Behavior of anisotropic conductive film joints bonded with various forces under temperature fluctuation

The effects of bonding force and temperature fluctuations on the failure behaviors of anisotropic conductive film (ACF) interconnections were analyzed. Thermal shock testing was conducted to realize the temperature fluctuation environment. Two primary modes of failure were detected after thermal shock testing: formation of a non-conductive gap between conductive particles and the Au bump or Ni/Au-plated Cu pads, and delamination of the adhesive matrix from the plated Cu pads on flexible substrates. The failure mode was affected mainly by the variation in the bonding force. The main failure mode of the thermally shocked ACF joints was the non-conductive gap for the joints with low bonding forces and adhesive matrix delamination for the joints with high bonding forces. The difference in failure modes is critically discussed.