Barry,
  I am replying for our conformal coat engineer Ben Guthrie: e-mail:
[log in to unmask]

Given this problem, MTBF will surely be affected by coating, and actual
service costs will be affected, too.
  Try coating the whole thing with acrylic. easy to rework, negligible RF
performance impact, and gives some good protection. Another option is to
modularize the two "camps"-- make the uncoated section easy to replace as a
module on the coated board.
Ben.


At 03:16 PM 9/19/96 -0400, you wrote:
>I also will be grateful for some conformal coating advice 
>on an issue related to the current thread.
>
>We have a product that goes into aircraft with a 
>combination of digital and RF circuitry.  We are arguing 
>about conformal coating -- there are several RF parts 
>affecting about half of the board surface that cannot be 
>coated for performance and serviceability reasons.
>
>Based on this, we want to drop the conformal coating 
>because only half the board can be protected anyway.  
>The "other" camp argues that a half-coated board is better 
>than nothing.  The cost to mask the board is significant.
>
>Anyone deal with this issue before?  The main environmental 
>problems for this product are fungus and moisture. 

>Barry Allen
>SED Systems Inc.
>[log in to unmask]
>
>

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