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1、PCB各层的作用Theworklayercanbebroadlydividedinto7categories:Signal,Layers(signallayer),InternalPlanes(internalpower/groundlayer),MechanicalLayers(mechanicallayer),Masks(soldermask),Silkscreen(SiYinceng),Others(otherworklevel)andSystem(systemworklayer)・1.SignalLayers(signallayer)Itincludes[To
2、pLayer](toplayer),[BottomLayer](bottom),[MidLayerl](intermediatelayer1)and[MidLayer2](intermediatelayer2)[MidLayer30](middlelayer30).Thesignallayerisusedprimarilyforplacementofcomponents(topandbottom)androuting・Thesignallayerispositive,i.e.,attheseoperatinglayersThewiresorotherobjectspl
3、acedonthesurfaceareareascoveredwithcopper・2.InternalPlanes(internalpower/groundlayer)Internalpower/groundlayer(referredtoasinnerlayer):[InternalPlane]],theselevelsofworkarededicatedtothearrangementofpowerlinesandgroundwires・Thelinesorotherobjectsplacedattheselevelsarecopperfreeregions,i
4、・e.,theselayersarenegative・Eachinternalpower/groundcangiveanelectricalnetworkname,printedcircuitboardeditorautomaticallythelevelandtheotherwiththesamenetworkname(i.e.electricalconnectionpads),connectedtotheformofprepull.Alsoallowstheinternalpower/groundlayertobecutintomultiplesublayers,
5、thatis,eachinternalpower/groundlayermayhavetwoormorepowersupplies,suchas+5Vand+15V,andsoforth・Two.3.MechanicalLayers(mechanicallayer)Themechanicallayerisgenerallyusedtoplaceindicativeinformationabouttheboardandassemblymethods,suchascircuitboards,physicaldimensionlines,dimensionalmarking
6、s,datadata,through-holeinfomiation,assemblyinstructions,etc.・4.Masks(soldermask,solderpasteprotectionlayer)Solderresist:[Top,Solder](topsolderbarrier)and(Bottom,Solder])・Thesolderresistisnegativeandthepadsorotherobjectsplacedonthelayerareareaswithoutcopper・Usually,inordertomeettherequir
7、ementsofmanufacturingtolerances,themanufactureroftenrequiresspecifyingabarrierextensionruletoenlargethesolderresistlayer・Fordifferentrequirementsofdifferentpads,multiplerulescanbesetinthesolderresistlayer・Thesolderpasteprotectivelayersare[TopPaste](toplayersolderpasteprotection
