"N_Cook" writes:

Sam Goldwasser wrote in message
...
Bruce Esquibel writes:

In sci.electronics.repair Sam Goldwasser
wrote:

This type is usually dark gray and soft - about the consistency of a
pencil
eraser, maybe a bit tougher. It can be removed laboriously with
knives,
picks, and elbow grease. But the question is whether there is some
easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt
glue.

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard chemical
list by now but I believe the main purpose of it was to attack something
in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the bodies
would flake off but I don't remember anything else. Even ic's (chips)
that I
thought had some epoxy holding them together were no worse for wear even
soaking in the stuff.

Yeah, for the real application I have in mind, this is probably going to
take about 1,423 years (give or take a century).

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

Thanks.

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/

-bruce


Can you make a pilot hole with a thin steel rod, chisel ground at the end.
Then pass through it one of those carbide covered wire saw , garotte type
things, or even a coping saw blade, kept under tension. Would some scratch
damage matter? If so then perhaps spaced , glued-on, guard rings along the
blade

That's sort of what I've been doing, and have been contemplating making
a tool that is more matched to the job than the strips of aluminum and
other random items I've been using.

I'm coming to believe that any chemical approach will take to long, not
to mention the mess and health issues.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

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