| 摘要 |
PURPOSE:To improve solder wetting of a lead frame and increase its corrosion resistance to molding resin by preparing a lead frame of an alloy layer that includes a first metal nobler than nickel and a second metal having equal or better solder wetting than the lead-frame base, and maintaining the alloy layer at slightly higher potential than the corrosion potential of the lead-frame base. CONSTITUTION:An alloy plating 2 is applied all over a lead frame 1 composed of 42 alloy. A silicon chip 6 is bonded with solder 7 to a die pad 3 on the lead frame. Aluminum electrode pads on the silicon chip and inner leads 4 are partially plated with silver. The aluminum pads and inner leads are interconnected through gold wire by ball bonding at the electrode pads and wedge bonding at the inner leads. Then, the chip is molded with epoxy resin 9. The alloy plating 2, containing molybdenum, serves to prevent oxidation of the lead frame at the interface with the epoxy resin. This improves device reliability in moisture resistance.
|
