In the twilight zone of humidity testing

摘要

After working for over 25 years in the field of reliability, product test, and validation I am still a bit mystified by humidity testing, especially where it applies to the reliability of electronics designed to operate in harsh environments (automotive, defense, avionics, etc.). Generally speaking, from a reliability standpoint environmental tests can be loosely divided into two categories: 1. Durability tests, which are designed to exercise some form of wear-out failure mechanism, such as high- or low-cycle fatigue, electro-migration, corrosion, creep, and so forth. The most common examples of durability tests include vibration and thermal cycling, where the number of temperature cycles or duration of vibration at a certain G-level are correlated with the field exposure via some form of acceleration factors or acceleration model. 2. Capability tests, sometimes referred as overstress tests, with the goal of determining how well the product can survive under certain applications or environmental conditions such as dust, high voltage, drop, salt spray, and some others.