Ungayixazulula kanjani inkinga ye-EMI ekwakhiweni kwe-Multilayer PCB?

Uyazi ukuthi ungayixazulula kanjani inkinga ye-EMI lapho kudalwa ama-PCB amaningi?

Ake ngikutshele!

Kunezindlela eziningi zokuxazulula izinkinga ze-EMI. Izindlela zokucindezela ze-EMI zanamuhla zifaka: ukusebenzisa i-EMI yokucindezelwa kokugaya, ukukhetha izingxenye ezifanele zokucindezela ze-EMI kanye nomklamo wekulingisa we-EMI. Kususelwa esimisweni esiyisisekelo se-PCB, leli phepha lidingida umsebenzi wesitaki se-PCB ekulawuleni imisebe ye-EMI namakhono wokwenza kwe-PCB.

ibhasi lamandla

Ukuqhuma kwamandla kagesi we-IC kungasheshiswa ngokubeka amandla afanele eduze kwephini lamandla le-IC. Kodwa-ke, lokhu akukhona ukuphela kwenkinga. Ngenxa yokuphendula okuvunyelwe kwe-capacitor, akunakwenzeka ukuthi i-capacitor ikhiqize amandla e-harmonic adingekayo ukushayela okukhipha i-IC ngokuhlanzekile ebhendi yemvamisa egcwele. Ngaphezu kwalokho, i-voltage yesikhashana eyakhiwe ebhasini lamandla izodala ukwehla kwamandla kagesi emikhawulweni yomibili yokungenzi kwendlela yokuncipha. Lezi zikhathi zokuthambekela zesikhashana ziyimithombo yokuphazamisa evamile yemodi ye-EMI. Singazixazulula kanjani lezi zinkinga?

Esimweni se-IC ebhodini lethu lesifunda, ungqimba wamandla azungeze i-IC ungabukwa njenge-capacitor ephezulu yesikhathi esivamile, engaqoqa amandla avuthwe yi-discrete capacitor enikeza amandla amvamisa aphezulu wokukhipha okuhlanzekile. Ngaphezu kwalokho, ukungeniswa kwesendlalelo esihle samandla kuncane, ngakho-ke isignali yesikhashana eyenziwe yi-inductor nayo incane, ngaleyo ndlela inciphisa imodi ejwayelekile ye-EMI.

Vele, ukuxhumana phakathi kwesendlalelo sokuphakelwa kukagesi kanye nephini yokunikezwa kwamandla kwe-IC kufanele kube kufushane ngangokunokwenzeka, ngoba umkhawulo okhuphukayo wesiginali yedijithali uyashesha futhi uyashesha. Kungcono ukuyixhuma ngqo epanini lapho kutholakala khona ipin yamandla e-IC, edinga ukuxoxwa ngokwahlukana.

Ukuze ulawule imodi ejwayelekile ye-EMI, ungqimba wamandla kufanele kube izendlalelo zamandla kagesi ezidizayinwe kahle ukuze zisize ukuhlahlela futhi zibe ne-inductance ephansi ngokwanele. Abanye abantu bangase babuze, ukuthi kuhle kanjani? Impendulo incike kusendlalelo yamandla, okuqukethwe okuphakathi kwezendlalelo, nemvamisa yokusebenza (ie, umsebenzi wesikhathi sokukhuphuka kwe-IC). Ngokuvamile, ukuhlukaniswa kwezendlalelo zamandla kungu-6mil, kanti i-interlayer iyizinto ze-FR4, ngakho-ke amandla alinganayo ngamasentimitha ayisithupha wesendlalelo samandla cishe angama-75pF. Ngokusobala, njengoba kuncane ukwanda kwesendlalelo, kukhulu ubukhulu bawo.

Awekho amadivayisi amaningi anesikhathi sokuphakama kwe-100-300ps, kepha ngokwesilinganiso samanje sokuthuthuka kwe-IC, amadivayisi anesikhathi sokukhuphuka ebangeni le-100-300ps azoba nenani eliphezulu. Okomjikelezo onezikhathi ezikhuphuka ze-100 kuye kwezingama-300 ze-PS, ukuhlukaniswa kwesikhala okungu-3 mil akusasebenzi kwizicelo eziningi Ngaleso sikhathi, kuyadingeka ukwamukela ubuchwepheshe be-delamination nge-interlayer spatula esingaphansi kwe-1mil, bese ubuyisela impahla ye-di4 ye-di4 ye-dielectric ngento leyo nge-dielectric ephezulu engaguquki. Manje, izinto zobumba kanye namapulasitiki anezimbiza angahlangabezana nezidingo zokwakheka kwama-circuits wesikhathi sokuphakama ayi-100 kuye ku-300ps.

Yize izinsiza nezindlela ezintsha zingasetshenziswa esikhathini esizayo, ukujikeleza okuvamile okungu-1 kuye ku-3 ns ukukhuphuka kwesikhala, izikhala ezi-3 kuye kwezi-6 cm, izendlalelo, kanye nezinto ezisetshenziswayo ze-di4 di4. , imodi ejwayelekile EMI ingancishiswa iphansi kakhulu. Kuleli phepha, isibonelo sokuklanywa se-PCB layered stacking sinikezwa, futhi izikhala zesendlalelo zithathwa njengezi-3 kuye kwezi-6 mil.

ukuvikelwa kwe-electromagnetic

Ngokombono womzila wesiginali, isu elihle lokubeka kufanele kube ukubeka yonke imikhondo yesigcawu kusendlalelo esisodwa noma ngaphezulu, esiseduze kongqimba lwamandla noma indiza yaphansi. Ngokuphakelwa kukagesi, isu elihle lokubeka kufanele kube ukuthi ungqimba lwamandla lusondele endizeni yaphansi, futhi ibanga phakathi kongqimba wamandla nendiza yasemhlabeni kufanele libe lincane ngangokunokwenzeka, okuyilokho esikubiza ngokuthi isu “lokubeka”.

Isitaki sePCB

Hlobo luni lweqhinga lokunqwabelana elingasiza ukuvikela nokucindezela i-EMI? Isikimu esilandelwayo sokubeka esilinganisweni sicabangela ukuthi amandla okuhambisa yamanje ageleza kusendlalelo eyodwa nokuthi i-voltage eyodwa noma ama-voltages amaningi asatshalaliswa ezingxenyeni ezihlukile zeleya efanayo. Icala lezendlalelo zamandla eziningi lizoxoxwa ngokuhamba kwesikhathi.

4-ply ipuleti

Kunezinkinga ezithile ezingaba khona ekwakhiweni kwama-4-ply laminates. Okokuqala, noma ngabe ungqimba lwesiginali ungqimba lwangaphandle futhi amandla namaplanethi omhlaba aku-ungqimba ongaphakathi, ibanga phakathi kongqimba lwamandla neplanethi yomhlaba liselikhulu kakhulu.

Uma isidingo sezindleko singesokuqala, izindlela ezimbili ezilandelayo zebhodi le-4-ply yendabuko zingabhekwa. Zombili zingathuthukisa ukusebenza kokucindezelwa kwe-EMI, kepha zilungele icala kuphela lapho ubukhulu bezinto ebhodini buphansi ngokwanele futhi kunendawo eyanele ezungeze izingxenye (ukubeka ingubo yethusi edingekayo yokuphakelwa kwamandla).

Eyokuqala uhlelo olukhethwayo. Izendlalelo zangaphandle ze-PCB zonke zingqimba, kanti izingqimba ezimbili eziphakathi ziyizingqimba / izendlalelo zamandla. Ukunikezwa kwamandla kusendlalelo sesiginali kuhanjiswa ngemigqa ebanzi, okwenza i-impedance yendlela yokunikezwa kwamandla ibe phansi manje kanye ne-impedance yendlela yesiginali ye-microstrip iphansi. Ngokombono wokulawulwa kwe-EMI, lesi yisakhiwo se-PCB esingcono kakhulu esingu-4 esitholakalayo. Ohlelweni lwesibili, ungqimba lwangaphandle luphethe amandla nomhlabathi, kuthi ungqimba olwesibili oluphethe isiginali. Uma kuqhathaniswa nebhodi yendabuko enezingqimba ezi-4, ukwenziwa ngcono kwalolu hlelo kuncane, futhi i-interlayer impedance ayifani naleyo yebhodi lendabuko elinezinhla ezi-4.

Uma umgoqo we-wiring uzolawulwa, uhlelo olungenhla lokufaka kufanele luqaphele kakhulu ukubeka i-wiring ngaphansi kwesiqhingi sethusi sokuhlinzekwa kwamandla nokusika phansi. Ngaphezu kwalokho, isiqhingi sethusi ekunikezelweni kwamandla noma kuhlaka kufanele sixhunyaniswe ngangokunokwenzeka ukuqinisekisa ukuxhumana phakathi kweDC nemvamisa ephansi.

Ipuleti le-6-ply

Uma ubukhulu bezingxenye ezisebhodini lezendlalelo ezi-4 likhulu, ipuleti elingububanzi obungu-6 lingcono. Kodwa-ke, umphumela wokuvikela ezinye izikimu zokufaka isitaki ekwakhiweni kwebhodi enezingqimba eziyi-6 awanele ngokwanele, futhi isignali yesikhashana yebhasi lamandla ayincishisiwe. Izibonelo ezimbili kuxoxwa ngazo ngezansi.

Esimweni sokuqala, ukuhanjiswa kwamandla kanye nomhlabathi kubekwa engxenyeni yesibili neyesihlanu ngokulandelana. Ngenxa yokuphazamiseka okuphezulu kokuhlinzekwa kwamandla kagesi ethusi, akulungile neze ukulawula imisebe ye-EMI ejwayelekile. Kodwa-ke, kusukela endaweni yokubuka yokulawulwa kokuvinjezelwa kwezibonakaliso, le ndlela ilungile kakhulu.

Esibonelweni sesibili, ukuhanjiswa kwamandla kanye nomhlabathi kubekwa engxenyeni yesithathu neyesine ngokulandelana. Lo mklamo uxazulula inkinga yethusi egqoke i-impedance yamandla kagesi. Ngenxa yokusebenza kwe-electromagnetic evikelekile kungqimba 1 no-safu 6, imodi yokuhlukanisa i-EMI iyanda. Uma inani lemigqa yesiginali kuzendlalelo ezimbili zangaphandle lincane futhi ubude bemigqa bufushane kakhulu (ngaphansi kuka-1/20 wobude be-harmonic ephezulu yesiginali), idizayini ingaxazulula inkinga yemodi yokuhlukahluka EMI. Imiphumela ikhombisa ukuthi ukucindezelwa kwemodi yokuhlukanisa i-EMI muhle kakhulu lapho ungqimba lwangaphandle lugcwele ngobhedu futhi indawo yamagqabha ethusi isuswa (njalo nge-1/20 i-wavelength disc). Njengoba kushiwo ngenhla, ithusi lizobekwa


Isikhathi sokuthumela: Jul-29-2020