元件吃錫效果與PCBLayout關(guān)系課件

元件吃錫效果與PCBLayout關(guān)系1PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO進板方向GOOD1.TWOSMDTOOCLOSE2.SMT本體易產(chǎn)生陰影效應8JES326S.0A3PCB進板方向2PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO光學點反黑範圍太小此光學點可以不用LAYOUT8JES326S.0A3PCB光學點太小3PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO陰影效應8JES326S.0A3PCB陰影效應進板方向LAYOUT請註明進板方向5PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOGOOD(BIGPAD)8JES326S.0A3PCBBIGPAD6PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO太密易造成短路沒拖錫點LAYOUT8JES326S.0A3PCBCONNECTERSHORT7PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO8JES326S.0A3PCB加白點有助減少short缺點,最好加一白線加白漆防焊(文字印刷)9PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO8JES326S.0A3PCBPhonejack和SMD太近且SMTcomponent太近易短路現(xiàn)象發(fā)生進板方向PAD&PADTOOCLOSE10PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO8JES326S.0A3PCB光學點離pad太近(BGA會打不準)光學點&PADTOOCLOSE11PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOS1024B.5A18EPCB增加拖錫點避免短路發(fā)生

進板方向LAYOUT請註明進板方向增加拖錫點防止短路沒有作用的拖錫點增加拖錫點避免短路發(fā)生

沒有作用的拖錫點13PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOS1024B.5A18EPCBSOLDERSIDEIC容易短路IC最好LAY在正板或以45°LAYOUT較不易造成PIN腳短路否則需用昂貴治具COVERICONSOLDERSIDELAYOUTDIRECTION14PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOS1024B.5A18EPCB不要利用螺絲孔接地PAD&SCREWHOLEGROUNDING15PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOS1024B.5A18EPCB以馬賽克LAYOUT方式較好(熱平衡)DUMMYPAD17PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO防焊防止PTH拉錫18PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOTOOCLOSE容易SHORTCOMPONENTTOOCLOSE19PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO容易SHORT吃錫後外觀不良???EASYSHORT21PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO陰影效應22PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO拖錫棒避免SOCKETSHORT拖錫棒進板方向LAYOUT請註明進板方向23PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO進板方向Layout沒考量進板方向,假pad放錯邊SOLDERDIRECTION25PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO此處淚滴(TEARDROP)設計較好,狗骨頭(DOGBONS)不好DOGBONS26PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO不好的layout吃錫易不足散熱快goodHEATTRANSFER29PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO測試點layoutTESTPOINT30PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO過Wavesolder時電解質(zhì)電容容易遭熱氣上沖而Fail電容易被熱氣沖壞31PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOBGALAYOUT:DOGBONSBETTERTHANTEARDROPDogboneVsTeardrop32PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO背板拖錫棒拖錫進板方向33PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO測試點LAYOUT方式TESTPOINT34PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOWAVESOLDERPROFILE35PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOAssembly36PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSMTProcessFlow37PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSMTProcessFlow38PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSMTProcessFlow39PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSMTProcessFlow40PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSMTProcessFlow41PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOWavesolderingProfile42PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOMachinesetupandprocesscharacteristicsBoard/wavecontactlengthBoarddwelltimeinsolderwave(s)Boardimmersiondepthinwaves(s)ConveyorspeedConveryortowaveorientationPreheattemperatureslopeMaxpreheattemperatureTemperaturespikeatthewave(s)Soldertemperatureinthewave(s)Timeaboveliquidus43PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOIRReflowSolderprofile44PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOVaporPhasereflowsolderProfile45PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOPreheatingToreducethermalshocktoPWBfromsolderwaveToactivethefluxbyheatingit.Todrythefluxwhichwouldotherwiseboilduringsoldering,causingsolderballs.Topreventtheboardwarpingduringsoldering.46PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOStencil47PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOKeypointofProcess(1)ConveyorspeedBoardspollutionDwelltimeSoldertemperatureSolderpotcontaminationTypeoffluxFluxcontaminationFluxfoamedunevenPreheatertemperatureSolderwaveunevenComponentscontaminationBoardsoxidedBoardsre-runDefectivefixtureFluxBlow-off(airknife)excessiveFluxnotmakingcontractBoardsnotseatedrightFluxfoamedlowFluxspecificgravity48PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOKeypointofProcess(2)IncorrectfluxbubblesizeImproperboardhandlingSolderwaveturbulentFluxnolongeractivePalletdesignDefectivemaskmaterialsInternalplanes(Multilayer)LargeplanesonsoldersidePallettoohotTypeofcoatingBoardwrappedFluxBlow-off(airknife)notonIncorrectweightplacementMisregistrationofmaskBasematerial(epoxyresin)49PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUODefectandCounterdefectForce50PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUODrawbridge51PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOConveyorangle52PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSolderjointfail

ResidualplatingchemicalsIncompletecleaningafterplatingSurfacecontaminationSurfaceoxidation53PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUOSOLDERBUMPING:VOIDING1.solventsinthefluxsystemunabletodiffusethroughthemoltensolderduringreflow2.alloyshrinkageoncooling3.jointshape-thepathofescapeforvaporscanbedifficultandleadtoentrappedgases4.improperornon-optimizedheatingprofile5.platingorsoldermaskrelatedissues(outgassing,inadequatecleaning,etc.)6.typeofsolderpasteandpowdersizeused54PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO印刷電路板方向不當 尺寸設計不良 未置於定位 有異物或受污染受重壓寬幅不當保護層處理不當印刷電路板或零件過期及儲存不當重量分佈不當氧化破損插件面設計不良載重過多變形焊錫面設計不良多層板內(nèi)電路設計不良55PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO印刷電路板印刷油墨不良 過量印刷油墨印刷油墨未稱位抗焊印刷不良 抗焊印刷不夠貼合層內(nèi)有濕氣不完全蝕刻 不良穿孔 空洞太大環(huán)氧樹脂基材外露環(huán)氧樹脂基材問題 56PHOTOBYQC/WONDERNOTEDBYMED/STEVENKUO零件零件方向不當零件受污染零件披覆材質(zhì)不良零件散熱不良零件腳長度57PHOTOBYQC/WONDERN