Mechanical Behavior Measurement of Electronic Devices by Moiré Interferometry under Thermal Cycle Test

Abstract

Electronic devices, which are composed of materials of different thermal expansion coefficients, are subject to thermal deformation because of thermal cycling, and the strain induced by mismatching due to deformation leads to fatigue failure. To avoid strain concentration, the finite element method plays an important role in packaging design. However, non-linear behavior due to different thermal expansion coefficients and creep behavior of the solder bump make accurate prediction of failure difficult. Consequently, it is essential to estimate the results of analysis obtained by the finite element method. In this study, we measure real-time thermal displacement and strain distribution under thermal cyclic loading test by the Fourier transform Moire method with the carrier pattern technique, and then extract creep behavior, residual strain, and also the effect of multicyclic loading, which are not predicted by the finite element method. To evaluate not only the behavior of the cross section but also that of whole devices, we measure out-of-plane displacement by means of the Moire interferometry.