Emulsified Ni paste for damage-free coating on BaTiO3/polymer dielectric composite layer in MLCCs

ABSTRACT The interaction between the dielectric BaTiO3/poly(vinyl butyral) composite layer (BT@PVB sheet) and the metallic Ni/ethyl cellulose composite layer (Ni@EC sheet) in developing MLCC has been considered an inevitable factor. In this paper, we devised Ni/polymer composite solution (Ni@EC paste) with new concept, which does not damage the dielectric composite layer underneath due to its lack of interaction with the BT@PVB sheet, and introduced emulsified-state suspension as a systematic template. Emulsified Ni@EC paste consists largely of hydrophobic phases, water phases, and PVB surfactants. The components that make up the hydrophobic phase were Ni nanoparticles, EC binders, and organic solvents. Within the emulsified paste (Ni@EC/water), the hydrophobic phase formed the structure of droplets surrounded by surrounding water, resulting in only the water phase being exposed to the outside. During the coating process, the water phase in Ni@EC/water emulsion paste came into contact with the as-prepared BT@PVB sheet, and the hydrophobic phase could not affect the sheet due to the blocking effect of the surrounding water phase. Afterwards, organic solvents as well as water were co-evaporated through the drying process, and most of the organic solvents were removed and solidified before molecular diffusion into BT@PVB sheet occurred. Graphical abstract