RE>ASSY: CONFORMAL COATING BGAs 6/26/97
Hi Jim,
We have some experience that you may find useful.
We coat our boards (which contain a variety of BGAs) with acrylic conformal
coating and they pass tests after exposure to Mil-Std 810E, Humidity,
Aggravated Conditions.
Note that our boards are not mil spec. The acrylic is sprayed on with
multiple passes at several different angles, but we really don't know for
sure if all joints are completely coated. The assumption is that they are,
since the coating is thin to start out with, and is thinned even more for use
in the spray. It spreads easily and should penetrate beneath even our 35 mm
PBGA which has a ~15 mil standoff.
We don't do anything as large as 625 balls, but my guess is that if you have
a good coating applicator, you should be able to pass this test, too.
Regards,
Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
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--------------------------------------
Date: 6/26/97 12:23 PM
To: Greg Bartlett
From: Jim Marsico 516-595-5879
Does anyone have any experience applying conformal coating on an assembly
which
contains BGA components? Is it necessary to ensure that all solder joints
are
coated? If so, how it it done and how is it verified?
My specifics are: Military contract
625 ceramic BGA
.030" stand-off
Acrylic coating
Any opinions will be welcome.
Thanks,
Jim Marsico
(516) 595-5879
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From: Jim Marsico 516-595-5879 <[log in to unmask]>
Subject: ASSY: CONFORMAL COATING BGAs
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