Date   : Thu, 28 Oct 2010 23:24:33 +0100
From   : list-a_cloud9.bbc-micro@... (Theo Markettos)
Subject: Reversing the Tube ULA (destructively)

In article <4CC9DB2D.50308@...> you wrote:
> Well, for your edification and delight, I tried an experiment a little 
> earlier this evening.  A small amount of concentrated sulphuric acid on 
> the top of an IC had no visible effect.  I also tried conc nitric (not 
> the same as fuming nitric) and conc hydrochloric, and for good measure 
> also a mixture of nitric and sulphuric (that's what you use to make 
> guncotton and nitroglycerine) and /aqua regia/ (the 1:3 mixture of conc 
> nitric and hydrochloric acids that is almost the only acid to dissolve 
> gold).  None of them made the slightest impression on an IC package at 
> room temperature.  The leads, yes.  The package, no.

How conc was your conc nitric?  FWIW our lab's decapsulation used fuming
98% nitric acid:
http://www.cl.cam.ac.uk/~mgk25/sc99-tamper.pdf

Theo