In a message dated 10/27/99 7:25:32 AM Central Standard Time,
[log in to unmask] writes:
> Hi TechNetters --
>
> Anyone got any ideas/experience with cleaning (nondestructively!!)
assembled
> PWBs that were exposed to an electrical fire? The boards are covered with
> soot and associated black gunk. They are conformal coated (urethane).
TIA.
>
> Sheila Smith, Marconi AES
Hi Sheila!
Sorry for the late reply, and I don't know if this will do any good...
I worked for a company that's no longer in existence, and experienced a fire.
We worked a saturday and the operator who was running our aqueous cleaner
(very old vintage), turned the pumps, blowers, and conveyer off when shutting
down for the day, but forgot to turn the water heaters off. The equipment
being as old as it was didn't have the safety components incorporated that
later equipment has (like a complete power down if the temps in the wash
water or rinse tanks exceeded a certain temperature), and proceeded to do a
self-destruct...melt down if you will. Boiled all the water out of all the
tanks and caught fire. Set off about 8 sprinkler-heads just above the
cleaner, but there was smoke damage all over the production floor.
Now this was back in the time when we all used freon to clean, and water
soluble was the next big thing (doesn't seem that long ago does it?) But we
ran all the finished/partially finished boards thru our Detrext freon
cleaner, retested the ones that we actually were testing, and informed our
customers of product we built that we didn't test of the problem that we had.
Surprisingly, we only had to scrap a rack of boards that was close to the end
of the cleaner that happened to get some melted poly on them (the cleaner was
a poly- plastic constructed...old vintage, don't take that to mean that
plastic cleaners are bad news).
All the black-gunk cleaned off, but ours weren't conformal coated either,
don't know that freon won't degrade the coating...also don't know that you
can get freon anymore (without paying an arm and a leg...probably two arms
and legs)...
I feel for ya' Sheila, as Smokie the Bear says; "Only you can prevent Forest
Fires..." which translates to any fire is no fun at all, no matter if it's
inna a forest, or on a production floor...
I know, I've been there...
-Steve Gregory-
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