held firmly in an appropriate fixture.A hook ispositioned under the wire midway between the two bonds.Thehook is then raised until the wire bond breaks.The forceapplied to the hook in order to cause failure of the wire bondis recorded.The point of failure is observed and recorded.Inthe referee method,the force in the wire on breaking iscalculated.5.Significance and Use5.1 Failure of microelectronic devices is often due to failureof an interconnection bond.A common type of interconnectionbond is a wire bond.These methods can assist in maintaining1These test methods are under the jurisdiction of ASTM Committee F01 onElectronics and are the direct responsibility of Subcommittee F01.03 on MetallicMaterials,Wire Bonding,and Flip Chip.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 1976 as F459 76 T.Last previous edition approved in 2006 asF459 06.DOI:10.1520/F0459-13.2Harman,G.G.,”Microelectronic Ultrasonic Bonding,”NBS Special Publica-tion 400-2,pp.94-95 and“Wire Bonding in Microelectronics,”Third Edition,McGraw Hill,2010.Also Microelectronics Reliability 51(2011),Special Issue onCopper bonding.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 control of the process of making wire bonds.They can be usedto distinguish between weak,nonadherent wire bonds andacceptably strong wire bonds.The methods are destructive.5.2 These test methods are appropriate for on-line use forprocess control,for purchase specifications,and for research insupport of improved yield or reliability.The referee methodshould be used for quantitative comparison of pull strengths ofwire bonds.6.Interferences6.1 Failure to center the hook along the loop between thetwo bonds or pulling in a direction not lying in the planecontaining the undisturbed loop may invalidate the test since anunbalanced distribution of forces between the two bonds mayresult.6.2 Slippage of the hook along the wire span during pullingmay invalidate the test because an unbalanced distribution offorces between