It depends on the size of components, the board design, environment, MTBF
etc. Non-woven Aramid type materials are not that low in expansion. A good
design with 1/2oz Cu and few layers will approach a CTE of 10. For aircraft
engine control systems (engine mounted), which is my area of involvement, a
CTE of 10 is not good enough for long term reliability (45k hrs MTBF) with
anything bigger than a 20 or at a push 28 I/O LCC component unless you use a
low CTE core AlSiC for example or build CIC into the structure.
Ian Fox
TRW AS
-----Original Message-----
From: Marsico, James [mailto:[log in to unmask]]
Sent: 08 April 2002 15:43
To: [log in to unmask]
Subject: [TN] Military Designs
Good day, Technet:
Years ago, if one wanted to keep abreast of the latest and greatest designs
and assembly technologies for high reliability military applications, one
would attend the yearly seminars at China Lake. What conferences would be
recommended nowadays?
Also, if I may be so bold as to address a previous topic (chuckle, chuckle),
with regard to restraining core technology for military products, (Leadless
ceramic components , conduction heat dissipation, etc.) it seems that the
consensus for new designs would be to use a low TCE laminate (Thermount?)
with a compliant bond to an aluminum core. For you military folks, agree or
disagree?
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
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