Effects of Vapor Phase Soldering on the Properties of Piezoceramic Materials

Eight different PZT (lead zirconate titanate) materials (Navy Type I and II) with Curie temperatures between 250 °C and 350 °C were subjected to a standard vapor phase soldering process with a peak temperature of 240 °C for three cycles. As indicators for the depolarization, the piezoelectric charge coefficient (d33) and the coupling coefficient (keff) were measured both before and after each heat treatment. Our studies demonstrate reductions in piezoelectric properties between 5% and 20%, depending on the Curie temperature of the corresponding material. The effects of the second and third cycle were minimal. The drop in performance, especially for materials with higher Curie temperatures, is moderate, and can be accounted for in the design of the device. Thus batch soldering processes become a viable alternative to selective soldering.