Copper-alloy plate for terminal/connector material, and method for producing copper-alloy plate for terminal/connector material

A copper alloy sheet for terminal and connector materials comprising:

• 4.5 mass % to 12.0 mass % of Zn;
• 0.40 mass % to 0.9 mass % of Sn;
• 0.01 mass % to 0.08 mass % of P;
• and
• 0.20 mass % to 0.85 mass % of Ni,
• with a remainder being Cu and inevitable impurities,
• wherein a content of Zn [Zn] (mass %), a content of Sn [Sn] (mass %), a content of P [P] (mass %) and a content of Ni [Ni] (mass %) have a relationship of 11≦[Zn]+7.5×[Sn]+16×[P]+3.5×[Ni]≦19, and the copper alloy sheet is a copper alloy sheet for terminal and connector materials which further has a relationship of 7≦[Ni]/[P]≦40 with regard to a content of Ni and a content of P in a case in which the content of Ni is in a range of 0.35 mass % to 0.85 mass %,
• an average crystal grain diameter is in a range of 2.0 μm to 8.0 μm,
• an average particle diameter of circular or elliptical precipitates is in a range of 4.0 nm to 25.0 nm or a proportion of the number of precipitates having a particle diameter in a range of 4.0 nm to 25.0 nm in the precipitates is 70% or more,
• an electric conductivity is 29% IACS or more,
• a percentage of stress relaxation is 30% or less at 150° C. for 1000 hours as stress relaxation resistance,
• bending workability is R/t≦0.5 at W bending,
• solderability is excellent, and
• a Young's modulus is 100×103N/mm2 or more.