High spatial resolution measurements of thermo-mechanical stress effects in flip-chip packages

This work focuses on the experimental evaluation of thermo-mechanical stress induced in flip-chip BGA packages. The proprietary Si chip with integrated piezoresistive stress sensors is used to electrically measure chip package interaction (CPI) effects with high spatial resolution of 5μm. The electrical measurements are supported by finite element modeling which consecutively simulates different assembly steps such as flip-chip, application of underfill (UF), molding, and uses the experimentally determined thermo-mechanical properties of the packaging materials.