NOVELTY - A case (304) is configured of two heat dissipating plates (307A, 307B) facing respective surfaces of a sealing structure (302). An intermediate unit of case is provided with a thin portion (304A) surrounding the main heat dissipating plate, and has a thickness thinner than the thickness of the main heat dissipating plate. The thin portion is elastically deformed more easily than the main heat dissipating plate. The sealing structure is pressed against the auxiliary heat dissipating plate and affixed by an elastic force generated in the thin portion with the main heat dissipating plate.    USE - Power module used for power converter device such as inverter of vehicle such as hybrid or electric vehicle.    ADVANTAGE - The productivity and connection reliability can be improved while accommodating a resin-molded semiconductor device in a case. The size and the heat dissipation can be also reduced using the heat dissipating plates, thus reducing the size of the power converter device. The power module can be cooled efficiently so as to improve the reliability of the power module. A frame is made with a thickness larger than the thickness of thin portion so as to improve the strength of the case. The heat balance can be homogenized and the heat resistance can be improved since the electric current can be prevented in a laminated conductor board. The management of wiring in the power converter device can be made easy by making multiple alternating current bus-bars project from one surface of a flow-path formation section so as to increase the productivity. The temperature rise of the sensors can be prevented by transmission of heat to a coolant. The sealing structure can be positioned precisely. The need for manufacturing of a jig tool can be decreased and the reliability of the manufacturing process can be increased.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacturing method of power module.    DESCRIPTION OF DRAWING(S) - The drawings show the perspective view of the sealing structure and sectional diagram of the case.    Sealing structure (302)    Case (304)    Thin portion (304A)    Flange (304B)    Heat dissipating plates (307A, 307B)