Fabrication of sol-gel modified piezoelectric thick films for high frequency ultrasonic applications

In this work, a fabrication process of piezoelectric PZT thick films up to 60 μm deposited on silicon and aluminum substrates is reported. Crystalline spherical modified PZT powder about 0.3 μm in diameter was used as filler. PZT polymeric precursor produced by Chemat Incorporated was used as the matrix material. Spinning films were annealed at 700°C in the furnace for half an hour in air. The thickness of the thick films: was measured using a scanning electron microscope (SEM). Compared with previous piezoelectric PZT composite films, the modified piezoelectric thick films exhibit very good dielectric properties. The dielectric constant is over 780 and dielectric loss is 0.04 at 1 kHz. Using a PiezoCAD model, the high frequency transducer was designed and fabricated. It showed a bandwidth of 75% at 40 MHz.