Method for manufacturing spherical ceramic-glass nanocomposite dielectrics for multilayer ceramic capacitor applications

摘要

Spherical ceramic-glass nanocomposite dielectrics made from ceramics and glasses that are separately pre-milled by mechanical ball milling using selected ball-to-powder weight ratios and combined to form a mixture that is ball milled. A stable liquid suspension of the milled mixture including an added dispersant such as polyacrylic acid to improve uniformity is spray dried through a nozzle and recovered product is annealed. The novel dielectrics have a microstructure where ceramic primary particles are uniformly distributed and fully embedded in a glass matrix. The dielectrics have a mean particle size of about 1-20 um and a sphericity of about 0.8 or higher which are suitable for fabricating multilayer ceramic capacitors for high temperature applications. The novel dielectrics afford decreased sintering temperature, enhanced breakdown strength, lower dielectric lose tangent, and lower costs. Calcium titanate zirconate with manganese-doping-based or barium titanate-based dielectric ceramics and alkali-free borosilicate glass produce superior nanocomposite dielectrics.