Abstract: Method of printed circuit board manufacture, and resulting board. A plurality of prepreg sheets composed of ceramic paper and containing different quantities of a resin are laid on each side of a core metal sheet having a through hole. A copper foil is laid on the prepreg sheets on each side of the core. All of the layers are pressed together under heat to make a metal-core printed wiring board. The prepreg sheets form an insulating layer having a high heat-dissipating capacity on each side of the core and a reliable insulator in its through hole. The ceramic paper consists essentially of short ceramic fibers having a diameter not exceeding fiber microns and a length of 5 to 500 microns, and contains 3 to 10% by weight of microfibrillated cellulose fibers as a binder for the ceramic fibers.

Abstract: Inorganic paper, which is made through paper-making process from a mixture consisting essentially of:(a) fibrous inorganic compound, as the principal component, having a fiber diameter of 100 microns or smaller and a fiber length which is ten times or more as long as the fiber diameter; and(b) fiber material in a microfibrillar form as a binding agent.

Abstract: To manufacture a steering wheel rim, a sleeve 21 is formed by a braiding machine 12 by interlacing and braiding unidirectional fibers 10. A coil-shaped lightweight core 9 is then inserted by a covering apparatus 14 into the braided sleeve, and core rings are cut out from the coil. The ends of the cut rings are butted to form the rims, and after being joined with a spoke 2 are placed in a mold 31, where an outer molded layer 11 is formed by injecting a thermosetting resin into the mold and heat curing it.

Abstract: A heat conductive circuit board includes an insulating layer provided on a metal substrate, and an electrically conductive metal foil formed on the insulating layer, and the insulating layer is formed by impregnating an alumina paper with organic polymer. The alumina paper is made by subjecting a material containing alumina fiber as the principal components to a paper-making process. The insulating layer has excellent properties of heat transfer not only in the thickness direction but also in the surface direction, and thus, the heat conductive circuit board is excellent in heat dissipation properties.

Abstract: A superconducting solenoid designed to improve working efficiency, heat resistance and electrical insulation of the solenoid to a practical extent. The superconducting solenoid comprises a winding frame, wires formed of filamentary conductors having superconductivity and wound around the winding frame, an insulator formed of alumina fiber material and covering each of the wires for providing electrical insulation, and a resinous material impregnated in between turns of the wires so as to provide a supporting structure. The insulator formed of alumina fiber material is in the form of a sheet, a mat or a yarn.

Abstract: A laminated board lined with thermally and electrically conductive material, which comprises:(a) a prepreg sheet formed of an alumina paper made from a mixture of alumina fibril, as the principal component, having a fiber diameter of 100 microns or smaller and a fiber length which is ten times or more as long as the fiber diameter, and microfibrillar organic fiber as a binding agent, and a thermosetting resin; and(b) an electrically conductive material in foil such as copper or aluminum bonded to said prepreg sheet.

Abstract: A submergible motor for use in a well of water, for example, comprises a motor winding, an insulated power supply conductor for connection to a power supply, an insulated motor conductor connected to the motor winding, and a circuit element electrically connected between the power supply and motor conductors, the circuit element being encased in a molded material in a water-resistant manner and connected to the power supply and/or motor conductors.

Abstract: A flame retardant liquid rubber composition comprises a hydrogenated polyhydroxybutadiene polymer and castor oil, which are modified with an isocyanate having the formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 respectively represent a lower alkyl group or hydrogen atom and n is an integer of 1 to 4, and alumina hydrate and magnesium hydroxide. The castor oil can be incorporated before adding said isocyanate or can be converted into an isocyanate prepolymer by reacting with said isocyanate before the addition.