One Umqondo oyisisekelo wokubhoboza

Nge hole (VIA) kuyingxenye ebalulekile ye- I-Multilayer PCB, futhi izindleko zemigodi yokumba zivame ukubalwa ngama-30% kuya ku-40% wezindleko zokwenza ibhodi le-PCB. Kalula nje, yonke imbobo ku-PCB ingabizwa ngokuthi umgodi wokudlula. Ngokuya ngomsebenzi, umgodi ungahlukaniswa ngezigaba ezimbili: esisodwa sisetshenziselwa ukuxhumana kagesi phakathi kwezendlalelo; Enye isetshenziselwa ukulungisa idivayisi noma ukuma. Ngokwenqubo, lezi zimbobo ezihlukaniswayo ngokuvamile zihlukaniswe izigaba ezintathu, okungukuthi, i-blind via, ingcwatshwe nge-through nange-through. Izimbobo eziyimpumputhe zitholakala ezindaweni eziphezulu nezingezansi zebhodi lesifunda elinyathelisiwe futhi zinokujula okuthile kokuxhuma isifunda esingaphezulu kwesifunda esingaphakathi ngezansi. Ukujula kwemigodi imvamisa akweqi isilinganiso esithile (ukuvula). Izimbobo ezingcwatshwe izimbobo zokuxhuma kusendlalelo sangaphakathi sebhodi lesifunda eliphrintiwe elingadluli ebusweni bebhodi lesifunda eliphrintiwe. Izinhlobo ezimbili zezimbobo zitholakala engxenyeni yangaphakathi yebhodi lesifunda, eligcwaliswa ngenqubo yokubumba emgodini ngaphambi kokuhlungwa, futhi izingqimba eziningana zangaphakathi zingagqitshwa ngesikhathi kwakhiwa imbobo. Uhlobo lwesithathu, olubizwa nge-through-hole, ligijima kulo lonke ibhodi lesifunda futhi lungasetshenziselwa ukuxhumana kwangaphakathi noma njengokufaka nokuthola izimbobo zezinto ezithile. Ngoba umgodi wokungena kulula ukuwusebenzisa kule nqubo, izindleko ziphansi, ngakho-ke amabhodi wesifunda amaningi aprintiwe ayayisebenzisa, kunezinye izinhlobo ezimbili zomgodi. Lokhu okulandelayo ngemigodi, ngaphandle kwencazelo ekhethekile, kuzobhekwa njengokungena emigodini.

PCB ngokusebenzisa imbobo umqondo eziyisisekelo futhi ngokusebenzisa imbobo indlela isingeniso

Ngokombono wokuklama, imbobo yokubhoboza ikakhulukazi yakhiwe izingxenye ezimbili, enye imbobo yokubhoboza phakathi, kanti enye iyindawo yephedi ezungeze umgodi wokubhoboza. Usayizi walezi zingxenye ezimbili unquma usayizi wembobo edlulayo. Ngokusobala, ekwakhiweni kwe-high-speed, high-density PCB, umklami uhlala efuna ukuthi umgodi ube mncane ngangokunokwenzeka, lesi sampuli singashiya isikhala sokwengeza izintambo, ngaphezu kwalokho, okuncane emgodini, amandla aso okuphila kwezinambuzane mancane, ngaphezulu ifanele isifunda esinejubane elikhulu. Kodwa ukuncishiswa kosayizi wembobo ngesikhathi esifanayo kuletha ukwanda kwezindleko, futhi ubukhulu bomgodi abukwazi ukuncishiswa ngaphandle komkhawulo, bunqunyelwe ngokubhoboza (ukubhoboza) nokucwenga (plating) nobunye ubuchwepheshe: imbobo encane, isikhathi eside esithathayo ukubhola, kuba lula ukuchezuka endaweni ephakathi; Lapho ukujula komgodi kuphindwe izikhathi ezingaphezu kwezingu-6 ububanzi bomgodi, akunakwenzeka ukuqinisekisa ukufakwa kopende ofanayo wodonga lomgodi. Isibonelo, uma ukushuba (ngembobo ukujula) kwebhodi elijwayelekile le-6-ungqimba le-PCB kungu-50Mil, khona-ke ubukhulu bomgodi obuncane abakhiqizi be-PCB abanganikeza ngabo yi-8Mil. Ngokuthuthuka kobuchwepheshe bokugaya nge-laser, ubukhulu bokubhoboza bungaba buncane futhi bube buncane. Ngokuvamile, ububanzi bomgodi bungaphansi noma bulingana no-6Mils, sikubiza ngokuthi yi-micro hole. Ama-Microholes avame ukusetshenziswa ekwakhiweni kwe-HDI (high density Interconnect structure). Ubuchwepheshe beMicrohole buvumela umgodi ukuthi ushaywe ngqo kuphedi (i-VIA-in-pad), okuthuthukisa kakhulu ukusebenza kwesifunda futhi kulondoloze isikhala sokwenza izintambo.

Imbobo ekulayini wokudlulisela iyindawo yokuphumula yokunqanyulwa kwe-impedance, okuzobangela ukubonakaliswa kwesignali. Ngokuvamile, ukuthintana okulingana kwembobo yokudlula cishe kungaphansi ngo-12% kunaleyo yolayini wokudlulisela. Isibonelo, impedance yomugqa wokudlulisa we-50ohm uzokwehla ngo-6 ohm lapho udlula emgodini ophakathi (okucacisiwe futhi kuhlobene nosayizi wembobo yokudlula nosayizi wepuleti, kepha hhayi ukwehla ngokuphelele). Kodwa-ke, ukuboniswa okubangelwa ukungaqhubeki kokubambezeleka ngembobo empeleni kuncane kakhulu, futhi i-reflection coefficient yakhona kuphela :(44-50)/(44+50) =0.06. Izinkinga ezibangelwa umgodi zigxile kakhulu ethonyeni le-parasitic capacitance kanye ne-inductance.

I-Parasitic capacitance kanye ne-inductance ngokusebenzisa imbobo

I-parasitic stray capacitance ikhona emgodini ngokwawo. Uma ububanzi bendawo yokumelana ne-welding yembobo kungqimba lokubeka kungu-D2, ububanzi bephedi yokushisela yi-D1, ubukhulu bebhodi le-PCB ngu-T, kanti i-dielectric constant ye-substrate ingu-ε, amandla e-parasitic umgodi cishe u-C=1.41εTD1/ (D2-D1).

Umphumela oyinhloko we-capacitance yama-parasitic ukwengeza isikhathi sokunyuka kwesiginali nokunciphisa ijubane lesifunda. Isibonelo, ebhodini le-PCB elinogqinsi oluyi-50Mil, uma ububanzi bephedi yembobo engu-20Mil (ububanzi bomgodi buyi-10Mils) nobubanzi bebhulokhi ye-solder bungama-40Mil, singalinganisa amandla e-parasitic imbobo ngefomula engenhla: C = 1.41 × 4.4 × 0.050 × 0.020 / (0.040-0.020) = 0.31pF ushintsho lwesikhathi sokuphakama olubangelwa yi-capacitance cishe lumi kanje: T10-90= 2.2c (Z0/2) =2.2×0.31x (50/2) =17.05ps Kusukela kulawa manani, kungabonakala ukuthi nakuba umphumela wokulibaziseka okukhuphukayo kanye nokwehla okubangelwa amandla e-parasitic we-single through- umgodi awubonakali kahle, uma imbobo yokudlula isetshenziselwa ukushintsha phakathi kwezingqimba izikhathi eziningi, kuzosetshenziswa izimbobo eziningi. Qaphela ekwakhiweni kwakho. Ngokuklama okusebenzayo, i-parasitic capacitance ingancishiswa ngokukhulisa ibanga phakathi kwembobo nendawo yokubeka yethusi (i-anti-pad) noma ngokunciphisa ububanzi bephedi. Ekwakhekeni kwesekethe yedijithali enesivinini esikhulu, i-parasitic inductance of the through-hole iyingozi kakhulu kunaleyo ye-parasitic capacitance. Ukungeniswa kwayo kochungechunge lwe-parasitic kuzothena amandla umnikelo we-bypass capacitance futhi kunciphise ukusebenza kokuhlunga kohlelo lonke lwamandla. Singamane sibale ukungeniswa kwe-parasitic kokulinganisa kwembobo sisebenzisa le fomula ye-empirical elandelayo: L=5.08h [ln (4h/d) +1]

Lapho u-L ebhekisela ekungeneni kwembobo, u-H ubude bembobo, futhi u-D uwububanzi bembobo emaphakathi. Kungabonakala kusukela ku-equation ukuthi ububanzi bomgodi bunomthelela omncane ekungenisweni, ngenkathi ubude bomgodi bunomthelela omkhulu ekungenisweni. Usasebenzisa isibonelo esingenhla, i-inductance ephuma emgodini ingabalwa ngokuthi:

L=5.08×0.050 [ln (4×0.050/0.010) +1] = 1.015nh Uma isikhathi sokukhuphuka kwesignali singama-1ns, khona-ke usayizi we-impedance olinganayo ngu: XL=πL/T10-90=3.19 ω. Le impedance ayinakunakwa lapho kukhona imvamisa ephezulu yamanje. Ikakhulu, i-bypass capacitor kufanele idlule emigodini emibili yokuxhuma ungqimba lokuphakelwa ekwakhekeni, ngaleyo ndlela iphindwe kabili ukufakelwa kwesinambuzane somgodi.

Okwesithathu, indlela yokusebenzisa imbobo

Ngokuhlaziya okungenhla kwezici ze-parasitic zemigodi edlulayo, singabona ukuthi ekwakhiweni kwe-PCB enesivinini esikhulu, izimbobo ezibonakala zilula ngokuvamile ziletha imiphumela emibi kakhulu ekwakhiweni kwesekethe. Ukuze sinciphise imiphumela emibi yomphumela wezinambuzane zomgodi, singazama ukwenza ngokulandelayo ekwakhiweni:

1. Ngokucabangela izindleko nekhwalithi yesignali, usayizi wembobo onengqondo uyakhethwa. Uma kunesidingo, cabanga ukusebenzisa osayizi abahlukene bezimbobo. Isibonelo, kumakhebuli kagesi noma aphansi, cabanga ukusebenzisa osayizi abakhulu ukuze unciphise i-impedance, kanye nezintambo zesignali, sebenzisa izimbobo ezincane. Yiqiniso, njengoba usayizi wembobo uyancipha, izindleko ezihambisanayo zizokhula.

2. Amafomula amabili okukhulunywe ngawo ngenhla abonisa ukuthi ukusetshenziswa kwamabhodi amancane e-PCB kusiza ukunciphisa amapharamitha amabili e-parasitic of the perforations.

3. Izintambo zesignali ebhodini le-PCB akufanele ziguqule izendlalelo ngangokunokwenzeka, okusho ukuthi, ungasebenzisi izimbobo ezingadingekile ngangokunokwenzeka.

4. Izikhonkwane zokunikezwa kwamandla kanye nomhlabathi kufanele zibhojwe emgodini oseduze, futhi ukuhola phakathi kwembobo nezikhonkwane kufanele kube kufushane ngangokunokwenzeka. Izimbobo ezinqamula eziningi zingabhekwa ngokufana ukunciphisa ukwehliswa okulinganayo.

5. Ezinye izimbobo zaphansi zibekwe eduze kwezimbobo zokwendlaleka kwesignali ukuze kuhlinzekwe iluphu eseduze yesiginali. Ungafaka nezimbobo eziningi ezingeziwe ku-PCB. Vele, udinga ukuguquguquka ekwakhiweni kwakho. Imodeli yembobo okuxoxwa ngayo ngenhla yisimo lapho kunamapads kusendlalelo ngasinye. Kwesinye isikhathi, singanciphisa noma sisuse amapayipi kwezinye izingqimba. Ikakhulukazi esimweni sokuminyana komgodi sikhulu kakhulu, kungaholela ekwakhiweni komsele wesifunda osikiwe kungqimba lwethusi, ukuxazulula inkinga enjalo ngaphezu kokuhambisa indawo yomgodi, singacabanga nangembobo kusendlalelo sethusi ukunciphisa usayizi wephedi.

6. Kumabhodi e-PCB aphezulu – anesivinini esikhulu, izimbobo ezincane zingacatshangelwa.