Nippon Telegraph and Telephone Public Corporation

Nippon Bell Parts Co., Ltd.

Nihon Telecommunication Engineering Corporation

Kiyoshi Murakawa

Toshio Takahashi

Kishio Arita

Copper-nickel-tin alloys having high tensile strength and conductivity suitable for lead conductor materials for integrated circuits are produced by melting a starting material containing 0.5-3.0% by weight of Ni, 0.3-0.9% by weight of Sn, 0.01-0.2% by weight of phosphorus and 0-0.35% by weight of at least one of Mn and Si other than Cu, casting the molten metal, rolling conventionally the cast into a sheet having a thickness corresponding to more than 60% of cold reduction rate of the final necessary gauge, annealing such a rolled sheet at a temperature of 300-395.degree. C. for 1 hour, cold rolling the annealed sheet and annealing the cold rolled sheet at a temperature of 150-250.degree. C. for 1 hour.

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Tokyo, Japan

Kiyoshi Murakawa