A conductive plate includes a first slit formed in the space between a first chip area and a second chip area, a second slit formed in the space between the first chip area and a terminal area, and a third slit formed in the space between the second chip area and the terminal area. The first slit is a continuous line that penetrates through the conductive plate, whereas the second and third slits are continuous lines that do not penetrate through the conductive plate.

A semiconductor device includes first and second conductive parts, a first bonding wire connecting the first and second conductive parts and having a non-flat portion between opposite ends thereof so that a portion between the opposite ends is away from the first and second conductive parts, a case having a housing space to accommodate the first and second conductive parts, including a sidewall having first to fourth lateral faces surrounding the housing space to form a rectangular shape in a plan view, and a cover disposed on the sidewall, a sealing member filling the case to seal the first bonding wire, and a first stress relaxer for relieving a stress in the first bonding wire. The first bonding wire extends from the second lateral face toward the fourth lateral face, and the first stress relaxer is positioned between the first bonding wire and the first lateral face.

A semiconductor device includes first and second conductive parts, a first bonding wire connecting the first and second conductive parts and having a non-flat portion between opposite ends thereof so that a portion between the opposite ends is away from the first and second conductive parts, a case having a housing space to accommodate the first and second conductive parts, including a sidewall having first to fourth lateral faces surrounding the housing space to form a rectangular shape in a plan view, and a cover disposed on the sidewall, a sealing member filling the case to seal the first bonding wire, and a first stress relaxer for relieving a stress in the first bonding wire. The first bonding wire extends from the second lateral face toward the fourth lateral face, and the first stress relaxer is positioned between the first bonding wire and the first lateral face.

When a semiconductor unit is heated, a heater having a flat heating surface is used for performing heating in a state in which a lower surface of an insulated circuit board is placed on the heating surface. When the semiconductor unit is cooled, a cooler having a cooling surface including a pair of support portions is used for performing cooling in which a lower surface of a pair of outer regions of the insulated circuit board are respectively placed to be contact with the pair of support portions, and in which a central region between the pair of outer regions of the insulated circuit board is pressed downward so as to be downward convex.