Burn-in is an effective method to screen out early failures of electronic devices. Typically, this is achieved by operating the devices under accelerated stress conditions. This paper focuses on a burn-in concept where a random sample of devices is drawn out of the running production, put to burn-in, and investigated for early failures. This procedure is called burn-in study. In parallel, as long as the burn-in study is ongoing, all other produced devices are subjected to burn-in screening. In this article, new flexible sampling plans for burn-in studies are introduced. These are based on the progress of these studies and defined quality targets. Furthermore, these sampling plans enable fast burn-in time reductions and various time reduction strategies. From a statistical point of view, this requires to combine the proportion of early failures in a population with their lifetime distribution function. The new model is illustrated by case studies and simulations. It contributes to burn-in cost reductions, while controlling quality levels at the same time.
K E Y W O R D Sbinomial distribution, burn-in, consumer's risk, lifetime distribution, sampling plan, zero defects
INTRODUCTIONElectronic devices typically have an increased failure rate at the beginning of their lifetime which decreases over time. This phase is called early life. The burn-in (BI) is a state-of-the-art technique to screen out early failures of electronic devices. BI simulates the early life of the products under stress conditions for a certain time; this is the BI time. In doing so, early failures can be detected prior to delivery. Instructive overviews about BI are provided by Block and Savits, 1 Kececioglu and Sun, 2 and Kuo et al. 3
BI concepts for semiconductor devicesIn quality management, there are two major strategies to control quality levels:• 100% control and • random sampling.