Experiments using the Design of Experiment (DoE) methodology were carried out to investigate the effects of pitch distance (P), temperature (T), voltage (V), and contamination (C) on the leak current measured on surface insulation resistance (SIR) test boards. A 2 4 full factorial design with eight replications was performed, and the response was measured continuously over a 20 hour period for each experiment. Current measured over time exhibited a clear pattern of an initial low and stable current, followed by a transition to a much higher current. Microscopic analysis of the boards indicates that the transition is due to dendrite formation due to electrochemical migration (ECM). The time at the start of this transition phase was identified as the time to failure (TTF) for each experiment. Leakage current (LC) was also calculated as the mean current prior to failure. Analysis of Variance methods were used to model both TTF and LC. Both TTF and LC were found to be significantly affected by P, T, and C. However, the effect of V was found to be significant only for TTF. The general current behavior over the prolonged experimental period and the resulting statistical models give new insight into the failure process related to ECM.