Development of photo-sensing bulge ductility tester

The ductility of thin films is normally evaluated by conducting the bulge testing. However, the accuracy of the conventional type of mechanical bulge ductility testing unit is poor in determining the actual elongation. In this development, a photo-sensitive device is provided in the detecting portion to accurately measure the elongation. The sensitivity depends on the type of the materials tested. A Pyrex glass ball is utilized as a punching ball to provide equally distributed light. Pushing of the Pyrex glass is activated by a hydraulic media to control the punching velocity. Accuracy and reproducibility were primarily checked with copper thin foil deposited on polyimide substrates. Two types of dental articulating papers (paper-based and plastic-based) were tested. It was suggested that an appropriate selection of articulating paper to mark the occlusal interferences is essential for precise determination of occlusal harmony.