In high-ceev HDI PCB tsim, ntawm kev tsim yog ib qho tseem ceeb. Nws muaj ib lub qhov, ib tug ncoo cheeb tsam nyob ib ncig ntawm lub qhov, thiab ib tug cais cheeb tsam ntawm lub POWER txheej, uas feem ntau muab faib ua peb hom: qhov muag tsis pom qhov, faus qhov thiab los ntawm lub qhov. Hauv cov txheej txheem tsim PCB, los ntawm kev txheeb xyuas cov kab mob parasitic capacitance thiab parasitic inductance ntawm lub vias, qee qhov kev ceev faj hauv kev tsim ntawm high-speed PCB vias tau sau tseg.

Tam sim no, high-speed PCB tsim tau dav siv hauv kev sib txuas lus, khoos phis tawj, duab thiab duab ua thiab lwm yam haujlwm. Tag nrho cov khoom siv hluav taws xob muaj txiaj ntsig ntxiv cov khoom siv hluav taws xob tau ua raws li cov yam ntxwv xws li kev siv hluav taws xob tsawg, hluav taws xob hluav taws xob tsawg, kev ntseeg siab, miniaturization, thiab lub teeb yuag. Yuav kom ua tiav cov hom phiaj saum toj no, ntawm kev tsim qauv yog qhov tseem ceeb hauv kev tsim PCB high-speed.

1. Via
Via yog qhov tseem ceeb hauv kev tsim ntau txheej PCB. A via yog tsim los ntawm peb ntu, ib qho yog lub qhov; lwm qhov yog lub ncoo thaj tsam ib ncig ntawm lub qhov; thiab qhov thib peb yog thaj chaw cais ntawm POWER txheej. Cov txheej txheem ntawm lub qhov ntawm lub qhov yog phaj ib txheej ntawm cov hlau ntawm lub cylindrical nto ntawm lub qhov phab ntsa ntawm lub qhov ntawm lub qhov los ntawm cov tshuaj deposition mus cuag cov tooj liab ntawv ci uas yuav tsum tau kev cob cog rua rau nruab nrab cov khaubncaws sab nraud povtseg, thiab sab sauv thiab sab sab. qhov ntawm lub qhov yog ua rau hauv cov pawm zoo tib yam Cov duab tuaj yeem txuas ncaj qha nrog cov kab ntawm sab sauv thiab sab qis, lossis tsis txuas nrog. Vias tuaj yeem ua lub luag haujlwm ntawm kev sib txuas hluav taws xob, kho lossis tso cov khoom siv.

Vias feem ntau muab faib ua peb pawg: qhov muag qhov muag, qhov faus thiab hauv qhov.

Qhov qhov muag tsis pom kev nyob rau saum thiab hauv qab ntawm cov ntawv luam tawm Circuit Board thiab muaj qhov tob. Lawv yog siv los txuas cov kab saum npoo thiab cov kab hauv qab. Qhov tob ntawm lub qhov thiab txoj kab uas hla ntawm lub qhov feem ntau tsis tshaj ib qho piv txwv.

Lub qhov faus yog hais txog qhov sib txuas nyob rau hauv txheej txheej ntawm lub rooj tsav xwm luam tawm, uas tsis txuas mus rau qhov chaw ntawm lub rooj tsav xwm Circuit Court.

Qhov muag tsis pom vias thiab faus vias yog ob qho tib si nyob rau hauv cov txheej txheem sab hauv ntawm lub rooj tsav xwm Circuit Court, uas yog ua tiav los ntawm qhov kev tsim cov txheej txheem ua ntej lamination, thiab ob peb txheej sab hauv tuaj yeem sib tshooj thaum tsim cov vias.

Los ntawm qhov, uas dhau los ntawm tag nrho lub rooj tsav xwm hauv Circuit Court, tuaj yeem siv rau kev sib txuas sab hauv lossis ua ib feem ntawm qhov chaw teeb tsa. Txij li los ntawm qhov yog yooj yim dua rau kev siv hauv cov txheej txheem thiab tus nqi qis, feem ntau cov ntawv luam tawm Circuit Board siv los ntawm qhov.

2. Parasitic capacitance ntawm vias
Lub viav vias nws tus kheej muaj cov kab mob parasitic rau hauv av. Yog hais tias txoj kab uas hla ntawm lub qhov sib cais ntawm lub hauv av txheej ntawm lub viav vias yog D2, txoj kab uas hla ntawm lub ncoo yog D1, lub thickness ntawm lub PCB yog T, thiab lub dielectric tsis tu ncua ntawm lub board substrate yog ε, ces tus parasitic capacitance viav vias zoo ib yam li:

C = 1.41εTD1/(D2-D1)

Cov txiaj ntsig tseem ceeb ntawm cov kab mob parasitic capacitance ntawm lub qhov ntawm lub voj voog yog kom ntev lub sij hawm nce ntawm lub teeb liab thiab txo qhov ceev ntawm Circuit Court. Qhov me me ntawm tus nqi capacitance, qhov ua rau me me.

3. Parasitic inductance ntawm vias
Lub vias nws tus kheej muaj parasitic inductance. Nyob rau hauv kev tsim ntawm high-ceev digital circuits, qhov teeb meem tshwm sim los ntawm cov kab mob parasitic inductance ntawm cov viav vias feem ntau ntau dua li qhov cuam tshuam ntawm cov kab mob parasitic capacitance. Parasitic series inductance ntawm lub viav vias yuav ua rau tsis muaj zog ntawm kev ua haujlwm ntawm lub bypass capacitor thiab tsis muaj zog lim dej ntawm tag nrho lub zog. Yog hais tias L yog hais txog qhov inductance ntawm lub via, h yog qhov ntev ntawm lub vias, thiab d yog txoj kab uas hla ntawm qhov chaw nruab nrab, cov kab mob parasitic inductance ntawm lub via yog zoo ib yam li:

L = 5.08h［ln(4h/d) 1］

Nws tuaj yeem pom los ntawm cov qauv uas txoj kab uas hla ntawm lub viav vias muaj qhov cuam tshuam me me rau ntawm qhov inductance, thiab qhov ntev ntawm cov viav vias muaj qhov cuam tshuam loj tshaj plaws ntawm qhov inductance.

4. Tsis yog los ntawm kev siv tshuab
Tsis-los ntawm vias muaj xws li dig muag vias thiab faus vias.

Nyob rau hauv tsis yog los ntawm kev siv tshuab, daim ntawv thov ntawm qhov muag tsis pom vias thiab faus vias tuaj yeem txo qhov loj thiab zoo ntawm PCB, txo cov txheej txheej, txhim kho electromagnetic compatibility, nce cov yam ntxwv ntawm cov khoom siv hluav taws xob, txo cov nqi, thiab tseem ua rau tus tsim ua hauj lwm ntau yooj yim thiab ceev. Hauv kev tsim PCB ib txwm siv thiab ua tiav, los ntawm qhov tuaj yeem nqa ntau yam teeb meem. Ua ntej, lawv nyob ib tug loj npaum li cas ntawm kev qhov chaw, thiab tib ob, ib tug loj tus naj npawb ntawm los ntawm qhov yog densely tau ntim rau hauv ib qhov chaw, uas kuj tsim ib tug lossis loj lub chaw khuam siab rau lub puab txheej thaiv ntawm lub multilayer PCB. Cov no los ntawm qhov nyob ntawm qhov chaw uas xav tau rau kev xaim, thiab lawv tau dhau los ntawm cov khoom siv hluav taws xob thiab hauv av. Qhov saum npoo ntawm cov hlau txheej tseem yuav rhuav tshem cov yam ntxwv impedance ntawm lub zog hauv av hlau txheej thiab ua rau lub zog hauv av hlau txheej tsis zoo. Thiab cov txheej txheem kev siv tshuab ua haujlwm ntawm drilling yuav yog 20 npaug ntawm kev ua haujlwm ntawm cov tshuab tsis yog los ntawm lub qhov.

Hauv PCB tsim, txawm hais tias qhov loj ntawm cov ntaub qhwv thiab vias tau maj mam txo qis, yog tias lub thickness ntawm lub rooj tsavxwm txheej tsis yog proportionally txo, qhov nam piv ntawm qhov los ntawm qhov yuav nce, thiab qhov nce ntawm qhov sib piv ntawm lub qhov yuav txo tau. kev ntseeg tau. Nrog rau kev loj hlob ntawm advanced laser drilling tshuab thiab plasma qhuav etching tshuab, nws muaj peev xwm mus thov cov uas tsis yog nkag mus rau qhov me me dig muag qhov thiab me me faus qhov. Yog hais tias txoj kab uas hla ntawm cov uas tsis yog-nkaum vias yog 0.3 hli, cov kab mob parasitic yuav yog li ntawm 1/10 ntawm cov thawj cov pa qhov, uas txhim kho kev ntseeg siab ntawm PCB.

Vim tias tsis yog los ntawm kev siv thev naus laus zis, muaj ob peb lub vias loj ntawm PCB, uas tuaj yeem muab ntau qhov chaw rau cov kab. Qhov chaw seem tuaj yeem siv rau thaj chaw loj tiv thaiv lub hom phiaj txhawm rau txhim kho EMI / RFI kev ua haujlwm. Nyob rau tib lub sijhawm, qhov chaw seem ntxiv tuaj yeem siv rau txheej txheej sab hauv los tiv thaiv cov cuab yeej thiab cov cables tseem ceeb, kom nws muaj qhov zoo tshaj plaws hluav taws xob. Kev siv cov khoom siv tsis yog vias ua rau nws yooj yim dua rau kiv cua tawm cov pins, ua kom yooj yim rau txoj hauv kev siab ceev tus pin cov cuab yeej (xws li BGA ntim cov khoom), ua kom luv cov hlua ntev, thiab ua tau raws li lub sijhawm ntawm kev kub ceev circuits. .

5. Ntawm kev xaiv hauv PCB zoo tib yam
Hauv kev tsim PCB zoo tib yam, cov kab mob parasitic capacitance thiab parasitic inductance ntawm lub viav vias muaj kev cuam tshuam me ntsis ntawm PCB tsim. Rau 1-4 txheej PCB tsim, 0.36mm / 0.61mm / 1.02mm (drilled qhov / ncoo / POWER cais cheeb tsam feem ntau xaiv) ) Vias zoo dua. Rau cov kab teeb liab uas yuav tsum tau tshwj xeeb (xws li cov kab hluav taws xob, kab hauv av, kab moos, thiab lwm yam), 0.41mm / 0.81mm / 1.32mm vias tuaj yeem siv, lossis vias ntawm lwm qhov ntau thiab tsawg tuaj yeem xaiv raws li qhov xwm txheej tiag tiag.

6. Ntawm kev tsim hauv high-speed PCB
Los ntawm kev soj ntsuam saum toj no ntawm cov yam ntxwv parasitic ntawm vias, peb tuaj yeem pom tau tias nyob rau hauv high-speed PCB tsim, zoo li yooj yim vias feem ntau coj cov teeb meem tsis zoo rau lub voj voog tsim. Txhawm rau txo qhov tsis zoo tshwm sim los ntawm cov kab mob parasitic ntawm lub vias, cov hauv qab no tuaj yeem ua tiav hauv kev tsim:

(1) Xaiv qhov tsim nyog ntawm qhov loj me. Rau ntau txheej txheej dav dav-density PCB tsim, nws yog qhov zoo dua los siv 0.25mm / 0.51mm / 0.91mm (drilled qhov / pads / POWER cheeb tsam cais tawm) vias; rau qee qhov siab ceev PCBs, 0.20mm / 0.46 kuj tseem siv tau mm / 0.86mm vias, koj tuaj yeem sim tsis dhau vias; rau lub zog los yog hauv av vias, koj tuaj yeem txiav txim siab siv qhov loj dua los txo impedance;

(2) Qhov loj dua ntawm POWER kev cais thaj chaw, qhov zoo dua, txiav txim siab ntawm qhov ceev ntawm PCB, feem ntau D1 = D2 0.41;

(3) Sim tsis txhob hloov cov khaubncaws sab nraud povtseg ntawm cov cim qhia ntawm PCB, uas txhais tau tias kom txo qis ntawm vias;

(4) Kev siv lub thinner PCB yog qhov tsim nyog los txo cov kab mob parasitic ntawm ob txoj kab;

(5) Lub hwj chim thiab hauv av pins yuav tsum tau ua los ntawm qhov nyob ze. Qhov luv luv ntawm cov hlau lead ntawm lub qhov ntawm lub qhov thiab tus pin, qhov zoo dua, vim tias lawv yuav nce qhov inductance. Nyob rau tib lub sij hawm, lub hwj chim thiab av leads yuav tsum tuab li sai tau kom txo impedance;

(6) Muab qee qhov av nyob ze ntawm lub vias ntawm lub teeb liab txheej los muab lub voj luv luv rau lub teeb liab.

Tau kawg, cov teeb meem tshwj xeeb yuav tsum tau txheeb xyuas kom meej thaum tsim. Xav txog ob qho tib si tus nqi thiab cov teeb liab zoo meej, hauv kev tsim PCB high-ceev, cov neeg tsim qauv ib txwm cia siab tias qhov me me ntawm lub qhov yog, qhov zoo dua, kom ntau qhov chaw xaim tuaj yeem tso rau ntawm lub rooj tsavxwm. Tsis tas li ntawd, qhov me me ntawm lub qhov, nws tus kheej Qhov me me ntawm cov kab mob parasitic capacitance, qhov tsim nyog rau high-speed circuits. Nyob rau hauv high-density PCB tsim, kev siv uas tsis yog los ntawm vias thiab txo qhov luaj li cas ntawm vias kuj ua rau ib tug nce nyob rau hauv tus nqi, thiab qhov luaj li cas ntawm vias yuav txo tau indefinitely. Nws raug cuam tshuam los ntawm PCB cov tuam txhab cov txheej txheem drilling thiab electroplating. Kev txwv tsis pub yuav tsum tau muab kev txiav txim siab sib npaug hauv kev tsim cov PCBs ceev.