SMT-PROCESS-INTRODUCE英文原版原文

SMTPROCESSINTRODUCE

S.M.T.

SurfaceMountTechnologyDEFINITION:Atechnologyformountingelectroniccomponents(=SMDs)onthesurfaceofsuitablesubstrateS.M.D.

SurfaceMountDeviceDEFINITION:(orsurfacemountcomponent,SMC),Itisaleadorleadlesselectroniccomponentthatiscapableofbeingattachedtoaprintedboardbysurfacemounting.WHATISSMT

SMTFLOW

ReceiveMaterialsPrepareMaterialsPrintingsolderpastePick&PlaceReflowReflowPick&PlacePrintingsolderpasteReverseBoardAOIAutoOpticalInspectionAOIAutoOpticalInspectionVisualInspectionNextProcedureSMTqualityissuesattributionSMTKEYEQUIPMENTStencilPrinterMPM;DEK;FUJI;MounterStructure:Turret---FUJICP8/CP6P&PModular---IP3;QP2/3Pick&Place---GSMP&PRotary---NXTSiemensHSFunction:Highspeed/Chipmounter:FUJICP;NXT*,Siemens..Functional/ICmounter:FUJIIP,QP,XP,UNIVERSALGSM2/GSM1ReflowHELLER;Soltec;BTU;SOLDERPRINTINGPURPOSEStencilprintingisdepositingthepropervolumeofsolderpasteinthepropershapesandareastoensurethat,afterreflow,solderjointsmeetbothmechanicalandelectricaldesignrequirements.Whyneedfocusonsolderprinting?PrintingisthefirststepinSMTassemblyandstatisticallyhasthehighestimpactonyieldandquality.Morethan60%ofSMTqualityissuescanbeattributedtotheprintingprocess.Themanydefectsofprintingcanbedetectedonlyafterreflow.OPERATIONIMPORTANTS

ProcessintroduceSolderpasteStencil/Squeegee/supportPinPrintingparameterMeasurement/InspectionFailuremodelProcessIntroduceXFYF=X+YF:theforcebysqueegeeX:Forcetopasteroll&forwardY:Makepastedowna.Solderpasteisrollingb.Producethepressuretomakepastedownc.Yforcemakepastedowninholed.PastesnapoffBestPrintConsistentsolderpasteheight;AccuratelocationCleanPCBSolderPaste

PASTE=POWDER+FLUXSolderPowderSizedistributionandvarianceShapeFluxActivatorSolventSurfactantCharacteristic

Volume:power50%Flux50%。Weight:Power90%Flux10%。ViscosityCommondensity:500-900Pa.sGenerally,80to90%forprintingand80to85%fordispensing.Highsolidscontentensuresthatpastedoesnotslumpasmuchandresultsinatallersolderfilletafterreflow.SolderpowerA:Unit

1、mesh:

thequantityofparticlethatsortwith1squareinchmesh

-----usefortheirregularparticlesize

2、μm:

(10-3mm),useopticalinspectortomeasuretheexactdiameterofsolderball

-----usefortheregularparticlesize(round)B:ComparisonMeshParticleSizePasteSizemmmilType200<753.0I270<552.2325<451.8III400<381.5IV500<251.0VIIRecommendationsforFinePitchLeadPitch

Meshtype

ParticleSize>25mil(0.635mm)Type3 -325/+40020mil(0.5mm) Type3-325/+50016mil(0.4mm) Type4,3 -400/+50012mil(0.3mm) Type4 -400/+625ParticleSizeFluxWhatisFluxAchemicalmixturethatremovemetaloxidesandprotectsmetallicsurfacesduringthesolderingprocessTheFunctionofFluxRemovesmetaloxidesanddissolvesorbreaksupforeignmaterialslikepreservatives,grease,andotherdirtLowersthesurfacetensionofmoltensolder,whichpromotesflowingProtectsthesolderingsurfacesduringheatingfromre-oxidationandremovesanymetaloxidesformedduringheatingFluxCompositionActivator:

●organicacids---有机酸●aminebases---胺类●rosin---松香Solvent ●waterbased----highheatcapacity ●organicbasedIPA----TotheIPA,itisahazardoussubstance-SurfactantFluxClassificationsR Rosin，non-activated---仅用于金属氧化物极易去除时RMA Rosin,MildlyActivated---室温时无腐蚀，不传导RA Rosin,Activated---用于金属氧化物难去除，残留有腐蚀，会传导OA OrganicActivated---水溶性助焊剂，含有机酸SA Synthetic,Activated---人工合成的助焊剂

No-CleanFluxesSolidscontent3%orlessResidueClearandalmostinvisibleChemicallyinertElectricallyinsulatingSolventWaterforVOC-freeno-cleanfluxIPAforVOC-containingfluxSolderabilityIssuesWeaksolderabilitySolderballingSolderpastemanagementA,Storage

Condition:0~10℃

B,Warm-upUsually4hours,baseonthesolderspecificationC,Mix

1.Mixthesolderpowderandflux,2.Pleasedon’tmixthesolderpastewiththedifferenttype,manufacturerStencilFinishLaser+ElectropolishStencilTightertolerances/moreaccurate.Moreexpensiveandrougherwalls.TrapezoidalaperturesallowforbetterreleaseChemicaletch

Acidetchaperturesfromimage.Lessexpensethanothermethods.PoorreleasecharacteristicsespeciallyatsmallerpitchesElectroformStencilUnlimitedthicknessvariability.Betterwearcharacteristics.Smooth,taperedaperturewalls.Bestreleasecharacteristics>95%.SpecialGasketingfeatureresultsinlessneededwiping,lessbleedthrough.ChemicalEtchLaserCutElectroformedStencilBoardPadApertureProfilesTHICKNESS1.0.15mmformostapplications2.0.20mmonlyforcoursepitch(SOICsandabove)3.0.10mmforultra-finepitch(below0.4mmpitch).4.0.25-0.30mmfor“bottomsidechipattach”gluePrincipia*Stencilthicknessisatleast4timesofsolderbiggestparticlediameter*FinestpitchonthePCBdeterminesstencilthicknessBeforeTheApertureDesignRemember:-theoptimumdimensionsdependonpastetype,printspeed,linebeatrate,squeegeetype........Iftheresultsarepoor,ignoretherules,changethedimensionsandinvestinnewstencil.ApertureAsfirstapproximationofaperturedimensions,totalvolumeof"surfacepaste",(=[stencilthickness]x[printarea]),addedtovolumeof"pasteinhole",(=[πD2/4]x[T])mustbegreaterthantwice([volumeofhole]-[volumeofwireinhole]),(=2[πT/4]x[D2-d2]whereD=holediameter,d=pindiameterandT=boardthickness).Thiswillprovideenoughpastetofillspacebetweenwireandholewithsoldermetal.Increaseprintareaby25%toprovidesolderforfillets.SqueegeeAngle60ºmostcommonlyused.45ºusefulwhenanunusuallythoroughpastetransferisnecessary,e.g.for“intrusivereflow/pininpaste”applicationsMaterialAdvantageDisadvantageRubberFlexible,Commonlyuseforstep-uporstep-downstencil,unevenstencilsurfaceEasytosunkinopening(Especiallybigopening)leadtopastescoopingoutEasytowearMetalEvenstencilsurfaceWearableUseforsmallpitch,highdensitySMTassemblyWidelyuseforSMTStencileasytodamageSupportBlock/PinPropersupportandholddownofboardisaMUSTforaccurateprinting.Thispreventstheboardfrommovingandbowingwhileprinting.Canprovide100%supportCancontainmilledoutareasforundersidecomponentsCanbefittedwithvacuumcups...ProgramparameterStencilWiping

Method/frequency:Method:Vacuum/Dry/WetFrequency:16mil,3-5prints;20mil,5-15prints;25mil,15-30prints;50mil,50-100prints.Printingspeed10—50mm/sSqueegeepressure0.45~0.7kg/inchPrintinggap0separatespeed0.5-2mm/secMeasurement/Inspection

SPI

VisionmasterAP212,LSM300(Off-line),SE300(On-line)Maymeasurepasteheight&Volume&AreaX-RChartFailuremodelInsufficientsolder

Stencilthickness;stencilopening;Squeegeeblade;Printingspeed;SqueegeepressureExcesssolder

Stencildamage;Boardsupport;TensionofstencilBridge(Smear)MisalignmentSolderball

WiperFrequencyandsetup;ToomuchSolvent–stencilstillwetafterwipeoccursPasteSlumpPICK/PLACEPURPOSEPlacetherightcomponentinthecorrectlocationOPERATIONIMPORTANTSMachineoverviewProgramRightpolarityFailuremodelMachineOverviewMachineOverview-Thefunctionofeach16stations

Program–FUJIFlexaDirector

(1)

TopData：X,Ycoordinate,Theta,slot….。(2)

General：PCBinformation,editthePCBlength,width,thickness….。(3)

MarkData：Markshape,dimension(4)

ShapeData：Partspecification(5)

PackageData:Feedertype(6）PartData:PartlibraryProgram–FUJIFlexaDirector

TopDataProgram–FUJIFlexaDirector

General：PCBinformation,editthePCBlength,width,thickness….。Program–FUJIFlexaDirector

MarkDataF

meansFiducialMarkSMeansBlockSkipMarkProgram–FUJIFlexaDirector

ShapeData按鼠标右键点击new在空白处按鼠标右键点击NewShapeNamePartShapeNozzleselectionPickupplacementsettingProgram–FUJIFlexaDirector

PackageData:FeedertypePackagingType：Paper/EmbossTapeWidth：8mm;12mm;16mm;24mmFeedPitch：FeedingdistanceWD0804–4mmProgram–FUJIFlexaDirector

PartData:PartlibraryConsolidatethepartshapeandpackage,definethepartcharacteristicRightpolarity

ShapedataPartdataX-YdataThreedirectionsFailureModelBillboarding(SideMounting)PossibleRootCauseMethod/ParametertoadjustPlacementissueCheckplacement,nozzlecondition,nozzlesizetopartFeederproblemReconfirmfeederorchangefeederIncorrectcomponentdataCheckdimensiontolerancesettingandensurethatitisspecifiedtolerancecriteria.

Checkmountingparameterspeciallymountheight.IncorrectcomponentpocketsizeChangetootherAVLorreelComponentissueContaminated/oxidizedcomponentterminalsMissingComponentPossibleRootCauseMethod/ParametertoadjustPlacementsetupissueVerify/adjustboardsupportpinsPlacementIssueCheckplacement,nozzlecondition,nozzlesizetopart,verifycorrectprogram/revisionisloadedIncorrectpartdataConfirmpartdataandtightenthetolerancetospecificationComponentissueComponentweightnotsuitableforbottomsidereflowDefective/uncalibratedfeederusedReplacefeederHighblowpressureCheckandreduceblowpressuretominimumIncorrectmountheightAdjustmountheightDefectivevacuumvalvesonmountinghead.CheckvacuumvalveREFLOWPURPOSEAprocessthatmeltsthesolderpasteandmakessolderjointsbetweencomponentleadsandcopperpadsonPCB.OPERATI