Consider the PTFE material from W.L. Gore

Very low moisture absorption if I remember correctly and good dimensional 
properties too.

Chuck Brummer
3M Manufacturing Engineer
8357 Canoga Ave.
Canoga Park, CA 91304-2605
(818) 734-4930




Dan Skweres <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
08/13/2007 12:25 PM
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Subject
[TN] Another Request.






Fellow Technetters,
I have another request from a customer that I do not have an immediate 
answer(s) for. Once again I was hoping that with the wealth of knowledge 
you collectively have that perhaps you could assist me in assisting my 
customer. They need a circuit board that...

  a.. Will reside within a float assembly of a gyroscope. 
  b.. The environment will consist of hydrogen with trace helium. 
  c.. A concern is the moisture absorption or adsorption, the hygroscopic 
properties, of the circuit materials used in the stackup. 
 They're searching for materials with extremely low coefficients of 
hygroscopic expansion and contraction, CHE and CHC.  The board needs to 
maintain stable electrical, mechanical and dimensional properties. Is it 
generally better to go with a rigid design rather than a flex design when 
concerned with the affects of ambient moisture?

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