"Frogwatch" wrote:

What can be used to dissolve cured epoxy?

Not much.

What can be used to dissolve a thin film of cured polyimide.

Not much.

OK, if nothing dissolves it, what will de-link it? Will UV light do
it?

It will damage it.

Could strong UV light be used to soften epoxy so as to be able to
get
better adhesion to a later layer?

No, but 24 grit paper and elbow grease will improve the mechanical
coupling of old and new.

Lew