三防漆与灌封.ppt

electronicmoduleconformalcoatingandpotting mpc t 1 2 trainingobjectives explainwhatcoatingsandpottingsareandwhytheyareuseddescribecoatingandpottingapplicationmethodsandcontrolsprovideexamplesofcoatingandpottingwithindelphiprovideresourcesforadditionalinformation 3 outline definitionscoatingreasonsforcoatingmaterialtypesapplicationmethodsanddelphiexamplesqualityissuespottingreasonsforpottingmaterialtypesapplicationmethodsanddelphiexamplesqualityissuesadditionalsourcesofinformation 4 whatisit conformalcoatingathinlayerofadielectric electricallyinsulating chemicalcompoundthatisappliedtothesurfaceandservestoprotecttheelectroniccircuitry thematerialcanbetransparentoropaque potting alsoreferredtoasencapsulation aprocessoffillingacompleteelectronicassemblywithasolidcompoundforresistancetoshockandvibration andforexclusionofmoistureandcorrosiveagents transparentcoatingonapopulatedprintedcircuitboard opaquepottingmaterialinanelectronicmodulecavity transparent gel pottingmaterialinanelectronicmodulecavity 5 additionaldefinitions ion anatomormoleculewherethetotalnumberofelectronsisnotequaltothetotalnumberofprotons givingitanetpositiveornegativeelectricalcharge ioniccontamination surfacedebristhatcontainsionselectrochemicalmigration ecm alsoknownasdendriticgrowth isthegrowthofconductivemetalfilamentsonorinaprintedcircuitboard pcb undertheinfluenceofadcvoltagebias thefilamentgrowthisfacilitatedbythemovementofionsonthecircuitboard tinwhiskers acrystallinemetallurgicalphenomenoninvolvingthespontaneousgrowthoftiny filiformhairsfromametallicsurface themechanismisencouragedbycompressivemechanicalstressessilicone inert man madepolymercompoundsthatincludesilicon carbon hydrogenandoxygenandsomeotherchemicalelements siliconescanbeusedoverawidetemperaturerange acrylic thermoplasticmadebypolymerizingacrylicacidormethacrylicacid acrylicsareusedforcastandmoldedpartsorascoatingsandadhesivespolyurethane anypolymerconsistingofachainoforganicunitsjoinedbyurethane carbamate linkspolyurethaneformulationscoveranextremelywiderangeofstiffness hardness anddensities coatings 7 whydowecoat encapsulateandimmobilizeioniccontaminationpreventelectrochemicalmigration ecm alsoknownasdendriticgrowthpreventfurthercontaminationofcircuitrybyenvironmentalsalts soils dust smoke andwatervaporpreventcircuitleakagebetweenconductorsandpossiblearcinginhighcurrentsituationsforexampletheul94v0standardrequirethatcoatingssurvive1000vforoneminutewithoutbreakdownatminimalcoatingthicknessafterprescribedthermalconditioningprovidephysicalprotectiontothecircuitryandcomponentsbypreventingsurfacescratchesundernormalhandlingandusemitigatetheeffectoftinwhiskers 8 encapsulatingcontaminants thinlayerofwaterorwatervapor varioustypesofcontamination circuitboardlaminate withoutconformalcoating thinlayerofwaterorwatervapor conformalcoatingkeepsmoistureawayandencapsulatescontaminationandcircuitry contaminantsdissolveinwaterandbecomemobileions 9 whatisdendriticgrowth itisaformof electro chemicalmigration ecm conductivemetalfilamentsgrowonthesurfaceofaprintedwiringboard pwb orcomponentundertheinfluenceofadcvoltagebiasecm ordendriticgrowth isverysimilartoelectro plating metallicionsmigratefromtheanode tothecathode ofacircuitundertheinfluenceofanelectricalbiasandinthepresenceofsufficientwaterorotherelectrolyte imagefromwww npl co uk directionofgrowth 10 whatisdendriticgrowth electricity water contamination dendrites 11 dendriticgrowth conditionsforelectrochemicalmigrationanelectricalpotential voltage betweentheelectrodesisneededtoestablishanioniccurrentinthewaterlayer waterorotherelectrolytemustbepresenttodissolvetheionicmaterialsandsustainthemintheirmobileionicstate electricalcarriers suchasions mustbepresent 1 biasispresent 1to2volts 2 waterispresent 3 ioniccontaminationispresent thereforedendriticgrowth 12 dendriticgrowth appliedcorrectly conformalcoatingwillpreventelectro chemicalmigration providesadditionaldielectricmaterialtoreducetheelectricalpotential voltage betweentheelectrodescreatesabarrierbetweenwaterorotherelectrolyteandioniccontaminantssothationsarenotdissolved 1 biasispresent 1to2volts 2 waterispresent 3 ioniccontaminationcannotdissolveandbecomemobileions thereforenodendriticgrowth 13 dendriticgrowth acautionarynote conformalcoatingisnotabarriertostandingwaterovertimewatermoleculeswillpenetratesiliconeandacryliccoatingswhenthecoatingisthinwatermigratestothesurfacerelativelyquicklysmallchipcapacitorshavebeenshowntobeverysensitivetothiscondition verificationofcoatingcoverageandthicknessduringprocessset upiscritical dendriteacrosscapacitorterminalswherecoatingisthin missing 14 anothercasewherecoatingdoesnothelp circuitboardlaminate contaminationbridgescircuitry coatinglayer continuouscontaminationlayerisinplacepriortocoatingapplication 15 istheproductinasealedcase potted orgelencapsulated coatingrecommendedbymtt productremainsuncoated istheproductamissioncriticalorsafetyrelateddevice tryvalidatingwithnoconformalcoating productpassesvalidationwithnoecm productfailsvalidation tryvalidatingwithnoconformalcoating doestheproducthavepure 99 tinfinishesonthecircuitboardoranycomponentsurface includingconnectors surfacemountcomponentsandthroughholecomponents conformalcoatingrecommended failureduetocauseotherthanecmormoisturesusceptibility failureduetoecm corrosion moisturesusceptibility validationrequirescondensingmoisturewhileunderpowerora dewingtest productpassesvalidationwithnoecm productremainsuncoated productfailsvalidationduetoecm corrosion moisturesusceptibility mttrecommendedcoat no coatdecisiontree customerrequirescoatingregardlessofcasedesign mfgerp9 3appendixa 16 keycoatingdecisionfactors customerrequirementspecificallyrequiredregardlessofproductdesignortechnologybuild to printvalidationtestspecificationsproductdesignandapplicationrequirementsliquidwatercondensingoncircuitsgenerallydrivesthedecisiontocoatresultofproductvalidationafunctionofproductusageorlocationsealedcasedesigntypicallydoesnotrequirecoatingpoorcomponentorboardcleanlinessorexessivewaterabsorptiondrivesneedtocoathighfailuremode severity canbemitigatedbycoatingcircuitboardinallcasesmfgerp9 12 liquidwaterimmunitytestcanbeusedtoidentifysensitivecircuitrythatwillrequirecoating 17 whatcoatingmaterialsareused delphi e s scurrentmenuofconformalcoatingshasselectionsfrommostcoatingtypes commonlyusedsilicones5approvedmaterialsavailableacrylic1approvedmaterialapplicationspecificmaterialspolyurethanetypicallyusedineuropeparylenemustbeappliedbya3rdparty singlesource beforeuse materialsmustpasscomprehensivecompatibilitytesting includingsurfaceinsulationresistance andsolderjointreliabilitytestingmfgerp 9 21definesthetestplanandmethodsmaterialscoe hanksanftleben mustapproveusage 18 siliconecoatingmaterials silicone anentirelysyntheticpolymercontainingasi obackbone organicgroupsarefrequentlyattachedtothebackboneviaasi cbondnote siliconisametalandsiliconeisapolymeradvantageswidetemperaturerange complianttomostenvironmentalrestrictions weee rohs reach lowmechanicalstressconcernscustomersensitivitytosiliconecontaminationsomerelaysandbrushmotorsaresensitivetosiliconevolitilesonlywhensiliconeiswithin1cmorsoofthearccurrentonlyonrelayswithpoorlysealedhousingsmaterialsuppliersdowcorningshinetsu materialhightempflexibletosilicones 150to200 c 45to 115 cepoxies 150to180 cn aurethanes 115to125 c 60 cacrylics 85 cn a 19 acryliccoatingmaterials acrylicresin thermoplasticorthermosettingplasticsubstancederivedfromacrylicacid methacrylicacidorotherrelatedcompoundsadvantagesnoriskofsiliconevolitilesfastambientcuringcapableofapplyingverythinlayer 0 001 concernsnotapprovedforhightemperatureapplicationsmaxtemp 85csolventbased thereforemaynotsatisfyreachrequirementsnotalowvoc volitileorganiccompounds materialmaterialsupplierselantas pdgeorge 20 polyurethanecoatingmaterials polyurethane afamilyofpolymersthatofferarangeofhardnessvalues theyhavegoodstrengthandenvironmentalresistancepropertiesadvantages2 partcuringsystemscanbeadjustedforapplicationvarycatalysttoresinratiotomodifyhardnessgoodmoistureresistanceconcernslimitedservicetemperature 120c noteasilyrepairedsuppliersprimarilysuppliedtoeuropeanmanufacturingsiteslackwerkepetershunstman 21 coatingapplicationmethods lean selectivespraycoatingalsohavejetpulseprecisioncoatingdipcoatingdispensecoatingonlyapprovedforuseinspecializedcasesmanualbrushcoatingnotrecommendedbythemttforgeneraluse 22 spraycoating thepreferredmethodforapplyingconformalcoatingsinmanufacturingsprayheadsaremountedon3 axisrobotgantries thesystemhasnaturaltolerancesandcapabilitylimitations selectivecoatingsprayvalves spraycoater 23 spraycoatingdetails exampleofusagepvaequipmentsprayingdc3 1953 siliconecoating kokomoplant7 bcmforgmt900truckdelnorte multipleprograms nordson asymtekequipmentsprayingpdgeorge5026 21 acryliccoating delnorte ddm szm multipleprograms siliconecoatingcanbeappliedbybothsystemsacryliccoatingisbestappliedbynordson asymteksystemwhyused preferredcontrolledapplicationofcoatingreducedmaterialandutilityusagefits lean principlespreventmaterialfromcoating keep out zoneswithoutmaskingreducedboardtoboardcross contaminationcommonissuesnozzlecloggingthicknessvariationorstreakingoversprayintokeep outareasshadowingaroundlargercomponents 24 precisionspraycoating alsoknownasjetpulsespraycoatingspecialapplicationofselectivespraycoatingwhentighterspraytoleranceisrequiredstandardclearancetonon coatedareasis3 2mmprecisioncoatingclearanceis1 0mm 25 dipcoating boardisdippedinabathofcoatingexampleofusagesuzhouequipment chenghuamaterial dc4097 silicone delnorteequipment knoedel paintlinematerial dc4097 silicone equipmentdifferencesknoedelsystemraisesasmalltubofcoatingtotheboardpaintlineandchenghuasystemsbringboardsdowntoalargertubofcoating 26 dipcoating whyusedapplycoatingquicklyacrossanentireboardfloodsareaswheresmallcomponentsmayresideunderconnectionsystemeconomicalforhighvolumeproductioncommonissueskeep outareasmustbemaskedcoatingindipbathcanbecomecontaminatedwithfluxorotherresiduesdc4097neutralizesfluxresiduessolventbornecoatingiseffectedbyfluxneedtomonitorandpreventviscositychangesinthebathfordc4097 atleast20 ofthematerialmustbeusedorreplacedperweekifsolventbornecoating needtoaddsolventtomaintainviscositydrawbackslargeequipmentsizenotscalableforlowervolumecannotdipcoatwithnon underfilledbgasunderfilledflip chipsareok 27 cureprocesses dependingontheirchemistry coatingscanbecuredbyheatuvenergymoistureambientair 28 coatingguidelines dds27definestheminimumclearancebetween mustbe coatedand mustnotbe coatedareasis3 2mmallowsforsomeslumporoversprayaroundcoatedareasfrommfgerp9 9coatingthicknessguidelinesforcircuitboardenvironmentwithcondensingmoisture 29 quality qualitydefectsareidentifiedbytheireffectonadhesion coverage orcoatinghomogeneitydoesitcompromisethecoating sabilitytoprotectthecircuit doesitcompromisedownstreamoperations examples alwaysrefertoreleasedproductworkmanshipstandardsforspecificcriteria bubbleexposespcb excessivebubbling insufficientcoverage overspray 30 quality ipc610distheprimarysourceforcoatingqualityadditionalqualityguidelinesavailablethroughthecoatingsandadhesivewebpage 31 quality theadditionofuvdyetothecoatingsmakesdefectseasilyvisibleunderablacklight 32 assemblystackingerrorassemblyslidingonworksurfaceerror boththecoatingandthecomponentscanbedamagedbymishandling assemblyhandlingerrors pottings 34 whyusepotting encapsulateandimmobilizeioniccontaminationprovidephysicalprotectiontothecircuitryandcomponentswithoutneedforacoverprovidemechanicalstabilitytocomponentswithrespecttovibrationandshock 35 whatpottingmaterialsareused siliconebasedgelshardpottingepoxypolyurethanesiliconeadhesives 36 selectingapottingmaterial beforeuse materialsmustpasscomprehensivecompatibilitytesting includingsurfaceinsulationresistance andsolderjointreliabilitytestingrp 9 21definesthetestplanandmethodsmaterialscoeapprovalrequiredinaddition pottingsmustmeetthermalandmechanicalrequirementsfortheproductcannotimpartundothermalstressoncomponentsshouldnotcreateexcessvoidsorexpansionwithinaconstrainedspace 37 cureprocesses pottingsareappliedtoproductsby1 partor2 partdispense1 partmaterialsheatmoistureoxidation2 partmaterialswillgenerallycureuponmixingcantake24hoursormoreforfullcureadditionalminimumholdtimemayberequiredbeforevalidationtestinguptoseveraldaysprocesscanbeacceleratedbyheatsystempurgeandfrequentchangeofmixtubesisrequiredtopreventcloggingmaterialmixingcanbedone statically or dynamically 38 2 partmixingtechniques staticmixingmaterialiscombinedasitflowsthroughaspeciallydesignedmixtubedynamicmixingmixingequipmentusesmovingpartstocombinethepottingcomponentspriortodispensing 39 productexample sdmfluidresearchequipmentdispensespdgeorgeuh510stwoparturethane 40 quality uvdyeinatransparentgelcanmakeitvisibleforautomatederrorproofingsomelevelofbubblingistobeexpectedairescapesfromunderlargecomponentssomeairentrappedinprocessexcessivebubblingandfoamingcanoccurifmaterialchange overnotcompletedproperlysampleworkmanshipstandard 41 badproductpottingdesign partialfillofan invertedcup willapplyexcessivestressonsolderjointsgelshrinksduringcooldownaftercuresoldercrackingoccurredatt 0 42 summary coatingsorpottingsarerequiredfortheelectricalandmechanicalprotectionofmanyautomotiveelectroniccircuitboardsthereareanumberofmttapprovedmaterialsthatareappliedbyavarietyofmethodscontactthemttifnewmaterialsarebeingconsideredforapplicationvisitthecoatingsandadhesivesmttwebpagetolearnmoreabouttheapplicationbuildingblocks link 43 howtoaccesthemttwebpage 44 howtoaccessthemttwebpage 45 howtoaccessthemttwebpage 46 quizquestions 47 question1 water contamination dendrites 48 question1 electricity water contamination dendrites 49 question2 conformalcoatingprovidesawatertightsealforelectronicstruefalse 50 question2 conformalcoatingprovidesawatertightsealforelectronicstruefalseconformalcoatingisnotabarriertostandingwaterovertimewatermoleculeswillpenetratesiliconeandacryliccoatingswhenthecoatingisthinwatermigratestothesurfacerelativelyqui