A cikin aiwatar da ƙirar PCB, kafin a turawa, gabaɗaya muna tara abubuwan da muke son ƙira, kuma muna ƙididdige abubuwan da suka faru dangane da kauri, ƙasa, adadin yadudduka da sauran bayanai. Bayan lissafin, ana iya samun abun ciki gabaɗaya.

Kamar yadda ake iya gani daga wannan adadi na sama, ƙirar hanyar sadarwa mai ƙarewa guda ɗaya a sama ana sarrafa ta ta 50 ohms, don haka mutane da yawa za su tambayi dalilin da yasa ake buƙatar sarrafawa bisa ga 50 ohms maimakon 25 ohms ko 80 ohms?
Da farko, 50 ohms an zaba ta hanyar tsoho, kuma kowa da kowa a cikin masana'antu ya yarda da wannan darajar. Gabaɗaya magana, ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun dole ne a samar da su ta wata ƙungiyar da aka sani, kuma kowa yana ƙira bisa ƙa'ida.
Babban ɓangaren fasahar lantarki ya fito ne daga sojoji. Da farko dai, ana amfani da fasahar ne a aikin soja, kuma a hankali ana canja ta daga aikin soja zuwa farar hula. A farkon kwanakin aikace-aikacen microwave, a lokacin yakin duniya na biyu, zaɓin impedance ya dogara gaba ɗaya akan buƙatun amfani, kuma babu daidaitattun ƙima. Tare da ci gaban fasaha, ana buƙatar ba da ƙa'idodin impedance don daidaita daidaito tsakanin tattalin arziki da dacewa.

A {asar Amirka, ana haɗa magudanar ruwa da aka fi amfani da su ta hanyar sanduna da bututun ruwa. 51.5 ohms yana da yawa, amma adaftan da masu canzawa da aka gani da amfani da su sune 50-51.5 ohms; an warware wannan ga sojojin hadin gwiwa da na ruwa. Matsala, an kafa wata kungiya mai suna JAN (daga baya kungiyar DESC), wadda MIL ta kirkira ta musamman, kuma a karshe aka zabi 50 ohms bayan an yi la’akari sosai, sannan aka kera catheter masu alaka da su aka canza su zuwa igiyoyi daban-daban. Matsayi.

A wannan lokacin, ma'aunin Turai ya kasance 60 ohms. Ba da daɗewa ba, a ƙarƙashin rinjayar manyan kamfanoni kamar Hewlett-Packard, Turawa kuma an tilasta musu su canza, don haka 50 ohms ƙarshe ya zama misali a cikin masana'antu. Ya zama al'ada, kuma PCB da aka haɗa da igiyoyi daban-daban ana buƙatar ƙarshe don biyan ma'aunin 50 ohm impedance don dacewa da impedance.

Abu na biyu, ƙaddamar da ƙa'idodi na gaba ɗaya za a dogara ne akan cikakkun la'akari da tsarin samarwa na PCB da aikin ƙira da yuwuwar.

Daga hangen nesa na samarwa da fasaha na sarrafa PCB, da kuma la'akari da kayan aiki na yawancin masana'antun PCB da ke wanzu, yana da sauƙi don samar da PCBs tare da 50 ohm impedance. Daga tsarin lissafin impedance, ana iya ganin cewa ƙananan ƙarancin yana buƙatar faɗin layi mai faɗi da matsakaici na bakin ciki ko mafi girman dielectric akai-akai, wanda ya fi wuya a hadu da katako mai girma na yanzu a sararin samaniya; maɗaukakiyar rashin ƙarfi yana buƙatar layi mai zurfi Fadi da kauri kafofin watsa labarai ko ƙananan dielectric akai-akai ba su da amfani ga murkushe EMI da crosstalk. A lokaci guda kuma, amincin aiki don allunan multilayer kuma daga yanayin samar da taro zai zama mara kyau. Sarrafa 50 ohm impedance. A ƙarƙashin yanayin amfani da allunan gama gari (FR4, da sauransu) da allunan mahimmanci na gama gari, samar da samfuran kauri na gama gari (kamar 1mm, 1.2mm, da sauransu). Za a iya tsara nisa na gama gari (mil 4 ~ 10). Ma'aikatar ta dace sosai don sarrafawa, kuma kayan aikin da ake buƙata don sarrafa shi ba su da yawa.

Daga hangen nesa na ƙirar PCB, 50 ohms kuma an zaɓi bayan cikakken la'akari. Daga aikin burbushin PCB, ƙarancin impedance gabaɗaya ya fi kyau. Don layin watsa mai fadin layin da aka bayar, mafi kusancin nesa da jirgin, za a rage madaidaicin EMI, sannan kuma za a rage yawan magana. Koyaya, daga mahangar cikakken hanyar siginar, ɗayan mahimman abubuwan yana buƙatar la'akari, wato, ikon tuƙi na guntu. A cikin farkon kwanakin, yawancin kwakwalwan kwamfuta ba za su iya fitar da layin watsawa tare da impedance kasa da 50 ohms ba, kuma layin watsawa tare da mafi girman impedance ba su da sauƙin aiwatarwa. Don haka ana amfani da impedance 50 ohm azaman sulhu.

Source: Ana canja wurin wannan labarin daga Intanet, kuma haƙƙin mallaka na ainihin marubucin ne.