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 根據(jù)IPC A 610 Rev D 確定缺陷 Thisstandardisacollectionofvisualqualityacceptabilityrequirementsforelectronicassemblies IPC A 610是關(guān)于電子組裝外觀質(zhì)量驗(yàn)收條件要求的文件 2020 4 17 3 Majorcontributortodefects缺陷的主要分布 Source MPM sAuser sguidetomorePreciseSMTprinting 2020 4 17 4 Knowthecommondefect了解常見缺陷類型Analysizethepossiblecause分析可能的原因Countermeasureforthedefects基于以上原因采取的對策 LearningObjectives學(xué)習(xí)目的 2020 4 17 5 Chipcomponentsstandingonaterminalend tombstoning 片式元件末端翹起 墓碑 Tombstoning 立碑 2020 4 17 6 Countermeasure 對策M(jìn)echanism Surfacetensionincomponentterminalisuneveninreflow 原理 在回流過程中零件兩末端的表面張力不均衡 1 Componentterminalheatdistributedunevenly零件兩末端受熱分布不均衡 Insufficientsoaktime Reflowprofileoptimization 保溫區(qū)時(shí)間太短 優(yōu)化回流曲線參數(shù) 2 PCBPaddesignissue thepadsdistanceistoobig improvePCBpaddesign PCB焊盤設(shè)計(jì)問題 焊盤間距太大 改善PCB焊盤設(shè)計(jì) Tombstoning 立碑 2020 4 17 7 Countermeasure 對策3 Componentterminaloxidizationorcontamination SolderabilitytestifnecessaryandRTVthedefectmaterial 元件末端氧化或者受污染 根據(jù)情況做可焊性實(shí)驗(yàn)并且退還缺陷物料 4 Printingmisalignment adjustprintingmachineparameters 絲印偏位 校正絲印機(jī)的參數(shù) 5 Placementmisalignment OptimizetheP Pmachineparameters 貼片偏位 優(yōu)化貼片機(jī)的參數(shù) 6 Stencilaperturedesignissue studyandimprovetheaperturedesign 鋼網(wǎng)開孔的設(shè)計(jì)問題 研究并且改善開孔設(shè)計(jì) Tombstoning 立碑 2020 4 17 8 Asolderconnectionacrossconductorsthatwasjoined 焊錫在導(dǎo)體間非正常連接 Solderhasbridgedtoadjacentnon commonconductororcomponent 焊錫橋連到相鄰的非導(dǎo)體或元件 Solderbridge 橋聯(lián) 2020 4 17 9 Countermeasure 對策1 Screenprintingissue 絲印問題 a PasteheightoutofUCL Adjusttheprintertocontrolthepasteheight 錫膏高度超出控制上線 校正絲印機(jī) 控制錫膏高度 b Pasteprintingmisalignmentorbridging Finetuneprintingmachine 錫膏印刷偏位或者橋聯(lián) 優(yōu)化絲印機(jī) c Icicleprinting Finetuneprintingmachineorchangetolowerviscositypaste 絲印拉尖 優(yōu)化絲印機(jī)或者使用低粘性的錫膏 d Solderpastecollapse changetohigherviscositypaste 錫膏塌陷 使用高粘性的錫膏 e Nonstandardstencilapertureopening Studyandimprovetheaperture 不標(biāo)準(zhǔn)的鋼網(wǎng)開孔 研究并改善開孔 Solderbridge 橋聯(lián) Icicleprinting絲印拉尖 Pastecollapse錫膏塌陷 Bridging橋聯(lián) Misalignment印刷偏位 2020 4 17 10 Countermeasure 對策2 Pick Placement 貼片a Componentplacingmisalignment FinetunetheP Pmachine 元件貼片偏位 優(yōu)化貼片機(jī)的參數(shù) b Highpressureforplacement reducepressuretopropervalue 貼片壓力過大 減少壓力到適當(dāng)?shù)膮?shù) 3 Wavesoldering 波峰焊a Lowconveyorramp Raisetheconveyorrampperactualstatus 傳送帶角度過小 根據(jù)實(shí)際情況加大傳送帶角度b Lessfluxonboard Increasethefluxsprayvolumeonboardbeforegoingthroughwavesoldering 板上的助焊劑較少 波峰焊接之前加大助焊劑的噴射量 Solderbridge 橋聯(lián) 2020 4 17 11 Componentdamaged Nicks cracks orstressfractures 元件損壞 Nicks cracks orstressfractures 缺口 裂紋 壓痕 2020 4 17 12 Countermeasure 對策1 Rawmaterialdamaged purgethebatchmaterial 來料損壞 清除這批來料 2 DamagedduringSMTprocess Fixtureormachinetouchit Investigateandtakecorrectiveactionsfornonstandardoperation 在SMT流程中損壞 夾具和設(shè)備接觸 調(diào)查分析并且對不規(guī)范的操作作出矯正行動 3 Fastcoolingrateonreflowprocess Controlthecoolingratetobelow4degreepersecond 在回流過程中冷卻速率過快 控制冷卻速度使斜率保持在每秒4度以下 Typicalreflowprofile 回流曲線典例 Componentdamaged Nicks cracks orstressfractures 元件損壞 2020 4 17 13 Misalignment偏位 2020 4 17 14 Countermeasure 對策1 P Pmachinefunctionunstable FinetunetheP Pmachine 貼片機(jī)性能不穩(wěn)定 優(yōu)化貼片機(jī)性能參數(shù) a FinetuneX Ydata 調(diào)整X Y坐標(biāo)b Optimizepickandplacementparameters 校正吸料和貼片的參數(shù) 2 Componentterminationoxidization Solderabilitytestifnecessary Purgethefailedmaterial 元件末端氧化 可焊性實(shí)驗(yàn) 清除不合格的來料 3 Operatortouchthecomponentpriortoreflow Standardizetheoperatorhandling documentcontrol 在回流爐前目檢操作員碰到貼片元件 標(biāo)準(zhǔn)化操作員操作 文件控制 4 Airflowrateinthereflowovenissohighthatthecomponentsaremoved 回流爐內(nèi)空氣流量太高以致吹偏了元件 Misalignment偏位 2020 4 17 15 Componentleadlifted元件引腳翹高 Oneleadorseriesofleadsoncomponentisoutofalign mentandfailstomakecontactwiththeland 元件一個或多個引腳變形不能與焊盤正常接觸 2020 4 17 16 Componentleadlifted元件引腳翹高 Countermeasure 對策1 Componentleadbentbeforeplacement Sortthedefectivepartandreturnittovendor 貼片前元件引腳變形 挑選出缺陷元件 退回供應(yīng)商 2 Manualplacementtheloosepart Inspectthepartbeforepassittoreflow 手放散料 回流前目檢 2020 4 17 17 Solderball錫珠 Solderballsarespheresofsolderthatremainafterthesolderingprocess Solderballsviolateminimumelectricalclearance 焊錫球是焊接后形成的呈球狀焊錫 Solderfinesaretypicallysmallballsoftheoriginalsolderpastemetalscreensizethathavesplatteredaroundtheconnectionduringthereflowprocess 焊錫殘?jiān)窃诨亓髦行纬傻男〉那驙罨虿灰?guī)則狀焊錫球 2020 4 17 18 Solderball錫珠 Countermeasure 對策1 StencilAperturedonotfocustopad improvestencilapertureopening 鋼網(wǎng)開孔沒有對準(zhǔn)焊盤中心 改善鋼網(wǎng)開孔 2 Printingmisalignment Finetuneprintmachine 絲印偏位 調(diào)整絲印機(jī)狀態(tài) 3 Excesspaste Cpkcontrol 多錫 Cpk控制 4 DampPCB BakethePCBbeforeloadingittoSMT PCB焊盤受潮 SMT組裝流程之前烘烤PCB 6 Stencilpolluted cleanthestencil 鋼網(wǎng)臟污 清洗鋼網(wǎng) 7 Profilerampupistoofast Optimizereflowprofile 回流曲線升溫速度過快 優(yōu)化回流曲線 8 Pasteoxidized exchangewithfreshsolderpaste 錫膏氧化 更換新錫膏 9 Chipwaveorsolderwaveheightistoohighcausedexcesssoldertotopside adjustthewavesolderingheighttoproperlevel wavesolder 波峰高度設(shè)置的太高致使多余的焊錫到頂面 校正波峰焊設(shè)置到適當(dāng)?shù)母叨?波峰焊接 2020 4 17 19 Non Wetting Dewetting 虛焊 半潤濕 Solderhasnotwettedtothelandorterminationwheresolderisrequired 虛焊 需要焊接的引腳焊盤不潤濕 Soldercoveragedoesnomeetrequirementsfortheterminationtype Dewettingasaconditionresultswhenmoltensoldercoatsasurfaceandthenrecedestoleaveirregularly shapedmoundsofsolderthatareseparatedbyareasthatarecoveredwithathinfilmofsolderandwiththebasismetalorsurfacefinishnotexposed 半潤濕 熔化的焊錫浸潤表面后收縮 留下一焊錫薄層覆蓋部分區(qū)域 焊錫形狀不規(guī)則 2020 4 17 20 Non Wetting Dewetting 虛焊 半潤濕 1 Poorsolderabilityofcomponentorpad 元件或焊盤可焊性太低Rootcause a OlddatecomponentorPCB 陳舊元件或PCB板b ContaminationoroxidationoncomponentorPCB 元件或焊盤污染或氧化Action Purgethematerialforfurtherdisposition 清除來料2 Thepasteoutofitslifetime 錫膏超出有效期Scrapthelotpasteandreplaceitwithfreshone報(bào)廢有問題的錫膏更換新錫膏 2020 4 17 21 Coldsolder 冷焊 Incompletereflowofsolderpaste 焊錫回流不完全 2020 4 17 22 Coldsolder 冷焊 Countermeasure 對策1 Peaktemperatureistooloworreflowtime dwelltime isnotenough Re setuptheprofiletofulfillthepastespecorcustomerprovidedspec requirement 回流峰值溫度太低或者回流時(shí)間不夠 重設(shè)溫度曲線圖 Typicalreflowprofile 典型的回流曲線 2020 4 17 23 Time時(shí)間 Temp 溫度 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 對策2 Thecomponentinsomelocationcoveredwithreflowpallet Peaktemperatureistooloworreflowtime dwelltime isnotenough Enlargethepalletopenwindowforthedefectlocationstoreducethe T 某些元件位置被回流托盤遮擋造成該點(diǎn)峰值溫度太低或回流時(shí)間不足 對缺陷位置放大托盤的開口從而減少溫差 T 2020 4 17 25 Solderhole 錫洞 Blowholes pinholes voids吹孔 針孔 空洞 2020 4 17 26 Solderhole 錫洞 Countermeasure 對策1 Insufficientpreheat Reflowprofileoptimize 預(yù)熱時(shí)間不足 優(yōu)化回流曲線設(shè)置 2 Rampupistoofast Re setupthereflowprofiletomakeitoptimize 升溫速率太快 重設(shè)回流曲線圖使之最優(yōu)化 3 Excessfluxinsolderpaste properlytoincreasepreheattimeandtemperature 錫膏助焊劑含量過多 適當(dāng)增加預(yù)熱時(shí)間和溫度值 4 DampPCB BakethePCBbeforeloadingittoSMT PCB受潮 SMT組裝前烘烤PCB板 5 Componentfeetoxidation BakeitbeforeSMTorrequirevacuumpackingonincomingmaterial 元件腳氧化 烘烤或者來料真空包裝 6 Attachedfluxresidueoncomponentfoot Sortoutthedefectpart 元件腳有助焊劑殘?jiān)?挑選出缺陷來料 2020 4 17 27 DisturbedSolder 焊錫紊亂 Disturbedsolderjointcharacterizedbystresslinesfrommovementintheconnection 在冷卻時(shí)受外力影響 呈現(xiàn)紊亂痕跡的焊錫 2020 4 17 28 DisturbedSolder 焊錫紊亂 Countermeasure1 Optimizereflowsolderingprofileespeciallyforcoolingzone 優(yōu)化冷卻區(qū)回流曲線2 ConveyorshakinginPCAcoolingdownphase Repairtheconveyorperactualstatus 冷卻階段傳送帶震動 根據(jù)實(shí)際情況調(diào)校傳送帶 2020 4 17 29 SolderProjections 錫尖 Solderprojectionviolatesassemblymaximumheightrequirementsorleadprotrusionrequirements 焊錫毛刺違反組裝的最大高度要求或引腳凸出要求 Solderprojectionviolatesminimumelectricalclearance 焊錫毛刺違反最小電氣間隙 2020 4 17 30 SolderProjections 錫尖 Countermeasure1 Lessfluxonboard Increasethefluxsprayrateonboardbeforegothroughwavesoldering wavesolder 助焊劑不足 增加助焊劑的噴射量2 Lowconveyorramp Raisetheconveyorrampperactualstatus wavesolder 傳送帶角度過小 根據(jù)實(shí)際情況校正傳送帶角度3 Excesspreheattemperatureandtime fluxdryoff Optimizewavesolderingprofile Wavesolder 預(yù)熱過度 助焊劑過度揮發(fā) 優(yōu)化波峰曲線 波峰焊 4 Causedbyrework Standardizeoperatorhandlingandenhancevisualinspection 返修中產(chǎn)生 規(guī)范員工操作加強(qiáng)目檢 2020 4 17 31 NoSolder 無錫 Nosoldertothelandorterminationwheresolderisrequired 焊點(diǎn)無錫 2020 4 17 32 NoSolder 無錫 Countermeasure 對策1 Missingprinting 漏印Rootcause a Stencilaperturewasjammed 鋼網(wǎng)堵孔b Highviscosityofsolderpaste 錫膏粘性過高Action a Cleanstencil 清洗鋼網(wǎng)b Replacetherecycledpastewithfreshone 更換新錫膏c Printingmachineparameteradjustment 校正絲印機(jī)參數(shù)2 Poorsolderabilityofcomponentorpad 元件或焊盤可焊性太低Rootcause a OlddatecomponentorPCB 陳舊元件或PCB板b ContaminationoncomponentorPCB 元件或焊盤受污染Action Purgethematerialforfurtherdisposition 清除來料3 Insufficientfluxvolume increasefluxsprayrate wavesolder 助焊劑量不足 增加助焊劑噴射量 波峰焊接 4 Preheatexcess lowerpreheattemperatureproperly wavesolder 預(yù)熱過度 適當(dāng)降低預(yù)熱溫度 波峰焊 5 Chipwaveorsolderwaveheightislow properheight wavesolder 波峰高度過低 調(diào)整到適當(dāng)高度 波峰焊 2020 4 17 33 InsufficientSolder 少錫 Insufficientsolder焊錫不足 2020 4 17 34 InsufficientSolder 少錫 Countermeasure 對策1 Stencilaperturecloggingcauseincompletesolderprinting Automaticormanualcleanthestencil 鋼網(wǎng)孔堵塞導(dǎo)致錫膏不完全印刷 自動或者手工清洗鋼網(wǎng)2 Noenoughsolderpastevolume PasteheightunderLCL VisualinspectionandCpkcontrol 錫膏量不足 錫膏高度在LCL以下 目檢和Cpk控制3 Solderpasteprintmisalignment Finetuneprintingmachine錫膏印刷偏位 校正絲印機(jī)使之最優(yōu) 4 PoorsolderabilityofcomponentorPCBpad 元件或PCB焊盤可焊性差a Optimizereflowprofile 優(yōu)化回流曲線b Exchangethepoorsolderabilitycomponent 更換掉低可焊性元件5 Excessglueorgluemisalignment Finetunescreenprint wavesolder 點(diǎn)膠過多或點(diǎn)膠偏位 優(yōu)化絲印參數(shù)6 Lessflux Increasethefluxsprayonboardbeforeitpasswavesoldering wavesolder 助焊劑不足 增加助焊劑的噴射量 2020 4 17 35 Solderfilletextendsontothetopofthecomponentbody 焊錫接觸元件體 ExcessSolder 多錫 2020 4 17 36 ExcessSolder 多錫 Countermeasure 對策1 Excesssolderpaste 錫膏量過多a SolderpasteheightoutofUCL Adjustprintingmachinetocontrolthepasteheight 錫膏高度超出UCL 校正絲印機(jī)控制錫膏高度b Nonstandardofstencilapertureopening standardizethestencilapertureopeningfordifferenttypecomponents 鋼網(wǎng)開孔不標(biāo)準(zhǔn) 為不同類型的元件設(shè)置相應(yīng)鋼網(wǎng)的開孔標(biāo)準(zhǔn)2 Wavesoldering 波峰焊接a Lowconveyerramp longwavesolderingtime Adjustconveyorrampangleto5 7degreeandsolderingtimeto3 5second 傳送帶角度過小 波峰焊接時(shí)間變長 校正傳送帶角度到5 7度 焊接時(shí)間3 5秒b Highpreheattemperaturetodryofftheflux Accordingtofluxspectocontrolthepreheattemperature normallythePCBsurfacepreheattemperatureshouldbeunder100oC 高預(yù)熱溫度造成助焊劑過度揮發(fā) 按照助焊劑的規(guī)格控制預(yù)熱溫度 通常 PCB表面溫度一般低于100oC 2020 4 17 37 WrongOrientation Polarity反向 極性反 Correctpolarity 正確的極性 Wrongpolarity 極性反 Thismarkisa