Reliability Study of Microwave Power Transistors under Transient and Mismatched Loads.

摘要

This report presents the results of study of the reliability of current state-of-the-art transistors under non-ideal conditions, including output mismatch, excess collector voltage, and error drive. Four different device types were characterized to determine their electrical performance and junction temperature as a function of collector voltage, drive, and output impedance. Samples of the devices were taken to destruction under extremes of these variables and analyzed. It was observed that failure occurred when the junction temperatures exceeded a critical value, with the variables giving rise to the excess temperature making little difference. It was concluded that catastrophic failure observed under high collector voltage conditions was probably due to mechanical defects (cracks, lifted metal, etc.) which were propagated in the temperature cycling environment of the life tests.