Analysis and optimization of dielectric properties of cordierite-based glass composites for advanced LTCC applications

This study presents the development and optimization of cordierite/Bi₂O₃-ZnO-B₂O₃-SiO₂ (BZBS) glass composites for low-temperature co-fired ceramic applications, targeting a low dielectric constant and low dielectric loss, which are critical for 5G communication devices. The research employs an internal standard method based on Rietveld refinement to precisely analyze the phase composition under varying sintering temperatures, thereby uncovering the effects of reaction products and residual glass phases on the composite's properties. A key finding is that sintering at 750 °C yields a relative density of 77.83% and a CTE of 3.49 ppm/°C, closely matching that of silicon. This optimized process achieves an ultra-low dielectric constant and low dielectric loss (ε_r = 3.97, tan δ = 0.011, τ_f = −38.17 ppm/°C @1 MHz, ε_r = 2.79, tan δ = 0.005 @1 GHz). Additionally, three polarization relaxations- α, β and γ -were identified, providing insights into frequency-dependent dielectric behavior, which is essential for high-frequency applications. These results suggest that the optimized composite offers a balanced combination of dielectric stability, low loss, and thermal compatibility, making it a promising candidate for high-frequency LTCC substrates in next-generation microwave communications.