Chapter 4.3 - Qualification Testing

Abstract

This chapter describes the methodology generally adopted for qualification testing of products and components with respect to environmental resistance. For assessing the durability of a product, component, or material, it is important to distinguish between (a) the resistance to the short term influence of exposure to environmental stresses representing cases of high environmental loads on the component and its materials, and (b) the resistance to the long-term influence of exposure to environmental stresses that may result in the gradual degradation of the materials. For characterization and specification of the severities of stresses in the first case, the standard lEC 60721 may be used as a starting point. In this standard the severity for environmental factors in different applications is given as the maximum value to which the product may be exposed. lEC has also published a standard on basic environmental testing procedures, lEC 60068-2, which only treats test methods. The environmental resistance of a product may be verified by using a number of available standard environmental resistance tests related to the action of mechanical, climatic, chemical, and biological environmental stress factors. Some of the tests can be applied directly for qualification of products. However, in the case of long-term influence to environmental stresses and gradual degradation of the materials, appropriate accelerated life tests have to be tailor-made for qualification testing and correspond to the expected in-service environmental conditions, but at enhanced stress levels.