Repair of damaged/corroded gold connector 'fingers'?

[Brent Hilpert]

Mr Ian Primus wrote:
> 
> Recently, I've run across some circuit boards with damaged connector fingers. Some are badly scratched and worn, the gold plating almost gone, and others are actually corroded - the copper has corroded, possibly due to previous damage to the gold plating.
>... 
> The scratched/worn connectors seem to still work, at least most of the time. The corroded ones wouldn't work until I cleaned off the corrosion. Not an easy thing to do - I ended up resorting to Brasso, a brass polish. Now, this is NOT the thing to use to clean edge connectors! DON'T DO IT! It WILL take the plating off. In this case, the plating was already gone, and the copper track underneath was corroded. Cleaning the corrosion off with the Brasso, and subsequent cleaning with alcohol to clean off the Brasso, removed the corrosion leaving a shiny copper track. The board worked fine, but for how long? How long until the corrosion comes back, or the copper oxidizes?
> 
> Is there any way to repair or replate fingers like this? Obviously, tinning them with solder would prevent oxidization, but this would make that 'finger' much too thick, and risks damaging the connector it plugs into. (Operators loved to "fix" burnt edge connectors on arcade boards like this, and it works for a while, until you go to unplug and replug it, and the destoyed connector no longer mates with the board correctly.)
> 
> Just something I thought that others might have an input on - I mean, in this case, these Nintendo cartridges are not worth the effort of any complicated repair, but it raised the question in my mind, and I know I've run into this on computers before.

There is a dip solution one can purchase that does a nickel plate. The bottle
is covered in toxic/hazardous/poisonous/special-discard-procedure warnings,
however. Never used it, I've just seen it a store.

Along simpler lines though, it is possible to leave a very thin solder plate on
the bare copper by tinning it, and having a cloth or slightly damp sponge at
the ready to immediately wipe off the excess solder. Some skill or practice may
be required but it can/will leave just a 'plating', thin enough to be
inconsequential to the edge connector receptacle.

On the other hand, I have bare-copper PCBs with edge connectors I built as a
kid in the 70's that still have no corrosion and are still functioning with no
problems. YMMV with climate I suppose.