In this work, thermal-mechanical leadframe strain in an electrically active IGBT was measured using electronic speckle pattern interferometry (ESPI). ESPI is a non-contact optical technique capable of high resolution surface displacement measurements. The significant contribution of this paper is an experimental methodology by which strain can be measured in electrically active devices. A 3-D ESPI test stand was developed, combining two cameras to simultaneously capture the local (interconnect level) and global (device level) displacements. Through the combination of incremental sub-loads and mathematical recorrelation of speckle patterns, device power loads have been measured (which would have been otherwise impossible due to speckle decorrelation, which limits measurement of large deformations). A model-based tracking technique was developed from coupled experimental noise measurements and FE modeling - allowing for optimal strain solution to be extracted from noisy displacement results. The developed and experimentally-validated thermal-mechanical FE strain model agreed to within 7% of ESPI strain measurements.
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