Xref: utzoo comp.lsi:1052 sci.electronics:12222
Path: utzoo!utgpu!watserv1!watmath!att!cbnewsl!tomcat
From: tomcat@cbnewsl.att.com (fred.j.shubert)
Newsgroups: comp.lsi,sci.electronics
Subject: Re: reverse engineering
Summary: reverse engineering requires the proper acid !!
Keywords: epoxy removal
Message-ID: <1990Jun4.171212.22994@cbnewsl.att.com>
Date: 4 Jun 90 17:12:12 GMT
References: <778@fornax.UUCP>
Followup-To: poster
Distribution: na
Organization: AT&T Bell Laboratories
Lines: 46

In article <778@fornax.UUCP>, donaldo@fornax.UUCP (Don Smith) writes:
> I would like to reverse engineer a calculator watch but am having
> a hard time removing the epoxy coating the chip.  So far I have 
> tried a number of chemicals including: 
> 
>    acetone
>    and hydrochloric acid.
 



A while back I did RE on a number of devices.  I got to the point that
I could still run the chip _after_ opening it (DIPs).  If the metallization
on the chip is alumunim (you probably don't know) then you want to use
boiling 99.99% sulfuric acid.  WARNING!!!!!  This is NASTY shit.  Acids
will not open these epoxied devices unless it or th eacis is hot.  You
can heat the part to >200 degrees F and use an eyedropper to SLOWLY
etch away the epoxy.  As the epoxy etches off, rinse with isopropanol
(off the hot plate) and air dry.  Then continue the process until you see
silicon.  If the metallization is gold, use boiling fuming nitric acid
and the same process.   Remember, this is VERY DANGEROUS AND I REALLY
RECOMMEND YOU DON'T RISK LOSING YOUR SIGHT, FINGERS, OR LIFE TO LOOK
AT A CALCULATOR CHIP.  THIS TYPE OF WORK BELONGS IN THE LAB USING
APPROPRIATE EQUIPMENT OBSERVING THE PROPER LABORATORY SAFETY PROCEDURES.
I PROVIDED THIS INFO TO SHOW YOU THAT YOU ARE REALLY MESSING WITH FIRE!!

     
If you really want to discuss this further, E-mail me and have a
company or college chemistry lab and supervision available.  Then
we can talk.



______________________________________________________________________________
Fred J. Shubert         | "You haven't lived until you've seen a 'cat fly!!!"
AT&T Bell Labs          |-----------------------------------------------------
Whippany, N.J.          | DISCLAIMER:  All views are that of my own. PERIOD.
Ma-Bell 201-386-3094    |              Who else could be so 'cat crazy!!

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