The broadest range of materials used in electronics is in components including printed circuit boards, contacts, connectors, switches and relays, grounding contacts, thermal contacts, and integrated circuits. Table 1 lists various electrical components and includes important materials of construction. The corrosion behavior is determined by the actual environment which can be as benign as a simple low humidity, purified atmosphere, indoor location, to the aggressive environment existing at a pulp and paper mill or on an automobile which is subjected to road salt splash and spray. The electronics design as well as the nature of the environment are important because failures in printed circuit boards, integrated circuits, and other components have been known to occur even in extremely low levels of moisture and contaminants. Electronics components are mostly indoor or sheltered from direct exposure to liquid splash, spray, rain, snow, etc., and therefore the environment is considered atmospheric exposure.
Materials used in electronics are susceptible to corrosion in a wide range of environments.
For example, sulfidation of silver in H 2 S occurs in dry as well as humid air. However, moisture in the form of humidity is generally required for atmospheric corrosion to occur. When the humidity is increased, a moisture film can form on the metallic surface and can yield an increased rate of corrosion. However, the humidity at which wetness occurs is dependent on a number of factors including the nature of the material, surface roughness and composition, temperature, and surface contamination including atmospheric pollutants. Since the nature and significance of the moisture film is dependent on very complex and synergistic interactions among a large number of variables, this subject has received a great amount of attention and has resulted in conflicting points of view.