| 摘要 |
PURPOSE:To prevent an external lead mainly containing copper of a semiconductor device from being corroded due to the drop of a soldering film formed on the lead at the time of bending the lead by providing a lead-plated film on the surface of the external lead. CONSTITUTION:A lead-plating layer 4 having 2-3mum of thickness is electrolytically plated on an external lead material 1 made copper, is then dippled in a boron fluorinated solder plating bath, and a solder film 2 having 7-8mum of thickness is formed on the lead material. Since the internal stress of the lead plated film is thus small due to reduced thickness, the external lead is merely cracked, even if bent, at the solder plated layer, but the external lead protected by the lead plated layer is not corroded. |
