chimodzi Lingaliro lofunikira pakuwonongeka

Kudzera mu bowo (VIA) ndi gawo lofunikira la Multilayer PCB, ndipo mtengo wamabowo obowola nthawi zambiri umakhala wa 30% mpaka 40% yamtengo wopangira board ya PCB. Mwachidule, dzenje lililonse pa PCB lingatchulidwe kuti liwiro. Potengera magwiridwe antchito, bowo litha kugawidwa m’magulu awiri: limodzi limagwiritsidwa ntchito polumikizira magetsi pakati pa zigawo; Wina amagwiritsidwa ntchito pokonza kapena kuyika zida. Potengera ndondomekoyi, mabowo obowolokawa amagawika m’magulu atatu, omwe ndi akhungu kudzera, oyikidwa m’manda kudzera kudzera. Mabowo akhungu ali pamwamba ndi pansi pa bolodi la PRINTED dera lanu ndipo mumakhala ndi kuya kwakukulumikizira dera loyandikana ndi dera lamkati pansipa. Kuzama kwa mabowo nthawi zambiri sikudutsa gawo lina (kabowo). Mabowo omwe adakwiriridwa ndi mabowo olumikizirana mkatikati mwa bolodi losindikizidwa lomwe silifikira pamwamba pa bolodi loyenda. Mitundu iwiri yamabowo ili mkatikati mwa bolodi, yomwe imamalizidwa ndi makina osanjikiza asanapangidwe, ndipo zigawo zingapo zamkati zimatha kudzilumikizana pakapangidwe kabowo. Mtundu wachitatu, womwe umatchedwa mabowo, umadutsa pa bolodi lonselo ndipo ungagwiritsidwe ntchito kulumikizana kwamkati kapena kukweza ndikupeza mabowo azinthu zina. Chifukwa dzenje limakhala losavuta kugwiritsa ntchito pochita izi, mtengo wake ndi wotsika, motero matabwa ambiri osindikizidwa amawagwiritsa ntchito, osati mitundu ina iwiri yodutsira. Otsatira kudzera m’mabowo, popanda kufotokozera mwapadera, adzawerengedwa ngati kudzera m’mabowo.

PCB kudzera mu mfundo yoyambira komanso kudzera mu njira yoyambira

Kuchokera pamawonekedwe apangidwe, bowo lodutsa-bowo limapangidwa makamaka ndi magawo awiri, imodzi ndi dzenje lobowola pakati, ndipo linalo ndi malo ozungulira pobowola. Kukula kwa magawo awiriwa kumatsimikizira kukula kwa dzenje. Zachidziwikire, pakupanga kwa liwiro lalikulu, kachulukidwe ka PCB, wopanga nthawi zonse amafuna kuti dzenje likhale laling’ono momwe zingathere, chitsanzochi chimatha kusiya malo owongolera, kuwonjezera pamenepo, dzenje laling’ono, mphamvu yake ya parasitic ndiyocheperako, zambiri oyenera dera othamanga kwambiri. Koma kuchepetsa kukula kwa dzenje nthawi yomweyo kumabweretsa kukwera mtengo, ndipo kukula kwa dzenje sikungachepetsedwe popanda malire, kumangolekezera pobowola (kubowola) ndi kuyika (plating) ndi ukadaulo wina: zing’onozing’ono dzenje, nthawi yotalikirapo pakubowola, ndikosavuta kuchoka pamalo apakati; Pamene kuya kwa dzenje kumakhala kopitilira kasanu ndi kawiri kupingasa kwa dzenje, ndikosatheka kutsimikizira mayikidwe amkuwa a khoma loboola. Mwachitsanzo, ngati makulidwe (kupyolera-bowo) kwa bolodi ya PCB yosanjikiza 6 ndi 50Mil, ndiye kuti dzenje locheperako lomwe opanga PCB angapereke ndi 8Mil. Ndi chitukuko cha ukadaulo wa kubowola laser, kukula kwa kubowola kumatha kukhala kocheperako komanso kocheperako. Nthawi zambiri, m’mimba mwake wa dzenje ndi wocheperako kapena wofanana ndi 6Mils, timachitcha kuti microhole. Ma Microholes amagwiritsidwa ntchito popanga HDI (high density Interconnect structure). Ukadaulo wa Microhole umalola kuti dzenje ligundidwe mwachindunji pa pad (VIA-in-pad), zomwe zimathandizira kwambiri magwiridwe antchito a dera ndikusunga ma waya.

Kupyolera-bowo pamzere wopatsira ndi malo opumira a impedance discontinuity, zomwe zingayambitse chiwonetsero cha chizindikiro. Nthawi zambiri, kutsekeka kofananira kwa dzenje kumakhala pafupifupi 12% poyerekeza ndi kolowera. Mwachitsanzo, kutsekeka kwa mzere wotumizira wa 50ohm kudzachepa ndi 6 ohm ikadutsa pabowo (chachindunji chimagwirizananso ndi kukula kwa dzenje ndi makulidwe a mbale, koma osati kuchepa kwathunthu). Komabe, kusinkhasinkha komwe kumayambitsidwa ndi kutha kwa impedance kudzera mu bowo ndilocheperako, ndipo mawonekedwe ake owonetsera ali kokha: (44-50) / (44 + 50) = 0.06. Mavuto obwera chifukwa cha dzenje amayang’ana kwambiri mphamvu ya parasitic capacitance ndi inductance.

Parasitic capacitance ndi inductance kupyolera mu dzenje

The parasitic osokera capacitance alipo mu dzenje lokha. Ngati m’mimba mwake wa zone kuwotcherera kukana wa dzenje pa kusanjikiza wosanjikiza ndi D2, awiri a kuwotcherera PAD ndi D1, makulidwe a bolodi PCB ndi T, ndi dielectric zonse gawo lapansi ndi ε, ndi parasitic capacitance. dzenjelo ndi pafupifupi C=1.41εTD1/ (D2-D1).

Mphamvu yayikulu yamphamvu yama parasitic pakuzungulira ndikuchulukitsa nthawi yakukwera ndi kuchepetsa liwiro la dera. Mwachitsanzo, pa bolodi la PCB lokhala ndi makulidwe a 50Mil, ngati m’mimba mwake wa bowolo ndi 20Mil (m’mimba mwake wa borehole ndi 10Mils) ndipo m’mimba mwake wa chipika chogulitsira ndi 40Mil, titha kuyerekeza mphamvu ya parasitic. njira yodutsamo ndi formula yomwe ili pamwambapa: C=1.41×4.4×0.050×0.020/ (0.040-0.020) =0.31pF kusintha kwa nthawi yokwera chifukwa cha kuthekera kuli motere: T10-90 = 2.2c (Z0/2) =2.2×0.31x (50/2) =17.05ps Kuchokera pazikhalidwezi, zikhoza kuwoneka kuti ngakhale zotsatira za kuchedwa kukwera ndi kuchepetsa chifukwa cha parasitic capacitance ya single through- dzenje silodziwikiratu, ngati bowolo likugwiritsidwa ntchito posintha pakati pa zigawo kangapo, mabowo angapo adzagwiritsidwa ntchito. Samalani pamapangidwe anu. Pakupanga kothandiza, mphamvu ya parasitic imatha kuchepetsedwa powonjezera mtunda pakati pa dzenje ndi malo oyika mkuwa (anti-pad) kapena kuchepetsa kutalika kwa pedi. Popanga makina othamanga kwambiri a digito, kulowetsedwa kwa parasitic pabowo kumawononga kwambiri kuposa mphamvu ya parasitic. Makina ake amtundu wa parasitic adzafooketsa kuperekera kwa capacitance ndikuchepetsa kusefa kwa mphamvu yonse. Titha kungowerengera kuchuluka kwa ma parasitic pakuyerekeza kwa dzenje pogwiritsa ntchito njira yoyeserera iyi: L=5.08h [ln (4h/d) +1]

Pamene L amatanthauza kulowetsa kwa dzenje, H ndi kutalika kwa dzenje, ndipo D ndi m’mimba mwake wa dzenje lapakati. Zitha kuwonedwa kuchokera ku equation kuti kukula kwa dzenje kumakhudza pang’ono pakulowerera, pomwe kutalika kwa dzenje kumakhudza kwambiri kutulutsa. Pogwiritsa ntchito chitsanzo pamwambapa, inductance kunja kwa dzenje ikhoza kuwerengedwa motere:

L = 5.08 × 0.050 [ln (4 × 0.050 / 0.010) +1] = 1.015nh Ngati chizindikiro chokwera nthawi ndi 1ns, ndiye kuti kukula kwa impedance ndiko: XL = πL/T10-90 = 3.19 ω. Kutayika kumeneku sikunganyalanyazidwe pakadali pano pafupipafupi. Makamaka, the capacitor yodutsa imayenera kudutsa m’mabowo awiri kuti agwirizane ndi kapangidwe kazomwe amapangidwazo, motero kuwirikiza kawiri kubowoleza kwa tiziromboti.

Katatu, momwe mungagwiritsire ntchito dzenje

Kudzera pakuwunika pamwambapa kwa ziwombankhanga za mabowo oyenda, titha kuwona kuti pamapangidwe a PCB othamanga kwambiri, mabowo omwe amawoneka ngati osavuta nthawi zambiri amabweretsa zoyipa zazikulu pakupanga dera. Pofuna kuchepetsa zovuta zoyipa zakutuluka kwa dzenje, titha kuyesa kuchita izi motengera kapangidwe kake:

1. Poganizira mtengo ndi mtundu wa chizindikiro, kukula kwa dzenje koyenera kumasankhidwa. Ngati ndi kotheka, ganizirani kugwiritsa ntchito mabowo amitundu yosiyanasiyana. Mwachitsanzo, pazingwe zamagetsi kapena pansi, ganizirani kugwiritsa ntchito miyeso yokulirapo kuti muchepetse kutsekeka, komanso polumikizira ma waya, gwiritsani ntchito mabowo ang’onoang’ono. Zoonadi, pamene kukula kwa dzenje kumachepa, mtengo wofananawo udzawonjezeka.

2. Njira ziwiri zomwe takambiranazi zikuwonetsa kuti kugwiritsa ntchito matabwa ocheperako a PCB kumathandiza kuchepetsa magawo awiri a parasitic a perforations.

3. Mawaya a chizindikiro pa bolodi la PCB sayenera kusintha zigawo momwe angathere, ndiye kuti, musagwiritse ntchito mabowo osafunika momwe mungathere.

4. Zikhomo za magetsi ndi nthaka ziyenera kuponyedwa mu dzenje lapafupi, ndipo kutsogolo pakati pa dzenje ndi zikhomo ziyenera kukhala zazifupi momwe zingathere. Mabowo angapo amatha kuganiziridwa mofananira kuti achepetse inductance yofanana.

5. Mabowo ena apansi amayikidwa pafupi ndi mabowo a chizindikiro chosanjikiza kuti apereke kuzungulira kwapafupi kwa chizindikirocho. Mutha kuyika mabowo enanso ambiri pa PCB. Zachidziwikire, muyenera kukhala osinthasintha kapangidwe kanu. Mtundu wa dzenje lomwe tafotokozali pamwambapa ndi momwe mumakhalira mapepala aliyense wosanjikiza. Nthawi zina, titha kuchepetsa kapena kuchotsa ma pads m’malo ena. Makamaka pakakhala kuchuluka kwa dzenje ndilokulirapo, zimatha kupangitsa kuti pakhale poyambira podula mzere wamkuwa, kuti athetse vutoli kuphatikiza pakusuntha kwa dzenje, titha kuganiziranso za dzenje muzitsulo zamkuwa kuti muchepetse kukula kwa pad.

6. Kwa matabwa othamanga kwambiri a PCB okhala ndi kachulukidwe kakang’ono, mabowo ang’onoang’ono amatha kuganiziridwa.