Ungayixazulula kanjani inkinga ye-EMI kumklamo we-Multilayer PCB?

Uyazi ukuthi ungayixazulula kanjani inkinga ye-EMI lapho ukwakhiwa kwe-PCB enezingqimba eziningi?

Ake ngikutshele!

Ziningi izindlela zokuxazulula izinkinga ze-EMI.Izindlela zesimanje zokucindezelwa kwe-EMI zifaka: ukusebenzisa i-EMI suppression coating, ukukhetha izingxenye zokucindezela ze-EMI ezifanele kanye nomklamo wokulingisa we-EMI.Ngokusekelwe kusakhiwo esiyisisekelo se-PCB, leli phepha lixoxa ngomsebenzi wesitaki se-PCB ekulawuleni imisebe ye-EMI kanye namakhono okuklama kwe-PCB.

ibhasi lamandla

I-voltage jump jump ye-IC ingasheshiswa ngokubeka amandla afanele eduze kwephinikhodi yamandla ye-IC.Nokho, lokhu akukona ukuphela kwenkinga.Ngenxa yempendulo yemvamisa elinganiselwe ye-capacitor, akunakwenzeka ukuthi i-capacitor ikhiqize amandla e-harmonic adingekayo ukushayela okukhiphayo kwe-IC ngokuhlanzekile kubhendi yefrikhwensi egcwele.Ngaphezu kwalokho, i-voltage yesikhashana eyakhiwe ebhasini lamandla izobangela ukwehla kwamandla kagesi kuzo zombili iziphetho ze-inductance yendlela yokuxhuma.Lawa ma-voltage esikhashana ayimithombo yokuphazamiseka ye-EMI yemodi evamile.Singazixazulula kanjani lezi zinkinga?

Endabeni ye-IC ebhodini lethu lesifunda, isendlalelo samandla ezungeze i-IC singabhekwa njenge-capacitor enhle ye-high-frequency capacitor, engaqoqa amandla avuzwe yi-discrete capacitor enikeza amandla aphezulu-frequency okukhipha okuhlanzekile.Ukwengeza, i-inductance yesendlalelo samandla esihle sincane, ngakho-ke isignali yesikhashana ehlanganiswe yi-inductor nayo incane, ngaleyo ndlela inciphisa imodi evamile ye-EMI.

Yiqiniso, ukuxhumana phakathi kwesendlalelo sokuhlinzeka amandla kanye nephinikhodi ye-IC kagesi kufanele kube kufushane ngangokunokwenzeka, ngoba umkhawulo okhuphukayo wesiginali yedijithali uyashesha futhi uyashesha.Kungcono ukuyixhuma ngqo kuphedi lapho iphinikhodi yamandla e-IC ikhona, okudingeka kuxoxwe ngayo ngokwehlukana.

Ukuze ulawule i-EMI yemodi evamile, isendlalelo samandla kufanele sibe izingqimba zamandla eziklanywe kahle ukuze zisize ukuhlukana nokuba ne-inductance ephansi ngokwanele.Abanye abantu bangase babuze, kuhle kangakanani?Impendulo incike kungqimba lwamandla, okokusebenza phakathi kwezingqimba, kanye nemvamisa yokusebenza (okungukuthi, umsebenzi wesikhathi sokunyuka kwe-IC).Ngokuvamile, isikhala sezendlalelo zamandla singu-6mil, futhi isiphambano siyinto engu-FR4, ngakho-ke amandla alinganayo ngeyintshi yesikwele yamandla angaba ngu-75pF.Ngokusobala, lapho isikhala sesendlalelo sincane, i-capacitance inkulu.

Awekho amadivayisi amaningi anesikhathi sokukhuphuka esingu-100-300ps, kodwa ngokwezinga lamanje lokuthuthukiswa kwe-IC, amadivayisi anesikhathi sokukhuphuka kububanzi obungu-100-300ps azothola ingxenye ephezulu.Kumasekhethi anezikhathi zokukhuphuka ze-100 kuya kwezingu-300, isikhala sesendlalelo esingu-3 mil asisasebenzi ezinhlelweni eziningi.Ngaleso sikhathi, kuyadingeka ukusebenzisa ubuchwepheshe be-delamination nesikhala se-interlayer esingaphansi kwe-1mil, futhi esikhundleni se-dielectric ye-FR4 impahla enomthamo ophezulu we-dielectric.Manje, ama-ceramics namapulasitiki asebhodweni angahlangabezana nezidingo zokuklama ze-100 kuya ku-300ps amasekethe esikhathi sokukhuphuka.

Nakuba izinto ezintsha nezindlela zingase zisetshenziswe esikhathini esizayo, izifunda ezivamile ze-1 kuya ku-3 ns zesikhathi sokukhuphuka, izikhala zengqimba engu-3 kuya ku-6 mil, kanye nezinto ze-dielectric ze-FR4 ngokuvamile zanele ukuphatha ama-harmonics asezingeni eliphezulu nokwenza amasignali esikhashana abe phansi ngokwanele, okungukuthi. , imodi evamile EMI ingancishiswa phansi kakhulu.Kuleli phepha, isibonelo sokuklama sokupakishwa kwezingqimba ze-PCB sinikezwa, futhi isikhala sesendlalelo sithathwa njenge-3 kuya ku-6 mil.

ukuzivikela kwe-electromagnetic

Kusukela endaweni yokubuka yomzila wesignali, isu elihle lokubeka izingqimba kufanele kube ukubeka yonke imikhondo yesignali isendlalelo esisodwa noma eziningi, eziseduze nongqimba lwamandla noma indiza ephansi.Ngokunikezwa kwamandla, isu elihle lokubeka izingqimba kufanele libe ukuthi ungqimba lwamandla luseduze nendiza yaphansi, futhi ibanga phakathi kwesendlalelo samandla kanye nendiza yaphansi kufanele ibe mncane ngangokunokwenzeka, okuyilokho esikubiza ngokuthi isu "lokwendlalela".

Isitaki se-PCB

Iluphi uhlobo lwesu lokupakisha olungasiza ukuvikela nokucindezela i-EMI?Uhlelo olulandelayo lokunqwabelanisa olunezendlalelo luthatha ukuthi amandla akhona ageleza kusendlalelo esisodwa nokuthi i-voltage eyodwa noma ama-voltage amaningi asatshalaliswa ezingxenyeni ezihlukene zesendlalelo esifanayo.Indaba yezendlalelo zamandla amaningi izoxoxwa kamuva.

4-ply plate

Kunezinkinga ezingase zibe khona ekwakhiweni kwama-4-ply laminates.Okokuqala, noma ngabe ungqimba lwesignali lusengqimbeni yangaphandle futhi amandla nendiza engaphansi kusendlalelo sangaphakathi, ibanga phakathi kongqimba lwamandla kanye nendiza ephansi liselikhulu kakhulu.

Uma imfuneko yezindleko ingeyokuqala, izindlela ezimbili ezilandelayo zebhodi le-4-ply lendabuko zingacatshangelwa.Zombili zingathuthukisa ukusebenza kokucindezela kwe-EMI, kodwa zifaneleka kuphela esimweni lapho ukuminyana kwezingxenye ebhodini kuphansi ngokwanele futhi kunendawo eyanele ezungeze izingxenye (ukubeka i-copper edingekayo ukuze kunikezwe amandla).

Esokuqala isikimu esithandwayo.Izendlalelo zangaphandle ze-PCB zonke ziyizendlalelo, futhi izingqimba ezimbili ezimaphakathi ziyizingqimba zesignali / zamandla.Ukunikezwa kwamandla kusendlalelo sesiginali kuhanjiswa ngemigqa ebanzi, okwenza ukuthi indlela yokuphakelwa kwamandla ibe phansi manje kanye nokuthikamezeka kwendlela yesignali ye-microstrip ibe phansi.Ngokombono wokulawula kwe-EMI, lesi yisakhiwo se-PCB esendlalelo esingcono kakhulu esingu-4 esitholakalayo.Ohlelweni lwesibili, ungqimba lwangaphandle luphethe amandla nomhlabathi, kanti ungqimba olubili oluphakathi luphethe isignali.Uma kuqhathaniswa nebhodi lendabuko elinezingqimba ezi-4, ukuthuthukiswa kwalolu hlelo kuncane, futhi i-impedance ye-interlayer ayilungile njengaleyo yebhodi yendabuko engu-4.

Uma i-wiring impedance kufanele ilawulwe, uhlelo lokupakisha olungenhla kufanele luqaphele kakhulu ukubeka i-wiring ngaphansi kwesiqhingi sethusi sokuhlinzekwa kwamandla kanye nokubeka phansi.Ngaphezu kwalokho, isiqhingi sethusi ekunikezeni amandla noma i-stratum kufanele sixhunywe ngangokunokwenzeka ukuze kuqinisekiswe ukuxhumana phakathi kwe-DC kanye nemvamisa ephansi.

6-ply plate

Uma ukuminyana kwezingxenye ebhodini le-4-layer likhulu, ipuleti le-6-layer lingcono.Kodwa-ke, umphumela wokuvikela wezinye izinhlelo zokupakisha ekwakhiweni kwebhodi lezingqimba ezi-6 awulungile ngokwanele, futhi isignali yesikhashana yebhasi yamandla ayincishisiwe.Izibonelo ezimbili kuxoxwa ngazo ngezansi.

Esimweni sokuqala, ukunikezwa kwamandla kanye nomhlabathi kubekwa ezingxenyeni zesibili nesesihlanu ngokulandelana.Ngenxa yokuvinjelwa okuphezulu kwamandla e-copper clad, akukuhle kakhulu ukulawula imisebe ye-EMI yemodi evamile.Nokho, ngokombono wokulawula isignali impedance, le ndlela ilungile kakhulu.

Esibonelweni sesibili, ukunikezwa kwamandla kanye nomhlabathi kubekwa kwesesithathu nesesine ngokulandelana.Lo mklamo uxazulula inkinga ye-copper clad impedance yokunikezwa kwamandla.Ngenxa yokusebenza kabi kokuvikela kazibuthe kwe-electromagnetic kwesendlalelo 1 nosendlalelo 6, imodi yokuhlukanisa i-EMI iyakhula.Uma inombolo yemigqa yesignali ezingxenyeni ezimbili zangaphandle incane futhi ubude bemigqa bufushane kakhulu (ngaphansi kwe-1 / 20 ye-wavelength ephakeme kakhulu ye-harmonic yesiginali), umklamo ungaxazulula inkinga yemodi yokuhlukanisa i-EMI.Imiphumela ibonisa ukuthi ukucindezelwa kwemodi yokuhlukanisa i-EMI kuhle ikakhulukazi lapho ungqimba lwangaphandle lugcwaliswa ngethusi futhi indawo eboshwe ngethusi igxiliwe (njalo nge-1 / 20 wavelength interval).Njengoba kushiwo ngenhla, ithusi kufanele libekwe


Isikhathi sokuthumela: Jul-29-2020