Abstract: Providing a copper alloy plate, in which center Mg concentration at a center part in a plate thickness direction 0.1 mass % or more and less than 0.3 mass %, center P concentration is 0.001 mass % or more and 0.2 mass % or less, and the balance is composed of Cu and inevitable impurities; in which surface Mg concentration at a surface is 70% or less of the center Mg concentration; in which a surface layer part defined by a prescribed thickness from the surface has a concentration gradient of Mg of 0.05 mass %/?m or more and 5 mass %/?m or less increasing from surface toward center part of the plate thickness direction; and in which restraint of color change of the surface and increase of electrical contact resistance, and adhesiveness of a plating film are excellent due to maximum Mg concentration in the surface layer part is 90% of the center Mg concentration.

Abstract: This copper alloy for electronic or electric devices includes: Mg: 0.15 mass % or greater and less than 0.35 mass %; and P: 0.0005 mass % or greater and less than 0.01 mass %, with a remainder being Cu and unavoidable impurities, wherein an amount of Mg [Mg] and an amount of P [P] in terms of mass ratio satisfy [Mg]+20×[P]<0.5, and 0.20<(NFJ2/(1?NFJ3))0.5?0.45 is satisfied in a case where a proportion of J3, in which all three grain boundaries constituting a grain boundary triple junction are special grain boundaries, to total grain boundary triple junctions is represented by NFJ3, and a proportion of J2, in which two grain boundaries constituting a grain boundary triple junction are special grain boundaries and one grain boundary is a random grain boundary, to the total grain boundary triple junctions is represented by NFJ2.

Abstract: Providing a copper alloy plate, in which center Mg concentration at a center part in a plate thickness direction 0.1 mass % or more and less than 0.3 mass %, center P concentration is 0.001 mass % or more and 0.2 mass % or less, and the balance is composed of Cu and inevitable impurities; in which surface Mg concentration at a surface is 70% or less of the center Mg concentration; in which a surface layer part defined by a prescribed thickness from the surface has a concentration gradient of Mg of 0.05 mass %/m or more and 5 mass %/m or less increasing from surface toward center part of the plate thickness direction; and in which restraint of color change of the surface and increase of electrical contact resistance, and adhesiveness of a plating film are excellent due to maximum Mg concentration in the surface layer part is 90% of the center Mg concentration.

Abstract: This copper alloy for electronic or electric devices includes: Mg: 0.15 mass % or greater and less than 0.35 mass %; and P: 0.0005 mass % or greater and less than 0.01 mass %, with a remainder being Cu and unavoidable impurities, wherein an amount of Mg [Mg] and an amount of P [P] in terms of mass ratio satisfy [Mg]+20×[P]<0.5, and 0.20<(NFJ2/(1?NFJ3))0.5?0.45 is satisfied in a case where a proportion of J3, in which all three grain boundaries constituting a grain boundary triple junction are special grain boundaries, to total grain boundary triple junctions is represented by NFJ3, and a proportion of J2, in which two grain boundaries constituting a grain boundary triple junction are special grain boundaries and one grain boundary is a random grain boundary, to the total grain boundary triple junctions is represented by NFJ2.

Abstract: A copper alloy includes, by mass %: Mg: 0.15%-0.35%; and P: 0.0005%-0.01%, with a remainder being Cu and unavoidable impurities, wherein [Mg]+20×[P]<0.5 is satisfied. Among the unavoidable impurities, H is 10 mass ppm or less, O is 100 mass ppm or less, S is 50 mass ppm or less, and C is 10 mass ppm or less. In addition, 0.20<(NFJ2/(1?NFJ3))0.5?0.45 is satisfied where a proportion of J3, in which all three grain boundaries constituting a grain boundary triple junction are special grain boundaries, to a total grain boundary triple junctions is NFJ3, and a proportion of J2, in which two grain boundaries constituting a grain boundary triple junction are special grain boundaries and one grain boundary is a random grain boundary, to the total grain boundary triple junctions is NFJ2.

Abstract: A copper alloy includes, by mass %: Mg: 0.15%-0.35%; and P: 0.0005%-0.01%, with a remainder being Cu and unavoidable impurities, wherein [Mg]+20×[P]<0.5 is satisfied. Among the unavoidable impurities, H is 10 mass ppm or less, O is 100 mass ppm or less, S is 50 mass ppm or less, and C is 10 mass ppm or less. In addition, 0.20<(NFJ2/(1?NFJ3))0.5?0.45 is satisfied where a proportion of J3, in which all three grain boundaries constituting a grain boundary triple junction are special grain boundaries, to a total grain boundary triple junctions is NFJ3, and a proportion of J2, in which two grain boundaries constituting a grain boundary triple junction are special grain boundaries and one grain boundary is a random grain boundary, to the total grain boundary triple junctions is NFJ2.