Matsushita Electric Works, Ltd.

Atsuhiro Nakamoto

Toshiyuki Suzuki

Ryuji Otani

Masahiro Matsumura

Yoshihisa Sugawa

Tohru Nobutani

Kunji Nakashima

Takahiro Miyano

Kenzi Ogasawara

Yoshitaka Tezuka

Hideo Izumi

In a method of manufacturing a printed circuit board, a photoresist layer is formed on a three-dimensionally molded substrate through a conductive layer. A planar photomask which is provided with a mask pattern and a light-transmissive pattern is placed in front of the photoresist layer. A parallel light beam is radiated to the photomask in order to give to the photoresist layer an exposed pattern of an intended width 'L' in correspondence to the light-transmissive pattern. In the present invention, the light-transmissive pattern is configured so as to satisfy the following relations:

Method of manufacturing a printed circuit board

A method for forming a conducting metal layer on an inorganic substrate is to heat the inorganic substrate accommodated in a vacuum vessel of sputtering device in which a high degree of vacuum is attained, to lead into the vacuum vessel a discharge gas as regulated to be at a predetermined pressure, to apply a high frequency power with the inorganic substrate made as a target, to interrupt the power to regulate the discharge gas to be at a predetermined pressure relatively low, and to apply DC power with a conductive metal member made as a target for thereby forming the conducting metal layer on the inorganic substrate. The metal layer formation on the inorganic substrate is thereby simplified enough for improving the producibility in industrial scale and is still capable of attaining a satisfactory bonding strength between the metal layer and the substrate.

Method for forming conducting metal layer on inorganic substrate

Superior polyimide prepolymers particularly suitable for fabrication of multi-layer printed boards are produced by reacting unsaturated bisimides with diamines to consist essentially of 41-55% of unreacted reactants, 39-54% of components having a molecular weight of between 400 and 15,000, and 3.0-6.8% of components having a molecular weight of more than 15,000. The resulting prepolymers enable the preparation of their solution having enough working life for successfully impregnating a given substrate therewith in the preparation of prepregs. The prepregs, prepared from the above prepolymers in such a way as to contain within the resin content thereof 29-35% of unreacted reactants, 51-65% of the components having a molecular weight of between 400 and 15,000, and 5-14% of the components having a molecular weight of more than 15,000, allow the fabrication of laminate products with remarkable dimension stability under a low molding pressure to eliminate the presence of voids in the products, in addition to that the prepregs ensure a high bond strength as well as elongated working life which is responsible for prevention of a blister in the finished laminate and for easy control of the laminate forming process.

Polyimide prepolymer composition from unsaturated bisimide and diamine

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Kadoma, Japan

Atsuhiro Nakamoto