Jacob,

You may be unwise to apply a coating of any description to aged assemblies.
Please consider that coatings seal in as well as out.

You say that the corrosion is worse after repair which would be consistent
with flux residues left behind. Are you able to clean the re-worked area
effectively? You might want to try some of the new aerosol cleaning
materials such as those from TechSpray Inc Chemtronics(?) or perhaps
Electrolube, at least they will help to reduce the amount of residue.

Alternatively, why not try a no-clean low residue solder, that may help.

If you do use a coating, then an Acrylic would be ideal as it's easy to use,
fast to cure and solderable.

Graham Naisbitt
__________________________________________________________________________

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Concoat Ltd
Alasan House, Albany Park
Camberley GU15 2PL UK                        http://www.concoat.co.uk

Application Engineers in Chemical Compounds to the Electronics Industry

-----Original Message-----
From: Jacob Mozel <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 28 January 1998 12:45
Subject: [TN] Conformal coating


>Hi TechNet,
>
>I'm working for a big repair lab of cellular phones. For a long time we
>experience returning of many cellular phones due to corrosion, specially
>after repairing.
>I thought about using a conformal coating to protect the fresh solder
>from humidity and moisture.
>Does anyone has got an experience in this kind of work and could
>recommend easily removable coating (we do not seek solvent protection),
>the application method and curing mode (since there are expected many
>shaded points, UV or any radiation curing does not seem feasible).
>
>
>Thanks
>
>Jacob Mozel
>
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