Cu—Ni—Si based rolled copper alloy and production method thereof

1. A rolled copper alloy, comprising: a total amount of 3.0 to 4.5% by mass of at least one or more selected from the group consisting of Ni and Co, 0.6 to 1.0% by mass of Si, a total amount of 2.5% or less by mass of one or more selected from the group consisting of Mg, Mn, Sn, Zn, and Cr, and the balance Cu and inevitable impurities, wherein a 0.2% yield strength YS in a direction transverse to rolling direction is 1040 MPa or more, and a repeated stress σ in a fatigue test when a repeat count exceeds 10 4 is 750 MPa or more, wherein the fatigue test is carried out under complete reversed plane bending according to JCBA-T308-2002 and a strip sample having a width of 10 mm is taken so that a length direction of the sample is at the direction transverse to rolling direction, and test conditions are set to provide a relationship among a maximum stress σ m applied to a surface of the sample, an amplitude f described in mm and a distance L described in mm between a fulcrum and a stress action point as follows: L=√(3tEf/(2σm)), where t is a sample thickness described in mm and E is a Young's modulus described in MPa measured according to JCBA-T3312-2002, and further wherein an electric conductivity EC (% IACS) in the direction transverse to rolling direction is 26% or more to 39% or less.

2. The rolled copper alloy according to claim 1 , comprising a total amount of 0.005 to 2.5% by mass of one or more selected from the group consisting of Mg, Mn, Sn, Zn and Cr.

3. The rolled copper alloy according to claim 1 , further comprising a total amount of 0.005 to 1.0% by mass of one or more selected from the group consisting of P, B, Ti, Zr, Al, Fe and Ag.

4. The rolled copper alloy according to claim 2 , further comprising a total amount of 0.005 to 1.0% by mass of one or more selected from the group consisting of P, B, Ti, Zr, Al, Fe and Ag.