Property of Cu and PbSrZrTiO3 multilayer actuator fabricated by cofiring with wet reduction

Traditional co-firing processes involving noble metals are costly, thereby prompting a shift to base metals, such as Cu, to reduce manufacturing expenses. This study explored the use of Cu as an internal electrode for fabricating piezoelectric multilayer devices using a Pb0.98Sr0.02(Zr0.48Ti0.52)O3 (PSZT) ceramic material. The compatibility of Cu with PSZT in ambient air and the subsequent wet-reduction was investigated. The addition of polyvinylidene fluoride (PVDF) to the Cu electrode expedited the reduction process; however, this prompted void formation. Thus, epoxy resin was injected to post-reduction to enhance its mechanical property and address this issue. The impact of the PVDF content on the reduction rates, microstructure, and electrical/mechanical properties was analyzed. The experimental results highlighted the successful fabrication of Cu/PSZT devices with performances comparable to those of traditional noble metal (AgPd) counterparts. The polarization and strain of the Cu/PSZT device with 10% PVDF were comparable to those of the AgPd/PSZT. Subsequently, the incorporation of epoxy resin and Cu electroplating greatly improved the mechanical strength of Cu/PSZT to values comparable to that of AgPd/PSZT, as confirmed by the successful fabrication of a piezoelectric ultrasonic device and vibration measurement at 60 kHz. Therefore, this proposed process is a viable alternative for fabricating low-cost and stable multilayer ceramic devices.