3 ms·
You'll probably see this on the Sparkfun saga, but the way to remove it at the Atmega lab (with a hotplate and acetone) is quite dangerous. Don't try that at h
by reemrevnivek 15y ago
You'll probably see this on the Sparkfun saga, but the way to remove it at the Atmega lab (with a hotplate and acetone) is quite dangerous. Don't try that at home.
Instead, drop the whole chip in a test tube of fuming nitric acid at room temp, and let it work slowly overnight. Anything with fuming nitric acid is dangerous, but this is much safer than the hot plate method. See this tutorial by Travis Goodspeed:
http://travisgoodspeed.blogspot.com/2009/06/cold-labless-hno3-decapping-procedure.html http://travisgoodspeed.blogspot.com/2009/06/cold-labless-hno...
- shabble 15y agoYeah, it's not something I'd attempt without a fume hood and someone who knows what they're doing. The pic of mine had a simple brazed metal 'lid', which I managed to separate by scraping out the solder with a scalpel, and then finally a hot-air gun to melt the rest and pop the top off. I'm sure I've seen references to HF (Hydrofluoric acid) used in depackaging, but since it also etches silicon, I'd imagine you'd need to be pretty amazingly accurate with it.
- reemrevnivek 15y agoOrdinarily, you use (fuming) nitric acid. This dissolves the epoxy packaging, but leaves silicon and metal intact. You need the HF to etch the top layers of metal/silicon from the die. These layers are above the actual circuitry, and help increase security so that an attacker can't steal IP by using nitric acid and microprobes or UV light to modify the operation of the IC. Flylogic has a special technique by which they selectively etch areas of the metal layers, but not the circuitry below.