Koj yuav tsum xyuam xim rau dab tsi thaum siv cov hlau tsis muaj hlau lead?
Hauv SMT thaj ua haujlwm, thev naus laus zis tsis muaj hlau lead yog qhov yuav tsum tau ua hauv ib puag ncig kev sib raug zoo, thiab cov khoom siv hluav taws xob tsis muaj hlau lead yog nrhiav kev tiv thaiv ib puag ncig ntsuab. Txhawm rau ua tiav cov txheej txheem tsis muaj txhuas mus txog qhov kawg, kev xaiv cov hlau soldering yog qhov tshwj xeeb. Lub melting point ntawm lead-free solder hlau yog 34 degree siab tshaj qhov uas feem ntau siv sn63pb37. Nws yog ib qho nyuaj rau ua SMT soldering nrog ib tug dav soldering hlau. Txawm hais tias lub zog nce, nws nyuaj rau solder. Lub ntsiab yog vim li cas yog hais tias ib zaug ib tug general soldering hlau hu rau PCB ncoo, qhov kub thiab txias tam sim ntawd poob. Thaum lub sij hawm, cov flux carbonizes thiab tsis tuaj yeem wetted.
Cov ntsiab lus tseem ceeb ntawm cov txheej txheem tsis muaj txhuas: Feem ntau, qhov tsim nyog soldering kub yog lub melting point + 40 degree, thiab qhov chaw kub ntawm cov hlau soldering yog qhov melting point + 150 degree .
Dab tsi yog txoj hauv kev los xaiv cov hlau soldering nrog cov txheej txheem tsis muaj txhuas?
Rau cov hlau tsis muaj hlau lead, koj yuav tsum siv qhov kub ceev-replenishing soldering hlau, xws li kub-tswj soldering hlau tsim los nrog kev siv hluav taws xob hloov tshuab. Thaum tsis vuam, nws tuaj yeem tswj tau ntawm lub zog qis, thiab nws yuav rov qab sai sai thaum vuam thiab muaj lub zog tso zis siab (lub zog tso zis yuav tsum hloov pauv).
Tus yuam sij rau kev xaiv cov hlau tsis muaj hlau lead tsis yog qhov kub ntawm cov hlau uas tuaj yeem ncav cuag, tab sis seb nws puas tuaj yeem muab qhov kub thiab txias uas yuav tsum tau siv rau lub sijhawm luv luv (lub peev xwm los muab cov cua sov uas xav tau hauv lub sijhawm luv). Muaj ntau lub npe zoo dua ntawm cov hlau tsis muaj hlau lead, xws li OK, Qianzhu, ERSA, thiab Baiguang. Thaum siv cov hlau lead-dawb soldering hlau rau SMT nti ua, koj yuav tsum xyuam xim rau 5 cov ntsiab lus hauv qab no:
(1) Ua ntej siv, qhov kub ntawm cov hlau soldering yuav tsum tau teem rau 250 degree, thiab lub taub hau hlau yuav tsum tau kho ua ntej (tinned).
(2) Qhov zoo tshaj plaws SMT vuam kub yog 350 degree. Rau kev kub kub siab tshaj 400 degree, oxidation ceev ntawm cov hlau taub hau yog 2 mus rau 5 npaug ntawm 350 degree. Txhawm rau kom ua tiav SMT ua thiab vuam, ntau tus neeg ua haujlwm qee zaum teeb tsa qhov kub thiab txias rau 450 degree. Qhov no yog qhov tsis raug thiab yuav txo tau lub neej kev pab cuam ntawm cov hlau soldering, thiab txawm tias yuav tsum tau hloov lub taub hau hlau hauv peb hnub.
(3) Nws yog nruj me ntsis txwv tsis pub siv cov ntawv xuab zeb los txhuam cov hlau taub hau.
(4) Tsis txhob siv ntau lub zog rau cov pob qij txha
(5) Kev ua haujlwm tsawg flux yuav tsum tau siv
Cov seem ntawm cov hlau lead-free soldering hlau yog feem ntau yog tin oxide (tsis zoo li cov hlau lead-muaj cov hlau, uas feem ntau yog flux carbide). Nws tuaj yeem rov qab tau ntev npaum li cov carbide ntawm qhov chaw raug tshem tawm ua ntej thiab txheej txheej tin plating yog tsim dua. Hom tin oxide no tsis tuaj yeem raug tshem tawm nrog kev tu xws li daim txhuam cev. Alumina hmoov los yog tshwj xeeb flux yuav tsum tau siv los tshem tawm nws. Nws yog nruj me ntsis txwv tsis pub siv cov ntaub ntawv tshem tawm (hlau plating tsuas yog 500μm).
