We've been using AR for military applications for over 25 years.  This
includes avionics, shipboard, and ground.  Usually, all of our
electronics are in an enclosure, and we had never had any reliability
problems.  We do have to use UR for space applications in order to meet
the outgassing requirements, and we use XY for applications where the
electronics may come in contact with jet fuel.  These are the exception
to the rule.  

Jim Marsico
EDO Corporation
1250 New Horizons Blvd.
North Amityville, NY 11701
631-630-5079
[log in to unmask]
 
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of - Bogert
Sent: Thursday, February 15, 2007 7:24 PM
To: [log in to unmask]
Subject: [TN] Using Type AR Conformal Coating

February 15, 2007

Folks, we have some military OEM'S that are switching from Type UR
conformal coating to Type AR.  The main reason for the switch is because
it is hard to remove Type UR coating in event of a rework, and certain
chemicals sold by the coating manufacturers for UR coating removal are
highly conductive and have caused problems since the cleaning process
did not adequately remove them.  The other reason is we wanted a coating
that could be easily removed in event product failed in the field so we
could do ATE to quickly find the source of the problem.  Our product is
used in a military application but it is contained in a cabinet that is
dust tight.  We have some assemblies that are not coated at all with no
known problems.

Do any of you folks use Type AR for military product, and if so, what
are your experiences using the coating?  I have heard about problems
using alcohol for coating removal since it goes where you do not want it
to go.  I have also heard that if a spray process is used, it takes 4 or
more passes on each side of the board to achieve the minimum J-STD-001
thickness.  At least one source indicated using AR may cause some solder
joint reliability issues.

Any info you have would be a help.  Thanks.

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