Ekwakhiweni kwe-PCB, ukuhambisana kwe-electromagnetic (EMC) kanye nokuphazanyiswa kwe-electromagnetic interference (EMI) ngokuvamile bekuyikhanda eliyinhloko lekhanda konjiniyela, ikakhulukazi emiklamo yanamuhla yebhodi lesifunda kanye namaphakheji ezingxenye ayaqhubeka nokuncipha, ama-OEM adinga amasistimu esivinini esikhulu.Kulesi sihloko, ngizokwabelana ngokuthi ungazigwema kanjani izinkinga ze-electromagnetic ekwakhiweni kwe-PCB.
1. I-Crosstalk nokuqondanisa yikona okugxilwe kukho
Ukuqondanisa kubaluleke kakhulu ukuze kuqinisekiswe ukugeleza okufanele kwamandla.Uma i-current ivela ku-oscillator noma enye idivayisi efanayo, kubaluleke kakhulu ukugcina okwamanje ihlukile kungqimba lomhlabathi, noma ukugcina yamanje ekusebenzeni ngokuhambisana nokunye ukuqondanisa.Amasignali amabili anesivinini esiphezulu ngokuhambisana angakhiqiza i-EMC ne-EMI, ikakhulukazi i-crosstalk.Kubalulekile ukugcina izindlela zokuphikisa zimfushane ngangokunokwenzeka futhi izindlela zamanje zokubuya zibe zifushane ngangokunokwenzeka.Ubude bendlela yokubuya kufanele bufane nobude bomzila wokudlulisa.
Ku-EMI, enye indlela ibizwa ngokuthi “indlela yokwephulwa” kanti enye “indlela yesisulu”.I-inductive ne-capacitive coupling ithinta indlela "yosisulu" ngenxa yobukhona bezinkambu ze-electromagnetic, ngaleyo ndlela ikhiqize imisinga eya phambili futhi ihlehlise "endleleni yesisulu".Ngale ndlela, i-ripple ikhiqizwa endaweni ezinzile lapho ubude bokudlulisa nokwamukela besignali bucishe bulingane.
Endaweni enokulinganisela kahle enokuqondanisa okuzinzile, imisinga ebangwayo kufanele ikhansele yodwa, ngaleyo ndlela isuse i-crosstalk.Nokho, siphila ezweni elingaphelele lapho into enjalo ingenzeki khona.Ngakho-ke, inhloso yethu ukuthi i-crosstalk kufanele igcinwe incane kukho konke ukuqondanisa.Umthelela we-crosstalk ungancishiswa uma ububanzi phakathi kwemigqa ehambisanayo buphindwe kabili ububanzi bemigqa.Isibonelo, uma ububanzi bomugqa bungama-mils angu-5, ibanga elincane phakathi kwemigqa emibili ehambisanayo kufanele libe ama-mils angu-10 noma ngaphezulu.
Njengoba izinto ezintsha nezingxenye ziqhubeka nokuvela, abaklami be-PCB kufanele futhi baqhubeke nokubhekana ne-EMC kanye nezinkinga zokuphazamiseka.
2. I-Decoupling capacitor
Ama-Decoupling capacitor anciphisa imiphumela engathandeki ye-crosstalk.Kufanele abekwe phakathi kwamandla nezikhonkwane zaphansi zedivayisi, okuqinisekisa ukuthi i-AC ibambezeleka iphansi futhi inciphisa umsindo ne-crosstalk.Ukuze uthole i-impedance ephansi phezu kwebanga elibanzi, ama-decoupling capacitor amaningi kufanele asetshenziswe.
Isimiso esibalulekile sokubeka ama-decoupling capacitor ukuthi i-capacitor enenani eliphansi kakhulu le-capacitance ibekwe eduze kwedivayisi ngangokunokwenzeka ukuze kuncishiswe imiphumela eguquguqukayo ekuqondeni.Le capacitor ethile kufanele ibekwe eduze kakhulu nezikhonkwane zokuphakela amandla edivayisini noma umzila wokuphakela amandla futhi amaphedi e-capacitor kufanele axhunywe ngokuqondile ku-vias noma ezingeni eliphansi.Uma ukuqondanisa kukude, sebenzisa izindlela eziningi ukuze unciphise ukuvinjelwa komhlaba.
3. Ukugawula i-PCB
Indlela ebalulekile yokunciphisa i-EMI ukuklama isendlalelo esiphansi se-PCB.Isinyathelo sokuqala siwukwenza indawo ephansi ibe nkulu ngangokunokwenzeka ngaphakathi kwendawo yonke yebhodi le-PCB ukuze kuncishiswe ukukhishwa, ukungqubuzana nomsindo.Kufanele kuqashelwe ngokukhethekile lapho kuxhunywa ingxenye ngayinye endaweni ephansi noma ungqimba oluphansi, ngaphandle kwalokho umphumela wokungathathi hlangothi wongqimba olunokwethenjelwa lwesisekelo awukwazi ukusetshenziswa ngokugcwele.
Idizayini eyinkimbinkimbi ye-PCB inama-voltage amaningana azinzile.Ngokufanelekile, i-voltage ngayinye yereferensi inesendlalelo sayo sokumisa esihambisanayo.Kodwa-ke, izendlalelo eziningi zokubeka phansi zingakhuphula izindleko zokukhiqiza ze-PCB futhi zenze ibize kakhulu.Isivumelwano siwukusebenzisa izendlalelo zaphansi ezindaweni ezintathu kuya kwezinhlanu ezihlukene, ngayinye yazo ingaba nezigaba ezimbalwa zokubeka phansi.Lokhu akulawuli kuphela izindleko zokukhiqiza zebhodi, kodwa futhi kunciphisa i-EMI ne-EMC.
Uhlelo oluphansi lwe-impedance grounding lubalulekile uma i-EMC izoncishiswa.Ku-PCB enezingqimba eziningi kungcono ukuthi kube nongqimba olunokwethenjelwa lwesisekelo kune-block yebhalansi yethusi (ukweba ithusi) noma ungqimba olusekelwe phansi oluhlakazekile njengoba lunokuvinjelwa okuphansi, luhlinzeka ngendlela yamanje futhi luwumthombo ongcono kakhulu wamasignali ahlehlayo.
Ubude besikhathi isignali esithathayo ukubuyela phansi nayo ibaluleke kakhulu.Isikhathi esithathwayo ukuze isiginali ihambe iye futhi isuke emthonjeni kufanele siqhathaniswe, ngaphandle kwalokho into efana ne-antenna izokwenzeka, okuvumela amandla okukhishwa kwemisebe ukuthi abe yingxenye ye-EMI.Ngokufanayo, ukuqondanisa kwamanje kuya/kusuka kumthombo wesignali kufanele kube kufushane ngangokunokwenzeka, uma umthombo nezindlela zokubuya zingenabo ubude obulinganayo, ukugxuma komhlaba kuzokwenzeka futhi lokhu kuzophinde kukhiqize i-EMI.
4. Gwema ama-engeli angu-90°
Ukuze kuncishiswe i-EMI, ukuqondanisa, i-vias nezinye izingxenye kufanele kugwenywe ukuze kwakhiwe i-engeli engu-90°, ngoba i-engeli elungile izokhiqiza imisebe.Ukuze ugweme i-angle engu-90 °, ukuqondanisa kufanele kube okungenani izintambo ezimbili ze-engeli engu-45 ° ekhoneni.
5. Ukusetshenziswa kwe-over-hole kudingeka uqaphele
Cishe kuzo zonke izakhiwo ze-PCB, i-vias kufanele isetshenziselwe ukuhlinzeka ngoxhumano lwe-conductive phakathi kwezendlalelo ezihlukene.Kwezinye izimo, ziphinde zikhiqize ukubonakaliswa, njengoba i-impedance yesici ishintsha lapho i-vias idalwa ekuqondaneni.
Kubalulekile futhi ukukhumbula ukuthi vias ukwandisa ubude ukuqondanisa futhi kudingeka ifaniswe.Endabeni yokuqondanisa okuhlukene, i-vias kufanele igwenywe lapho kungenzeka khona.Uma lokhu kungenakugwenywa, i-vias kufanele isetshenziswe kukho kokubili ukuqondanisa ukuze kunxeshezelwe ukubambezeleka kwesignali nezindlela zokubuya.
6. Amakhebula nokuzivikela ngokomzimba
Amakhebuli aphethe amasekhethi edijithali namaza e-analogue angakha amandla e-parasitic kanye ne-inductance, okubangela izinkinga eziningi ezihlobene ne-EMC.Uma kusetshenziswa izintambo ezimbili ezisontekile, izinga eliphansi lokuhlanganisa liyagcinwa futhi izinkambu kazibuthe ezikhiqizwayo ziyaqedwa.Kumasignali amafrikhwensi aphezulu, izintambo ezivikelwe kufanele zisetshenziswe, kukho kokubili isisekelo sazo nangemuva, ukuze kuqedwe ukuphazamiseka kwe-EMI.
Ukuvikela okungokoqobo ukumbozwa kwalo lonke noma ingxenye yesistimu kuphakheji yensimbi ukuvimbela i-EMI ukuthi ingangeni kumjikelezo we-PCB.Lokhu kuvikela kusebenza njenge-capacitor evaliwe, eqhuba phansi, yehlisa usayizi weluphu ye-antenna kanye ne-EMI emuncayo.
Isikhathi sokuthumela: Nov-23-2022