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. :(

http://www.stockly.com/images1/012805-NitricAcidChip1_IMGP0669.jpg

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

http://www.stockly.com/images1/012805-NitricAcidChip2_IMGP0671.jpg

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.

http://www.stockly.com/images1/012805-NitricAcidChip3_IMGP0676.jpg

There is a bond wire in the plastic.

http://www.stockly.com/images1/012805-NitricAcidChip4_IMGP0673.jpg

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. :(

http://www.stockly.com/images1/012805-NitricAcidChip5_IMGP0675.jpg

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

http://www.stockly.com/images1/012805-NitricAcidChip6_IMGP0677.jpg

It was fun while it lasted. ;)