Dielectric breakdown toughness from filament induced dielectric breakdown in borosilicate glass

The dielectric breakdown strength of borosilicate glass was measured as a function of the length of a conducting filament in order to determine the critical energy release for the growth of a breakdown channel. The concept is similar to the experimental determination of the toughness in fracture mechanics and based on a Griffith type model for the electrical energy release rate in dielectric materials with space charge limited conductivity. By Focused-Ion-Beam-milling and Pt-deposition, up to 100 mu m long conductive channels were fabricated in 163 mu m thick borosilicate glass substrates. The dielectric breakdown strength of substrates with filaments longer than 30 mu m could be very well described by a 1/root filament length-dependence predicted by the model Schneider, 2013. With filament length these results for the first time a critical energy release rate for dielectric breakdown was determined being 6.30 +/- 0.95 mJ/m.