The purpose of this project is to investigate microcircuit reliability in the temperature range of -55 deg c to 125 deg , identify temperature dependence of all microcircuit failure mechanisms, identify existing models, identify gaps in the existing models and, wherever the data exists, formulate new models where there are none. This will lay the foundation for the phase U project which will refine and validate the models proposed in phase U. The key factor is to determine the temperature dependence of microcircuit failure mechanisms. This requires the investigation of the various physics of failure mechanisms and modes of failure for microelectronic devices. The final report will include the temperature dependent equations which govern electronic equipment failures. These equations may be functions of absolute temperature, the temperature change magnitude, rate of temperature change, temperature history, or spatial temperature gradients. We will not back-out temperature dependencies from mil-hdbks or industry handbooks in which the actual cause of failure was not appropriately identified. A discussion of temperature dependent failure mechanisms for microelectronic devices forms the body of this proposal.