FABRICATION AND ELECTRICAL PROPERTIES OF PZT-PVDF 0–3 TYPE COMPOSITE FILM

ABSTRACT A film speaker was fabricated with 0–3 type piezoelectric composite. The 0–3 type composite was developed to incorporate the advantages of both ceramic and polymer. The pastes of PZT-PVDF composite were made with various mixing ratio. The paste was printed by conventional screen-printing method on ITO (Indium Tin Oxide) bottom electrode which was deposited on PET (polyethylene terephthalate) polymer film. The prepared composite film was about 80 μm in thickness. After printing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at 120°C for an hour to align the electric dipole in the 0–3 composite film. The piezoelectric charge constant of d33 was increased with increasing the PZT weight percent. The maximum value was 24 pC/N at 70 wt% of PZT. But the piezoelectric voltage constant of g33 had the maximum value about 32 mV · m/N at 65 wt% of PZT. The SPL (Sound Pressure Level) of the speaker fabricated with the 65:35 composite film was tested at various driving voltages of 1 ∼ 100Vrms. The SPL was saturated at the driving voltage of 70Vrms and the value was about 68 dB at 1 kHz.