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1、ConformalCoatingKnowledgeHorryTian2010/09/14WhatisConformalCoating?PerIPC-T-050,page22Itisaninsulatingprotectivecoveringthatconformstotheconfigurationoftheobjectscoated,providingaprotectivebarrieragainstdeleteriouseffectsfromenvironmentalconditions.CAreTh
2、ereDifferentTypes?Therearefivetypes:AR-AcrylicResinER-EpoxyResinUR-UrethaneResinSR-SiliconeResinXY-ParaxylyleneResinorParyleneResinAcrylicResin•Acrylicresinconformalcoatingsareperhapsthemostpopularofallconformalcoatingsduetotheireaseofapplication,removal,
3、andforgivingnature.•Easytoworkwithforcomponentremoval.Epoxy•Epoxiesareveryhard,usuallyopaque,andgoodatresistingtheeffectsofmoisture.•Difficult,ifalmostimpossible,toremovewithoutdamagingcomponents.Urethane•Thesecoatingsaretough,hard,andexhibitexcellentresi
4、stancetosolvents.•Theyhavelimitedhightemperaturecapability,andaninabilitytoberepairedoftenpreventstheiruse.SiliconeResin•Silicones(typeSR)aretypicallyusedinhigh-temperatureenvironments.•Siliconecoatingsareeasytoapply,havelowtoxicity,offergoodresistancetom
5、oisture,abrasion,andhumidity,andareusefuloverawidetemperaturerange.•Althoughtheirdielectricstrengthislessthanothertypesofcoatings,theeaseofapplicationandexcellentadhesiontopreviouslyappliedcoatingsallowsforthebuildupofathickerfilmandimproveddielectricstre
6、ngth.ParaxylyleneorParylene•Excellentcoverageanduniform•Highcost,sensitivetocontaminants,andneedvacuumapplication.ApplicationMethodsUsualapplicationmethodsare:•Dipping•Spraying•Flowcoating•VacuumapplicationUses•Mechanicalprotection•Corrosionprevention•Min
7、imizedendriticgrowthonPWA•ImprovesinsulationresistancebetweencircuitsDoesItHavetoCoverEverything?•No,applyittoareaswhereitneedstobeapplied,butkeepitoffareaswhereadditionalconnectionstotheproductwillbemade.•Keepitoutofunsealedcomponents•Therefore,per001D,p
8、age38:“Coveronlythoseareasspecifiedontheassemblydrawing/documentation.”J-STD-001&610AcceptanceCriteria•J-STD-001D,par.10.1.2.2CoatingCoverage•IPC-A-610,10.5.2ConformalCoatingTargetCondition-Class1,2,3Acceptable-Clas
