Regarding the CTE value for aramid fiber, it is most often listed as -2 ppm/C
in the x,y and around 60 ppm for the z-axis.  I should mention that the CTE
value of the reinforcement fiber is often very low when compared to the CTE
values for the resin system that can be a more dominate factor (especially the
z-axis).  The CTE value for copper is 14-16 ppm, 23 ppm for SnPb, so there is
a dog's breakfast of material CTEs to deal with before you make your decision
about the reinforcement material.
Your second question on technical papers and information sources for
controlled expansion materials and designs, I would suggest that you give Joe
Leibowitz at Shirline Composites a call.  He can be reached at 310-558-4888.
Joe has done work with carbon fiber as well as mixtures of aramid fiber,
carbon and quartz and has published and given several IPC technical papers on
this subject.

Regards,
Lyle Wallig

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