Soldering of piezoelectric ceramics to copper stator elastomer for ultrasonic motor

Three kinds of solders, Sn-40Pb, Sn-3.5Ag and Sn-52In, were respectively used to join PZT8 piezoelectric ceramics and copper stator elastomer to test the vibration performance of different stators and analyze the effect of soldering pressure. The results show that with peak reflow temperature of 141 ℃, reflux time of 90 s and soldering pressure of 38.26-114.78 kPa, the stators joined with Sn-52In solder accompanying with rosin organic flux FS113A showed the best vibration performance. Under the excitation voltage whose peak-to-peak value was 80 V, the amplitude of the stators was 2.5 μm, which could reach the level of vibration of adhesive stator. The shear strength of soldered joint reached 6.88 MPa, exceeding the practical requirement of ultrasonic motor (≥5 MPa). It is expected to solve the aging problem of adhesive layer and thereby improve the service life of ultrasonic motor.