The "non woven" materials may have low CTE numbers by themselves but I would
pay heed to the external layer CTE when layer below is a plane and separated
by .005.  The CTE goes up.  With the plane thickness being one or two ounce,
hold on.  It can be quite a bumpy ride.  The non wovens are not the end all
answer to dielectric (low CTE, high manufactuability) that I once hoped.  The
epoxy is nice relative to moisture... just watch out for Z expansion in
either material.

Brad