Mechanically Decapping a Chip-On-Board (COB)
Decapping microchips is the process of removing the protective package that surrounds the silicon die. In this video I take the PCB out of a greeting card which has an epoxy blob that contains a COB. There are several means to decap a COB such as using strong chemicals or lasers to remove the epoxy. I've opted to go for a simpler (and crude) method: mechanical removal of the epoxy. While it will likely lead to damaging the silicon die and certainly not leave it in an operating state, it does work.
The microscope I used in this video is a metallurgical microscope; the cheapest one I could find on eBay (it was used). The camera I used to film it was also the cheapest USB camera designed to fit a microscope eyepiece that I could find on eBay. The quality of the pictures is certainly not what I would consider to be anywhere near 'professional', but it certainly does a very good job for what I need.
If you are interested in this sort of thing, I highly recommend checking out Ken Shirriff's blog at https://www.righto.com/. Also check out Silicon Pr0n at https://siliconpr0n.org/wiki/doku.php for lots of amazing die shots of all sorts of different chips
0:00 What's All This?
2:35 Using Sandpaper
5:51 The Silicon Die Is Visible!
6:29 Microscope - Part 1
8:50 Using a Rotary Tool
10:37 Microscope - Part 2
13:04 Microscope - Part 3
14:53 Squeak Squeak Squeak
14:58 Microscope Montage
17:02 Conclusion