Pamapangidwe a PCB, electromagnetic compatibility (EMC) ndi kusokonezedwa kwa electromagnetic (EMI) kale kwakhala mitu iwiri yayikulu kwa mainjiniya, makamaka pamapangidwe a board ozungulira masiku ano komanso ma phukusi azinthu akupitilira kuchepa, ma OEM amafunikira makina othamanga kwambiri.M'nkhaniyi, ndigawana momwe mungapewere zovuta zamagetsi pamapangidwe a PCB.
1. Crosstalk ndi kuyanjanitsa ndiko kulunjika
Kuyanjanitsa ndikofunikira kwambiri kuti zitsimikizire kuyenda koyenera kwapano.Ngati zamakono zimachokera ku oscillator kapena chipangizo china chofanana, ndikofunika kwambiri kuti pakali pano pakhale kusiyana ndi pansi, kapena kuti pakali pano zisayende molingana ndi kusintha kwina.Zizindikiro ziwiri zothamanga kwambiri zofananira zimatha kupanga EMC ndi EMI, makamaka crosstalk.Ndikofunikira kusunga njira zopinga kukhala zazifupi momwe mungathere komanso njira zobwereranso kukhala zazifupi momwe mungathere.Kutalika kwa njira yobwerera kumayenera kukhala yofanana ndi kutalika kwa njira yotumizira.
Kwa EMI, njira imodzi imatchedwa "njira yophwanya malamulo" ndipo ina ndi "njira yozunzidwa".Inductive ndi capacitive coupling imakhudza njira ya "wozunzidwa" chifukwa cha kukhalapo kwa ma electromagnetic fields, motero kumapanga mafunde a kutsogolo ndi kumbuyo kwa "njira yozunzidwa".Mwanjira iyi, ripple imapangidwa m'malo okhazikika pomwe kutumizira ndi kulandira kutalika kwa chizindikiro kumakhala pafupifupi kofanana.
M'malo abwino okhala ndi ma mayendedwe okhazikika, mafunde omwe apangitsidwa ayenera kuletsana, motero amachotsa crosstalk.Komabe, tili m’dziko lopanda ungwiro limene zinthu zoterezi sizichitika.Chifukwa chake, cholinga chathu ndichakuti crosstalk iyenera kukhala yochepa pamayendedwe onse.Zotsatira za crosstalk zitha kuchepetsedwa ngati m'lifupi pakati pa mizere yofananira ndi iwiri m'lifupi mwake.Mwachitsanzo, ngati m'lifupi mwake mzere ndi 5 mils, mtunda wochepera pakati pa mizere iwiri yofananira uyenera kukhala 10 mils kapena kupitilira apo.
Pamene zipangizo zatsopano ndi zigawo zikupitiriza kuonekera, opanga PCB ayenera kupitirizabe kuthana ndi EMC ndi zosokoneza.
2. Decoupling capacitors
Decoupling capacitors amachepetsa zotsatira zosafunikira za crosstalk.Ayenera kukhala pakati pa mphamvu ndi zikhomo pansi pa chipangizocho, zomwe zimatsimikizira kuti AC impedance yotsika komanso kuchepetsa phokoso ndi crosstalk.Kuti mukwaniritse kutsika kwapang'onopang'ono pama frequency angapo, ma decoupling capacitor angapo ayenera kugwiritsidwa ntchito.
Mfundo yofunikira pakuyika ma capacitors ophatikizika ndikuti capacitor yokhala ndi mtengo wotsika kwambiri imayikidwa pafupi ndi chipangizocho momwe mungathere kuti muchepetse zotsatira zoyeserera pamalumikizidwe.Capacitor iyi iyenera kuyikidwa pafupi kwambiri ndi zikhomo zopangira mphamvu za chipangizocho kapena msewu wamagetsi wamagetsi ndipo mapepala a capacitor ayenera kulumikizidwa mwachindunji ku vias kapena pansi.Ngati kuyanjanitsako kuli kwautali, gwiritsani ntchito njira zingapo kuti muchepetse kutsekeka kwa nthaka.
3. Kuyika PCB
Njira yofunikira yochepetsera EMI ndiyo kupanga gawo la PCB.Chinthu choyamba ndikupangitsa malo oyambira kukhala aakulu momwe angathere mkati mwa gulu lonse la PCB kuti mpweya, crosstalk ndi phokoso zichepetse.Chisamaliro chapadera chiyenera kuchitidwa pogwirizanitsa chigawo chilichonse ku malo apansi kapena pansi, popanda zomwe zotsatira za neutralizing za nthaka yodalirika sizingagwiritsidwe ntchito mokwanira.
Mapangidwe ovuta kwambiri a PCB ali ndi ma voltages angapo okhazikika.Moyenera, voliyumu iliyonse yowunikira imakhala ndi gawo lake loyambira.Komabe, magawo ambiri oyambira amatha kukulitsa mtengo wopanga PCB ndikupangitsa kuti ikhale yokwera mtengo kwambiri.Kugwirizana ndiko kugwiritsa ntchito magawo oyambira m'malo atatu kapena asanu, omwe amatha kukhala ndi magawo angapo oyambira.Izi sizimangowongolera mtengo wopangira bolodi, komanso zimachepetsa EMI ndi EMC.
Dongosolo lotsika loyimitsa loyimitsa ndikofunikira ngati EMC ikuyenera kuchepetsedwa.Mu multilayer PCB ndikwabwino kukhala ndi maziko odalirika m'malo mokhala ndi chotchinga chamkuwa (kuba zamkuwa) kapena malo obalalika chifukwa ali ndi njira yocheperako, imapereka njira yamakono komanso gwero labwino kwambiri lazizindikiro zobwerera.
Kutalika kwa nthawi yomwe chizindikirocho chimatenga kubwerera pansi ndikofunikanso kwambiri.Nthawi yotengedwa kuti chizindikirocho chiyende ndi kuchoka ku gwero chiyenera kufanana, mwinamwake chodabwitsa chofanana ndi mlongoti chidzachitika, kulola mphamvu yowunikira kukhala gawo la EMI.Mofananamo, kuyanjanitsa kwa panopa ku / kuchokera ku gwero la chizindikiro kuyenera kukhala kwaufupi momwe zingathere, ngati gwero ndi njira zobwerera sizili zofanana, kuphulika kwapansi kudzachitika ndipo izi zidzapanganso EMI.
4. Pewani ngodya za 90 °
Kuti muchepetse EMI, kuyanjanitsa, ma vias ndi zigawo zina ziyenera kupewedwa kuti apange ngodya ya 90 °, chifukwa ngodya yoyenera idzatulutsa ma radiation.Pofuna kupewa ngodya ya 90 °, kuyanjanitsa kuyenera kukhala mawaya awiri a 45 ° pakona.
5. Kugwiritsa ntchito bowo kumayenera kusamala
Pafupifupi masanjidwe onse PCB, vias ayenera kugwiritsidwa ntchito kupereka kugwirizana conductive pakati pa zigawo zosiyanasiyana.Nthawi zina, iwonso kutulutsa zowonetsera, monga khalidwe impedance kusintha pamene vias analengedwa mu mayikidwe.
M'pofunikanso kukumbukira kuti vias kuonjezera kutalika kwa mayikidwe ndi ayenera zikugwirizana.Pankhani ya kuyanjanitsa kosiyana, ma vias ayenera kupewedwa ngati kuli kotheka.Ngati izi sizingapewedwe, vias iyenera kugwiritsidwa ntchito m'njira zonse ziwiri kuti athe kubweza kuchedwa kwa chizindikiro ndi njira zobwerera.
6. Zingwe ndi chitetezo chakuthupi
Zingwe zonyamula mabwalo a digito ndi mafunde a analogue zimatha kupanga ma parasitic capacitance ndi inductance, zomwe zimayambitsa zovuta zambiri zokhudzana ndi EMC.Ngati zingwe zopotoka zikugwiritsidwa ntchito, kuphatikizika kochepa kumasungidwa ndipo maginito opangidwa amachotsedwa.Pazidziwitso zapafupipafupi, zingwe zotetezedwa ziyenera kugwiritsidwa ntchito, kutsogolo ndi kumbuyo kwawo, kuti athetse kusokoneza kwa EMI.
Kuteteza thupi ndi kutsekereza zonse kapena gawo la dongosolo mu phukusi lachitsulo kuti EMI isalowe mu PCB.Kutchinjiriza uku kumachita ngati chotseka, choyendetsa pansi, kuchepetsa kukula kwa lupu la mlongoti ndikuyamwa EMI.
Nthawi yotumiza: Nov-23-2022