Aerospace electronics reliability: Could it be predicted in a cost-effective fashion?

We present a method for predicting the failure rate, and thus the reliability of an electronic system by summing the failure rate of each known failure mechanism. We use a competing acceleration factor methodology by combining the physics of failure for each mechanism with their effects as observed by High/Low temperature and High/Low voltage stresses. Our method assumes that lifetime of each of its failure mechanisms follows constant rate distribution and each mechanism is independently accelerated by the stress factors, which include also frequency, current, and other factors that can be entered into a reliability model. The overall failure rate is thus, also follows an exponential distribution and is described in the standard FIT (Failure unIT or Failure in Time). The method combines mathematical models for known failure mechanism and solves them simultaneously at a multiplicity of accelerated life tests to find a consistent set of weighting factors for each mechanism. The result of solving the system of equations is a more accurate and a unique combination for each system model by proportional summation of each of the contributing failure mechanisms.