Crystallization behavior and microwave dielectric properties of low loss MgO-Al2O3-SiO2-MnO2-ZnO and MgO-Al2O3-SiO2-GeO2 microcrystalline glass-ceramics for LTCC substrate applications

In this study, 21.9 mol% MgO - 20.3 mol% Al 2 O 3 - 54.6 mol% SiO 2 + 1.6 mol% MnO 2 + 1.6 mol% ZnO and 23.1 mol% MgO - 20.9 mol% Al 2 O 3 - 55.0 mol% SiO 2 + 1.0 mol%GeO 2 were prepared by low-temperature co-firing method. The effects of nucleating agents and sintering temperature on the crystallization behavior, microstructure and microwave dielectric properties of MASMZ and MASG glass-ceramics were investigated. It was found that both glass-ceramics were able to precipitate stable α-cordierite crystalline phases at relatively low temperatures. Crystallization kinetics analysis showed that MASMZ glass-ceramics crystallized more easily than MASG glass-ceramics. MASMZ glass-ceramics exhibited optimal dielectric properties at 925 °C: ε r = 4.74, tan δ = 8.1 × 10 −4 , τ f = -14 ppm/°C. MASG glass ceramics achieved optimal dielectric properties at 950 °C: ε r = 4.46, tan δ = 1.11 × 10 −3 , τ f = -27 ppm/°C. Especially, the excellent chemical stability and compatibility of MASMZ and MASG glass-ceramics with silver at high temperatures were verified, indicating the potential of MASMZ and MASG glass ceramics as LTCC substrate materials.