Vim li cas PCB boards xav tau impedance

Dab tsi yog impedance

Nyob rau hauv circuits nrog tsis kam, inductance, thiab capacitance, qhov tsis kam mus rau alternating tam sim no hu ua impedance. Impedance feem ntau yog sawv cev los ntawm Z, uas yog tus lej nyuaj. Qhov tiag tiag yog hu ua tsis kam, thiab qhov xav txog yog hu ua reactance. Lub blocking nyhuv ntawm capacitance ntawm alternating tam sim no nyob rau hauv lub Circuit Court yog hu ua capacitive reactance, thiab lub blocking nyhuv ntawm inductance ntawm alternating tam sim no nyob rau hauv Circuit Court yog hu ua rau inductive reactance, lub blocking nyhuv ntawm capacitance thiab inductance ntawm alternating tam sim no nyob rau hauv lub Circuit Court yog collectively hu ua. reactance. Qhov ntsuas ntawm impedance yog ohms.

Hom impedance

(1) Cov yam ntxwv impedance

Hauv cov khoom siv hluav taws xob xws li khoos phis tawj thiab kev sib txuas lus wireless, lub zog xa mus rau hauv Circuit Court ntawm PCB yog lub teeb liab square yoj (hu ua mem tes) tsim los ntawm qhov hluav taws xob thiab lub sijhawm, thiab qhov kev tawm tsam uas nws ntsib yog hu ua tus yam ntxwv impedance.

(2) Txawv impedance

Kev tsav tsheb kawg inputs ob lub teeb liab zoo tib yam waveforms nrog opposite polarities, uas feem ntau kis tau los ntawm ob kab sib txawv, thiab ob lub teeb liab sib txawv raug rho tawm ntawm qhov kawg tau txais. Qhov sib txawv impedance yog qhov impedance Zdiff ntawm ob lub xov hlau.

(3) Odd-hom impedance

Lub impedance Zoo ntawm ib kab rau hauv av hauv ob kab, tus nqi impedance ntawm ob kab yog tib yam.

(4) Txawm hom impedance

Kev tsav tsheb kawg nkag mus rau ob lub teeb liab zoo tib yam waveforms nrog tib lub polarity, thiab lub impedance Zcom thaum ob kab txuas ua ke.

(5) Hom hom impedance

Lub impedance Zoe ntawm ib kab rau hauv av nyob rau hauv ob kab, tus nqi impedance ntawm ob kab yog tib yam, feem ntau loj dua qhov khib hom impedance.

Vim li cas PCB boards xav tau impedance?

Lub impedance ntawm pcb Circuit Court board yog hais txog qhov tsis kam ntawm qhov tsis kam thiab reactance, uas cuam tshuam rau qhov hloov pauv tam sim no. Hauv kev tsim cov pcb Circuit Court boards, kev ua haujlwm impedance yog qhov tseem ceeb. Cov laj thawj yog raws li nram no:

1. Lub PCB Circuit Court (hauv qab ntawm lub rooj tsavxwm) yuav tsum xav txog kev teeb tsa ntawm cov khoom siv hluav taws xob, thiab xav txog cov khoom siv hluav taws xob thiab cov teeb liab kis tau tus mob tom qab ntsaws, yog li qhov qis impedance, qhov zoo dua.

2. Thaum lub sij hawm tsim cov txheej txheem, PCB Circuit Court board yuav tsum mus los ntawm cov txheej txheem ntawm tooj liab sinking, electroplating tin (los yog electroless plating, los yog thermal spray tin), connector soldering thiab lwm yam txheej txheem, thiab cov ntaub ntawv siv nyob rau hauv cov kev sib txuas yuav tsum xyuas kom meej tias. lub resistivity yog tsawg los xyuas kom meej tias tag nrho impedance ntawm lub rooj tsavxwm Circuit Court yog tsawg kom tau raws li cov khoom yuav tsum tau zoo thiab muaj peev xwm ua hauj lwm ib txwm.

3. Lub tinning ntawm lub PCB Circuit Court board yog feem ntau muaj teeb meem nyob rau hauv zus tau tej cov tag nrho Circuit Court board, thiab nws yog qhov tseem ceeb txuas uas cuam tshuam rau impedance. Qhov loj tshaj ntawm electroless tin plating txheej yog yooj yim discoloration (yooj yim rau oxidize los yog deliquescence) thiab tsis zoo solderability, uas yuav ua rau lub Circuit Court board nyuaj rau solder, thiab impedance yuav siab dhau heev lawm, ua rau tsis zoo hluav taws xob conductivity los yog tsis ruaj tsis khov kev ua tau zoo. tag nrho lub rooj tsavxwm.

4. Yuav muaj ntau yam teeb liab kis tau tus mob nyob rau hauv lub conductors nyob rau hauv lub PCB Circuit Court board. Txhawm rau txhim kho tus nqi sib kis, qhov zaus yuav tsum tau nce ntxiv. Yog hais tias cov kab nws tus kheej txawv vim yog yam xws li etching, pawg tuab, thiab hlau dav, tus nqi impedance yuav hloov. , yog li ntawd lub teeb liab yog distorted thiab kev ua tau zoo ntawm lub Circuit Court board yog degraded, yog li nws yog tsim nyog los tswj tus nqi impedance nyob rau hauv ib tug tej yam ntau yam.

Lub ntsiab lus ntawm impedance rau PCB Circuit Board

Rau kev lag luam hluav taws xob, raws li kev tshawb fawb kev lag luam, feem ntau tsis muaj zog ntawm electroless tin plating yog ib qho yooj yim discoloration (ob qho tib si yooj yim rau oxidize los yog deliquescence), tsis zoo solderability, uas ua rau nyuaj soldering, thiab siab impedance, uas ua rau tsis zoo hluav taws xob conductivity los yog kev ua haujlwm tsis ruaj khov ntawm tag nrho pawg thawj coj saib. , Ib qho yooj yim kom loj hlob tin whiskers, ua rau luv luv Circuit Court ntawm PCB thiab txawm hlawv los yog hluav taws.

Tom qab ntawd, thaum tag nrho cov kev lag luam kev lag luam tsim tawm mus rau ib qho twg, ntau tus neeg koom tom qab nyiam sib luam. Qhov tseeb, ntau lub tuam txhab lawv tus kheej tsis muaj peev xwm los tsim lossis pib tsim kho tshiab. Yog li ntawd, ntau yam khoom thiab lawv cov neeg siv khoom siv hluav taws xob (cov khoom siv hluav taws xob) tau tsim. Qhov laj thawj tseem ceeb ntawm kev ua haujlwm tsis zoo yog qhov teeb meem impedance, vim hais tias thaum siv cov tshuab electroless tin plating tsis tsim nyog, cov tin plated ntawm PCB yog qhov tseeb Nws tsis yog cov hlau ntshiab (lossis cov hlau ntshiab), tab sis cov khoom siv ntawm cov tin ( uas yog, nws tsis yog hlau kiag li, tab sis ib tug hlau compound, oxide los yog halide, ntau ncaj qha ib yam khoom uas tsis yog-metallic) los yog tin A sib tov ntawm compound thiab tin hlau ntsiab, tab sis nws yog ib qho nyuaj rau nrhiav tau ntawm qhov muag liab qab. ...

Vim tias lub ntsiab ntawm lub rooj tsav xwm PCB Circuit Court yog tooj liab, txheej tinned yog nyob rau ntawm cov pob qij txha ntawm cov ntawv ci tooj liab, thiab cov khoom siv hluav taws xob yog welded rau ntawm tinned txheej los ntawm solder paste (los yog solder hlau). Nyob rau hauv qhov tseeb, lub solder paste yog melting. Lub xeev soldered ntawm cov khoom siv hluav taws xob thiab cov tin txheej yog hlau tin (uas yog, cov khoom siv hlau nrog cov hluav taws xob zoo), yog li nws tuaj yeem qhia luv luv tias cov khoom siv hluav taws xob txuas nrog cov ntawv ci tooj liab hauv qab ntawm PCB. los ntawm cov tin txheej, yog li cov tin txheej Cov purity ntawm cov cuab yeej thiab nws impedance yog qhov tseem ceeb; tab sis ua ntej cov khoom siv hluav taws xob txuas nrog, thaum peb ncaj qha siv lub ntsuas ntsuas los ntsuas qhov impedance, qhov tseeb, ob qhov kawg ntawm qhov ntsuas ntsuas (lossis kuaj cov hlau lead) kuj raug hu los ntawm cov ntawv ci tooj liab nyob rau hauv qab ntawm PCB. Lub tin plating txheej yog txuas nrog cov ntawv ci tooj liab rau hauv qab ntawm PCB los txuas rau tam sim no. Yog li ntawd, tin plating txheej yog tus yuam sij, tus yuam sij rau cuam tshuam rau impedance thiab tus yuam sij cuam tshuam rau kev ua haujlwm ntawm tag nrho PCB, thiab tus yuam sij uas yooj yim yuav tsis quav ntsej.

Raws li peb txhua tus paub, tshwj tsis yog cov khoom siv hlau, nws cov tebchaw yog cov khoom siv hluav taws xob tsis zoo lossis txawm tias tsis muaj hluav taws xob (qhov no kuj yog tus yuam sij rau kev muaj peev xwm ntawm kev xa tawm lossis kev xa tawm hauv Circuit Court), yog li muaj cov khoom siv hluav taws xob zoo li no. tab sis tsis yog conductive tin nyob rau hauv tin plating txheej. Thaum siv los yog sib tov, nws npaj txhij-rau-siv resistivity los yog cov resistivity thiab nws cov impedance sib raug zoo tom qab electrolytic cov tshuaj tiv thaiv vim oxidation thiab noo noo nyob rau hauv lub neej yav tom ntej yog heev siab (muaj txaus cuam tshuam rau theem los yog teeb liab kis tau tus mob nyob rau hauv cov circuits,) thiab nws cov yam ntxwv Impedances kuj tsis sib xws. Yog li nws yuav cuam tshuam rau kev ua haujlwm ntawm lub rooj tsav xwm Circuit Court thiab tag nrho lub tshuab.

Yog li ntawd, raws li qhov tam sim no kev lag luam tshwm sim muaj kev txhawj xeeb, cov khoom siv thiab cov khoom ntawm cov txheej hauv qab ntawm PCB yog cov laj thawj tseem ceeb thiab feem ntau ncaj qha uas cuam tshuam rau cov yam ntxwv impedance ntawm tag nrho PCB, tab sis kuj yog vim qhov tseeb tias. nws muaj cov nyhuv ntawm kev laus nrog cov txheej thiab electrolysis thaum raug cov dej noo. Variation, yog li qhov teeb meem cuam tshuam ntawm nws impedance ua ntau insidious thiab sib txawv. Cov laj thawj tseem ceeb rau nws qhov zais cia yog: thawj zaug, nws tsis tuaj yeem pom los ntawm qhov muag liab qab (suav nrog nws cov kev hloov pauv), thiab qhov thib ob, nws tsis tuaj yeem ntsuas tsis tu ncua vim tias nws muaj qhov sib txawv nrog lub sijhawm thiab ib puag ncig cov av noo hloov pauv, yog li nws ib txwm yooj yim los ua. tsis quav ntsej.