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I previously worked on Virtual Reality and other hardware at Valve.  I currently work at Google[x].

Prior to starting at Valve, I built computer peripherals such as keyboards, mice, and joysticks that were designed to be used inside MRI machines.  My company, Mag Design and Engineering, sold these devices directly to researchers at academic institutions who used them to publish scientific papers in peer-reviewed journals.

After work, I spend time on many different types of projects that usually involve circuit design, machining, material selection, and general fabrication/hacking.  My favorite place to be is my home workshop.

ben dot krasnow at gmail

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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:

  1. 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

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  2. 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.

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

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  4. 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

    ReplyDelete
  5. 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!

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  6. Hello,

    can chips work after deccaping?

    Vena

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  7. 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.

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  8. 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

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

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  10. 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.

    ReplyDelete