Monday, August 13, 2012

Decapping ICs (removing epoxy packaging from chips to expose the dies)

I thought it would be interesting to try decapping some chips. This involves using fuming nitric acid, which also seemed fun, so I thought I would give it a go. The process starts by milling a precise pocket into the IC using my CNC machine. I used carbide tooling to cut the glass fiber/epoxy material. I then put a drop or two of the acid into the pocket, and raised the temperature to about 100*C. The acid dissolves the epoxy packaging as it sort of "dries". I added more acid to the pocket every few minutes. After about 10 minutes, I washed the IC in acetone, then reapplied acid if there was still material left on the die. Eventually, it was all cleared away, and I had a nice decapped IC.

10 comments:

Schwuuuuup said...

Hi,

I wonder if this works on IC dies, that have been glued to a PCB by a Blob ... Epoxy?

I have 53% NHO3... which was kind of useless till now... maybe this is not strong enough... or, as you suggest, I have to heat it up

Greetings
TOM

sanpedro said...

I sugest you to send a couple of working ic's to this guy http://www.youtube.com/user/mikeselectricstuff
maybe he can find a way to use his thermal camera while chips are working.
I'm really curious to know if visualization is possible.

madis_l said...

BTW You have ultimate probe - scanning electron microscope. Can Your SEM display such low as 5V potential differences?

Hash said...

Ben,

Interesting video, I have always thought about doing this but had no idea where to source the necessary chemicals.

How do you go about getting hobbyist quantities of things like Nitric Acid? Friend of a friend of a chemist... Or are there websites that cater to DIY chemist markets?

-Hash

Ben Krasnow said...

Hash, it is no doubt difficult to get chemicals as a hobbyist. Most of the large suppliers will ship only to universities or established businesses. If you have a friend who is willing to help, that is one option. I've heard some online places will ship to individuals. Try these: http://www.chemical-supermarket.com/
http://www.elementalscientific.net/
http://www.unitednuclear.com/

Good luck!

Anonymous said...

Hello,

can chips work after deccaping?

Vena

Ben Krasnow said...

Vena, yes the decapped chips definitely work after the process. I just decapped two 555 timers, and plan to inspect them with a scanning electron microscope while the chips are active.

Anonymous said...

Hello Ben,

within my PHD I wanna do some experiment with FPGA. I wanna remove package but chip must be working after this procedure. I tried use HNO3. The whole chip was immersed in the acid (just test of the acid). But nothing happend. I try your procedure from the video and I will leave here some message after.

Vena

Mitch Davis said...

You could use a bond wire attached to a dip pin as a probe, and position it with your CNC mill.

Anonymous said...

For those without access to nitric acid, I found a different method of getting to the silicon inside ICs (it is a little crude though:
heat the IC as hot as i could with a propane torch
then quench into cold water, after a few tries I was able to get the plastic casing material to crack through thermal shock leaving the die exposed. It's no good if you want it to still work but if you just want to remove the top to look at the insides through a microscope/magnifying glass it's fairly effective.

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