Coaxial cable insulation and coaxial cable made therewith

摘要

A ceramic filled fluoropolymer composite coaxial cable insulation and the coaxial cable made therefrom is presented. In accordance with the present invention, the coaxial cable insulation is comprised of 60-25% fluoropolymer that is fibrillatable, 40-75% ceramic filler and a void content which is effective to provide a dielectric constant of approximately less than 2.30. In a preferred embodiment of the present invention, the coaxial cable insulative composite comprises approximately 40 weight percent PTFE, 60 weight percent fused amorphus silica and a void volume percent of between 30 and 60. Also in certain preferred embodiemnts, the composite may include 1-4% by weight of microfiberglass filler and the ceramic filler may be coated with a silane coating. The provision of the void volume is an important feature of the present invention and acts to substantially lower the overall dielectric constant of the insulative composite. Still another important feature of this invention is the provision of an effective amount of ceramic filler (silica) so as to reduce the coefficient of thermal expansion (CTE) to a CTE approximating that of copper. This results in a coaxial cable having electrical properties which are more temperature stable than the prior art; and coaxial cable assemblies having improved thermomechanical stability relative to the prior art.