A simple transducer model for longitudinal flip-chip bonding

A simple phenomenological model has been developed capturing the main dynamical features of longitudinal flip-chip bonding processes in electronic packaging. The transducer is modeled as a rod-type continuum with unilateral contact conditions enabling to simulate intermittent dynamic contact. The electronic chip together with the bumps and the substrate are represented by a visco-elastic foundation model. A Galerkin-discretization is carried out to project the spatial deformation of the continuum transducer model onto the most important vibration modes. A model analysis shows the dependence of the frequency response plot of the transducers tip vibration amplitude on the axial preload. Furthermore, the behavior of the contact force acting on the chip is examined as well. First experimental analysis clearly show, that jump phenomena may occur during the bonding processes. The results give new insights into the concept of ultrasonic longitudinal bonding.