Room-temperature densified Al2O3-H3BO3 ceramics with excellent microwave dielectric properties and thermal conductivity for chip packaging

As electronic devices become increasingly miniaturized and demand greater integration, traditional packaging technologies face substantial challenges in meeting the needs for high-frequency performance and system reliability. Ceramic materials, known for their excellent dielectric properties and thermal stability, are promising candidates for advanced packaging applications. However, conventional high-temperature densification processes, which often exceed 1000 °C, restrict their compatibility with temperature-sensitive components in modern electronic systems. To overcome this limitation, we propose a novel approach to densify Al 2 O 3 -H 3 BO 3 ceramic at room temperature under low uniaxial stress. It is found that a H 3 BO 3 facilitates plastic deformation in the medium of deionized water, enhancing the densification of Al 2 O 3 -H 3 BO 3 ceramics even at minimal uniaxial stress. The resulting material exhibits a high relative density of over 96% and possesses excellent microwave dielectric properties (relative permittivity : 2.84–5.37; values: 12,924–69,000 GHz; resonant frequency values: −156.94 10 –6 ·°C –1 to −73.42 10 –6 ·°C –1 ) and thermal conductivity ( values: 1.96–5.96 W·m –1 ·K –1 ). After co-firing with a silicon wafer, the ceramic maintains its structural integrity, with no observable atomic diffusion at the ceramic-silicon interface, rendering it a potential candidate for advanced packaging and integration technologies. • Room-temperature densified Al 2 O 3 -H 3 BO 3 ceramics by cold sintering process. • Obtained ceramics exhibit excellent microwave dielectric properties and a high thermal conductivity of 5.96 W·m –1 ·K –1 . • Ceramic and silicon wafer are co-fired.