PCB Through Hole Repair

[crazifunguy]

Anyone have an idea for fixing plated through holes on a pcb? I see that there are sites that can do this and the parts are available but the cost is pretty OUCH!!. I need to repair about 15 of them. I am trying to rescue a damaged plate amp before it hits the recycle bin. I could do wire jumpers but that gets messy and isn't worth the time.

[AKHeathen]

is this judt through-hole connections that join traces from one side to another, or the through-holes to mount components? really, the legs are what i use when a sleeve pulls through. it comes in pretty handy to have a few longer resistor cut-offs to use for circuit/trace repair

[Enzo]

If it is just a plate through hole, stick a piece of bare wire in the hole and solder it on both sides of the board. As AK said, if the hole is for a component lead, then just solder on both sides of the board. No need to run jumpers if the traces to and from the hole are intact.

[Buriedcode]

My two cents/pennies:

Both the above suggestions are quick and simple, as well as fucntional - they've already covered most situations. But if its a blind through hole (like under a 4700uF cap) where traces make contact with the top connection, then aside from using eyelets/rivets (ebay has some, MegaUK, and I believe a french company CIF), I *sometimes* use copper foil. Generally 0.1-0.2mm. Must be plain foil, no adhesive.

I'm assuming you've pulled the plating out the hole, but both pads are intact either side? If a pad has lifted, but still connected, you can glue it back down with epoxy, holding the pad up with tweezer as you apply the glue, then press it down with something like an eraser on the end of a pencil.

Once both pads on either side are fixed, run a drill bit trhough the hole to clean it out of gunk, and to make its sides smooth. Roll a small piece of foil around a drill bit's shank (diameter slightly smaller than the hole). Length of the 'tube' would be around 3mm for a 1.6mm PCB, should over lap slightly. I use broken/old tunsten carbine PCB bits for this, as they are reduced shank, which spreads the top of the foil over the hole. Once in, carefully turn the board over and put the bit through the hole on the otherside, spreading it over the hole. Then apply pressure on both sides so it sits flat, and *carefully* solder it on both pads. Its horrible when the foil folds inside the hole, blocking it which is why its not a favoured method.

This is far from ideal, as the foil isn't 'fixed' in the hole, its simply held there by the solder either side - so mechanically, its not strong. But all it needs to do is to wick/flow solder up through the bottom of the plated hole, and spread over the top pad, so its filled. Ultimately the solder does the work, the foil is just placed there for it to flow along.

Of the few I've done of these, they look neat (can't always tell) but if you plan on desoldering the part, the foil WILL come out again, and the process repeats.

Pro's: relatively cheap, good electrical connection (for power traces), and looks good.
Con's: Fiddley, annoying, time consuming and mechnically weak compared to the original hole.

Had to do this recently when I removed a power cap from a board - took perfectly formed plated through-hole with it Thats why you never use force when desoldering.... for heavy components, hot air at a distance, flux, and some light 'tapping' on the board - it should drop out under its own weight.

BC

[Enzo]

Ah yes, a hole not accessible. In those cases, I usually find two points where I can solder a wire in place of the missing connection. The trace on the blind side must eventually connect to some component that sticks through the board.

I am ignoring surface mount boards or multilayer boards where internal connections are made.

[Buriedcode]

Originally Posted by Enzo

I am ignoring surface mount boards or multilayer boards where internal connections are made.

I think we all try to ignore internal via's... then its just a case of a schematic, kynar wire, and headscratching.

SMT is sometimes easier, as generally they have less current running through the parts, which means you can use thin wire. When a trace carries >4Amps it starts getting messy :/

[Enzo]

Most of the stuff I work on won;t be dragging 4A through a plate-through. At least not a single one. Might see three or four in a short row all in parallel.