Experimental Investigation of Thermal and Humidity Dynamics in the Enclosures Made of Non-Permeable Walls

The usage of electronics in outdoor environment is growing therefore the control of moisture related failures in electronics are becoming more important. The main cause of these failures is the humidity inside electronics which may condense on the surfaces or components. To protect electronics from harsh environment, the components and electronics are encapsulated by using electronics enclosures, however it does not prevent from moisture ingress through plastic walls, gaskets, cable feedthroughs and etc. Thus, to control the humidity, it is very important to understand the humidity ingress and behaviour in the electronics enclosures. Hence, the paper concerns the study of temperature and moisture dynamics when electronics enclosure is exposed to a cyclic temperature condition according to MIL-STD-810F. Two different enclosures were selected for the experiment, namely, aluminum enclosure and glass jar. The study was carried out in a climatic chamber and the measurements of temperature and relative humidity were performed using sensors. Different effect of enclosure material was considered for humidity ingress. In aluminum enclosure, results showed that the temperature difference between different points are smaller than in case of glass jar. Different temperatures in enclosures are determined by different boundary conditions outside the enclosure caused by the climatic chamber.