Stress analysis of interconnect structure in COF by finite element method

Stress analysis is of crucial importance in the process development of non-conductive film (NCF) and Au-Au thermo-compression bonding for chip on foils. In this paper, the authors present the finite element simulation results of chip on foil process with emphasis on the effect of interconnect structure, in particular on the stresses in the Al layer in the IC pads. Track width and misalignment were two main factors studied. The former affects the foil and interconnect design; while the later is related to manufacturing tolerance and bonding machine accuracy. It is shown that the bonding force, track width and misalignment have great influence on the, maximum stress in the aluminum layer of the IC bonding pads. The simulation results are compared with the experiments. Good agreement on the crack location was demonstrated.