Abstract: A thermoplastic composite material is presented which comprises a thermoplastic matrix which is highly filled with a coated ceramic filler. In an important feature of the present invention, the ceramic filler has been coated with a rubbery polymer that bonds to the filler. In a preferred embodiment, the thermoplastic matrix comprises a fluoropolymer, preferably a chlorofluoropolymer and the ceramic filler is a fused amorphous silica coated with a rubbery polymeric material. The thermoplastic composite material of this invention exhibits numerous advantages which makes it well suited for use as a bonding film, particularly a bonding film for producing multilayer printed wiring boards.

Abstract: 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.