From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem
Subject: Re: Atomic Force Microscopy Probes
Date: Mon, 22 Sep 1997 20:28:49 GMT

Richard <r.m.day@cranfield.ac.uk> wrote:
>I have stuck a silicon block with a tiny afm probe jutting out
>from one end onto a small stainless steel mounting using epoxy resin.
>Does anybody know a good solvent to melt the glue so I can remove the
>silicon block (with the broken tip!) from the steel mounting
>I have already tried Acetone, Chloroform and Isopropanol however this
>doesnt do the trick.

In my experience, the best solvent is warm N,N-dimethylformamide,
but some people use 1-Methyl-2-pyrrolidinone. The higher the
temperature, the faster the attack, and temperatures over 100C
can be used. Most common solvents will not attack epoxy.

Fine jets of hot, concentrated inorganic nitric or sulfuric
acid are used to remove epoxy packaging from ICs, and if you
aren't worried about the metal, aqua regia is another option.

All the above are hazardous, read the MSDS carefully, and ensure
that you use appropriate protective equipment and ventilation.

       Bruce Hamilton

From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.chem,sci.electronics
Subject: Re: Encapsulating material removal
Summary: Not an easy task!
Keywords: encapsulating agents, solvents
Date: 8 Jul 91 03:53:53 GMT

In article <1991Jul1.132148.359@mof.govt.nz> crookb@mof.govt.nz writes:
>Can someone help with information on a known method to non-destructively
>remove the various encapulation materials used to protect electronic 
>components.

	Unfortunately, "non-destructive" removal of encapsulating materials
is often an oxymoron.  Solvents and chemical reagents which will attack
the encapsulating material may often attack the interior components.

	It is necessary to know something about the composition of the
encapsulating material in order to intelligently select a solvent or a
reagent for direct chemical attack.  Unfortunately, most suitable solvents
and reagents are flammable or otherwise hazardous to handle.

	I will list some example solvents and reagents that I have
personally used for this purpose; however, I would urge *extreme* caution
before actually trying any of these chemicals!  Use of these materials
should be in a laboratory environment in a fume hood - certainly not in
a home environment!

1.  methyl ethyl ketone - readily available, but often ineffective

2.  dimethylformamide (DMF) - great stuff, but hazardous!

3.  cyclohexanone

4.  cyclohexanol - will attack some phenolics, not an easy feat

5.  methylene chloride - commonly sold as a paint stripper

6.  carbon disulfide - extremely flammable

7.  diethyltoluamide - great stuff, but hazardous!

8.  trichloroethylene

9.  ethylbenzene

10. dioxane

11. chlorobenzene

12. aniline - one of the few reagents that will attack polyimides and epoxies

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635   [note: ub=acsu.buffalo.edu] uunet!/      \aerion!larry

From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem,alt.fan.cecil-adams
Subject: Re: Dissolving epoxy
Date: Wed, 12 May 1999 08:41:02 +1300

In article <7h9vc8$qs_008@camelot.ionet.net>
timtroyr.removethisbit@ionet.net (Tim Robinson) writes:

>Is there anything that will dissolve that ugly gray epoxy that was
>common many years ago?  It can't be something that will damage the wood.

Dimethylformamide is about the only solvent I know of that dissolves epoxy
at a speed likely to be effective in a normal lifetime. However, DMF is very
likely to damage the wood, and I would not use it on a potentially-valuable
item.

My experience has been that some chemical adhesives, such as epoxy on
heat-sensitive, porous material, are best attacked by mechanical means.
I'd recommend a gentle, patient, approach with a fine wire file to cut through
the epoxy, followed by other abrasives ( such as 600-1000 grit paper ) to
remove the residual epoxy. Depending on the adhesive and wood types, the
epoxy may harder than the wood, so care is needed.

    Bruce Hamilton

From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem
Subject: Re: Dissolving integrated circuit packages
Date: Sun, 19 Sep 1999 17:41:30 GMT

yurigagarine@my-deja.com wrote:

>I'm trying to remove the plastic package of an integrated circuit. Does
>anybody know of a solvent easy to find that would do this?.

There have been several threads in sci.chem, sci.electronics.*
and sci.engr.semiconductor over the years. Search Dejanews
for solvent/removal and epoxy and IC in the sci.* groups.

Most of the plastics used for ICs are epoxys that aren't attacked
at an acceptable rate by any organic solvent, including DMF
( dimethylformamide ) and NMP ( N-methyl-2-pyrrolidone ), the
solvents often used for less robust epoxys.

The most common "solvents" for IC encapsulating epoxy appear
to be fuming nitric acid ( sometimes warmed ! ) and hot
concentrated sulphuric acid ( often boiling - although I recall
a poster reporting that they used a special device that fired a
very fine jet of sulphuric acid at near 300C at the chip
packaging which could remove the epoxy without heating the rest
of the chip significantly ).

Others have used a beaker and immersed the complete chip in the
acid and brought to near boiling ( about 280C, over about 330C
the acid may start decomposing ). Obviously, the chip is
unlikely to work again.

These acid techniques require special fume systems and heaps of
personal protective equipment. There have also been claims
that you can grind off most of the plastic and then heat on
a hot plate to degrade the remaining epoxy, which becomes
rubbery - I suspect the fumes will be very noxious as well,
and the result rather messy.

          Bruce Hamilton

From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem
Subject: Re: epoxy and gasoline
Date: Fri, 9 Oct 1998 08:22:41 +12

In article <361BB385.6362@ONLINE.NO>
 "L. Smith" <LARRYS@ONLINE.NO> writes:

>Lee K. Gleason wrote:
>>   Is epoxy a good choice for something that will be immersed in
>> gasoline and heated continually (well, the carb doesn't get real hot,
>> but under hood temps ain't room temperature)? Any particular kind of epoxy
>> better than others for this application?

Ciba Geigy ( Araldite ) make various grades of epogy, some are claimed
to be more fuel resistant that others. Hod rodders probably tinker with
their systems frequently, so the poor durability ( months to years -
compared to 10-15 year original design life ) probably isn't a problem.

An experienced mechanic could suggest alternative products, but
the best solution is usually a plug of resistant metal or plastic
( usually an engineering plastic, such as Delrin ), drilled out,
and theaded/shrunk/glued in.

>Yes, epoxy tolerates gasoline pretty well.

Not in my experience, especially in the carburettor, when it is
subjected to thermal cycles up to 50C in the heat soak period
after an engine has been turned off. We investigated Araldite
and other epoxys as a means of solving a compatibility
problem with oxygenated fuels, they swelled, then broke away
from the surface of test pieces after a few week of immersion,
regardless of substrate or surface preparation. They would not
be a good long-term choice for critical orifices.

>Essentially most commonly available epoxy resins are similar and are
>based on bisphenol A diepoxide.
>The second part - the hardening agent or catalyst - has  many different
>variations and it is this part that most often affects the ultimate
>hardness or toughness of the cured resin.

That doesn't make it resistant to gasoline, which can be a complex
mixture of hydrocarbons and oxygenates - which play havoc
with many common polymers, including Araldite.

>Araldite is a common brand name over here, and I believe it is available
>in the USA also.  They should have a quality product that will work for
>you.

Given the widely-different formulations of Araldite ( Ciba Geigy offer
free brochures on the chemical compatibility of their products ), and
the widely different composition of US fuels, if the orifice is critical,
and intended to be permanent, I would go with one of the more
long-term drilled plug materials, fixed in the method suggested
by the manufacturer or an experienced mechanic.

          Bruce Hamilton