Using fast response detecting and recording equipment the breakdown voltage spectra of thin film dielectrics (with a GdCoMo first electrode and permalloy counter-electrode) were measured as a function of time and temperature during application of linearly increasing (ramp) voltages. For 1000 A thick.SiO, films the dielectric breakdown events occurring at high voltages were seen to be strictly voltage-dependent, whereas those breakdowns occurring at low voltages exhibited a definite time-dependence in addition to a voltage-dependence. In this low voltage region slowly increasing voltages (low ramp rates) resulted in significantly greater numbers of cumulative failures, for a given attained voltage, than did rapidly increasing voltages. This time-dependence, transformed through a simple kinetic power law to a constant applied voltage experiment was found to be consistent with Peek's law of dielectric breakdown. The data and analysis suggest that reliable device operation will not be achieved if electric fields in excess of 0.6 x 106 V/cm are applied across the dielectric. © 1975, IEEE. All rights reserved.