Reliability and Stress Analysis of Ink for Chip on Film Packaging

This paper investigates 2-D finite element analysis to determine the stress and strain distributions across the thickness of ink in single-lap joints. The results of simulations for 10 μm, 20 μm, 30 μm, and 40 μm thickness of ink are presented. Tensile peel and shear stress at the bond free edges change significantly across the thickness of ink, and the maximum shear and peel stresses occur near the overlap joint corner ends. Fourier transform infrared data indicated there was no water absorption in SN9000 ink after a pressure cooker test in which the parameters were 121°C, 100% relative humidity and 2 atm for 96 h. However, the thickness of tin varied when there were differences in the curing temperature. Looking at the experiment and predictions, the confidence level of the results is 91.4%. The findings of this paper help us to understand the relationship between the reliability and the operating temperature of SN9000 for curing temperature design.