Cu-Mg-P-BASED COPPER ALLOY SHEET HAVING EXCELLENT FATIGUE RESISTANCE CHARACTERISTIC AND METHOD OF PRODUCING THE SAME

A Cu—Mg—P-based copper alloy sheet having excellent fatigue resistance characteristics which has a composition containing:

• 0.2% by mass to 1.2% by mass of Mg;
• and
• 0.001% by mass to 0.2% by mass of P, the balance being Cu and unavoidable impurities,
• wherein when X-ray diffraction intensity of a {110} crystal plane is set as I{110}, and X-ray diffraction intensity of a {110} crystal plane of a pure copper standard powder is set as I0{110}, a surface crystal orientation of the copper alloy sheet satisfies a relation of 4.0≦I{110}/I0{110}≦6.0,
• when X-ray diffraction intensity of a {100} crystal plane is set as I{100}, and X-ray diffraction intensity of a {100} crystal plane of the pure copper standard powder is set as I0{100}, the surface crystal orientation of the copper alloy sheet satisfies a relation of I{100}/I0{100}≦0.8,
• when X-ray diffraction intensity of a {111} crystal plane is set as I{111}, and X-ray diffraction intensity of a {111} crystal plane of the pure copper standard powder is set as I0{111}, the surface crystal orientation of the copper alloy sheet satisfies a relation of I{111}/I0{111}≦0.8, and
• an average grain size of the copper alloy sheet is 1.0 μm to 10.0 μm.