| 摘要 |
PURPOSE:To avoid cracking of a semiconductor device created by a thermal stress at the time of outputting even if a large size semiconductor device is mounted by a method wherein a tab and leads are made of different materials and the difference between the thermal expansion coefficient of the tab and the thermal expansion coefficient of the semiconductor device is made to be small. CONSTITUTION:A lead frame 10 is constituted by a tab 3' which is made of Fe-42% Ni alloy whose thermal expansion coefficient is less the 1.0X10<-5>/deg and leads 4' which are made of Cu-3% Sn alloy whose tensile strength is less than 40kg/mm<2> and elongation at break is more than 10%. After the tab 3' and the leads 4' are formed by stamping independently, they are connected to each other by spot welding. A semiconductor device 2 is mounted on the tab 3' with a junction layer 5 made of silver paste between and the junction layers 5 provided on the tips of the inner lead portions 4a of the leads 4' are connected to the semiconductor device 2 by bonding wires 7. The semiconductor device 2 and the inner lead portions 4a are sealed with sealing plastic 6 and the tips of the outer lead portions 4b of the leads 4' are bent toward the bottom of the sealing plastic 6 and soldered onto a printed wiring board or the like to form a chip carrier. |
