In June 2009, EPC introduced the first enhancement-mode Gallium Nitride (eGaN) FETs designed specifically as replacements for power MOSFETs. These products were designed to be produced in high volume at low cost using standard silicon manufacturing technology and facilities. Thirty years of silicon power-MOSFET development taught EPC that one of the key variables controlling the adoption rate of a disruptive technology is whether or not the product is reliable enough to use in the application. This principle has guided the design of EPC’s eGaN FETs. To explain the devices’ reliability, it is necessary to first review how they operate and highlight both their similarities and differences vs. today’s power MOSFETs. With that as background, this presentation will describe the reliability tests that were performed and the results achieved for EPC’s first-generation eGaN FETs. The goals of a qualification program are two-fold: (1) to continuously drive optimization in device design, manufacturing, and material growth; and (2) to meet and exceed the reliability levels that designers have come to expect from silicon MOSFETs. The primary source of data was the testing of large populations of parts, over long time intervals, under the same stress conditions that are industry standard for silicon devices. The qualification testing reported here follows industry standards. To pass, all device parameters must stay within datasheet limits.