How to decap an IC

[Grant Stockly]

This is a collection of instructions from the web on decapping ICs. I have not successfully decapped any ICs yet, but when/if I do I will post my results.

[Grant Stockly]

From: Jon Hiller : hiller-at-anl.gov
Date: Thu, 24 Jan 2002 19:26:21 -0600
Subject: IC package removal

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Does anybody have a chemical solution for removing IC packaging without
damaging the internal components? Simple grinding from the top down is not
suitable because I need all the interconnects intact. Any help in this
matter is greatly appreciated.

Sincere regards,

Jon Hiller
================================================== ================
Jon M. Hiller
Argonne National Laboratory
Materials Science Division
Electron Microscopy Center
Tel: 630-252-9558
Fax: 630-252-4798
Email: hiller-at-anl.gov
================================================== ================


From daemon Thu Jan 24 19:34:57 2002

[Grant Stockly]

From: Diane.Ciaburri-at-gd-ais.com
Date: Fri, 25 Jan 2002 08:50:58 -0500
Subject: Re: IC package removal (LONG)

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Jon,

I assume you're speaking about plastic packages since you want a chemical removal technique. Below your message is a summary of responses that I received when I asked a similar question. I can't comment on them, because my project dried up after I asked the question and I never got to try any of the techniques, but there look like some good ones.

Diane Ciaburri
General Dynamics
Pittsfield, MA


<Note from logjam, the following posts until noted by me are a part of this e-mail. I'm separating them for readability. I'm also fixing the line break issues that make the post very hard to read and doing some minor formatting>

[Grant Stockly]

<Part of the last post>

Here's the summary (long) for all those interested in deencapsulating plastic encapsulated ICs. I have no preferences as I haven't tried any yet, but thought the fuming sulfuric acid might be 'fun'. Thanks again!

[Grant Stockly]

<Part of the previous post>

-- [ From: Garber, Charles A. * EMC.Ver #3.1 ] --
Hi Diane,

The way this is generally done is to mill the plastic down on a grinding wheel to the point where only a fairly thin layer of plastic remains.

Then, using a plasma etcher, and a mixture of oxygen to CF4 (for example, 30% oxygen/70% CF4), whereby the oxygen etches away the plastic and the CF4 etches away the glass frit that is usually found in the plastic, you can remove the remaining plastic (package) without damaging the device itself. Different people like to use different gas ratios, of course, and that is probably a function, at least to some degree, of the concentration of glass frit in their particular plastic.


The SPI Plasma Prep II unit, as shown on URL http://www.2spi.com/catalog/instruments/etchers1.html in the world, is probably the most widely used unit for doing this type of operation. It is inexpensive and highly reliable, and requires virtually no maintenance.

Chuck

[Grant Stockly]

<Part of the previous post>

The ion beam approach works well. I have not used it recently on finer pitch ICs. With as-built feature sizes of 2-4u, it is fine. It will stop at the passivation and leave the Al bond wires intact. The resulting package looks like it has a V-shaped pit in it (which it does). The extent of the pit depends on the size of the die and if you want to blast down to the lead frame or substrate.

I have not done this on finer pitch devices. I would be a bit skeptical about these mostly because of the smaller bond pads. The etching would still stop at the passivation.

There are numerous places in Silicon Valley that do this on an outsource basis. Typical costs are about $75 per IC. I can get some contacts for you if you'd like.

gary g.

[erik@nisene.com]

Decapping by hand is not only extremely dangerous, but it is done successfully by very few people. Nisene Technology Group Manufactures the equipment you would need to do this. Email me at erik@nisene.com and I will set you up with a quote and resources on getting out equipment.

[Grant Stockly]

The hard part is getting acid good enough. After an hour of work with some over-the-counter nitric acid I had a 68000 done, but the water content was so high that it left a residue on the chip. Its still fun to look at. MEFAS at $35-40 is worth it for sure!

[elrob1981]

Guys,

I just joined this forum and would really appreicate your help here.

What are the concentrations of the sulfuric and nitric acids you use for
wet chemical decapsulation. I'm in the process of purchasing chemicals for our chemical lab and need to know the concentration of acid in the solution that will yield the best results. I was thinking 90% Nitric Acid and 96% sulfuric acid would be ok to use but need you to confirm.

thank you

Roberto

[erik@nisene.com]

Originally Posted by elrob1981

Guys,

I just joined this forum and would really appreicate your help here.

What are the concentrations of the sulfuric and nitric acids you use for
wet chemical decapsulation. I'm in the process of purchasing chemicals for our chemical lab and need to know the concentration of acid in the solution that will yield the best results. I was thinking 90% Nitric Acid and 96% sulfuric acid would be ok to use but need you to confirm.

thank you

Roberto

There are several variations of sulfuric and nitric acid on the market. Our equipment uses 20% fuming sulfuric and 98% fuming nitric. I could give you a few pointers if you would like to discuss further. erik@nisene.com or 831-761-7980