BGA焊點(diǎn)中的金脆化

深圳市福英達(dá)工業(yè)技術(shù)有限公司/一站式錫膏解決方案供應(yīng)商GoldEmbrittlementinBGASolderJointsGoldembrittlementisasolderingdefectthatreferstosolderjointsthatcontaintoomuchintermetalliccompound(IMC),resultinginincreasedbrittlenessandreducedreliability.GoldembrittlementmainlyoccursintwolocationsofBGAsolderjoints,namelybetweentheBGAbodyandthesolderballandbetweenthesolderpasteandtheimmersionplatepads.TheBGAsolderjointgoldembrittlementcanbesubdividedintotwocategories,oneisthegoldembrittlementcausedbyinsufficientheat,andtheotheristhegoldembrittlementcausedbyexcessivegoldcontent.GoldembrittlementcausedbyinsufficientheatInsufficientheatinthePCBAsolderingprocess,themetalofthePCBimmersionlayerwillentertheliquidsolder,formingAuSn4build-upinthevicinityoftheintermetalliccompounds(IMC)ofthesolderjoints,resultingingoldembrittlementofthesolderjoints.ThisgoldembrittlementproblemcanbeimprovedbyadjustingthePCBAsolderingprocessconditions,suchasincreasingthesolderingtemperatureandprolongingthesolderingtime,toensurethatthemetalinthesolderjointcanbefullymeltedanddiffused.GoldembrittlementcausedbyexcessivegoldcontentAnothertypeofgoldembrittlementproblemiscausedbytheBGAsolderjointswithinthegoldcontentexceedsacertainpercentage.Whenthegoldcontentinthesolderjointexceeds3%wtoreven5%wtormore,therateofintermetalliccompoundformationincreases,resultingingoldembrittlementofthesolderjoint.Thisgoldembrittlementcannotbesolvedbyadjustingthereflowsolderingtemperatureprofile,butrequiresothermeasures.Inordertoreducethegoldcontentinthesolderjoints,youcancontrolthethicknessofthegoldlayerorincreasetheamountofsolder,sothatthegoldcontentinthesolderjointstomaintaintheappropriaterange.AsfarasthePCBAprocessisconcerned,thelimitedthicknessofchemicalnickelgolddoesnotleadtoexcessivegoldcontentwithinthesolderjoints,moreoftenthannot,thegoldlayerdiffusionisincompleteresultingingoldembrittlement.Ifthegoldlayerdiffusionisincomplete,evenifthethicknessofelectrolessnickelgoldisappropriate,theremaystillbegoldembrittlementproblems.Therefore,forthePCBAprocess,toensurethatthediffusionofthegoldlayerisuniformandcompleteisalsocritical.Inconclusion,BGAsolderjointgoldembrittlementisasolderingdefectthatneedstobetakenseriously,andithasanon-negligibleimpactonthereliabilityandperformanceofelectronicproducts.Wemustrecognisethatgoldembrittlementinvolvestwomainaspects:insufficientheatandexcessivegoldcontent.Solvingtheseproblemsrequirescomprehensivemeasures,includingoptimisingweldingprocessparameters,controllingthethicknessofthegoldlayerandproperlyadjustingtheweldingtemperatureandtime.Inactualproduction,manufacturersshouldstrictlycontrolthesolderingprocesstoensurethatthesolderingtemperatureandtimecanmakethesolderjointswithinthemetalfullymeltedanddiffusedtoavoidtheproductionofgoldembrittlement.Inaddition,fortheBGApackagedesign,reasonablesettingofthelayoutandstructureofthesolderjointstoavoidstressconcentrationonthesolderjoints,isalsothekeytoreducegoldembrittlement.Atthesametime,thescientificandreasonableselectionofPCBAmaterialsandprocesses,controlthediffusionofgoldlayeruniformityandintegrity,willbeanimportantdirectiontosolvetheproblemofgoldembrittlement.Forthesolderjointswithinthegoldcontentistoohig