MANUFACTURE OF PRINTED WIRING BOARD

PURPOSE:To enable a pre-treatment of high reliability to be carried out by a method wherein a through-hole is bored in a multilayered board at a required point, the multilayered board is dipped into an electrolytic solution, and a certain potential is applied between the terminal of the multilayered board which is made to serve as an electrode and an external electrode, then a conductor layer is formed on the inner wall of the through-hole and the outer layer of the multilayered board through chemical plating or electroplating, and an outer circuit pattern is provided. CONSTITUTION:An inner base 2 provided with an inner circuit pattern l and a terminal 3 connected to the circuit pattern 1 is prepared, and a multilayered board 6 is formed interposing a prepreg. Then, a through-hole 7 is bored in the board 6 at a required point, the board 6 is dipped into an electrolytic solution, a terminal 3 protruding from the end of the board 6 is made to serve as an electrode, a power supply is applied between the terminal 3 and an external electrode, a current is made to flow between the terminal 3 and the external electrode, and smears and cuttings attached to the joint of the inner layer of the through-hole 7 are made to suspend in the electrolytic solution together with copper. Then, a plating 8 is deposited through chemical plating or electroplating, an outer circuit pattern 9 is formed, and the end of the board 6 is cut off at a cut surface 10, whereby a printed wiring board 11 can be obtained.