PURPOSE: To improve dimensional stability, heat resistance, etc., by continuously pressing and manufacturing a thermosetting resin doped base material wherein a very thin base material of continuous length is doped with thermosetting resin composition, and a copper foil having a surface which is subjected to surface treatment for bonding and has a specified degree of unevenness.

CONSTITUTION: The surface treatment side of a copper foil 12 is piled on a resin doped material 11 of continuous length whose thickness is about 10-50μm. The unevenness of bonding surface treatment of said copper foil is 3.5μm or less. Via an input side vacuum roll 20, the above base material 11 is introduced into a reduced pressure chamber 2 which has discharging vents 24 of cleaned air at an input part and an output part. In this chamber, the base material 11 is heated by far infrared ray heater 23, subjected to fusion bonding by a heating roll 22 under reduced pressure state by a vacuum pump 6, then sent out through an output side vacuum roll 21, introduced between steal belts 33 of a double belt press 3, heated and pressed by the heating part 31 of a pressurizing apparatus 31. Thus the base material is half-cured or cured completely, sent out from the double belt press 3 through a cooling part of a pressurizing apparatus, and cut by a cutter 4.