Sumitomo Bakelite Company Limited

Takahiro Nakayama

Tsutomu Watanabe

Sigenori Yamaoka

A metal-clad laminate as a base board for a flexible printed circuit, consisting of a metal foil and a base sheet composed of a fibrous base material impregnated with a resin composition comprising a polyepoxy compound and a styrene copolymer containing structural units of maleic anhydride and/or a monoalkyl maleate. The said resin composition cures rapidly, so that the fibrous base material impregnated with said composition can be laminated in a continuous way with a metal foil and, moreover, the composition imparts to the resulting laminate flexibility and heat resistance suitable for flexible printed circuits. Said resin composition may comprise, in addition to the above-said components, a reactive epoxy diluent, an acrylonitrile-butadiene copolymer, and/or a mixture of a saturated polyester resin and a polyisocyanate compound, in order to improve the flexiblity and adhesion of the base sheet to metal foil. A prepreg obtained by impregnating the fibrous base material with the above-resin composition is not only suitable for manufacturing a flexible printed circuit base board excellent in soldering heat-resistance, bending resistance, and parts-loadability, but also usable as a heat-resistant cover-lay for flexible printed circuits or as an interlayer adhesive sheet.

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Yokohama, Japan

Takahiro Nakayama