SMT锡膏详解Part 1

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1、GeneralInformationonSolderPaste-16-GeneralInformationonSolderPaste1.KindofsolderpasteTherearevariousdifferenttypesofsolderpasteavailabletoday.Thoseproductsshallgenerallybecategorizedinthefollowingmannerbytypeofflux.WatersolubleHalidecontainingtypeHalidefreetypeCleaningtypeNo-cleantyp

2、eFig.1Watersolublesolderpasteistobecleanedbypuredeionizedwater.SinceKokino-cleansolderpastes,boththehalidecontainingandhalidefreesolderpastesareallrosinbased,solvent,suchasHCFC,andsaponifiershallberecommendedasacleaner.Mostofourhalidefreesolderpastes,however,arequitedifficulttocleann

3、omatterhowitiscleaned,andmayleavewhiteresidue.Maincomponentwhichtendstoremainonthesubstrateaftercleaningisnormallythixotropicmaterials.Becauseeasy-to-cleanthixotropicmaterialstendtobedifficulttoeffectivelycontrolslumpresistivityofsolderpaste,notmuchattentionispaidforthecleanabilitywh

4、enselectingthixotropicmaterialsasmoreimportanceisattachedtoslumpresistancefeature.Kokiisspecializedinno-cleansolderpastes,HalidecontainingsolderpasteandHalidefreesolderpaste.IncreaseofpackagedensityalongwithcompletebanofCFCsgreatlyurgedtheindustryfortheimplementationofno-cleanprocess

5、.Asrequirementsfortheprocessonthebothworkabilityandreliabilityarebecomingmorestrictandprecise,no-cleansolderpastehasbeendiversifiedaccordingly.Itisoftenregardedthatno-cleansolderpastemustbehalidefree.Itmustbeclearlyunderstoodthatevenhalidecontainingsolderpastecanbeusedforno-cleanproc

6、essaswellbecausetocleanornotmustbedeterminedinaccordancewithreliabilityrequirementsoffinishedproducts.Infact,theuseofhalidecontaining(0.2%)solderpasteforno-cleanproductionismuchmorepopularinJapanthanthatofhalidefreepaste.Ingeneralcomparison,halidecontainingpastehasbetterworkability,s

7、uchassolderability,butoftenexhibitsinferiorreliabilitytohalidefreetype,suchasinsulationresistance.Thiscanbeattributedmainlytoitshigheractivationstrength.Relationbetweensolderabilityandreliabilitycouldbeexpressedbytheseesaw.-16-SolderabilityReliabilityTherefore,sofarasno-cleansolderin

8、gprocessisco