Re: [SI-LIST] : via capacitance

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From: Ritchey Lee (leeritchey@earthlink.net)
Date: Mon Apr 10 2000 - 09:15:36 PDT


I have done many experiments to determine the capacitance value of vias. A 13 mil diameter via, 100 mils long has approximately .3 pF of capacitance. Your traces will average about 3 pF per inch of
length. The small value of the via capacitance will not be detectable at edge rates slower than 100 pSEc.

Lee

Sunil Kumar wrote:

> Dear all SI experts.
>
> I am using a multilayer board having the following stack-up:
>
> LAYER1 TOP LAYER (CONDUCTOR)
> LAYER2 GND
> LAYER3 CONDUCTOR
> LAYER4 CONDUCTOR
> LAYER5 VCC
> LAYER6 GND
> LAYER7 CONDUCTOR
> LAYER8 CONDUCTOR
> LAYER9 GND
> LAYER10 BOTTOM LAYER (CONDUCTOR)
>
> A signal trace is going from layer7 to layer8. A through-hole via is used.
> The via is having pads on layers 1,7,8,10. There are antipads on the power
> planes. Is there any formula/tools to calculate the exact capacitance of
> the via?? How can I measure it in the board??
>
> Sunil Kumar
> Research Engineer
> C-DOT
> INDIA
>
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