The superior electro-thermal properties of silicon carbide (SiC) power devices permit higher temperature of operation and enable higher power density compared with silicon devices. Nevertheless, the reliability of SiC power modules has been identified as a major area of uncertainty in applications which require high reliability. Traditional power module packaging methods developed for silicon chips have been adopted for SiC and the different thermomechanical properties cause different fatigue stresses on the solder layer of the chip. In this paper, a 2-D finite element model has been developed to evaluate the stress performance and lifetime of the solder layer for Si devices, which has been validated using accelerated power cycling tests on Si IGBTs. The proposed model was extrapolated for SiC devices of the same voltage and current rating using the same solder material and the results show that under the same cyclic power loss profile the induced stress and strain energy in the die attach layer is much higher and concentrates on the die/solder interfacial area for SiC chips. Using the validated stress-based model, the lifetime can be quantified when SiC chips are used. This ability to extrapolate the available power cycling and lifetime data of silicon chips to SiC chips would be a key element for developing reliable packaging methods for SiC devices.

Power electronics are efficient for conversion and conditioning of the electrical energy through a wide range of applications. Proper life consumption estimation methods applied for power electronics that can operate in real time under in-service mission profile conditions will not only provide an effective assessment of the products life expectancy but they can also deliver reliability design information. This is important to aid in manufacturing and thus helps in reducing costs and maximizing through-life availability. In this paper, a mission profile-based approach for real-time life consumption estimation which can be used for reliability design of power electronics is presented. The paper presents the use of electrothermal models coupled with physics-of-failure analysis by means of real-time counting algorithm to provide accurate life consumption estimations for power modules operating under in-service conditions. These models, when driven by the actual mission profiles, can be utilized to provide advanced warning of failures and thus deliver information that can be useful to meet particular application requirements for reliability at the design stage. To implement this approach, an example of two case studies using mission profiles of a metro-system and wind-turbines applications is presented.