Nyob rau hauv tus txheej txheem ntawm PCB tsim thiab tsim, engineers tsis tsuas yog yuav tsum tau tiv thaiv kev raug mob thaum lub sij hawm tsim PCB, tab sis kuj yuav tsum tau zam tsis tsim tsim yuam kev. Kab lus no tau sau thiab txheeb xyuas cov teeb meem PCB no, vam tias yuav coj qee yam kev pab rau txhua tus tsim thiab tsim ua haujlwm.
Teeb meem 1: PCB board luv Circuit Court
Qhov teeb meem no yog ib qho kev ua txhaum uas yuav ua rau lub rooj tsav xwm PCB tsis ua hauj lwm, thiab muaj ntau qhov laj thawj rau qhov teeb meem no. Cia peb tsom xam ib los ntawm ib qho hauv qab no.
Qhov laj thawj loj tshaj plaws ntawm PCB luv Circuit Court yog qhov tsim tsis zoo ntawm cov ntaub qhwv. Nyob rau lub sijhawm no, lub voj voog puag ncig tuaj yeem hloov pauv mus rau ib qho oval zoo kom nce qhov kev ncua deb ntawm cov ntsiab lus los tiv thaiv luv luv Circuit Court.
Kev tsim tsis tsim nyog ntawm kev taw qhia ntawm PCB qhov chaw tseem yuav ua rau lub rooj tsavxwm luv luv thiab ua haujlwm tsis tau. Piv txwv li, yog tias tus pin ntawm SOIC yog sib npaug rau tin yoj, nws yooj yim ua rau muaj kev sib tsoo luv luv. Lub sijhawm no, qhov kev taw qhia ntawm ib feem tuaj yeem hloov kho kom tsim nyog ua kom nws nyob rau sab xis ntawm tin yoj.
Muaj lwm txoj hauv kev uas yuav ua rau luv luv Circuit Court tsis ua haujlwm ntawm PCB, uas yog, tsis siv neeg plug-in bent ko taw. Raws li IPC tau teev tseg tias qhov ntev ntawm tus pin yog tsawg dua 2 hli thiab muaj kev txhawj xeeb tias cov khoom yuav poob thaum lub kaum sab xis ntawm cov ceg khoov loj dhau, nws yooj yim ua rau luv luv, thiab cov khoom sib txuas yuav tsum muaj ntau dua. 2 mm deb ntawm Circuit Court.
Ntxiv rau peb qhov laj thawj uas tau hais los saum toj no, kuj tseem muaj qee qhov laj thawj uas tuaj yeem ua rau luv luv ntawm PCB lub rooj tsavxwm, xws li cov substrate loj dhau, qhov kub ntawm lub qhov cub kub tsis zoo, tsis zoo solderability ntawm lub rooj tsavxwm, tsis ua haujlwm ntawm daim npog ntsej muag. , thiab board Surface pollution, thiab lwm yam, yog ib qho ua rau ua tsis tiav. Cov kws tshaj lij tuaj yeem sib piv cov laj thawj saum toj no nrog qhov tshwm sim ntawm qhov tsis ua haujlwm tshem tawm thiab xyuas ib qho los ntawm ib qho.
Teeb meem 2: Tsaus thiab grainy hu tshwm rau ntawm lub rooj tsavxwm PCB
Qhov teeb meem ntawm cov xim tsaus lossis cov pob qij txha me me ntawm PCB feem ntau yog vim muaj cov kab mob sib kis thiab cov oxides ntau dhau los sib xyaw hauv cov molten tin, uas ua rau cov qauv sib koom ua ke yog nkig heev. Ceev faj kom tsis txhob thab nws nrog cov xim tsaus uas tshwm sim los ntawm kev siv solder nrog cov ntsiab lus tin tsawg.
Lwm qhov laj thawj rau qhov teeb meem no yog qhov muaj pes tsawg leeg ntawm cov khoom siv hauv kev tsim khoom tau hloov pauv, thiab cov ntsiab lus impurity siab dhau lawm. Nws yog ib qho tsim nyog yuav tau ntxiv cov tin ntshiab los yog hloov lub solder. Cov iav stained ua rau lub cev hloov pauv hauv cov fiber ntau tsim, xws li kev sib cais ntawm cov khaubncaws sab nraud povtseg. Tab sis qhov teeb meem no tsis yog vim tsis zoo solder pob qij txha. Yog vim li cas yog vim li cas lub substrate yog rhuab heev, yog li nws yog tsim nyog los txo lub preheating thiab soldering kub los yog ua rau kom ceev ntawm substrate.
Teeb meem peb: PCB solder pob qij txha ua golden daj
Raws li ib txwm muaj, lub solder ntawm PCB board yog nyiaj grey, tab sis qee zaus cov pob qij txha golden tshwm. Qhov laj thawj tseem ceeb ntawm qhov teeb meem no yog qhov kub thiab txias heev. Nyob rau lub sijhawm no, koj tsuas yog yuav tsum tau txo qhov kub ntawm lub cub tawg.
Nqe Lus Nug 4: Lub rooj tsav xwm phem kuj raug cuam tshuam los ntawm ib puag ncig
Vim yog cov qauv ntawm PCB nws tus kheej, nws yooj yim ua rau kev puas tsuaj rau PCB thaum nws nyob hauv ib puag ncig tsis zoo. Qhov kub thiab txias los yog qhov kub thiab txias, cov av noo ntau dhau, kev vibration siab thiab lwm yam kev mob yog txhua yam uas ua rau kev ua haujlwm ntawm lub rooj tsavxwm raug txo los sis txawm tias raug tshem tawm. Piv txwv li, kev hloov ntawm qhov kub thiab txias yuav ua rau deformation ntawm lub rooj tsavxwm. Yog li ntawd, cov pob qij txha yuav raug rhuav tshem, lub rooj tsavxwm zoo yuav khoov, lossis cov kab tooj liab ntawm lub rooj tsavxwm yuav tawg.
Ntawm qhov tod tes, cov dej noo hauv huab cua tuaj yeem ua rau oxidation, corrosion thiab xeb ntawm cov hlau, xws li cov khoom siv tooj liab, cov pob qij txha, cov ntaub qhwv thiab cov khoom siv. Kev sib sau ntawm cov av, plua plav, lossis cov khib nyiab ntawm qhov chaw ntawm cov khoom siv thiab cov khoom siv hluav taws xob tuaj yeem txo cov cua ntws thiab cua txias ntawm cov khoom, ua rau PCB overheating thiab kev ua haujlwm tsis zoo. Kev vibration, poob qis, ntaus lossis khoov lub PCB yuav deform nws thiab ua rau cov tawg tshwm sim, thaum lub siab tam sim no los yog overvoltage yuav ua rau PCB tawg los yog ua rau kev laus sai ntawm cov khoom thiab txoj hauv kev.
Teeb meem tsib: PCB qhib Circuit Court
Thaum cov kab tawg, los yog thaum lub solder tsuas yog nyob rau ntawm lub ncoo thiab tsis nyob rau hauv cov khoom ua, ib qho qhib Circuit Court tuaj yeem tshwm sim. Hauv qhov no, tsis muaj adhesion lossis kev sib txuas ntawm cov khoom siv thiab PCB. Ib yam li luv luv Circuit Court, cov no kuj tuaj yeem tshwm sim thaum tsim khoom lossis vuam thiab lwm yam haujlwm. Kev vibration los yog ncab ntawm lub rooj tsavxwm Circuit Court, xa me nyuam rov los yog lwm yam khoom siv kho tshuab deformation yuav rhuav tshem cov kab los yog cov pob qij txha. Ib yam li ntawd, tshuaj lom neeg lossis cov dej noo tuaj yeem ua rau cov khoom siv hlau los yog hlau hnav, uas tuaj yeem ua rau cov khoom tawg.
Teeb meem rau: xoob lossis misplaced Cheebtsam
Thaum lub sij hawm reflow txheej txheem, me me tej zaum yuav ntab ntawm lub molten solder thiab nws thiaj li tawm ntawm lub hom phiaj solder sib koom. Cov laj thawj muaj peev xwm rau qhov kev hloov pauv lossis qaij suav nrog kev vibration lossis thaws ntawm cov khoom ntawm cov khoom siv hluav taws xob PCB vim tsis muaj kev txhawb nqa Circuit Court board, reflow qhov cub, teeb meem solder paste, thiab tib neeg yuam kev.
Teeb meem xya: welding teeb meem
Cov hauv qab no yog qee qhov teeb meem tshwm sim los ntawm kev siv vuam tsis zoo:
Disturbed solder joints: Lub solder txav ua ntej solidification vim yog sab nraud cuam tshuam. Qhov no zoo ib yam li cov pob qij txha txias, tab sis vim li cas thiaj txawv. Nws tuaj yeem raug kho los ntawm kev rov ua kom sov thiab xyuas kom meej tias cov pob qij txha tsis raug cuam tshuam los ntawm sab nraud thaum lawv txias.
Cold welding: Qhov xwm txheej no tshwm sim thaum lub solder tsis tuaj yeem yaj kom zoo, ua rau cov tawv nqaij tsis zoo thiab tsis muaj kev sib txuas. Txij li cov solder ntau dhau tiv thaiv kom tiav melting, txias solder pob qij txha kuj tuaj yeem tshwm sim. Txoj kev kho yog kom rov ua kom qhov sib koom ua ke thiab tshem tawm cov solder ntau dhau.
Solder choj: Qhov no tshwm sim thaum solder crosses thiab lub cev txuas ob qho tib si ua ke. Cov no tuaj yeem tsim kev sib txuas tsis tau xav txog thiab luv luv Circuit Court, uas yuav ua rau cov khoom siv hluav taws xob kub hnyiab los yog kub hnyiab tawm cov kab thaum tam sim no siab dhau.
Pad: ntub dej tsis txaus ntawm cov hlau lead lossis txhuas. Ntau dhau los yog me ntsis solder. Pads uas tau nce vim overheating los yog ntxhib soldering.
Teeb meem yim: tib neeg yuam kev
Feem ntau ntawm qhov tsis xws luag hauv PCB raug tsim los ntawm tib neeg kev ua yuam kev. Feem ntau, cov txheej txheem tsim khoom tsis raug, kev tso kawm tsis raug ntawm cov khoom thiab cov kev tsim khoom tsis raug cai tuaj yeem ua rau 64% ntawm cov khoom tsis raug. Vim yog cov laj thawj hauv qab no, qhov muaj peev xwm ua rau muaj qhov tsis xws luag nce nrog kev sib tw hauv Circuit Court thiab cov txheej txheem ntau lawm: cov khoom ntim ntom ntom ntom ntom; ntau txheej txheej Circuit Court; kab hlau rhuav; nto soldering Cheebtsam; lub zog thiab cov dav hlau hauv av.
Txawm hais tias txhua lub chaw tsim khoom lossis cov neeg tsim khoom cia siab tias PCB pawg thawj coj ua tsis muaj qhov tsis xws luag, tab sis muaj ntau yam teeb meem tsim thiab txheej txheem tsim khoom uas ua rau muaj teeb meem PCB txuas ntxiv.
Cov teeb meem thiab cov txiaj ntsig muaj xws li cov ntsiab lus hauv qab no: cov khoom siv tsis zoo tuaj yeem ua rau luv luv Circuit Court, qhib circuits, txias solder pob qij txha, thiab lwm yam; misalignment ntawm lub rooj tsavxwm txheej tuaj yeem ua rau kev sib cuag tsis zoo thiab kev ua haujlwm tsis zoo; kev rwb thaiv tsev tsis zoo ntawm cov kab tooj liab tuaj yeem ua rau cov kab mob thiab cov kab mob muaj qhov arc ntawm cov xov hlau; yog tias cov kab tooj liab tau muab tso rau nruj heev ntawm cov vias, muaj kev pheej hmoo ntawm luv luv Circuit Court; tsis txaus thickness ntawm lub rooj tsavxwm Circuit Court yuav ua rau khoov thiab puas.