Enhanced thermal conductivity and flexural strength of Si3N4 ceramics by using YF3-MgSiN2 as sintering additives

Si 3 N 4 ceramics stand out as ideal materials for advanced electronic packaging substrates due to their high mechanical strength, high-temperature resilience, and minimal dielectric constant. Optimizing both the mechanical and thermal conductivity is essential for ensuring their reliable performance. In this study, a systematic investigation into the impact of both oxygen-containing sintering additives (Y 2 O 3 -MgF 2 and Y 2 O 3 -MgSiN 2 ) and oxygen-free sintering additives (YF 3 -MgF 2 and YF 3 -MgSiN 2 ) on the microstructure, flexural strength, and thermal conductivity of Si 3 N 4 ceramics has been performed. It demonstrates that the Si 3 N 4 ceramic sintered with the YF 3 -MgSiN 2 additive achieves a remarkable thermal conductivity of 111.63 W·m −1 ·K −1 and a flexural strength of 774.7 MPa, which is relatively rare among the reported Si 3 N 4 ceramics. These exceptional properties are attributed to the use of YF 3 -MgSiN 2 additive, which leads to a significant reduction in lattice oxygen content, along with a decrease in the liquid phase formation temperature, thereby promoting grain development. Furthermore, the decomposition of MgSiN 2 at high temperatures plays a key role in purifying the grain boundaries. This study provides a promising approach for developing high-performance Si 3 N 4 ceramics with excellent thermal conductivity and mechanical strength.