ABSTRACT
Metals serve several different functions in the realization of Radio Frequency (RF) and microwave products. These functions include: the wire or guided wave boundary material for circuits and transmission media; the carrier or structural support for dielectric substrates or semiconductor chips; the heat sink for devices or circuits that exhibit high power density, and the reflector element for antennas or screen room applications. Linear expansion properties of metals are important whenever metallic structures are bonded to other materials in an electronic assembly. The best choice of metals to match thermal linear expansion properties is, therefore, determined by the thermal coefficient of linear expansion of the material that is used with the metal. Skin depth can be an important consideration in the development of guided wave and reflecting structures for high frequency work. A poor conductor with a thin layer of high conductivity metal will exhibit the same RF conduction properties as a solid, high conductivity structure.
