| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface mounting structure of a semiconductor device, which can prevent the occurrence of solder failure. SOLUTION: In the surface mounting structure 10 provided with a conductive case 2 having a semiconductor element 1 connected thereto and an external lead 3 led out from the case, the external side surface of the case and the connection surface of the external lead are surface-mounted. The external lead has: a bent portion for obtaining a connection surface having the same height as that of external side surface of the case, and a chamfering portion in which the thickness dimension decreases toward an end in the distal end of the bent portion, and also has a curved portion from the external side surface of the case to the bottom surface. In the external lead, the relation between a first tensile stress caused by a first solder fillet formed on the curved portion and a second tensile stress caused by a second solder fillet formed on the chamfering portion satisfies the relation of "first tensile stress * first distance < second tensile stress * second distance", wherein: the boundary between the curved portion and the external side surface of the case is a fulcrum; the first distance is a vertical distance from the fulcrum to the bottom surface of the case; and the second distance is a distance from the fulcrum to the end of the distal end of the external lead. COPYRIGHT: (C)2009,JPO&INPIT
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