High temperature dielectric properties of Apical, Kapton, PEEK, Teflon AF, and Upilex polymers

Apical, Upilex, Kapton, Teflon AF, and PEEK polymers are characterized for AC and DC dielectric breakdown in air and in silicone oil at temperatures up to 250°C. The materials are also tested in terms of their dielectric constant and dissipation factor at high temperatures with an electrical stress of 60 Hz, 200 V/mil present. The effects of thermal aging on the properties of the films are determined after 15 h of exposure at 200 and 250°C. The preliminary data indicate that most of the tested films remain relatively stable when exposed to temperature as high as 250°C. The PEEK film however tends to display some wrinkling and exhibit discoloration when exposed to temperatures of about 200°C and higher. All other films displayed good dielectric and physical properties even up to 250°C