| Popis: |
Air Force currently has a strong need for the development of compact capacitors which are mechanically robust and thermally stable for operation in a variety of aerospace power conditioning applications. These applications demand better reliability and flexibility in the power system design as well as decreased thermal load for electronic system cooling. While power conditioning capacitors typically use polycarbonate (PC) dielectric films in wound capacitors for operation from -55 deg C to 125 deg C, future power electronic systems would require the use of polymer dielectrics that can reliably operate at elevated temperatures up to or even exceeding 350 deg C. The focus of this research is the generation and dielectric evaluation, up to 350 deg C, of metallized free-standing thin films derived from high temperature polymer systems such as fluorinated polybenzoxazoles (6F-PBO) and fluorenyl polyesters incorporating diamond-like hydrocarbon units (FDAPE). The discussion will be centered mainly on variable temperature dielectric measurements of film capacitance, dissipation factor and insulation resistance, and the effects of thermal cycling on film dielectric performance. Initial studies clearly point to the dielectric stability of these films for high temperature power conditioning applications, as indicated by relatively minor variations (~ 2 %) in measured film capacitance over the entire range of temperatures studied. Comparison will also be made with the reported variable temperature dielectric properties of the state-of-the-art high temperature FPE films. |
