Effects of manufacturing defects on the device failure rate

This study investigates the effect of manufacturing defects on the failure rate for a population of repairable devices and for a population of non-repairable devices. A reliability function is obtained for a random number of manufacturing defects in a device following a general distribution. We observe that for any population, the failure rate decreases if the device-to-device variability of the number of defects is large enough. Considering a case further where the defect size initially follows a linear-power-law distribution and increases at a rate that is proportional to the defect size at any instant during field operation, we show that the defect growth and defect clustering plays an important role in inducing the decreasing property in the failure rate function.