Characterization of the fatigue properties of bonding wires

Bonding wire fatigue reliability is one of the key issues in PPGA (and other cavity type packages) wire bonding process development. This paper describes a unique technique to measure the fatigue properties of bonding wires for IC interconnections. This system allows for long lengths of wire to be strained in bending by wrapping the wire around two mandrels in sequence; the diameter of the mandrels determines the strain at the surface of the wire. Long lengths of wire are managed by winding the wire on 3-inch take up reels of Teflon. Testing at elevated temperatures is accomplished by heating the entire machine. The results of this work clearly show differences in fatigue properties between three types of bonding wire.