On Mon, 19 Feb 2018 09:56:55 -0800, John Robertson
wrote:

It doesn't always work, the corrosion can be too extensive for
economical repairs, but boards that have been treated as advised have
rarely failed if they worked after cleaning (and corroded IC sockets,
etc. replaced). Boards where traces are missing are normally too far
gone, but have been saved with extensive repairs.

You're doing better at repairing corrosion damage than me. The
problem is that the corrosive fluid tend to narrow the trace width of
traces that are still making a connection. Add a little current
through the trace, and you have a fuse. Also, the electrolyte acts
like, well... and electrolyte. Two parallel traces, separated by a
hygroscopic PCB, with a DC voltage across the gap, is going to slowly
erode one trace, while building up the other. The net result is that
it works for a while, and then craps out again.

I just had both of these effects happen while trying to fix a Rayovac
LED head lamp. I think it was this model:
https://www.walmart.com/ip/Rayovac-Virtually-Indestructible-3-AAA-Industrial-Grade-LED-Headlight/53982706
It's quite a decent head lamp, at a good price, and is rate to be
water resistant up to IPX4 (splashing water). However, there's no
protection against the alkaline batteries leaking all over the PCB. I
gave up after it came back the 4th time with essentially the same
problem.

The damaged PCB is in my "to be recycled" bin. I can take a photo and
post it if anyone wants to see the mess.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558