Impact of Package Warpage on Package Strength Assessment Under Three-Point Bending Test

Package strength is important to ensure package quality and reliability during assembly process and field application. Three-point bending (3PB) test is usually used to assess package strength. Finite element analysis (FEA) is a powerful tool to evaluate package strength and help design optimization to improve package strength. In the traditional FEA simulation, the package is assumed as flat without considering package warpage before it is subjected to bending load. However, packages have different warpage shapes and values at room temperature in the real situation. It is lack of study of package warpage effect on package strength. Therefore, effect of package warpage (shape and values) on package strength is simulated and discussed in this study. The results show that warped package leads to less failure force than flat package. However, if using package surface strain as a criterion, effect of package warpage on package strength becomes not significant, which verify that assuming package as flat will not bring big error for package strength assessment with using strain criterion. Considering residual stress on Si die for package strength assessment is another novel method and significant contribution on understanding package strength difference with using different molding compound materials.