ASTM B 488-2001 R2006

Designation:B488–01(Reapproved2006)StandardSpecificationforElectrodepositedCoatingsofGoldforEngineeringUses1ThisstandardisissuedunderthefixeddesignationB488;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope1.1Thisspecificationcoversrequirementsforelectrodepos-itedgoldcoatingsthatcontainnotlessthan99.00mass%goldandthatareusedforengineeringapplications.1.2Specificallyexcludedfromthisspecificationareauto-catalytic,immersion,andvapordepositedgoldcoatings.1.3Goldcoatingsconformingtothisspecificationareem-ployedfortheircorrosionandtarnishresistance(includingresistancetofrettingcorrosionandcatalyticpolymerization),bondability,lowandstablecontactresistance,solderability,andinfraredreflectivity.Severaltypesofcoatings,differingingoldpurityandhardness,arecoveredbythisspecification.1.4ThevaluesstatedinSIunitsaretoberegardedasthestandard.Valuesprovidedinparenthesesareforinformationonly.1.5Thefollowinghazardscaveatpertainsonlytothetestmethodssection,Section9,ofthisspecification:Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2B183PracticeforPreparationofLow-CarbonSteelforElectroplatingB242GuideforPreparationofHigh-CarbonSteelforElectroplatingB253GuideforPreparationofAluminumAlloysforElec-troplatingB254PracticeforPreparationofandElectroplatingonStainlessSteelB281PracticeforPreparationofCopperandCopper-BaseAlloysforElectroplatingandConversionCoatingsB322GuideforCleaningMetalsPriortoElectroplatingB343PracticeforPreparationofNickelforElectroplatingwithNickelB374TerminologyRelatingtoElectroplatingB481PracticeforPreparationofTitaniumandTitaniumAlloysforElectroplatingB482PracticeforPreparationofTungstenandTungstenAlloysforElectroplatingB487TestMethodforMeasurementofMetalandOxideCoatingThicknessbyMicroscopicalExaminationofaCrossSectionB489PracticeforBendTestforDuctilityofElectrodepos-itedandAutocatalyticallyDepositedMetalCoatingsonMetalsB499TestMethodforMeasurementofCoatingThick-nessesbytheMagneticMethod:NonmagneticCoatingsonMagneticBasisMetalsB504TestMethodforMeasurementofThicknessofMe-tallicCoatingsbytheCoulometricMethodB507PracticeforDesignofArticlestoBeElectroplatedonRacksB542TerminologyRelatingtoElectricalContactsandTheirUseB558PracticeforPreparationofNickelAlloysforElectro-platingB567TestMethodforMeasurementofCoatingThicknessbytheBetaBackscatterMethodB568TestMethodforMeasurementofCoatingThicknessbyX-RaySpectrometryB571PracticeforQualitativeAdhesionTestingofMetallicCoatingsB578TestMethodforMicrohardnessofElectroplatedCoatingsB602TestMethodforAttributeSamplingofMetallicandInorganicCoatingsB678TestMethodforSolderabilityofMetallic-CoatedProducts1ThisspecificationisunderthejurisdictionofASTMCommitteeB08onMetallicandInorganicCoatingsandisthedirectresponsibilityofSubcommitteeB08.08onMetallicCoatings.CurrenteditionapprovedApril1,2006.PublishedApril2006.Originallyapprovedin1968.Lastpreviouseditionapprovedin2001asB488–01e1.2ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.1Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.CopyrightbyASTMInt'l(allrightsreserved);ReproductionauthorizedperLicenseAgreementwithMoniqueTyree(ASTMIHSAccount);MonApr2413:21:14EDT2006CopyrightASTMInternationalProvidedbyIHSunderlicensewithASTMLicensee=DefenseSupplyCtr/5913977001NotforResale,01/10/200820:55:28MSTNoreproductionornetworkingpermittedwithoutlicensefromIHS--`,,`````,`,,`,``,,,,,````-`-`,,`,,`,`,,`---B697GuideforSelectionofSamplingPlansforInspectionofElectrodepositedMetallicandInorganicCoatingsB735TestMethodforPorosityinGoldCoatingsonMetalSubstratesbyNitricAcidVaporB741TestMethodforPorosityInGoldCoatingsOnMetalSubstratesByPaperElectrography3B748TestMethodforMeasurementofThicknessofMe-tallicCoatingsbyMeasurementofCrossSectionwithaScanningElectronMicroscopeB762TestMethodofVariablesSamplingofMetallicandInorganicCoatingsB765GuideforSelectionofPorosityandGrossDefectTestsforElectrodepositsandRelatedMetallicCoatingsB799TestMethodforPorosityinGoldandPalladiumCoatingsbySulfurousAcid/Sulfur-DioxideVaporB809TestMethodforPorosityinMetallicCoatingsbyHumidSulfurVapor(“Flowers-of-Sulfur”)D1125TestMethodsforElectricalConductivityandRe-sistivityofWaterD3951PracticeforCommercialPackagingF390TestMethodforSheetResistanceofThinMetallicFilmsWithaCollinearFour-ProbeArray2.2U.S.GovernmentStandards:4MIL-G-45204GoldPlating,ElectrodepositedMIL-STD-1916DODPreferredMethodsforAcceptanceofProduct2.3ANSI/ASQCStandard:5ANSI/ASQCZ1.4-1993SamplingProceduresandTablesforInspectionbyAttributes3.Terminology3.1Definitions—Fordefinitionsoftermsusedinthisspeci-ficationrefertoTerminologiesB374orB542.3.2DefinitionsofTermsSpecifictoThisStandard:3.2.1significantsurfaces—definedasthosenormallyvis-ible(directlyorbyreflection)oressentialtotheserviceabilityorfunctionofthearticle.Canbethesourceofcorrosionproductsortarnishfilmsthatinterferewiththefunctionordesirableappearanceofthearticle.Thesignificantsurfacesshallbeindicatedonthedrawingsofthepartsorbytheprovisionofsuitablymarkedsamples.3.2.2underplating—ametalliccoatinglayerbetweenthebasismetalorsubstrateandthetopmostmetalliccoating.Thethicknessofanunderplatingisusuallygreaterthan1µm(40µin.),incontrasttoastrikeorflash,whichisthinner.4.Classification4.1TypesofCoatings—Acoatingshallbespecifiedbyacombinationofthefollowing:4.1.1Type,characterizingminimumpurityinaccordancewith4.2.1,4.1.2Code,designatingKnoophardnessinaccordancewith4.2.3,and4.1.3anumeraldesignatingthicknessinmicrometresinaccordancewith4.3.4.2PurityandHardness:4.2.1Purity—TheissueofthisstandardestablishesanewASTMTypedesignation,whichisidenticaltotheoriginalstandard(MILG-45204),establishedforelectrodepositedgoldandisoutlinedinthefollowingtable.MassPercentGold,Minimum,ExcludingPotassium,Carbon&NitrogenNewASTMTypeMIL-G45204TypeOldASTMType99.70II299.00IIII399.90IIIIII1NOTE1—Itiscommonlyacceptedthatagoldpurityof99.7%isdefinedasnomorethan0.3%oftotalcodepositedmetalliccomponents,excludingpotassiumandsodium.Likewise,99.9%purityisrecognizedtomeannomorethan0.1%oftotalcodepositedmetalimpurities,excludingpotassiumandsodium.Almostallgoldelectrodepositswillcontainpotassium,carbonandnitrogenthatareoccludedorprecipitatedinthedeposit.InthecaseofTypeIgold,theoccludedpotassiumhasbeenshowntoimprovedurabilityandisdesirableforthatreason.6,74.2.2Goldpurityiscalculatedbysubtractionofthesumofallnon-goldmetalsinmass%,excludingpotassiumandsodium,from100%.ThepresenceofC,N,H,Na,andKcontainedintheelectrodepositarenotincludedinthecalcu-lation.4.2.3Hardness—HardnessvaluesshallbespecifiedbyASTMcode.Themilitarystandarddesignationofgradeisincludedforreference.KnoopHardnessRangeASTMCodeMIL-G-4520490HK25maximumAA91–129HK25BB90–200HK25(seeNote2)...130–200HK25CC>200HK25DDNOTE2—ASTMCodeBhaspreviouslybeenspecifiedforhardnessgrade90–200.Thishardnessgradehasbeeneliminatedandreplacedwithhardnessgrade91–129inaccordancewithMIL-G-45204.4.2.4RelationshipBetweenPurityandHardness—Thefol-lowingcombinationsofpurityandhardnessrangesarerepre-sentativeofgoodcommercialpractice:NewASTMOldASTMTypeCodeI2A,BandCII3B,CandDIII1Aonly4.3Thickness—ThicknessshallbespecifiedbyanArabicnumeralthatdesignatestheminimumlinearthicknessinmicrometres.ExamplesofcommonlyspecifiedthicknessesareshowninTable1.4.3.1See7.4.2forthicknesstolerances.4.3.2Insteadofspecifyingthethicknessinmicrometres,thepurchasermayspecifythemassofgoldperunitarea(coatingweight)inmilligramspersquarecentimeter.Unlessotherwisespecified,thedensityofgoldisassumedtobe19.3g/cm3forTypeIIIand17.5g/cm3forTypeIandTypeII.NOTE3—ThedensityofTypeIIIgoldcoatingswillbelessthanor3Withdrawn.4AvailablefromStandardizationDocumentsOrderDesk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Philadelphia,PA19111-5098.5AvailablefromAmericanNationalStandardsInstitute(ANSI),25W.43rdSt.,4thFloor,NewYork,NY10036.6Whitlaw,K.J.,Souter,J.W.,Trans.Inst.MetalFin.,“TheRoleofCodepositedElementsinGoldPlatedContacts,”1984,62(1),pp.29–31.7Whitlaw,K.J.,Souter,J.,Wright,I.S.,Nottingham,M.,ElectricalContacts,“WearPropertiesofHighSpeedGoldElectrodeposits,”(1984),30th.pp.33–45.B488–01(2006)2CopyrightbyASTMInt'l(allrightsreserved);ReproductionauthorizedperLicenseAgreementwithMoniqueTyree(ASTMIHSAccount);MonApr2413:21:14EDT2006CopyrightASTMInternationalProvidedbyIHSunderlicensewithASTMLicensee=DefenseSupplyCtr/5913977001NotforResale,01/10/200820:55:28MSTNoreproductionornetworkingpermittedwithoutlicensefromIHS--`,,`````,`,,`,``,,,,,````-`-`,,`,,`,`,,`---equalto19.3g/cm3,butnotlessthan18.5g/cm3.NOTE4—Whensignificantsurfacesareinvolvedonwhichthespecifiedthicknessofdepositcannotreadilybecontrolled,suchasthreads,holes,deeprecesses,basesofangles,andsimilarareas,thepurchaserandthemanufacturershouldrecognizethenecessityforeitherthickerdepositsonthemoreaccessiblesurfacesorforspecialracking.Specialracksmayinvolvetheuseofconforming,auxiliary,bipolarelectrodes,ornoncon-ductingshields.5.OrderingInformation5.1Tomaketheapplicationofthisstandardcomplete,thepurchaserneedstosupplythefollowinginformationtothesellerinthepurchaseorderorothergoverningdocument.5.1.1Thename,designation,anddateofissueofthisspecification.5.1.2Classification:type,code,andthickness(ormassperunitarea)(seeSection4).5.1.3Presenceandthicknessofunderplating,ifrequired(see3.2.2).5.1.4Significantsurfacesshallbespecified(see3.2.1).5.1.5Requirement,ifany,forperformancetestingsuchasporositytesting(see9.6),solderabilitytesting(seeAppendixX4),ductilitytesting(see9.7),etc.5.1.6Ifthesubstrateisonethatrequiresanickelunderplat-ing(see6.5.1andAppendixX6).5.1.7Whetherornotstressreliefhasbeenoristobedone(steelpartsonly).5.1.8Samplingplanemployed(seeSection8).6.Manufacture6.1Anyprocessthatprovidesanelectrodepositcapableofmeetingthespecifiedrequirementsisacceptable.6.2Substrate:6.2.1Thesurfaceconditionofthebasismetalshouldbespecifiedandshouldmeetthisspecificationpriortotheplatingoftheparts.6.2.2Defectsinthesurfaceofthebasismetalsuchasscratches,porosity,pits,inclusions,rollanddiemarks,laps,cracks,burrs,coldshuts,androughnessmayadverselyaffecttheappearanceandperformanceofthedeposit,despitetheobservanceofthebestplatingpractice.Anysuchdefectsonsignificantsurfacesshallbebroughttotheattentionofthepurchaser.6.2.3Thebasismetalshallbesubjecttosuchcleaningproceduresasarenecessarytoensureasatisfactorysurfaceforsubsequentelectroplating(seePracticesB183,B242,GuideB253,PracticesB254,B281,B322,B343,B481,B482,andB558).6.2.4Properpreparatoryproceduresandthoroughcleaningofthebasismetalareessentialforsatisfactoryadhesionandperformanceofthesecoatings.Thesurfacemustbechemicallycleanandcontinuouslyconductive,thatis,withoutinclusionsorothercontaminants.Theymustbesmoothandasfreeofscratches,gouges,nicks,andsimilarimperfectionsaspossible.NOTE5—Ametalfinishercanoftenremovedefectsthroughspecialtreatmentssuchasgrinding,polishing,abrasiveblasting,chemicaltreat-ments,andelectropolishing.However,thesemaynotbenormalinthetreatmentstepsprecedingtheplatingandaspecialagreementisindicated.6.3Ifrequired(see5.1.7),steelpartswithahardnessgreaterthan31HRCshallbegivenasuitablestressreliefheattreatmentpriortoplating.Suchstressreliefshallnotreducethehardnesstoavaluebelowthespecifiedminimum.Acidpicklingofhighstrengthsteelsshallbeavoided.6.3.1Thecoatingshallbeappliedafterallbasismetalheattreatmentsandmechanicaloperationsonsignificantsurfaceshavebeencompleted.6.4Racking—Partsshouldbepositionedsoastoallowfreecirculationofsolutionoverallsurfaces.Thelocationofrackorwiremarksinthecoatingshallbeagreeduponbetweentheproducerandthesupplier.6.5PlatingProcess:6.5.1NickelUnderplating—Forthicknessclassesexcept5.0,anickelunderplatingshallbeappliedbeforethegoldcoatingwhentheproductismadefromcopperorcopperalloy.Nickelunderplatingsarealsoappliedforotherreasons(seeAppendixX6).NOTE6—Whenthethicknessofthenickelunderplatehasadetrimentalimpactonthemechanicalpropertiesorbondabilityofthesubstrate,thenickelthicknessmaybereducedtoanon-detrimentallevelasspecifiedbythepurchaser.NOTE7—Incertaininstancesinwhichhigh-frequencyanalogsignalsareemployed,suchasinwaveguides,themagneticpropertiesofnickelmayattenuatethesignal.NOTE8—Inapplicationsinwhichformingorflaringoperationsaretobeappliedtotheplatedcomponent,aductilenickelelectrodepositshouldbespecified.6.5.2Strikes—Itisrecommendedtoapplyagoldstriketotheunderplateorsubstrate,exceptifthelatterissilverorplatinum,priortoapplyingthegoldtopcoating.6.5.3Plating—Goodpracticecallsforpartstobeelectri-callyconnectedwhenenteringthegoldplatingsolution.Aminimumof0.5Vissuggested.NOTE9—Forrackandbarrelplatingprocessing,residualplatingsaltscanberemovedfromthearticlesbyaclean,hot(50to100°C)waterrinse.Aminimumrinsetimeof2.5min(rack)or5min(barrel)issuggested.Bestpracticecallsforaminimumofthreedragoutrinsesandonerunningrinsewithdwelltimesof40sineachstationwhenrackplatingand80swhenbarrelplating.Modern,high-velocityimpingement-typerinsescanreducethistimetoafewseconds.Thisisparticularlyusefulinautomaticreel-to-reelapplicationsinwhichdwelltimesaresignificantlyreduced.7.CoatingRequirementsCoatingRequirements7.1NatureofCoating—Thegolddepositshallmeettheappropriatepurityrequirementsasputforthinthefollowing:7.1.1TypeIcoatingsshallcontainatleast99.70mass%gold,excludingpotassium,sodium,carbonandnitrogen.ForTypeICodeA(“soft”)coatingsonly,metallichardeningagentssuchasnickel,cobaltorironcombined,shallbelessthan0.05mass%andnoneofthesethreeelementsshallbepresentinanTABLE1CoatingThicknessClassMinimumThickness,µm0.250.250.500.500.750.751.01.01.251.252.52.55.05.0B488–01(2006)3CopyrightbyASTMInt'l(allrightsreserved);ReproductionauthorizedperLicenseAgreementwithMoniqueTyree(ASTMIHSAccount);MonApr2413:21:14EDT2006CopyrightASTMInternationalProvidedbyIHSunderlicensewithASTMLicensee=DefenseSupplyCtr/5913977001NotforResale,01/10/200820:55:28MSTNoreproductionornetworkingpermittedwithoutlicensefromIHS--`,,`````,`,,`,``,,,,,````-`-`,,`,,`,`,,`---amountgreaterthan0.03mass%.Allothermetalsexcludingpotassiumandsodiumareconsideredimpuritiesandshallnotbepresentinamountsgreaterthan0.05mass%combined.ForTypeICodeBndCcoatings,metallichardeningagentssuchasnickel,cobaltorironcombinedshallbeequaltoorlessthan0.3mass%.Allothermetalsareconsideredimpuritiesandshallnotbepresentinamountsgreaterthan0.05%mass%each,0.1%combined.Thegoldpurityshallbecalculatedbydeterminingthecontentofallnon-goldmetalsinmass%(exceptpotassiumandsodium)andsubtractingthisvaluefrom100%.7.1.2TypeIIcoatingsshallcontainatleast99.00mass%gold,excludingpotassium,sodium,carbonandnotrogen.TypeIIcoatingsmaycontainmetallichardeningagents,suchasnickel,cobaltoriron,whichmaybepresentinamountsgreaterthan0.3mass%.Allothermetals,excludingpotassiumandnitrogen,shallbeconsideredimpuritiesandshallnotbepresentinamountsgreaterthan0.1mass%each.Thegoldpurityshallbecalculatedbydeterminingthecontentofallnon-goldmetalsinmass%(exceptpotassiumandsodium)andsubtractingthisvaluefrom100%.7.1.3TypeIIIcoatingsshallcontainatleast99.90mass%gold,excludingpotassium,sodium,carbonandnitrogen.Individualmetalimpuritiesshallnotbepresentinaquantitygreaterthan0.04mass%.Iron,nickelandcobaltcombinedshallbelessthan0.05mass%,andnoneofthesethreeelementsshallbepresentinanamountgreaterthan0.03mass%.Allnon-goldmetals,excludingpotassiumandsodium,areconsideredimpuritiesandshallnotbepresentinamountsgreaterthan0.1mass%combined.Thegoldpurityshallbecalculatedbydeterminingthecontentofallnon-goldmetalsinmass%(exceptpotassiumandsodium)andsubtractingthisvaluefrom100%.7.2Hardness—ThegoldcoatingshallhaveaKnoophard-nesswithinthespecifiedrangeasshownin4.2.3whentestedinaccordancewith9.2.7.3Appearance—Goldcoatingsshallbecoherent,continu-ous,andhaveauniformappearancetotheextentthatthenatureofthebasismetalandgoodcommercialpracticespermit.7.4Thickness:7.4.1Thegoldcoatingshallhaveathicknessonthesignificantsurfacesinaccordancewith4.3unlessotherwisespecified.NOTE10—WhereTypeI(CodeBorC)orTypeII(CodeBorC)goldisspecified,improvedprotectionoftheunderlyingmetalscanbeobtainedbyapplyingaduplexgoldcompositecoatingconsistingofanunderlyinglayerofTypeIII(CodeA)gold.TypicalthicknessesoftheTypeIIIgoldunderlayerare10to30%ofthetotalspecifiedthickness.However,caremustbetakentoensurethatthethicknessoftheTypeIorTypeIIgoldtopcoatissufficientsoasnottocompromisewearproperties.Whenmeasuringthetotalgoldthicknessofduplexcompositecoatings,adensityof17.5g/cm3shouldbeemployed(see9.4).7.4.2Thethicknessofthegoldcoatingshallbeequaltoorexceedthespecifiedthicknessthroughoutthesignificantsur-face(see3.2.1).Whenplatedpartsareusedinmatingapplications,themaximumthicknessshallnotexceedthetolerancespecifiedforthepartonitsengineeringdrawing.Itiscustomarythatallowanceforplatedcoatingsbeincludedwithintheparttolerance.NOTE11—Thecoatingthicknessrequirementofthisspecificationisaminimumrequirement:thatis,thecoatingthicknessisrequiredtoequalorexceedthespecifiedthicknessthroughoutthesignificantsurfaces,whileconformingtoallmaximumallowedthicknessescreatedbypartdimen-sionaltolerancesgivenintheengineeringdrawing.Variationinthecoatingthicknessfrompointtopointonacoatedarticleisaninherentcharacteristicofelectroplatingprocesses.Therefore,thecoatingthicknessatanysinglepointonthesignificantsurfacewillsometimeshavetoexceedthespecifiedvalueinordertoensurethatthethicknessequalsorexceedsthespecifiedvalueatallpoints.Hence,mostaveragecoatingthicknesseswillbegreaterthanthespecifiedvalue;howmuchgreaterislargelydeterminedbytheshapeofthearticle(seePracticeB507)andthecharacteristicsoftheplatingprocess.Inaddition,theaveragecoatingthicknessonarticleswillvaryfromarticletoarticlewithinaproductionlot.Therefore,ifallthearticlesinaproductionlotaretomeetthethicknessrequirement,theaveragecoatingthicknessfortheproductionlotasawholewillbegreaterthantheaveragenecessarytoensurethatanysinglearticlemeetstherequirement(see8.1).7.5Adhesion—Thegoldcoatingsshallbeadherenttothesubstratewhentestedbyoneoftheproceduressummarizedin9.5.7.6IntegrityoftheCoating:7.6.1GrossDefects/MechanicalDamage—Thecoatingsshallbefreeofvisiblemechanicaldamageandsimilargrossdefectswhenviewedatmagnificationsupto103.Forsomeapplicationsthisrequirementmayberelaxedtoallowforasmallnumberofsuchdefects(perunitarea),especiallyiftheyareoutsideorontheperipheryofthesignificantsurfaces(see7.6.2).7.6.2Porosity—Almostallas-platedelectrodepositscontainsomeporosity.Thetolerableamountofporosityinthecoatingdependsontheseverityoftheenvironmentthatthearticleislikelytoencounterduringserviceorstorage.Iftheporesarefewinnumberorawayfromthesignificantsurfaces,theirpresencecanoftenbetolerated.Suchacceptance(orpass-fail)criteria,ifrequired,shallbepartoftheproductspecificationfortheparticulararticleorcoatingrequiringtheporositytest(see9.6forporositytesting).8.Sampling8.1Theproducerisurgedtoemploystatisticalprocesscontrolinthecoatingprocess.Properlyperformed,thisprocesswillensurecoatedproductsofsatisfactoryqualityandwillreducetheamountofacceptanceinspection.Thesamplingplanusedfortheinspectionofthequalityofthecoatedarticlesshallbeasagreeduponbetweenthepurchaserandthesupplier.NOTE12—Usually,withacollectionofcoatedarticles,theinspectionlot(see8.2)isexaminedforcompliancewiththerequirementsplacedonthearticles,arelativelysmallnumberofthearticles,thesample,isselectedatrandomandisinspected.Theinspectionlotisthenclassifi