Lub hom phiaj tseem ceeb ntawm PCB ci yog kom dehumidify thiab tshem tawm cov dej noo, thiab tshem tawm cov dej noo hauv PCB los yog absorbed los ntawm sab nraud, vim qee cov ntaub ntawv siv hauv PCB nws tus kheej yooj yim tsim cov dej molecules.

Tsis tas li ntawd, tom qab lub PCB raug tsim thiab muab tso rau ib lub sijhawm, muaj lub sijhawm los nqus dej noo hauv ib puag ncig, thiab dej yog ib qho tseem ceeb ntawm cov neeg tua neeg ntawm PCB paj kws lossis delamination.

Vim hais tias thaum lub PCB muab tso rau hauv ib qho chaw uas qhov kub thiab txias tshaj 100 ° C, xws li reflow qhov cub, yoj soldering qhov cub, cua kub leveling los yog tes soldering, cov dej yuav tig mus rau hauv dej vapor thiab sai sai nthuav nws ntim.

Thaum cov cua kub ceev ntawm PCB sai dua, cov dej vapor yuav nthuav dav dua; thaum qhov kub siab dua, qhov ntim ntawm cov dej vapor yuav loj dua; Thaum cov dej vapor tsis tuaj yeem khiav tawm ntawm PCB tam sim ntawd, muaj lub sijhawm zoo los nthuav dav PCB.

Tshwj xeeb, Z kev taw qhia ntawm PCB yog qhov yooj yim tshaj plaws. Qee lub sij hawm lub vias ntawm cov khaubncaws sab nraud povtseg ntawm PCB tuaj yeem tawg, thiab qee zaum nws yuav ua rau kev sib cais ntawm cov khaubncaws sab nraud povtseg ntawm PCB. Txawm tias hnyav dua, txawm tias cov tsos ntawm PCB tuaj yeem pom. Phenomenon xws li blistering, o, thiab tawg;

Qee lub sij hawm txawm tias cov xwm txheej saum toj no tsis pom nyob rau sab nraud ntawm PCB, nws tau raug mob sab hauv. Sij hawm dhau mus, nws yuav ua rau tsis muaj zog ntawm cov khoom siv hluav taws xob, lossis CAF thiab lwm yam teeb meem, thiab thaum kawg ua rau cov khoom tsis ua haujlwm.

Kev tshuaj xyuas qhov tseeb ntawm PCB tawg thiab kev tiv thaiv kev ntsuas
Cov txheej txheem ci PCB yog qhov teeb meem tiag tiag. Thaum lub sij hawm ci, thawj lub ntim yuav tsum tau muab tshem tawm ua ntej nws tuaj yeem muab tso rau hauv qhov cub, thiab tom qab ntawd qhov kub yuav tsum tshaj 100 ℃ rau ci, tab sis qhov kub yuav tsum tsis txhob siab dhau kom tsis txhob muaj lub sijhawm ci. Kev nthuav dav ntawm dej vapor ntau dhau yuav tawg rau PCB.

Feem ntau, PCB ci kub hauv kev lag luam feem ntau yog teem rau ntawm 120 ± 5 ° C los xyuas kom meej tias cov dej noo tuaj yeem raug tshem tawm los ntawm PCB lub cev ua ntej nws tuaj yeem raug soldered ntawm SMT kab mus rau reflow rauv.

Lub sij hawm ci txawv nrog lub thickness thiab loj ntawm PCB. Rau thinner lossis loj dua PCBs, koj yuav tsum nias lub rooj tsavxwm nrog cov khoom hnyav tom qab ci. Qhov no yog txhawm rau txo lossis zam PCB Qhov tshwm sim txaus ntshai ntawm PCB dabtsi yog khoov deformation vim muaj kev ntxhov siab tso tawm thaum lub caij txias tom qab ci.

Vim hais tias ib zaug PCB deformed thiab khoov, yuav muaj offset los yog tsis sib xws thickness thaum luam ntawv solder paste nyob rau hauv SMT, uas yuav ua rau ib tug loj tus naj npawb ntawm solder luv circuits los yog khoob soldering tsis xws luag thaum lub sij hawm tom qab reflow.

Tam sim no, kev lag luam feem ntau teev cov xwm txheej thiab sijhawm rau PCB ci raws li hauv qab no:

1. Lub PCB raug kaw zoo hauv 2 lub hlis ntawm hnub tsim khoom. Tom qab unpacking, nws yog muab tso rau hauv ib tug kub thiab av noo tswj ib puag ncig (≦30 ℃ / 60% RH, raws li IPC-1601) rau ntau tshaj 5 hnub ua ntej mus online. Ci ntawm 120 ± 5 ℃ rau 1 teev.

2. Lub PCB khaws cia rau 2-6 lub hlis dhau los ntawm hnub tsim khoom, thiab nws yuav tsum tau ci ntawm 120 ± 5 ℃ rau 2 teev ua ntej yuav mus online.

3. Lub PCB khaws cia rau 6-12 lub hlis dhau ntawm hnub tsim khoom, thiab nws yuav tsum tau ci ntawm 120 ± 5 ° C rau 4 teev ua ntej yuav mus online.

4. PCB yog khaws cia rau ntau tshaj 12 lub hlis txij li hnub tsim khoom. Yeej, nws tsis pom zoo kom siv nws, vim hais tias cov nplaum nplaum ntawm lub rooj tsavxwm multilayer yuav muaj hnub nyoog dhau lub sijhawm, thiab cov teeb meem zoo xws li cov khoom tsis ruaj khov yuav tshwm sim yav tom ntej, uas yuav ua rau kev lag luam kho dua tshiab. Tsis tas li ntawd, cov txheej txheem tsim khoom kuj tseem muaj kev pheej hmoo xws li phaj tawg thiab tsis zoo tin noj. Yog tias koj yuav tsum siv nws, nws raug nquahu kom ci nws ntawm 120 ± 5 ° C rau 6 teev. Ua ntej pawg ntau lawm, ua ntej sim luam ob peb daim ntawm cov tshuaj txhuam thiab xyuas kom meej tias tsis muaj teeb meem solderability ua ntej yuav txuas ntxiv.

Lwm qhov laj thawj yog tias nws tsis pom zoo kom siv PCBs uas tau khaws cia ntev dhau lawm vim tias lawv qhov kev kho saum npoo yuav maj mam ua tsis tau raws sijhawm. Rau ENIG, lub txee lub neej ntawm kev lag luam yog 12 lub hlis. Tom qab lub sijhawm txwv no, nws nyob ntawm qhov tso nyiaj kub. Lub thickness nyob ntawm qhov tuab. Yog hais tias lub thickness yog thinner, cov nickel txheej yuav tshwm sim ntawm cov kub txheej vim diffusion thiab daim ntawv oxidation, uas cuam tshuam rau kev ntseeg tau.

5. Tag nrho cov PCBs uas tau muab ci yuav tsum tau siv tsis pub dhau 5 hnub, thiab cov PCBs uas tsis tau ua tiav yuav tsum tau ci ntawm 120 ± 5 ° C rau lwm 1 teev ua ntej yuav mus online.