Lead-Free Flip Chip Package Reliability and the Finite Element-Factorial Design Methodology

As is well known, the design parameters of the packaging material and structure greatly influences the reliability of the packaging. When it comes to flip chip packages, the feeling is that it are the parameters that cause the complicacy of the package reliability design. In addition, the interactions between these different design parameters remain unclear, especially for the lead-free solder applications. Based on the above, the FEM factorial analysis was employed in this research to investigate the interrelationship of the design parameters. The factorial design method was repeated twice with two solder materials (63Sn/37Pb and 96.5Sn/3.5Ag). The findings show that the structures with a larger BT core thickness, a thicker pre-solder layer and a higher bump height have a better solder bump reliability. In terms of the factorial analysis, the BT core thickness was the factor having the most influence on reliability. The interactions between the factors were observed in this study