| 摘要 |
PURPOSE:To enhance the flexibility while reducing the cost by performing thermosonic wire bonding, providing a electroless Ni plating film on a conductor and a substituted Au plating film having thickness within a specified range thereby performing satisfactory wire bonding. CONSTITUTION:A plastic film 1, a copper conductor 2, an electroless Ni plating film 3, and a substituted Au plating film 4 of 0.2-0.01mum thick are provided sequentially. Thermosonic wire bonding is employed. When the thickness of the substituted Au plating film 4 is 0.2mum or above, the immersion time of a flexible printed circuit board into Au plating bath is prolonged to cause lowering of mechanical strength and the cost is increased due to increase of required quantity of Au. When the thickness of the substituted Au plating film is 0.01mum or less, defect such as a pinhole appears in the Au plating film 4 and a satisfactory anti-oxidation effect can not be achieved on the surface of the Ni plating film 3. |
