An infant mortality and long-term failure rate model for electronic equipment

This paper describes the reliability model used by system designers at AT&T Bell Laboratories to predict component and equipment reliability. A decreasing-failure-rate Weibull model describes the high incidence of early-life failures, or infant mortality. This is combined with the constant-failure-rate (exponential) model traditionally and widely used for the long term. Formal modeling of both early-life and long-term reliability is needed to manage the development and manufacture of reliable products. The effects of temperature and electrical stress on failure rate are taken into account. A model for the effect of integrated circuit dynamic burn-in on reliability is also described.