Doping ZnO in low boron calcium borosilicate glass-ceramics for high-performance dielectric LTCC substrate

CaO-B₂O₃-SiO₂ (CBS) glass-ceramics is one of the most widely used commercial low-temperature co-fired ceramic (LTCC) substrate materials due to its excellent dielectric and mechanical properties. However, medium-high boron CBS glass suffers from challenge such as difficulty in melting, volatility and phase separation, leading to its inability to balance the competition between sintering and crystallization. The introduction of ZnO to replace part of the B₂O₃ may be able to solve the above problems effectively. Specifically, the networks modifier ZnO can be used to reduce sintering temperatures by decreasing network aggregation in the glass. Our study found that the higher the content of ZnO, the more non-bridging oxygen in the glass network, the lower the temperature at which glass-ceramics can be sintered densified. With 4 mol % ZnO, the glass-ceramics can be densified at 850 °C with a dielectric constant of 5.29 and a dielectric loss of 3.12 × 10^–4 at 1 MHz and a bending strength of 174 MPa. This work presents a novel idea for the design of advanced glass-ceramics.