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I have a PCB that has 2 traces on one corner who's width only supports a ~10a load. I need support for a 20a load. Actually, it really only needs to support a 15amp load but I'm trying to build in some healthy breathing room.

Can I just solder a wire between the two leads in parallel with the trace? The terminal block and the relay both support 20amps and these are the only parts touched by the load. I know it's messy but I figure it's not as messy as having to wire all of this up off the PCB.

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3 Answers 3

Yes. Fixing production errors by using jumper wire is a time honored tradition by those blessed with hindsight.

For Power rails or low speed GPIO (Think Push Buttons inputs or LED outputs), a simple wire would work. As a precaution, you could cut the trace, and carry the full load on the jumper you are adding. If the jumper fails, the load would try to go over the 10A trace, and can cause issues (i.e. fire).

High Speed Signaling or Protocols with tight tolerances, RF signal traces, Traces that require uninterrupted ground/vcc planes under them, matched impedance, etc, require significantly more thought into it.

Then again, some have wider tolerances than stated. There are many hobbyist projects/hacks that add high speed USB ports to a board with a CPU that supports it, using nothing but regular wires and protoboard, not to spec.

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Awesome! I figured it would be fine but I just wanted to know what I would be getting myself into. Thanks! –  visionviper Jul 29 at 3:11
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+1 @Passerby I second that. If you are going to jumper it, cut the trace. You can also build up the trace using an excess of solder to thicken the trace, but using the proper gauge conductor is the way to go. –  Enemy Of the State Machine Jul 29 at 3:17
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Or bond the jumper along the full length of the trace (running solder along it) as an alternative to cutting the trace. –  Brian Drummond Jul 29 at 9:44

That is one option if your design can handle the additional (capacitive/inductive) impedance created by the wire.

Another option if the trace has no solder mask over it is to build up a large amount of solder along the trace in order to increase its ampacity.

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I actually saw this last option used on PCBs in several commercial products, suggesting it is not only used just as a last-minute fix. –  Matteo Italia Jul 29 at 10:47
    
+1 for mentioning the impedance concerns. I promise someone with a high-speed differential signal line will spend countless hours wondering why the info they got from this thread didn't work for their unmatched jumper wire. –  Joel B Jul 29 at 22:22
    
@JoelB I don't think that is a concern in a 15 Amp power rail. –  Passerby Jul 30 at 1:56
    
@Passerby - totally agree, but since this is an extremely high rated question about repairing a trace, I was simply pointing out that someone would stumble on this thread as trace repair help and wonder why their homebrew wireless project wasn't working. The only impedance concern here is the real resistance, but that isn't always the case. –  Joel B Jul 30 at 19:05
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@JoelB expanded my answer to reflect that. –  Passerby Jul 30 at 23:15

I would recommend cleaning the trace and end connections with sandpaper, laying clean copper wire on top of the trace between the terminals, then cover the top of the wire with solder, from one terminal to the other, making sure the solder flows between the wire and the trace.

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