To obtain a copper alloy excellent in solderability and free from the generation of plating peeling and blistering by holding the CO concn. in gas in contact with it to a specified volume ratio in a heat treating furnace for a copper alloy rolled strip contg. one or ≥ two kinds of alloy components selected from the group of Ti, Be, Zr, Si, Al, Mg and Cr by a specified weight ratio in total.

A copper alloy rolled strip contains alloy components by 0.01 to 10.0 wt.% in total, and the CO concn. in gas with which the copper alloy rolled strip is brought into contact in a heat treating furnace is held to ≥1.0 vol.%. Preferably, this is a producing method in which the copper alloy moreover contains one or ≥ two kinds of alloy components selected from the group of Ni, Zn, Sn, Fe and P by 0.01 to 10.0 wt.% in total, furthermore, heat treatment is composed of at least one kind among process annealing, solution heat treatment, aging, stress relieving annealing and final annealing, and, moreover, the gas in the furnace is prepd. by burning gaseous hydrocarbon. B right annealing for the copper alloy contg. active metal can be realized without using ammonia cracked gas.