| 摘要 |
PURPOSE: To obtain a prepreg reduced in the flow-out of a resin from a substrate, and useful for multi-layer printed wiring boards free from the generation of burr with the flowed resin, troubles on bending, the shortage of the interlaminar thickness, the failure of charging, etc., by enhancing the hardness of the surface layer(s) on one side or both the sides of the prepreg on comparison with those of other parts. CONSTITUTION: The surface of a prepreg is subjected e.g. to a heating treatment with far IR light to enhance the hardness of the surface layer or surface layers on the surface or both the surfaces of the prepreg in comparison with those of other parts. For example, the resin in the surface layer or surface layers on one side or both the side and the resin in other parts have a gel time difference of 3-80%. The prepreg is obtained by raising the temperature of the surface layer in a short time to enhance the hardness of the surface layer, and subsequently cooling the heated surface layer, before the temperatures of inner parts follow the temperature of the surface layer. Thus, only the surface layer is heated so as not to transmit the heat to the inner parts. |
