Optimization study on underfill for high density packaging with numerical analysis

We reported the material properties, that we use in the numerical analysis, controls the quality of the analysis result directly in our previous paper. In this paper, we focus on the optimization of underfill for the high density packaging such as consumer electronics devices. We report the methodology to optimize the underfill properties through some parameter studies with numerical analysis. It seems to be difficult to define the best underfill to be used for the high density packaging. In this study, some currently available underfills and the newly developed one are applied into WL-CSP (Wafer Level Chip Sized Package) to compare the reliability of the package by the stress and strain caused at both solder and underfill under thermal stress.