Patent ID: 8153905

Claim:
A method for manufacturing a printed wiring board, comprising: preparing an insulative board; forming a metal film on a surface of the insulative board; forming a plating resist on the metal film; forming a plated-metal film on the metal film exposed from the plating resist; covering a portion of the plated-metal film with an etching resist; etching to reduce a thickness of the plated-metal film exposed from the etching resist; removing the etching resist; removing the plating resist; forming a wiring having a pad and a conductive circuit thinner than the pad by removing the metal film exposed through the removing of the plating resist; forming a solder-resist layer on the surface of the insulative board and the wiring; forming in the solder-resist layer an opening that exposes the pad and a portion of the conductive circuit contiguous to the pad; forming a solder film on the pad and the portion of the conductive circuit exposed through the opening; and forming a solder bump on the pad by agglomerating solder on the pad through a reflow, wherein the pad has a pad thickness which is greater than a circuit thickness of the conductive circuit, the solder bump on the pad has a first bump thickness which is greater than a second bump thickness of the solder bump on the conductive circuit, and the pad thickness, the circuit thickness, the first bump thickness, and the second bump thickness are in a direction orthogonally to the surface of the insulative board.