SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide a semiconductor device wherein it is possible to position a semiconductor device mounting an element chip at a high precision and obtain a high heat radiation effect even with the device mounted on a substrate. SOLUTION: A lead frame 2 mounting a semiconductor element chip 6 has a mounting land 4 a plurality parts 4a-4c of which are exposed from a window frame 9 and will be recognized when mounting, this enabling the positioning utilizing the mounting lands made of a metal, etc., having a higher machining accuracy than ceramics and hence the plane positioning to be executed at a high precision in mounting a semiconductor device. The back side of the mounting land 4 is exposed through a window 1a of a base frame 1 and hence the exposed back side of the land 4 is recognized to enable the positioning in the height direction of the semiconductor device to be made at a high precision. From the exposed back side of the land 4, the heat generated by a semiconductor chip 6 is radiated to raise the radiation effect.