A microslip model of the bonding process in ultrasonic wire bonders part II: steady teady state response

Ultrasonic wire bonders with precision capillary tips are widely used for bonding electrical wires to IC chips and circuits. The industry is driving wire-bonding technology towards increased yields, decreased pitch, and ever decreasing cost. However, many technical and material issues will be involved in achieving these goals, such as bond quality monitoring, new failure modes, reliability problems in new plastic mold compounds, and increasing wire sweep problems, in particular lack of the quantitative understanding and validated mathematical model of the bonding process. In a previous paper [Hu CM, Guo N, Du H, Li WH (in press) A microslip model of the bonding process in ultrasonic wire bonders - Part I: transient response. Int J Adv Manuf Technol], a microslip model has been proposed for bonding process based on the bonding pattern observed, i.e. the wire is bonded at the periphery while the centre is left unbonded. A bilinear hysteresis restoring force is assumed in a microslip model because of its simplicity. The predicted transient responses show good agreement with the experiment. In this paper, the analysis is extended to steady- state response, and discussion and comparison are made with respect to the transient response.