Technology
How-To: Dissolve IC packages

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Travis Goodspeed demonstrates how to chemically remove (or ‘decap’) the plastic surrounding those delicate and incredibly cool looking wafers chips –

The following are instructions and matching photos for removing the packaging of microchips without a proper chemical laboratory. Neither a hot plate nor a fume hood is required, and the only chemicals necessary are fuming nitric acid and acetone. The result is a bare die, with bonding wires. The bonding wires may then be removed and the die photographed using microscope.

The same as any author of a lay chemistry article, I must caution you to be very careful with the procedure that I describe. If you’ve no prior experience with chemistry, purchase an introductory book and study the safety instructions thoroughly. Nitric acid in these concentrations is nasty stuff, even when cold.

Like the man said, safety first – but be sure to send us some sweet macro shots once you’re done!
[via EMSL]

Update:: In the comments, John Cabrer writes –

Actually, you can accomplish the same task using nothing more that a propane or butane torch that you can pick up at the hardware store. Everything but the silicon turns to dust. This method has the added benefit, that there are no wires remaining to remove.

22 thoughts on “How-To: Dissolve IC packages

  1. Sorry to spoil the fun, but fuming nitric acid is off limits, a controlled substance, because it is one of the essential ingredients for making any member of the large family of highly potent, difficult and dangerous for handling, explosives, which I will NOT name online.

    1. Do you have a link to a list of such controlled substances? I don’t see it on the lists I’ve browsed, and the wikipedia article doesn’t mention controlled status (though it may be inaccurate).

    2. Nitric, fuming or not, is not a controlled substance. It’s used in making a huge percentage of known explosives including EGDN, “nitroglycerin”, RDX, etc. It’s also legal to make these explosives (at a federal level) in all 50 states without a license of any kind. I urge you to review whatever source of misinformation you have, because what you said is simply not true. Review the ATF Orange Book for more info on the laws. It’s also used in thousands of other processes unrelated to explosives.

      Now, it is common for chemical companies to deny sales of anything they want to anybody they want, especially because of liability concerns. Somehow in our society if you spill hot coffee in your lap, it’s not your fault, and you can file a lawsuit against McDonald’s. It’s no wonder places won’t sell you chemicals without jumping through hoops. So jump through them! Spend the $50, setup an LLC, get a D&B number, and buy whatever you want (like I do).

  2. Actually, you can accomplish the same task using nothing more that a propane or butane torch that you can pick up at the hardware store. Everything but the silicon turns to dust. This method has the added benefit, that there are no wires remaining to remove.

  3. An IC “wafer” contains many “Chips” or dies. Each die is a complete design (IC).

    Typically, a package (black plastic with pins, contains 1 die. I have never heard of a package containing a wafer and I can not think of anything useful from it. The package can contain multiple dies (usually of different types of functionality).

    Picture this.

    In a single package, the CPU with a memory die mounted directly to the CPU die. Reduced latency of the memory because signals do not have to go out to the motherboard. Now that is a package I would like to see inside.

    As mentioned before by others, be careful when working with any chemicals.

    Thanks

  4. Nitric acid is not a regulated compound but it is very dangerous. Does anyone know if HCL, which is far safer, be used instead.

    1. I’m not sure I’d consider HCl any safer. The hydrogen chloride gas comes out of solution pretty easily, and then goes right back into it when it touches sweat, or your lungs when you breathe it in. You pretty much have to use a respirator with acid filter cartridges installed. Doing that doesn’t protect your skin though. It burns and gets really itchy and irritated. Nitric burns too, turns your skin brownish color, but never seemed to bother me. A fume hood is your friend in either case, or just do it outside and be careful.

      I don’t think HCl will attack the plastic chip carriers but should eat the ceramic chips. Not sure how it behaves when it hits the silicon die either.

  5. As part of my job I do this all the time. If all you want to do is get access to the die surface using nitric acid, a hotplate at 80C and a plastic dropper and a steady hand will remove the top of the package and leave the chip sill functional. As long as the bond wire are gold and there is no surface copper on the die. If the bond wires are copper or there is copper on top of the die then a mixture of nitric and sulfuric acids will preserve the copper. A lower temp on the hotplate will also be a good idea. This is all to keep the chip functional, but if the die is to be removed then just 3 to 4 minutes in 180C nitric will do the trick.
    Acid are dangerous and use gloves and ventilation.

  6. where can i get the acids to make aqua-regia i heard draino and something else will work but i dont want to blow up lol need help finding a cheaper alterntive then laboratory grade

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