Study On BaO-Nd₂O₃-TiO₂ System Ceramic For Thick Film Circuit

With the rapid progress in communication technology, communication equipments are commonly developed for miniaturization, and in order to meet the requirements of high integration, low temperature co-fired ceramics not only with low dielectric dissipation but right temperature stability have a wonderful application foreground. This dissertation introduces the function of BZB and GE glass additives doping in the special composed BNT system ceramic. The effect on microwave dielectric properties and function mechanism of glass additions are also studied. Material ratios, arts and crafts are rectified at last and experiment conclusions are as follows.BaO-Nd₂O₃-TiO₂(BNT) system ceramic is an excellent material with good dielectric constant, but its sintering temperature is so high that it can not be co-fired with low melting point electrode materials such as Ag and Cu at 850℃. Firstly, we optimize the BNT ceramic via added the content of Bi₂O₃ so as to reduce its sintering temperature, then low softening point glass was added. Interaction between the low softening point glass and high melting point ceramic brings in a good wetting between BNT ceramic and glass additive, and make the sintering temperature drop simultaneously. Finally conditions of arts and crafts are adjusted to fulfill the needs of dielectric characteristics.The result indicate that 5wt% BZB doped BNT ceramic system whose general formula is Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄(x=0¹, y=0.5) sintered at 850℃has an excellent microwave dielectric property asε≈52, tanδ≈6×10^-3,αc≤2%, insulated resistance R≥1×10¹¹ when measured at 1MHz. On this basis we continuously investigate the effect of GE glass additive which is used as complex additives with BZB to decrease the sintering temperature. 5wt% BZB and 1wt% GE doped BNT ceramic system can be sintered at 850℃and has the dielectric properties ofε≈55.9,tanδ≈2×10^-3(1MHz),αc≤2%, insulated resistance R≥1×10¹¹.The material studied in this thesis can be used to make LTCC capacitor of BNT system ceramic for thick film circuit and so on. By right of its unique excellence, it will become the first choice of electronic integration and modularization and it will also have good application market and development foreground in the future.