What via size is correct

[kvresto]

Hi Everyone, just a quick question about via sizes. I have a 3.3V power trace snaking its way around the PCB, using top and bottom layers. I'm using via sizes of 0.66mm diameter, and 0.33mm hole size, and I want to know is it advisable to use this size via to connect a 1mm power traces across the top and bottom layers, there a few of these connections?
What is the correct design practice here? current capacity? impedance? other?
The pic shows a 0.65mm trace.

thanks
kvresto

[DerekG]

I have a 3.3V power trace snaking its way around the PCB, using top and bottom layers.

Power planes (copper flood areas) are always good practice, especially for the earth.

Having said that, often you can "snake your way around in a circle" to that the power track is fed current from both ends. I do this very regularly.

[kvresto]

great, thanks

[Jeroen3]

Use two 0.5 mm via's.

[fanOfeeDIY]

I am not a PCB designer so I only could comment the size commonly saw and used when I was working at an Electronic company which  the PCB designed by others colleagues.

For regular signal trace, track width was 0.2mm, via diameter was 0.6mm, via drill was 0.3mm.
For power rail, track width was 1mm, via diameter was 0.6mm, via drill was 0.3mm and often time multiple vias were used to connect the rails.

I have no idea of math behind how the size was chosen, but it seemed to be working OK.


Of course real analog, RF, high frequency digital circuit, and etc, were different.

[crispytato]

Check out Saturn PCB toolkit. It allows you to calculate, to excruciating level of detail, the properties of vias/traces etc. You just need to decide on an acceptable level of voltage drop, put in your pcb properties, and you can get the minimum size of via that would be acceptable.

It's free, and helps me a heap when I'm worried that a power trace might be marginal (they seldom are, but I like to design with a large margin of error, rather than cutting it close to the limit!)

[kvresto]

Great app, also found one of Daves older videos, EEVBlog #543 - PCB VIA Current Investigation. All the information you could ask for.