Abstract: A method for early failure recognition in power semiconductor modules which employs a measurement across a resistor between a bonded emitter terminal and a bonded auxiliary emitter terminal that identifies the degradation of the bond point which triggers an early warning signal so that the power semiconductor module can be changed before failure and the overall reliability of an electronic power system can thereby be increased.

Abstract: A method which exploits the phenomenon that an increase of the collector-emitter voltage U.sub.CE of a semiconductor power component during a load change test can be correlated with the service life expectancy of the relevant IGBT module. A method for estimating the service life of a power semiconductor component, comprising the steps of subjecting the component to a periodic load change, measuring an electrical parameter P of the component that serves as an indicator for reliability or durability against the number N of load changes, calculating a derivative dP/dN of the electrical parameter P according to the number N of load changes; and comparing the derivative dP/dN with a target value representing a determined service life. The characteristic "longer-lived than a reference module" or, respectively, "more resistant to failure" can be allocated to a test module if the derivatives of the respective voltage U.sub.CE satisfy the condition (dU.sub.CE /dN).sub.Test <(dU.sub.CE /dN).sub.