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1、IPC-7351BGenericRequirementsforSurfaceMountDesignandLandPatternStandardFINALDRAFTFORINDUSTRYREVIEW–AUGUST20091SCOPEThisdocumentprovidesinformationonlandpatterngeometriesusedforthesurfaceattachmentofelectroniccomponents.Theintentoftheinformationpresentedher
2、einistoprovidetheappropriatesize,shapeandtoleranceofsurfacemountlandpatternstoinsuresufficientareafortheappropriatesolderfillettomeettherequirementsofIPCJ-STD-001,andalsotoallowforinspection,testing,andreworkofthosesolderjoints.1.1PurposeAlthough,inmanyinst
3、ances,thelandpatterngeometriescanbedifferentbasedonthetypeofsolderingusedtoattachtheelectronicpart,whereverpossible,landpatternsaredefinedwithconsiderationtotheattachmentprocessbeingused.Designerscanusetheinformationcontainedhereintoestablishstandardconfigur
4、ationsnotonlyformanualdesignsbutalsoforcomputer-aideddesignsystems.Whetherpartsaremountedononeorbothsidesoftheprintedboard,subjectedtowave,reflow,orothertypeofsoldering,thelandpatternandpartdimensionsshouldbeoptimizedtoinsurepropersolderjointandinspectioncr
5、iteria.Landpatternsaredimensionallydefinedandareapartoftheprintedboardcircuitrygeometry,astheyaresubjecttotheproducibilitylevelsandtolerancesassociatedwithplating,etching,assemblyorotherconditions.Theproducibilityaspectsalsopertaintotheuseofsoldermaskandthe
6、registrationrequiredbetweenthesoldermaskandtheconductorpatterns.Note1:Thedimensionsusedforcomponentdescriptionshavebeenextractedfromstandardsdevelopedbyindustrialand/orstandardsbodies.Designersshouldrefertothesestandardsforadditionalorspecificcomponentpacka
7、gedimensions.Note2:Foracomprehensivedescriptionofthegivenprintedboardandforachievingthebestpossiblesolderjointstothedevicesassembled,thewholesetofdesignelementsincludes,besidethelandpatterndefinition:•Soldermask•Solderpastestencil•Clearancebetweenadjacentco
8、mponents•Clearancebetweenbottomofcomponentandprintedboardsurface,ifrelevant•Keepoutareas,ifrelevant•SuitablerulesforadhesiveapplicationsThewholeofdesignelementsiscommonlydefinedas‘‘mountingconditions.’’Thissta
