Heating Temperature Profile Optimization in Flip-Chip Surface Mount Technology

Abstract

Metal bumps are used to connect Si chip to printed circuit board in Flip-Chip surface mount technology. These Bumps are sometimes broken by thermal stess due to thermal expansion difference of Si chip and printed circuit board. Thermoset adhesive is used in order to prevent bumps from breaking. Thermoset adhesive is filled between Si chip and printed circuit board and heated to be cured. The bubble of gas occures from heated printed circuit board in this process. The viscosity should be kept low in the earier process in order to exhaust bubble from thermoset, although the viscosity becomes higher in the hetaing process by cure reaction. In the other hand, the terminal cure reaction rate should be high in order to ensure reliability of adhesive. In this study, the viscosity and cure rate are modelled as functions of time and temperature. By using these models, heating temperature profile of this process is optimized in order to avoid bubble and ensure reliability of adhesive.