Pi factors revisited

In developing new failure rate models in MIL-HDBK-217E for microcircuits, the need for updated values of three failure-rate adjustment factors (pi-factors) became evident. These pi-factors are the quality factor, the environmental factor, and the learning factor. The logic, methodology, and results of the approach taken in developing these factors are addressed, and a discussion on how to use each pi-factor is provided. The pi-factors discussed are different from those presented in past revisions of MIL-HDBK-217 in that they have been derived from different sets of data from those used to develop the microcircuit models. They are generic to all microcircuits, are flexible and easy to use, and relate to physical attributes (such as device screening) or applicable military specifications