Kuyilo lwe-PCB, ukuhambelana kwe-electromagnetic (EMC) kunye nokuphazamiseka kwe-electromagnetic ehambelanayo (EMI) ngokwesiko ibiziintloko ezimbini eziphambili kwiinjineli, ngakumbi kuyilo lwebhodi yesekethe yanamhlanje kunye neepakethi zamacandelo ziyaqhubeka nokuncipha, ii-OEMs zifuna iinkqubo zesantya esiphezulu.Kweli nqaku, ndiza kwabelana ngendlela yokuphepha iingxaki ze-electromagnetic kuyilo lwePCB.
1. I-Crosstalk kunye nokulungelelaniswa kugxininiso
Ukulungelelaniswa kubaluleke kakhulu ukuqinisekisa ukuhamba ngokufanelekileyo kwangoku.Ukuba i-current ivela kwi-oscillator okanye esinye isixhobo esifanayo, kubaluleke kakhulu ukugcina i-current ihluke kuluhlu lomhlaba, okanye ukugcina i-current isebenze ngokuhambelana nolunye ulungelelwaniso.Iimpawu ezimbini zesantya esiphezulu ngokuhambelana zinokuvelisa i-EMC kunye ne-EMI, ngakumbi i-crosstalk.Kubalulekile ukugcina iindlela zokuxhathisa zimfutshane ngokusemandleni kwaye iindlela zangoku zokubuya zibe zifutshane kangangoko.Ubude bendlela yokubuya kufuneka bulingane nobude bendlela yokuhambisa.
Kwi-EMI, enye indlela ibizwa ngokuba "yindlela yokwaphulwa" kwaye enye "yindlela yexhoba".I-inductive kunye ne-capacitive coupling ichaphazela indlela "yexhoba" ngenxa yobukho bemimandla ye-electromagnetic, ngaloo ndlela ivelisa phambili kunye nokubuyisela umva imisinga "kwindlela yexhoba".Ngale ndlela, i-ripple iveliswa kwindawo ezinzileyo apho ukuhambisa kunye nokufumana ubude bomqondiso kuphantse kulingane.
Kwimeko elungelelene kakuhle kunye nokulungelelaniswa okuzinzile, ii-currents ezibangelwayo kufuneka zikhansele ngaphandle, ngaloo ndlela ziphelise i-crosstalk.Noko ke, sikwihlabathi elingafezekanga ekungekho nto injalo.Ke ngoko, injongo yethu kukuba i-crosstalk kufuneka igcinwe incinci kulo lonke ulungelelwaniso.Umphumo we-crosstalk unokuncitshiswa ukuba ububanzi phakathi kwemigca ehambelanayo buphindwe kabini ububanzi bemigca.Umzekelo, ukuba ububanzi bomgca yi-5 mils, umgama omncinci phakathi kwemigca emibini ehambelanayo kufuneka ube yi-10 mils okanye ngaphezulu.
Njengoko izixhobo ezitsha kunye namacandelo eqhubeka ukubonakala, abayili bePCB kufuneka baqhubeke nokujongana ne-EMC kunye nemiba yokuphazamiseka.
2. Ukuqhawula ii-capacitors
I-Decoupling capacitors inciphisa imiphumo engathandekiyo ye-crosstalk.Kufuneka zibekwe phakathi kwamandla kunye nezikhonkwane zomhlaba zesixhobo, eziqinisekisa ukuba i-AC impedance ephantsi kunye nokunciphisa ingxolo kunye ne-crosstalk.Ukufezekisa i-impedance ephantsi kuluhlu olubanzi, ii-capacitors ezininzi zokuqhawula kufuneka zisetyenziswe.
Umgaqo obalulekileyo wokubeka i-decoupling capacitors kukuba i-capacitor enexabiso eliphantsi le-capacitance ibekwe ngokusondeleyo kwisixhobo ngokusemandleni ukunciphisa imiphumo ye-inductive kwi-alignments.Le capacitor ethile kufuneka ibekwe ngokusondeleyo kangangoko kunokwenzeka kwizikhonkwane zonikezelo lwamandla esixhobo okanye umbane wendlela yombane kunye neepads zecapacitor kufuneka ziqhagamshelwe ngokuthe ngqo kwi-vias okanye kwinqanaba lomhlaba.Ukuba ulungelelwaniso lude, sebenzisa ii-pass ezininzi ukunciphisa i-impedance yomhlaba.
3. Ukuthoba iPCB
Indlela ebalulekileyo yokunciphisa i-EMI kukuyila i-PCB yomgangatho wokumisa.Isinyathelo sokuqala kukwenza indawo yokumisa ibenkulu kangangoko ngaphakathi kwendawo epheleleyo yebhodi yePCB ukwenzela ukuba ukukhutshwa, i-crosstalk kunye nengxolo ingancitshiswa.Ukunyamekela ngokukodwa kufuneka kuthathwe xa udibanisa icandelo ngalinye kwindawo ephantsi komhlaba okanye umgangatho womhlaba, ngaphandle kokuba umphumo wokungathathi hlangothi womgangatho othembekileyo womhlaba awukwazi ukusetyenziswa ngokupheleleyo.
Uyilo oluntsonkothileyo lwePCB lunevoltheji ezininzi ezizinzileyo.Ngokufanelekileyo, i-voltage nganye yereferensi inomaleko wayo ohambelanayo.Nangona kunjalo, iileya ezininzi zokumisa zinganyusa iindleko zokwenziwa kwePCB kwaye ziyenze ibize kakhulu.Ulungelelaniso kukusebenzisa iileya ezisezantsi kwiindawo ezintathu ukuya kwezintlanu ezahlukeneyo, nganye kuzo inokuqulatha amacandelo amaninzi okumisa.Oku akulawuli kuphela iindleko zokwenziwa kwebhodi, kodwa kunciphisa i-EMI kunye ne-EMC.
Inkqubo yokumisa i-impedance ephantsi ibalulekile ukuba i-EMC iza kuncitshiswa.Kwi-PCB ye-multilayer kukhethwa ukuba ube ne-grounding layer ethembekileyo kunokuba ibhloko yebhalansi yobhedu (i-copper thieving) okanye i-grounding layering layering layer njengoko ine-impedance ephantsi, inika indlela yangoku kwaye ngowona mthombo weempawu ezibuyela umva.
Ubude bexesha elithathwa ngumqondiso ukubuyela emhlabeni nako kubaluleke kakhulu.Ixesha elithathiweyo ukuze umqondiso uhambe kunye nokusuka kumthombo kufuneka uthelekiseke, ngaphandle koko into efana ne-antenna iya kwenzeka, ivumela amandla ombane ukuba abe yinxalenye ye-EMI.Ngokufanayo, ukulungelelaniswa kwangoku ukuya / ukusuka kumthombo wesignali kufuneka kube mfutshane kangangoko kunokwenzeka, ukuba umthombo kunye neendlela zokubuya azikho ubude obulinganayo, ukuqhuma komhlaba kuya kwenzeka kwaye oku kuya kuvelisa i-EMI.
4. Gwema ii-angles ezingama-90
Ukunciphisa i-EMI, ulungelelwaniso, i-vias kunye namanye amacandelo kufuneka agwenywe ukwenza i-angle ye-90 °, kuba i-angle echanekileyo iya kuvelisa i-radiation.Ukuze ugweme i-angle ye-90 °, ukulungelelaniswa kufuneka kube ubuncinane ezimbini ze-angle ze-45 ° kwikona.
5. Ukusetyenziswa kwe-over-hole kufuneka uqaphele
Phantse kuzo zonke iiplagi zePCB, i-vias kufuneka isetyenziswe ukubonelela ngonxibelelwano lwe-conductive phakathi kweeleya ezahlukeneyo.Kwezinye iimeko, ziphinda zivelise ukubonakaliswa, njengoko i-impedance yeempawu zitshintsha xa i-vias idalwa ngolungelelwaniso.
Kwakhona kubalulekile ukukhumbula ukuba vias ukwandisa ubude ulungelelwaniso kwaye kufuneka itshatiswe.Kwimeko yolungelelwaniso lokwahluka, i-vias kufuneka iphetshwe apho kunokwenzeka.Ukuba le nto ayinakuphetshwa, i-vias kufuneka isetyenziswe kuzo zombini ulungelelwaniso ukuhlawulela ukulibaziseka kumqondiso kunye neendlela zokubuya.
6. Iintambo kunye nokukhusela ngokomzimba
Iintambo ezithwele iisekethe zedijithali kunye nemisinga ye-analogue inokuvelisa i-parasitic capacitance kunye ne-inductance, ebangela iingxaki ezininzi ezinxulumene ne-EMC.Ukuba iintambo eziphothiweyo zisetyenzisiwe, umgangatho ophantsi wokudibanisa ugcinwa kwaye imimandla yamagnetic eyenziwayo iyacinywa.Kwiimpawu zefrikhwensi ephezulu, iintambo ezikhuselekileyo kufuneka zisetyenziswe, zombini zibekwe phantsi ngaphambili nangasemva, ukuphelisa ukuphazamiseka kwe-EMI.
Ukukhusela ngokwasemzimbeni kukugquma yonke okanye inxalenye yenkqubo kwipakethe yentsimbi ukuthintela i-EMI ekungeneni kwisekethe yePCB.Olu khuselo lusebenza njenge-capacitor evaliweyo, eqhuba umhlaba, ukunciphisa ubungakanani be-antenna loop kunye nokufunxa i-EMI.
Ixesha lokuposa: Nov-23-2022