Breakdown pattern identification in high temperature dielectric films using scanning electron microscopy (SEM)

In this research paper DC breakdown patterns identification were carried out after applying high voltages across samples of 25 /spl mu/m Kapton/spl reg/ (polyimide) and Mylar/spl reg/ polyester (poly(ethylene terephthalate), PET) films. For pattern identifications, Scanning Electron Microscopy (SEM) technique was employed for acquiring 150/spl times/ and 300/spl times/ magnified images. In both images the shape of breakdown area was almost identical to the shape of electrodes. The SEM results clearly revealed that the melting process during high voltage DC breakdown process is higher in case of Mylar/spl reg/ polyester than that of Kapton/spl reg/ (polyimide). In case of Mylar/spl reg/ at room temperature, observed hole diameter was approximately 265.5 /spl mu/m with the total effected area of 55.3/spl times/10/sup -9/ m/sup 2/ at DC breakdown strength of 326.7 MV/m as compared to Kapton/spl reg/, which was 155.7 /spl mu/m with total effected area of 19/spl times/10/sup -9/ m/sup 2/ at breakdown strength of 364.9 MV/m. In these films for the measurement of electrical breakdown strength a new type of environmental chamber was used. Two-parameter Weibull distribution has been used to analyze the results.