IRIXNetwork

wroteafaq · 02-04-2022, 08:54 PM

Right. But what I'm saying is that there's no reason to replace the solder mask *or* repair the burned up area with copper tape.

robespierre · 02-04-2022, 08:58 PM

The most valuable material for repairing pad or trace damage is a thin, two-part epoxy. There are types made specifically for PCB repair (like in the Circuit Medic kits) but regular hardware store Devcon or Loctite epoxies will also work. Their use is documented in IPC 7721 §3.5.1. In your case, if there is charring to the board substrate, you would grind away any charred material with a foredom set at low speed (~2000 rpm) and an abrasive rubber tip, then clean with an appropriate solvent (ethyl acetate/acetone mix works well), let dry while mixing the epoxy. You want to fill the hole with minimal mounding because you need to grind or scrape it flat later. The epoxy cures in 24 hours at room temperature or in 1 hour in a 165° F (75° C) oven. If the hole is relatively shallow you can combine this step with the copper land repair, which involves cutting a thin foil to the correct size and fixing it down with epoxy. As the post above says, the copper is only needed if it is required for the circuit's function.

Nichosen · 02-04-2022, 10:08 PM

Wroteafaq is on the right track…
There’s no need to repair the big copper area. You’ve got plenty of copper to solder to as well as on top of the existing caps… it’s the same electrical point.
But the traces below in your picture might be damaged and these are harder to Ats why I recommended a glass fiber pen… it’s like a pen with an abrasive tip that kind of sands off the lacquer to reveal the undamaged copper of the traces… this is so that there’s something for the new solder to stick to.
You can use an exactoknife but be super careful because it’s very easy to scrape off to much.

The silver epoxy works fine on courser traces but the looks like the thickness of a hair..

To bad I don’t have pictures of my last repair.

megaimg · 02-07-2022, 02:10 AM

I was able to get out one of the capacitors!
Bellow is the mouser part best match my readings....

https://www.mouser.com/ProductDetail/791-1206B394J500CT