Abstract: This invention relates to a photo- or heat-curable resin composition which yields a cured product with minimal cracking and high reliability. The resin composition of this invention comprises 100 parts by weight of (A) photo- or heat-polymerizable unsaturated compound composed of a polycarboxylic acid adduct of bisphenol-epoxy (meth)acrylate , 10-100 parts by weight of (B) alkylene oxide-modified product of (meth)acrylate or oligomers thereof, 0-50 parts by weight of (C) compound containing epoxy group and 0-50 parts by weight of (D) photopolymerization initiator or sensitizer. The composition exhibits high heat resistance and good microfabrication quality and is useful as a peripheral material of electronic parts such as semiconductor devices by the build-up process, for example, as a material for forming insulation layers in multilayer printed wiring boards.

Abstract: This invention relates to a photo- or heat-curable resin composition which yields a cured product with minimal cracking and high reliability. The resin composition of this invention comprises 100 parts by weight of the resin-forming component containing a photo- or heat-polymerizable unsaturated compound and 0.01-5 parts by weight of an inorganic filler such as silica sol with its average particle diameter controlled in the range 5 nm-0.5 &mgr;m. The composition exhibits high heat resistance and good microfabrication quality and is useful as a peripheral material of electronic parts such as semiconductor devices by the build-up process, for example, as a material for forming insulation layers in multilayer printed wiring boards.

Abstract: A bundle of pitch-based carbon fibers which is composed of 1000 to 100,000 continuous fiber filaments having an average diameter of 4 to 8 .mu.m, a filament tensile strength of at least 3.0 GPa, and a modulus of at least 600 GPa, and also a method for producing a fine diameter pitch-based carbon fiber wherein use is made of a spinning nozzle with a single nozzle plate which has at least 1000 capillary holes, has the capillaries arranged concentrically and circularly in 3 to 20 rows, has the capillaries positioned to be divided into at least two blocks, has a columnar projection protruding at least 20 mm from the surface of the nozzle plate at the center of the nozzle plate, and has capillaries of a diameter of 50 to 110 .mu.m.