Another source would be the EMPF publication EMPF TP200104 - Tips on
Conformal Coating (April 2001).
Kat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas O. Pauls
Sent: Wednesday, January 02, 2008 10:16 AM
To: [log in to unmask]
Subject: Re: [TN] Looking for Coating Comparison
Happy New Year Bill,
Some of what you are looking for can be found in the IPC-HDBK-830, the
Conformal Coating Handbook. I have copied section 8.4.4 on application
methods below. There are sections on each of the various coating
application methods in that Handbook which go into greater detail. Graham
Naisbitt, who does a great deal more work in dip coating than I do, may
have a more succinct summary.
Doug Pauls
Rockwell Collins
8.4.4 Application Method
Automated or selective applications can coat down to 0.025 mm [1 mil]
minimum in many applications, while more coverage is easily achievable,
even beyond 0.20 mm [8 mil] in a single pass. Manual applications
(brushing, hand spray, aerosol) can also be utilized over a wide spectrum
of coating thickness, though this should be accomplished over multiple,
thinner applications. Part consistency over time can be difficult to
ensure in manual operations. In a dipping application, coating thickness
can be greater and is highly dependent upon immersion and withdrawal
speeds, coating viscosity, and solids content. A basic rule of thumb is
that the slower the withdrawal speed, the thinner the coating. When spray
coating, shadowing of components may prevent that surfaces beneath them
from being coated. Thus, any circuitry located beneath components may have
poor protection. When area array packages are used, spraying may no longer
be an acceptable application method. By using selective coating, extra
coating material may be added at critical locations. Also, a second
coating layer can be applied to get better coverage. Then, all sharp
points and edges should have been smoothed by the first layer.
Bill Kasprzak <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/02/2008 10:06 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Bill Kasprzak <[log in to unmask]>
To
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Subject
[TN] Looking for Coating Comparison
Happy New Year to one and all.
It sure was difficult this morning to start the old grind again. Well, I'm
thinking just 8 more years and I hope I can retire, so the end is in
sight.
I'm looking into whether there has ever been a comparison study done that
gives the pros and cons for conformal coating application. I'm sure there
has been because I remember reading about it. Right now I can't seem to
find any information on it.
Specifically, I'm looking for something that states that Dip coating
provides better coverage than Spray coating.
Any suggestions? Thanks in advance for any responses.
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