Sumitomo Bakelite Company Limited

Mamoru Komatsu

Takashi Yamaji

A prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The prepreg comprises an inner layer made from a glass fiber substrate, having a weight of 40 g or more and less than 115 g per square meter and an air permeability or 20 cm /cm /sec or less, impregnated with an epoxy resin, and an outer layer of an epoxy resin coating provided on at least one side of the inner layer, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

Prepreg and process for manufacturing same

A process for manufacturing a prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The process of manufacturing the prepreg comprises (a) a step of impregnating a glass fiber substrate with a solvent, (b) a step of impregnating the solvent-impregnated glass fiber substrate with epoxy resin, (c) a step of heating the epoxy resin-impregnated glass fiber substrate, (d) a step of further impregnating the epoxy resin-impregnated glass fiber substrate, in which the epoxy resin has been cured, with the epoxy resin, and (e) a step of heating the lastly obtained epoxy resin-impregnated glass fiber substrate, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

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Tokyo, Japan

Mamoru Komatsu