Mean Time Between Failures (MTBF)

This chapter discusses mean time between failures (MTBF), which is the measure of equipment reliability. It presents an equation that can be used to derive the probability that a piece of equipment will experience no failures in a particular given time. There are several methods of calculating MTBF for a piece of equipment. The most common is based on the failure rate of each component, the number of components, and the environmental stresses on the components. Based on each individual component, it is possible to derive the overall steady-state failure rate by summing the failure rate for each component part and applying a unit environmental factor. Excel initiates a workbook with three worksheets. The first step in building the Excel model is entering a bill of material into Excel. The chapter describes five fields required for each part in the bill of materials: the device failure rate, the temperature stress curve, the electrical stress curve, the device quality factor, and the maximum electrical stress permitted for the device.