Abstract: The present invention relates generally to fiber-based reinforced composite sheets comprising one or more woven or non-woven para-aramid or fiberglass fabrics, sheets, or papers, impregnated with a polymeric matrix, said polymeric matrix comprising at least one polymer and a thermally conductive filler component suitable for conducting heat, the sheet being useful as a thermally conductive printed circuit board substrate or as a component in a thermally conductive integrated circuit chip package.

Abstract: The invention is directed to substrates for electronic circuitry. The substrates of the invention have a first polyimide layer having a functional filler and a second polyimide layer having a functional filler. The first layer is non-identical to the second layer, and a surface of the first layer is in contact with and is directly bonded to a surface of the second layer. Filler from each layer extends into the interface between the two layers, and a plurality of covalent bonds are present between the first and second functional layers that chemically bond the two layers together to provide a reliable, predictable multifunctional substrate for electronic circuitry with improved performance relative to polyimide layers bonded together by an adhesive.

Abstract: The invention is directed to substrates for electronic circuitry. The substrates of the invention have a first polyimide layer having a functional filler and a second polyimide layer having a functional filler. The first layer is non-identical to the second layer, and a surface of the first layer is in contact with and is directly bonded to a surface of the second layer. Filler from each layer extends into the interface between the two layers, and a plurality of covalent bonds are present between the first and second functional layers that chemically bond the two layers together to provide a reliable, predictable multifunctional substrate for electronic circuitry with improved performance relative to polyimide layers bonded together by an adhesive.