Detection techniques for non-destructive second-breakdown testing

This paper describes the development of non-destructive second-breakdown measuring techniques and equipment. Such apparatus is vital for analysis of the "safe area of operation" of transistors for device development and particular circuit application. The new technique is useful for detecting second breakdown in both the forward-biased and the reverse-biased mode. When a transistor is operated in the forward-biased mode, hot spots may develop which produce second breakdown if temperature extremes are reached. With existing detection methods, the device may already have been damaged before this condition is recognized. A technique for electronic detection of hot spots before such degradation occurs is illustrated and compared to phosphorus ultraviolet and infrared scanning techniques. When this new technique is used, transistors can be characterized for forward-biased "safe area of operation" for applications such as audio output stages, series regulators, and class AB linear rf power amplifiers.