High quality microwave dielectric ceramic sintered at extreme-low temperature below 200° and co-firing with base metal

Ultra-low temperature co-fired ceramics technology (ULTCC) requires the microwave dielectric ceramics with lower intrinsic sintering temperature than the melting point of inner electrodes. In the present work, a novel HBO2 ceramic was found to be densified at extreme-low temperature below 200 °C, with pores, residual H3BO3, amorphous B2O3 inside, with a relative permittivity ∼2.12 ± 0.02, a Qf value ∼32,700 ± 300 GHz and a temperature coefficient of resonant frequency value ∼ − 43 ± 3 ppm/°C. This material can be easily obtained by dehydration from H3BO3 by sintering at low temperature below 200 °C. Its extreme-low sintering temperature and water solubility also provides the possibility to achieve some novel multi-functional inorganic-organic composite in the future.