Ok I’m working on a system 9 board that has some light battery corrosion damage I am trying to address.

The topside didn’t get hit too bad.
Clean…

As you can see, with just some light sanding I’ve been able to clean most of the damaged areas up.

The back side of the board looks like this along a lot of the bottom of the board.0D673DF8-0125-49A1-BD6F-44601F896B75 (resized).jpeg. As you can see, there are some areas where there is some green discoloration along the trace lines. It had popped off the masking. Am I correct that this is corrosion that needs to come out?

In the special solenoid area I’ve sanded what I thought was corrosion off, and I’m not really finding the classic black corrosion. There is some darker colored material over the copper, but it doesn’t come up easy. Should I keep sanding to copper in this area?

8F612E3C-348D-4654-8D28-83D75E6693C6 (resized).jpeg

I’ve got another really bad system 9 board that I consider a lost cause that looks like this.978BBD64-91D0-4956-ABC3-C336C82CEFEB (resized).jpeg

When you sand on it, the black comes off very easily, and I’m assuming that this is a completely corroded trace… the funny thing is the copper looks pretty good under the black.066A571D-6E2F-42E9-8192-2CD670ED92EC (resized).jpeg