Daya Ma’anar asali na ramuka

Ta hanyar rami (VIA) muhimmin sashi ne na PCB mai Rarrabawa, kuma farashin ramukan hakowa galibi yana lissafin kashi 30% zuwa 40% na farashin yin katako na PCB. A taƙaice, kowane rami akan PCB ana iya kiransa ramin wucewa. Dangane da aiki, ramin za a iya raba shi gida biyu: ana amfani da ɗaya don haɗin wutar lantarki tsakanin yadudduka; Ana amfani da ɗayan don gyara na’urar ko sakawa. Dangane da tsarin, waɗannan ramukan rabe-raben sun kasu kashi uku, wato makafi ta hanyar, binne ta hanyar ta. Makafi ramuka suna kan saman da kasa saman allon da aka buga na PRINTED kuma suna da wani zurfin don haɗa farfajiyar ƙasa zuwa da’irar ciki a ƙasa. Zurfin ramukan yawanci baya wuce wani rabo (buɗewa). Ramukan da aka binne ramukan haɗin gwiwa ne a cikin ɓoyayyen ciki na allon da’irar da aka buga wanda baya kaiwa zuwa saman allon da’irar da aka buga. Nau’ikan ramukan guda biyu suna cikin layin ciki na allon da’irar, wanda tsarin gyaran ramin ya cika kafin lamination, kuma ana iya yin rufi da dama a ciki yayin samuwar ramin. Nau’i na uku, wanda ake kira ramuka, yana gudana ta cikin dukkan allon kewaye kuma ana iya amfani dashi don haɗin haɗin ciki ko azaman hawa da gano ramuka don abubuwan haɗin. Saboda ramin rami ya fi sauƙin aiwatarwa a cikin tsari, farashin ya yi ƙasa, don haka yawancin allon allon da aka buga ana amfani da shi, maimakon sauran nau’ikan biyu ta rami. Abubuwan da ke biyowa ta cikin ramuka, ba tare da bayani na musamman ba, za a ɗauke su a matsayin ramuka.

PCB ta hanyar rami na asali kuma ta hanyar gabatarwar hanyar rami

Ta fuskar zane-zane, ramin ramin ya kunshi sassa biyu ne, daya shi ne ramin da ke tsakiya, dayan kuma yankin pad da ke kusa da ramin. Girman waɗannan sassa biyu yana ƙaddara girman ramin. A bayyane yake, a cikin ƙirar babban sauri, PCB mai yawa, mai zanen koyaushe yana son ramin a matsayin ƙarami kamar yadda zai yiwu, wannan samfurin na iya barin ƙarin sararin wiring, ƙari, ƙaramin rami, ƙarfin ikon sa na parasitic shine ƙarami, ƙari dace da madaidaicin gudu. Amma raguwar girman rami a lokaci guda yana kawo hauhawar farashi, kuma ba za a iya rage girman ramin ba tare da iyaka ba, an iyakance shi ta hanyar hakowa (rami) da sanya (plating) da sauran fasaha: ƙaramin rami, tsawon lokacin da ake ɗauka don yin hakowa, zai fi sauƙi a karkace daga matsayi na tsakiya; Lokacin da zurfin ramin ya ninka diamita na rami fiye da sau 6, ba shi yiwuwa a tabbatar da suturar tagulla ta bangon ramin. Misali, idan kauri (zurfin rami) na allon PCB mai Layer 6 na al’ada shine 50Mil, to mafi ƙarancin diamita da masana’antun PCB zasu iya bayarwa shine 8Mil. Tare da haɓaka fasahar hakowa ta Laser, girman hakowa kuma na iya zama ƙarami da ƙarami. Gabaɗaya, diamita na rami bai kai ko daidai da 6Mils ba, muna kiran shi micro rami. Ana amfani da microholes sau da yawa a cikin ƙirar HDI (tsarin haɗin haɗin kai mai girma). Fasaha ta Microhole tana ba da damar bugun ramin kai tsaye a kan kushin (VIA-in-pad), wanda ke haɓaka aikin kewaye sosai kuma yana adana sararin wayoyi.

Ramin da ke kan layin watsawa shine wurin hutu na katsewar impedance, wanda zai haifar da tunanin siginar. Gabaɗaya, madaidaicin ramin ramin yana kusan kashi 12% ƙasa da na layin watsawa. Alal misali, ƙaddamar da layin watsawa na 50ohm zai ragu da 6 ohm lokacin da ya wuce ta cikin rami (ƙayyadaddun kuma yana da alaƙa da girman ramin rami da kauri farantin, amma ba cikakken raguwa ba). Duk da haka, tunanin da ya haifar da katsewar impedance ta cikin rami a haƙiƙanin ƙanƙanta ne, kuma ƙimar kwatancensa kawai :(44-50)/(44+50) =0.06. Matsalolin da ramin ke haifarwa sun fi mayar da hankali kan tasiri na iyawar parasitic da inductance.

Parasitic capacitance da inductance ta cikin rami

A parasitic ɓata capacitance wanzu a cikin rami kanta. Idan diamita na waldi juriya yankin na rami a kan kwanciya Layer ne D2, diamita na waldi kushin ne D1, da kauri daga cikin PCB jirgin ne T, da dielectric akai substrate ne ε, da parasitic capacitance ramin kusan C = 1.41εTD1/ (D2-D1).

Babban tasirin parasitic capacitance akan da’irar shine tsawaita lokacin tashin siginar da rage saurin kewaye. Alal misali, ga PCB jirgin da kauri na 50Mil, idan diamita na ta-rami kushin ne 20Mil (diamita na borehole ne 10Mils) da diamita na solder block ne 40Mil, za mu iya kimanta da parasitic capacitance na parasitic capacitance. rami ta hanyar dabara a sama: C = 1.41 × 4.4 × 0.050 × 0.020/ (0.040-0.020) = 0.31pF canjin lokacin tashin da ƙarfin ƙarfin ya haifar shine kamar haka: T10-90 = 2.2c (Z0/2) = 2.2×0.31x (50/2) = 17.05ps Daga wadannan dabi’u, ana iya ganin cewa ko da yake sakamakon tashin jinkiri da jinkirin da ke haifarwa ta hanyar parasitic capacitance na guda daya – rami ba a bayyane yake ba, idan ana amfani da ramin don sauyawa tsakanin yadudduka na lokuta da yawa, za a yi amfani da ramuka da yawa. Yi hankali a cikin ƙirar ku. A cikin ƙira mai amfani, ana iya rage ƙarfin parasitic ta hanyar ƙara nisa tsakanin rami da yankin kwanciya na jan karfe (anti-pad) ko ta hanyar rage diamita na kushin. A cikin ƙirar da’irar dijital mai sauri, inductance parasitic inductance ta rami ya fi cutarwa fiye da ƙarfin ƙarfin parasitic. Tsarin shigar sa na parasitic zai raunana gudummawar wuce gona da iri da rage tasirin tace dukkan tsarin wutar lantarki. Za mu iya kawai ƙididdige inductance parasitic inductance na ta-rami kimanin ta amfani da wadannan empirical dabara: L=5.08h [ln (4h/d) +1]

Inda L ke nufin inductance na rami, H shine tsayin rami, kuma D shine diamita na rami na tsakiya. Ana iya gani daga lissafin cewa diamita na ramin ba shi da tasiri a kan shigarwar, yayin da tsawon ramin yana da babban tasiri a cikin shigar. Har yanzu ta amfani da misalin da ke sama, ana iya ƙididdige inductance daga cikin rami kamar:

L=5.08×0.050 [ln (4×0.050/0.010) +1] = 1.015nh Idan lokacin tashin sigina ya kasance 1ns, to, daidai da girman impedance shine: XL=πL/T10-90=3.19 ω. Ba za a iya yin watsi da wannan ƙarancin ba a gaban babban ƙarfin halin yanzu. Musamman, dole ne mai wucewa mai wucewa ya ratsa ramuka biyu don haɗa layin samarwa zuwa samuwar, don haka ya ninka raunin raunin rami.

Uku, yadda ake amfani da ramin

Ta hanyar binciken da ke sama na halayen parasitic na ramuka, za mu iya ganin cewa a cikin ƙirar PCB mai sauri, ramukan da ke da sauƙi sau da yawa suna kawo mummunan tasiri ga ƙirar kewaye. Domin rage mummunan sakamako na parasitic sakamako na rami, za mu iya kokarin yin kamar haka a cikin zane:

1. Yin la’akari da farashi da ingancin sigina, an zaɓi girman rami mai ma’ana. Idan ya cancanta, yi la’akari da yin amfani da ramuka daban-daban. Misali, don wutar lantarki ko igiyoyin ƙasa, yi la’akari da amfani da manyan girma don rage rashin ƙarfi, kuma don siginar sigina, yi amfani da ƙananan ramuka. Tabbas, yayin da girman rami ya ragu, farashin da ya dace zai karu.

2. Dabaru biyu da aka tattauna a sama sun nuna cewa yin amfani da allunan PCB masu sirara suna taimakawa wajen rage sigogin parasitic guda biyu na perforations.

3. Wayoyin siginar da ke kan allon PCB bai kamata su canza yadudduka ba kamar yadda zai yiwu, wato, kar a yi amfani da ramukan da ba dole ba kamar yadda zai yiwu.

4. Ya kamata a hako fitilun wutar lantarki da ƙasa a cikin rami mafi kusa, kuma gubar tsakanin ramin da fil ɗin ya kamata ya zama ɗan gajeren lokaci. Ana iya yin la’akari da ramuka da yawa a layi daya don rage daidaitattun inductance.

5. Ana sanya wasu ramukan ƙasa kusa da ramukan shimfidar siginar domin samar da mafi kusa da siginar. Hakanan kuna iya sanya ƙarin ramuka na ƙasa da yawa akan PCB. Tabbas, kuna buƙatar zama masu sassauƙa a cikin ƙirar ku. Samfurin ramin da aka tattauna a sama shine halin da ake ciki inda ake samun gammaye a kowane Layer. Wani lokaci, zamu iya rage ko ma cire gammaye a wasu yadudduka. Musamman a yanayin yawan ramin yana da girma ƙwarai, yana iya haifar da samuwar yanke tsagewar da’ira a cikin bututun tagulla, don warware irin wannan matsalar ban da matsar da wurin ramin, mu ma muna iya duba ramin a cikin jan ƙarfe don rage girman kushin.

6. Don babban allo na PCB masu sauri tare da mafi girma, ana iya la’akari da ƙananan ramuka.