Abstract: The present invention relates to a solid printed substrate to be used for mounting electronic parts and a method of manufacturing the same. A metal base substrate having a plurality of copper foil layers stacked thereon is employed placing a thermoplastic polyimide sheet between each copper foil. The metal base substrate with a circuit pattern prepared on each copper foil layer is processed by bending or deep drawing into a box-shaped work which has an opening surface. The opening surface is processed so as to have a substantially equal area with that of the bottom of the substrate and have a collar portion on the periphery thereof. On the collar portion, leads to be used for connection with other wiring substrate are formed by patterning on copper foil layers.

Abstract: A flexible circuit board including a flexible substrate having an insulating polyimide sheet and a wiring pattern portion formed in a mounting portion and a wiring pattern portion formed in a connecting portion, and a metal substrate on which only the mounting portion of the flexible substrate is secured by means of a thermoplastic polyimide film. Electronic devices are mounted on the mounting portion of the flexible substrate and heat generated by the electric devices can be effectively dissipated through the metal substrate. The connecting portion of the flexible substrate can be connected to an external circuit by means of a connector provided at an edge of the connecting portion. Since the connecting portion is not secured to the metal substrate, connector pins having a large mechanical strength can be used and the connecting portion can be bent at will.

Abstract: A multi-layered electrostrictive effect element comprises films or thin plates of an electrostrictive material and inner electrodes alternatively arranged in layers, the inner electrodes being formed on the entire surface of the films or thin plates of the electrostrictive material, wherein the insulating layer which insulates the inner electrodes exposed on the side end faces of the element comprises a polyimide resin having repeating units represented by the following general formula (I): ##STR1## (wherein X represents a tetravalent group selected from the group consisting of tetravalent phenyl groups; tetravalent biphenyl groups; and tetravalent polyphenyl groups in which at least one of either the phenyl or bipheny groups are bonded through at least one member selected from the group consisting of O, CO, S, CH.sub.2, C(CH.sub.3).sub.2 and C(CF.sub.3).sub.

Abstract: A polyimide film formed by using a symmetrical aromatic meta-substituted primary diamine and a symmetrical aromatic para-substituted primary diamine as raw materials in a specific proportion has excellent heat resistance, electrical properties, flexibility and the like. Such a polyimide film can be bonded to a metal foil not by using any adhesive, but by coating the metal foil with a polyamic acid constituting a precursor of the polyimide and further reacting the polyamic acid to convert it to the polyimide. In this manner, there can be obtained a flexible laminate for printed-circuit board comprising a polyimide film bonded to a metal foil with good adhesion and exhibiting excellent properties as described above.

Abstract: An optical recording method which comprises providing a recording layer containing a recording susbstance that has an absorption maximum in the visible and near infrared wavelength region of 600 to 1,200 nm and loses or diminishes its power to absorb visible or near infrared radiation in the aforesaid wavelength region upon exposure to ultraviolet radiation, X-rays, an electron beam or an ion beam, and irradiating desired locations of the recording layer with ultraviolet radiation, X-rays, an electron beam or ion beam to form a pattern based on the presence or absence, or variation in strength, of the power to absorb visible or near infrared radiation in the aforesaid wavelength region so as to record information in the recording layer; a method for reading optically recorded information which comprises illuminating a pattern formed as described above with laser light having a wavelength in the aforesaid visible and near infrared region and detecting the presence or absence, or variation in intensity, of abso