| 摘要 |
PURPOSE:To increase productive yield, by tin-plating an IC jointing finger only, after gold-plating the whole surface of an overall pattern of a circuit substrate. CONSTITUTION:An Au layer 5 is plated on the pattern surface formed by a copper foil 4 on a circuit substrate 1. An Sn layer 6 is plated thereon. While an Au bump 7 is formed on each jointing electrode of an IC3, a finger 4a is pressurized by heat with it. The Sn layer 6 of the finger 4a is diffused in the Au bump 7 of the IC3. This results in the formation of Au-Sn eutectic alloy and the strong bonding. As the Au layer is formed on the surface of a jointing electrofe 4b for the circuit substrate 1, the jointing conditions among indicating elements can be kept better. |
