Temperature-stable Ba0.8Sr0.2CuSi2O6 microwave dielectric ceramics for LTCC application achieved with the addition of LBSCA and LBBS glass

Abstract

Ba0.8Sr0.2CuSi2O6 ceramics have a low dielectric constant, which is useful for low-latency 5G communication. To enable the preparation of Ba0.8Sr0.2CuSi2O6 low-temperature co-fired ceramic (LTCC) materials, LBSCA and LBBS were used in this paper to reduce the sintering temperature of Ba0.8Sr0.2CuSi2O6. The effects of LBSCA and LBBS on the phase composition, densification, microscopic morphology, and vibrational characteristics of the ceramics were investigated by X-ray diffraction, scanning electron microscopy, density measurements, and Raman spectroscopy, and the causal factors influencing the microwave dielectric properties with the addition of glass were analyzed. It was found that 0.4 wt% LBSCA glass and 1 wt% LBBS glass reduced the sintering temperature to 925 °C, and these prepared ceramics had excellent microwave dielectric properties. The ceramic prepared with 0.4 wt% LBSCA glass had an εr value of 7.672, Q × f value of 37193 GHz, and τf value of −14.93 ppm/°C, while the ceramic prepared with 1 wt% LBBS glass had an εr value of 7.512, Q × f value of 32136 GHz, and τf value of −13.92 ppm/°C. The phase composition of the ceramics did not significantly change, indicating that neither glass reacted with the ceramics. The εr value was affected by both density and Raman shift, the trend in the Q × f values was consistent with the density, and the τf value decreased with increasing glass content, which was attributed to the liquid phase generated by the glass in the ceramic. In addition, co-firing these glass-doped ceramics with Ag at a low temperature resulted in good chemical compatibility. Combined with the near-zero τf, these results demonstrate the excellent promise of these two ceramics as alternative materials for LTCC microwave devices and their application in 5G communication.