Coating, painting or potting

For some applications, printed circuit boards must be painted or encapsulated. Only relays with protection class RT III should be used for this purpose. We recommend one-component lacquers based on epoxy or polyurethane resins applied by spraying. Silicones or materials containing silicone must not be used. Special suitability tests of the paint must be carried out. Due to capillary action, the lacquers can creep between the relay and the PCB. During the subsequent drying or curing process, they may not cure completely there. Lacquer vapours may then penetrate into the interior of the relay and impair its functionality. If the PCB is encapsulated with the relays, heat dissipation may be altered by the encapsulation. The user must carry out additional tests to check whether the performance data of the relays may have to be reduced.