Investigation of breakdown values and charge storage properties of PVDF

The breakdown values and charge storage properties of thin-film PVDF (polyvinylidene fluoride) were investigated with a view to the possible manufacture of small volume, high-energy-density capacitors for use in medical implant devices. The dielectric breakdown fields of 3.5- mu m- and 6- mu m-thick films of PVDF have been measured using a field which increases linearly with time. The rate of rise of the electric field varied from 3 MV m/sup -1/-s/sup -1/ to 1000 MV m/sup -1/-s/sup -1/ at room temperature. Experiments were carried out both in air and silicone oil. For both film thicknesses, the breakdown fields show a maximum at a field rate of approximately 120 MV m/sup -1/, the value being slightly higher for the thicker film. For rates both above and below this value, the observed breakdown field decreases. In oil the breakdown strength increases with increasing rate of field rise to approximately 140 MV m/sup -1/. At higher rates the breakdown strength remains constant. In oil, as in air, the breakdown strength is higher in the thicker film.<
>