Microwave semiconductor device-insulation trends and requirements

In the electronics industry, outside of the electron tube field, there is a class of devices that make important and significant use of insulating materials. These devices are of the semiconductor class such as transistors, diodes and integrated circuits. Generally, the insulating material is important, primarily for its basic mechanical properties, since it is used as a packaging medium. In more recent years, of course, thermal properties, sealing properties, etc., have come to be important. There is one class of diode, however, now closely being followed up by certain transistors and even integrated circuitry that has been significantly dependent upon the electrical properties of the insulating material. The microwave diode is probably the only device over the past fifteen to twenty years that has been so dependent (with the exception of high voltage breakdown criteria). Mostly being very low voltage devices (up to 6V) for many years, some diodes are now built with 1000V capabilities. We have been mainly concerned with dielectric constant and loss tangent as the important insulating electrical properties. The frequency spectrum of consideration is from 1000 MHz to at least 100,000 MHz. While this paper is mainly concerned with microwave diodes, it touches briefly on a new concept: the integrated microwave circuit.