The Evolution of Organic Vapors from Plastic Materials Associated with Electromechanical Relays

Plastic materials used in the construction of relays and in associated equipment units evolve organic vapors; the evolutions can give rise to insulating organic films on catalytically active contact materials such as platinum group metals. A variety of experimental methods have been used to determine the extent and (in some cases) identity of these vapors; these methods are criticized and a standard procedure is outlined and applied in the comparison of over twenty classes of plastic material. Even the best materials can represent some hazard to platinum group metal contacts, so that a careful selection of plastic materials is necessary together with other steps to improve relay reliability.