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.