Hi Susan!

Unfortunately I am forced to do this all of the time! It is very very
dirty.  We have a nice machine from Nicene for assisting with it--goes
for somewhere in the $50K range.

The only way to do this while the part is on the board is to very
carefully pick at it with a hot air jet and Xacto knife.  You will
probably whack the die some--if you machine away some of the encapsulant
first it is a bit better.  This will also probably burn your fingertips
a bit.  You obviously won't save the wirebonds.

If you take the part off of the board:

The sulfuric acid will generally eat the aluminum pads and any organic
passivation on top of the die.  The process is done at very high
temperatures (>200C).  The nitric acid is done at around 70C and will
preferentially attack copper.  Obviously the nitric is preferable but
some of the encapsulants refuse to succumb. 

If you don't have a nice decapsulator like we do, then you can do the
dipping by making a cute little nichrome basket and bending the device
leads into the mesh.  You of course need to do the process in a high
flow chemical hood, and I like to wear a supplied air respirator as a
backup.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Susan Hott
Sent: Thursday, October 11, 2007 2:21 PM
To: [log in to unmask]
Subject: Re: [TN] Dissolving SOIC casing

Thanks for the offer, but need to do it pretty quick here or farm out to
someone else.
Customer wants to see the die inside.

Susan


-----Original Message-----
From: R Sedlak <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 11 Oct 2007 1:55 pm
Subject: Re: [TN] Dissolving SOIC casing



Susan:
Why don't you send me one of these casings, and let me do some
experimenting, and give you a recommendation.

Rudy Sedlak
RD Chemical Company
1350 Pear Avenue
Mountain View CA 94043


Susan Hott <[log in to unmask]> wrote: Greetings to all I need to dissolve
the black "plastic" casing on an SOIC to see the die.? Does anyone know
what I can use to do this?

Thanks
Susan Mansilla Hott
Robisan Lab
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