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From: donaldo@fornax.UUCP (Don Smith)
Newsgroups: comp.lsi,sci.electronics
Subject: reverse engineering
Keywords: epoxy removal
Message-ID: <778@fornax.UUCP>
Date: 1 Jun 90 23:22:23 GMT
Distribution: na
Lines: 12

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.

The hydochloric acid removed the epoxy but also damaged the chip. It
appears that the epoxy is a cross linked polymer structure which is
hard to break apart. I would appreciate the names of chemicals which
can break up cross linked polymers without damaging the chip.  The
watch is an inexpensive OEM type watch costing about $10.