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.

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

[SmokeandLights]

@11:06 It looks like you are looking into a swimming pool. It's crazy how "deep" it looks at that magnification.

Some recommendations if you want to keep trying this:
Get some micromesh (that's the brand name) sanding pads for when you get close for manual sanding. They go up to VERY high grits, and get pretty close to the "grit" of polishing compounds.
There's probably a small container of red or green jeweler's rouge included in your dremel kit. Get a little of that on the felt point, instead of car polish. It will also polish jewelry nicely. You do have to clean it off with alcohol after. it turns into a black sludge while polishing.

I've never done this before, but I do a lot of sanding & polishing.

Cool shots. I'm wondering if the places where the die looks more red is actually due to the heat of polishing. Not like "red hot", but more like the various colors that metals turn (like discolored chrome motorcycle exhaust pipes).

[csbluechip]

Well done! Very impressed to see that done by hand!

[StadtFuchs]

I have never seen the surface of a COB before. Thanks for all the work to show it to us! 👍

[Vpg]

We need to find a way to hack into/read these!

[BGTech]

Use a heat gun, it will turn that expoy into goo. You can use a similar method to open regular flat pack chips.

[gabrielv.]

Sadly it seems that its literally impossible to just melt the blob, since the chip has no outside shell?

[coondogtheman]

I'm curious if there's a way to extract all the data off a chip like this. I see tons of test points. I assume it has basic logic data as well as the audio data itself. I have a few of these greeting card chips and they all work including one that records.

[warunakumara]

sir can we replace cob ic, can we take its internal data