Improving the sintering performance and dielectric properties of thermally conductive low-temperature co-fired alumina by controlling the firing atmosphere

Abstract

Here, we focused on the firing atmosphere to promote low-temperature sintering and enhance the dielectric properties of low-temperature co-fired alumina (LTCA) containing 5 wt.% of CuO–TiO2–Nb2O5–Ag2O as the sintering aid. Controlling the oxygen partial pressure (pO2) to form Ag–Cu–Ti–Nb–O-based complex oxides and lowering the melting temperature of the sintering aid are necessary to improve the sinterability. Moreover, controlling the pO2 such that AgNbO3 disappears is important to improve the dielectric properties of LTCA. A dense sintered body with approximately 95% relative density was obtained by firing an LTCA sample for 2 h at a firing temperature of 900°C and pO2 of 0.02 atm, and its dielectric properties were measurable. The thermal conductivity of 17 W/mK was better than that of conventional low-temperature co-fired ceramics (2–7 W/mK). These results provide important guidelines for low-temperature sintering and producing LTCA with enhanced dielectric properties.

Keywords

• low-temperature co-fired alumina (LTCA)
• firing atmosphere
• Ag–Cu–Ti–Nb–O-based complex oxide
• microwave dielectric property
• high thermal conductivity