Insulating resin composition for multilayer printed wiring boards, multilayer printed wiring boards made by using the composition and process for the production thereof

The present invention relates to an insulating resin composition, comprising: a thermosetting resin, a thermoplastic resin, and a filler, wherein the cured product of the resin composition having a micro phase-separated structure, and the packing non-uniformly distributed in the rich thermosetting resin phase and Rich one phase of the thermoplastic resin. The composition may be prepared by high heat resistance, toughness, thermal deformation, and the wiring is good adhesion of copper, and the insulating layer can be formed of a fine patterning.