Ni electrode technology is now well established for multilayer ceramic capacitors (MLC's) but there is a continual drive to reduce the thickness of the dielectric layers. In the case of MLC's with X7R designation, a dielectric thickness of 2 μm, or less, is practicable when the fired grain size is not more than 250 nm. However, achieving adequate dielectric characteristics, such as breakdown voltage, HALT, TCC, DF and K, at this thickness is not possible unless high performance powders are used. In this paper we will describe a high purity barium titanate made by the semi-alkoxide process that consists of 0.4 μm monosize clusters of 40-60 nm crystallites. This type of powder provides some of the benefits of nanosized particles but allows processing into a slurry by standard techniques because of its relatively low surface area. For X7R applications, the barium titanate must be modified with dopants to achieve the necessary core-shell microstructure and compositional uniformity is essential for high reliability in thin layers. Accordingly, chemical-coating technology has been employed to achieve the necessary uniform distribution of dopant ions.
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