Low temperature cofiring and dielectric properties of ca-doped Al₂O₃/K₂O₃–B₂O₃–SiO₂ composite ceramics for LTCC applications

Al₂O₃/K₂O₃–B₂O₃–SiO₂ low temperature cofired ceramics (LTCC) dielectric materials doped with CaCO₃ were prepared by using a solid-state reaction. The microstructure and dielectric properties of Al₂O₃/K–B–Si borosilicate, together with the effects of Ca doping, were investigated. A new material system candidate of Al₂O₃/KBSiO borosilicate doped by Ca was achieved after sintering at 880°C, which presents an optimized performance on dielectric properties with a permittivity «_r < 8 and dielectric loss tan d £ 0.002 and excellent stabilities across very broad frequency and temperature ranges. Most importantly, the initial results have also indicated that the new dielectric composite material is well compatible with the existing LTCC process, suggesting a considerable potential for practical LTCC applications.