Development of a mathematical model for thermal-compression bonding of the COG packaging process using NCA

In this decade, many new techniques have been introduced into the integrated circuit (IC) packaging industry. Packaging technology used in liquid crystal displays (LCDs) has requirements related to critical issues such as high density interconnects, thinner packaging size, and environmental safety. Driver IC chips are directly attached to LCD panels using flip chip technology with adhesives in the so called chip on glass (COG) packaging processes. To investigate the dependence of the bonding force on the bump deformation during packaging, this study established a mathematical model to analyze COG packaging processes with non-conductive adhesives (NCAs). The plastic deformation of the bumps and the NCA flow between the chip and substrate are taken into account in this model. With this model, the contact resistance and the gap height after bonding can be estimated for different bonding force.