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July 2008

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TechNet E-Mail Forum <[log in to unmask]>, Inge <[log in to unmask]>
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Tue, 22 Jul 2008 12:43:48 -0700
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Phil,

have you ever seen electronics from the war places like Iraq and Agfanistan? 
I got the task to create a cleaning procedure to save hundreds of advanced 
boards which were so contaminated with sand, that you could just see the 
contours of the components!  They were 1B31 coated. First, I poured desert 
sand on fresh boards and put them in a +60 Centigrade oven for a week. As I 
suspected, the sand particles adhered more and more to the softened coating. 
It seemed impossible to remove them. But I found, that a suitable tenside 
added to ordinary tap water loosened the particles that were on their way to 
be imbedded in the coating. So, we simply used a popular cleaner that is 
used in many kitchens, used warm water and a brush, and could wipe off 95% 
of the sand with a gentle brushing. Sometimes you are lucky with very simple 
methods.

Your combination of graphite and brass dust is really a bad situation, worst 
case, as I can see, but my home made method may be worth trying. The brushes 
we used were ESD safe, may not be necessary, but I insisted to buy such. The 
choice of brush depends on what you got on the boards.

http://www.gordonbrush.com/esd/di_900.htm

Inge


----- Original Message ----- 
From: "Phil Nutting" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, July 22, 2008 8:18 AM
Subject: [TN] Washing dirty conformally coated boards


Good morning,

We have some circuit boards that we coat with Chemtronics Konform AR, that 
when returned from the field need to be washed to remove the graphite/carbon 
and brass dust (it won't blow off).   Washing and rinsing at temperature 
tends to peel the conformal coating off.  The currently process is hand 
washing and rinsing, but it is a totally uncontrolled process.

I'm looking for recommendations for a more controlled process that is less 
likely to remove the coating.  I just want to get the dusty stuff off the 
board.  It looks I'm going to have to create a machine or controlled process 
the works at room temperature.

Phil

Note: All the information contained in this e-mail and its attachments is 
proprietary to Kaiser Systems, Inc. and it may not be reproduced without the 
prior written permission of sender.  If you have received this email in 
error, please immediately return it to sender and delete the copy you 
received.

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