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# How does one determine the via size for "slow" signals?

#### matrixofdynamism

Via consists of a pad along with a hole in the centre. The hole size subtracted from the pad size gives the annular ring. Vias have a whole lot of types and science behind them which matters for high speed signals so we come across terms like through hole via, buried via, blind via and then there are micro vias as well.

For signals that are "high speed" signals, the via size and type is a function of the distance from the ground and required characteristic impedance.

However, for other tracks that carry signals that do not fall into the "high speed" category, how does one determine via pad and hole size? How important is it to have one or more parallel via along signal via that are connected to GND?

Now, coming to the power supply. If a power rail needs to be connected to a different layer on the board, the only way to do that is to use one or more vias. How would one determine the via pad and holes size for this case? While signals could be categorized as high speed or low speed, I believe (please correct me if I am wrong) that when it comes to the power supply, we must always take steps to ensure power supply integrity. Therefore, the question of via size, count, placement of via and the GND vias becomes more important topic than signal vias for not "high speed" nets.

Current requirements...
Don't forget plating thickness down the via hole.

Yes, it seems current requirement is the only thing that matters here and there is a lot of option available. The same idea applies to the PCB tracks. In any case, as an answer, some specific value would be quite helpful.

Standard via size, analogue/low density digital 0.6mm land 0.3mm finished hole.
Hi density, 0.45mm land 0.2mm finished hole.

Where power is an issue I prefer to use multiple small vias, less chance of failure, compared to 1 single via...

All the above have been used on thousands of designs and millions of produced boards, the 0.6/0.3 I have used for 27+ years, the smaller one for 20 years or so...

Points: 2