David

Contrary to your view, we have a water based acrylic coating that has
been tested successfully to 200 DegC - that's 392 Deg F.

As to the original question, Jim, I am not sure that the coating will
achieve what you might be looking for, because the coating is not a very
good thermal insulator. So your components will need to be able to work
at the elevated temp - and the coating, such as the one I mention, will
certainly help.

Regards Graham Naisbitt

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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Douthit
Sent: Wednesday, April 24, 2002 17:34
To: [log in to unmask]
Subject: Re: [TN] TEMP EXTREME


James,

How about acrylic conformal coating?
You are so far above the Tg of acrylics that the coating can "flow",
melt, evaporate, or all the above!
(Not to mention letting contaminants reach the surface!)


David A. Douthit
Manager
LoCan LLC



"Marsico, James" wrote:


Hello Technet:

I think I may have asked this question a while ago (or something
similar)
but couldn't find anything in the archives.  I have a surface mount
assembly
that gets installed into a top assembly housing, with covers.  The test
guys
want to subject this assembly to 125 degrees C for 112 hours.  Assuming
that
all of the components are rated for this temperature, is there anything
else
that says this isn't a good idea?  I'm thinking about the solder joints,

maybe decreased reliability due to excessive grain growth?  How about
acrylic conformal coating?  The PWB is polyimide, so this shouldn't be
an
issue.  Anything else?


Thanks again...


Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879


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