摘要 |
Nickel films 22, 25 are formed on copper pads 21, 24 on a substrate 11, and gold layers 23, 26 are further formed on the nickel films 22, 25. To suppress formation of compound of gold and tin which spoils reliability of soldering, formation of gold layers 23, 26 on the nickel films 22, 25 is effected by very thin substitutional plating method. As a result, a solder bump 17 is formed favorably. Besides, an nickel oxide film 32 formed on the surface of the gold layer 23 is removed by plasma etching. As a result, bonding of wire 15 is also excellent.
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