Momwe mungathetse vuto la EMI mu kapangidwe ka PCB ya Multilayer?

Kodi mukudziwa momwe mungathetsere vuto la EMI mukamapanga ma PCB angapo?

Ndikuuzeni!

Pali njira zambiri zothetsera mavuto a EMI. Njira zamakono zoponderezera za EMI zikuphatikiza: kugwiritsa ntchito zokutira za EMI kuphatikiza, kusankha magawo oyenera a EMI opondera ndi kapangidwe ka EMI. Kutengera ndi mawonekedwe a PCB ofunika kwambiri, pepalali likufotokoza ntchito ya PCB stack pakuwongolera ma radiation a EMI ndi luso la kapangidwe ka PCB.

basi yamagetsi

Kutulutsa kwamphamvu kwa IC kumatha kupitilizidwa pakuyika mphamvu yoyenera pafupi ndi pini yamagetsi ya IC. Komabe, awa sindiwo mathero avutoli. Chifukwa cha kuchepa pafupipafupi kwa capacitor, sikungatheke kuti capacitor ipangitse mphamvu zowunikira zomwe zimafunikira kuyendetsa kutulutsa kwa IC mowonera bwino. Kuphatikiza apo, ma voliyumu osakhalitsa opangidwa m'basi yamagetsi amadzetsa kugwa kwamagetsi kumapeto onse a njira yolowera. Ma voltages osakhalitsa ndiwo magwero ofala akusokonezedwa ndi EMI. Kodi tingathetse bwanji mavutowa?

Pankhani ya IC pa komiti yathu yadera, zigawo zamagetsi kuzungulira IC zimatha kuonedwa ngati capacitor yabwino kwambiri, yomwe imatha kusonkhanitsa mphamvu yomwe idatsitsidwa ndi discrete capacitor yomwe imapereka mphamvu pafupipafupi pakuyipitsa. Kuphatikiza apo, kusunthika kwa gawo labwino lamphamvu ndizochepa, kotero siginecha yochepa yomwe imapangidwa ndi inductor imakhalanso yochepa, motero kuchepetsa njira wamba EMI.

Zachidziwikire, kulumikizana pakati pazosanjikiza zamagetsi ndi pini yamagetsi ya IC kuyenera kukhala kofupikirapo momwe zingathere, chifukwa kuwonjezeka kwa chizindikiro cha digito ndikofulumira komanso mwachangu. Ndikwabwino kulumikiza molunjika ndi pesi pomwe pali pini yamphamvu ya IC, yomwe imafunika kukambirana padera.

Pofuna kuwongolera mawonekedwe wamba a EMI, mphamvu yamagetsi iyenera kukhala yopangidwa mwaluso kwambiri kuti izithandiza kusokonekera ndikukhala ndi kuchepa kokwanira. Anthu ena angafunse kuti, zili bwanji? Yankho limatengera mphamvu yamagetsi, zinthu zomwe zili pakati pa zigawo, komanso ma frequency ogwiritsira ntchito (mwachitsanzo, ntchito ya IC ikukwera nthawi). Mwambiri, katayanitsidwe ka zigawo zamagetsi ndi 6mil, ndipo wopikirako ndi FR4 zakuthupi, kotero capacitance yofanana pa inchi imodzi yayikulu yamphamvu ndi pafupifupi 75pF. Mwachiwonekere, chocheperako chimatalikirana, ndizochulukirapo.

Palibe zida zambiri zokhala ndi nthawi yokwera 100-300ps, koma malinga ndi kuchuluka kwakukula kwa IC, zida zomwe zimakhala ndi nthawi yokwera 100-300ps zidzakhala zochuluka kwambiri. Kwa ma circuits okhala ndi 100 mpaka 300 nthawi yakukwera PS, katemera wosanjikiza wa 3 mil sagwiranso ntchito pazinthu zambiri. Panthawiyo, ndikofunikira kutengera tekinoloji ya delamination yokhala ndi malo ena ochepera 1mil, ndikusintha mawonekedwe a FR4 dielectric ndi zinthuzo ndi dielectric yambiri. Tsopano, ziwiya zadothi ndi mapulasitiki opangidwa ndi potted amatha kukwaniritsa zofunikira pakapangidwe ka ma 100 mpaka 300ps ma circuits of time.

Ngakhale zida zatsopano ndi njira zingagwiritsidwe ntchito mtsogolomo, 1 mpaka 3 ns maulendo akwera, 3 mpaka 6 mil wosanjikiza, ndi zida za dielectric za FR4 nthawi zambiri zimakhala zokwanira kuthana ndi ma harmoniki akumapeto ndikupanga zizindikiritso zazifupi zokwanira, ndiko kuti , mode wamba EMI ikhoza kuchepetsedwa kwambiri. Mu pepala ili, kapangidwe ka PCB kosanjikiza kamaperekedwa, ndipo kutalikirana kwake kumayesedwa kukhala 3 mpaka 6 mil.

electromagnetic chitetezo

Kuchokera pamawonekedwe a ma siginolo, njira yabwino yoyika iyenera kukhala kuyika zizindikilo zonse gawo limodzi kapena angapo, omwe ali pafupi ndi magetsi kapena ndege yapansi. Pogwiritsa ntchito magetsi, njira yabwino yoyika magetsi iyenera kukhala kuti mphamvu yamagetsi ili pafupi ndi ndege yapansi, ndipo mtunda pakati pa chingwe chamagetsi ndi ndege yapansi iyenera kukhala yaying'ono momwe zingathere, zomwe timazitcha "kuyala".

PCB stack

Kodi ndi njira yanji yomwe ikusungunulira yomwe ingathandize kuteteza ndi kupondera EMI? Ndondomeko yotsatirayi yokhayokha imaganiza kuti magetsi omwe akuyenda pakadali pano amayenda mosanjikiza kamodzi ndikuti magetsi amodzi kapena ma voltages angapo amagawidwa m'malo osiyanasiyana. Nkhani yamagulu angapo amagetsi idzakambidwa pambuyo pake.

4-ply mbale

Pali zovuta zina pakupanga ma 4-ply laminates. Choyamba, ngakhale ngati mzere wa chizindikiro uli m'mbali zakunja ndipo mphamvu ndi ndege za pansi zili m'zigawo zamkati, mtunda pakati pautali wamphamvu ndi ndege ya pansi udakali waukulu kwambiri.

Ngati mtengo wofunikirayo ndi woyamba, njira ziwiri zotsatirazi pa bolodi la 4-ply zitha kuganiziridwa. Onsewa amatha kukonza magwiridwe antchito a EMI, koma ndi oyenera pokhapokha ngati kachulukidwe ka zinthu zomwe zili pa bolodi ndizochepa kwambiri ndipo kuli malo okwanira kuzungulira zigawozo (kuyika zotengera zamkuwa zamkuwa).

Choyamba ndi chiwembu chomwe amakonda. Zigawo zakunja za PCB zonse ndizigawo, ndipo zigawo ziwiri zapakati ndizizindikiro / zamphamvu. Mphamvu yamagetsi pamizere yoyendera imayenda ndi mizere yotakata, zomwe zimapangitsa njira kutsekeka kwa magetsi kutsikira pakali pano komanso kutsekeka kwa chizindikiro cha microstrip kutsika. Kuchokera pakuwona kwa EMI yoyang'anira, iyi ndiye mawonekedwe abwino kwambiri a PCB omwe alipo. Mu chiwembu chachiwiri, gawo lakunja limanyamula mphamvu ndi nthaka, ndipo mawonekedwe awiri apakati amanyamula chizindikirocho. Poyerekeza ndi bolodi yachikale ya masanjidwe anayi, kukonza kwa chiwembuchi kumakhala kocheperako, ndipo kulowetsedwa sikungakhale koyenera ngati bolodi yachikhalidwe ya 4.

Ngati njira yolumikizira waya ikuyenera kuwongoleredwa, chiwembu chomwe chili pamwambachi chikuyenera kukhala chosamala kuyika zingwe pansi pachilumba chamkuwa cha magetsi ndi kukhazikika. Kuphatikiza apo, chilumba chamkuwa chopanga mphamvu zamagetsi kapena ma stratum ziyenera kulumikizidwa momwe zingathere kuti zitsimikizike kulumikizana pakati pa DC ndi pafupipafupi.

6-ply mbale

Ngati kachulukidwe ka zinthu zomwe zili pa 4-board board ndi zokulirapo, mbale 6 yokhala ndi gawo ndiyabwino. Komabe, zotchinga za mapulani ena osakanikirana pakapangidwe ka board 6 sikabwino, ndipo siginito yochepa basi ya magetsi sinachepetsedwe. Zitsanzo ziwiri zafotokozedwa pansipa.

Poyambirira, magetsi ndi nthaka zimayikidwa mu zigawo zachiwiri ndi zachisanu motsatana. Chifukwa cha kuchuluka kwamagetsi kwamagetsi okutidwa ndi mkuwa, ndizosavomerezeka kuwongolera ma radiation wamba a EMI. Komabe, pakuwona kwa kuwongolera ma impedance yama siginecha, njirayi ndiyolondola kwambiri.

Mu chitsanzo chachiwiri, magetsi ndi nthaka zimayikidwa mu zigawo zachitatu ndi zinayi motsatana. Kapangidwe kameneka kamathetsa vuto lamkuwa wonyezimira wamagetsi. Chifukwa cha chitetezo chosaoneka bwino cha electromagnetic cha wosanjikiza 1 ndi wosanjikiza 6, EMI yosiyanitsa imachulukirachulukira. Ngati kuchuluka kwa mzere wazizindikiro pazigawo ziwiri zakunja ndi kocheperako komanso kutalika kwa mizereyo ndizochepa kwambiri (chochepera 1/20 mwatsatanetsatane wapamwamba wa chizindikiro), mapangidwewo atha kuthetsa vuto la mtundu wosiyana wa EMI. Zotsatira zikuwonetsa kuti kuponderezedwa kwa mtundu wosiyana EMI ndikwabwino kwambiri pamene gawo lakunja ladzala ndi mkuwa ndipo malo amkuwa atakhazikika (nthawi iliyonse 1/20 wavelength interval). Monga tafotokozera pamwambapa, mkuwa adzaikidwa


Nthawi yolembetsa: Jul-29-2020