使用氮气来保护回流焊接

深圳市福英达工业技术有限公司/一站式锡膏解决方案供应商ReflowSolderingwithNitrogenProtectionIntheprocessoflead-freereflowsoldering,manycompaniesareconcernedaboutonequestion,thatis,whethertheoxygenconcentrationinthereflowovenwillrise?WhatcircumstancesneedtouseN2toprotectthesolderingmethodtoreducetheoxygenconcentrationinthereflowoven?Infact,forconsumerelectronicsproducts,takingintoaccountthefactorsofproductdesignandservicelife,itisbesttoavoidtheuseofN2shieldedreflowsolderingmethodsthatincreaseproductioncosts.However,ifthereliabilityoftheproductisveryhigh,thentheuseofN2shieldedsolderingshouldbeconsidered.Duetothehighmeltingpointoflead-freesolder,itiseasytocauseoxidationproblemsduringthesolderingprocess,whichaffectsthequalityandreliabilityofsoldering.Inordertosolvethisproblem,aneffectivemethodistofillthereflowovenwithN2toformalow-oxygenenvironment,blockingtheentryofairandreducingtheoccurrenceofoxidationreactions.Figure1.ReflowovenappearanceTheprincipleofreflowsolderingN2protectionistousetheinertnessofN2,andmetalorothersubstancesdonothaveachemicalreaction,soastoinhibittheoxidationofthesolderingprocess.WhenthereflowfurnaceisfilledwithN2withapurityhigherthan99.99%(oxygenconcentrationbelow100ppm),theoxygenconcentrationinthefurnacecanbeeffectivelyreduced,generallycontrolledwithin2000~3000ppm.Inthisway,itcanreducethepossibilityoflead-freesolderreactingwithoxygenintheairathightemperaturestoformmetaloxides,improvethewettingperformanceandwettingspeedofthesolder,avoidthegenerationofdefectssuchastinballsandbridging,andgetbettersolderingquality.Figure2.IndustrialliquidnitrogenAdvantagesofreflowN2protectionPreventorreducetheoxidationofcomponents,circuitboardsandsolderathightemperaturetoprolongtheirservicelife;Improvethewettingpowerandwettingspeedofthesolder,makingthesolderjointssmoother,moreuniformandtighter;Reducingthegenerationofdefectssuchassolderballsandbridging,andimprovingtheappearanceandperformanceofproducts;Thepossibilityofusingsolderpasteswithloweractivefluxes,reducingresiduesandcorrosiveness;Reductionofdiscolourationanddeformationofthesubstrate,improvingtheaestheticsoftheproduct.DisadvantagesofreflowN2protectionSignificantincreaseinproductioncosts;Mayincreasetheriskoftombstoneeffectandwickeffect,needtopayattentiontocontrollingparameterssuchascomponentspacing,temperatureprofileandpreheatingtime;NeedtocontroltheoxygencontentandN2consumptioninthefurnacetoavoidwasteandpollution.ReflowsolderingN2protectionisapplicabletothefollowingsituationsWhenusinghigh-temperaturelead-freesoldersuchasSnAgCu,itiseasytocauseseriousoxidationofcomponents,circuitboardsandsolderathightemperaturesduetotheincreasedmeltingpoint;WhenusingOSPsurfacetreatmentdouble-sidedreflowsolderingboards,duetotheOSPlayeristhinandeasytodamage,intheaireasytolo