印刷電路板表面處理 - OSP 工藝簡介

深圳市福英達工業(yè)技術(shù)有限公司/一站式錫膏解決方案供應商PCBsurfacetreatment-Introduction

totheOSPprocess

PCBsurfacetreatmentistocoverthePCBsurfacewithaprotectivelayertopreventcopperoxidation,corrosionandtoimprovesolderability,reliabilityandaesthetics.therearevariousPCBsurfacetreatmentprocesses,suchastinspraying,goldsinking,silversinking,etc.,ofwhichOSPisanenvironmentallyfriendlyprocessthatmeetstherequirementsoftheRoHSdirective.

WhatisOSP?OSPistheabbreviationforOrganicSolderabilityPreservatives,alsoknownasbarecopper,Entek.simplyput,OSPisanorganicskinfilmthatgrowschemicallyonacleanbarecoppersurface.Thisfilmisresistanttooxidation,thermalshockandhumidityandprotectsthecoppersurfacefromfurtherrusting(oxidationorsulphidationetc.)inthenormalenvironment;however,inthesubsequenthighsolderingtemperatures,thefilmmustbeeasilyandquicklyremovedbythefluxsothattheexposedcleancoppersurfacecanbeimmediatelybondedtothemoltensolderinaveryshorttime.TherearethreemaintypesofOSPmaterials:rosin,activeresinsandazoles.CurrentlythemostwidelyusedistheazoleOSP.

OSPprocessflow1.Pre-treatment:ThePCBiscleaned,degreasedandmicro-etchedtoremovedirt,greaseandoxidesfromthesurface,increasethesurfaceroughnessandimprovetheadhesionoftheOSPfilm.2.Filmformation:ThePCBisdippedintoasolutioncontainingazolecompoundsandotheradditivestoallowtheazolecompoundstoreactonthecoppersurfacetoformatransparent,denseanduniformorganicsolderfilm.3.Post-treatment:ThePCBiswashedanddriedtoremoveresidualsolutionsandimpuritiesandtoincreasetheglossandflatnessofthesolderretentionfilm.WhataretheadvantagesanddisadvantagesoftheOSPprocess?

ThefollowingrequirementsneedtobeobservedduringtheuseofOSPplates:1.theeffectiveservicelifeoftheOSPboardshouldbecompletedwithin48H/72H(accordingtoPCBfactoryspecifications).2.OSPboardsmustnotbebaked,asbakingwillcausetheOSPfilmtocrackandloseitsprotectivecapacity.3.OSPboardsmustnotbecleaned,solventcleaningandwater-basedcleaningagentswilldissolvetheOSPfilmandleadtolossofprotection.4.OSPboardsshouldbeusedinanenvironmentthatfollowstherequirementsoftheindustry:controlthetemperatureandhumidityvalues,PCBAworkshoptemperatureandhumiditycontrolrangeisgenerally28+3℃(or18~28℃),40%RH~60%RH(somecompaniescontrolat40%RH~70%RH).5.TheOSPboardshouldbecleanedwithasmallhand-heldscrapertoremovethesolderpaste,thenwipewithwipingpaperordust-freepaper(donotdipintosolvent)ortapebondingtocleanup,andfinallyusethepressureairguntocleanup,andputintouseaftermicroscopicinspectiontoconfirmOK.6.Long-termstorageofOSPboardorexpiredOSPuseneedtobereturnedtothePCBfactorytoremovethefilm,pickling,Recoatingandthenputintouse.However,attentionshouldbepaidtothecontrolofthepicklingofthecopperfoilofthesolderpads,asthethinningofthecopperfoilcausedbyexcessivepicklinghasanimpactonthereliabilityoftheproduct.Inshort,OSPboardsurfacetreatmentislowcost,superiorperformance,