Copper alloy for electrical/electronic device and method for producing the same

Abstract

A copper alloy for an electrical and electronic device in accordance with the present invention is characterized in that the copper alloy for an electrical and electronic device includes: nickel (Ni) between 1.5 mass % and 5.0 mass %; silicon (Si) between 0.4 mass % and 1.5 mass %; and a remaining portion formed of Cu and an unavoidable impurity, wherein a mass ratio between Nickel (Ni) and Silicon (Si) as Ni/Si is not smaller than two and not larger than seven, an average crystalline grain diameter is not smaller than 2 μm and not larger than 20 μm, and a standard deviation of the crystalline grain diameter is not larger than 10 μm.

1 . A copper alloy for an electrical and electronic device, comprising:
 Ni between 1.5 mass % and 5.0 mass %;   Si between 0.4 mass % and 1.5 mass %; and   a remaining portion formed of Cu and an unavoidable impurity,   wherein said copper alloy has a mass ratio of Ni/Si not smaller than two and not larger than seven, an average crystalline grain diameter not smaller than 2 μm and not larger than 20 μm, and a standard deviation of a crystalline grain diameter not larger than 10 μm.   
   
   
       2 . The copper alloy for the electrical and electronic device according to  claim 1 , wherein said average crystalline grain diameter is within a range not larger than 15 μm, and said standard deviation of the crystalline grain diameter is not larger than 8 μm. 
   
   
       3 . The copper alloy for the electrical and electronic device according to  claim 1 , wherein said average crystalline grain diameter is within a range not larger than 10 μm, and said standard deviation of the crystalline grain diameter is not larger than 5 μm. 
   
   
       4 . The copper alloy for the electrical and electronic device according to  claim 1 , further comprising at least between 0.005 mass % and 2.0 mass % of one selected from the group consisting of Mg, Sn and Zn, said remaining portion being formed of Cu and the unavoidable impurity. 
   
   
       5 . The copper alloy for the electrical and electronic device according to  claim 1 , further comprising at least between 0.005 mass % and 2.0 mass % of one selected from the group consisting of Ag, Co, Cr, Fe, Mn, P, Ti and Zr, said remaining portion being formed of Cu and the unavoidable impurity. 
   
   
       6 . A method for producing a copper alloy for an electrical and electronic device, comprising at least a step a, a step b, and a step c as follows:
 the step a of casting a copper alloy including Ni between 1.5 mass % and 5.0 mass %; Si between 0.4 mass % and 1.5 mass %; and a remaining portion formed of Cu and an unavoidable impurity, said copper alloy having a mass ratio of Ni/Si not smaller than two and not larger than seven, and performing hot working and cold working;   the step b of performing a re-crystallization heat treatment with a temperature rising rate of not slower than 10° C. per second, at an end point temperature between 700° C. and 950° C., for a retention time between five seconds and 300 seconds, and with a cooling rate not slower than 20° C. per second till 300° C. after the step a; and   the step b of performing an aging precipitation after the step b.