Much of the progress towards ever greater miniaturisation made by the electronics industry, from the early days of valves to the development of the transistor and later the integrated circuit, has only been made possible because of the availability of various polymeric materials. Indeed, many new plastics have been developed specifically for electri­ cal and electronic device applications and as a consequence the plastics and electronics industries have continued to grow side-by-side. Electronic components are one of the few groups of products in which the real cost performance function has declined significantly over the years, and part of the reason can be directly attributed to the availability and performance of new polymeric materials. The evolu­ tion of the personal computer is a specific example, where improve­ ments in polymer-based photoresists and plastic encapsulation techni­ ques have allowed the mass production of high-density memories and microprocessors at a cost which yields machines more powerful than mainframe computers of 30 years ago for little more than the price of a toy. Today, plastic materials are widely used throughout all areas of electrical and electronic device production in diverse applications ranging from alpha particle barriers on memory devices to insulator mouldings for the largest bushings and transformers. Plastics, or more correctly polymers, find use as packaging materials for individual microcircuits, protective coatings, wire and cable insulators, printed circuit board components, die attach adhesives, equipment casings and a host of other applications.