Patent ID: 8659900

Claim:
A circuit board comprising: a plurality of arms; and a heat radiation plate, wherein each of the arms includes an insulating substrate, wherein, in the each of the arms, a first conductor layer is provided on one of two surfaces of the insulating substrate, and a second conductor layer is provided on the other of the two surfaces of the insulating substrate, wherein, in the each of the arms, an element group including an active element and a passive element are connected to the first conductor layer by a first solder portion, wherein, in the each of the arms, the second conductor layer is connected to the heat radiation plate by a second solder portion, wherein the insulating substrate of the each of the arms includes: a passive element region to which the passive element is connected by the first solder portion; an active element region to which the active element is connected by the first solder portion; and a wiring region on which wiring lines of the element group are laid, and wherein, in the each of the arms, the passive element region, the active element region and the wiring region align in a lengthwise direction of said two surfaces of the insulating substrate, and the passive element region and the wiring region are arranged on both sides of the active element region which is located centrally, and wherein the active element is positioned on the insulating substrate such that a center of gravity of the active element is located at a center of said two surfaces of the insulating substrate.