Patent ID: 7439614

Claim:
A circuit device comprising: a board for mounting a circuit element, wherein the board comprises a plurality of wiring layers which are laminated to have multiple layers with an insulation layer interposed therebetween, wherein at least two wiring layers comprise a conductive pattern which is electrically connected to a built-in circuit element and which configures a part of an electric circuit, and a dummy pattern which is electrically independent of the electric circuit, wherein dummy patterns formed on the respective wiring layers are thermally connected to one another with a connection part which penetrates the insulation layer, and wherein the connection part comprises a first connection part which extends upward in a convex shape from the wiring layer located below the insulation layer and a second connection part which extends downward in a convex shape from a wiring layer located above the insulation layer, and the first connection part and the second connection part make contact in the middle of the insulation layer in the thickness-wise direction.