Modification of polypropylene films for thin film capacitors by ion implantation

Polypropylene (PP) films for thin film capacitors were implanted with N, Ar, and Ne, respectively, in order to reduce the water vapor permeability. It is shown that the reduction of the water vapor permeability strongly depends on implantation dose and energy. For doses below 10¹⁵ cm^-2, the water vapor permeability was not affected, while doses above 10¹⁵ cm^-2 lead to a significant reduction. For all of the mentioned elements, 10 keV implants lead to a significantly greater reduction than 20 keV implants. The largest reduction of about 96 % was achieved by Ar implantation at 10 keV and a dose of 10¹⁵ cm^-2. Besides the water vapor permeability analysis, surface analysis, tensile tests, and electric strength measurements of implanted and nonimplanted films were performed and are discussed in the paper.