Temperature Coefficient of Microwave Resonance Frequency of a Low‐Temperature Cofired Ceramic (LTCC) System

Abstract

A family of low‐temperature cofired ceramics (LTCC) based on mixtures of a commercial dielectric, MgTiO 3 –CaTiO 3 (designated MMT‐20) and ZnO, SiO 2 , and B 2 O 3 , has been investigated for microwave applications. The main objective was to optimize the three key properties—relative permittivity (ɛ r ), dissipation factor (DF), and the temperature dependence of the microwave resonance frequency (τ f )—through adjustment of the composition. A further objective was to estimate the limits on compositional variability while maintaining acceptable properties. The developed microstructures, after firing at 900°C, were studied using X‐ray diffractometry and scanning electron microscopy/energy dispersive spectrometry techniques and compared with the dielectric parameters. The optimum composition (wt%) was found to lie in the ranges 45.8–44.9, ZnO; 17.25–17.55, B 2 O 3 ; 6.95–7.05, SiO 2 ; and 30–30.5, MMT‐20, yielding values of ɛ r = 8.5–9.5, DF < 0.93 × 10 −3 ppm/K, and τ f < ±10 ppm/K.