Materials and Processes in Microwave Integrated Circuits Fabrication

Abstract

Microwave Integrated Circuits (MICs), more precisely Hybrid Microwave Integrated Circuits represent an important and significant step towards the integration and miniaturization of the microwave subsystems and systems when compared to those based on the waveguide/coaxial components. But the level of integration is less than that encountered in the Monolithic Microwave Integrated Circuits (MMICs). In spite of the advent of MMICs, however, MICs continued to assert their place in the microwave systems due to some of their unique features which cannot be fully met otherwise. Also MIC technology adopted itself to the integration of MMICs functional chips in realising the microwave systems. MICs span the range from printed circuit board where the integration is limited to realising the conductor pattern, to the hybrid circuits (thin and thick film) where some or all of the passive components are integrated along with the conductor pattern. Since at microwaves frequencies the circuit dimensions tend to be of the order of the wavelength, every element of the microwave circuit influences its performance (Bhat and Koul 1989 and Van Nie, Goedbloed and Kersuzan 1981). This in turn reflects on the choice of the materials that are used to fabricate the MICs. The quality requirements are more demanding for the materials used for the fabrication of MICs than for the low frequency circuits. In the present chapter efforts are made to highlight various aspects related to some of the materials used for the fabrication of MICs.