SMT缺陷及防范措施.ppt

2020 4 17 1 SMTdefectsandcountermeasureSMT缺陷及防范措施 2020 4 17 2 IdentifySMTdefects 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 2020 4 17 3 Majorcontributortodefects缺陷的主要分布 Source MPM sAuser sguidetomorePreciseSMTprinting 2020 4 17 4 Knowthecommondefect了解常见缺陷类型Analysizethepossiblecause分析可能的原因Countermeasureforthedefects基于以上原因采取的对策 LearningObjectives学习目的 2020 4 17 5 Chipcomponentsstandingonaterminalend tombstoning 片式元件末端翘起 墓碑 Tombstoning 立碑 2020 4 17 6 Countermeasure 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 improvePCBpaddesign PCB焊盘设计问题 焊盘间距太大 改善PCB焊盘设计 Tombstoning 立碑 2020 4 17 7 Countermeasure 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 2020 4 17 8 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 2020 4 17 9 Countermeasure 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 Solderbridge 桥联 Icicleprinting丝印拉尖 Pastecollapse锡膏塌陷 Bridging桥联 Misalignment印刷偏位 2020 4 17 10 Countermeasure 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 2020 4 17 11 Componentdamaged Nicks cracks orstressfractures 元件损坏 Nicks cracks orstressfractures 缺口 裂纹 压痕 2020 4 17 12 Countermeasure 对策1 Rawmaterialdamaged purgethebatchmaterial 来料损坏 清除这批来料 2 DamagedduringSMTprocess Fixtureormachinetouchit Investigateandtakecorrectiveactionsfornonstandardoperation 在SMT流程中损坏 夹具和设备接触 调查分析并且对不规范的操作作出矫正行动 3 Fastcoolingrateonreflowprocess Controlthecoolingratetobelow4degreepersecond 在回流过程中冷却速率过快 控制冷却速度使斜率保持在每秒4度以下 Typicalreflowprofile 回流曲线典例 Componentdamaged Nicks cracks orstressfractures 元件损坏 2020 4 17 13 Misalignment偏位 2020 4 17 14 Countermeasure 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 4 Airflowrateinthereflowovenissohighthatthecomponentsaremoved 回流炉内空气流量太高以致吹偏了元件 Misalignment偏位 2020 4 17 15 Componentleadlifted元件引脚翘高 Oneleadorseriesofleadsoncomponentisoutofalign mentandfailstomakecontactwiththeland 元件一个或多个引脚变形不能与焊盘正常接触 2020 4 17 16 Componentleadlifted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 2020 4 17 17 Solderball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 2020 4 17 18 Solderball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 BakethePCBbeforeloadingittoSMT PCB焊盘受潮 SMT组装流程之前烘烤PCB 6 Stencilpolluted cleanthestencil 钢网脏污 清洗钢网 7 Profilerampupistoofast Optimizereflowprofile 回流曲线升温速度过快 优化回流曲线 8 Pasteoxidized exchangewithfreshsolderpaste 锡膏氧化 更换新锡膏 9 Chipwaveorsolderwaveheightistoohighcausedexcesssoldertotopside adjustthewavesolderingheighttoproperlevel wavesolder 波峰高度设置的太高致使多余的焊锡到顶面 校正波峰焊设置到适当的高度 波峰焊接 2020 4 17 19 Non Wetting Dewetting 虚焊 半润湿 Solderhasnotwettedtothelandorterminationwheresolderisrequired 虚焊 需要焊接的引脚焊盘不润湿 Soldercoveragedoesnomeetrequirementsfortheterminationtype Dewettingasaconditionresultswhenmoltensoldercoatsasurfaceandthenrecedestoleaveirregularly shapedmoundsofsolderthatareseparatedbyareasthatarecoveredwithathinfilmofsolderandwiththebasismetalorsurfacefinishnotexposed 半润湿 熔化的焊锡浸润表面后收缩 留下一焊锡薄层覆盖部分区域 焊锡形状不规则 2020 4 17 20 Non Wetting Dewetting 虚焊 半润湿 1 Poorsolderabilityofcomponentorpad 元件或焊盘可焊性太低Rootcause a OlddatecomponentorPCB 陈旧元件或PCB板b ContaminationoroxidationoncomponentorPCB 元件或焊盘污染或氧化Action Purgethematerialforfurtherdisposition 清除来料2 Thepasteoutofitslifetime 锡膏超出有效期Scrapthelotpasteandreplaceitwithfreshone报废有问题的锡膏更换新锡膏 2020 4 17 21 Coldsolder 冷焊 Incompletereflowofsolderpaste 焊锡回流不完全 2020 4 17 22 Coldsolder 冷焊 Countermeasure 对策1 Peaktemperatureistooloworreflowtime dwelltime isnotenough Re setuptheprofiletofulfillthepastespecorcustomerprovidedspec requirement 回流峰值温度太低或者回流时间不够 重设温度曲线图 Typicalreflowprofile 典型的回流曲线 2020 4 17 23 Time时间 Temp 温度 230 C 250 C tc1 smallSMD tc1 mediumSMD tc3 largeSMD 20 C 20 C Peak 230 250 C Coldsolder 冷焊 2020 4 17 24 Coldsolder 冷焊 Countermeasure 对策2 Thecomponentinsomelocationcoveredwithreflowpallet Peaktemperatureistooloworreflowtime dwelltime isnotenough Enlargethepalletopenwindowforthedefectlocationstoreducethe T 某些元件位置被回流托盘遮挡造成该点峰值温度太低或回流时间不足 对缺陷位置放大托盘的开口从而减少温差 T 2020 4 17 25 Solderhole 锡洞 Blowholes pinholes voids吹孔 针孔 空洞 2020 4 17 26 Solderhole 锡洞 Countermeasure 对策1 Insufficientpreheat Reflowprofileoptimize 预热时间不足 优化回流曲线设置 2 Rampupistoofast Re setupthereflowprofiletomakeitoptimize 升温速率太快 重设回流曲线图使之最优化 3 Excessfluxinsolderpaste properlytoincreasepreheattimeandtemperature 锡膏助焊剂含量过多 适当增加预热时间和温度值 4 DampPCB BakethePCBbeforeloadingittoSMT PCB受潮 SMT组装前烘烤PCB板 5 Componentfeetoxidation BakeitbeforeSMTorrequirevacuumpackingonincomingmaterial 元件脚氧化 烘烤或者来料真空包装 6 Attachedfluxresidueoncomponentfoot Sortoutthedefectpart 元件脚有助焊剂残渣 挑选出缺陷来料 2020 4 17 27 DisturbedSolder 焊锡紊乱 Disturbedsolderjointcharacterizedbystresslinesfrommovementintheconnection 在冷却时受外力影响 呈现紊乱痕迹的焊锡 2020 4 17 28 DisturbedSolder 焊锡紊乱 Countermeasure1 Optimizereflowsolderingprofileespeciallyforcoolingzone 优化冷却区回流曲线2 ConveyorshakinginPCAcoolingdownphase Repairtheconveyorperactualstatus 冷却阶段传送带震动 根据实际情况调校传送带 2020 4 17 29 SolderProjections 锡尖 Solderprojectionviolatesassemblymaximumheightrequirementsorleadprotrusionrequirements 焊锡毛刺违反组装的最大高度要求或引脚凸出要求 Solderprojectionviolatesminimumelectricalclearance 焊锡毛刺违反最小电气间隙 2020 4 17 30 SolderProjections 锡尖 Countermeasure1 Lessfluxonboard Increasethefluxsprayrateonboardbeforegothroughwavesoldering wavesolder 助焊剂不足 增加助焊剂的喷射量2 Lowconveyorramp Raisetheconveyorrampperactualstatus wavesolder 传送带角度过小 根据实际情况校正传送带角度3 Excesspreheattemperatureandtime fluxdryoff Optimizewavesolderingprofile Wavesolder 预热过度 助焊剂过度挥发 优化波峰曲线 波峰焊 4 Causedbyrework Standardizeoperatorhandlingandenhancevisualinspection 返修中产生 规范员工操作加强目检 2020 4 17 31 NoSolder 无锡 Nosoldertothelandorterminationwheresolderisrequired 焊点无锡 2020 4 17 32 NoSolder 无锡 Countermeasure 对策1 Missingprinting 漏印Rootcause a Stencilaperturewasjammed 钢网堵孔b Highviscosityofsolderpaste 锡膏粘性过高Action a Cleanstencil 清洗钢网b Replacetherecycledpastewithfreshone 更换新锡膏c Printingmachineparameteradjustment 校正丝印机参数2 Poorsolderabilityofcomponentorpad 元件或焊盘可焊性太低Rootcause a OlddatecomponentorPCB 陈旧元件或PCB板b ContaminationoncomponentorPCB 元件或焊盘受污染Action Purgethematerialforfurtherdisposition 清除来料3 Insufficientfluxvolume increasefluxsprayrate wavesolder 助焊剂量不足 增加助焊剂喷射量 波峰焊接 4 Preheatexcess lowerpreheattemperatureproperly wavesolder 预热过度 适当降低预热温度 波峰焊 5 Chipwaveorsolderwaveheightislow properheight wavesolder 波峰高度过低 调整到适当高度 波峰焊 2020 4 17 33 InsufficientSolder 少锡 Insufficientsolder焊锡不足 2020 4 17 34 InsufficientSolder 少锡 Countermeasure 对策1 Stencilaperturecloggingcauseincompletesolderprinting Automaticormanualcleanthestencil 钢网孔堵塞导致锡膏不完全印刷 自动或者手工清洗钢网2 Noenoughsolderpastevolume PasteheightunderLCL VisualinspectionandCpkcontrol 锡膏量不足 锡膏高度在LCL以下 目检和Cpk控制3 Solderpasteprintmisalignment Finetuneprintingmachine锡膏印刷偏位 校正丝印机使之最优 4 PoorsolderabilityofcomponentorPCBpad 元件或PCB焊盘可焊性差a Optimizereflowprofile 优化回流曲线b Exchangethepoorsolderabilitycomponent 更换掉低可焊性元件5 Excessglueorgluemisalignment Finetunescreenprint wavesolder 点胶过多或点胶偏位 优化丝印参数6 Lessflux Increasethefluxsprayonboardbeforeitpasswavesoldering wavesolder 助焊剂不足 增加助焊剂的喷射量 2020 4 17 35 Solderfilletextendsontothetopofthecomponentbody 焊锡接触元件体 ExcessSolder 多锡 2020 4 17 36 ExcessSolder 多锡 Countermeasure 对策1 Excesssolderpaste 锡膏量过多a SolderpasteheightoutofUCL Adjustprintingmachinetocontrolthepasteheight 锡膏高度超出UCL 校正丝印机控制锡膏高度b Nonstandardofstencilapertureopening standardizethestencilapertureopeningfordifferenttypecomponents 钢网开孔不标准 为不同类型的元件设置相应钢网的开孔标准2 Wavesoldering 波峰焊接a Lowconveyerramp longwavesolderingtime Adjustconveyorrampangleto5 7degreeandsolderingtimeto3 5second 传送带角度过小 波峰焊接时间变长 校正传送带角度到5 7度 焊接时间3 5秒b Highpreheattemperaturetodryofftheflux Accordingtofluxspectocontrolthepreheattemperature normallythePCBsurfacepreheattemperatureshouldbeunder100oC 高预热温度造成助焊剂过度挥发 按照助焊剂的规格控制预热温度 通常 PCB表面温度一般低于100oC 2020 4 17 37 WrongOrientation Polarity反向 极性反 Correctpolarity 正确的极性 Wrongpolarity 极性反 Thismarkisa