Sintering behavior, microstructure, and properties of CaO–B2O3–SiO2/β–Si3N4 composites for LTCC application

The advancement of high-density integration and packaging technologies necessitates the development of packaging materials that possess enhanced thermal conductivity and substantial mechanical strength. In this paper, we present a novel type of CaO–B 2 O 3 –SiO 2 /β-Si 3 N 4 composites synthesized through the solid-state reaction. The effects of β-Si 3 N 4 ceramic content on the sinterability, phase structure, microstructure, and properties of the composites were studied. As an excellent structural and functional material, the rod-like β-Si 3 N 4 ceramic not only enhanced the thermal conductivity (λ) and flexural strength of composite materials but also effectively reduced the thermal expansion coefficient (CTE) of the composite and maintained good high-frequency dielectric properties. The composite sample containing 15wt.% β-Si 3 N 4 demonstrated exceptional performance after sintering at 850 ℃ for 30 min, achieving a bulk density of 2.80 g/cm 3 , a relative permittivity of 6.52 with a dielectric loss of 1.94 × 10 –3 (15 GHz), a λ of 3.5 W/(m·K), a CTE value of 6.40 ppm/ ℃, and a flexural strength of 180.1 MPa. Additionally, the EDS line mapping indicates that there was no diffusion of silver at the interface, thereby affirming the favorable compatibility between the composite and the silver electrode. This characteristic positions the CBS/β-Si 3 N 4 composite as a potentially promising candidate for applications in electronic packaging.