Abstract: A polymeric acid is synthesized by the ring-opening poly-addition reaction using a biphenyl tetracarboxylic acid as a tetracarboxylic acid moiety and an aromatic diamine, particularly p-phenylene diamine, as a diamine moiety. An aromatic polyimide resin layer possessing a highly desirable heat-resisting property as a heat-resistant insulating coating material and excelling in adhesive strength relative to a substrate is obtained by adjusting the polymeric acid in viscosity with a suitable organic solvent, applying the resultant polyamic acid on a substrate, and firing the applied layer of the polyamic acid. The substrate, for example, is a conductor layer formed as with copper and used as a multi-layer wiring board for hybrid IC's.

Abstract: A semiconductor device comprises a plurality of pellets fixed on a bed by a conductive adhesive agent, an insulating substrate having a junction wiring fixed on the bed between the semiconductor pellets, and wires for connecting the pellets and insulating substrate. The insulating substrate is fixed on the bed by an insulating adhesive agent including filling material such as particles of silicon dioxide and metal particles. The surfaces of the filling material particles are coated with an oxide film.

Abstract: A polyamic acid is synthesized by the ring-opening poly-addition reaction using a biphenyl tetracarboxylic acid as a tetracarboxylic acid moiety and an aromatic diamine, particularly p-phenylene diamine, as a diamine moiety. An aromatic polyimide resin layer possessing a highly desirable heat-resisting property as a heat-resistant insulating coating material and excelling in adhesive strength relative to a substrate is obtained by adjusting the polyamic acid in viscosity with a suitable organic solvent, applying the resultant polyamic acid on a substrate, and firing the applied layer of the polyamic acid. The substrate, for example, is a conductor layer formed as with copper and used as a multi-layer wiring board for hybrid IC's.

Abstract: An electric implement having a combination of insulation coverages comprising a thermosetting resin impregnated in an insulation layer wound about the electric implement, and a photohardening resin deposited over the impregnated thermosetting resin. A method of electrically insulating the electric implement, comprising impregnating the insulation layer with a thermosetting resin in vacuum; depositing a photohardening resin on the exposed portion of the thermosetting resin layer; photopolymerizing the photohardening resin; and thermosetting the impregnated thermosetting resin.