Kuv tau nug cov lus nug no tsawg kawg nees nkaum zaug. Ib ntus dhau los, ib tug tub hluas uas nyuam qhuav pib tawm tuaj rau kuv nrog ob lub raj ntawm ib yam dab tsi thiab nug tias, "Xib Hwb, ob qho tib si tsis yog paste? Qhov txawv li cas?" Kuv tsuas yog luag- ob yam no yuav zoo sib xws, tab sis yog tias koj sib xyaw ua ke, koj yuav ua teeb meem ntawm cov kab ntau lawm tsis muaj sijhawm.
Yog li, qhov xaus yog:solder muab tshuaj txhuam thiab fluxyog cov khoom sib txawv kiag li, tab sis lawv muaj feem xyuam nrog -flux yog ib feem ntawm cov tshuaj txhuam hniav, ua li 10% mus rau 15%.
Ua ntej, cia peb nkag siab tias ob yam khoom no yog dab tsi?
Solder paste, tseem hu ua solder paste, yog greyish - cov khoom siv xim av, zoo li cov tshuaj txhuam hniav tab sis tuab dua, yog tias koj tau ua haujlwm ntawm SMT ntau lawm kab. Vim li cas grey? Vim tias nws muaj cov hmoov hlau loj, feem ntau yog cov hlau nplaum, nyiaj, thiab tooj liab, uas ua rau ntau dua 85% ntawm nws cov khoom xyaw. Qhov seem yog flux thiab qee cov additives.
Solder muab tshuaj txhuam
Solder paste txoj hauj lwm yog ncaj nraim: mus rau cov khoom siv hluav taws xob rau hauv PCB pawg thawj coj saib, tsim cov khoom siv hluav taws xob thiab cov khoom siv sib txuas. Cias muab, nws yog cov khoom uas yeej tuav cov khoom ua ke thiab muab hluav taws xob conductivity.
Flux
Flux, hauv lus Askiv, hu ua Flux, uas txhais tau tias 'lub flux uas pab nrog soldering'. Nws tsis solder nws tus kheej, tab sis yog tsis muaj nws, qhov zoo soldering yuav txo tau ho. Nws cov khoom tseem ceeb yog rosin, activators, thiab cov kuab tshuaj, thiab nws tuaj yeem ua kua, muab tshuaj, lossis khoom.
Kuv piav qhia txog kev ua haujlwm ntawm flux hauv plaub lo lus: kev tshem tawm xeb thiab tiv thaiv.
Hlau nto raug rau huab cua oxidize, tsim cov oxide zaj duab xis. Solder tsis ntub cov zaj duab xis no thiab tsis tuaj yeem soldered. Lub activator nyob rau hauv lub flux reacts nrog oxide thiab tshem tawm nws. Nyob rau tib lub sijhawm, qhov kub thiab txias thaum lub sij hawm soldering ua rau cov flux los ua ib qho kev tiv thaiv zaj duab xis rau ntawm qhov chaw solder, tiv thaiv cov molten solder tshiab los ntawm kev oxidized dua.
Lawv siv li cas hauv kev xyaum?
Ob yam no muaj kev siv sib txawv kiag li. To taub qhov no yuav tiv thaiv tsis meej pem.
Txhua tus neeg uas ua SMT (Nto Mount Technology) paub tias reflow soldering siv solder paste. Ua ntej, solder paste yog luam tawm rau ntawm PCB pads siv stencil. Tom qab ntawd, tus xaiv-thiab- qhov chaw tshuab tso cov resistors, capacitors, ICs, thiab lwm yam khoom rau lawv. Thaum kawg, cov khoom dhau los ntawm lub qhov cub reflow, qhov twg cov tshuaj txhuam hniav melts thiab solidifies, sib sau ua ke sib koom ua ke. Lub solder muab tshuaj txhuam tuav tag nrho cov hauj lwm soldering; cov flux tivthaiv tshem tawm oxidation thiab pab nrog ntub dej.
Txawm li cas los xij, qhov xwm txheej txawv rau yoj soldering, phau ntawv soldering, lossis BGA rework. Nyob rau hauv cov ntaub ntawv no, lub solder yog solder tuav los yog solder hlau, thiab flux yuav tsum tau ntxiv cais. Piv txwv li, ua ntej yoj soldering, ib txheej ntawm flux yuav tsum tau txau rau hauv qab ntawm PCB; nyob rau hauv phau ntawv soldering, txawm hais tias lub solder hlau core muaj ib co rosin, nws yuav tsum tau dipped nyob rau hauv ntxiv flux thaum ntsib hnyav oxidized pads.
Kuv tau pom cov neeg siv flux li solder paste, thov ib txheej rau cov ntaub qhwv thiab tom qab ntawd txuas ncaj qha rau cov khoom siv rov qab. Qhov tshwm sim yog kwv yees tau - cov khoom tag nrho poob tawm, vim tias tsis muaj hlau solder hauv cov flux; nws tsis solder dab tsi.
Flux Classification: Tsuas yog siv dab tsi tsim nyog
IPC kev faib tawm yog qhov nyuaj heev, nrog cov ntsiab lus xws li RO, RE, LOSSIS, IN, ua raws li L, M, H los qhia txog qib kev ua haujlwm, thiab 0 thiab 1 los qhia seb nws puas muaj halogens. Frankly, rau kev ua haujlwm txhua hnub, koj tsis tas yuav cim tag nrho cov ntsiab lus ntawd; paub ob peb lub ntsiab lus tseem ceeb txaus.
Kev faib tawm los ntawm kev tu kom huv yog qhov ua tau zoo tshaj plaws: Tsis muaj- cov dej huv huv tawm me ntsis seem thiab feem ntau siv ncaj qha rau hauv cov khoom siv hluav taws xob; dej- cov dej huv huv tawm ntau qhov seem tab sis tuaj yeem ntxuav nrog dej, tsim nyog rau cov khoom lag luam muaj kev ntseeg siab; cov kuab tshuaj- cov dej huv huv yuav tsum muaj cov tshuaj ntxuav tshwj xeeb thiab feem ntau pom muaj nyob hauv tub rog, aerospace, thiab chaw kho mob.
Qib kev ua si kuj tseem ceeb. Kev ua haujlwm siab dua txhais tau tias muaj peev xwm deoxidizing muaj zog dua, tab sis kuj muaj ntau dua corrosiveness ntawm residue. Peb lub Hoobkas yav dhau los tau txais ib pawg ntawm cov khoom siv rov ua haujlwm vim tias siab - cov dej ntws tsis zoo tsis raug ntxuav, thiab teeb meem corrosion tshwm sim tom qab rau lub hlis. Yog li ntawd, muaj zog ntau dua tsis yog ib txwm zoo dua; nws nyob ntawm daim ntawv thov tshwj xeeb.
Lub flux ua li cas thaum lub sij hawm reflow soldering?
Qhov no yog me ntsis ntxiv technical, tab sis nkag siab nws pab nrog parameter tuning.
Lub qhov cub reflow feem ntau muaj plaub qhov chaw kub. Hauv thaj chaw cua sov, qhov kub thiab txias maj mam nce los ntawm chav tsev kub mus txog 150 degrees Celsius. Lub sijhawm no, cov flux pib qhib, thiab cov kuab tshuaj pib evaporate. Nyob rau hauv lub preheating cheeb tsam, qhov kub tseem nce mus txog ib ncig ntawm 180 degrees Celsius, qhov twg cov flux yog nquag nquag, reacting nrog cov oxides ntawm cov ntaub qhwv thiab cov khoom ua. Tom qab ntawd, nyob rau hauv cheeb tsam soldering, qhov kub nce mus txog qhov siab tshaj plaws (feem ntau yog 240-}250 degrees Celsius rau cov hlau tsis muaj hlau lead), cov hlau melts, thiab cov flux tsim ib zaj duab xis tiv thaiv kom tsis txhob molten solder los ntawm oxidizing. Thaum kawg, nyob rau hauv qhov chaw txias, qhov kub thiab txias poob, thiab solder sib koom ua ke solidifies.
Vim li cas lub sij hawm preheating txaus tseem ceeb? Nws yog tso cai rau cov flux kom ua tiav nws txoj haujlwm. Tsis txaus preheating txhais tau hais tias cov kuab tshuaj tsis tau evaporated kiag li, ua rau crackling solder npas thaum nkag mus rau qhov siab -kub cheeb tsam; ntau dhau preheating depletes cov flux ntxov ntxov, tawm hauv thaj tsam soldering tsis muaj kev tiv thaiv, thiab cov pob qij txha zoo li greyish thiab npub.
Muaj ntau yam pitfalls:
Ua ntej, flux tsis zoo ib yam li solder paste. Flux yog pob tshab los yog daj ntseg daj, tsis muaj hlau, thiab tsuas yog pab nyob rau hauv soldering. Solder paste yog greyish -dub, muaj cov hmoov hlau nkaus xwb, thiab yog cov khoom siv tiag tiag. Cov xim yog yooj yim distinguishable.
Qhov thib ob, tsis muaj - ntxuav tsis tau txhais hais tias koj tsis tas yuav ntxuav nws. Rau cov neeg siv khoom siv hluav taws xob dav dav, cov khoom seem los ntawm tsis muaj - cov dej huv huv tsis cuam tshuam rau kev siv tau. Txawm li cas los xij, rau siab - cov khoom lag luam muaj kev ntseeg siab, txawm tias tsis muaj - cov dej huv huv, tseem tsim nyog tu. Hauv peb cov OEM tsim khoom siv kho mob, tus neeg siv khoom IQC nruj heev; txawm tias tsis muaj -cov boards huv si tau txais kev kuaj kab mob ion.
Thib peb, leaded thiab lead-dawb flux yuav tsum tau siv ua ke. Lead-dawb solder paste yuav tsum tau siv nrog cov hmoov lead -dawb flux, thiab leaded flux nrog leaded flux. Thaum sib tov lawv tsis tiv thaiv soldering, qhov ua kom kub ntawm cov flux thiab lub melting point ntawm solder yuav tsis sib xws, uas ua rau soldering tsis zoo.
Thaum kawg, ob peb lo lus:
Kev nkag siab qhov sib txawv ntawm solder paste thiab flux tsis yog qhov nyuaj. Cia li nco ntsoov qhov no: solder paste yog lub ntsiab tivthaiv, twb muaj flux; flux plays lub luag haujlwm txhawb nqa, siv nrog rau lwm cov ntaub ntawv ntawm solder. Tsis txhob cuam tshuam lawv hauv koj txoj haujlwm. Xaiv cov ntaub ntawv raws li cov txheej txheem yuav tsum tau ua, thiab feem ntau koj yuav zam teeb meem.
Yog tias koj tseem muaj lus nug, kuv xav kom ncaj qha mus rau cov kab ntau lawm kom pom koj tus kheej. Kov thiab hnov tsw lawv; nws muaj txiaj ntsig ntau dua li nyeem cov ntawv nyeem ntau npaum li cas.
