Dielectric Materials and Capacitor Miniaturization

Capacitor improvements over the years have been largely identified with progress in dielectric materials. In this paper, emphasis is placed on miniaturization, especially as it relates to capacitor dielectrics. Modern capacitors can be divided into two general types: bulk capacitor types, most often used as discrete elements; and film capacitor types, which to date are exclusively single-layered and most useful in integrated thin-film networks. In bulk capacitor types, one strives for minimum volume, and the major volume factor is often the dielectric itself. A dielectric volume efficiency factor can be defined as eS2, where e is the dielectric constant and S is the permissible working stress. In some instances, as in electrolytic capacitors, electrode volume can also be appreciable. For film capacitor types, the area must be minimized and an area efficiency factor equal to eS is important. Consideration is given to contamination control, packaging, and novel structures.