(A) study on Non-Conductive Film (NCF) materials and bonding conditions for high-speed Cu Pillar/Sn-Ag hybrid-bump bonding

Abstract

Electronic packaging industry is demanding the value of high density, high performance and small packaging size moving toward fine pitch technologies. Especially, in Chip on Board (COB) interconnection, the fine pitch technologies such as NCF of future adhesive material and Hybrid-Bump, typical bump structure for 3D Through Silicon Via (TSV) have been studied as connection methods. However, as these fine pitch technologies are sophisticated, they are disadvantageous in that they require a long processing time. The conventional COB interconnection method takes very long time because it needs three steps of aligning, bonding, cooling. During the bonding step, the process of raising the temperature by applying heat is very slow, and the cooling step takes the longest time. Therefore, there is a limit to the speed of production. However, in this study, a new method (High-Speed Bonding) was introduced which can proceed the bonding process for a very short time using a pre-heated bar. High-Speed bonding is very fast at the rate of heat-up in bonding step. Also, because of distinction between bonding equipment and aligning equipment, it does not require the cooling step, which can greatly improve the productivity. So, this new interconnection method, High Speed Boding was applied to the NCF and Hybrid-Bump for fine pitch implementation. First, the optimization of NCF and bonding conditions for High-Speed Bonding was performed. And then, it was applied to the Hybrid-Bump structure and the characterization of interconnection joint and reliability test was performed. Ultimately, the feasibility of High-Speed bonding in fine pitch was explored.