ABSTRACT
From the beginnings of the electrical industry, critical circuit components have been coated, buried, or otherwise encased in dielectric materials to isolate them from adverse environmental and operational effects of oxygen, moisture, temperature, electrical flashover, current leakage, salt spray, radiation, solvents, chemicals, microorganisms, mechanical shock, and vibration. The first materials used for this purpose were waxes and asphaltic compounds. Although these substances are still used to some extent, synthetic polymers are now the most widely used electrical encapsulants. The advantages of potting and encapsulating and coating electronic components were realized several decades ago, but the limited choice of materials available before World War II, mainly bituminous compounds and waxes, restricted the used of these processes on a broad scale. During World War II, the design of the proximity fuze sparked the development of high performance potting compounds based on dichlorostyrene. Today’s materials have indeed come a long way.
