[BBC-Micro] Reversing the Tube ULA (destructively)

Pete Turnbull pete at dunnington.plus.com
Thu Oct 28 19:52:17 BST 2010

Theo Markettos wrote:
> In article <AANLkTinf=3La8nf+0yhOe6XEBp-nZuh=7j-ExpcK7R3B at mail.gmail.com> you wrote:
>> That's great!  I see that acetone for the plastic and violinist's rosin for
>> epoxy is supposed to work
>> (http://s3cu14r.wordpress.com/2010/07/15/boiling-chips-in-tree-sap/)  - has
>> anyone tried it?
> I hadn't heard of this, but there's a number of chips I've been wanting to
> depackage so I may give it a go sometime.  Rosin is also used in soldering
> flux, so possibly a pot of plumber's flux might be another source.

As Ian said later, plumber's flux is a weak acid -- it used to be 
"killed spirits" which is zinc chloride solution, traditionally made by 
dissolving zinc granules in an excess of dilute hydrochloric.  Modern 
fluxes are a bit more sophisticated but basically (er, or acidically 
;-)) similar.  They have no effect on IC packages.  Nor does rosin.  The 
rosin in electronic soldering flux is the same stuff as used for violin 

The original note was about getting the die out of a plastic smartcard, 
and lots of solvents will do that, including acetone and MEK (methyl 
ethyl ketone).  Plastic Weld is methylene chloride, which is more active 
than either acetone or MEK, but none of them will dissolve an IC package.

Nor will battery acid, which is not especially concentrated sulphuric acid.

You really will need something like fuming nitric acid, I fear.  Try 
or http://www.siliconcert.com/decap.htm (the first two hits Google has 
for "dissolve IC package".

Pete						Peter Turnbull
						Network Manager
						University of York

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