Quantitative models for second breakdown in transistors

Two models are discussed which can be used to predict both forward and reverse second breakdown limits. The thermal model, which applies to forward second breakdown, includes the effects of base and emitter ballasting. The electrical model is most applicable to the case of reverse second breakdown and is based on the mechanism of avalanche injection. Good agreement between the predictions of the models and experimental measurements is demonstrated. Emphasis is placed on those results which are likely to be of importance to the device user.