Measurement of the thermomechanical strain of electronic devices by shearography

This paper deals with the optical measurement of strain in electronic power devices under normal operating conditions. This non-contact and non-invasive method called shearography is based upon speckle interferometry. The technique developed produces images of normal displacement gradient of devices. Numerical processing allows the determination of the surface displacement and its related strain. The main advantages of the measuring tool are to be a simple optical set-up, to be very robust with a good sensitivity and to measure directly strain. Therefore, it is well suited to fit into an industrial environment