We use exclusively use urethane and acrylic and have passed several military
(MIL-STD-810) salt fog and humidity tests. Our products run the gambit from
space hi rel to ground military to military avionics. We also have test results
that show urethanes gave better electrical insulation compared to paralyne for
very high impedance circuits.
The big secret to passing these types of tests are: Clean PWBs (No residual
solvents), good conformal coating, orienting the PWB so the moisture will not
condense on them, providing adequate drain holes to let the condensed liquid out
of the chassis, and to seal or move any cover chassis parting lines to prevent
moisture from running on to the PWBs.
Scott Newland
Harris GSCD
321 727 6472
Pager 321 690 4131
E-Mail [log in to unmask]
For a brain teaser try:
http://pao.gsfc.nasa.gov/science.html
-----Original Message-----
From: WEEKES, MICHAEL HS-SNS [mailto:[log in to unmask]]
Sent: Tuesday, December 17, 2002 4:07 PM
Subject: conformal coat survey
Can participants reply with the conformal coating they use, why they think
it's the best and why alternatives did not work out? PS: does anyone use
anything besides paralyne / paraxylene in order to pass salt fog or humidity
tests? Choices: silicone, paralyne, acrylic, epoxy, urethane. To be
honest, we'd love to ensure a rugged coating without the process horror and
non-reworkability of vapor deposition. Please include whether your product
operates in an aerospace, MIL, telecom, automotive, industrial,
agricultural, off-highway, etc. environment
thanks,
Mike Weekes
[log in to unmask]
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