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What is the equivalent circuit of Via?

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jayasuryan

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What is the equivalent circuit of Via?
What reason, we try to reduce Vias in PCB rather than cost reduction?
 

Hello,

basically a series inductance and resistor and a parallel (branch to GND) capacitance. Depends on your circuit which elements must be considered. For a power supply bypass capacitor connected through 1 or 2 vias, mainly the unwanted inductance counts, for a high impedance circuit, the few tenths of pf could be an issue. For a transmisson line, you can design one or more vias to match the impedance, effectively eliminating the via influence.

I don't agree, that vias always should be minimized. As an example you can see arrays of via in some designs instead of one, either for higher current capacity or thermal purposes.

Regards,
Frank
 
Vias are necessary when you can fabricate more than one layer and you have a complex design.

However, vias are hard to test and repair, unlike a trace.

In high freq circuits, Vias also act as capacitors, leading to power loss.
 

We try to reduce vias only if the reduction of capacitance is predominant over the reduction of resistance.
 

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