EPC is putting a strong focus on proofing the reliability of their GaN technology. Therefore their devices are tested for failures under extreme voltage and current stress.
Standard qualification tests for semiconductors typically involve stressing devices at-or-near the limits specified in their data sheets for a prolonged period of time, or for a certain number of cycles, with the goal of demonstrating zero failures. By testing parts to the point of failure, an understanding of the amount of margin beyond the data sheet limits can be developed, but more importantly, an understanding of the intrinsic failure mechanisms of the semiconductor can be found.
Read here the full article written by Alex Lidow Ph.D., CEO and Co-founder, Efficient Power Conversion
If you want to read more about this read here the news report.