Quantitative strain analysis of flip-chip electronic packages using phase-shifting moire interferometry

In order to gauge the reliability of electronic packages, it is valuable to analyze thermally induced displacements and strains around bimaterial corn ers and within interconnections. The increased demand for computing perform ance has created increasingly complex electronic packages with miniaturized features, making it increasingly difficult to extract these quantities. Of ten. material properties at these length scales are not fully known, making modeling and simulation problematic. Thus, determining displacements and s trains experimentally is attractive. In this study. an advanced flip-chip p ackage with fine interconnection features was analyzed using phase-shifting moire interferometry (PSMI) in conjunction with image analysis software de veloped for this purpose. Before the analysis, PSMI was qualified using an isotropic solid undergoing uniform thermal contraction. which yielded a dis placement precision of +/-4 nm. Then a high-magnification, high-resolution displacement and strain analysis was performed for a small cross-sectional region of the flip-chip package containing 20-100 mum sized features, The a nalysis quantifies these results and gives displacements and strains obtain ed by differentiating the displacement data using a strain-energy-based fin ite element formulation. (C) 2001 Elsevier Science Ltd. All rights reserved .