Kev daws teeb meem thiab kev kho ntawm PCBs tuaj yeem txuas ntxiv lub neej ntawm circuits.Yog tias muaj qhov yuam kev PCB tau ntsib thaum lub sijhawm sib dhos PCB, lub rooj tsavxwm PCB tuaj yeem kho tau raws li qhov xwm txheej ntawm qhov tsis ua haujlwm.Hauv qab no yog qee txoj hauv kev rau kev daws teeb meem thiab kho PCBs.
1. Yuav ua li cas tswj tau zoo ntawm PCB thaum lub sijhawm tsim khoom?
Feem ntau, PCB cov chaw tsim khoom muaj cov cuab yeej tshwj xeeb thiab cov txheej txheem tseem ceeb uas ua kom muaj kev tswj xyuas zoo ntawm PCBs thoob plaws hauv kev tsim khoom.
1.1.AOI Inspection
Kev tshuaj xyuas AOI tuaj yeem kuaj xyuas cov khoom ploj, cov khoom tsis raug, thiab lwm yam tsis xws luag ntawm PCB.AOI cov cuab yeej siv lub koob yees duab los ntes ntau cov duab ntawm PCB thiab muab piv nrog cov ntaub ntawv siv.Thaum kuaj pom qhov tsis sib haum, nws tuaj yeem qhia qhov ua yuam kev.
1.2.Flying Probe Test
Kev sojntsuam ya davhlau yog siv los txheeb xyuas cov luv luv thiab qhib circuits, cov khoom tsis raug (diodes thiab transistors), thiab qhov tsis xws ntawm kev tiv thaiv diode.Ntau txoj hauv kev kho PCB tuaj yeem siv los kho cov luv luv thiab cov khoom tsis raug.
1.3.Kev xeem FCT
FCT (Functional Test) feem ntau tsom rau kev sim ua haujlwm ntawm PCBs.Cov kev ntsuas ntsuas feem ntau yog muab los ntawm engineers thiab tej zaum yuav suav nrog kev sim hloov yooj yim.Qee zaum, tshwj xeeb software thiab cov txheej txheem meej yuav tsum tau.Kev ntsuas kev ua haujlwm ncaj qha tshuaj xyuas qhov ua haujlwm ntawm PCB raws li lub ntiaj teb ib puag ncig tiag tiag.
2. Tej yam ua rau PCB puas
Kev nkag siab txog qhov ua rau PCB tsis ua haujlwm tuaj yeem pab koj txheeb xyuas qhov tsis raug PCB sai.Nov yog qee qhov yuam kev:
Cov khoom ua tsis tiav: Hloov cov khoom puas tuaj yeem ua rau lub voj voog ua haujlwm zoo.
Kub kub: Yog tias tsis muaj kev tswj xyuas kom zoo, qee cov khoom yuav raug hlawv.
Lub cev puas tsuaj: Qhov no feem ntau yog tshwm sim los ntawm kev tuav rawv,
ua rau cov kab nrib pleb hauv cov khoom, cov pob qij txha, cov ntaub npog ntsej muag, cov kab, thiab cov ntaub qhwv.
Kev kis kab mob: Yog tias PCB raug mob hnyav, cov kab mob thiab lwm yam khoom siv tooj liab yuav raug corroded.
3. Yuav daws teeb meem PCB Faults li cas?
Cov npe hauv qab no yog 8 txoj hauv kev:
3-1.Nkag siab txog Circuit Court schematic
Muaj ntau yam khoom ntawm PCB, sib cuam tshuam los ntawm cov kab tooj liab.Nws suav nrog cov khoom siv hluav taws xob, hauv av, thiab ntau yam teeb liab.Tsis tas li ntawd, muaj ntau yam circuits, xws li lim, decoupling capacitors, thiab inductors.Kev nkag siab txog cov no yog qhov tseem ceeb rau kev kho PCB.
Paub yuav ua li cas taug qab txoj hauv kev tam sim no thiab cais cov ntu tsis raug yog nyob ntawm kev nkag siab txog lub voj voog schematic.Yog hais tias lub schematic tsis muaj, nws yuav tsum tau rov qab engineer lub schematic raws li PCB layout.
3-2.Kev tshuaj xyuas qhov muag
Raws li tau hais ua ntej, overheating yog ib qho tseem ceeb ntawm PCB faults.Txhua yam khoom siv hluav taws kub, cov kab, lossis cov pob qij txha tuaj yeem pom tau yooj yim pom thaum tsis muaj hluav taws xob nkag.Qee qhov piv txwv ntawm qhov tsis xws luag muaj xws li:
- Bulging / sib tshooj / cov khoom ploj lawm
- Cov kab tsis muaj xim
- Cold solder pob qij txha
- Ntau dhau solder
- Tombstoned Cheebtsam
- Ncua tseg / ploj lawm pads
- Kev tawg ntawm PCB
Tag nrho cov no tuaj yeem pom los ntawm kev tshuaj xyuas qhov muag.
3-3.Sib piv nrog Identical PCB
Yog tias koj muaj lwm tus PCB zoo ib yam nrog ib qho kev ua haujlwm zoo thiab lwm qhov tsis raug, nws yuav yooj yim dua.Koj tuaj yeem pom qhov sib piv cov khoom, qhov tsis zoo, thiab qhov tsis xws hauv cov kab lossis vias.Tsis tas li ntawd, koj tuaj yeem siv multimeter los kuaj xyuas cov tswv yim thiab cov ntawv nyeem ntawm ob lub rooj tsavxwm.Cov txiaj ntsig zoo sib xws yuav tsum tau txais vim tias ob lub PCBs zoo ib yam.
3-4.Isolate Faulty Components
Thaum kev soj ntsuam pom tsis txaus, koj tuaj yeem tso siab rau cov cuab yeej xws li multimeter lossis LCR meter.Ntsuam xyuas txhua yam ntawm tus kheej raws li cov ntaub ntawv thiab cov qauv tsim.Piv txwv xws li resistors, capacitors, inductors, diodes, transistors, thiab LEDs.
Piv txwv li, koj tuaj yeem siv qhov teeb tsa diode ntawm lub multimeter los kuaj diodes thiab transistors.Base-collector thiab base-emitter junctions ua raws li diodes.Rau kev tsim qauv Circuit Court yooj yim, koj tuaj yeem tshawb xyuas qhov qhib thiab luv luv hauv txhua qhov kev sib txuas.Tsuas yog teeb tsa lub 'meter' mus rau qhov kev tawm tsam lossis kev txuas mus ntxiv thiab txuas ntxiv mus sim txhua qhov kev sib txuas.
Thaum ua cov tshev, yog tias cov ntawv nyeem nyob hauv cov lus qhia tshwj xeeb, cov khoom siv tau suav tias ua haujlwm zoo.Yog tias qhov kev nyeem ntawv txawv txav los yog siab tshaj qhov xav tau, tej zaum yuav muaj teeb meem nrog cov khoom siv lossis cov pob qij txha.Kev nkag siab txog qhov xav tau voltage ntawm cov ntsiab lus xeem tuaj yeem pab hauv kev txheeb xyuas Circuit Court.
Lwm txoj hauv kev los ntsuas cov khoom yog los ntawm kev tshuaj xyuas nodal.Txoj kev no suav nrog kev siv hluav taws xob rau cov khoom xaiv thaum tsis siv hluav taws xob tag nrho thiab ntsuas qhov hluav taws xob teb (V- teb).Txheeb xyuas tag nrho cov nodes thiab xaiv cov ntaub ntawv siv txuas nrog cov khoom tseem ceeb lossis cov khoom siv hluav taws xob.Siv Kirchhoff Txoj Cai Lij Choj Tam Sim No (KCL) los xam qhov tsis paub ntawm qhov tsis paub qhov voltages (variables) thiab xyuas seb cov nuj nqis no phim cov kev xav tau.Yog tias muaj teeb meem pom ntawm ib qho ntawm qhov tshwj xeeb, nws qhia tau tias muaj kev ua txhaum ntawm qhov node.
3-5.Test Integrated Circuits
Kev ntsuas kev sib xyaw ua ke tuaj yeem ua haujlwm tseem ceeb vim lawv qhov nyuaj.Nov yog qee qhov kev xeem uas tuaj yeem ua tau:
- Txheeb xyuas tag nrho cov cim thiab ntsuas IC siv lub ntsuas ntsuas ntsuas lossis oscilloscope.
- Txheeb xyuas seb IC yog taw qhia kom raug.
- Xyuas kom meej tias txhua qhov sib txuas txuas nrog IC yog nyob rau hauv kev ua haujlwm zoo.
- Txheeb xyuas qhov xwm txheej ntawm cov dab dej kub los yog cov thermal pads txuas nrog IC kom ntseeg tau tias muaj cua sov kom zoo.
3-6.Kev kuaj fais fab
Yuav kom daws tau qhov teeb meem ntawm cov khoom siv hluav taws xob, nws yog ib qho tsim nyog los ntsuas qhov hluav taws xob hluav taws xob.Cov kev nyeem ntawv ntawm lub voltmeter tuaj yeem cuam tshuam cov tswv yim thiab cov txiaj ntsig ntawm cov khoom.Kev hloov pauv hauv qhov hluav taws xob tuaj yeem qhia tau tias muaj teeb meem hauv Circuit Court.Piv txwv li, kev nyeem ntawv ntawm 0V ntawm lub tsheb ciav hlau yuav qhia tau tias muaj luv luv Circuit Court nyob rau hauv lub hwj chim mov, ua rau cov khoom overheating.Los ntawm kev ua qhov kev ntsuam xyuas lub zog ruaj khov thiab sib piv cov txiaj ntsig xav tau rau qhov ntsuas qhov tseeb, cov khoom siv hluav taws xob muaj teeb meem tuaj yeem raug cais tawm.
3-7.Txheeb xyuas Circuit Hotspots
Thaum pom tsis pom qhov tsis xws luag, kev tshuaj xyuas lub cev los ntawm kev txhaj tshuaj fais fab tuaj yeem siv los ntsuas lub voj voog.Kev sib txuas tsis raug tuaj yeem tsim kom muaj cua sov, uas tuaj yeem hnov los ntawm kev tso tes ntawm lub rooj tsav xwm hauv Circuit Court.Lwm qhov kev xaiv yog siv lub koob yees duab thermal, uas feem ntau nyiam rau cov hluav taws xob qis.Yuav tsum tau ceev faj txog kev nyab xeeb kom tsis txhob muaj hluav taws xob.
Ib txoj hauv kev yog los xyuas kom meej tias koj tsuas siv ib txhais tes rau kev sim.Yog tias pom qhov kub thiab txias, nws yuav tsum tau txias, thiab tom qab ntawd tag nrho cov ntsiab lus txuas yuav tsum tau kuaj xyuas seb qhov teeb meem nyob qhov twg.
3-8.Kev daws teeb meem nrog Kev Tshawb Fawb Kev Tshawb Fawb
Txhawm rau siv cov txheej txheem no, nws yog ib qho tseem ceeb kom muaj kev nkag siab txog qhov xav tau qhov tseem ceeb thiab waveforms ntawm cov ntsiab lus xeem.Kev ntsuas hluav taws xob tuaj yeem ua tau ntawm ntau lub ntsiab lus siv multimeter, oscilloscope, lossis ib qho khoom siv waveform capture.Kev txheeb xyuas cov txiaj ntsig tuaj yeem pab cais cov yuam kev.
4. Cov cuab yeej xav tau rau kev kho PCB
Ua ntej kev kho, nws yog ib qho tseem ceeb uas yuav tau sau cov cuab yeej tsim nyog rau txoj haujlwm, raws li cov lus hais tias, 'Ib rab riam yuav tsis txiav ntoo.'
● Ib lub rooj ua haujlwm uas muaj ESD grounding, lub qhov hluav taws xob, thiab teeb pom kev zoo yog qhov tseem ceeb.
● Txhawm rau txwv cov thermal shocks, infrared heaters los yog preheaters yuav tsum tau preheat lub Circuit Court board.
● Ib qho kev ua kom zoo drilling yog xav tau rau kev sib tw thiab lub qhov qhib thaum lub sijhawm kho.Qhov system no tso cai rau kev tswj cov kab uas hla thiab qhov tob ntawm lub qhov.
● Ib tug zoo soldering hlau yog tsim nyog rau soldering los xyuas kom meej solder pob qij txha.
● Tsis tas li ntawd, kuj yuav tsum tau electroplating.
● Yog hais tias lub npog ntsej muag lub ntsej muag puas lawm, nws yuav tsum tau kho.Hauv qhov no, epoxy resin txheej yog qhov zoo dua.
5. Kev ceev faj txog kev nyab xeeb thaum kho PCB
Nws yog ib qho tseem ceeb rau kev tiv thaiv kev tiv thaiv kom tsis txhob muaj kev nyab xeeb thaum lub sij hawm kho.
● Cov Khoom Siv Tiv Thaiv: Thaum ua haujlwm nrog qhov kub thiab txias lossis lub zog siab, hnav cov cuab yeej tiv thaiv yog qhov yuav tsum tau ua.Kev nyab xeeb tsom iav thiab hnab looj tes yuav tsum hnav thaum lub sij hawm soldering thiab drilling txheej txheem, los tiv thaiv tej yam tshuaj lom.
Hnav hnab looj tes thaum kho PCBs.
● Electrostatic Discharge (ESD): Txhawm rau tiv thaiv hluav taws xob los ntawm ESD, nco ntsoov tshem tawm cov hluav taws xob thiab tso tawm cov hluav taws xob seem.Koj tuaj yeem hnav wristbands hauv av lossis siv cov mats los tiv thaiv zoo li qub kom txo qis kev pheej hmoo ntawm ESD.
6. Yuav Kho PCB li cas?
Feem ntau ua txhaum hauv PCB feem ntau cuam tshuam nrog cov kab mob, cov khoom siv, thiab cov ntaub so ntswg.
6-1.Kho tej yam uas puas lawm
Txhawm rau kho cov kab tawg lossis puas rau ntawm PCB, siv cov khoom ntse los nthuav tawm thaj tsam ntawm cov kab qub qub thiab tshem tawm daim npog ntsej muag.Ntxuav cov tooj liab nto nrog cov kuab tshuaj kom tshem tawm cov khib nyiab, pab kom ua tiav cov hluav taws xob txuas ntxiv zoo dua.
Xwb, koj tuaj yeem siv cov hlua khi hlua khi los kho cov kab.Xyuas kom meej tias cov hlau txoj kab uas hla sib phim cov kab dav rau kev ua tau zoo.
6-2.Hloov Faulty Cheebtsam
Hloov cov khoom puas
Txhawm rau tshem tawm cov khoom tsis raug lossis cov khoom siv ntau dhau los ntawm cov pob qij txha, nws yog ib qho tsim nyog yuav tsum tau yaj lub solder, tab sis yuav tsum tau ceev faj kom tsis txhob muaj kev ntxhov siab ntawm qhov chaw nyob ib puag ncig.Ua raws li cov kauj ruam hauv qab no los hloov cov khoom hauv Circuit Court:
● Ua kom sov cov pob qij txha sai sai siv cov hlau los yog cov cuab yeej desoldering.
● Thaum lub solder melted, siv lub twj tso kua mis desoldering kom tshem tawm cov kua.
● Tom qab tshem tag nrho cov kev sib txuas, cov khoom yuav raug muab tshem tawm.
● Tom ntej no, sib sau ua ke cov khoom tshiab thiab solder nws nyob rau hauv qhov chaw.
● Txiav qhov ntev ntev ntawm cov khoom siv coj los siv cov hlau txiav.
● Xyuas kom meej tias cov terminals txuas nrog raws li qhov xav tau polarity.
6-3.Repairing Damaged Solder Pads
Nrog lub sijhawm txav mus los, cov ntaub qhwv ntsej muag ntawm PCB tuaj yeem nqa, corrode, lossis tawg.Ntawm no yog cov txheej txheem rau kev kho cov puas solder pads:
Lifted Solder Pads: Ntxuav thaj chaw nrog cov kuab tshuaj siv cov paj rwb swab.Txhawm rau khi lub ncoo rov qab rau hauv qhov chaw, siv cov khoom siv hluav taws xob epoxy ntawm cov ntaub qhwv thiab nias nws, cia cov epoxy resin kho ua ntej txuas ntxiv nrog cov txheej txheem soldering.
Pua puas los yog kab mob Solder Pads: Tshem tawm los yog txiav tawm cov ntaub qhwv uas puas lawm, nthuav tawm cov kab sib txuas los ntawm kev tshem tawm lub npog ntsej muag nyob ib ncig ntawm lub ncoo.Ntxuav thaj chaw nrog cov kuab tshuaj siv cov paj rwb swab.Nyob rau hauv lub tshiab solder ncoo (txuas mus rau ib tug kab), thov ib txheej ntawm conductive epoxy resin thiab ruaj ntseg nyob rau hauv qhov chaw.Tom ntej no, ntxiv epoxy resin nruab nrab ntawm cov kab thiab cov ntaub qhwv.Kho nws ua ntej pib nrog cov txheej txheem soldering.
Shenzhen ANKE PCB Co., Ltd
2023-7-20
Post lub sij hawm: Lub Xya hli ntuj-21-2023
