Decapping an IC

[Grant Stockly]

I tried disolving the epoxy on some PAL ICs to view under a microscope with the goal of reading the fuse map. I wasn't so successful.



We've got a hot plate, IR temperature probe, and a chunk of steel.



After about an hour, nothing. The hole on the chip to the right was milled in it with a dremel. It didn't help. The plate got hot enough at one point to light the nitric acid on fire. Not cool. Its a good thing I did the project in a negative pressure fume hood.

After doing this for an hour, I gave up. The acid is just too dilute. So I took it over to the surface polishing tools used for steel and took the plastic down to the silicon layer.



There is a bond wire in the plastic.



I think a lot of the black stuff is plastic that was left behind. I ground too heavily on one side and now it looks like a mirror, no traces at all.



The further you go down, the more black IC epoxy junk we see.



It was fun while it lasted.