The coupling effects of temperature, electric current and stress on the adhesion and electrical properties of COG assembly

Abstract

This paper reports the adhesion and electrical properties of chip-on-glass (COG) assembly undergoing the coupling loads of temperature, electric current and stress (hygrothermal stress or thermal stress). Firstly, the effects of loading rate and coupling loads on the adhesive force of COG assembly were studied by shear test. The maximum shear force of COG assembly firstly increases and then decreases with increasing loading rate in range of 10–70μm/s, peaks at the loading rate of 50μm/s. When the COG assembly was exposed in the coupling loads of temperature, electric current and hygrothermal stress, its maximum shear force decreases with the increase of hygrothermal aging time. However, as for thermal cycling aging time increases, the maximum shear force increases initially and then decreases for the COG assembly under the coupling loads of temperature, electric current and thermal stress. The functions of the maximum shear force with aging time were obtained by fitting experiment data. Secondly, the real-time resistances of COG assembly during shear test and aging process were detected using two-point probe. In shear process, the real-time resistance increases insignificantly in elastic deformation stage but increases rapidly in viscoelastic deformation stage prior to the fracture. Due to the combined influences of temperature, electric current and stress, the resistance increases remarkably with the increase of hygrothermal aging time and it increases slightly with the increase of thermal cycling aging time. However, the real-time resistance exhibits circulation changes corresponding to thermal cycling. Finally, the relationship of resistance with the maximum shear force of energized COG assembly versus environmental aging times was studied.