DC breakdown characteristics of high temperature polymer films

This paper shows the effect of electrode area on dielectric strength for different polymeric materials. In the investigation, four electrodes of different diameters are selected in the range of 12.5-50 mm. To develop a base of understanding, several commercially available dielectric materials of different thickness that have been studied are aramid paper (Nomexreg) polyimide film (Kaptonreg) Mylarreg polyester film, PTFE, Nomex-Mica, and Nomex-polyester-Nomex composites. The DC breakdown strength of these high temperature dielectric materials is investigated by using the two-parameter Weibull distribution. It is noticed that the lower thickness films are more susceptible to the mechanical damage during handling process, thus increasing the chances of having lower breakdown strength. This lower breakdown strength cannot be ignored for effective insulation design of electric power apparatus and for the high reliability that is desired in the sensitive devices such as microelectronics, fiber optics, and in outer space applications