Study on Aging Characteristics of Polyimide Film Based on Dielectric Loss

In this paper, accelerated aging test was conducted on polyimide (PI) film under the conditions of electrical, thermal and electrical-thermal stresses. In the period of aging, four polyimide film samples were tested and the value of tan δ and sample capacity were measured by DELTA-2000 and HIOKI3532-50LCR to investigate influence of tan δ and capacity under different aging additions. According to the analysis of the experiment data, it definitely indicates that the physical process of capacity with aging time was identical with analysis of experimental result of dielectric loss. Electrical aging plays the most important role in affecting tan δ, and thermal aging leaded to decreasing of tan δ as the function of thermal cleaning in some degree. According to dielectric spectrum analysis, it was suggested that the peak point of tan δ curve under different frequency could be used to describe the aging characteristics of insulation.