[Kliment]

Given the corrosion of the traces they were no longer functional anyway - destructive testing on a few of them to identify the chips inside and getting microscope images of the dies is justified in this case in my opinion. Xray doesn't have the resolution in silicon that's needed to see the actual device structure. The information yielded allows the construction of an equivalent circuit, and possibly repair of the board. You only need to break open one of each type, at worst.