Semiconductor device with packaging material and metal member protruding from the packaging material

A semiconductor device manufacturing method comprising:

• a step of mounting a semiconductor element on a lead frame;
• a step of encapsulating the semiconductor element with a packaging material such that the lead frame is partially exposed, the packaging material forming an exterior surface of the semiconductor device, the packaging material having a front surface, a rear surface opposite to the front surface, and an end face connecting the front surface and the rear surface;
• and
• a step of cutting the lead frame in a predetermined pattern to separate the packaging material from the lead frame while leaving the lead frame remaining on the packaging material side as a metal member that has an island portion on which the semiconductor element is mounted, and a protruding portion protruding from the end face of the packaging material and having a front surface and a rear surface that are exposed from the package material, wherein
• a peripheral edge of the protruding portion that appears by cutting the predetermined pattern has a lateral peripheral edge forming an end portion of the protruding portion opposite to the end face of the packaging material such that the lateral peripheral edge is apart from the end face of the packaging material and extends along a direction parallel to the end face of the packaging material, a longitudinal peripheral edge along the normal direction of the end face, and a corner peripheral edge formed by side portions that are disposed at the corners of the protruding portion and continue to the lateral peripheral edge and the longitudinal peripheral edge, wherein
• the corner peripheral edge includes a first side portion intersecting substantially orthogonally with the lateral peripheral edge and extending toward the end face of the packaging material and a second side portion with one end thereof intersecting substantially orthogonally with the first side portion and the other end intersecting substantially orthogonally with the longitudinal peripheral edge, wherein
• an intersecting portion between the first side portion and the second side portion includes a curved shape portion which bulges toward the packaging material and has a center point of curvature facing the packaging material, wherein
• the protruding portion of the metal member includes a heat dissipation fin to dissipate heat generated in the semiconductor device and has a maximum width in a direction parallel to the end face of the packaging material which is approximately the same as a width of the end face of the packaging material, wherein
• most of a surface of the island portion opposite to the semiconductor element is exposed from the rear surface of the packaging material, wherein
• the lateral peripheral edge and the longitudinal peripheral edge are outermost peripheral edges of the semiconductor device, and the corner peripheral edge is formed only at a corner of the outermost peripheral edges, wherein
• the front surface of the protruding portion is extended outwardly from a middle part of the end face of the packaging material in a thickness direction of the packaging material, wherein
• the rear surface of the protruding portion is opposite to the front surface of the protruding portion in the thickness direction of the packaging material such that the rear surface of the protruding portion is on the same level plane with the rear surface of the packaging material, wherein
• the corner peripheral edge has the same plan view from the front surface of the protruding portion to the rear surface of the protruding portion, and wherein
• a length L2 of the second side portion is longer than a length L1 of the first side portion.