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I've made a couple of PCBs which need the odd few 10 mil tracks, but are mostly 20/30 mil. Unfortunately the etching process isn't fantastic and there are numerous breaks in the traces, most of them small.

I've managed to convince solder lumps to go over the top of the smaller gaps, and have used components legs to bridge some of the larger ones. The solder lumps don't feel particularly reliable though, and there are some gaps which are too small and awkward to get a piece of wire across but too big to be bridged with just the iron.

Are there any standard ways to reliably fix up broken traces?

Update: Thanks for the suggestions everyone!

I found and tried out a silver conductive pen. As a first time user I found it difficult to dispense, and obviously I didn't use enough of it or mix it properly because it didn't even end up being conductive.

It seems like the main problem was that I was trying to use pieces of wire which are too short. I found some small gauge tinned wire and used longer lengths, running it over significant lengths of good track on either side of the fault. That makes it much easier to position, and you can tack them down one end at a time.

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7 Answers

up vote 14 down vote accepted

I use wire-wrap wire to fix broken tracks, or to modify boards. It's very thin, and easy to solder because of the silver coating. It breaks easily so some sort of glue to hold the wires in place is advisable, I just use masking tape, sometimes.

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A hot glue gun is invaluable for this sort of thing. It will melt quite quickly near soldering irons, so glue after things are in place, but that property means you can fix your fixes if need be without a huge headache. –  Lou Jan 8 '10 at 16:34
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Buss wire too. I use tweezers to hold it in place while the solder cools. –  jluciani Jan 8 '10 at 19:25
    
yes, wire-wrap wire is perfect for these kinds of "edits". And if you use wire with the same color insulation as your soldermask (green wire over green board), it's very hard to see the edits! :) –  todbot Jan 12 '10 at 0:06
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I've had the same problem in the past, if you really don't want to etch another one, I'd just solder a jumper wire across the gap (use single strand/bell wire, it holds it's shape better) I've tried conductive pens in the past and they can be a bit hit and miss, not sure about the paint tho, it may work well if you build up a few layers

here's an example -> PCBrepair

It's ugly but it works!

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If you're having trouble etching i've made a video explaining a simple method for making PCBs at home -> youtube.com/watch?v=frsDN7usyCs –  Jim Jan 8 '10 at 8:45
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I use solder lumps and component legs. :)

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Sometimes it is best to run a wire between the two nearest solder pads along that trace rather than try to fix it in a very tight area. If you do this then put a few drops of super glue on the wire after you are done to hold it in place and prevent vibration from breaking the connections.

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Clean the traces with steel wool and tin them. Then solder 0.2mm (32 AWG) tinned wire onto them. This diameter lets itself bend easily to follow the traces' turns. The small diameter also means that during soldering only little heat is transported over the wire to points you soldered earlier; a thicker wire may come loose again.
I find Erem 102ACA precision tweezers handy to place the wire,

Erem 102ACA tweezers

and a pointy knife like X-Acto to cut the wire after soldering.

X-Acto knife

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One option is a "conductive pen" or "conductive paint"...dunno how well they work though.

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One maintenance shop I worked in had trace repair kits. They had various sections of straight traces and different types of pads.

Carefully remove any conformal coatings from the board, trim the new trace to size (about 5x the width of the trace works well for overlaps on each side,) and carefully solder it to the original trace. Clean it well, then cover it with conformal coating spray or a thin epoxy. I've been able to successfully fix some pretty bad boards (holes burned through) after filling any holes with epoxy, then using this method.

Unfortunately, I don't know where to get these, but I would try any of the "usual suspects" such as DigiKey, etc...

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