| abstract |
An electrical substrate material is presented comprising a resin matrix which includes a thermosetting polybutadiene or polyisoprene resin, an ethylene propylene rubber, and optionally a thermoplastic unsaturated butadiene- or isoprene-containing polymer; a particulate filler, a flame retardant additive, a curing agent, and a woven or unwoven fabric. The presence of the ethylene propylene rubber enhances the heat age properties of the substrate material, particularly the dielectric strength and the mechanical properties, while other electrical, chemical, and mechanical properties of the material are not adversely effected. |