Jim

One observation is that you SHOULD be able to effect a spot repair by
soldering thru the coating.

Make sure that your soldering is hot and that you have some exhaust / fume
extraction to the rework area. The coating should then be effectively
vaporised with minimal bi-products. Do be careful if the product has
Isocyanates.

Otherwise the supplier should have some proprietary stripping compound. We do!
We also make a conformal coating stripping system which uses solvents to
effect removal. If you would like more, the  please let me know

Graham Naisbitt


Concoat Ltd                                     Email: [log in to unmask]
Alasan House, Albany Park                       Tel:    +44 (0)1276 691100
Camberley, Surrey GU15 2PL UK           Fax:    +44 (0)1276 691227


-----Original Message-----
From:   TechNet  On Behalf Of Jim Marsico 516-595-5879
Sent:   Wednesday, October 29, 1997 6:01 PM
To:     [log in to unmask]
Subject:        Re: [TN] CONFORMAL COATING REPAIR

We occasionally have to spot remove polyurethane coating, mostly to remove and
replace a component.  It's not easy, but we use DMF (Dimethylformanide).  A
small piece of cotton cloth is cut to the size of the coating which needs to
be
removed, the cloth is saturated in DMF and placed on the board and presses in
place to make good contact.  As the DMF slowly attacks the coating, the cloth
is removed and replaced with a fresh saturated piece.  This process is
repeated
until all visible signs of coating are removed.  One word of caution, though,
DMF will attack the solder mask and even the epoxy in the PWB if left on long
enough.

Jim Marsico
(516) 595-5879
[log in to unmask]

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