Decapping ICs

[Andy Gelme]

hi All,

I'd like to decap some ICs for education purposes (Saturday mornings) ...

http://www.youtube.com/watch?v=mT1FStxAVz4

This would be a nice little task for our CNC mill.

Then, I need to get my hands on a modest amount of "fuming" (100%)
nitric acid. Any suggestions ?

It would be an excellent bonus if the chip survived and probing it
whilst running was an option.

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[Clifford Heath]

On 14/08/2012, at 3:50 PM, Andy Gelme wrote:
> Then, I need to get my hands on a modest amount of "fuming" (100%)
> nitric acid. Any suggestions ?

I think you'll find that strong nitric acid has fairly strong controls around it,
including invisible notifications, because of its numerous "interesting"
uses (no, I won't describe them). Perhaps go through an existing accredited
educational facility so as to avoid attracting the wrong kind of attention?

Clifford Heath.

[James Muraca]

On 14/08/2012, at 3:50 PM, Andy Gelme wrote:
> Then, I need to get my hands on a modest amount of "fuming" (100%)
> nitric acid.  Any suggestions ?

Check out Melbourne Etching Supplies.
http://www.mes.net.au/products/subcat-30-40.php
Have got other stuff from them, not the acid though

[Rob B]

Or http://www.instructables.com/id/Make-Nitric-acid-The-Complete-Guide/

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[wes Black]

NItric acid at fuming strength is a bit tricky to work with, and even worse with sulphuric acid mixed in. Strong oxidiser, strong acid, volatile, hazardous fumes, exothermic reaction on contact with water (add acid to water not other way 'round). Tendency to react with organic materials to in effect make them in to sort of gunpowder at best, nitroglycerin / gelignite at worst.

May be possible to use solvents more easily acquired from hardware stores or chem labs. Some IC packages are more amenable to decapping than others depending on exact resin used.

Suggest trying regular paint stripping gel first to see what happens. Least toxic, cheapest, and able to be blobbed onto IC and left there without need for CNC mill 'well' to be drilled in.

And it seems heat is the key.

If no joy, then I'd go for paint solvent, shellite, xylene, DMF, dry cleaning solution. If no joy, try different ICs to check if they're easier to decap. If still no joy, then try Nitric acid.

Wear thick nitrile gloves, fresh respirator cartridges apt. for organic chem fumes, goggles, coat, lots of ventilation, no flames. The worst is when one tries to scrub off something like the gooey mess from the IC then leaves wee blobs everywhere, inc. clothes, skin, eyes. Don't put it down a sink or in a plastic container or a breakable container. Maybe use diatomite kitty litter to soak up waste and spills, and dispose of thoughtfully somehow, maybe a uni chem lab. I know some guys in Campbeltown that do this professionally.

Plagarised from elsewhere:

1.  methyl ethyl ketone - readily available, but often ineffective

2.  dimethylformamide (DMF) - great stuff, but hazardous!

3.  cyclohexanone

4.  cyclohexanol - will attack some phenolics, not an easy feat

5.  methylene chloride - commonly sold as a paint stripper

6.  carbon disulfide - extremely flammable

7.  diethyltoluamide - great stuff, but hazardous!

8.  trichloroethylene

9.  ethylbenzene

10. dioxane

11. chlorobenzene

12. aniline - one of the few reagents that will attack polyimides and epoxies

<insert Dad-joke here... joke not found error...>

Wes

[Zac Watts]

I am a chemist/chem teacher, but I don't have access to a lab currently, but the i think the RMIT guys who were at the Raspberry Pi meetup the other day are from the chem dept there (Trevor definitely is, he was my 3rd year project advisor. Small world). Maybe you could hit them up for assistance. I don't know if they are on this list.

Or http://www.instructables.com/id/Make-Nitric-acid-The-Complete-Guide/

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[Luke Weston]

In terms of the educational value of showing people a bare IC die, it might be easier to find an EPROM or EPROM-based microcontroller with a quartz window.

I have a PIC16C765 around here somewhere, which is an old, obsolete microcontroller, but it's a 40-pin ceramic DIP microcontroller with a quartz window and a relatively large die, and you've got the whole interesting structure of a microcontroller that you can see on the IC, not just a relatively boring grid of EPROM memory cells.

Does that solve the use case you're looking for?

In terms of dissolving the chip's epoxy package, every time I've heard this process described or discussed it's always hot, concentrated nitric acid that is used. I've never heard any mention of any alternative reagent or solvent that is capable of doing the job.

Perhaps you can grind a little well onto the IC, put a little pinch of nitrate salt (potassium nitrate, sodium nitrate, whatever nitrate salt is easily at hand, I have some sodium nitrate here) into the well, and then put a drop or two of hot, concentrated sulfuric acid onto it to form nitric acid in-situ. You might get a little bit of nitrogen dioxide formed, but you probably get a little bit of nitrogen dioxide given off if you're doing it with hot fuming nitric acid anyway. And you still need to source concentrated sulfuric acid.

[Andy Gelme]

hi Luke,

On 2012-08-15 14:02 , Luke Weston wrote:
> I have a PIC16C765 around here somewhere, which is an old, obsolete
> microcontroller, but it's a 40-pin ceramic DIP microcontroller with a
> quartz window and a relatively large die, and you've got the whole
> interesting structure of a microcontroller that you can see on the IC,
> not just a relatively boring grid of EPROM memory cells.
>
> Does that solve the use case you're looking for ?

Basically ... yes. During a Saturday morning "workshop" ... we could
look at it through the stereo microscope.

Borrowing your IC for a meeting would be good, thanks.

> Perhaps you can grind a little well onto the IC, put a little pinch of
> nitrate salt (potassium nitrate, sodium nitrate, whatever nitrate salt
> is easily at hand, I have some sodium nitrate here) into the well, and
> then put a drop or two of hot, concentrated sulfuric acid onto it to
> form nitric acid in-situ.

However ... using the CNC mill to make a well ... and then using acid to
etch into an IC ... also demonstrates an interesting technique. That
would be a nice bonus.

Thanks everyone who has replied to the original question. The answers
by themselves have been informative and interesting.

I'd still like to see if we can do this.

[Andy Gelme]

hi All,

On 2012-08-15 14:02 , Luke Weston wrote:

> I have a PIC16C765 around here somewhere, which is an old, obsolete
> microcontroller, but it's a 40-pin ceramic DIP microcontroller with a
> quartz window and a relatively large die, and you've got the whole
> interesting structure of a microcontroller that you can see on the IC,
> not just a relatively boring grid of EPROM memory cells.

Thanks for all the suggestions and offers.

Last Saturday, the young hackers were able to look at an EPROM IC
(thanks Bernd) and a microprocessor (thanks Luke) through their quartz
windows. This certainly achieved the main objective of actually seeing
the transistors that make up a complex IC.

Later on, I'd still like to actually de-cap an IC ... so show how that
is done. So, I'll follow up the various suggestions and contacts for
getting hold of some strong nitric acid (if possible).

[tubular]

A bit late to the party, but for a less chemical approach you can also just mill it until you get close to the die like I did here 

http://forums.parallax.com/attachment.php?attachmentid=85313&d=1316653089 

cheers

Lachlan 

[Zac Watts]

A follow-up to the decapping ics video:

http://www.youtube.com/watch?v=eoRVEw5gL8c

[Andy Gelme]

hi All,

On 2012-09-4 17:07 , Zac Watts wrote:
> A follow-up to the decapping ics video:

> http://www.youtube.com/watch?v=eoRVEw5gL8c --

That was a very cool video. I'm looking forward to seeing what happens,
when Ben removes the oxide layer and tries again.

Recently, there was a tear-down of the Apple A6 microprocessor in the
iPhone 5. This is what you can do if you de-cap an IC with an ion beam
(forget the nasty acid) ...


http://www.chipworks.com/blog/recentteardowns/2012/09/21/apple-iphone-5-the-a6-application-processor


http://www.chipworks.com/blog/recentteardowns/files/2012/09/APL0598_APL0-589B01_127521_.jpg

[Zac Watts]

More information about decapping ICs:

http://zeptobars.ru/en/read/how-to-open-microchip-asic-what-inside