Raws li qhov loj ntawm PCBA Cheebtsam tau txais me me thiab me, qhov ceev tau nce siab dua; Qhov siab ntawm cov khoom siv thiab cov khoom siv (lub suab / av clearance ntawm PCB thiab PCB) kuj tau txais me me thiab me, thiab kev cuam tshuam ntawm ib puag ncig ntawm PCBA kuj nce ntxiv, yog li peb muab cov kev xav tau siab dua rau kev ntseeg tau. ntawm cov khoom siv hluav taws xob PCBA.
PCBA Cheebtsam los ntawm loj mus rau me me, los ntawm qhov sib txawv mus rau qhov sib txawv ntawm qhov sib txawv
Environmental yam thiab lawv cov teebmeem
Cov xwm txheej ib puag ncig xws li av noo, plua plav, tshuaj tsuag ntsev, pwm, thiab lwm yam, ua rau muaj teeb meem ntau yam ntawm PCBA
Cov av noo nyob rau hauv ib puag ncig sab nraud ntawm cov khoom siv hluav taws xob PCB, yuav luag txhua qhov muaj kev pheej hmoo ntawm kev xeb, ntawm cov dej yog qhov nruab nrab tseem ceeb tshaj plaws rau corrosion, dej molecules me me txaus nkag mus rau qhov sib txawv mesh molecular ntawm qee cov ntaub ntawv polymer rau sab hauv lossis los ntawm txheej pinholes kom ncav cuag lub hauv paus hlau corrosion. Thaum huab cua nce mus txog qee qhov av noo, nws tuaj yeem ua rau PCB electrochemical tsiv teb tsaws, xau tam sim no thiab teeb liab distortion hauv high-frequency circuits.
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Vapor/humidity + ionic contaminants (ntsev, flux active agents) = conductive electrolyte + stress voltage = electrochemical migration
Thaum RH nyob rau hauv cov huab cua nce mus txog 80%, yuav muaj 5 mus rau 20 molecules tuab dej zaj duab xis, txhua yam ntawm cov molecules yuav dawb do txav, thaum muaj carbon, tej zaum yuav tsim electrochemical tshuaj tiv thaiv; Thaum RH nce mus txog 60%, txheej txheej txheej ntawm cov cuab yeej yuav tsim cov yeeb yaj kiab dej nrog lub thickness ntawm 2 mus rau 4 cov dej molecules, thiab cov tshuaj lom neeg yuav tshwm sim thaum cov pa phem yaj rau hauv nws. Thaum RH <20% nyob rau hauv cov huab cua, yuav luag txhua qhov tshwm sim corrosion nres;
Yog li ntawd, kev tiv thaiv noo noo yog ib qho tseem ceeb ntawm kev tiv thaiv cov khoom.
Rau cov khoom siv hluav taws xob, cov dej noo tuaj nyob rau hauv peb hom: nag, condensation, thiab dej vapor. Dej yog ib qho electrolyte uas tuaj yeem yaj ntau ntawm corrosive ions uas corrode hlau. Thaum qhov kub ntawm ib feem ntawm cov khoom siv qis dua qhov "dew point" (kub), yuav muaj condensation rau saum npoo: cov khoom siv los yog PCBA.
hmoov av
Muaj cov plua plav hauv huab cua, thiab cov plua plav adsorbs ion pollutants los nyob hauv cov khoom siv hluav taws xob thiab ua rau tsis ua haujlwm. Qhov no yog ib qho ntawm cov kev ua tsis tiav hauv hluav taws xob hauv kev ua haujlwm.
Cov plua plav tau muab faib ua ob hom: cov hmoov av ntxhib yog cov khoom tsis sib xws nrog txoj kab uas hla ntawm 2.5 mus rau 15 microns, uas feem ntau tsis ua rau muaj teeb meem xws li tsis ua haujlwm, arc, tab sis cuam tshuam rau kev sib cuag ntawm cov khoom sib txuas; Cov plua plav zoo yog cov khoom tsis sib xws nrog txoj kab uas hla tsawg dua 2.5 microns. Cov plua plav zoo muaj qee qhov adhesion ntawm PCBA (veneer) thiab tuaj yeem raug tshem tawm los ntawm cov txhuam hniav zoo li qub.
Kev phom sij ntawm plua plav: a. Vim muaj plua plav nyob rau saum npoo ntawm PCBA, electrochemical corrosion yog generated, thiab tus nqi tsis ua hauj lwm yog nce; b. Plua plav + damp kub + ntsev tsuag muaj kev puas tsuaj loj tshaj plaws rau PCBA, thiab cov khoom siv hluav taws xob ua tsis tiav yog qhov feem ntau nyob rau hauv ntug dej hiav txwv, suab puam (saline-alkali av), thiab cov tshuaj lom neeg kev lag luam thiab mining thaj chaw ze ntawm Huaihe River thaum lub caij mildew thiab los nag. .
Yog li ntawd, kev tiv thaiv plua plav yog ib qho tseem ceeb ntawm kev tiv thaiv cov khoom.
Ntsev tsuag
Kev tsim cov tshuaj tsuag ntsev: ntsev tsuag yog tshwm sim los ntawm tej yam ntuj tso xws li nthwv dej, tides thiab atmospheric ncig (monsoon) siab, tshav ntuj, thiab yuav poob rau hauv av nrog cua, thiab nws cov concentration txo nrog qhov deb ntawm ntug dej hiav txwv, feem ntau 1Km los ntawm ntug dej hiav txwv yog 1% ntawm ntug dej (tab sis lub typhoon yuav tawg ntxiv).
Kev puas tsuaj ntawm ntsev tsuag: a. kev puas tsuaj rau cov txheej txheem hlau; b. Accelerated electrochemical corrosion tus nqi ua rau hlau hlau tawg thiab tivthaiv tsis ua hauj lwm.
Qhov zoo sib xws corrosion: a. Muaj ntsev, urea, lactic acid thiab lwm yam tshuaj nyob rau hauv tes hws, uas muaj cov nyhuv corrosive ntawm cov khoom siv hluav taws xob xws li tshuaj ntsev, yog li cov hnab looj tes yuav tsum tau hnav thaum sib dhos lossis siv, thiab cov txheej yuav tsum tsis txhob kov ntawm tes liab qab; b. Muaj halogens thiab acids nyob rau hauv lub flux, uas yuav tsum tau ntxuav thiab nws residual concentration tswj.
Yog li ntawd, kev tiv thaiv ntsev tsuag yog ib qho tseem ceeb ntawm kev tiv thaiv cov khoom.
pwm
Mildew, lub npe hu ua filamentous fungi, txhais tau hais tias "moldy fungi," uas zoo li tsim mycelium luxuriant, tab sis tsis tsim cov txiv hmab txiv ntoo loj zoo li nceb. Nyob rau hauv qhov chaw ntub thiab sov, ntau yam khoom loj hlob qee qhov pom fluff, flocculent lossis kab laug sab colony, uas yog pwm.
PCB pwm tshwm sim
Kev puas tsuaj ntawm pwm: a. pwm phagocytosis thiab propagation ua rau cov rwb thaiv tsev ntawm cov ntaub ntawv organic poob, kev puas tsuaj thiab tsis ua haujlwm; b. Cov metabolites ntawm pwm yog cov organic acids, uas cuam tshuam rau lub rwb thaiv tsev thiab hluav taws xob tiv thaiv thiab tsim arc.
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Yog li ntawd, anti-pwm yog ib qho tseem ceeb ntawm kev tiv thaiv cov khoom.
Xav txog cov yam ntxwv saum toj no, kev ntseeg siab ntawm cov khoom yuav tsum tau lees paub zoo dua, thiab nws yuav tsum raug cais tawm ntawm qhov chaw sab nraud kom tsawg li tsawg tau, yog li cov txheej txheem txheej txheej tau qhia.
Tom qab txheej txheej txheej ntawm PCB, cov nyhuv tua nyob rau hauv lub teeb liab qab, cov txheej txheem tseem tuaj yeem ua kom zoo nkauj heev!
Peb txheej txheej txheej yog hais txog PCB nto coated nrog ib txheej nyias ntawm rwb thaiv tsev tiv thaiv txheej, nws yog tam sim no feem ntau siv tom qab vuam txheej txheej txheej, qee zaum hu ua txheej txheej, txheej txheej txheej txheej (Lus Askiv lub npe txheej, txheej txheej txheej. ). Nws cais cov khoom siv hluav taws xob rhiab heev los ntawm ib puag ncig hnyav, txhim kho kev nyab xeeb thiab kev ntseeg siab ntawm cov khoom siv hluav taws xob thiab txuas ntxiv lub neej kev pab cuam ntawm cov khoom. Tri-resistant coatings tiv thaiv circuits / cov khoom los ntawm ib puag ncig yam xws li ya raws, kab mob, corrosion, kev nyuaj siab, poob siab, mechanical vibration thiab thermal cycling, thaum tseem txhim kho cov neeg kho tshuab lub zog thiab rwb thaiv tsev ntawm cov khoom.
Tom qab txheej txheej txheej txheej txheej, PCB tsim cov yeeb yaj kiab tiv thaiv pob tshab ntawm qhov chaw, uas tuaj yeem tiv thaiv kev nkag mus ntawm cov hlaws dej thiab dej noo, tsis txhob xau thiab luv luv.
2. Cov ntsiab lus tseem ceeb ntawm txheej txheej txheej
Raws li cov kev cai ntawm IPC-A-610E (Electronic Assembly Testing Standard), nws yog feem ntau tshwm sim hauv cov nram qab no
Complex PCB pawg thawj coj saib
1. Cov cheeb tsam uas tsis tuaj yeem coated:
Cov cheeb tsam uas xav tau kev sib txuas hluav taws xob, xws li cov ntaub qhwv kub, cov ntiv tes kub, cov hlau los ntawm qhov, qhov ntsuas qhov; Roj teeb thiab roj teeb mounts; Txuas; fuse thiab vaj tse; Thaum tshav kub kub dissipation ntaus ntawv; Jumper hlau; Lenses ntawm cov khoom siv kho qhov muag; Potentiometer; Sensor; Tsis muaj kev sib khi kaw; Lwm qhov chaw uas txheej txheej tuaj yeem cuam tshuam kev ua haujlwm lossis kev ua haujlwm.
2. Cov cheeb tsam uas yuav tsum tau coated: tag nrho cov solder pob qij txha, pins, tivthaiv conductors.
3. Cov cheeb tsam uas tuaj yeem pleev xim lossis tsis tau
tuab
Thickness yog ntsuas ntawm lub tiaj tus, tsis muaj kev tiv thaiv, kho qhov chaw ntawm cov khoom siv hluav taws xob luam tawm, lossis ntawm cov phaj txuas uas ua tiav cov txheej txheem tsim khoom nrog cov khoom siv. Lub rooj tsav xwm txuas nrog tej zaum yuav yog cov khoom siv tib yam li cov ntawv luam tawm lossis lwm yam khoom tsis ntxeem tau, xws li hlau lossis iav. Kev ntsuas cov yeeb yaj kiab ntub dej kuj tuaj yeem siv los ua ib txoj hauv kev xaiv rau txheej thickness ntsuas, muab cov ntaub ntawv hloov dua siab tshiab ntawm qhuav thiab ntub zaj duab xis thickness.
Table 1: Thickness range standard for every type of coating material
Thickness test method:
1. Dry film thickness Measuring tool: ib micrometer (IPC-CC-830B); b Dry Film Thickness Gauge (Iron base)
Micrometer qhuav zaj duab xis ntsuas
2. Kev ntsuas cov yeeb yaj kiab ntub dej: Lub thickness ntawm cov zaj duab xis ntub dej tuaj yeem tau txais los ntawm cov ntaub ntawv ntub dej ntub dej, thiab tom qab ntawd xam los ntawm kev faib ua feem ntawm cov kua nplaum cov ntsiab lus.
Thickness ntawm zaj duab xis qhuav
Cov zaj duab xis ntub dej yog tau los ntawm cov yeeb yaj kiab ntub dej tuab, thiab tom qab ntawd cov yeeb yaj kiab qhuav yog xam
Ntug daws teeb meem
Lus Txhais: Nyob rau hauv ib txwm muaj xwm txheej, cov tshuaj tsuag valve tsuag tawm ntawm kab ntug yuav tsis ncaj heev, yuav muaj ib qho burr. Peb txhais qhov dav ntawm burr raws li kev daws teeb meem ntawm ntug. Raws li qhia hauv qab no, qhov loj ntawm d yog tus nqi ntawm ntug kev daws teeb meem.
Lus Cim: Cov ntug kev daws teeb meem yog qhov me dua qhov zoo dua, tab sis cov neeg siv khoom sib txawv tsis zoo ib yam, yog li qhov tshwj xeeb coated ntug daws teeb meem ntev npaum li nws ua tau raws li cov neeg siv khoom xav tau.
Ntug daws teeb meem sib piv
Uniformity, cov kua nplaum yuav tsum zoo li cov tuab tuab thiab du pob tshab zaj duab xis npog ntawm cov khoom, qhov tseem ceeb yog nyob rau hauv uniformity ntawm cov kua nplaum npog hauv cov khoom saum toj no, ces nws yuav tsum yog tib lub thickness, tsis muaj teeb meem txheej txheem: tawg, stratification, txiv kab ntxwv kab, muaj kuab paug, capillary phenomenon, npuas.
Axis tsis siv neeg AC series tsis siv neeg txheej tshuab txheej nyhuv, uniformity zoo ib yam
3. Txoj kev ua kom pom tseeb ntawm txheej txheej txheej txheej txheej thiab txheej txheej txheej txheej
Kauj Ruam 1 Npaj
Npaj cov khoom thiab kua nplaum thiab lwm yam khoom tsim nyog; Txiav txim siab qhov chaw ntawm kev tiv thaiv hauv zos; Txheeb xyuas cov txheej txheem tseem ceeb
Kauj Ruam 2 Ntxuav
Nws yuav tsum tau muab ntxuav tsis pub dhau lub sij hawm luv tshaj tom qab vuam kom tsis txhob vuam cov av tsis yooj yim los ntxuav; Txiav txim siab seb cov kuab paug tseem ceeb yog polar lossis tsis-polar thiaj li xaiv tus neeg saib xyuas kom tsim nyog; Yog tias siv cov tshuaj ntxuav dej cawv, cov teeb meem kev nyab xeeb yuav tsum tau them rau: yuav tsum muaj qhov cua zoo thiab ua kom txias thiab ziab cov txheej txheem tom qab ntxuav, kom tsis txhob muaj cov kuab tshuaj volatilization tshwm sim los ntawm kev tawg hauv qhov cub; Kev ntxuav dej, ntxuav cov kua dej nrog alkaline ntxuav kua (emulsion), thiab tom qab ntawd ntxuav cov kua ntxuav nrog dej ntshiab kom ua tau raws li tus qauv tu;
3. Kev tiv thaiv daim npog ntsej muag (yog tias xaiv cov khoom siv txheej tsis siv), uas yog, daim npog ntsej muag;
Yuav tsum xaiv cov zaj duab xis uas tsis yog nplaum yuav tsis hloov daim kab xev; Anti-static daim kab xev yuav tsum tau siv los tiv thaiv IC; Raws li qhov yuav tsum tau ua ntawm kev kos duab, qee cov khoom siv tiv thaiv;
4.Dehumidify
Tom qab ntxuav, cov ntaub thaiv npog PCBA (cov khoom siv) yuav tsum tau ua kom qhuav thiab dehumidified ua ntej txheej; Txiav txim siab qhov kub / lub sij hawm ua ntej ziab raws li qhov kub thiab txias tso cai los ntawm PCBA (cov khoom siv);
Table 2: PCBA (cov khoom siv) tuaj yeem tso cai los txiav txim siab qhov kub / lub sijhawm ntawm lub rooj ua ntej ziab
Kauj ruam 5 Thov
Cov txheej txheem txheej txheej yog nyob ntawm PCBA kev tiv thaiv cov cai, cov txheej txheem cov cuab yeej siv thiab cov peev txheej uas twb muaj lawm, uas feem ntau ua tiav raws li hauv qab no:
a. Txhuam los ntawm tes
Tes painting txoj kev
Txhuam txheej yog cov txheej txheem siv dav tshaj plaws, tsim nyog rau kev tsim khoom me me, PCBA qauv yog qhov nyuaj thiab ntom, yuav tsum tau tiv thaiv kev tiv thaiv ntawm cov khoom hnyav. Vim tias txhuam hniav tuaj yeem tswj cov txheej txheem ntawm qhov siab, qhov chaw uas tsis tso cai rau pleev xim yuav tsis muaj kuab lom; Txhuam noj ntawm cov khoom siv tsawg tshaj plaws, tsim nyog rau tus nqi siab dua ntawm ob txheej txheej txheej; Cov txheej txheem txhuam hniav muaj qhov xav tau siab rau tus neeg teb xov tooj, thiab cov duab kos thiab cov txheej txheem yuav tsum tau ua tib zoo zom ua ntej kev tsim kho, thiab cov npe ntawm PCBA cov khoom tuaj yeem raug txheeb xyuas, thiab cov cim qhov muag yuav tsum tau muab tso rau hauv qhov chaw uas tsis raug tso cai. ua coated. Tus neeg teb xov tooj tsis raug tso cai kov cov ntawv luam tawm los ntawm tes txhua lub sijhawm kom tsis txhob muaj kab mob;
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b. Dip los ntawm tes
Tes dip txheej txheej txheem
Cov txheej txheem dip txheej muab cov txheej txheem zoo tshaj plaws, tso cai rau cov txheej txheem sib xws, txuas ntxiv mus rau txhua qhov ntawm PCBA. Cov txheej txheem dip txheej tsis haum rau PCBA Cheebtsam nrog cov capacitors adjustable, trimmer cores, potentiometers, khob-zoo li tus cores thiab qee cov khoom siv tsis zoo.
Qhov tseem ceeb ntawm cov txheej txheem dip txheej:
Kho qhov tsim nyog viscosity; Tswj qhov ceev ntawm PCBA yog nqa los tiv thaiv npuas los ntawm kev sib sau. Feem ntau tsis ntau tshaj 1 meter ib thib ob nce ceev;
c. Txau
Txau yog txoj kev siv dav tshaj plaws thiab lees txais tau yooj yim, uas tau muab faib ua ob pawg hauv qab no:
① Kev siv tshuaj txau
Manual spraying system
Nws yog qhov tsim nyog rau qhov xwm txheej uas cov khoom ua haujlwm yog qhov nyuaj thiab nyuaj rau kev cia siab rau cov khoom siv hluav taws xob rau cov khoom loj, thiab nws kuj yog qhov tsim nyog rau qhov xwm txheej uas cov khoom kab muaj ntau ntau yam tab sis tus nqi me me, thiab nws tuaj yeem txau rau. ib txoj hauj lwm tshwj xeeb.
Kev siv tshuaj tsuag yuav tsum tau muab sau tseg: cov xim pos huab yuav ua rau muaj kuab paug rau qee yam khoom siv, xws li PCB plug-ins, IC sockets, qee qhov rhiab heev thiab qee qhov chaw hauv av, cov khoom no yuav tsum tau them sai sai rau kev ntseeg siab ntawm kev tiv thaiv kev tiv thaiv. Lwm lub ntsiab lus yog tias tus neeg teb xov tooj yuav tsum tsis txhob kov cov ntawv luam tawm los ntawm tes txhua lub sijhawm los tiv thaiv kev kis kab mob ntawm lub ntsaws ntsaws.
② Tsis siv neeg txau
Nws feem ntau yog hais txog tsis siv neeg txau nrog cov khoom siv txheej txheej xaiv. Haum rau ntau lawm, zoo sib xws, siab precision, me ntsis ib puag ncig muaj kuab paug. Nrog rau kev txhim kho kev lag luam, kev txhim kho cov nqi zog thiab cov kev cai nruj ntawm kev tiv thaiv ib puag ncig, cov cuab yeej siv tshuaj txau tsis siv neeg maj mam hloov lwm txoj hauv kev.