| 摘要 |
PURPOSE:To reduce the quantity of metal to be covered on the unnecessary sections on the lead frame by a method wherein all the metal film, excluding a tab, is formed thinner than the film of the tab section when the metal film is formed on the lead frame having the tab by means of a plating method. CONSTITUTION:The lead frame 1, haing three lead wires 3, tab 2 located at the point of the lead wire 3 and wire bonding section 11, is provided. This frame is soaked in the first deep plating tank 15 in such manner that the outer frame 4 is facing upward and the first thin film is formed. Then, the lead frame 1 is soaked in the second shallow plating tank in such manner that the tab 2 and a wire bonding section 11 alone will be immersed in the solution and the second silver-plated film 15 is partially formed. The desirable thickness of the silver-plated film is 2mum or more. Through these procedures, a thick metal layer is formed on the necessary section only and the quantity of the metal used can be reduced. |
