Package-related Failure Mechanisms and Attributes 可靠性技术 可靠性设计 07年7月1日 编辑 bluech 取消关注 关注 私信 文章一篇 给TA打赏 共{{data.count}}人 人已打赏
adminM可靠性网管理员 lv6lv6 07年7月1日 [b]Package-relatedFailureMechanismsandAttributes[/b] ———-BallLifting Balllifting,isthedetachmentofaballbondfromthebondpadofasemiconductordevice. Seeseparatearticleonballlifting. BondShorting BondShortingisthepresenceofanunintendedelectricalconnectionbetweentwobonds.Theelectricalconnectionmaybeintheformofbondstouchingeachother,orstrayconductivematerialsbridgingonebondtoanother.Bondplacementproblemsinvolvingadjacentwedgebondswithlongtailsinadiewithtightly-packedbondpadsarethemostcommonformoftouchingbonds. Designrulesforbondpadsizeandspacing,bondsize,bondposition,andbonddeformationcaneasilypreventtouchingbonds.Dieattachmaterialthataccidentallyfallsordripsonthediesurface,orreachitinwhateverway,canbridgeonebondtoanother.Straywiresthatsomehowgetintohermeticpackagescanalsobridgeonebondtoanother.Eutecticflakesorballsfromhighlyoxidizedeutecticdieattachmaterialcangetlooseinsidethepackageandlikewiseactasbridgesbetweenbonds.Aluminumsqueeze-outsaroundthewedgebondscanalsogetlooseandshortbonds. BrandFailureAttributes Poormarkabilityistheconditionwhereinthepackageisdifficultorimpossibletomarkorbrandcorrectlyand/orthemarkorbrandonthepackageexhibitsinsufficientpermanence.Inkmarkabilityproblemsareoftenduetotheinabilityoftheinktoadheretothesurfaceofthepackage.Lasermarkabilityproblemsareoftenduetoimproperbrandingequipmentset-up,butmaysometimesbeduetotexturalproblemsonthesurfaceofthepackageaswell. Pooradhesionofinkmarksorbrandsonthepackageisusuallycausedbythepresenceofathinfilmorlayerofforeignmaterialonthepackagesurface.Forinstance,packageswithexcessiveamountsofmoldreleaseagentontheirsurfacesarelikelytoexhibitpoormarkability.Itmayalsobeduetotheuseofanincorrect,incompatible,orexpiredink. Poorlasermarkabilityisusuallycausedbywronglaserbrandingsettings.Packageswithtexturalproblemsordefectsmaylikewiseexhibitpoorcontrastafterlasermarking.Forexample,reworkedpackagesthathaveundergonesandblastinggenerallyexhibitillegiblemarks. Contamination,External Externalcontaminationisthepresenceofaforeignmaterial,whetherattachedorunattached,anywhereontheexternalportionsofthepackageandleads.Thecriteriaforrejectingexternalcontaminationdependsonitslocation,extent,andcomposition.Somecontaminantsarerejectedbecauseitresultsincosmeticfailure,whileothersarerejectedbecauseofthereliabilityriskinvolved,mainlywithregardtoleadcsolderabilityissues,aswellaselectricalleakabetweenpins
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[b]Package-relatedFailureMechanismsandAttributes[/b]
———-BallLifting
Balllifting,isthedetachmentofaballbondfromthebondpadofasemiconductordevice.
Seeseparatearticleonballlifting.
BondShorting
BondShortingisthepresenceofanunintendedelectricalconnectionbetweentwobonds.Theelectricalconnectionmaybeintheformofbondstouchingeachother,orstrayconductivematerialsbridgingonebondtoanother.Bondplacementproblemsinvolvingadjacentwedgebondswithlongtailsinadiewithtightly-packedbondpadsarethemostcommonformoftouchingbonds.
Designrulesforbondpadsizeandspacing,bondsize,bondposition,andbonddeformationcaneasilypreventtouchingbonds.Dieattachmaterialthataccidentallyfallsordripsonthediesurface,orreachitinwhateverway,canbridgeonebondtoanother.Straywiresthatsomehowgetintohermeticpackagescanalsobridgeonebondtoanother.Eutecticflakesorballsfromhighlyoxidizedeutecticdieattachmaterialcangetlooseinsidethepackageandlikewiseactasbridgesbetweenbonds.Aluminumsqueeze-outsaroundthewedgebondscanalsogetlooseandshortbonds.
BrandFailureAttributes
Poormarkabilityistheconditionwhereinthepackageisdifficultorimpossibletomarkorbrandcorrectlyand/orthemarkorbrandonthepackageexhibitsinsufficientpermanence.Inkmarkabilityproblemsareoftenduetotheinabilityoftheinktoadheretothesurfaceofthepackage.Lasermarkabilityproblemsareoftenduetoimproperbrandingequipmentset-up,butmaysometimesbeduetotexturalproblemsonthesurfaceofthepackageaswell.
Pooradhesionofinkmarksorbrandsonthepackageisusuallycausedbythepresenceofathinfilmorlayerofforeignmaterialonthepackagesurface.Forinstance,packageswithexcessiveamountsofmoldreleaseagentontheirsurfacesarelikelytoexhibitpoormarkability.Itmayalsobeduetotheuseofanincorrect,incompatible,orexpiredink.
Poorlasermarkabilityisusuallycausedbywronglaserbrandingsettings.Packageswithtexturalproblemsordefectsmaylikewiseexhibitpoorcontrastafterlasermarking.Forexample,reworkedpackagesthathaveundergonesandblastinggenerallyexhibitillegiblemarks.
Contamination,External
Externalcontaminationisthepresenceofaforeignmaterial,whetherattachedorunattached,anywhereontheexternalportionsofthepackageandleads.Thecriteriaforrejectingexternalcontaminationdependsonitslocation,extent,andcomposition.Somecontaminantsarerejectedbecauseitresultsincosmeticfailure,whileothersarerejectedbecauseofthereliabilityriskinvolved,mainlywithregardtoleadcsolderabilityissues,aswellaselectricalleakabetweenpins