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1、化学镍金工艺探讨（Discussiononchemicalnickelgoldprocess）Electrolessnickelgoldcoatingcanbewelded,touch,conductive,wire,heatdissipationandsoon.ItisasingleprocessofPCBboard,butithasamulti-purposewetprocess.Therearenootherprocessestocontendwithatthemoment.Buttheprocessisno
2、tgood,hasbeendoneforalongtime,theproblemoftenoccurs,anddifficulttoheavyindustry,theproblemmustberesolvedfromthesource.Inthisregard,Iwillworkintheprocessofqualityproblemsencounteredbytheindustrypredecessorstodiscuss.Firstly,thereactionmechanismofelectrolessnick
3、elandgoldisdiscussed.ChemicalnickelNickelsalt:mainlynickelsulfate,nickelchloride,nickelacetateReducingagent:sodiumdihydrogenphosphate,NaH2PO2Reactionmechanism:Note:oncethehypophosphiteionssodiumdihydrogenphosphatehydrolysisandoxidationofphosphate,whiletherelea
4、seoftwoactivehydrogenatomadsorbedonthecoppersurfaceonthebottomofpalladium.Thenickelionswererapidlyreducedtonickelontheactivatedpalladiumsurface.Asmallnumberofhypophosphiteproducedphosphorusatomsanddepositedinthenickellayerunderthestimulationofhydrogen.Partofth
5、ehypophosphiteinthecatalyticenvironment,theywillalsooxidizeandgeneratehydrogen,fromthesurfaceofthenickelout.Two,chemicalgoldWhenthePCBboardisplatedwiththenickellayer,thenickelsurfaceisdissolvedbythebathliquidtodissolvethenickelion,andthetwoelectronsthrownoutar
6、eobtainedbythegoldcyanideion,andthegoldlayerisdepositedonthenickelsurface.Reactionmechanism:NitoNi2+2eAu(CN)2-+e=Au+2CN-Thedepositionofanickelatomsdissolvedcanobtaintwogoldatoms,andbecausethegoldlayerhasmanysparsetiles,sothesurfaceiscoveredwithalayerofgold,but
7、stillletthenickelsurfacedissolvedperforatedandcontinuetoplatedgoldlayer,butmoreandmoreslowly.Secondly,theprocessofchemicalnickelgoldcontrol.First,pretreatment.1.:theuseofnylonbrushgrindingbrushhighmesh(1000-1200mesh)lightbrushonthesurface(brushcurrent2+0.2A)to
8、removedirtandoxide.Intheinterviewaftertheboardwhenthebrushmustwearcleanglovestoavoidcontactwiththemoldinglinewithintheplatingarea,soasnottodofollow-upboardsurfaceisspotted.2.:fatgr
