Patent ID: 7750249

Claim:
A method for manufacturing a multilayer printed circuit board on which electrical devices are mounted and a plurality of insulating layers and a plurality of conducting layers alternately are stacked and conducting paths are formed along an approximately vertical direction to the conducting layers, said method comprising: a conducting path forming process of forming said conducting paths on a board on which the plurality of insulating layers and the plurality of conducting layers are alternately stacked and forming a plurality of first conducting paths passing through said board and second conducting paths also passing through said board so as to be surrounded by said plurality of first conducting paths, wherein said conducting path forming process comprises a first process of forming a plurality of cylindrical or pillar-shaped conducting portions at both ends of each main body of which edge conducting portions are formed on said board so that said edge conducting portions being adjacent to one another come near to or come into contact with one another at least within a specified distance, a second process of punching a center portions of regions in which the plurality of conducting portions is placed so that partial portions on center portion sides of said edge conducting portions are removed and so that said edge conducting portions being adjacent to one another are at least separated to form first through-holes so as to form said first conducting paths, a third process of forming, after said first through-holes are filled with an insulator, second through-holes each having a cross-sectional dimension being smaller than that of each of said first through-holes within said first through-holes filled with said insulator, and a fourth process of forming conducting layers in inner walls of said second through-holes so that said second conducting paths are formed.