Dual Traces

Community PCB Design
1

Hello

I was wondering if putting two overlapping traces for the same high power signal (one trace on top and another on bottom layer) helps increase current carrying capacity instead of increasing width of the trace when limited to only 1oz thickness (BatchPCB for example).

Any idea if this would practically work?

Thanks

2

Two 50mil traces will handle the same current as one 100mil trace.

So yes!

-Bill

3

Thanks. this will help a lot in sections with no ground plane.

It was hard to get minimum width according to trace width calculators on the web when component pins spacing is tight.

4

Just make sure you have enough vias to connect the two sides to pass the current and reduce the connection impedance.

/mike

5

phalanx:
Two 50mil traces will handle the same current as one 100mil trace.

So yes!

-Bill

Agreed - figure I should add some more details as to why:

I would argue that in most cases, two 50 mil traces will be able to handle even more current than a 100 mil trace, due to having the heat spread out better.

However, their resistance will be ever so slightly higher due to the way etching will eat into the sides of your trace a bit.

6

NleahciM:
I would argue that in most cases, two 50 mil traces will be able to handle even more current than a 100 mil trace, due to having the heat spread out better.

Although I guess if you're worried about traces actually getting hot, the appropriate solution would probably be to use wiring instead of traces, I can't help but wonder.. wouldn't your statement only be true in those cases where the two traces run dissimilar paths on the PCB?

As Mike points out, there may be technical reasons why you’d want to run vias between them. This would imply they run the same path*. Radiant heat transfer should be the same, convection should be a bit improved, but performance of heat conduction I think would be reduced, as heat transferred through the board would simply compete with the heat from the mirror trace with less dissipation you might otherwise have (from unrelated traces or copper fill-ins).

  • Though they could still run dissimilar paths, as long as they ‘meet up’ where the vias are, I suppose.
7

Kamiquasi:

NleahciM:
I would argue that in most cases, two 50 mil traces will be able to handle even more current than a 100 mil trace, due to having the heat spread out better.

Although I guess if you're worried about traces actually getting hot, the appropriate solution would probably be to use wiring instead of traces, I can't help but wonder.. wouldn't your statement only be true in those cases where the two traces run dissimilar paths on the PCB?

As Mike points out, there may be technical reasons why you’d want to run vias between them. This would imply they run the same path*. Radiant heat transfer should be the same, convection should be a bit improved, but performance of heat conduction I think would be reduced, as heat transferred through the board would simply compete with the heat from the mirror trace with less dissipation you might otherwise have (from unrelated traces or copper fill-ins).

  • Though they could still run dissimilar paths, as long as they ‘meet up’ where the vias are, I suppose.
Your heat is getting split across the two sides of the PCB. This is an improvement. You're right that you'll be heating up a smaller volume of the FR4 - but it's an insulator, so I just don't see that as being a major concern.