| abstract |
A composite film for a film condenser, which comprises a biaxially oriented film made of polyethylene-2,6-naphthalenedicarboxylate as a main polymer component and an electrically conductive metal thin layer formed on the surface of the biaxially oriented film, wherein the number of flyspecks having an average diameter of 60 µm or greater in the surface of said biaxially oriented film is 20/m 2 or less and the number of portions failing to satisfy a dielectric breakdown voltage of 200 V/µm (electrical insulation defects) in said composite film is 20/m 2 or less, and a biaxially oriented film therefor. n According to the present invention, there is provided a high-quality composite film for a film condenser, which has excellent physical properties and electric characteristics. Further, there is provided a very thin biaxially oriented film excellent in processability and surface properties and usable for the composite film. |