Failure Mechanisms of Electromechanical Relays on PCBAs: Part II

This is the second article in a two-part series on the causes of failure in electromechanical relays. Part I, in the February 2018 issue of EDFA, examines a variety of failures caused by the formation of oxide on contact surfaces. As the author explains, electric arcing in the presence of silicon oil or vapor creates SiO₂ deposits in the contact region that build up over time. Here in Part II, the author presents examples of failures caused by nitrous gases, phosphoric acid crystals, and wax, which is often found on enameled copper wires.