ESPI Analysis of Thermo-Mechanical Behavior of Electronic Components

Thermo-mechanical aspects must be conveniently taken into account when designing electronic components and devices. Reliability issues can in fact arise due to stress induced by thermal field acting on materials with different coefficients of thermal expansion. In this paper an optical system based upon Phase Shifting Electronic Speckle Interferometry (PS-ESPI) was developed; it allows analyzing the in-plane displacement map experienced by the tested component during its working operation as a consequence of the Joule's effect. The adoption of an optical technique allowed to get the measurement without contact with the component that is to say without altering the capability of thermal dissipation of the component. The system was demonstrated to be effective in analyzing asymmetries in the displacements along the component and in evaluating how different kinds of constraints can drastically affect the thermo-mechanical behavior of a given component. Furthermore the system was used to compare the thermo-mechanical response of the same component in presence or in absence of a critical defect. It was verified the ability of the set up designed to detect the very different thermo-mechanical response of a damaged electronic component with respect to an undamaged one.