电路板阻抗介绍(Polar公司提供)

HowisaPCBmade?HowisaPCBmade?HowisaPCBmade?HowisaPCBmade?Whatdeterminesimpedance?Whatdeterminesimpedance?Whatdeterminesimpedance?Whatdeterminesimpedance?(Outer)Layer6(Outer)Layer2(Inner)Layer3(Inner)Layer4(Inner)Layer5(Inner)FOILFOILFOILFOILFOILFOILFOILFOILPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGPRE-PREGINNERLAYERINNERLAYERINNERLAYERINNERLAYERINNERLAYERINNERLAYERINNERLAYERINNERLAYERCopperLaminate•Layerbuild/stackupisoneofthemostimportantaspectsofcontrolledimpedance•Manycombinationsofmaterialthicknessandcopperweightscanbeused.•PCBFabricatorsmanufacturingtechniquesvaryImpedanceConsiderations4ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses––––MaterialSelectionMaterialSelectionMaterialSelectionMaterialSelectionLayer2(Inner)Layer3(Inner)CoreCoreCoreCoreCopperLaminate(Dielectric)•SelectinginnerlayerCorematerialsisveryimportantwhenusingembeddedmicrostripandoffsetstriplinestructures•InnerlayerCorematerialsareusuallyprocessedas“Layerpairs”ImpedanceConsiderations5ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses(Inner)Layer3(Inner)CoreCoreCoreCore•DoesnoteffectimpedanceImpedanceConsiderationsLaminatingandImagingofInternalLayersLaminatingandImagingofInternalLayersLaminatingandImagingofInternalLayersLaminatingandImagingofInternalLayersUVsensitivefilmislaminatedovertopandbottomUVsensitivefilmislaminatedovertopandbottomUVsensitivefilmislaminatedovertopandbottomUVsensitivefilmislaminatedovertopandbottomsurfacesoftheCoresurfacesoftheCoresurfacesoftheCoresurfacesoftheCoreAreasoftheCorewherenocopperisrequiredareAreasoftheCorewherenocopperisrequiredareAreasoftheCorewherenocopperisrequiredareAreasoftheCorewherenocopperisrequiredareleftexposedleftexposedleftexposedleftexposed6ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses•Theetchprocessproducesan‘etchback’orundercutofthetracks.ThiscanbespecifiedbytheW1/W2parameters•Thismeansthattrackswillendupapproximately0.025mm(0.001”)thinnerthantheoriginaldesign.ImpedanceConsiderationsEtchProcess-RemoveExposedCopperEtchProcess-RemoveExposedCopperEtchProcess-RemoveExposedCopperEtchProcess-RemoveExposedCopperCopperRemovedCopperRemovedCopperRemovedCopperRemovedLayer2(Inner)Layer3(Inner)7ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses•DoesnoteffectimpedanceImpedanceConsiderationsRemoveLaminatingFilmRemoveLaminatingFilmRemoveLaminatingFilmRemoveLaminatingFilmLayer2(Inner)Layer3(Inner)8ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses•DoesnoteffectimpedanceImpedanceConsiderationsCompletedInnerLayerCoreCompletedInnerLayerCoreCompletedInnerLayerCoreCompletedInnerLayerCoreLayer2(Inner)Layer3(Inner)AllinnerlayerCorematerialsareprocessedasAllinnerlayerCorematerialsareprocessedasAllinnerlayerCorematerialsareprocessedasAllinnerlayerCorematerialsareprocessedas““““LayerPairsLayerPairsLayerPairsLayerPairs””””priortoBondingpriortoBondingpriortoBondingpriortoBondingAtthisstagetheCoresareinspectedvisuallyAtthisstagetheCoresareinspectedvisuallyAtthisstagetheCoresareinspectedvisuallyAtthisstagetheCoresareinspectedvisually(AOI)anddefectiveCoresrejected(AOI)anddefectiveCoresrejected(AOI)anddefectiveCoresrejected(AOI)anddefectiveCoresrejectedSometimesasurfacetreatmentisappliedtotheSometimesasurfacetreatmentisappliedtotheSometimesasurfacetreatmentisappliedtotheSometimesasurfacetreatmentisappliedtotheCorestoaidwiththeBondingprocessCorestoaidwiththeBondingprocessCorestoaidwiththeBondingprocessCorestoaidwiththeBondingprocess9ManufacturingProcessesManufacturingProcessesManufacturingProcessesManufacturingProcesses(Outer)Layer6(Outer)Layer2(Inner)Layer3(Inner)Layer4(Inner)La