Study on sintering behaviors, microstructures, and dielectric properties of CaO–B2O3–SiO2/ZrSiO4 composites for LTCC applications

In this study, CaO–B 2 O 3 –SiO 2 (CBS) glass–ceramics were prepared and compounded with different contents of ZrSiO 4 . The sintering behavior, phase composition, microstructure, dielectric properties, thermal properties, and mechanical properties of this CBS glass–ceramic composite ZrSiO 4 ceramic system were investigated. The results show that CBS glass–ceramic can be sintered densely at 750 °C. However, the crystallinity is unexpectedly low and the dielectric properties are greatly damaged. Surprisingly, the addition of ZrSiO 4 improved the dielectric constant of the composites and achieved a dielectric adjustable in the range of 6.0–7.8. When the composite was sintered at 830 °C for 15 min with 35% ZrSiO 4 addition, the bulk density of the composite increased to 2.93 g/cm 3 . The dielectric constant measured at a high frequency of 13 GHz was 6.93 and the dielectric loss of 1.66 × 10 –3 . Accordingly, the addition of ZrSiO 4 reduced the thermal expansion coefficient of the composite to 6.1 ppm/°C and increased the flexural strength of the composite to 248 MPa.