Larry and all TechNetters

A Solder Mask / Resist, is a permanent product to do a temporary job - to
resist soldering!

A Conformal Coating is a permanent product to do a permanent job - to protect
the circuit ASSEMBLY not only the board!

Further, Resists are usually epoxy which is inherently more hydroscopic than
other polymers.

I intend posting a more descriptive explanation after a good nights sleep....

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 Larry J. Fisher
Sent:   Monday, November 24, 1997 4:16 PM
To:     [log in to unmask]
Subject:        Re: [TN] ASSY:  Soldermask vs conformal coat

In a practical sense, solder mask alone may not give you the protection you
need if your PWB assembly ends up in high temperature/humidity and/or
corrosive environment. Enen though the solder mask will protect all your
circuits in a harsh enviroment, you will still have metallic solder joints
exposed. Therefore, you would run the risk of shorting, the metallic circuits
reacting with the corrosive materials, etrc.

Conformal coatings were developed to completely seal the printed wiring board
assembly after all the components were soldered or joined in place. At this
point, the protective conformal coating covers everything and there are no
conductors exposed to the environment.

Hope this helps

Larry Fisher
Dexter Electronic Materials
[log in to unmask]

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