MANUFACTURING METHOD OF METAL DEPOSITION FILM FOR FILM CAPACITOR

PROBLEM TO BE SOLVED: To obtain a metal deposition film for a film capacitor having high reliability with low initial failure.SOLUTION: A metal deposition film is formed by depositing a metal film on at least one surface of a polymer film, and safety mechanism margins are formed. The metal deposition film 18, in which the safety mechanism margins are formed, is then subjected to preheating by applying a DC voltage of 300-600 V between electrode rolls 23, 24 which hold the metal deposition film 18 therebetween while having a predetermined distance in the longitudinal direction. The distance L between the electrode rolls 23, 24 is 100-200 mm, the diameters D1, D2 of the electrode rolls 23, 24 are 80-100 mm , the film embrace angles 1, 2 of the electrode rolls 23, 24 are 90-180°, and the safety mechanism margins to which the processed dielectric breakdown sections belong are cut by a current flowing at the time of preheating.