Fatigue and resistance analysis of COG modules using electro-mechanical coupling method

•The electro-mechanical coupling method for COG modules is utilized.•Different loading amplitudes seriously influence the relative resistance change.•Deteriorations of ACF bumps, micro-cracks and cavities affect fatigue life and resistance.

Due to the potential to provide finer pitch, smaller contact area, higher density, and higher pin–count interconnection of driver ICs in the LCDs, extensive investigations on the chip-on-glass (COG) progress have been carried out. However, there has been little research on the fatigue behavior of the COG modules using the electro-mechanical response. This paper investigated the resistance change and fatigue behavior of COG modules undergoing various mechanical loading. It is noted that the shear force prior to fracture is determined as 61.09 N, at which the resistance is found extremely high and can be regarded as open circuits. During the fatigue experiments, it is shown that the fatigue life of COG modules decreases with the increasing loading amplitudes and the Basquin’s equation agrees well with the experimental data. Moreover, the resistance changes instantaneously and periodically with the cyclically mechanical load, but the transient resistance change does not consist perfectly with the loading variation over a period of time. The higher the loading amplitude, the higher the relative resistance. In the meantime, the relative resistance prior to fracture increases firstly and then decreases with the increasing loading amplitudes as a result of the different extent of deteriorations of ACF bumps, different numbers of micro-cracks and cavities induced in material. The results provide guidance for the design, manufacture and development of the COG modules.