Pamene kukula kwa zigawo za PCBA kukucheperachepera, kachulukidwe kameneka kakukwera kwambiri;Kutalika pakati pa zida ndi zida (chilolezo cha phula / pansi pakati pa PCB ndi PCB) chikucheperachepera, ndipo chikoka cha zinthu zachilengedwe pa PCBA chikuchulukiranso, kotero timayika patsogolo zofunikira za kudalirika. zamagetsi zamagetsi PCBA.
Zida za PCBA kuyambira zazikulu mpaka zazing'ono, kuchokera pang'onopang'ono kupita kuzinthu zosinthira
Zinthu zachilengedwe ndi zotsatira zake
Zinthu wamba zachilengedwe monga chinyezi, fumbi, mchere kutsitsi, nkhungu, etc., kumayambitsa mavuto osiyanasiyana kulephera PCBA
Chinyezi m'dera lakunja la zigawo zamagetsi PCB, pafupifupi zonse pali chiopsezo dzimbiri, amene madzi ndi yofunika kwambiri sing'anga dzimbiri, madzi mamolekyu ndi ang'onoang'ono mokwanira kudutsa mauna maselo kusiyana kwa zinthu polima mkati kapena kudzera. zitsulo zokutira kuti zifike pansi pa dzimbiri zachitsulo.Mpweya ukafika pachinyezi china, ukhoza kuyambitsa kusamuka kwa ma electrochemical PCB, kutayikira kwapano komanso kupotoza kwa ma siginecha pamabwalo apamwamba kwambiri.
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Mpweya/chinyezi + zoipitsa za ionic (mchere, ma flux active agents) = conductive electrolyte + stress voltage = electrochemical migration
Pamene RH mu mlengalenga ukufika 80%, padzakhala 5 mpaka 20 mamolekyu wandiweyani madzi filimu, mitundu yonse ya mamolekyu akhoza momasuka kusuntha, pamene pali mpweya, akhoza kupanga electrochemical anachita;RH ikafika pa 60%, pamwamba pa zidazo zimapanga filimu yamadzi yokhala ndi makulidwe a 2 mpaka 4 mamolekyu amadzi, ndipo zotsatira za mankhwala zidzachitika pamene zowononga zimasungunuka.Pamene RH <20% mu mlengalenga, pafupifupi onse dzimbiri zochitika kusiya;
Choncho, kuteteza chinyezi ndi gawo lofunika kwambiri la chitetezo cha mankhwala.
Pazida zamagetsi, chinyezi chimabwera m'njira zitatu: mvula, condensation, ndi nthunzi yamadzi.Madzi ndi electrolyte yomwe imatha kusungunula ma ion ambiri owononga omwe amawononga zitsulo.Pamene kutentha kwa gawo lina la zida ndi pansi pa "mame" (kutentha), padzakhala condensation pamwamba: zigawo structural kapena PCBA.
fumbi
Mumlengalenga muli fumbi, ndipo fumbi limatulutsa zonyansa za ion kuti zikhazikike mkati mwa zida zamagetsi ndikupangitsa kulephera.Izi ndizofala kwambiri pakulephera kwamagetsi pamunda.
Fumbi lagawidwa mitundu iwiri: fumbi coarse ndi kusakhazikika particles ndi awiri a 2.5 kuti 15 microns, amene kawirikawiri sayambitsa mavuto monga kulephera, arc, koma amakhudza kukhudzana cholumikizira;Fumbi labwino ndi tinthu tating'onoting'ono tokhala ndi mainchesi osakwana 2.5 microns.Fumbi labwino lili ndi zomatira pa PCBA (veneer) ndipo zitha kuchotsedwa ndi maburashi odana ndi malo amodzi.
Zowopsa za fumbi: a.Chifukwa cha fumbi kukhazikika pamwamba pa PCBA, electrochemical dzimbiri kwaiye, ndi kulephera mlingo wawonjezeka;b.Fumbi + yonyowa ponyowa kutentha + mchere kutsitsi ali kuwonongeka kwambiri PCBA, ndi kulephera pakompyuta zida kwambiri m'mphepete mwa nyanja, m'chipululu (saline-alkali dziko), ndi makampani mankhwala ndi madera migodi pafupi ndi Huaihe Mtsinje pa mildew ndi mvula nyengo. .
Choncho, chitetezo cha fumbi ndi mbali yofunika kwambiri ya chitetezo cha mankhwala.
Kupopera mchere
Mapangidwe a kutsitsi mchere: mchere kutsitsi amayamba ndi zinthu zachilengedwe monga mafunde, mafunde ndi kufalitsidwa mumlengalenga (monsoon) kuthamanga, kuwala kwa dzuwa, ndipo adzagwa kumtunda ndi mphepo, ndipo ndende yake amachepetsa ndi mtunda kuchokera gombe, kawirikawiri 1Km kuchokera. gombe ndi 1% ya gombe (koma mphepo yamkuntho idzawomba mopitirira).
Kuopsa kwa kupopera mchere: a.kuwononga ❖ kuyanika zitsulo structural zigawo;b.Kuchuluka kwa dzimbiri kwa electrochemical kumabweretsa kusweka kwa waya wachitsulo ndi kulephera kwazinthu.
Magwero a dzimbiri ofanana: a.Pali mchere, urea, lactic acid ndi mankhwala ena omwe ali m'manja mwa thukuta, omwe ali ndi zotsatira zowonongeka pa zipangizo zamagetsi monga kupopera mchere, kotero magolovesi ayenera kuvala panthawi ya msonkhano kapena ntchito, ndipo chophimbacho sichiyenera kukhudzidwa ndi manja opanda kanthu;b.Pali ma halogens ndi ma acid mu flux, omwe amayenera kutsukidwa ndikuwongolera ndende yake yotsalira.
Choncho, kupewa kupopera mchere ndi mbali yofunika ya chitetezo mankhwala.
nkhungu
Nkhungu, dzina lodziwika bwino la bowa wa filamentous, limatanthauza "bowa wankhungu," womwe umakonda kupanga mycelium wobiriwira, koma wosabala zipatso zazikulu ngati bowa.M'malo achinyezi komanso otentha, zinthu zambiri zimamera madera owoneka bwino, oyenda kapena akangaude, omwe ndi nkhungu.
PCB mold phenomenon
Kuopsa kwa nkhungu: a.nkhungu phagocytosis ndi kufalitsa kumapangitsa kutchinjiriza kwa zinthu organic kuchepa, kuwonongeka ndi kulephera;b.Ma metabolites a nkhungu ndi ma organic acid, omwe amakhudza kutsekemera ndi kukana kwamagetsi ndikupanga arc.
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Chifukwa chake, anti-mold ndi gawo lofunikira la chitetezo chazinthu.
Poganizira zomwe zili pamwambazi, kudalirika kwa mankhwalawa kuyenera kutsimikiziridwa bwino, ndipo kuyenera kudzipatula ku chilengedwe chakunja monga momwe kungathekere, kotero kuti mawonekedwe opaka mawonekedwe amayambitsidwa.
Pambuyo pakuphimba kwa PCB, kuwombera pansi pa nyali yofiirira, kuyanika koyambirira kungakhalenso kokongola kwambiri!
Kupaka utoto katatu kumatanthawuza mawonekedwe a PCB okutidwa ndi wosanjikiza wocheperako woteteza, pakali pano ndi njira yomwe imagwiritsidwa ntchito kwambiri popaka kuwotcherera pamwamba, yomwe nthawi zina imadziwika kuti ❖ kuyanika pamwamba, ❖ kuyanika mawonekedwe (Kupaka dzina lachingerezi, zokutira zofananira). ).Imalekanitsa zida zamagetsi zamagetsi kumadera ovuta, kuwongolera kwambiri chitetezo ndi kudalirika kwazinthu zamagetsi ndikukulitsa moyo wautumiki wazinthu.Zovala zosagwira katatu zimateteza mabwalo / zigawo kuzinthu zachilengedwe monga chinyezi, zowononga, dzimbiri, kupsinjika, kugwedezeka, kugwedezeka kwamakina ndi njinga zamatenthedwe, komanso kuwongolera mphamvu zamakina ndi kutchinjiriza kwa chinthucho.
Pambuyo pakuphimba, PCB imapanga filimu yotetezera yowonekera pamtunda, yomwe ingalepheretse bwino kulowetsedwa kwa mikanda yamadzi ndi chinyezi, kupewa kutayikira ndi kufupika.
2. Mfundo zazikuluzikulu za ndondomeko yokutira
Malinga ndi zofunikira za IPC-A-610E(Electronic Assembly Testing Standard), zimawonetsedwa makamaka m'magawo otsatirawa.
Complex PCB board
1. Malo omwe sangathe kukutidwa:
Madera omwe amafunikira kulumikizidwa kwamagetsi, monga mapepala agolide, zala zagolide, zitsulo kudzera m'mabowo, mabowo oyesera;Mabatire ndi mabatire okwera;Cholumikizira;Fuse ndi nyumba;Chipangizo chochotsera kutentha;Jumper waya;Magalasi a zida zowonera;Potentiometer;Sensor;Palibe chosindikizira chosindikizidwa;Malo ena omwe kupaka kungakhudze magwiridwe antchito kapena ntchito.
2. Madera omwe ayenera kuphimbidwa: zolumikizira zonse zogulitsira, zikhomo, zida zamagulu.
3. Malo omwe angathe kupenta kapena ayi
makulidwe
Makulidwe amayezedwa pa malo athyathyathya, osalephereka, ochiritsidwa pagawo losindikizidwa, kapena pa mbale yolumikizira yomwe imapangidwa ndi chigawocho.Bolodi lophatikizidwa likhoza kukhala lazinthu zofanana ndi bolodi losindikizidwa kapena zinthu zina zopanda porous, monga zitsulo kapena galasi.Muyezo wa makulidwe a filimu yonyowa ungagwiritsidwenso ntchito ngati njira yosankhira pakuyezera makulidwe a filimu, malinga ngati kutembenuka kwa filimu yowuma ndi yonyowa kulembedwa.
Table 1: Makulidwe osiyanasiyana amtundu uliwonse wazinthu zokutira
Njira yoyesera makulidwe:
1. Chida choyezera makulidwe a filimu yowuma: micrometer (IPC-CC-830B);b Dry Film Thickness Gauge (Iron base)
Micrometer youma filimu chida
2. Muyezo wa makulidwe a filimu yonyowa: Makulidwe a filimu yonyowa amatha kupezedwa ndi chiwopsezo cha makulidwe a filimu yonyowa, kenako kuwerengeredwa ndi kuchuluka kwa zolimba za guluu.
Makulidwe a filimu yowuma
The chonyowa filimu makulidwe akamagwira chonyowa filimu makulidwe gauge, ndiyeno youma filimu makulidwe amawerengedwa
Kusintha kwa m'mphepete
Tanthauzo: Muzochitika zachilendo, kupopera kwa valve yopopera kuchokera pamphepete mwa mzere sikudzakhala kowongoka kwambiri, padzakhala nthawi zonse burr.Timatanthawuza m'lifupi mwa burr ngati m'mphepete mwake.Monga momwe tawonetsera pansipa, kukula kwa d ndi mtengo wa chisankho cha m'mphepete.
Zindikirani: Kusanja kwa m'mphepete ndikocheperako bwinoko, koma zofunikira zamakasitomala zosiyanasiyana sizofanana, chifukwa chake mawonekedwe ophimbidwa malinga ndi zomwe makasitomala amafuna.
Kufananiza kwachitsulo cham'mphepete
Kufanana, guluu ayenera kukhala makulidwe yunifolomu ndi yosalala mandala filimu yokutidwa pa mankhwala, kugogomezera pa kufanana kwa guluu yokutidwa mankhwala pamwamba pa dera, ndiye ayenera kukhala makulidwe ofanana, palibe mavuto ndondomeko: ming'alu, stratification, mizere lalanje, kuipitsa, capillary phenomenon, thovu.
Axis basi AC mndandanda zodziwikiratu ❖ kuyanika makina ❖ kuyanika zotsatira, yunifolomu ndi zogwirizana kwambiri
3. Njira yokwaniritsira njira yopaka ndi kuphimba
Gawo 1 Konzani
Konzani zinthu ndi zomatira ndi zinthu zina zofunika;Dziwani komwe kuli chitetezo chapafupi;Dziwani zambiri za ndondomekoyi
Gawo 2 Sambani
Iyenera kutsukidwa pakangopita nthawi yochepa mutatha kuwotcherera kuti dothi lowotcherera lisakhale lovuta kuyeretsa;Dziwani ngati choipitsa chachikulu ndi polar kapena chopanda polar kuti musankhe choyeretsa choyenera;Ngati mankhwala oyeretsera mowa akugwiritsidwa ntchito, nkhani za chitetezo ziyenera kutsatiridwa: payenera kukhala bwino mpweya wabwino ndi kuzizira ndi kuumitsa ndondomeko pambuyo pa kutsuka, kuteteza kuphulika kwa zosungunulira zotsalira chifukwa cha kuphulika mu uvuni;Kuyeretsa madzi, kutsuka madzi ndi madzi oyeretsera zamchere (emulsion), ndiyeno muzitsuka madzi oyeretsera ndi madzi oyera kuti mukwaniritse kuyeretsa;
3. Chitetezo cha masking (ngati zida zopangira zosankhidwa sizikugwiritsidwa ntchito), ndiko kuti, chigoba;
Ayenera kusankha sanali zomatira filimu sangasinthe pepala tepi;Anti-static paper tepi iyenera kugwiritsidwa ntchito poteteza IC;Malingana ndi zofunikira za zojambula, zipangizo zina zimatetezedwa;
4.Deumidify
Pambuyo poyeretsa, PCBA yotetezedwa (gawo) iyenera kutayidwa kale ndi kuchotsedwa madzi musanaphike;Dziwani kutentha / nthawi yowumitsa chisanadze malinga ndi kutentha komwe kumaloledwa ndi PCBA (gawo);
Table 2: PCBA (zigawo) akhoza kuloledwa kudziwa kutentha / nthawi ya pre-kuyanika tebulo
Gawo 5 Ikani
The ndondomeko njira ❖ kuyanika zimadalira zofunika chitetezo PCBA, zida alipo ndondomeko ndi nkhokwe alipo luso, amene nthawi zambiri zimatheka m'njira zotsatirazi:
a.Sambani pamanja
Njira yojambula pamanja
Burashi ❖ kuyanika ndi njira kwambiri ambiri ntchito, oyenera kupanga ang'onoang'ono mtanda, PCBA kapangidwe ndi zovuta ndi wandiweyani, ayenera chishango chitetezo zofunika mankhwala ankhanza.Chifukwa kupaka kungathe kulamulira zokutira mwakufuna kwake, mbali zomwe siziloledwa kupenta sizidzaipitsidwa;Kugwiritsa ntchito burashi kwa zinthu zochepa, zoyenera pamtengo wapamwamba wa zokutira zamagulu awiri;Njira yotsuka ili ndi zofunika kwambiri kwa woyendetsa, ndipo zojambula ndi zofunikira zopaka ziyenera kugayidwa mosamala musanamangidwe, ndipo mayina a zigawo za PCBA akhoza kudziwika, ndipo zizindikiro zogwira maso ziyenera kuikidwa pazigawo zomwe siziloledwa. kukhala wokutidwa.Wogwiritsa ntchito saloledwa kukhudza pulagi yosindikizidwa ndi dzanja nthawi iliyonse kuti apewe kuipitsidwa;
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b.Kuviika ndi dzanja
Njira yokutira ya dip m'manja
Dongosolo la kuviika limapereka zotsatira zabwino kwambiri zokutira, kulola kuti yunifolomu, zokutira mosalekeza zigwiritsidwe ntchito ku gawo lililonse la PCBA.Dongosolo la kuviika la dip siloyenera zida za PCBA zokhala ndi ma capacitor osinthika, ma cores, ma potentiometer, ma cores ooneka ngati chikho ndi zida zina zosasindikizidwa bwino.
Zofunikira zazikulu za njira yopaka dip:
Sinthani mamasukidwe oyenera;Kuwongolera liwiro lomwe PCBA imakwezedwa kuteteza thovu kupanga.Kawirikawiri osapitirira 1 mita pa liwiro lachiwiri;
c.Kupopera mbewu mankhwalawa
Kupopera mbewu mankhwalawa ndi njira yomwe imagwiritsidwa ntchito kwambiri komanso yovomerezeka mosavuta, yomwe imagawidwa m'magulu awiri awa:
① Kupopera mbewu pamanja
Pamanja kupopera mbewu mankhwalawa dongosolo
Ndikoyenera kuti zinthu zogwirira ntchito zikhale zovuta kwambiri komanso zovuta kudalira zida zodzipangira zokhazokha, komanso ndizoyenera kuti mzere wa mankhwalawo uli ndi mitundu yambiri koma kuchuluka kwake ndi kochepa, ndipo akhoza kupopera. udindo wapadera.
Kupopera mbewu mankhwalawa pamanja kuyenera kudziwidwa: nkhungu ya penti idzaipitsa zida zina, monga mapulagi a PCB, soketi za IC, zolumikizirana tcheru ndi magawo ena oyambira, zigawozi ziyenera kulabadira kudalirika kwachitetezo chachitetezo.Mfundo ina ndi yakuti woyendetsa sayenera kukhudza pulagi yosindikizidwa ndi dzanja nthawi iliyonse kuti ateteze kuipitsidwa kwa malo okhudzana ndi pulagi.
② Kupopera mbewu mankhwalawa
Nthawi zambiri amatanthauza kupopera mbewu mankhwalawa ndi zida zosankhidwa bwino.Oyenera kupanga misa, kusasinthasintha bwino, kulondola kwambiri, kuwononga chilengedwe pang'ono.Ndi kukweza kwa makampani, kuwongolera kwa ndalama zogwirira ntchito komanso zofunikira zoteteza chilengedwe, zida zopopera mbewuzo zimasintha pang'onopang'ono njira zina zokutira.