Thermal Image Analysis of Conductive Joints of Flexible Printed Circuit (FPC) using Anisotropic Conductive Films (ACF) Bonding

Abstract

This study is based on the thermal image measurement technology, aiming at the experimental record of the transient process of heat generation, heat dissipation and heat stability of the conductive ball's resistance through current conduction for the Anisotropic Conductive Film (ACF) assembly specimen after the bending load. The test vehicle of flexible printed circuit (FPC) is conducted by the thermos-compression bonding of the flexible circuit and the transparent substrate (PET / coated ITO) using ACF. The conductive balls in the ACF will be compressed and rupture during the thermos-compression process, and then play the role of electrical conduction. However, after the FPC assembly are subjected to different bending loads, the conductive balls may cause severe cracking or crushing, which will lead to an increase in the resistance of the conductive balls. The thermal image records of this research can be used to obtain the resistance variations before and after loading. Finally, the bending resistance and electrical conduction quality of the ACF can be evaluated by the temperature distributions and average temperature values after the conductive joints resistances have stabilized heat dissipation.