The kudzera ndi chimodzi mwa zigawo zofunika za Mipikisano wosanjikiza PCB, ndi mtengo kubowola zambiri nkhani 30% kuti 40% ya mtengo wa PCB bolodi. Mwachidule, dzenje lililonse pa PCB limatha kutchedwa kudzera.
The Basic concept of the via:
Kuchokera pamawonedwe a ntchito, kudzera pazigawo ziwiri: imodzi imagwiritsidwa ntchito ngati kugwirizana kwamagetsi pakati pa zigawo, ndipo ina imagwiritsidwa ntchito ngati kukonza kapena kuika chipangizocho. Ngati kuchokera ku ndondomekoyi, mabowowa amagawidwa m'magulu atatu, omwe ndi mabowo akhungu, mabowo okwiriridwa ndi mabowo.
Mabowo akhungu ali pamwamba ndi pansi pamwamba pa bolodi losindikizidwa dera ndipo ali ndi kuya kwa kugwirizana kwa dera pamwamba ndi dera lamkati m'munsimu, ndi kuya kwa mabowo nthawi zambiri si upambana chiŵerengero (kabowo).
dzenje m'manda amatanthauza dzenje kugwirizana lili mkati wosanjikiza gulu losindikizidwa dera, amene sapitirira pamwamba pa bolodi. Pamwambapa mitundu iwiri ya mabowo zili mu wosanjikiza wamkati wa bolodi dera, amene anamaliza ndi kudzera dzenje akamaumba ndondomeko pamaso lamination, ndi zigawo zingapo zamkati akhoza anatayana pa mapangidwe kudzera dzenje.
Mtundu wachitatu umatchedwa kudzera-mabowo, amene kudutsa gulu lonse dera ndipo angagwiritsidwe ntchito kukwaniritsa interconnection mkati kapena ngati unsembe udindo mabowo zigawo zikuluzikulu. Chifukwa chodutsa dzenje ndi chosavuta kukwaniritsa pochitapo kanthu ndipo mtengo wake ndi wotsika, matabwa ambiri osindikizidwa amawagwiritsa ntchito, osati ena awiriwo kudzera mabowo. Mabowo otsatirawa, popanda malangizo apadera, amatengedwa ngati kudzera m'mabowo.
Kuchokera pamawonekedwe apangidwe, njira yodutsa imapangidwa makamaka ndi magawo awiri, imodzi ndi pakati pa dzenje lobowola, ndipo ina ndi malo opangira zowotcherera pozungulira dzenje lobowola. Kukula kwa magawo awiriwa kumatsimikizira kukula kwa via.
Mwachiwonekere, mu mapangidwe apamwamba kwambiri, apamwamba kwambiri a PCB, opanga nthawi zonse amafuna dzenje laling'ono momwe angathere, kotero kuti malo ambiri opangira mawaya atha kutsalira, kuwonjezerapo, ang'onoang'ono kudzera, mphamvu yake ya parasitic ndi yaying'ono, yoyenera kwambiri. kwa mabwalo othamanga kwambiri.
Komabe, kuchepetsedwa kwa kukula kwa kudzera kumabweretsanso kuwonjezeka kwa ndalama, ndipo kukula kwa dzenje sikungachepetsedwe mpaka kalekale, kumachepetsedwa ndi kubowola ndi teknoloji ya electroplating: dzenje laling'ono, nthawi yayitali kubowola, kumakhala kosavuta. ndi kupatuka pakati; Pamene kuya kwa dzenje kumakhala kopitilira 6 m'mimba mwake mwa dzenje, ndizosatheka kuonetsetsa kuti khoma la dzenjelo likhoza kupangidwa mofanana ndi mkuwa.
Mwachitsanzo, ngati makulidwe (kupyolera mu dzenje lakuya) kwa bolodi ya PCB yosanjikiza 6 ndi 50Mil, ndiye kuti kuchuluka kwa kubowola komwe opanga PCB angapereke m'mikhalidwe yabwino kumatha kufika 8Mil. Ndi chitukuko cha ukadaulo wa kubowola laser, kukula kwa kubowola kumathanso kukhala kocheperako komanso kocheperako, ndipo m'mimba mwake mwa dzenje nthawi zambiri amakhala osakwana kapena ofanana ndi 6Mils, timatchedwa ma microholes.
Ma Microholes amagwiritsidwa ntchito popanga HDI (high density interconnect structure), ndipo ukadaulo wa microhole ukhoza kulola dzenje kuti libowoledwe mwachindunji pa pad, zomwe zimathandizira kwambiri magwiridwe antchito ndikusunga ma waya. Kudutsa kumawoneka ngati choduka cha kutha kwa kuyimitsa pa chingwe chotumizira, kupangitsa chiwonetsero cha chizindikiro. Nthawi zambiri, kutsekeka kofanana kwa dzenje kumakhala pafupifupi 12% kutsika kuposa chingwe chopatsira, mwachitsanzo, kutsekeka kwa chingwe cha 50 ohms kuchepetsedwa ndi 6 ohms ikadutsa dzenje (makamaka ndi kukula kwake, makulidwe a mbale amalumikizananso, osati kuchepetsedwa kwathunthu).
Komabe, kuwunikira komwe kumabwera chifukwa cha kutha kwa kulephera kupitilira kumakhala kochepa kwambiri, ndipo mawonekedwe ake ndi okhawo:
(44-50)/(44 + 50) = 0.06
Mavuto omwe amabwera chifukwa cha via amayang'ana kwambiri pazovuta za parasitic capacitance ndi inductance.
Via's Parasitic capacitance ndi Inductance
Pali parasitic osokera capacitance mu kudzera palokha. Ngati m'mimba mwake wa zone kukana solder pa wosanjikiza anaika ndi D2, awiri a solder pad ndi D1, makulidwe a bolodi PCB ndi T, ndi dielectric mosalekeza wa gawo lapansi ndi ε, parasitic capacitance wa kudzera dzenje. pafupifupi:
C=1.41εTD1/(D2-D1)
Chotsatira chachikulu cha parasitic capacitance pa dera ndikutalikitsa nthawi yowonjezereka ya chizindikiro ndi kuchepetsa liwiro la dera.
Mwachitsanzo, kwa PCB yokhala ndi makulidwe a 50Mil, ngati m'mimba mwake mwa pad ndi 20Mil (m'mimba mwake wa dzenje lobowola ndi 10Mils) ndipo m'mimba mwake malo okanira solder ndi 40Mil, ndiye kuti titha kuyerekeza mphamvu ya parasitic. kudzera mwa njira yomwe ili pamwambapa:
C=1.41x4.4x0.050x0.020/(0.040-0.020)=0.31pF
Kuchuluka kwa kusintha kwa nthawi yowonjezereka chifukwa cha gawo ili la capacitance ndi pafupifupi:
T10-90=2.2C(Z0/2)=2.2x0.31x(50/2)=17.05ps
Zitha kuwoneka kuchokera kuzinthu izi kuti ngakhale kugwiritsidwa ntchito kwa kuchedwa kwakukwera komwe kumachitika chifukwa cha mphamvu ya parasitic ya imodzi kudzera sizodziwikiratu, ngati njirayo imagwiritsidwa ntchito kangapo pamzere kusinthana pakati pa zigawo, mabowo angapo adzagwiritsidwa ntchito, ndipo mapangidwewo ayenera kuganiziridwa bwino. Mu mapangidwe enieni, mphamvu ya parasitic imatha kuchepetsedwa powonjezera mtunda pakati pa dzenje ndi dera lamkuwa (Anti-pad) kapena kuchepetsa m'mimba mwake.
Popanga mabwalo othamanga kwambiri a digito, kuvulaza komwe kumachitika chifukwa cha parasitic inductance nthawi zambiri kumakhala kokulirapo kuposa mphamvu ya parasitic capacitance. Zotsatira zake za parasitic inductance zidzafooketsa chothandizira cha bypass capacitor ndikufooketsa kusefa kwadongosolo lonse lamphamvu.
Titha kugwiritsa ntchito njira zotsatirazi kuti tingowerengera kuchuluka kwa ma parasitic inductance of a through-hole approximation:
L=5.08h[ln(4h/d)+1]
Pamene L amatanthawuza kulowetsa kwa via, h ndi kutalika kwa via, ndipo d ndi m'mimba mwake wa dzenje lapakati. Zitha kuwoneka kuchokera munjira yoti makulidwe a via ali ndi mphamvu zochepa pa inductance, pomwe kutalika kwa via kumakhudza kwambiri inductance. Pogwiritsa ntchito chitsanzo pamwambapa, inductance ya kunja kwa dzenje ikhoza kuwerengedwa motere:
L=5.08x0.050[ln(4x0.050/0.010)+1]=1.015nH
Ngati nthawi yowonjezereka ya chizindikiro ndi 1ns, ndiye kuti kukula kwake kofanana ndi:
XL=πL/T10-90=3.19Ω
Kulepheretsa kotereku sikunganyalanyazidwe pamaso pa ma frequency apamwamba kwambiri kudzera, makamaka, dziwani kuti chodutsa chodutsacho chiyenera kudutsa mabowo awiri pogwirizanitsa mphamvu yosanjikiza ndi mapangidwe, kotero kuti inductance ya parasitic ya dzenje idzachulukitsidwa.
Momwe mungagwiritsire ntchito via?
Kupyolera mu kusanthula pamwamba pa makhalidwe parasitic dzenje, titha kuona kuti mkulu-liwiro PCB mapangidwe, mabowo ooneka osavuta nthawi zambiri kumabweretsa zotsatira zoipa kwambiri mapangidwe dera. Pofuna kuchepetsa zovuta zomwe zimachitika chifukwa cha parasitic zotsatira za dzenje, mapangidwewo akhoza kukhala momwe angathere:
Kuchokera ku mbali ziwiri za mtengo ndi mtundu wa chizindikiro, sankhani kukula koyenera kwa kukula kwake. Ngati ndi kotheka, mukhoza kuganizira ntchito miyeso yosiyanasiyana ya vias, monga kwa magetsi kapena mabowo pansi waya, mukhoza kuganizira ntchito yaikulu kukula kuchepetsa impedance, ndi mawaya chizindikiro, mungagwiritse ntchito ang'onoang'ono kudzera. Zachidziwikire, kukula kwa via kumachepa, mtengo wofananira nawonso udzawonjezeka
Njira ziwiri zomwe takambiranazi zitha kuganiziridwa kuti kugwiritsa ntchito bolodi yocheperako ya PCB ndikothandiza kuchepetsa magawo awiri a parasitic wa via.
The mawaya chizindikiro pa bolodi PCB sayenera kusinthidwa mmene ndingathere, ndiye kuti, yesetsani ntchito vias osafunika.
Vias iyenera kukhomeredwa mu zikhomo za magetsi ndi pansi. Kufupikitsa kutsogolo pakati pa mapini ndi vias, ndibwino. Mabowo angapo amatha kubowoledwa molumikizana kuti achepetse inductance yofanana.
Ikani zibowo zozikika pafupi ndi mabowo a kusintha kwa chizindikiro kuti mupereke kuzungulira kwapafupi kwa chizindikiro. Mutha kuyika mabowo owonjezera pa bolodi la PCB.
Pakuti mkulu liwiro matabwa PCB ndi kachulukidwe mkulu, mukhoza kuganizira ntchito yaying'ono mabowo.