A new microwave ceramic with low-permittivity for LTCC applications

A new low-temperature microwave dielectric ceramic with low-permfttivity was found and investigated in the CaO-MgO-SiO2-TiO2 system. Phase constitutes and dielectric properties of (Ca1-x,Mg-x)SiO3 (x = 0.1-0.5) ceramics were studied with different x contents, and CaTiO3 demonstrated an effective compensation in (Ca1-x,Mg-x)SiO3 tau(f) value. The 0.88CaMgSi(2)O(6)-0.12CaTiO(3) Compositions show a relatively low-permittivity (similar to 9.42), high Q x f values up to 52,800GHz, andnear-zero temperature coefficients (5.6ppm/degrees C), which were obtained via sintering at 1300 degrees C. The addition of <= 2.Owt% Li2CO3-V2O5 was very effective in lowering the sintering temperature (T-s), and dense ceramics could be obtained at T-s <= 900 degrees C. The addition of LiCO3-V2O5 does not induce apparent degradation in the microwave properties. The specimens with 1 wt% Li2CO3-V2O5 sintered at 880 degrees C for 2 h shows excellent dielectric properties: epsilon(r) = 9.23, Q x f=46,200GHz, and tau(f) = 1.3 ppm/degrees C. The low-temperature sintering ceramics powders were suitable for the tape casting process. Also, the material is compatible with Ag electrodes, and therefore, is suitable for LTCC application. (c) 2007 Elsevier Ltd. All rights reserved.