Abstract: The film forming, photosensitive, heat-resistant resin composition comprising a varnish of a polyimide precursor having no photosensitivity in itself, a polymerizable monomer or oligomer compatible with said varnish and capable of providing a high-heat-resistant polymer upon being polymerized, and a polymerization initiator for said monomer or oligomer. The resin composition is useful for the production of circuit substrates and semiconductor devices for high-density mounting including multi-chip modules or the like, such as printed circuits, printed boards, wiring boards and electronic components, since it can effectively avoid a reduction of the layer thickness during the film formation, and ensures a low cost production process. The pattern formation process using the such resin composition is also disclosed.

Abstract: A method for forming a photosensitive, heat-resistant resin composition film including the step of coating a base material with a varnish made up of a polyimide precursor having no photosensitivity, a photopolymerizable monomer or oligomer capable of providing a high-heat-resistant polymer upon being polymerized, and a polymerization initiator for the monomer or oligomer. The coating is exposed to a light pattern to polymerize the monomer or oligomer in a pattern. The remaining coating is selectively removed from the non-patterned areas. The patterned coating is heat treated to cure the polyimide precursor, thereby forming the film.

Abstract: A film forming, photosensitive, heat-resistant resin composition including a varnish of a polyimide precursor having no photosensitivity in itself, a polymeriziable monomer or oligomer compatible with the varnish and capable of providing a high-heat-resistant polymer upon being polymerized, and a polymerization initiator for the monomer or oligomer. The resin composition is useful for the production of circuit substrates and semiconductor devices for high-density mounting, since it can effectively avoid a reduction of the layer thickness during film formation, and ensures a low cost production process. The pattern formation process using such a resin composition is also disclosed. The polymeric composite having a particles-in-matrix microstructure and the production process thereof are also disclosed.

Abstract: A circuit board comprising a core material made from magnesium, a magnesium alloy, or a magnesium-based composite material, and an electric circuit formed on the core material. A process for producing the circuit board comprises the steps of (1) forming an electrodeposition-painted coating on such a core material, (2) forming a polyimide resin coating on the electrodeposition-painted coating, (3) forming a via hole extending through the resin coating to the underlying electrodeposition-painted coating, (4) etching and removing the electrodeposition-painted coating in the region exposed in the bottom of the via hole while masking the other region with the resin coating thereby extending the via hole to the core material, (5) forming a metal film on at least a free surface of the resin coating and an inner surface of the extended via hole, and (6) etching the metal film by using a photoresist mask to form a conductor layer having a predetermined pattern.

Abstract: A via hole structure for interlayer connection formed in an insulating film and a process for the formation of the same. Via holes are formed in an insulating film of a multilayer interconnected board or the like so as to have a shape such that when a metallic film for wiring is formed on the insulating film, the metal film can completely fill up the via holes. The via holes are formed by gradually increasing from the bottom toward the top of an insulating layer 8 the apertures of the via holes 7 formed in the insulating layer 8, comprised of a plurality of insulating resin film or photosensitive insulating resin film layers 2, 5, in a multilayer interconnected board comprising the insulating layer 8 laminated alternately with a wiring layer 13 comprised of an electric conductor.

Abstract: A circuit board comprising: a core material made from magnesium, a magnesium alloy, or a magnesium-based composite material, and an electric circuit formed on the core material. A process for producing the circuit board comprises the steps of (1) forming an electrodeposition-painted coating on such a core material, (2) forming a polyimide resin coating on the electrodeposition-painted coating, (3) forming a via hole extending through the resin coating to the underlying electrodeposition-painted coating, (4) etching and removing the electrodeposition-painted coating in the region exposed in the bottom of the via hole while masking the other region with the resin coating thereby extending the via hole to the core material, (5) forming a metal film on at least a free surface of the resin coating and an inner surface of the extended via hole, and (6) etching the metal film by using a photoresist mask to form a conductor layer having a predetermined pattern.

Abstract: A magnesium-based composite material having improved mechanical strength, and in particular an improved modulus of elasticity, and a relatively low density. The material is provided by pressing and sintering a mixture of magnesium or magnesium-based alloy particles or a particulate combination of magnesium particles and particles of one or more additional metals, with a reinforcement additive of boron, or boron-coated B.sub.4 C, Si.sub.3 N.sub.4, SiC, Al.sub.2 O.sub.3 or MgO particles.