To provide a composite material which comprises a filler, an adhesive, and a porous substrate and has various desired properties useful for electronic boards, chip packages and other electronic devices.

This composite adhesive material comprises: A nonwoven substrate having certain void volume and an average flow pore size; and a mixture containing an agglomerate of a filler particle and an adhesive, wherein the mixture is distributed evenly over the whole void volume of the substrate, the agglomerate defines the maximum particle size, the minimum particle size, and the average particle size, the ratio of the average flow pore size to the maximum particle size exceeds at least 0.7, or the ratio of the average flow pore size to the average particle size exceeds at least 1.4, or the ratio of the minimum pore size to the average particle size exceeds at least 0.8, or the ratio of the minimum pore size to the maximum particle size exceeds at least 0.4. Pref., the substrate comprises a fluoropolymer such as polytetrafluoroethylene.