Method of manufacturing semiconductor device

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

• (a) providing a lead frame including a plurality of product formation regions each having a die pad having an upper surface and a lower surface opposite to the upper surface, a plurality of suspension leads each coupled to the die pad, a plurality of leads arranged around the die pad, and arranged between the suspension leads, and dam portion coupled to the leads;
• (b) mounting a semiconductor chip, having a first main surface, a plurality of electrode pads formed on the first main surface, and a second main surface opposite to the first main surface, on the upper surface of the die pad;
• (c) electrically coupling the electrode pads of the semiconductor chip and the leads via a plurality of conductive members, respectively;
• (d) providing a molding die having an upper die, a first cavity formed in the upper die, a gate portion arranged outside a first corner portion of the four corner portions of the first cavity, and a lower die facing the upper die, a shape in a plan view of the first cavity being a quadrangle;
• (e) disposing the lead frame on which the semiconductor chip is mounted between the upper die and the lower die such that the semiconductor chip is arranged inside of the first cavity, clamping a clamp area located around an area of the lead frame overlapped with the first cavity, and in this state, sealing the semiconductor chip, the conductive members, and an inner lead of each of the leads with resin such that a lower surface of each of the leads is exposed, and forming a sealed body;
• and
• (f) at an inside of the dam portion of each of the product formation regions, cutting the leads and the suspension leads, and separating the product formation regions into individual pieces,
• wherein in the lead frame, a plurality of air vent portions, which discharge gas in the first cavity to outside the first cavity in the step (e), are formed at positions, respectively, overlapping with the other corner portions of the first cavity, and
• wherein the air vent portions are led out from the other corner portions of the first cavity to outside the clamp areas, respectively, and each of the air vent portions is formed by jointing together a plurality of hole portions penetrating the lead frame and a plurality of hole portions jointing together the groove portions.