Patent ID: 7060912

Claim:
A circuit board comprising a board substrate including a substrate layer formed with a pad on an upper surface thereof, and a metal piece soldered on the pad, wherein the pad includes a mounting region held in contact with the metal piece and a non-mounting region held out of contact with the metal piece; and wherein the substrate layer is provided with a plurality of through-holes covered by the mounting region of the pad, the substrate layer being also provided with a plurality of through-holes covered by the non-mounting region of the pad, each through-hole including an internal wall formed with a conductive film, each through-hole being filled with a predetermined filler; and wherein the pad is connected integrally with the conductive film on the internal wall of each through-hole; wherein the board substrate is a multi-layered substrate including the substrate layer as a top layer; and at least one of the through-holes being a deeper through-hole having a depth corresponding to an entire thickness of the multi-layered substrate, the remaining ones of the through-holes being shallower through-holes each having a depth smaller than the entire thickness of the multi-layered substrate, the deeper through-hole being electrically connected to all of the shallower through-holes via said pad.