IEC 60749-24 Ed. 1.0 b:2004

The unbiased highly accelerated stress test is performed for the purpose of evaluating the reliability of non-hermetically packaged solid-state devices in humid environments. It employs temperature and humidity under non-condensing conditions to accelerate the penetration of moisture through the external protective material or along the interface between the external protective material and the metallic conductors which pass through it.