Degradation of Contacts and Package Interconnections

The unifying theme of this chapter encompasses problems that arise in maintaining electrical continuity between conductors. We have all instinctively diagnosed poor contacts as the source of malfunction in some piece of electrical equipment or other, and often been correct. In the days before transistors, the simple act of making a local telephone call activated hundreds of electro-mechanical contacts, whose inefficient operation or malfunction meant signal distortion, noise, or even lack of signal transmission. Whether they are “static,” as in permanent soldered interconnections, or are “dynamic,” sliding and rotating, as in switches and motors, electrical contacts pose a variety of interesting and important reliability problems.