SMT

StartSMTdefect&countermeasure-levelISMT缺陷及防范措施2•Objective/目的•SMTDefectsIdentification/SMT缺陷确定•Failureanalysismethodandprocedure/缺陷分析的方法及流程•SMTDefectsandCountermeasure/SMT缺陷及防范措施Tombstoning/立碑SolderBridge/桥联ComponentDamaged(Nicks,Cracks,orStressFractures)/元件损坏Misalignment/偏位ComponentLeadLifted元件引脚翘高SolderBall/锡珠Non-Wetting,Dewetting/虚焊，半润湿ColdSolder/冷焊DisturbedSolder/焊锡紊乱NoSolder/无锡InsufficientSolder/少锡ExcessSolder/多锡WrongOrientation/Polarity/反向,极性反SolderHole/锡洞SolderProjections/锡尖Others/其它SlideContents3Knowthecommondefect了解常见缺陷类型Analyzethepossiblecause分析可能的原因Countermeasureforthedefects基于以上原因采取的对策Objectives/目的4SMTDefectsIdentification/SMT缺陷确定IdentifytheSMTdefectsaccordingtoIPC-A-610(Rev:D)根据IPC-A-610(Rev:D)确定缺陷．Thisstandardisacollectionofvisualqualityacceptabilityrequirementsforelectronicassemblies.IPC-A-610是关于电子组装外观质量验收条件要求的文件．5ComponentPlacement15%ReflowsolderandCleaning15.3%SolderPasteScreening64.2%IncomingComponent5.7%MajorContributortoDefects/缺陷的主要分布Source:MPM’sAuser’sguidetomorepreciseSMTprinting6FailureAnalysis缺陷分析FailureAnalysis/缺陷分析7WheretostartyourInvestigation-“Threesimplequestions”三个简单问题8TwoAvenuesofInvestigation/两种调查途径9“HistoricalResearch”历史记录调查10Tests&Investigations/测试,调查11FindTheRootCause/找到问题的根本原因12“Fish-bone”Chart/鱼骨图Equipment设备Methods方法Materials物料Environment环境Man人Humidity湿度Temperature温度Training培训Authority认证Attitude态度Factorsresultinthedefects.Themanyinteractionsshowthattheymustberelatedasasystemandbere-evaluatedwhenchangesoccurs.13EffectiveUseofBackgroundInformation/有效利用信息14TheDMAICProcess/DMAIC流程15SMTDefectsandCountermeasureSMT缺陷及防范措施SMTDefectsandCountermeasure/SMT缺陷及防范措施16•Chipcomponentsstandingonaterminalend(tombstoning).片式元件末端翘起（墓碑）Tombstoning/立碑17Countermeasure/对策Mechanism:Surfacetensionincomponentterminalisuneveninreflow.原理:在回流过程中零件两末端的表面张力不均衡.1.Componentterminalheatdistributedunevenly零件两末端受热分布不均衡.Insufficientsoaktime:Reflowprofileoptimization.保温区时间太短:优化回流曲线参数.2.PCBPaddesignissue(thepadsdistanceistoobig):DFM(DesignforManufacturability)toimprovePCBpaddesign.PCB焊盘设计问题(焊盘间距太大):DFM以改善PCB焊盘设计.Tombstoning/立碑18Countermeasure/对策3.Componentterminaloxidizationorcontamination:SolderabilitytestifnecessaryandRTVthedefectmaterial.元件末端氧化或者受污染:根据情况做可焊性实验并且退还缺陷物料.4.Printingmisalignment:adjustprintingmachineparameters.丝印偏位:校正丝印机的参数.5.Placementmisalignment:OptimizetheP&Pmachineparameters.贴片偏位:优化贴片机的参数.6.Stencilaperturedesignissue:studyandimprovetheaperturedesign.钢网开孔的设计问题:研究并且改善开孔设计.Tombstoning/立碑19•Asolderconnectionacrossconductorsthatwasjoined.焊锡在导体间非正常连接.•Solderhasbridgedtoadjacentnon-commonconductororcomponent.焊锡桥连到相邻的非导体或元件.SolderBridge/桥联20Countermeasure/对策1.Screenprintingissue/丝印问题:a)PasteheightoutofUCL:Adjusttheprintertocontrolthepasteheight.锡膏高度超出控制上线:校正丝印机,控制锡膏高度.b)Pasteprintingmisalignmentorbridging:Finetuneprintingmachine./锡膏印刷偏位或者桥联:优化丝印机.c)Icicleprinting:Finetuneprintingmachineorchangetolowerviscositypaste.丝印拉尖:优化丝印机或者使用低粘性的锡膏.d)Solderpastecollapse:changetohigherviscositypaste./锡膏塌陷:使用高粘性的锡膏.e)Nonstandardstencilapertureopening:Studyandimprovetheaperture./不标准的钢网开孔:研究并改善开孔.Icicleprinting丝印拉尖Pastecollapse锡膏塌陷Bridging桥联Misalignment印刷偏位SolderBridge/桥联21Countermeasure/对策2.Pick&Placement/贴片a)Componentplacingmisalignment:FinetunetheP&Pmachine.元件贴片偏位:优化贴片机的参数.b)Highpressureforplacement:reducepressuretopropervalue.贴片压力过大:减少压力到适当的参数.3.Wavesoldering/波峰焊a)Lowconveyorramp:Raisetheconveyorrampperactualstatus.传送带角度过小:根据实际情况加大传送带角度b)Lessfluxonboard:Increasethefluxsprayvolumeonboardbeforegoingthroughwavesoldering.板上的助焊剂较少:波峰焊接之前加大助焊剂的喷射量SolderBridge/桥联22ComponentDamaged(Nicks,Cracks,orStressFractures)/元件损坏Nicks,cracks,orstressfractures.缺口，裂纹，压痕23ComponentDamaged(Nicks,Cracks,orStressFractures)/元件损坏24Misalignment/偏位25Countermeasure/对策1.P&Pmachinefunctionunstable:FinetunetheP&Pmachine.贴片机性能不稳定:优化贴片机性能参数.a)FinetuneX,Ydata/调整X,Y坐标b)Optimizepickandplacementparameters./校正吸料和贴片的参数.2.Componentterminationoxidization:Solderabilitytestifnecessary.Purgethefailedmaterial/元件末端氧化:可焊性实验,清除不合格的来料.3.Operatortouchthecomponentpriortoreflow:Standardizetheoperatorhandling(documentcontrol)/在回流炉前目检操作员碰到贴片元件:标准化操作员操作(文件控制)Misalignment/偏位26ComponentLeadLifted元件引脚翘高Oneleadorseriesofleadsoncomponentisoutofalignmentandfailstomakecontactwiththeland.元件一个或多个引脚变形不能与焊盘正常接触．27ComponentLeadLifted/元件引脚翘高Countermeasure/对策1.Componentleadbentbeforeplacement:Sortthedefectivepartandreturnittovendor.贴片前元件引脚变形:挑选出缺陷元件,退回供应商．2.Manualplacementtheloosepart:Inspectthepartbeforepassittoreflow.手放散料:回流前目检．28SolderBall/锡珠•Solderballsarespheresofsolderthatremainafterthesolderingprocess.Solderballsviolateminimumelectricalclearance.焊锡球是焊接后形成的呈球状焊锡.•Solderfinesaretypicallysmallballsoftheoriginalsolderpastemetalscreensizethathavesplatteredaroundtheconnectionduringthereflowprocess.焊锡残渣是在回流中形成的小的球状或不规则状焊锡球.29SolderBall/锡珠30SolderBall/锡珠Countermeasure/对策1.StencilAperturedonotfocustopad:improvestencilapertureopening.钢网开孔没有对准焊盘中心:改善钢网开孔.2.Printingmisalignment:Finetuneprintmachine.丝印偏位:调整丝印机状态.3.Excesspaste:Cpkcontrol.多锡:Cpk控制.4.DampPCB:BakethePCBbefo