Cu—Ni—Si alloy for electronic material

1. A copper alloy for electronic materials comprising 0.4 to 6.0% by mass of Ni and 0.1 to 1.4% by mass of Si, with the balance being Cu and unavoidable impurities, the copper alloy comprising:

small particles of Ni—Si compound having a particle size of equal to or greater than 0.01 μm and smaller than 0.3 μm; and

large particles of Ni—Si compound having a particle size of equal to or greater than 0.3 μm and smaller than 1.5 μm;

wherein the number density of the small particles is 1 to 2000 pieces/μm 2 and the number density of the large particles is 0.05 to 2 pieces/μm 2 .

2. The copper alloy for electronic materials according to claim 1 ,

wherein a maximum value of a density ratio between fields of vision with regard to the small particles is 10 or less if a unit area of 0.5 μm×0.5 μm is set to one field of vision and 10 fields of vision selected from a surface area of the copper alloy of 100 mm 2 are observed, and a maximum value of a density ratio between fields of vision with regard to the large particles is 5 or less if a unit area of 20 μm×20 μm is set to one field of vision and 10 fields of vision selected from a surface area of the copper alloy of 100 mm 2 are observed.

3. The copper alloy for electronic materials according to claim 1 ,

wherein a ratio of the average particle size of the large particles with regard to the average particle size of the small particles is 2 to 50.

4. The copper alloy for electronic materials according to claim 1 ,

wherein an average grain size indicated by a circle-equivalent diameter is 1 to 30 μm if observed from a cross section in a thickness direction parallel to a rolling direction.

5. The copper alloy for electronic materials according to claim 1 , wherein a maximum value of a ratio of particle sizes of neighboring grains is 3 or less in length in the thickness direction parallel to the rolling direction.

6. The copper alloy for electronic materials according to claim 1 , further comprising at least one selected from the group consisting of Cr, Co, Mg, Mn, Fe, Sn, Zn, Al, and P in an amount of 1.0% by mass in total.

7. A wrought copper product made from the copper alloy according to any of claims 1 to 6 .

8. An electronic component prepared with the copper alloy according to any of claims 1 to 6 .

9. A method of producing the copper alloy according to any one of claims 1 to 6 , the method comprising, in order:

melting and casting ingot having a desired composition after maintaining molten metal obtained by melting materials containing Ni and Si at 1130 to 1300° C. if Ni concentration is 0.4 to 3.0% by mass and maintaining molten metal obtained by melting materials containing Ni and Si at 1250 to 1350° C. if Ni concentration is 3.0 to 6.0% by mass;

performing hot rolling after heating at 800 to 900° C. if Ni in the ingot is less than 2.0% by mass, at 850 to 950° C. if Ni in the ingot is equal to or greater than 2.0% by mass and less than 3.0% by mass, at 900 to 1000° C. if Ni in the ingot is equal to or greater than 3.0% by mass and less than 4.0% by mass, and at equal to or higher than 950° C. if Ni in the ingot is equal to or greater than 4.0% by mass;

performing cold rolling;

performing a solution treatment at a solution treatment temperature, y (° C.) indicated by y=125x+(475 to 525) if x is Ni concentration (% by mass) in the ingot; and

performing an aging treatment.