Copper alloy material and method of making same

1. A method of making copper alloy material, comprising:

preparing a copper alloy raw material comprising:

1.0 to 5.0 mass % of Ni;

0.2 to 1.0 mass % of Si;

1.0 to 5.0 mass % of Zn;

0.1 to 0.5 mass % of Sn;

0.003 to 0.3 mass % of P; and

a balance consisting of Cu and unavoidable impurities;

wherein a mass ratio between Ni and each of Si, Zn and Sn is to be Ni/Si=4 to 6, Zn/Ni=0.5 or more, and Sn/Ni=0.05 to 0.2;

conducting a first cold rolling step, wherein the copper alloy raw material is cold-rolled down to a thickness of 1.3 to 1.7 times thicker than a target thickness of a final product;

conducting a first heat treatment step, wherein the cold-rolled material in the first cold rolling step is heated to 700 to 900° C. and then cooled to 300° C. or less at a cooling rate of 25° C./min or more;

conducting a second cold rolling step, wherein the treated material in the first heat treatment step is cold-rolled down to the target thickness;

conducting a second heat treatment step, wherein the cold-rolled material in the second cold rolling step is heated to 400 to 500° C. and held for 30 min. to 10 hrs.; and

conducting a third heat treatment step, wherein the treated material in the second heat treatment step is heated at 400 to 550° C. for 10 sec. to 3 min. while applying a tension of 10 to 100 N/mm 2 in a longitudinal direction of the treated material.

2. The method of claim 1 , wherein the copper alloy material has a tensile strength of 800 N/mm 2 or more.

3. The method of claim 1 , wherein the copper alloy material has an elongation of 8% or more.

4. The method of claim 1 , wherein the copper alloy material has a conductivity of 35% IACS or more.

5. The method of claim 1 , wherein the mass ratio of Ni/Si is 4.3 to 5.0.

6. The method of claim 1 , wherein the copper alloy material is designed to be used together with a Pb-free solder.

7. The method of claim 1 , wherein the copper alloy material is designed to be bonded by using a Pb-free solder.