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Help!

The Engelmaier equations used to estimate cycles to 
failure for leadless SMT components has, obviously, as 
one of it's terms the CTE of the printed wiring board.  I 
have been unable to obtain information on CTE of printed 
circuit boards, at least with any confidence, and 
measuring the CTE after build is too late in the product 
development cycle.  This is cirtical to our applications 
due to the long thermal cycling requirements of some of 
our programs (7-15 years).

The CTE of the board is effected by:
Base Material (Kevlar, Polyimide, G10)
Resin
Materal Lot
Layer count
Amount of copper (planes)
Heatsink bonding
Heatsink bonding material (epoxy, acrylic, thermabond)
Heatsink material (aluminum, copper)

1.  Has anyone done any testing on CTE of boards as a 
function of the above?

2.  Are there any equations which can be used to predict 
the CTE of the board and/or heatsink combination?

3. Is there any data on the CTE of boards besides the 
ranges I have seen in the text books.

I am considering running an experiment to determine the 
effects of these parameters.  Would anyone be interested 
in the data and of course help support the effort with 
boards, heatsink and bonding?


Jim Faris
AlliedSignal Aerospace
Guidance & Control Systems
(201) 393-3779