| 摘要 |
PROBLEM TO BE SOLVED: To obtain a prepreg having a high relative dielectric constant, and to obtain a printed circuit board in which the prepreg has been used and which has a good strength and a high density. SOLUTION: This method for producing the prepreg, characterized by coating a thermosetting resin composition containing 10 to 99 wt.% of an insulating powdery inorganic filler having a relative dielectric constant of >=50 at room temperature on one side of each of thermoplastic films, drying the coated resin composition to form the B-stage resin composition layer on each side of the films, disposing the thermoplastic films on both the sides of a fiber fabric substrate so that the resin layers of both the thermoplastic films are directed to the substrate, and then adhering the formed resin layers to both the sides of the fiber fabric substrate. The thermosetting resin composition preferably is a resin composition obtained by homogeneously compounding 10 to 99 wt.% of an insulating inorganic filler having a relative dielectric constant of >=50 at room temperature and a specific surface area of 0.30 to 1.00 m2/g with a resin composition comprising (a) a polyfunctional cyanate compound, (b) an epoxy resin liquid at room temperature, and a thermal curing catalyst. The high relative dielectric constant prepreg is used to produce the high density printed circuit board. Thereby, the prepreg having the high relative dielectric constant can be produced, and the printed circuit board in which the prepreg has been used and which has excellent heat resistance, electric characteristics after the absorption of moisture, excellent adhesivity to copper foils, excellent strength, and so on can be produced.
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