Method for producing a copper alloy sheet and a copper alloy plate

Stress corrosion cracking resistance, stress relaxation characteristics, tensile strength, proof stress, electrical conductivity, bending workability, and provides a copper alloy sheet excellent in solderability. The copper alloy sheet, and 4 to 14 wt% of Zn, and 0.1 to 1 wt% Sn, and P of 0.005 to 0.08 mass%, 1.0 to 2.4 wt% of Ni containing bets, the balance being Cu and unavoidable impurities, 7 ≦ [Zn] + 3 × [Sn] + 2 × [Ni] ≦ 18,0 ≦ [Zn] -0.3 × [Sn] -1.8 × [Ni] ≦ 11,0.3 ≦ (3 × [Ni] + 0.5 × [Sn]) / [Zn] ≦ 1.6,1.8 ≦ [Ni] / [Sn] ≦ 10,16 ≦ has a relation of [Ni] / [P] ≦ 250, the average crystal grain size 2～9Myuemu, average particle diameter of the circular or precipitates elliptical particle diameter of 3~75nm or the deposit ratio of the number of precipitates 3~75nm occupied 70% or more, conductivity of 24% IACS or more, 0.99 ° C. as stress relaxation property, 1000 hours the stress relaxation ratio at 25% or less That.