Stress-strain curves of flip-chip solder balls based on finite-element modeling of thermal displacements measured by electronic speckle pattern interferometry

Electronic speckle pattern interferometry (ESPI) was applied to noncontact, real-time evaluation of thermal deformation in a flip-chip solder joint. To measure the deformation of such tiny components as the solder balls in the flip-chip, the spatial resolution of ESPI was increased to submicron scale by magnifying the areas studied. Experimental-computational procedures were developed to obtain stress-strain curves for solder balls in the flip-chip based on finite-element modeling (FEM) of in-plane ESPI thermal displacement data. The stress-strain curve obtained for the flip-chip solder was compared with those for bulk solder. The microstructure was also studied to clarify the stress-strain curve results.open2