ipc-7351b表貼元件焊盤設計規(guī)范

1、IPC7351BGenericRequirementsfSurfaceMountDesignLPatternStardFINALDRAFTFINDUSTRYREVIEW–AUGUST20091SCOPEThisdocumentprovidesinfmationonlpatterngeometriesusedfthesurfaceattachmentofelectroniccomponents.Theintentoftheinfmatio

2、npresentedhereinistoprovidetheappropriatesizeshapetoleranceofsurfacemountlpatternstoinsuresufficientareaftheappropriatesolderfillettomeettherequirementsofIPCJSTD001alsotoallowfinspectiontestingrewkofthosesolderjoints.1.1

3、PurposeAlthoughinmanyinstancesthelpatterngeometriescanbedifferentbasedonthetypeofsolderingusedtoattachtheelectronicpartwhereverpossiblelpatternsaredefinedwithconsiderationtotheattachmentprocessbeingused.Designerscanuseth

4、einfmationcontainedhereintoestablishstardconfigurationsnotonlyfmanualdesignsbutalsofcomputeraideddesignsystems.Whetherpartsaremountedononebothsidesoftheprintedboardsubjectedtowavereflowothertypeofsolderingthelpatternpart

5、dimensionsshouldbeoptimizedtoinsurepropersolderjointinspectioncriteria.Lpatternsaredimensionallydefinedareapartoftheprintedboardcircuitrygeometryastheyaresubjecttotheproducibilitylevelstolerancesassociatedwithplatingetch

6、ingassemblyotherconditions.Theproducibilityaspectsalsopertaintotheuseofsoldermasktheregistrationrequiredbetweenthesoldermasktheconductpatterns.Note1:Thedimensionsusedfcomponentdeionshavebeenextractedfromstardsdevelopedby

7、industrialstardsbodies.Designersshouldrefertothesestardsfadditionalspecificcomponentpackagedimensions.Note2:Facomprehensivedeionofthegivenprintedboardfachievingthebestpossiblesolderjointstothedevicesassembledthewholeseto

8、fdesignelementsincludesbesidethelpatterndefinition:?Soldermask?Solderpastestencil?Clearancebetweenadjacentcomponents?Clearancebetweenbottomofcomponentprintedboardsurfaceifrelevant?Keepoutareasifrelevant?Suitablerulesfadh

9、esiveapplicationsThewholeofdesignelementsiscommonlydefinedas‘‘mountingconditions.’’Thisstarddefineslpatternsincludesrecommendationsfclearancesbetweenadjacentcomponentsfotherdesignelements.Note3:Elementsofthemountingcondi

10、tionsparticularlythecourtyardgiveninthisstardarerelatedtothereflowsolderingprocess.Adjustmentsfwaveothersolderingprocessesifapplicablehavetobecarriedoutbytheuser.Thismayalsoberelevantwhensolderalloysotherthaneutectictinl

11、eadsoldersareused.Note4:Thisstardassumesthatthelpatternfollowstheprinciplethatevenunderwstcaseconditionstheoverlapofthecomponentterminationthecrespondingsolderinglwillbecomplete.Note5:Heatdissipationaspectshavenotbeentak

12、enintoaccountinthisstard.Greatermassmayrequireslowerprocessspeedtoallowheattransfer.Note6:Heaviercomponents(greaterweightperl)requirelargerlsthusaddingadditionallpatternsurfacewillincreasesurfaceareaofmoltensoldertoenhan

13、cecapabilitiesofextraweight.Insomecasesthelsshowninthestardmaynotbelargeenoughinthesecasesconsideringadditionalmeasuresmaybenecessary.1.2DocumentationHierarchyThisstardidentifiesthegenericphysicaldesignprinciplesinvolved

14、inthecreationoflpatternsfsurfacemountcomponentsissupplementedbyasharewareIPC7351LPatternCalculatthatprovidesthroughtheuseofagraphicaluserinterfacetheindividualcomponentdimensionscrespondinglpatternrecommendationsbasedupo

15、nfamiliesofcomponents.TheIPC7351LPatternCalculatisprovidedonCDROMaspartofthisstard.UpdatestolpatterndimensionsincludingpatternsfnewcomponentfamiliescanbefoundontheIPC1.Exactdetailsbasedonindustrycomponentspecificationsbo

16、ardmanufacturingcomponentplacementaccuracycapabilities.TheselpatternsarerestrictedtoaspecificcomponenthaveanidentifyingIPC7351lpatternname.2.Equationscanbeusedtoalterthegiveninfmationtoachieveamerobustsolderconnectionwhe

17、nusedinparticularsituationswheretheequipmentfplacementattachmentaremelessprecisethantheassumptionsmadewhendeterminingthelpatterndetails(see3.1.2).Threelpatterngeometryvariationsaresuppliedfeachofthedevicefamiliesmaximuml

18、protrusion(DensityLevelA)medianlprotrusion(DensityLevelB)minimumlprotrusion(DensityLevelC).BefeadaptingtheminimumlpatternvariationstheusershouldconsiderproductqualificationtestingbasedontheconditionsshowninTable324.Densi

19、tyLevelA:Maximum(Most)LProtrusion–Flowdensityproductapplicationsthe‘maximum’lpatternconditionhasbeendevelopedtoaccommodatewaveflowsolderofleadlesschipdevicesleadedgullwingdevices.Thegeometryfurnishedfthesedevicesaswellas

20、inward‘‘J’’fmedleadcontactdevicefamiliesmayprovideawiderprocesswindowfreflowsolderprocessesaswell.DensityLevelB:Median(Nominal)LProtrusion–Productswithamoderatelevelofcomponentdensitymayconsideradaptingthe‘median’lpatter

21、ngeometry.Themedianlpatternsfurnishedfalldevicefamilieswillprovidearobustsolderattachmentconditionfreflowsolderprocessesshouldprovideaconditionsuitablefwavereflowsolderingofleadlesschipleadedgullwingtypedevices.DensityLe

22、velC:Minimum(Least)LProtrusion–Highcomponentdensitytypicalofptablehheldproductapplicationsmayconsiderthe‘minimum’lpatterngeometryvariation.ionoftheminimumlpatterngeometrymaynotbesuitablefallproductusecategies.Theuseofcla

23、ssesofperfmance(123)iscombinedwiththatofcomponentdensitylevels(ABC)inexplainingtheconditionofanelectronicprintedboardassembly.AsanexamplecombiningthedeionasLevels1A3B2Cwouldindicatethedifferentcombinationsofperfmancecomp

24、onentdensitytoaidinunderstingtheenvironmentthemanufacturingrequirementsofaparticularprintedboardassembly.AlthoughallthreelpatterngeometryvariationsareconsideredcompliantfleadfreesolderingprocessestheDensityLevelCvariantw

25、illrequiremeprocessingcapabilitytoensureaproperwettingoftheleadfreealloy.Itisimptanttonotehoweverthattheprimaryissueofleadfreerelatestothesurfacefinishontheprintedboardthecomponenttermination.See3.2.3ffurtherinfmationonl

26、patterndesigninleadfreesolderingenvironments.Note:ItistheresponsibilityoftheusertoverifytheSMTlpatternsusedfachievinganundisturbedmountingprocessincludingtestinganensuredreliabilityftheproductstressconditionsinuse.Inaddi

27、tionthesizeshapeoftheproposedlpatternmayvaryaccdingtothesoldermaskaperturethesizeofthelpatternextension(dogbone)theviawithintheextensioniftheviaisinthelpatternitself.Alsotheusageofoblongroundedlpatternpadsisconsideredadv

28、antageousfleadfreesolderingprocessesincomparisonwithrectangularpadsastheoblongshapeprovidesfapullofthesolderonthepad.Anexceptiontothisruleiswhentheheelptionofthelpatternhastobetrimmedduetowhenthecomponentbodystoffislesst

29、hanthepastemaskstencilthicknesstheheelhastobetrimmeddueto“ThermalPad”interference.Inthesetwocasestherectangularpadshapeispreferredtocompensatefthereductionincopperareaofthelpatternpadlength.1.5TermsDefinitionsTermsdefini

30、tionsusedhereinareinaccdancewithIPCT50exceptasotherwisespecified.Note:Anydefinitiondenotedwithanasterisk()isareprintofthetermdefinedinIPCT50.AsAgreedUponBetweenUserSupplier(AABUS)Indicatesadditionalalternaterequirementst

31、obedecidedbetweentheuserthesupplierintheprocurementdocumentation.Examplesincludecontractualrequirementsmodificationstopurchasedocumentationinfmationonthedrawing.Agreementscanbeusedtodefinetestmethodsconditionsfrequencies

32、categiesacceptancecriteriawithinatestifnotalreadyestablished.Assembly–Anumberofpartssubassembliescombinationsthereofjoinedtogether.(Note:Thistermcanbeusedinconjunctionwithothertermslistedhereine.g.‘‘PrintedBoardAssembly.