Low-Firing Double-Layered Thick-Film Capacitor

Double-layered thick-film capacitors, based on the superposition theorem, were prepared with the low-firing MnO2-modified Pb(Fe2/3W1/3)x(Fe1/2Nb1/2)0.86-xTi0.14O3-Bi2O3/Li2O thick-film dielectrics. Eutectic solid solution of Bi2O3/Li2O = 89/11(Tmelting= 700°C) was selected as a fluxing agent to promote densification during the firing process. Small amounts of MnO2was added to depress the temperature dependence of the loss tangent. A model of superposition was proposed to explain and simulate the variation of capacitance with temperature. By adjusting the thickness ratio between the two dielectric layers, the variation of capacitance with temperature could be reduced to ±4 percent in the temperature range of - 25 to 80°C. The double-layered thick-film capacitors can be fired at 870°C for 15 min.