Philco Predicta board lifted trace and trace corrosion.

[Yamamaya42]

Originally Posted by Electronic M

Trace lifting is common on these first generation PCBs as long as everything that was connected to the trace is still electrically connected (has continuity), and the foil isn't flopping against and shorting to something it shouldn't contact then everything is fine. If a section is missing just solder some wire in to bridge what's missing.

As for corrosion some boards added early conformal coating to the unsoldered traces to prevent corrosion ,some didn't, others just tinned all the trades in a solder bath. Bare copper corrodes over the years especially if stored in a humid environment. You can polish off the corrosion and flow solder over it to keep it from coming back. If it's not open and you plan to keep it in a climate controlled environment you could also choose to ignore the corrosion...If it hasn't chewed it open in 60 years it probably won't in another 60 in better storage conditions.

I hate to be “nit-picky” here, but the terminology I have seen being used here is incorrect,
And as someone who has been in the major PCB manufacturing industry ever since HS, seeing this error all the time kind of gets under the skin. :O

The correct term for the protective layer on top of traces is the solder masking, and the lettering and diagrams over that, silkscreen.

Info here
https://www.ablcircuits.co.uk/pcb-layers-explained/

Conformal coating is a clear protective layer often sprayed on after the board is complete and passed all testing, it is a special polymeric film forming product that protects circuit boards, components, and other electronic devices from adverse environmental conditions. And often has a dye added so it can be seen under UV light.
Info here.
https://en.wikipedia.org/wiki/Conformal_coating