In Isantya esiphezulu sePCB uyilo, ukusetyenziswa komqondiso wokuhlukanisa (i-DIFferential Signal) iya ikhula ngakumbi kwaye ibanzi, kwaye uphawu olubaluleke kakhulu kwisekethe luhlala luyilwe kunye nesakhiwo esahlukileyo. Kutheni kunjalo nje? Xa kuthelekiswa nomzila wesignali onesiphelo esiqhelekileyo, imiqondiso eyahlukileyo ineengenelo zesakhono esinamandla sokuchasa ukuphazamiseka, ukucinezelwa okusebenzayo kwe-EMI, kunye nokubeka ixesha elichanekileyo.

Iimfuno zocingo zePCB zophawu olwahlukileyo

Kwibhodi yesekethe, ukulandelelana okungafaniyo kufuneka kube yimigca emibini yobude obulinganayo, ububanzi obulinganayo, ukusondela, kunye nomgangatho ofanayo.

1. Ubude obulinganayo: Ubude obulinganayo buthetha ukuba ubude bemigca emibini kufuneka bube bubude kangangoko, ukuze kuqinisekiswe ukuba iimpawu ezimbini zokwahluka zigcina iipolarities ezichaseneyo ngamaxesha onke. Nciphisa amacandelo emowudi eqhelekileyo.

2. Ububanzi obulinganayo kunye nomgama olinganayo: Ububanzi obulinganayo buthetha ukuba ububanzi bemikhondo yemiqondiso emibini kufuneka bugcinwe bufana, kwaye umgama olinganayo uthetha ukuba umgama phakathi kweengcingo ezimbini kufuneka ugcinwe ungatshintshi kwaye uhambelana.

3. Utshintsho oluncinci lwe-impedance: Xa uyila i-PCB eneempawu ezihlukeneyo, enye yezona zinto zibalulekileyo kukufumanisa i-impedance ekujoliswe kuyo yesicelo, kwaye emva koko ucwangcise izibini ezihlukeneyo ngokufanelekileyo. Ukongeza, gcina utshintsho lwe-impedance luncinci kangangoko kunokwenzeka. Ukuphazamiseka komgca wokwahlukana kuxhomekeke kwizinto ezifana nobubanzi bomkhondo, ukudibanisa umkhondo, ubukhulu bobhedu, kunye nezinto zePCB kunye ne-stackup. Xa uzama ukuphepha nayiphi na into eguqula i-impedance yesibini esahlukileyo, qwalasela nganye kuzo.

Ukungaqondani okuqhelekileyo kwi-PCB yoyilo lophawu lokwahlukana

Ukungaqondi kakuhle i-1: Kukholelwa ukuba isignali yokwahlukana ayifuni inqwelomoya ephantsi njengendlela yokubuya, okanye ukuba iindlela ezihlukeneyo zibonelela ngendlela yokubuyela komnye nomnye.

Isizathu salokhu kungaqondi kakuhle kukuba badideke ngeziganeko ezingaphezulu, okanye indlela yokuhanjiswa kwesignali yesantya esiphezulu ayinzulu ngokwaneleyo. Iisekethe ezihlukeneyo azikhathaleli kwii-bounces zomhlaba ezifanayo kunye nezinye iimpawu zengxolo ezinokuthi zibe khona kumandla kunye neenqwelomoya zomhlaba. Ukucinywa kokubuyiswa kwenxalenye yendiza yomhlaba akuthethi ukuba isiphaluka esahlukileyo asisebenzisi indiza yereferensi njengendlela yokubuyisela umqondiso. Enyanisweni, kuhlalutyo lokubuyisela umqondiso, indlela yokudibanisa i-wiring kunye ne-wiring eqhelekileyo i-single-end iyafana, oko kukuthi, izibonakaliso ze-high-frequency zihlala zi-Reflow kunye ne-loop kunye neyona inductance encinci. Umahluko omkhulu kukuba ngaphezu kokudibanisa emhlabathini, umgca wokuhlukana nawo unokubambisana. Luluphi uhlobo lokudibanisa olomeleleyo, kwaye yeyiphi eba yindlela ephambili yokubuyela.

Kuyilo lwesekethe ye-PCB, ukudityaniswa phakathi komkhondo wokwahlukana kuncinci, ngokufuthi kubalelwa kwi-10-20% yedigri yokudibanisa, kwaye ngaphezulu kukudityaniswa emhlabeni, ngoko ke eyona ndlela iphambili yokubuya komkhondo wokwahlukana isekhona emhlabeni. inqwelomoya . Xa kukho ukungaqhubeki kwinqwelo-moya yomhlaba, ukudibanisa phakathi kweempawu ezihlukeneyo kwindawo ngaphandle kwendiza yesalathiso kuya kunika indlela yokubuyela engundoqo, nangona ukupheliswa kwenqwelo-moya yokukhangela akunayo impembelelo kwiimpawu ezihlukeneyo kwisiqhelo esisodwa esiphelile. umkhondo Inzulu, kodwa iya kunciphisa umgangatho wesignali yokwahlukana kunye nokwandisa i-EMI, ekufuneka igwenywe kangangoko kunokwenzeka.

Ukongeza, abanye abaqulunqi bakholelwa ukuba inqwelomoya yereferensi phantsi komkhondo ohlukeneyo inokususwa ukucinezela inxalenye yesiginali yemowudi eqhelekileyo ekuhanjisweni okwahlukileyo. Nangona kunjalo, le ndlela ayinqweneleki kwithiyori. Indlela yokulawula i-impedance? Ukungaboneleli ngeluphu yothintelo lomhlaba kwisignali yendlela eqhelekileyo ngokuqinisekileyo kuya kubangela imitha ye-EMI. Le ndlela yenza umonakalo omkhulu kunokulunga.

Ukungaqondi kakuhle 2: Kukholelwa ukuba ukugcina izithuba ezilinganayo kubaluleke ngaphezu kobude bomgca wokutshatisa.

Kuyilo lwePCB olululo, kaninzi akunakwenzeka ukuhlangabezana neemfuno zoyilo lolwahlulo ngaxeshanye. Ngenxa yobukho bezinto ezifana nokusasazwa kwephini, i-vias, kunye nesithuba socingo, injongo yokumatanisa ubude bomgca kufuneka iphunyezwe ngokujija ngokufanelekileyo, kodwa isiphumo kufuneka sibe kukuba ezinye iindawo zesibini sokwahlukana azikwazi ukuhambelana. Owona mthetho ubalulekileyo kuyilo lwe-PCB yokwahlukana kweempawu ubude bomgca ohambelanayo. Eminye imithetho inokuphathwa ngokuguquguqukayo ngokweemfuno zoyilo kunye nezicelo zokwenyani.

Ukungaqondi kakuhle 3: Cinga ukuba i-wiring yokwahlukana kufuneka isondele kakhulu.

Ukugcina umkhondo wokwahlula ukufutshane akukho nto ingaphaya kokuphucula ukudityaniswa kwawo, okunokuthi kungaphuculi kuphela ukungakhuseleki kwingxolo, kodwa nokusebenzisa ngokupheleleyo i-polarity echasene nemagnethi ukuphelisa ukuphazamiseka kwe-electromagnetic kwihlabathi langaphandle. Nangona le ndlela inenzuzo kakhulu kwiimeko ezininzi, ayikho ngokupheleleyo. Ukuba sinokuqinisekisa ukuba zikhuseleke ngokupheleleyo ekuphazamisekeni kwangaphandle, ngoko akufuneki ukuba sisebenzise ukudibanisa okuqinileyo ukufezekisa ukuchasana nokuphazamiseka. Kwaye injongo yokucinezela i-EMI.

Singenza njani ukuze siqinisekise ukwahlukaniswa okufanelekileyo kunye nokukhuselwa kwemikhondo eyahlukileyo? Ukwandisa izithuba kunye nezinye iimpawu zesignali yenye yezona ndlela zisisiseko. I-electromagnetic field energy iyancipha ngesikwere somgama. Ngokuqhelekileyo, xa isithuba somgca sidlula amaxesha ama-4 ububanzi bomgca, ukuphazamiseka phakathi kwabo kubuthathaka kakhulu. Inokungahoywa.