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With the combined increase in miniaturization of electronic systems and the explosive increase in their availability, it is expected that the corrosion and deterioration of electronics will become a societal issue with dire unpredictable consequences. Corrosion mechanisms in electronic components have been the subject of extensive studies. Since electronics are largely found indoors or within enclosures, the mechanisms leading to corrosion problems are not easily defined. Problems are compounded by the fact that these systems are fabricated by a number of complex processes and consist of a variety of dissimilar materials. Miniaturization and the requirement for high component density has resulted in smaller components, closer spacing, and thinner metallic paths. Thus, the effect of bias potentials and small defects is magnified.
| Corrosion in electronic components manifests itself in several
ways. Computers, integrated circuits, and microchips are now an integral
part of all technology-intensive industry products, ranging from aerospace
and automotive to medical equipment and consumer products, and are therefore
exposed to a variety of environmental conditions. Corrosion in electronic
components are insidious and can not be readily detected. Therefore, when
corrosion failure occurs, it is often dismissed as just a failure and the
part or component is replaced. Because of the difficulty to detect and identify
corrosion failures, the cost of corrosion is difficult to determine. (reference) According to the US Census Bureau, the American electronic manufacturing industries alone shipped 336 billion dollars worth of electronic components in 1997. As electronic devices become increasingly ubiquitous and robust, the concern over the operating environment seems to lessen, particularly in the personal computer (PC) market. The trend toward miniaturization of technology has led to the development of small personal electronic devices that are now present everywhere, such as pagers, cellular phones, and palm-sized personal organizers and computers. (reference) Materials used in electronic components range from aluminum-based alloys (integrated circuits conductors) to copper contacts electroplated with nickel or gold for improved resistance. Submicron dimensions of electronic circuits, high-voltage gradients, and an extremely high sensitivity to corrosion or corrosion products present a unique set of corrosion-related issues. A major departure from most corrosion situations is the incredibly small volume of the material that can be damaged and lead to a fault. The microchip in an automobile, for example, is not directly subjected to the same environmental hazards as the car body. However, the tolerance for corrosion loss in electronic devices is many orders of magnitude less, i.e. on the order of picograms (10-12 g). Minimum line width in the state-of-the-art printed circuit boards (PCBs) in 1997 was less than 100 mm. On hybrid integrated circuits (HICs), line spacings may be less than 5 mm. (reference) |
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