Design Trends in Tomorrow's Capacitors

A realistic appraisal is made of present capacitordesign improvements, and of immediately-forseeable design trends. Three trends are discussed--those toward reliability, low voltage, and automation. In the area of reliability, accelerated-life and vibration test results are presented, covering 8950 "Hyrel Q" impregnated-paper capacitors. It is pointed out that as the demand for such capacitors increases, the cost differential relative to the garden-variety of sub-miniatures will become very small. It is emphasized that highreliability tantalum-electrolytic, metallized-paper, and ceramic capacitors will be available in the near future and that the developed processes will "rub off" on other types. The low-voltage trend is discussed in its relation to solidtantalum and other electrolytic types. The new Sprague 109D liquid-electrolyte porous-anode tantalum capacitor is described, and a 2- or 3-to-1 volume-efficiency advantage is shown over previous low-voltage types. Other performance, environmental, and reliability advantages are cited. Improved metallized-paper capacitors are placed in a new niche of reliability; and complex-film types are announced for replacing mica and ceramic types. Life-test data is presented showing a 44-to-1 improvement for one dielectric-film combination. The automation trend is pictured as toward the molded-paper capacitor, because of its better handling and tolerance qualities. Presently-available more-common types are listed, and some pending improvements are mentioned. Two molded automation types are described. A new monolythic multi-layer ceramic capacitor is announced which has approximately 70-times the capacity of previous ceramics using 20-mil disks. It is emphasized that the surface has only been · scratched in the development of new materials for capacitors. In conclusion, it is pointed out that greater standardization on the part of the electronics industry toward a reduction of' types and in stopping the usage of obsolete types will result in better capacitors, and at lower prices.