Izifinyezo eziyisithupha ze- PCB umklamo wokukhiqiza

1. Ukuhlelwa

Okokuqala, cabanga ngosayizi we-PCB. Lapho usayizi webhodi lesifunda le-PCB likhulu kakhulu, ulayini ophrintiwe mude, i-impedance iyanda, ikhono lokulwa nomsindo liyancipha futhi izindleko ziyanda; Uma incane kakhulu, ukushabalalisa ukushisa akulungile, futhi imigqa eseduze kulula ukuphazamiseka. Ngemuva kokunquma ubukhulu be-PCB, nquma isikhundla sezinto ezikhethekile. Ekugcineni, zonke izingxenye zesifunda zihlelwe ngokuya ngamayunithi wokusebenza wesifunda.

Izimiso ezilandelayo zizobhekwa lapho kunqunywa isikhundla sezinto ezikhethekile:

(1) Fushanisa izintambo eziphakathi kwezinto ezinemvamisa ephezulu ngangokunokwenzeka, bese uzama ukunciphisa imingcele yazo yokusabalalisa nokuphazanyiswa kokuhlangana kwamandla kagesi. Izingxenye ezingena ekuphazanyisweni ngeke zisondelene kakhulu, futhi izinto zokufaka nezokukhipha ziyoba kude ngangokunokwenzeka.

(2) Kungaba nomehluko omkhulu ongaba khona phakathi kwezinye izinto noma izintambo, ngakho-ke ibanga phakathi kwazo kufanele lenyuswe ukuze kugwenywe ngengozi isifunda esifushane esibangelwe ukukhishwa. Izingxenye ezinamandla amakhulu zizohlelwa ezindaweni okungelula ukuzithinta ngesikhathi sokuthumela.

(3) Isikhundla esithathwa yimbobo yokubeka ipuleti eliphrintiwe kanye nokusekelwa okungaguquki kuzogcinwa.

Ngokweyunithi esebenzayo yesekethe, ukwakheka kwazo zonke izingxenye zesekethe kuzothobela le migomo elandelayo:

(1) Hlela indawo yeyunithi ngayinye yesekethe esebenzayo ngokuya kokujikeleza kwesifunda, yenza ukwakheka kube lula ukugeleza kwesiginali, futhi ugcine isignali isiqondise ngendlela efanayo ngangokunokwenzeka.

(2) Thatha izingxenye eziyinhloko zesekethe ngalinye elisebenzayo njengesikhungo nokuhleleka okuzungezile. Izingxenye zizohlelwa ngokulinganayo, ngobunono nangokubumbana ku-PCB. Ukuhola nokuxhumeka phakathi kwezakhi kuzoncishiswa futhi kufushaniswe ngangokunokwenzeka.

(3) Ngokusebenza kwesekethe kumvamisa ophakeme, amapharamitha wokusabalalisa phakathi kwezingxenye kufanele acatshangelwe. Amasekethe ajwayelekile, izingxenye zizohlelwa ngokufana ngangokunokwenzeka. Ngale ndlela, ayisihle kuphela, kepha futhi kulula ukuyihlanganisa nokuyi-weld, futhi kulula ukukhiqiza ngobuningi.

(4) Izingxenye ezitholakala onqenqemeni lwebhodi lesifunda ngokuvamile azikho ngaphansi kuka-2mm kude nonqenqema lwebhodi lesifunda. Ukuma okuhle kwebhodi lesifunda kungunxande. Ubungako besilinganiselo ngu-3: 2 kuye ku-4: 3. Lapho usayizi ongaphezulu webhodi lesifunda ungaphezu kuka-200x150mm, amandla womshini webhodi lesifunda azocatshangelwa.

2. Ukuxhuma

Imigomo ye-wiring imi kanje:

(1) Abaqhubi abasetshenziswa kumatheminali wokufaka nokhipha kufanele bagweme ukufana okusondele eduze ngangokunokwenzeka. Kungcono ukufaka ucingo lwaphansi phakathi kwemigqa ukugwema ukuhlangana kwempendulo.

(2) Ububanzi obuncane bomqhubi ophrintiwe bunqunywa kakhulu ngamandla wokubambelela phakathi kukasaqhubi ne-base base plate kanye ne-current egeleza ngabo.

(3) Ukugoba kocingo oluphrintiwe imvamisa kuyisiyingi esiyindilinga, futhi i-engeli engakwesokudla noma i-engeli efakiwe izothinta ukusebenza kukagesi kwisekethe ephezulu kakhulu. Ngaphezu kwalokho, zama ukugwema ukusebenzisa ucwecwe lwethusi lwendawo enkulu, uma kungenjalo, ukunwetshwa kocwecwe lwethusi nokuwa kulula ukuvela uma kufudunyezwa isikhathi eside. Lapho kufanele kusetshenziswe indawo enkulu yocwecwe lwethusi, kungcono ukusebenzisa isimo segridi, esivumayo ukuqeda igesi eguquguqukayo eyenziwe ukufudumeza kwesinamathelisi esiphakathi kocingo lwethusi kanye ne-substrate.

3. Iphedi

Umgodi wesikhungo sephedi (i-in-line device) sikhulu kancane kunobubanzi bomthofu wedivayisi. Uma iphedi likhulu kakhulu, kulula ukwakha i-soldering yamanga. Ububanzi obungaphandle D bephedi ngokuvamile abubi ngaphansi kuka (D + 1.2) mm, lapho uD kungububanzi bomgodi oholayo. Kumasekethe edijithali anesisindo esiphakeme, ubukhulu obuncane bephedi bungaba (D + 1.0) mm.

Anti ukuphazanyiswa izinyathelo ze-PCB kanye wesifunda:

Idizayini yokulwa nokuphazamiseka yebhodi lesifunda ephrintiwe isondelene kakhulu nesekethe elithile. Lapha, kuchazwa izinyathelo ezimbalwa ezijwayelekile ze-PCB anti-interference design.

1. Ukwakhiwa kwentambo yamandla

Ngokwamanje webhodi lesifunda eliphrintiwe, zama ukukhulisa ububanzi bolayini wamandla futhi unciphise ukumelana neluphu. Ngasikhathi sinye, yenza ukuqondiswa kwentambo yamandla nocingo lomhlabathi luhambisane nesiqondiso sokudluliswa kwedatha, okusiza ukuthuthukisa amandla omsindo wokulwa.

2.Lot design

Izimiso zokwakhiwa kwensimbi yomhlabathi yilezi:

(1) Idijithali ne-analog kwehlukanisiwe. Uma kunombili amasekethe anengqondo kanye namasekhethi aqondile ebhodini lesifunda, azohlukaniswa ngangokunokwenzeka. Iphoyinti elilodwa lokumiswa okulinganayo lizokwamukelwa ukumiswa kwesekethe elinemvamisa ephansi ngangokunokwenzeka. Uma kunzima ukuxhuma i-wiring yangempela, ingaxhunyaniswa kancane ngochungechunge bese ixhunyaniswa ngokufana. I-Multi point series grounding izokwamukelwa isekethe elinemvamisa ephezulu, intambo yomhlabathi kufanele ibe mfushane futhi iqashwe, futhi igridi efana nocwecwe lwendawo enkulu izosetshenziswa ezungeze izingxenye zemvamisa ephezulu ngangokunokwenzeka.

(2) Ucingo oluyisisekelo luyoba bukhulu ngangokunokwenzeka. Uma ucingo lokwakha lwenziwe ngocingo oluthungiwe, amandla okuba phansi aguquka ngokushintsha kwamanje, ukuze ukusebenza komsindo okuphikisayo kunciphe. Ngakho-ke, ucingo oluyisisekelo kufanele luqiniswe ukuze lukwazi ukudlula kathathu njengamanje okuvumelekile ebhodini eliphrintiwe. Uma kunokwenzeka, ucingo oluyisisekelo luzoba ngaphezu kuka-2 ~ 3mm.

(3) Intambo yokwakha yakha iluphu evaliwe. Kumabhodi aphrintiwe akhiwe kuphela ngamasekethe edijithali, isekethe lokumisa lihlelwe ngeqoqo leqoqo, elingathuthukisa ikhono lomsindo eliphikisayo.

4. Decoupling capacitor ukumiswa

Enye yezindlela ezijwayelekile zedizayini ye-PCB ukumisa ama-capacitor wokuqothula afanele engxenyeni ngayinye eyinhloko ye-PCB. Umgomo wokumiswa ojwayelekile wokuqedwa kwe-capacitor ngu:

(1) Itheminali yokufaka amandla ixhunywe nge-10 ~ 100uF capacitor electrolytic. Uma kungenzeka, kungcono ukuxhuma ngaphezu kwe-100uF.

(2) Ngokomthetho, i-chip yesekethe ehlanganisiwe ngayinye kufanele ifakwe i-0.01uF ~ 0.1uF ceramic chip capacitor. Uma kwenzeka kukhona igebe elinganele ebhodini eliphrintiwe, i-1 ~ 10PF capacitor ingahlelwa njalo ngama-chips angama-4 ~ 8.

(3) Kumadivayisi anokumelana nomsindo obuthakathaka nokushintsha kwamandla amakhulu ngesikhathi sokuvala, njengamadivayisi wesitoreji se-RAM ne-ROM, ama-capacitor wokuqhaqhaqhaza azoxhunywa ngqo phakathi kwentambo yamandla nentambo yomhlabathi ye-chip.

5. Ngokusebenzisa imbobo design

Ekuklanyweni kwe-PCB enejubane elikhulu, ama-vias abonakala elula avame ukuletha imiphumela emibi ekwakhiweni kwesifunda. Ukuze sinciphise imiphumela emibi ebangelwe yimiphumela yesinanakazana yama-vias, singazama konke okusemandleni ekwakhiweni

(1) Uma kubhekwa izindleko nekhwalithi yesiginali, kukhethwa okulinganayo ngosayizi. Isibonelo, ngokuklanywa kwememori engu-6-10 yemodyuli yememori, kungcono ukukhetha ama-vias ayi-10 / 20MIL (ukubhola / pad). Kwamanye amabhodi osayizi abancane kakhulu, ungazama futhi ukusebenzisa ama-vii ayi-8 / 18mil. Ngaphansi kwezimo zobuchwepheshe zamanje, kunzima ukusebenzisa okuncane ngemigodi (lapho ukujula komgodi kudlula izikhathi eziyisithupha ububanzi bokubhola, akunakwenzeka ukuqinisekisa ukuthi udonga lomgodi lungagqokiswa ngokufana ngethusi); Okwe-vias kwamandla noma komhlaba, usayizi omkhulu ungacatshangwa ukunciphisa impedance

(2) Ukuhanjiswa kwesiginali ebhodini le-PCB ngeke kushintshe izingqimba ngangokunokwenzeka, okungukuthi, ama-vias angadingekile ngeke asetshenziswe ngangokunokwenzeka

(3) Izikhonkwane zokuphakelwa kukagesi kanye nomhlabathi kufanele kuboshwe eduze. Okufushane ukuhola phakathi kokungena nephini, kungcono

(4) Beka amanye ama-vias agxilile eduze kwama-vias wokushintshwa koqweqwe lwesiginali ukunikeza isekethe eseduzane yesiginali. Ungakwazi ngisho nokubeka inani elikhulu lama-vias angasasebenzi ku-PCB

6.Okunye okuhlangenwe nakho ekwehliseni umsindo nokuphazamiseka kukagesi

(1) Uma ungasebenzisa ama-chip anejubane eliphansi, awudingi lawo anejubane eliphezulu. Ama-chip ashesha kakhulu asetshenziswa ezindaweni ezibalulekile

(2) Uchungechunge lwama-resistors lungasetshenziswa ukunciphisa izinga lokugxuma emaphethelweni aphezulu nangaphansi wesekethe yokulawula.

(3) Zama ukuhlinzeka ngohlobo oluthile lokudampasi lokudluliswa, njll

(4) Sebenzisa iwashi lemvamisa eliphansi kakhulu elihlangabezana nezidingo zohlelo.

(5) Iwashi lizoba seduze ngangokunokwenzeka nedivayisi kusetshenziswa iwashi. Igobolondo le-quartz crystal oscillator lizobekwa phansi. Indawo yewashi izungezwe ngocingo lomhlabathi. Ulayini wewashi uzoba mfushane ngangokunokwenzeka. Ngeke kube khona izintambo ngaphansi kwekristalu le-quartz nangaphansi kwensimbi ezwelayo yomsindo. Amasignali wokukhetha iwashi, ibhasi ne-chip azoba kude nolayini ne-connector. Ukuphazanyiswa kolayini wewashi oqonde ngqo kulayini we-I / O kuncane kunalokho okufana nomugqa we-I / O

(6) Ukuphela kokufakwa kwesekethe lesango elingasetshenziswanga ngeke kumiswe, ukuphela kokufaka okuhle kwesikhulisi sokusebenza esingasetshenziswanga kuzobekwa phansi, kuthi ukuphela kokufaka okungekuhle kuxhunywe ekugcineni kokukhiphayo