Measurement of complex permittivity of low temperature co-fired ceramic at cryogenic temperatures

Abstract

Precise knowledge of microwave properties of Low Temperature Co-fired Ceramic LTCC materials is crucial for efficient design of microwave systems, especially for design of communication filters. Many communication devices operate at low temperatures. In order to implement LTCC at low temperature communication circuits and devices, Engineers need precise values of the complex permittivity. The aim of this paper is to characterise LTCC material as a function of temperature at microwave frequencies using a very precise measurement technique, Split Post Dielectric Resonator. The Transmission Mode Q-factor technique that eliminates all the parasitic losses during the characterisation was used for the S-parameter data processing. The permittivity and loss tangent data of LTCC manufactured by Heraeus Circuit Materials Division in the temperature range 20 K- 300K at a frequency of 9.5 GHz is reported in this paper. The random uncertainty in εT and tanδ are better than 0.3% and 5 % respectively.