Abstract
The present study has been designed to characterize small voids, due to the Kirkendall effect, in the neighborhood of bonding interface in the Cu⁄Ni clad metals for micro-batteries. These small voids, being the source of destruction, could harm the electric resistance and the heat conductivity, both of which are important factors of the products. The method employed in this study is the ultrasonic technique with immersion type focused transducer and signal processing. We focused on the discrimination between the two adjacent pulse echoes from the bonding interface and void layer and also on identifying the void signal by means of wavelet transform analysis with Coiflet wavelet as mother one. It was experimentally confirmed that the ultrasonic method presented here has been successfully applied for evaluation of the Kirkendall voids in the Cu⁄Ni thin clad metal sheets.
