Abstract: A multilayer circuit board includes a resin body, signal wires, ground conductors, and a via conductor. The resin body includes resin layers made from thermoplastic resin. The signal wires and the ground conductors are each on or inside the resin body. The via conductor connects corresponding ones of the signal wires to each other or corresponding ones of the ground conductors to each other. The ground conductors include a counter ground conductor on or inside the resin body, facing a signal wire in a stacking direction in which the resin layers are stacked, and overlapping the signal wire in plan view in the stacking direction. The counter ground conductor is made of a graphite sheet including main surfaces and end surfaces covered with a conductor layer. The graphite sheet extends over rigid and flexible portions in plan view in the stacking direction.

Abstract: A multilayer circuit board includes a board body including insulator layers stacked upon each other, a first land pattern at the board body to mount a passive component, a second land pattern at the board body to mount an active component, and a heat-dissipation layer between the insulator layers and extending along main surfaces of the insulator layers. The heat-dissipation layer includes a hole extending therethrough in a stacking direction of the insulator layers. In a plan view from the stacking direction, an outer edge of the hole of the heat-dissipation layer is on an outer side of the first land pattern, or overlaps the first land pattern.