Detailed Characterization of Indigenous Alumina Substrates for Thin & Thick Film Hybrid Microcircuits

Abstract

Alumina substrates are widely used for the realization of Thick and thin film circuits for Aerospace applications. Ceramic Substrates are preferred for critical applications due to lower losses, repeatable performance and high reliability for Digital, Power and RF applications. Ceramic substrate properties such as alumina elements composition, dielectric constant, camber, surface finish are of utmost importance as variations in parameters can compromise circuit performance and variations in the measured results at extreme temperatures. In system level overall variations with temperatures can result in much degraded system performance rendering it not useful for high end applications. Thick and Thin film circuit substrates are having varied purity levels whereas dielectric loss is an important parameter for thin film substrate at higher frequencies. This article details the characterization of thin and thick film substrates for hybrid microelectronics applications, various parameter and detailed analysis which is performed on two types of substrates with different purity levels. Further transmission line and band pass filter are fabricated for thin film applications at RF frequencies, analysis of circuit performance at microwave carried out and role of purity level along with effect of temperature excursion are analysed and presented. The present study will facilitate totally indigenous ceramic substrate development for aerospace applications and pave way for self-sufficiency.