Establishing effective ORT requirements

In some cases the use of reliability testing to sample the products at the end of assembly provides an effective means to detect shifts in materials and processes that adversely impact product reliability. Ongoing Reliability Test (ORT) design is a balance considering cost, timeliness, resolution, and accuracy. A poor ORT is costly and may increase the risk of significant field failure by falsely building management confidence. Or, the testing may be unable to detect even major adverse changes in the field failure rates by not evaluating the appropriate risks or with insufficient sampling. This paper steps through the design of an effective product ORT program for a high volume consumer product. The analysis includes business objectives, design risk, vendor variability, and accelerated life testing considerations, while also considering the real factory constraints concerning equipment, skill, and time. Considering the constraints and the major decisions based on the testing results permits the ORT to become an effective part of process control while providing protection from un wanted field failures. An effective ORT evaluates sufficient number of samples, with a set of stresses that accelerate the appropriate failure mechanisms and produces test results in a timely and informative manner.