Feem ntau hais lus, cov yam ntxwv uas cuam tshuam rau tus yam ntxwv impedance ntawm PCB yog: dielectric thickness H, tooj liab thickness T, kab dav W, kab sib nrug, dielectric tas li Er ntawm cov khoom xaiv rau pawg, thiab thickness ntawm lub qhov ncauj qhov ntswg.

Feem ntau, qhov ntau dua qhov dielectric thickness thiab kab sib nrug, qhov ntau dua tus nqi impedance; qhov ntau dua qhov dielectric tas li, tooj liab thickness, kab dav, thiab solder mask thickness, qhov me me impedance tus nqi.

Thawj qhov: nruab nrab tuab, nce qhov nruab nrab tuab tuaj yeem ua rau qhov impedance, thiab txo qhov nruab nrab thickness tuaj yeem txo qhov impedance; txawv prepregs muaj cov kua nplaum sib txawv thiab thicknesses. Lub thickness tom qab nias muaj feem xyuam rau lub flatness ntawm cov xovxwm thiab cov txheej txheem ntawm nias phaj; rau txhua hom phaj siv, nws yog ib qho tsim nyog kom tau txais cov thickness ntawm cov txheej txheem xov xwm uas tuaj yeem tsim tau, uas yog qhov tsim nyog rau kev tsim kev suav, thiab kev tsim engineering, nias phaj tswj, tuaj yeem ua siab ntev yog tus yuam sij rau kev tshaj tawm thickness tswj.

Qhov thib ob: kab dav, ua kom txoj kab dav tuaj yeem txo qhov impedance, txo txoj kab dav tuaj yeem ua rau qhov impedance. Kev tswj ntawm txoj kab dav yuav tsum nyob rau hauv lub siab ntev ntawm +/- 10% kom ua tiav qhov kev tswj hwm impedance. Qhov sib txawv ntawm cov kab teeb liab cuam tshuam rau tag nrho cov ntawv xeem waveform. Nws ib leeg-point impedance yog siab, ua rau tag nrho cov waveform tsis sib npaug, thiab cov kab impedance tsis pub ua Kab, qhov sib txawv tsis tuaj yeem tshaj 10%. Txoj kab dav feem ntau yog tswj los ntawm etching tswj. Txhawm rau kom ntseeg tau cov kab dav, raws li qhov etching sab etching tus nqi, lub teeb teeb duab yuam kev, thiab cov qauv hloov pauv, cov txheej txheem zaj duab xis yog them rau cov txheej txheem kom tau raws li qhov xav tau ntawm kab dav.

Qhov thib peb: tooj liab thickness, txo cov kab thickness tuaj yeem ua rau cov impedance, nce cov kab thickness tuaj yeem txo qhov impedance; cov kab tuab tuaj yeem tswj tau los ntawm cov qauv plating lossis xaiv qhov sib thooj thickness ntawm cov khoom siv tooj liab ntawv ci. Kev tswj ntawm tooj liab thickness yuav tsum tau sib xws. Ib qho shunt block yog ntxiv rau lub rooj tsavxwm ntawm cov xov hlau nyias thiab cov xov hlau sib cais kom sib npaug ntawm qhov tam sim no los tiv thaiv qhov tsis sib xws ntawm tooj liab tuab ntawm cov hlau thiab cuam tshuam rau qhov tsis sib xws ntawm tooj liab ntawm cs thiab ss nto. Nws yog ib qho tsim nyog yuav tau hla lub rooj tsavxwm kom ua tiav lub hom phiaj ntawm cov hlau tsis sib xws ntawm ob sab.

Qhov thib plaub: dielectric tas li, nce qhov dielectric tas li tuaj yeem txo qhov impedance, txo qhov dielectric tas li tuaj yeem ua rau kom qhov impedance, qhov dielectric tas li yog tswj los ntawm cov khoom siv. Lub dielectric qhov tsis tu ncua ntawm cov phaj sib txawv yog txawv, uas muaj feem xyuam rau cov khoom siv resin: qhov dielectric tas li ntawm FR4 phaj yog 3.9-4.5, uas yuav txo qis nrog qhov nce ntawm kev siv ntau zaus, thiab dielectric tas li ntawm PTFE phaj yog 2.2. - Kom tau txais cov teeb liab siab kis tau tus mob ntawm 3.9 yuav tsum muaj tus nqi siab impedance, uas yuav tsum muaj qhov tsis tshua muaj dielectric.

Qhov thib tsib: lub thickness ntawm lub qhov ncauj qhov ntswg. Kev luam daim npog ntsej muag yuav txo qhov tsis kam ntawm txheej txheej. Nyob rau hauv ib txwm muaj xwm txheej, luam ntawv ib daim npog ntsej muag tuaj yeem txo qhov kev poob ib zaug los ntawm 2 ohms, thiab tuaj yeem ua rau qhov sib txawv poob los ntawm 8 ohms. Kev luam ob zaug tus nqi poob yog ob zaug ntawm ib qho dhau. Thaum luam ntawv ntau tshaj peb zaug, tus nqi impedance yuav tsis hloov.