Protective coatings of electronics under harsh thermal shock

Industrial electronics devices commonly encounter harsh environmental conditions during their operational lifetime. To protect the electronics from conditions like humidity and contaminants, protective moulding and coating materials can be used. However, the behaviour of materials in harsh environments and their effect on the reliability of electronics in industrial products has been studied only very little. Moreover, the changes in the parameters of several commonly used materials under various conditions remain largely unknown. In this paper the effect of the protective coating and moulding materials on product level reliability of an electronics device was studied under thermal shock test. In addition, the change in the mechanical properties of the materials under test conditions was studied. The conditions of the test used were relatively harsh with extreme temperatures of −40 °C and +125 °C. The samples used in the study were commercial electronics devices designed for use in harsh conditions. The protective materials studied included silicone based conformal coating, polyurethane based moulding material, and silicone based moulding material. Moreover, a comparison test with no protective materials was conducted. The results showed that conformal coating and polyurethane based moulding material markedly decreased the times to failures of the devices. On the other hand, silicone based moulding seemed to slightly improve the reliability of the devices.