Abstract: The properties of different kinds of polyurethane-typed conformal coating products were studied. The basic performances, they were at the same level, such as the similar flame retardancy and electrical insulation under normal conditions, so it is unable to determine the best applicable situation. Thus, a series of environmental experiments were carried out, such as neutral salt spray test, thermal shock test and constant temperature and humidity test. During the environmental test, the electrical performance and change in appearance of different periods were recorded and analyzed. Through the analysis of the comprehensive performances of the products, the best applicable environments and regions are optimally selected.

Key words: Polyurethane resin, Conformal coating, Weather resistance, Yellowing