Sintering Behaviors, Microstructures, and Dielectric and Thermal Properties of CBS/Mg₂SiO₄ Composite for LTCC Application

The (1−x)CaO-B₂O₃-SiO₂(CBS)/xMg₂SiO₄ composites were prepared and the influence of CBS crystallizable glass content on the sintering properties, dielectric properties, and thermal properties of the composites were investigated. The primary crystal phases in the CBS/Mg₂SiO₄ composites were CaMgSi₂O₆ and CaB₂O₄. An appropriate amount of Mg₂SiO₄ reduced the crystallization temperature of the composite. For x = 0.30, a sintering temperature of 890°C with a holding time of 60 min resulted in a bulk density of 2.645 g/cm³, dielectric constant of 6.6, and dielectric loss of 2.54 × 10⁻³ at 10 kHz. Prolonged holding time promotes grain growth; when extended from 60 min to 180 min for x = 0.30, the permittivity increased from 6.5 to 6.6 and Q×f increased from 10,100 GHz to 15,700 GHz when x = 0.30 at 13 GHz. The CTE of 70 wt.% CBS + 30 wt.% Mg₂SiO₄ composite was 9.5 ppm/°C, which approached the value of a circuit board for a ceramic ball grid array package (CBGA).