Ngaphezu kokukhethwa kwezingxenye kanye nomklamo wesifunda, kuhle ibhodi yesifunda ephrintiwe (PCB) ukwakheka nakho kuyisici esibaluleke kakhulu ekusebenzisaneni kwe-electromagnetic. Ukhiye wokuklama kwe-PCB EMC ukunciphisa indawo yokugeleza kabusha ngangokunokwenzeka futhi uvumele indlela yokugeleza igeleze ibheke lapho kuklanywe khona. Izinkinga zamanje ezibuyayo ezivame kakhulu zivela emifantwini endizeni yereferensi, ukushintsha ungqimba lwendiza eyinkomba, nesignali egeleza kusixhumi. Ama-jumper capacitor noma ama-decoupling capacitor angase axazulule izinkinga ezithile, kodwa ukuvinjelwa okuphelele kwama-capacitor, ama-vias, ama-pads, nezintambo kufanele kucatshangelwe. Lesi sifundo sizokwethula ubuchwepheshe bokuklama be-PCB be-EMC obuvela ezicini ezintathu: isu le-PCB elendlalelo, amakhono esakhiwo kanye nemithetho yezintambo.

Isu lesendlalelo se-PCB

Ugqinsi, ngenqubo kanye nenani lezendlalelo ekwakhiweni kwebhodi lesifunda akusona isihluthulelo sokuxazulula inkinga. Ukunqwabelanisa okuhle kwezendlalelo ukuqinisekisa ukudlula nokuqaqa ibhasi lamandla futhi unciphise i-voltage yesikhashana esendlalelo samandla noma ungqimba lomhlabathi. Ukhiye wokuvikela inkambu ye-electromagnetic yesiginali kanye nokunikezwa kwamandla. Ngokombono wokulandela isignali, isu elihle lokubeka izingqimba kufanele kube ukubeka yonke imikhondo yesignali kungqimba eyodwa noma eziningana, futhi lezi zendlalelo ziseduze nongqimba lwamandla noma ungqimba lomhlabathi. Ngokunikezwa kwamandla, isu elihle lokubeka izingqimba kufanele kube ukuthi ungqimba lwamandla luseduze nongqimba lomhlabathi, futhi ibanga phakathi kongqimba lwamandla kanye nongqimba lomhlabathi lincane ngangokunokwenzeka. Yilokhu esikubiza ngesu “lokwendlalela”. Ngezansi sizokhuluma ngokuqondile ngesu elihle kakhulu lokubeka izingqimba le-PCB. 1. Indiza yokuqagela yesendlalelo sezintambo kufanele ibe sendaweni yesendlalelo sendiza egeleza kabusha. Uma ungqimba lwezintambo lungekho endaweni yokuqagela yongqimba lwendiza egeleza kabusha, kuzoba nemigqa yesignali ngaphandle kwendawo yokuqagela ngesikhathi sokufaka izintambo, okuzodala inkinga “yemisebe yonqenqema”, futhi kuzophinde kubangele ukuthi indawo yesiginali ikhule. , okuholela ekwandeni kwemisebe yemodi ehlukile . 2. Zama ukugwema ukusetha izendlalelo zezintambo eziseduze. Ngenxa yokuthi ukulandelelwa kwesignali ehambisanayo kwezendlalelo zezintambo eziseduze kungabangela i-crosstalk yesignali, uma kungenakwenzeka ukugwema izendlalelo zezintambo eziseduze, isikhala sesendlalelo phakathi kwezingqimba ezimbili zezintambo kufanele sinyuswe ngendlela efanele, futhi isikhala sesendlalelo phakathi kwesendlalelo sezintambo kanye nesekhethi yesiginali kufanele senziwe. kuncishiswe. 3. Izendlalelo zendiza ezincikene kufanele zigweme ukugqagqana kwezindiza zazo. Ngoba uma ama-projection egqagqene, amandla okuhlanganisa phakathi kwezendlalelo azobangela umsindo phakathi kwezendlalelo ukuthi umbhangqene.

I-Multilayer board design

Uma imvamisa yewashi idlula u-5MHz, noma isikhathi sokukhuphuka kwesignali singaphansi kwama-5ns, ukuze ulawule indawo yeluphu yesiginali kahle, umklamo webhodi lezendlalelo eziningi ngokuvamile uyadingeka. Izimiso ezilandelayo kufanele zinakwe lapho uklama amabhodi ezendlalelo eziningi: 1. Isendlalelo sezintambo eziyisihluthulelo (isendlalelo lapho ulayini wewashi, ulayini webhasi, ulayini wesiginali yokuxhumana, ulayini wefrikhwensi yomsakazo, setha kabusha umugqa wesiginali, umugqa wesignali wokukhetha i-chip kanye nesiginali yokulawula ehlukahlukene. imigqa ikhona) kufanele ibe eduze nendiza yaphansi ephelele, okungcono kakhulu phakathi kwezindiza ezimbili eziphansi, njengalokhu Kuboniswe Emfanekisweni 1. Imigqa yesignali eyinhloko ngokuvamile imisebe enamandla noma imigqa yesignali ezwela kakhulu. Izintambo eziseduze nendiza yaphansi zinganciphisa indawo yeluphu yesiginali, zinciphise ukushuba kwemisebe noma zithuthukise ikhono lokulwa nokuphazamiseka.

Umfanekiso 1 Isendlalelo sezintambo eziyinhloko siphakathi kwezindiza ezimbili eziphansi

2. Indiza yamandla kufanele ihoxiswe ngokuqhathaniswa nendiza yayo yaphansi eseduze (inani elinconyiwe 5H～20H). Ukuhlehla kwendiza yamandla ngokuhlobene nendiza yayo ebuyayo kungacindezela ngempumelelo inkinga “yemisebe enqenqemeni”.

Ngaphezu kwalokho, indiza yamandla esebenzayo eyinhloko yebhodi (indiza yamandla esetshenziswa kakhulu) kufanele ibe seduze nendiza yayo ephansi ukuze kuncishiswe ngempumelelo indawo eyiluphu yamanje yokunikezwa kwamandla, njengoba kuboniswe kuMfanekiso 3.

Umfanekiso 3 Indiza yamandla kufanele ibe seduze nendiza yayo ephansi

3. Ukuthi awukho yini umugqa wesiginali ≥50MHz OKUPHEZULU kanye nezandlalelo zebhodi. Uma kunjalo, kungcono kakhulu ukuhamba isignali yefrikhwensi ephezulu phakathi kwezingqimba ezimbili zendiza ukuze ucindezele imisebe yayo emkhathini.

Ibhodi elinongqimba olulodwa kanye nomklamo webhodi onezingqimba ezimbili

Ngokuklanywa kwamabhodi ongqimba olulodwa kanye nongqimba oluphindwe kabili, ukuklanywa kwemigqa yesignali ebalulekile nemigqa yamandla kufanele kunakwe. Kumelwe kube nentambo ephansi eduze futhi ehambisana nokulandela amandla ukuze kwehliswe indawo yeluphu yamanje yamandla. “I-Guide Ground Line” kufanele ibekwe ezinhlangothini zombili zomugqa wesiginali eyisihluthulelo sebhodi longqimba olulodwa, njengoba kuboniswe kuMfanekiso 4. Indiza yomugqa wesiginali ebalulekile yebhodi elinezingqimba ezimbili kufanele ibe nendawo enkulu yomhlabathi. , noma indlela efanayo nebhodi lesendlalelo esisodwa, dweba “Ulayini Waphansi Womhlahlandlela”, njengoba kuboniswe kuMfanekiso 5. “Intambo ephansi yokuqapha” ezinhlangothini zombili zomugqa wesiginali oyinhloko inganciphisa indawo ye-loop yesignali ngakolunye uhlangothi, futhi iphinde igweme ukukhuluma phakathi komugqa wesiginali neminye imigqa yesiginali.

Ngokuvamile, ukubekwa kwebhodi le-PCB kungaklanywa ngokwethebula elilandelayo.

Amakhono wesakhiwo se-PCB

Lapho uklama isakhiwo se-PCB, thobela ngokugcwele isimiso sokuklama sokubeka umugqa oqondile eduze kwendlela yokugeleza kwesignali, futhi uzame ukugwema ukuzungeza emuva naphambili, njengoba kuboniswe kuMfanekiso 6. Lokhu kungagwema ukuhlanganisa isignali okuqondile futhi kuthinte ikhwalithi yesignali. Ukwengeza, ukuze kuvinjwe ukugxambukela kanye nokuhlangana phakathi kwamasekhethi nezingxenye ze-elekthronikhi, ukubekwa kwamasekhethi kanye nokuhlelwa kwezingxenye kufanele kulandele izimiso ezilandelayo:

1. Uma isikhombimsebenzisi “somhlabathi ohlanzekile” siklanyelwe ebhodini, izingxenye zokuhlunga nokuhlukanisa kufanele zibekwe ebhandeni lokuhlukanisa phakathi “kwenhlabathi ehlanzekile” nendawo yokusebenza. Lokhu kungavimbela izisetshenziswa zokuhlunga noma zokuzihlukanisa ukuthi zingahlangani ngesendlalelo seplana, esenza umphumela ube buthaka. Ngaphezu kwalokho, “emhlabathini ohlanzekile”, ngaphandle kwemishini yokuhlunga nokuvikela, awekho amanye amadivaysi angafakwa. 2. Uma amasekhethi amamojula amaningi ebekwe ku-PCB efanayo, amasekhethi edijithali namasekhethi e-analog, namasekhethi anesivinini esikhulu nanejubane eliphansi kufanele abekwe ngokwehlukana ukuze kugwenywe ukuphazamiseka phakathi kwamasekhethi edijithali, amasekhethi e-analog, amasekhethi anesivinini esikhulu, kanye izifunda ezinejubane eliphansi. Ukwengeza, lapho amasekhethi aphezulu, aphakathi nendawo, kanye nesivinini esiphansi ekhona ebhodini lesifunda ngesikhathi esifanayo, ukuze kuvinjwe umsindo wesekethe we-high-frequency kusukela ekuphumeni ngaphandle ngokusebenzisa isixhumi esibonakalayo.

3. Isekhethi yesihlungi sembobo yokufaka amandla yebhodi lesifunda kufanele ibekwe eduze kwesixhumi esibonakalayo ukuze kuvinjelwe isekethe ehlungiwe ukuthi ingahlanganiswa futhi.

Umfanekiso 8 Isekhethi yesihlungi sembobo yokufaka amandla kufanele ibekwe eduze kwesixhumi esibonakalayo

4. Izingxenye zokuhlunga, ukuvikelwa kanye nokuhlukaniswa kwesifunda se-interface zibekwe eduze kwesixhumi esibonakalayo, njengoba kuboniswe kuMfanekiso 9, ongafinyelela ngempumelelo imiphumela yokuvikela, ukuhlunga kanye nokuzihlukanisa. Uma kukhona kokubili okokuhlunga kanye nesekhethi yokuvikela kusixhumi esibonakalayo, umgomo wokuvikela kuqala bese ukuhlunga kufanele kulandelwe. Ngenxa yokuthi umjikelezo wokuvikela usetshenziselwa ukuqhuma kwangaphandle nokucindezela okungaphezu kwamandla, uma isifunda sokuvikela sibekwe ngemva komjikelezo wesihlungi, umjikelezo wesihlungi uzolimala ngokugcwala ngokweqile nokudlulela. Ngaphezu kwalokho, njengoba imigqa yokufaka neyokukhiphayo yesekethe izonciphisa ukuhlunga, ukuhlukaniswa noma umphumela wokuvikela lapho ihlanganiswa nomunye nomunye, qinisekisa ukuthi imigqa yokufaka neyokukhiphayo yesekethe yesihlungi (isihlungi), isifunda sokuzihlukanisa nokuvikela asikwenzi. mbhangqwana nomunye ngesikhathi sokuhlela.

5. Amasekhethi azwelayo noma amathuluzi (njengamasekhethi okusetha kabusha, njll.) kufanele abe kude okungenani ne-1000 mil ukusuka kunqenqema ngalunye lwebhodi, ikakhulukazi unqenqema lwesixhumi esibonakalayo sebhodi.

6. Ukugcinwa kwamandla kanye nama-capacitor okuhlunga ama-high-frequency filter kufanele abekwe eduze kwamasekhethi amayunithi noma amadivayisi anezinguquko ezinkulu zamanje (njengamatheminali okokufaka nokuphumayo emojula yamandla, amafeni, nama-relay) ukuze kuncishiswe indawo eyiluphu iluphu enkulu yamanje.

7. Izingxenye zokuhlunga kufanele zibekwe eceleni ukuze kuvinjelwe isifunda esihlungiwe ukuthi singaphazanyiswa futhi.

8. Gcina amadivaysi emisebe aqinile njengamakristalu, ama-crystal oscillator, ama-relay, kanye nokushintsha izinto zamandla okungenani amamitha ayi-1000 kude nezixhumi zebhodi. Ngale ndlela, ukuphazamiseka kungasakazwa ngokuqondile noma okwamanje kungahlanganiswa nekhebuli ephumayo ukuze kukhanye ngaphandle.

Imithetho yezintambo ze-PCB

Ngaphezu kokukhethwa kwezingxenye kanye nomklamo wesekethe, izintambo ezinhle zebhodi lesifunda eliphrintiwe (PCB) nazo ziyisici esibaluleke kakhulu ekusebenzisaneni kwe-electromagnetic. Njengoba i-PCB iyingxenye yemvelo yohlelo, ukuthuthukisa ukuhambisana kwe-electromagnetic kuzintambo ze-PCB ngeke kulethe izindleko ezengeziwe ekuqedeni kokugcina komkhiqizo. Noma ubani kufanele akhumbule ukuthi isakhiwo se-PCB esingesihle singabangela izinkinga eziningi zokuhambisana nogesi, kunokuziqeda. Ezimweni eziningi, ngisho nokwengezwa kwezihlungi nezingxenye akukwazi ukuxazulula lezi zinkinga. Ekugcineni, lonke ibhodi kwadingeka lifakwe izintambo kabusha. Ngakho-ke, kuyindlela engabizi kakhulu yokuthuthukisa imikhuba emihle yezintambo ze-PCB ekuqaleni. Okulandelayo kuzokwethula imithetho ejwayelekile yezintambo ze-PCB kanye namasu okuklama izintambo zikagesi, izintambo eziphansi kanye nemigqa yamasignali. Okokugcina, ngokwale mithetho, izinyathelo zokuthuthukisa zihlongozwa umjikelezo webhodi lesifunda eliphrintiwe le-air conditioner. 1. Ukuhlukaniswa kwezintambo Umsebenzi wokuhlukanisa izintambo ukunciphisa ukuhlangana kwe-crosstalk nomsindo phakathi kwamasekhethi aseduze kungqimba olufanayo lwe-PCB. Ukucaciswa kwe-3W kuthi wonke amasiginali (iwashi, ividiyo, umsindo, ukusetha kabusha, njll.) kufanele ahlukaniswe ukusuka kulayini kuye emgqeni, emaphethelweni kuye konqenqema, njengoba kuboniswe kuMfanekiso 10. Ukuze kuncishiswe ngokwengeziwe ukuhlangana kazibuthe, indawo yereferensi ibekwe eduze kwesiginali yokhiye ukuhlukanisa umsindo wokuhlanganisa okhiqizwa ezinye imigqa yesignali.

2. Ukuvikelwa kanye nesethingi ye-shunt line I-Shunt kanye nolayini wokuvikela kuyindlela ephumelela kakhulu yokuhlukanisa nokuvikela amasignali abalulekile, njengamasiginali wewashi lesistimu endaweni enomsindo. Emfanekisweni 21, isifunda esihambisanayo noma sokuvikela ku-PCB sibekwe eceleni kwesiginali yokhiye. Isekhethi yokuvikela ayihlukanisi nje kuphela i-coupling magnetic flux ekhiqizwa eminye imigqa yesignali, kodwa futhi ihlukanisa amasignali abalulekile ekuhlanganeni neminye imigqa yesignali. Umehluko phakathi komugqa we-shunt kanye nolayini wokuvikela ukuthi ulayini we-shunt akudingeki ukuba unqanyulwe (uxhunywe emhlabathini), kodwa zombili iziphetho zomugqa wokuvikela kufanele zixhunywe phansi. Ukuze kuqhutshekwe nokunciphisa ukuhlanganisa, isifunda sokuvikela ku-PCB yezendlalelo eziningi singangezwa ngendlela eya phansi kuzo zonke ezinye izingxenye.

3. Umklamo wolayini wamandla usekelwe kusayizi webhodi lesifunda eliphrintiwe lamanje, futhi ububanzi bomugqa wamandla bukhulu ngangokunokwenzeka ukuze kuncishiswe ukumelana ne-loop. Ngesikhathi esifanayo, yenza isiqondiso solayini wamandla kanye nentambo yaphansi ihambisane nesiqondiso sokudluliswa kwedatha, okusiza ukuthuthukisa ikhono lokulwa nomsindo. Kuphaneli eyodwa noma kabili, uma intambo yamandla iyinde kakhulu, i-decoupling capacitor kufanele yengezwe phansi njalo nge-3000 mil, futhi inani le-capacitor ngu-10uF+1000pF.

Idizayini yocingo oluphansi

Izimiso zokwakhiwa kwensimbi yomhlabathi yilezi:

(1) Umhlabathi wedijithali uhlukaniswe nomhlabathi we-analog. Uma kukhona kokubili ama-logic circuits nama-linear circuits ebhodini lesifunda, kufanele ahlukaniswe ngangokunokwenzeka. Umhlabathi wesifunda se-low-frequency kufanele usekelwe ngokuhambisana endaweni eyodwa ngangokunokwenzeka. Uma izintambo zangempela zinzima, zingaxhunywa kancane ochungechungeni bese zisekelwe ngokuhambisana. Isekhethi ye-high-frequency kufanele isekelwe ezindaweni eziningi ochungechungeni, ucingo oluphansi kufanele lube lufushane futhi luqashiswe, futhi i-foil yomhlaba efana negridi kufanele isetshenziswe eduze kwengxenye yefrikhwensi ephezulu ngangokunokwenzeka.

(2) Intambo yaphansi kufanele ibe wugqinsi ngangokunokwenzeka. Uma intambo yaphansi isebenzisa ulayini obambene kakhulu, amandla aphansi ashintsha ngokushintsha kwamandla, okunciphisa ukusebenza kokulwa nomsindo. Ngakho-ke, ucingo oluphansi kufanele luqiniswe ukuze ludlule izikhathi ezintathu zamanje ezivumelekile ebhodini eliphrintiwe. Uma kungenzeka, intambo yaphansi kufanele ibe ngu-2~3mm noma ngaphezulu.

(3) Intambo yaphansi yenza iluphu evaliwe. Kumabhodi aphrintiwe akhiwe kuphela amasekhethi edijithali, iningi lamasekethe awo aphansi ahlelwa ngamalophu ukuze kuthuthukiswe ukumelana nomsindo.

Idizayini yomugqa wesiginali

Ngemigqa yesignali eyisihluthulelo, uma ibhodi linongqimba lwezintambo zesignali yangaphakathi, imigqa yesignali yokhiye efana namawashi kufanele ibekwe kungqimba lwangaphakathi, futhi okubaluleke kakhulu kunikezwa ungqimba lwezintambo olukhethwayo. Ngaphezu kwalokho, imigqa yesignali ebalulekile akufanele idluliselwe endaweni yokwahlukanisa, okuhlanganisa izikhala zendiza eyinkomba ezibangelwa ama-vias namaphedi, ngaphandle kwalokho kuzoholela ekwandeni kwendawo yeluphu yesiginali. Futhi umugqa wesiginali obalulekile kufanele ube ngaphezu kuka-3H ukusuka onqenqemeni lwendiza yereferensi (H ukuphakama komugqa osuka endizeni eyireferensi) ukuze ucindezele umphumela wemisebe onqenqemeni. Olayini wewashi, olayini bamabhasi, olayini befrikhwensi yomsakazo kanye neminye imigqa yesiginali yeradiation enamandla kanye nokusetha kabusha imigqa yamasignali, imigqa yesignali yokukhetha i-chip, amasignali okulawula uhlelo neminye imigqa yamasignali ebucayi, ibenza baqhelelane nesixhumi esibonakalayo nemigqa yamasignali ephumayo. Lokhu kuvimbela ukuphazamiseka kolayini wesignali ekhazimulayo oqinile ukuthi ungahlangani nolayini wesignali ophumayo futhi uphume ngaphandle; futhi futhi igwema ukuphazamiseka kwangaphandle okulethwe ulayini wesiginali ephumayo ekuxhumaneni kuya kumugqa wesignali obucayi, okubangela ukuphazamiseka kwesistimu. Imigqa yesignali ehlukile kufanele ibe isendlalelo esifanayo, ubude obulinganayo, futhi isebenze ngokuhambisana, igcine i-impedance ingaguquki, futhi akumele kube khona enye izintambo phakathi kwemigqa yokuhlukanisa. Ngenxa yokuthi i-impedance yemodi evamile yokubhanqwa komugqa wokuhlukanisa kuqinisekiswa ukuthi iyalingana, ikhono layo lokulwa nokuphazamiseka lingathuthukiswa. Ngokwemithetho yezintambo ezingenhla, isifunda sebhodi lesifunda esiphrintiwe esijwayelekile se-air conditioner siyathuthukiswa futhi silungiselelwe.