2.1 Introduction

Prior to 1930, most household goods and industrial components were made of metals, wood, glass, paper, leather, or vulcanized rubber. Since then, plastics have made significant advances in the markets of all these materials as well as creating new markets of their own. The widespread use of plastics has been brought about because of their unique combination of properties such as strength, light weight, low cost, and ease of processing and fabrication. Plastics are not the panacea of industry s material problems, but they offer such a unique combination of properties that they have become one of the important classes of materials and have found widespread use in the electrical and electronics industries.

Plastics play a key role in these industries and function in a variety of ways. The most common application of polymers in electrical and electronic devices is for insulation, which prevents the loss of the signal currents and confines them to the desired paths. Insulation systems exist in a variety of forms (liquids, solids, and gases), and the type of material used determines the life span of the device. Plastic materials also perform structural roles, support the circuit physically, and provide environmental protection from such elements as moisture, heat, and radiation to sensitive electronic devices. Continuing improvements in the properties of plastics over the years have made them even more important to the electrical industry by extending their useful range.

It is the purpose of this chapter to...