| 摘要 |
PURPOSE:To make the yield rate of the material for lead frames to be the maximum, in the lead frames, in each of which four leads are extended radially from the central part and one lead of them is longer than the others, and which are used for transistors, by arranging each lead at a specified angle. CONSTITUTION:Four leads are radially extended from the central part at an equal angle of 90 deg. for every transistor. The length B of one lead 2b among them is longer than the length A of the other three leads 2a. Such a lead frame is used for the transistor. The lead frames 3 are connected and aligned along the long line of a plurality of transistors. The leads are arranged so that an angle theta, which is formed by the long lead 2b and the longitudinal direction of the frame (shown by arrows 6), becomes tan<-1>B/A. In general, a ratio between the lengths A and B of the leads of the transistor in such a type is about 3:5. Therefore, the lead frame having the best yield rate is obtained when theta is made to be tan<-1>B/A. |
