With the numerous applications of thin films, the mechanical properties of thin films are becoming increasingly important. Of these, the fact that internal stresses exist in thin films has been known for over a hundred years. Stresses in evaporated thin films have been a topic of study by many workers and many good reviews have come out (1.2). Besides the internal stress, the thermal stress arising out of the difference in thermal coefficient of expansion of the substrate and film material also becomes important. Though much data is available for internal stress in thin films, the data for thermal stress is scanty. It is in this context a study has been undertaken to set up a novel technique of measurement of thermal stress of thin films using real-time holographic interferometry. Using this technique thermal stress in conductive coatings has been studied and some results on iron and copper films are presented.
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