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

Philip Pemberton philpem at philpem.me.uk
Thu Oct 28 15:56:31 BST 2010

On Thu, 2010-10-28 at 00:40 -0700, Jason Flynn G7OCD wrote:
> Re: Acetone, I guess it was used for the 'soft' plastic of
> the smartcards and my feeling is that it would have little
> effect on the 'hard' case used on a typical DIP.

It won't even touch it.
Acetone is the active ingredient in a lot of solder flux removal

As I understand it, the casing on most ICs is a heat- and
chemical-resistant thermoset resin.

> I believe the active
> compound is methelene chloride and it's insanely volatile
> so you need a well ventalated area.

Methylene chloride is the active ingredient in Ambroid PRO-WELD plastic
welder (I've got a bottle of it in the cupboard). If memory serves, it
utterly destroys most plastics, but doesn't touch ICs. It's been a while
since I tried, though.

> It seems most PDIP mould compound materials are filled
> Epoxy, with the filler being a mineral or glass,
> therefore I think that one should go straight for the
> Rosin or debonder and skip the Acetone.

Something that attacked FR4 (epoxy-filled glass-fibre PCB substrate)
would probably do a respectable job on IC plastic...

I was going to suggest HCl+H2O2 (the Crazy Man's PCB Etchant) but I
suspect it won't be anywhere near strong enough (it doesn't really do
anything to FR4).

If you wanted to try sulphuric, you could probably grab some of that out
of an old-style car battery. Charge it to full, then stick a syringe
into the filler hole and suck some out. Hope you have a steady hand, and
that your life insurance covers "acts of unbelievable stupidity"...

philpem at philpem.me.uk

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