Boron network ion modulation and composite alumina densification sintering study of MABS glass for LTCC

In this paper, we investigated the effect of B₂O₃ content in borosilicate glass on the glass properties and the effect of particle-size gradation on the low-temperature co-fired ceramic composites of MABS (MO–Al₂O₃–B₂O₃–SiO₂) (M = Ca, Mg) glass composite with alumina after optimization of boron content. We prepared a series of MO–Al₂O₃–B₂O₃–SiO₂ glasses with different B₂O₃ contents and MABS glass/Al₂O₃ composites with different particle-size gradation pairings. The results showed that the appropriate amount of B₂O₃ content not only enhanced the glass network structure but also inhibited the precipitation of harmful crystalline phases. The optimized particle-size gradation promoted the sintering densification and improved the green tape stacking density, dielectric, and mechanical properties. The composites prepared by sintering the MABS glass with a B₂O₃ content of 9.5 wt% and a particle size of 3.0 μm with 7.71 μm Al₂O₃ at 830 °C exhibited good performance with a green tape density of 2.01 g/cm³, a sintered density of 3.12 g/cm³, a z-axis shrinkage of 17.10%, a dielectric constant of 8.26, a dielectric loss of 0.6 × 10^–3 (at 7 GHz), coefficient of thermal expansion 6.75 ppm/°C, and flexural strength 299 MPa, demonstrating broad application potential.