Kuyilo lwe-PCB, ukuhambelana kwe-electromagnetic (EMC) kunye nokuphazamiseka kwe-electromagnetic ehambelanayo (EMI) bezisoloko ziyingxaki ezimbini ezinkulu eziye zabangela ukuba iinjineli zibe nentloko ebuhlungu, ngakumbi kuyilo lwebhodi yesekethe yanamhlanje kunye nokupakishwa kwecandelo kuyacutheka, kwaye ii-OEM zifuna iinkqubo zesantya esiphezulu.
1. I-Crosstalk kunye ne-wiring ngamanqaku aphambili
I-wiring ibaluleke kakhulu ukuqinisekisa ukuhamba okuqhelekileyo kwangoku. Ukuba i-current ivela kwi-oscillator okanye esinye isixhobo esifanayo, kubaluleke kakhulu ukugcina i-current ihluke kwi-plane yomhlaba, okanye ungavumeli ukuba i-current isebenze ngokuhambelana nomnye umkhondo. Iimpawu ezimbini ezihambelanayo ezinesantya esiphezulu ziya kuvelisa i-EMC kunye ne-EMI, ngakumbi i-crosstalk. Umendo wokuchasa kufuneka ube ngowona mfutshane, kwaye indlela yangoku yokubuya kufuneka ibe mfutshane kangangoko. Ubude bomzila womzila wokubuyela kufuneka bulingane nobude bokuthumela umkhondo.
Kwi-EMI, enye ibizwa ngokuba "yi-infringed wiring" kwaye enye "yi-victimized wiring". Ukudityaniswa kwe-inductance kunye ne-capacitance kuya kuchaphazela umkhondo "wexhoba" ngenxa yobukho bemimandla ye-electromagnetic, ngaloo ndlela ivelisa phambili kunye nokubuyisela umva imisinga "kwi-victim trace". Kule meko, i-ripples iya kuveliswa kwindawo ezinzileyo apho ubude bokuhambisa kunye nobude bokufumana uphawu buphantse bulingane.
Kwindawo elungelelanisiweyo kwaye izinzile i-wiring, i-currents induced kufuneka ikhansele omnye komnye ukuphelisa i-crosstalk. Noko ke, siphila kwihlabathi elingafezekanga, yaye izinto ezinjalo aziyi kwenzeka. Ke ngoko, injongo yethu kukugcina i-crosstalk yazo zonke iitrayisi zibencinci. Ukuba ububanzi phakathi kwemigca ehambelanayo buphindwe kabini ububanzi bemigca, umphumo we-crosstalk unokuncitshiswa. Umzekelo, ukuba ububanzi bomkhondo yi-5 mils, umgama omncinci phakathi kweetrayidi ezimbini ezihambelanayo kufuneka ube yi-10 mils okanye ngaphezulu.
Njengoko imathiriyeli emitsha kunye namacandelo amatsha eqhubeka nokuvela, abayili bePCB kufuneka baqhubeke nokujongana nokuhambelana kombane kunye nemiba yokuphazamiseka.
2. Ukuqhawula i-capacitor
I-Decoupling capacitors inokunciphisa imiphumo emibi ye-crosstalk. Kufuneka zibekwe phakathi kwepini yonikezelo lwamandla kunye nepini yomhlaba yesixhobo ukuze kuqinisekiswe i-impedance ephantsi ye-AC 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 elincinci le-capacitance kufuneka isondele kangangoko kunokwenzeka kwisixhobo sokunciphisa umphumo we-inductance kumkhondo. Le capacitor ethile isondele kangangoko kwiphini yamandla okanye umkhondo wamandla wesixhobo, kwaye udibanise i-pad ye-capacitor ngokuthe ngqo kwi-via okanye indiza yomhlaba. Ukuba umkhondo mde, sebenzisa iindlela ezininzi zokunciphisa uthintelo lomhlaba.
3. Gqiba iPCB
Indlela ebalulekileyo yokunciphisa i-EMI kukuyila inqwelomoya ephantsi ye-PCB. Inyathelo lokuqala kukwenza indawo yokumisa ibenkulu kangangoko ngaphakathi kwendawo yonke yebhodi yesekethe yePCB, enokunciphisa ukukhutshwa, ukungqubana kunye nengxolo. Ukunyamekela okukhethekileyo kufuneka kuthathwe xa udibanisa icandelo ngalinye kwindawo ephantsi okanye kwinqwelomoya. Ukuba oku akwenziwanga, umphumo wokungathathi hlangothi wendiza ethembekileyo yomhlaba awuyi kusetyenziswa ngokupheleleyo.
Uyilo oluntsonkothileyo lwePCB lunevoltheji ezininzi ezizinzileyo. Ngokufanelekileyo, i-voltage nganye yereferensi inendiza yayo ehambelana nayo. Nangona kunjalo, ukuba umaleko womhlaba mkhulu kakhulu, uya kwandisa iindleko zokwenziwa kwePCB kwaye wenze ixabiso libe phezulu kakhulu. I-compromise kukusebenzisa iinqwelomoya eziphantsi kwiindawo ezintathu ukuya kwezintlanu ezahlukeneyo, kwaye inqwelomoya nganye yomhlaba inokuba neendawo ezininzi zomhlaba. Oku akulawuli kuphela iindleko zokwenziwa kwebhodi yesekethe, kodwa kunciphisa i-EMI kunye ne-EMC.
Ukuba ufuna ukunciphisa i-EMC, inkqubo ye-impedance ephantsi ibaluleke kakhulu. Kwi-PCB enamanqwanqwa amaninzi, kungcono ukuba ube nenqwelo-moya ethembekileyo, kunokuba i-copper thieving okanye i-plane ehlakazekileyo yomhlaba, kuba ine-impedance ephantsi, inokubonelela ngendlela yangoku, eyona nto ingcono yomthombo wesignali ye-reverse.
Ubude bexesha umqondiso ubuyela emhlabeni nako kubaluleke kakhulu. Ixesha phakathi kwesiginali kunye nomthombo wesiginali kufuneka lilingane, ngaphandle koko liya kuvelisa into efana ne-antenna, okwenza amandla asasazwe abe yinxalenye ye-EMI. Ngokufanayo, umkhondo ohambisa okwangoku ukuya / ukusuka kumthombo wesignali kufuneka ube mfutshane kangangoko. Ukuba ubude bendlela yomthombo kunye nendlela yokubuya ayilingani, ukutsiba komhlaba kuya kwenzeka, okuya kuvelisa i-EMI.
4. Gwema i-angle ye-90 °
Ukuze kuncitshiswe i-EMI, gwema i-wiring, i-vias kunye nezinye izinto ezenza i-angle ye-90 °, kuba ii-angles ezifanelekileyo ziza kuvelisa i-radiation. Kule kona, i-capacitance iya kwanda, kwaye i-impedance yeempawu nayo iya kutshintsha, ikhokelela ekubonakalisweni kunye ne-EMI. Ukuphepha ii-angles ezingama-90 °, umkhondo kufuneka uhanjiswe kwiikona ubuncinane kwii-engile ezingama-45 ° ezimbini.
5. Sebenzisa ngokuqaphela
Phantse kuzo zonke iiplagi zePCB, i-vias kufuneka isetyenziswe ukubonelela ngemidibaniso eqhubayo phakathi kweeleya ezahlukeneyo. Iinjineli zoyilo lwe-PCB kufuneka zilumke ngakumbi kuba i-vias iya kuvelisa i-inductance kunye ne-capacitance. Kwezinye iimeko, ziya kuvelisa imiboniso, kuba i-impedance yeempawu iya kutshintsha xa i-via yenziwa kumkhondo.
Kwakhona khumbula ukuba i-vias iya kwandisa ubude bomkhondo kwaye kufuneka ihambelane. Ukuba ngumkhondo owahlukileyo, i-vias kufuneka ithintelwe kangangoko kunokwenzeka. Ukuba ayinakuphetshwa, sebenzisa i-vias kuzo zombini iitrayisi ukubuyisela ukulibaziseka kwisignali kunye nendlela yokubuya.
6. Ikhebula kunye nokukhusela ngokomzimba
Iintambo eziphethe iisekethe zedijithali kunye nemisinga ye-analog ziya kuvelisa i-parasitic capacitance kunye ne-inductance, ebangela iingxaki ezininzi ezinxulumene ne-EMC. Ukuba intambo ephothiweyo isetyenzisiwe, umgangatho wokudibanisa uya kugcinwa uphantsi kwaye i-magnetic field eyenziwe iya kupheliswa. Kwiimpawu ze-high-frequency, intambo ekhuselekileyo kufuneka isetyenziswe, kwaye i-front and back of cable kufuneka ibekwe phantsi ukuphelisa ukuphazamiseka kwe-EMI.
Ukukhusela ngokwasemzimbeni kukusonga yonke okanye inxalenye yenkqubo ngepakethe yentsimbi ukuthintela i-EMI ekungeneni kwisekethe yePCB. Olu hlobo lokhuselo lufana nesikhongozeli se-conductive esivaliweyo, esinciphisa ubungakanani be-antenna loop kwaye ifunxa i-EMI.