Low permittivity MgO–xB2O3–yBaCu(B2O5) microwave dielectric ceramics for low temperature co-fired ceramics technology

Abstract

MgO–xB2O3–yBaCu(B2O5) ceramics were prepared by a solid-state reaction method. The phase composition and microwave dielectric properties of ceramics were studied. The MgO-rich ceramics (x = 1/4, 1/3 and 1/2) contain MgO and Mg3B2O6. But the B2O3-rich ceramics (x = 1, 2 and 3) contain B2O3, MgB2O4 and Mg2B2O5. The MgO–xB2O3 (x = 1/4, 1/3, 1/2, 1, 2 and 3) ceramics show high Q × f of 41,754–105,852 GHz, low er of 4.24 ~ 7.68 and negative τf values of − 56 to − 30 ppm °C−1 with tuning the x values. The BaCu(B2O5) (BCB) was used to reduce the sintering temperature of MgO–2B2O3 ceramic. The MgO–2B2O3-4 wt% BCB ceramic sintered at 925 °C exhibits good microwave dielectric properties with high Q × f of 30,589 GHz, low er of 4.8 and negative τf value of − 40 ppm °C−1. Importantly, MgO–2B2O3-4 wt% BCB ceramic has a good chemical compatibility with Ag, which illustrates that it is a candidate material for low temperature co-fired ceramic devices.