Chapter 40 ESPI Analysis of Thermo-Mechanical Behavior of Electronic Components C. Casavola, G. Pappalettera, and C. Pappalettere Abstract 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 Interferom- etry (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. Keywords ESPI • Electronics components • Thermal field • Defect detection 40.1 Introduction Electronics has deeply contributed to the great development of modern technological systems and is now used almost everywhere. Designing new electronics components or also new electronics packages is a complex task entailing issues about materials and processing, electrical performances and thermo-mechanical behavior [1]. This last aspect is also strictly connected with reliability performances of the component itself. In fact an electronic component is a complex object made by the superposition of different layers with different coefficients of thermal expansion; the presence of a thermal field can then result in a stress field that can cause delamination of the structure and, as a consequence, the mechanical breaking of the components [2, 3]. Nowadays the continuous push towards reduction in size and weight of electronics device leads to the use of high-density packaging where thermo-mechanical issues are even higher due to limited volume for thermal dissipation [4]. Quite recently interferometric optical techniques (OT) have been introduced in the analysis of electronic devices [5]. Generally speaking, OT are based on the modulation of a light wave front that interacts with the specimen surface. The modulation leads to the formation of a pattern of fringes encoding full-field information on the displacement field experienced by the specimen surface. Strains can be either obtained optically or through differentiation of displacement fields. OT were successfully applied in a variety of fields in experimental mechanics [6–10] and in view of their capability to get the full-field map of deformations with high sensitivity, no contact and in a non-destructive way [11–15] they appear to be of great interest for characterizing the thermo-mechanical response of an electronic component [16–19]. High sensitivity, in fact, has to be a basic requirement of the measuring system because of the magnitude of the deformations involved. The absence of contact, moreover, warrants that no alteration occur in the thermal dissipation of the elements examined and avoid errors related to the physical interaction between object and measuring instrument. This paper presents a PS-ESPI set up for the transient analysis of thermo-mechanical response of electronic components under different structural and constraint configurations. To that purpose, the mechanical behaviour of a fixed positive voltage regulator was analyzed to verify how its response and its deformation behavior can be affected by the adopted constraint configuration. It was also verified the ability of the system to detect the different mechanical response of an electronic component in presence or absence of defects; ESPI analysis were performed on the voltage regulator in its intact and, subsequently, damaged configuration. C. Casavola (*) • G. Pappalettera • C. Pappalettere Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Viale Japigia 182, Bari 70126, Italy e-mail: casavola@poliba.it; katia.casavola@poliba.it # The Society for Experimental Mechanics, Inc. 2017 S. Yoshida et al. (eds.), Advancement of Optical Methods in Experimental Mechanics, Volume 3, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-41600-7_40 321