DocumentCode :
1411710
Title :
Statistical analysis of electrical breakdown behavior of polyimide following degrading processes
Author :
Li, L. ; Bowler, N. ; Hondred, P.R. ; Kessler, M.R.
Author_Institution :
Dept. of Mater. Sci. & Eng., Iowa State Univ., Ames, IA, USA
Volume :
18
Issue :
6
fYear :
2011
fDate :
12/1/2011 12:00:00 AM
Firstpage :
1955
Lastpage :
1962
Abstract :
Polyimide (PI) tape has been widely used as electrical insulation for wires and cables due to its excellent balance of electrical, mechanical and thermal properties. However, insulation materials are exposed to various environmental degradation mechanisms during service, which can cause deterioration of their insulation properties. In this paper, the effects of thermal exposure and immersion in water on dielectric strength of Kapton® HN PI film are investigated statistically by two-parameter Weibull distribution analysis. The PI samples were heated at 475°C for 1 to 4 h, and at 450 to 480°C for 4 h, to study the influence of thermal exposure. Moreover, to explore the effect of moisture absorption, other PI samples were immersed in distilled water for up to 96 h at room temperature. After the degrading process, breakdown voltage and thickness were measured at 20 different points on each sample. The Weibull cumulative distribution function for each of the degraded samples was plotted, and compared with that of a sample dried by heating at 200°C for 1 h. Significant decreases in both the scale parameter and the shape parameter of the Weibull distribution, obtained through least-squares regression, are observed, indicating a statistical decrease in dielectric strength and a more dense dispersion of electrical weak points in PI. This observed deterioration of insulation capability of PI is attributed to chemical degradation and formation of ionic side groups during heating and immersion in water, respectively.
Keywords :
Weibull distribution; electric breakdown; electric strength; organic insulating materials; polymer films; regression analysis; Kapton; Weibull cumulative distribution function; Weibull distribution analysis; breakdown voltage; degrading processes; dielectric strength; electrical breakdown behavior; electrical insulation; electrical properties; environmental degradation mechanism; immersion; insulation materials; ionic side groups formation; least-squares regression; mechanical properties; moisture absorption; polyimide tape; shape parameter; statistical analysis; temperature 200 degC; temperature 293 K to 298 K; temperature 450 degC to 480 degC; thermal exposure; thermal properties; time 1 h to 4 h; Chemicals; Dielectric breakdown; Dielectric measurements; Heating; Temperature measurement; Weibull distribution; Weibulldistribution; dielectric strength; electrical breakdown; immersion in water; polyimide; thermal exposure;
fLanguage :
English
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
Publisher :
ieee
ISSN :
1070-9878
Type :
jour
DOI :
10.1109/TDEI.2011.6118633
Filename :
6118633
Link To Document :
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