BaTiO3 films for multilayer devices by tape casting

Abstract

The diversity of the applicational scope of modern printed electronics relentlessly requires the improvement of operational properties simultaneously with reducing the overall dimensions of devices. One of the most effective ways to overcome this major obstacle is the reduction of functional layers thickness in respect to the size of the device. In the present article, we are discussing a simple way of practical implementation of miniaturization concept through the application of a well-known high-productive industrial method of tape casting for obtaining thin nanostructured ceramic layers based on BaTiO3 nanopowders for MLCC. Using of nanosized powders per se imply a new approach of developing suspensions with suitable rheology for tape casting. We demonstrate, that a length of polymer molecule defines the size of floccules and therefore influences the thickness and surface quality of tape casted films. A certain nanopowder/polymer ratio contributes to the formation of the tapes with the surface roughness comparable with the size of one nanoparticle (20-25 nm). Moreover, it was established that developed suspensions are extremely sensitive to temperature changes. Lowering the temperature significantly affects the flow character of suspension and thus the thickness of casted tapes. Considering this fact, we propose an effective self-developed pre-cooling method of nanopowder suspension casting, which allows obtaining extremely thin and smooth tapes with a thickness of less than 1 µm and surface roughness of 20–25 nm by tape casting method.