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Engineering LibreTexts

1.3: Electronic Materials and Products

Progress in Electrical Engineering was always dependent on progress in materials. For quite some time, electrical engineering meant electromechanicalengineering, and electrical products were made from "trivial" materials, as seen from a modern point of view. What was needed were cables, insulators, ferromagnetic sheet metal for transformers and generators, and a lot of metal for the general mechanics. A few applications centered around some mysterious materials - out of that grew electronics and electronic materials. But even then there were key materials:

  • Cu wires of all kinds. Not so trivial - how do you make a insulated but still flexible wire?
  • Insulating materials - plastics didn't quite exist yet. Mica was one of the key materials - there were mines for it!
  • Graphite and tungsten were important, whenever things got hot, like the filament in the light bulb or in a vacuum tube.
  • The "tube of Braun" - the "Braunsche Röhre" as it was known in Europe - the first cathode ray tube (CRT) in other words - needed complicated glass work and some ZnS as electroluminescent material
  • Strange compounds like "phosphor bronze" were developed for contacts.
  • And Selenium (Se) was important for rectifiers, although nobody quite understood how it worked.

The essential break through in the thirties was the vacuum tube; with it came electronics: Rectifiers, amplifiers, radio, black-and white TV, colour TV. It's not that long ago, but obviously long enough for some not to remember! The next break-through was called transistor; it happened in 1947. Integrated circuits followed around 1970, and since then we witness exponential growth with growth rates in the complexity of electronics (at constant prices) of up to 40% a year! A good (german) book covering this development in some detail is Hans Queissers "Kristallne Krisen".