The Improvement of Sweep Stiffness and Thermomechanical Properties of Wire Bonds for Pure Gold Wire with Dopant

The materials used in this study were three types of gold wire: SR-Y, high-loop wire; FA type, middle-loop wire; and GL-2, low-loop wire. All of these wires are composed of high-purity gold with various dopants added to obtain greater strength and stiffness. The three types of gold wire are gold alloys of 99.99% purity with less than 100 ppm of non-gold dopants. The major difference among these three types of wires is the concentration of calcium dopant: SR-Y, 1 ppm; FA, 6 ppm; and GL-2, 24 ppm. The effects of a calcium dopant on the thermomechanical properties of three types of gold-bonding wires were investigated. The sweep stiffness were measured for various bond spans and bond heights of three types of wire and was shown to increase with increased concentration of calcium.