A two step procedure to evaluate contact compatibility of organic materials

The formation of carbon on the contact surfaces of commercial relays by thermal decomposition of organic vapors emanating from various organic materials may cause an undesirable increase of the contact resistance in the range of several Ohms. A two stage analysis is proposed, in order to find general rules for the influence of organic materials on contact reliability: The first step of investigation is to determine the molecular structure and quantity of the emanated gases from interesting organic materials by chemical analysis. The second step is to investigate the influence of individual organic vapors and their combinations on contact reliability, using a specially developed test device. The results of preliminary experiments with organic vapors showed that it is possible to determine critical concentrations causing the effect of carbon contamination within a predetermined interval of operations, while lower concentrations did not cause any effect. For organic materials a critical temperature can be determined similarly, as far as a certain temperature of the material corresponds to a certain concentration of emanated gases. Various quantitative informations about contact compatibility of various vapors and materials were gained.