Copper alloy strip having high heat resistance and thermal dissipation properties

A copper alloy strip for electrical and electronic parts consisting of:

• 0.20-0.40% by mass of chrome (Cr), 0.01-0.15% by mass of cobalt (Co), and the balance of copper (Cu) and inevitable impurities, and optionally 0.00-0.15% by mass, in total, of at least one selected from the additive element group consisting of silicon (Si), magnesium (Mg) and tin (Sn),
• wherein the copper alloy strip has a softening resistant temperature of 450° C. or higher and thermal conductivity of 280 W/m·K or more,
• wherein an R/t ratio of the copper alloy strip at which no cracks occur during bending at an angle of 90° is 1.0 or less;
• wherein the copper alloy strip is prepared by the following steps, comprising:
• melting elements based on the composition of the copper alloy strip in a melting furnace to cast an ingot;
• homogenization heat treating the acquired ingot at a temperature of 850-1,000° C. for 1-4 hours;
• hot rolling the obtained product from the previous step at a working ratio of 40-95%;
• water quenching the obtained product from the previous step simultaneously with completion of the hot rolling to solution treat at a material surface treatment of 600° C. or higher;
• cold rolling the obtained product from the previous step at a working ratio of 87-98%;
• precipitation heat treating the obtained product from the previous step at a temperature of 430-520° C. for 1-10 hours;
• and
• final cold rolling the obtained product from the previous step at a working ratio of 10-70% to produce a finished product of the copper alloy strip,
• wherein an R/t ratio of the finished product of the copper alloy strip at which no cracks occur during bending at an angle of 90° is 1.0 or less.