Patent ID: 7263769

Claim:
A method of producing a multi-layered flexible print circuit board comprising: a one-sided circuit board forming step of forming a first circuit layer on one side of a first insulating layer and insulating layer on the other side thereof to form a first one-sided circuit board and forming a second circuit layer on one side of a second insulating layer to form a second one-sided circuit board; a through-hole forming step of forming a through-hole for connecting between the first circuit layer and the second circuit layer in the one-sided circuit board in the thickness direction; a metal portion forming step of press-fitting a substantially spherical conductor made of a metallic material at least on the surface thereof into the through-hole to make conduction to the first circuit layer so that a metal portion extending from the surface of the first insulating layer is formed; and a conducting step of laminating the first one-sided circuit board and the second one-sided circuit board on each other and press-deforming the metal portion such that the metal portion and the second circuit layer are electrically-conducted to each other to electrically-conduct the first circuit layer and the second circuit layer to each other via the metal portion; and the insulating layer is an adhesive layer for laminating the first one-sided circuit board and the second one-sided circuit board on each other.