Environmental Stress Screening (ESS) Guide

The increasing complexity of mechanical equipment and miniaturization of electronic equipment has made traditional methods of defect detection less efficient. One of the most effective techniques used to identify and eliminate these defects is ESS. ESS is the process of applying environmental stresses, in conjunction with functional testing, in order to stimulate the failure mechanisms of defects to the point of detection. Most of these defects are caused by flawed parts and poor assembly workmanship. The stress levels of applied stimuli must be as harsh as possible to precipitate the defects without causing damage to or reducing the useful life of properly manufactured hardware. Application of environmental stresses will accelerate the latent or undetected defects to become patent detected, with functional testing required to detect failures. Functional testing can be performed either during or after the application of stress. The advantage of functional testing during stress application is that it allows the detection of intermittent failures. This guide provides a step-by-step approach to the planning, implementing, and monitoring of an ESS program for Army Materiel Command Troop Support Command TROSCOM hardware contracts and repair activities. This guide does not replace logical thinking on the part of the user, but presents the various elements of an ESS program and advise the user in their selection and use. Keywords Thermal cycling, Quality assurance, Random vibration.