Degradation mechanisms of anisotropic conductive adhesive joints for flip chip on flex applications

Flip chip on flex (FCOF) using anisotropic conductive film (ACF) has been demonstrated. Two types of conductive particle in ACF are used in this paper to investigate the effect of pinholes of the the electroless nickel bumps on electrical connection of ACF joints of FCOF samples. The conduction mechanisms of both types of ACF joint due to the effect of pinholes have been discussed. After high temperature and high humidity storage, Ni filled and Au/Ni coated polymer filled ACF joints using non-aged or aged bump chips show slightly and dramatic increases in connection resistance respectively. Detail degradation mechanisms for these ACF joints have been proposed.