Method of manufacturing semiconductor device and semiconductor device

A method of manufacturing a semiconductor device, comprising the steps of:

• (a) preparing a lead frame including a switching element die pad connected to a power side terminal arranged on a side of a first side in plan view, a control element die pad connected to a control side terminal arranged on a side of a second side opposite to the first side, and a third-side side rail portion provided on a side of a third side different from the first side and the second side;
• (b) mounting a switching element and a diode element on the switching element die pad and mounting a control element configured to control the switching element on the control element die pad;
• (c) sealing the switching element, the diode element, and the control element with a mold resin such that the power side terminal, the control side terminal, and a part of the third-side side rail portion protrude outward;
• and
• (d) forming a third-side side rail terminal by cutting the third-side side rail portion, the third-side side rail terminal extending from a part of the third-side side rail portion.