MULTILAYERED PRINTED-WIRING BOARD AND MANUFACTURE OF MULTILAYERED PRINTED-WIRING BOARD

PROBLEM TO BE SOLVED: To prevent the location which correspond to the through holes formed in internal layer wiring boards on the outer surfaces of films, from bulging up at the time of heating by a method wherein a four-layer printed-wiring board is provided with the internal layer wiring boards, the films, which are respectively made to closely adhere to the outer surfaces of the wiring boards, and conductor layers, which are respectively formed on the outer surfaces of the films. SOLUTION: A four-layer printed-wiring board 1 is constituted of internal layer wiring boards 2, films 3, which are respectively made to closely adhere to both sides of the surfaces and rears of the wiring boards 2, external layer circuits 4, which are respectively formed on the outer surfaces of the films 3, a through hole 5, through which the circuits 4 and 4 on the surface and and rear of the board 1 are connected with each other, and the like. The boards 2 are respectively constituted into a structure, wherein a conductor layer is formed by an additive method, internal layer circuits 6 are respectively formed on both surfaces of the surface and rear of a laminated board 2a and at the same time, a through hole 7, through which the circuits 6 and 6 are connected with each other. The films 3 are respectively pressure bonded to both surfaces of the surfaces and rears of the wiring boards 2 in a state that a synthetic resin layer having insulation properties is softened. The circuits 4 are formed by applying an electroless plating to the films 3 with bonding agents 8 applied on their outer surfaces.