Semiconductor device

A semiconductor device comprising:

• a heat sink;
• a heat dissipation plate disposed above the heat sink;
• a semiconductor element disposed above the heat dissipation plate;
• and
• a case enclosing the semiconductor element and attached to the heat sink,
• wherein the heat dissipation plate has
• a body being flat shaped, and
• a bulge bulging out from a lower end of the body in a form of an arc in cross-sectional view,
• wherein the case has
• an attachment portion extending outward from an outer periphery portion at a lower end portion of the case,
• two attachment holes disposed in positions opposite to each other in the attachment portion, and provided for attachment to the heat sink, and
• two projections individually projecting downward from a lower surface of the attachment portion in positions more adjacent to an outer periphery side of the attachment portion than the two attachment holes, and
• wherein the following expression is satisfied by an angle A formed by an imaginary line connecting the two attachment holes together and an imaginary line connecting together a lowest point of one of the two projections positioned in a surrounding portion of one of the two attachment holes and a contact point between the bulge and the heat sink, with a screw fastened to the heat sink through the one attachment hole, where M represents a vertical distance between the lower end of the body and the lower end of the case, where W represents a bulge amount of the bulge, where T represents a height of the projection, where L represents a horizontal distance from an outer peripheral end of the case to an outer peripheral end of the heat dissipation plate:
• 0<A<arctan((M+W−T)/L).