Morphology and dielectric properties of uniaxially and biaxially-oriented polycarbonate capacitor films

Abstract

A reflective X-ray diffraction method developed to determine the absolute X/sub c/ (crystallinity) of UX and BX (uniaxially and biaxially oriented) PC (polycarbonate) film is described. Conditions for achieving optimum properties for producing BX high-X/sub c/ and isotropic PC film were found. For BX PC film of identical thickness to UX PC film the electric breakdown strength was found to be proportional to X/sub c/. The thermal and mechanical properties as well as the direct-current electric breakdown strengths of the newly developed isotropic high-X/sub c/ BX PC film are compared with those of the anisotropic commercial PC capacitor film. Capacitors made from the high-X/sub c/ isotropic BX PC film when subjected to a 1000-hour 100 degrees C, 42-V DC life test showed no change in dissipation factor and no change in capacitance, and they met 100 degrees C insulation resistance test requirements. In general, it is concluded that this novel BX PC film is much superior to the traditional UX commercial capacitor PC film.<>