Arbitrary shape trace resistance

I’m trying to calculate the resistance of some power traces and am having problems finding what I need. I’m well aware of the standard trace resistance calculators, but they only handle rectangular traces.

I assume that there are tools out there that can take an arbitrarily shaped trace and give you the resistance between two ends but I’m not having much luck finding them. Any ideas? I don’t care about the interface and it doesn’t even have to be a traditional PCB design package - it might even be easier for me if it accepts a CAD model. Bonus points if it lets me model something like a silver tab soldered onto a copper trace…

Thanks!

Anyone? I find it hard to believe that there is no software that I can use to find the resistance of a trace on a pcb…

I think some high-end CAD packages (such as Altium) will do that, but the actual resistance will always vary due to manufacturing tolerances (mainly the thickness of the copper plating). Most of the time a “back of the envelope” calculation would be sufficient anyway…

MichaelN:
I think some high-end CAD packages (such as Altium) will do that, but the actual resistance will always vary due to manufacturing tolerances (mainly the thickness of the copper plating). Most of the time a “back of the envelope” calculation would be sufficient anyway…

I do not believe Altium has this ability. It certainly didn't when I asked them about it a few years back, and I haven't seen it in any release notes since that time.

I have never seen a program with this ability, either. It’d be a fairly tricky thing to accurately calculate.

hm. well, that’s disappointing.

Seems like it shouldn’t be any harder than a thermal FEA and there are many packages that will do that. I wonder if you can substitute some numbers (electrical resistance for thermal resistance, etc.) and use a thermal FEA package to do this? I’m only looking for DC values.