Climate & Environment | Temperature and Humidity Test (Damp Heat Test)

In any natural environment, temperature and humidity are essential environmental conditions and change variable according to geographical locations. For example, Taiwan is a typical island climate with year-long high humidity, but continental climates face drastic day-and-night temperature changes. 

According to IEC60721, there are four conditions in the atmosphere: High Temp./Low Humidity, High Temp./High Humidity, Low Temp./High Humidity, and Low Temp./Low Humidity. In IEC60721 and ETSI 300 019, European Telecommunications Standards, there is a clear chart on recommended temperature and humidity. To prevent confusion and obscurity of failure root cause, most worldwide companies will conduct dry heat test, cold test, constant temperature/ humidity test, humidity cycle test separately. 

For plastic, PCB, PCBA multi-hole materials or products, each material will have a different effect by temperature and humidity. Temperature effects are usually caused plastic deformation, product overheat, poor cold start, etc. For multi-hole material and products, the breathing effect in a humid environment will cause surface moisture absorption, permeation, and condensation; while a low temperature environment, accumulation of ESD will cause failure easily. Therefore, different temperature and humidity might cause the different failure phenomenon. From the lots of experiment, temperature and humidity tests can find out lots of potential defects for product or material, such as PCB or PCB Assembly Dendrite Effect after raw material or process changes. Popular phenomenon caused by humidity effects include physical strength deduction, chemical migration, deterioration of insulation, short circuit, oxide on metal surface, loss of flexibility, component pop-corn effect, etc.

Condensation is one of important stress for not only outdoor(exposure in the atmosphere product), but also indoor product, due to condensation on product will easily cause the shorts and fail. For the key component of automotive application, condensation test is requested by OEM(vehicle company) as well.