Abstract: A high-strength and high-conductivity copper alloy is disclosed which contains essentially of: (a) from 0.5 to 2.5 wt % of Ni; (b) from 0.5 to 2.5 wt % of Co; (c) from 0.5 to 0.8 wt % of Si; (d) from 0.05 to 0.15 wt % of either Mg or P or both; and (e) the balance of Cu. The amounts of Co, Ni, and Si satisfy the following equations: 2%≦(Ni+Co)≦4%, and 0.8≦(Ni/4+Co/6)/Si≦1.2. The new copper alloy exhibits substantially improved electrical conductivity, greater than 65% IACA, than the commercially available C7025 copper alloy, while maintaining a satisfactory tensile strength (greater than 600 MPa), and, thus, can be most advantageously used for preparing leadframes for use in high pin-number (greater than 100 pins) IC application.

Abstract: A high-strength and high-conductivity copper alloy is disclosed which contains essentially of: (a) from 0.5 to 2.5 wt % of Ni; (b) from 0.5 to 2.5 wt % of Co; (c) from 0.5 to 0.8 wt % of Si; (d) from 0.05 to 0.15 wt % of either Mg or P or both; and (e) the balance of Cu. The amounts of Co, Ni, and Si satisfy the following equations: 2%<(Ni+Co)<4%, and 0.8<(Ni/4+Co/6)/Si<1.2. The new copper alloy exhibits substantially improved electrical conductivity, greater than 65% IACA, than the commercially available C7025 copper alloy, while maintaining a satisfactory tensile strength (greater than 600 MPa), and, thus, can be most advantageously used for preparing leadframes for use in high pin-number (greater than 100 pins) IC application.