While sulfuric or nitric acid is the best way to do this, you can also decap using a box cutter and some patience. I recently did this to figure out if an opamp I bought was fake:
I’m going to try and get setup to decap properly. But the for those more concerned about using the required acids, a box cutter can give some insight into what’s going on in many devices...
We occasionally used a regular old propane torch at a previous employer, mainly looking for counterfeit power FETs. It'll burn the bond wires and such off an IC, and certainly isn't going to result in great quality images but it's not too hard to get rid of the plastic without damaging the silicon beyond recognition.
http://41j.com/blog/2019/03/various-op177-die-images/
I’ve posted some better images here:
https://twitter.com/new299/status/1111301269988106245?s=21
I’m going to try and get setup to decap properly. But the for those more concerned about using the required acids, a box cutter can give some insight into what’s going on in many devices...