Uyisombulula njani ingxaki ye-EMI kuyilo lwePCB yeMultilayer?

Ngaba uyazi ukuba uyisombulula njani ingxaki ye-EMI xa uyilo lwePCB enamaleko amaninzi?

Makhe ndikuxelele!

Zininzi iindlela zokusombulula iingxaki ze-EMI.Iindlela zale mihla zocinezelo ze-EMI ziquka: ukusebenzisa i-EMI yokucinezela ukutyabeka, ukukhetha iindawo ezifanelekileyo zokucinezela kwe-EMI kunye noyilo lokulinganisa lwe-EMI.Ngokusekwe kolona yilo lwePCB olusisiseko, eli phepha lixoxa ngomsebenzi wesitaki sePCB ekulawuleni i-EMI radiation kunye nezakhono zoyilo lwePCB.

ibhasi yamandla

Ukutsiba kwamandla ombane we-IC kunokukhawuleziswa ngokubeka i-capacitance efanelekileyo kufutshane ne-pin yamandla ye-IC.Noko ke, oku akuphelelanga apho.Ngenxa yokuphendula okulinganiselweyo kwe-frequency ye-capacitor, akunakwenzeka ukuba i-capacitor ivelise amandla e-harmonic afunekayo ukuqhuba i-IC output ngokucocekileyo kwi-band frequency band.Ukongeza, i-voltage edlulayo eyenziwe kwibhasi yamandla iya kubangela ukuhla kwamandla ombane kuzo zombini iziphelo ze-inductance yendlela yokuqhawula.La mandla ombane adlulayo zezona mithombo zixhaphakileyo zokuphazamiseka kwe-EMI.Sinokuzicombulula njani ezi ngxaki?

Kwimeko ye-IC kwibhodi yethu yesiphaluka, i-power layer ejikeleze i-IC inokuthathwa njenge-high-frequency capacitor, enokuqokelela amandla avuzayo yi-discrete capacitor enika amandla aphezulu-frequency kwimveliso ecocekileyo.Ukongeza, i-inductance yomgangatho ofanelekileyo wamandla incinci, ngoko ke isiginali yethutyana eyenziwe yi-inductor nayo incinci, ngaloo ndlela inciphisa imo ye-EMI eqhelekileyo.

Ngokuqinisekileyo, uxhulumaniso phakathi koluhlu lonikezelo lwamandla kunye nephini lokunikezela umbane lwe-IC kufuneka lube lufutshane kangangoko kunokwenzeka, kuba umgca wokunyuka wesiginali yedijithali ukhawuleza kwaye ukhawuleza.Kungcono ukuyidibanisa ngokuthe ngqo kwi-pad apho i-pin yamandla ye-IC ikhona, ekufuneka ixoxwe ngokwahlukileyo.

Ukuze ulawule i-EMI yemowudi eqhelekileyo, umaleko wamandla kufuneka ube yiperi eyilwe kakuhle yomaleko wamandla ukuze uncede i-decouple kwaye ibe ne-inductance ephantsi ngokwaneleyo.Abanye abantu banokubuza, ingaba ilungile kangakanani?Impendulo ixhomekeke kumaleko wamandla, imathiriyeli phakathi kweeleya, kunye nesantya sokusebenza (oko kukuthi, umsebenzi wexesha lokunyuka kwe-IC).Ngokubanzi, isithuba somaleko wamandla yi-6mil, kunye ne-interlayer yi-FR4 material, ngoko ke i-capacitance elinganayo nge-intshi nganye yesikwere somgangatho wamandla malunga ne-75pF.Ngokucacileyo, isithuba esincinci somaleko, kokukhona sikhulu i-capacitance.

Akukho zixhobo ezininzi ezinexesha lokunyuka kwe-100-300ps, kodwa ngokwezinga lophuhliso lwangoku lwe-IC, izixhobo ezinexesha lokunyuka kwinqanaba le-100-300ps ziya kuthatha umlinganiselo ophezulu.Kwiisekethe ezinama-100 ukuya kuma-300 amaxesha okunyuka kwe-PS, isithuba se-3 mil layer asisasebenzi kwizicelo ezininzi.Ngelo xesha, kuyimfuneko ukwamkela iteknoloji ye-delamination kunye ne-interlayer spacing engaphantsi kwe-1mil, kwaye indawo ye-dielectric ye-FR4 yezinto eziphathekayo kunye ne-dielectric constant constant.Ngoku, ii-ceramics kunye neeplastiki ze-potted zinokuhlangabezana neemfuno zoyilo lwe-100 ukuya kwi-300ps yokunyuka kwexesha lokunyuka kweesekethe.

Nangona izinto ezintsha kunye neendlela zingasetyenziswa kwixesha elizayo, i-1 ukuya kwi-3 ns iisekhethi zexesha lokunyuka, i-3 ukuya kwi-6 mil isithuba se-layer spacing, kunye ne-FR4 izinto ze-dielectric zihlala zanele ukuphatha i-harmonics ephezulu kunye nokwenza izibonakaliso zexeshana zibe phantsi ngokwaneleyo, oko kukuthi. , imowudi eqhelekileyo EMI inokuncitshiswa kakhulu.Kweli phepha, umzekelo woyilo lwe-PCB yokupakishwa komgangatho unikwe, kwaye isithuba somaleko sithathwa njenge-3 ukuya kwi-6 mil.

i-electromagnetic shielding

Ukusuka kwindawo yokujonga umqondiso, isicwangciso esilungileyo sokubeka isicwangciso kufuneka sibe kukubeka zonke iimpawu zesignali kwindawo enye okanye ngaphezulu, esecaleni komgangatho wamandla okanye indiza yomhlaba.Ukunikezelwa kwamandla, isicwangciso esihle sokubeka i-layer kufuneka sibe ukuba umbane wamandla usondelene nendiza yomhlaba, kwaye umgama phakathi komgangatho wamandla kunye nendiza yomhlaba kufuneka ube yincinci kangangoko kunokwenzeka, into esiyibiza ngokuba "i-layer" isicwangciso.

PCB istaki

Loluphi uhlobo lwesicwangciso sokupakisha esinokunceda ukukhusela kunye nokucinezela i-EMI?Isikimu sokupakisha esicwangcisiweyo esilandelayo sithatha ukuba umbane wangoku uqukuqela kwinqanaba elinye kunye nokuba amandla ombane omnye okanye ii-voltages ezininzi zisasazwa kwiindawo ezahlukeneyo zomaleko ofanayo.Imeko yomaleko wamandla amaninzi iya kuxoxwa kamva.

I-4-ply plate

Kukho ezinye iingxaki ezinokubakho kuyilo lwe-4-ply laminates.Okokuqala, nokuba umaleko wesiginali ukwimaleko angaphandle kwaye amandla kunye nenqwelomoya yomhlaba zikumaleko angaphakathi, umgama phakathi komgangatho wamandla kunye nenqwelomoya yomhlaba usemkhulu kakhulu.

Ukuba imfuno yeendleko iyokuqala, iindlela ezimbini ezilandelayo kwibhodi ye-4-ply yendabuko inokuqwalaselwa.Bobabini banokuphucula ukusebenza koxinzelelo lwe-EMI, kodwa bafanelekile kuphela kwimeko apho ukuxinana kwamacandelo ebhodini kuphantsi ngokwaneleyo kwaye kukho indawo eyaneleyo ejikeleze amacandelo (ukubeka i-copper efunekayo yokubeka umbane).

Eyokuqala yinkqubo ekhethiweyo.Iimaleko zangaphandle zePCB zizo zonke iileya, kwaye imigangatho emibini ephakathi yimiqondiso / yamandla amandla.Unikezelo lwamandla kuluhlu lwesignali luhanjiswa ngemigca ebanzi, eyenza indlela yokuthintela ukunikezelwa kwamandla ngoku iphantsi kunye nokuphazamiseka kwendlela ye-signal ye-microstrip ephantsi.Ukusuka kwimbono yolawulo lwe-EMI, le yeyona nto ilungileyo ye-4-layer PCB ekhoyo.Kwiskimu sesibini, umaleko wangaphandle uphethe amandla kunye nomhlaba, kwaye umbindi ophakathi uthwala umqondiso.Xa kuthelekiswa nebhodi yendabuko ye-4-layer, ukuphuculwa kwesi sikimu sincinci, kwaye i-impedance ye-interlayer ayilunganga njengebhodi ye-4 yendabuko.

Ukuba i-impedance ye-wiring kufuneka ilawulwe, iskimu sokupakisha esingentla kufuneka silumke kakhulu ukubeka i-wiring phantsi kwesiqithi sobhedu sonikezelo lwamandla kunye nomhlaba.Ukongeza, isiqithi sobhedu kunikezelo lwamandla okanye i-stratum kufuneka sidityaniswe kangangoko kunokwenzeka ukuqinisekisa unxibelelwano phakathi kwe-DC kunye ne-frequency ephantsi.

I-6-ply plate

Ukuba ubuninzi bamacandelo kwibhodi ye-4-layer inkulu, i-plate ye-6-layer ingcono.Nangona kunjalo, umphumo wokukhusela wezinye izikimu zokupakisha kuyilo lwebhodi ye-6-layer ayilungile ngokwaneleyo, kwaye umqondiso wexeshana webhasi yamandla awuncitshiswa.Imizekelo emibini ixoxwa apha ngezantsi.

Kwimeko yokuqala, ukunikezelwa kwamandla kunye nomhlaba kufakwe kwinqanaba lesibini kunye nelesihlanu ngokulandelanayo.Ngenxa ye-impedance ephezulu yonikezelo lwamandla obhedu, akulunganga kakhulu ukulawula imo yemitha ye-EMI eqhelekileyo.Nangona kunjalo, ukusuka kwindawo yokujonga ulawulo lwe-impedance yesignali, le ndlela ichanekile kakhulu.

Kumzekelo wesibini, ukunikezelwa kwamandla kunye nomhlaba zibekwe kwinqanaba lesithathu kunye nesine ngokulandelelana.Olu luyilo lusombulula ingxaki ye-copper clad impedance yonikezelo lwamandla.Ngenxa yokusebenza kakubi kwe-electromagnetic shielding ye-maleko 1 kunye ne-6, imo ye-EMI yokwahlula iyenyuka.Ukuba inani lemigca yesignali kwimigangatho emibini yangaphandle incinci kwaye ubude bemigca bufutshane kakhulu (ngaphantsi kwe-1 / 20 ye-wavelength ephezulu ye-harmonic yesiginali), uyilo lunokusombulula ingxaki yendlela yokwahlula i-EMI.Iziphumo zibonisa ukuba ukucuthwa kwendlela yokwahlula i-EMI ilungile ngakumbi xa umaleko wangaphandle uzaliswe ngobhedu kwaye indawo enengubo yobhedu isekelwe (rhoqo i-1/20 ye-wavelength interval).Njengoko kukhankanyiwe ngasentla, ubhedu luya kubekwa


Ixesha lokuposa: Jul-29-2020