The development of new copper ball bonding-wire

By adding dopants to high-purity 6N Cu, a new Cu ball-bonding wire, MCl, was developed. This wire offers a number of significant advantages over 6N Cu bonding wire: (1) it is possible to reduce the loop bend and the scattering of loop height when MCl is used instead of 6N Cu wire; (2) although MCl contains some dopants, the ball hardness of MCl is slightly lower than that of 6N Cu wire; (3) MCl has higher ball-bonding strength and wider preferred bonding condition window. It is shown that the ball-neck strength of Cu is stronger than that of Au. This higher strength of Cu ball neck contributes to the excellent loop stability in the molding process. It is also possible to make a long loop, which is essential for high-lead-count semiconductor devices, with this wire.<>