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