smt表面安裝技術(shù)缺陷市公開課一等獎(jiǎng)省賽課獲獎(jiǎng)?wù)n件

/10/101SMTdefectsandcountermeasureSMT缺點(diǎn)及防范辦法smt表面安裝技術(shù)缺陷第1頁/10/102IdentifySMTdefectsIdentifytheSMTdefectsaccordingtoIPC-A-610(Rev:D)依據(jù)IPC-A-610(Rev:D)確定缺點(diǎn)．

Thisstandardisacollectionofvisualqualityacceptabilityrequirementsforelectronicassemblies.IPC-A-610是關(guān)于電子組裝外觀質(zhì)量驗(yàn)收條件要求文件．smt表面安裝技術(shù)缺陷第2頁/10/103Majorcontributortodefects

缺點(diǎn)主要分布Source:MPM’sAuser’sguidetomorePreciseSMTprintingsmt表面安裝技術(shù)缺陷第3頁/10/104Knowthecommondefect

了解常見缺點(diǎn)類型Analysizethepossiblecause

分析可能原因Countermeasureforthedefects

基于以上原因采取對(duì)策

LearningObjectives

學(xué)習(xí)目smt表面安裝技術(shù)缺陷第4頁/10/105?

Chip

components

standing

on

a

terminal

end

(tombstoning).片式元件末端翹起（墓碑）Tombstoning/立碑smt表面安裝技術(shù)缺陷第5頁/10/106Countermeasure/對(duì)策M(jìn)echanism:Surfacetensionincomponentterminalisuneveninreflow.原理:在回流過程中零件兩末端表面張力不均衡.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):改進(jìn)PCB焊盤設(shè)計(jì).Tombstoning/立碑smt表面安裝技術(shù)缺陷第6頁/10/107Countermeasure/對(duì)策

3.Componentterminaloxidizationorcontamination:SolderabilitytestifnecessaryandRTVthedefectmaterial.

元件末端氧化或者受污染:依據(jù)情況做可焊性試驗(yàn)而且退還缺點(diǎn)物料.4.Printingmisalignment:adjustprintingmachineparameters.絲印偏位:校正絲印機(jī)參數(shù).5.Placementmisalignment:OptimizetheP&Pmachineparameters.

貼片偏位:優(yōu)化貼片機(jī)參數(shù).6.Stencilaperturedesignissue:studyandimprovetheaperturedesign.

鋼網(wǎng)開孔設(shè)計(jì)問題:研究而且改進(jìn)開孔設(shè)計(jì).

Tombstoning/立碑smt表面安裝技術(shù)缺陷第7頁/10/108?Asolderconnectionacrossconductorsthatwasjoined.焊錫在導(dǎo)體間非正常連接.?Solderhasbridgedtoadjacentnon-commonconductororcomponent.焊錫橋連到相鄰非導(dǎo)體或元件.Solderbridge/橋聯(lián)smt表面安裝技術(shù)缺陷第8頁/10/109Countermeasure/對(duì)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)或者使用低粘性錫膏.d)Solderpastecollapse:changetohigherviscositypaste./錫膏塌陷:使用高粘性錫膏.e)Nonstandardstencilapertureopening:Studyandimprovetheaperture./不標(biāo)準(zhǔn)鋼網(wǎng)開孔:研究并改進(jìn)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smt表面安裝技術(shù)缺陷第9頁/10/1010Countermeasure/對(duì)策2.Pick&Placement/貼片a)Componentplacingmisalignment:FinetunetheP&Pmachine.元件貼片偏位:優(yōu)化貼片機(jī)參數(shù).b)Highpressureforplacement:reducepressuretopropervalue.

貼片壓力過大:降低壓力到適當(dāng)參數(shù).3.Wavesoldering/波峰焊a)Lowconveyorramp:Raisetheconveyorrampperactualstatus.傳送帶角度過小:依據(jù)實(shí)際情況加大傳送帶角度b)Lessfluxonboard:Increasethefluxsprayvolumeonboardbeforegoingthroughwavesoldering.板上助焊劑較少:波峰焊接之前加大助焊劑噴射量Solderbridge/

橋聯(lián)smt表面安裝技術(shù)缺陷第10頁/10/1011Componentdamaged(Nicks,cracks,orstressfractures)/元件損壞Nicks,cracks,orstressfractures.缺口，裂紋，壓痕smt表面安裝技術(shù)缺陷第11頁/10/1012Countermeasure/對(duì)策1.Rawmaterialdamaged:purgethebatchmaterial./來料損壞:去除這批來料.2.DamagedduringSMTprocess(Fixtureormachinetouchit):Investigateandtakecorrectiveactionsfornonstandardoperation.

在SMT流程中損壞(夾具和設(shè)備接觸):調(diào)查分析而且對(duì)不規(guī)范操作作出矯正行動(dòng).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:PreheatstageSoakstageReflowstagePeaktemp.Cooldown<4oC/sComponentdamaged(Nicks,cracks,orstressfractures)/元件損壞smt表面安裝技術(shù)缺陷第12頁/10/1013Misalignment偏位smt表面安裝技術(shù)缺陷第13頁/10/1014Countermeasure/對(duì)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./校正吸料和貼片參數(shù).

2.Componentterminationoxidization:Solderabilitytestifnecessary.Purgethefailedmaterial/元件末端氧化:可焊性試驗(yàn),去除不合格來料.

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smt表面安裝技術(shù)缺陷第14頁/10/1015Componentleadlifted元件引腳翹高One

leadorseriesofleadsoncomponentisoutofalign-ment

and

fails

to

make

contact

with

the

land.元件一個(gè)或多個(gè)引腳變形不能與焊盤正常接觸．smt表面安裝技術(shù)缺陷第15頁/10/1016Componentleadlifted元件引腳翹高Countermeasure/對(duì)策1.Componentleadbentbeforeplacement:Sortthedefectivepartandreturnittovendor.貼片前元件引腳變形:挑選出缺點(diǎn)元件,退回供給商．2.Manualplacementtheloosepart:Inspectthepartbeforepassittoreflow.手放散料:回流前目檢．smt表面安裝技術(shù)缺陷第16頁/10/1017Solderball錫珠Solderballsarespheresofsolderthatremainafterthesolderingprocess.Solderballsviolateminimumelectricalclearance.焊錫球是焊接后形成呈球狀焊錫.

Solderfinesaretypicallysmallballsoftheoriginalsolderpastemetalscreensizethathavesplatteredaroundtheconnectionduringthereflowprocess.焊錫殘?jiān)窃诨亓髦行纬尚∏驙罨虿灰?guī)則狀焊錫球.smt表面安裝技術(shù)缺陷第17頁/10/1018Solderball錫珠

Countermeasure/對(duì)策1.StencilAperturedonotfocustopad:improvestencilapertureopening.

鋼網(wǎng)開孔沒有對(duì)準(zhǔn)焊盤中心:改進(jìn)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)置太高致使多出焊錫到頂面:校正波峰焊設(shè)置到適當(dāng)高度

(波峰焊接).smt表面安裝技術(shù)缺陷第18頁/10/1019Non-Wetting,Dewetting/虛焊，半潤濕

?

Solder

has

not

wetted

to

the

land

or

termination

where

solderisrequired.

虛焊:需要焊接引腳焊盤不潤濕．

?Solder

coverage

does

no

meet

requirements

for

the

termination

type.

?

Dewettingasaconditionresultswhenmoltensoldercoatsasurfaceandthenrecedestoleaveirregularly-shapedmoundsofsolderthatareseparatedbyareasthatarecoveredwithathinfilmofsolderandwiththebasismetalorsurfacefinishnotexposed.

半潤濕:熔化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.smt表面安裝技術(shù)缺陷第19頁/10/1020Non-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.

/去除來料2.Thepasteoutofitslifetime:/錫膏超出使用期Scrapthelotpasteandreplaceitwithfreshone報(bào)廢有問題錫膏更換新錫膏smt表面安裝技術(shù)缺陷第20頁/10/1021Coldsolder/冷焊

?Incompletereflowofsolderpaste.焊錫回流不完全smt表面安裝技術(shù)缺陷第21頁/10/1022Coldsolder/冷焊

Countermeasure/對(duì)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:/經(jīng)典回流曲線PreheatstageSoakstageReflowstagePeaktemp.Cooldown<4oC/ssmt表面安裝技術(shù)缺陷第22頁/10/1023Time時(shí)間Temp.溫度230°C250°Ctc1–smallSMDtc1–mediumSMDtc3–largeSMD20°C20°CTooHot!TooCold!Peak:230–250°CColdsolder/冷焊smt表面安裝技術(shù)缺陷第23頁/10/1024Coldsolder/冷焊

Countermeasure/對(duì)策2.Thecomponentinsomelocationcoveredwithreflowpallet(Peaktemperatureistooloworreflowtime(dwelltime)

isnotenough):EnlargethepalletopenwindowforthedefectlocationstoreducetheΔT.一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(duì)缺點(diǎn)位置放大托盤開口從而降低溫差（ΔT）.

smt表面安裝技術(shù)缺陷第24頁/10/1025Solderhole/錫洞

?Blowholes,pinholes,voids吹孔,針孔,空洞smt表面安裝技術(shù)缺陷第25頁/10/1026Solderhole/錫洞

Countermeasure/對(duì)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:BakethePCBbeforeloading

ittoSMT.

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)?挑選出缺點(diǎn)來料.

smt表面安裝技術(shù)缺陷第26頁/10/1027DisturbedSolder/焊錫紊亂

?Disturbed

solderjointcharacterizedbystresslinesfrommovementintheconnection.在冷卻時(shí)受外力影響,展現(xiàn)紊亂痕跡焊錫smt表面安裝技術(shù)缺陷第27頁/10/1028DisturbedSolder/焊錫紊亂Countermeasure1.Optimizereflowsoldering

profileespeciallyforcoolingzone.優(yōu)化冷卻區(qū)回流曲線2.ConveyorshakinginPCAcoolingdownphase:Repairthe

conveyorperactualstatus.冷卻階段傳送帶震動(dòng):依據(jù)實(shí)際情況調(diào)校傳送帶．smt表面安裝技術(shù)缺陷第28頁/10/1029SolderProjections/錫尖Solderprojectionviolatesassemblymaximumheightrequirementsorleadprotrusionrequirements.焊錫毛刺違反組裝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.smt表面安裝技術(shù)缺陷第29頁/10/1030SolderProjections/錫尖Countermeasure1.Lessfluxonboard:Increasethefluxsprayrateonboardbeforegothroughwavesoldering(wavesolder).助焊劑不足:增加助焊劑噴射量

2.Lowconveyorramp:Raisetheconveyorrampperactualstatus(wavesolder).傳送帶角度過小:依據(jù)實(shí)際情況校正傳送帶角度3.Excesspreheattemperatureandtime(fluxdryoff):Optimizewavesolderingprofile.(Wavesolder)預(yù)熱過分（助焊劑過分揮發(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.smt表面安裝技術(shù)缺陷第30頁/10/1031NoSolder/無錫

Nosolder

to

the

land

or

termination

where

solderisrequired.焊點(diǎn)無錫smt表面安裝技術(shù)缺陷第31頁/10/1032NoSolder/無錫

Countermeasure/對(duì)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.

/去除來料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)熱過分: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)smt表面安裝技術(shù)缺陷第32頁/10/1033InsufficientSolder/少錫Insufficientsolder焊錫不足smt表面安裝技術(shù)缺陷第33頁/10/1034InsufficientSolder/少錫

Countermeasure/對(duì)策1.Stencilaperturecloggingcauseincompletesolderprinting):Automaticormanualcleanthestencil.鋼網(wǎng)孔堵塞造成錫膏不完全印刷:自動(dòng)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:增加助焊劑噴射量

smt表面安裝技術(shù)缺陷第34頁/10/1035?Solderfilletextendsontothetopofthecomponentbody.焊錫接觸元件體．ExcessSolder/多錫smt表面安裝技術(shù)缺陷第35頁/10/1036ExcessSolder/多錫

Countermeasure/對(duì)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):為不一樣類型元件設(shè)置對(duì)應(yīng)鋼網(wǎng)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分揮發(fā):按照助焊劑規(guī)格控制預(yù)熱溫度,通常,PCB表面溫度普通低于100oCsmt表面安裝技術(shù)缺陷第36頁/10/1037WrongOrientation/Polarity反向,極性反

Correctpolarity/正