The thickness of BaTiO3 tape castings as function of the slip system
Résumé
One of the most popular techniques in the fabrication of multilayer ceramic capacitor (MLCC) is tape casting, which requires the preparation of a slip that could be either solvent or water-based. A requirement of MLCC miniaturization has pushed improvement of this technique up to the point of fabricating ceramic films below 10μm. However, less information on a direct comparison of aqueous and non-aqueous slips systems using BaTiO3 for dielectric tapes below 3.5 μm is available in the literature. Therefore, solvent and water-based systems were studied in this research aimed to weight the different factors on the thickness reduction; in particular the relation between slip viscosity and ceramic tape thickness was established for both slips formulations. It was found that viscosity below 100 mPa·s is a not a general rule since there is an important influence of the solvent medium; nevertheless adhesion tape-substrate plays an important role over the thinning of water-based formulations. The slip viscosity is defined by the dispersant type of aqueous systems and the binder of non aqueous systems, while reduction of the powder size is more sensitive to the solvent medium as for polar/non –polar mixtures. Ceramic tape homogeneity is strongly affected by the presence of hard aggregation and should be accounted for with the use of nanoparticles. A condition was also demonstrated where low viscosities and thinner layers are related.
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