Mitsui Minings & Melting Co., Ltd.

Takashi Mukuno

Takayuki Araki

Yoshiharu Toshima

Katsuhiko Yoshimaru

Kei Anai

Yoichi Kamikoriyama

Mikimasa Horiuchi

Sumikazu Ogata

Hiroki Sawamoto

It is an object of the present invention to provide a conductive ink which enables to form a circuit or the like having excellent adhesion to a substrate and to form a conductor having high film density and low electric resistance. In order to attain the object, a conductive ink comprising metal powder or metal oxide powder dispersed in a dispersion medium, which is characterized in that the dispersion medium contains a metal salt or a metal oxide as a film density improver for increasing film density of a conductor formed by using the conductive ink is adopted. A main solvent constituting the dispersion medium is selected from one or a combination of two or more selected from the group consisting of water, alcohols, glycols and saturated hydrocarbons having a boiling point of 300 deg. C. or less at normal pressure.

Conductive ink

Herein disclosed is surface-modified nickel fine powder in which a precursor of barium titanate having a perovskite structure and consisting of a reaction product of a soluble titanium-containing compound and a soluble barium-containing compound is adhered to the surface of individual nickel fine particles, wherein the fine powder shows X-ray diffraction peaks of nickel and is free of any peak of barium titanate having a perovskite structure in the X-ray diffraction pattern determined by the X-ray diffraction method, but the fine powder shows X-ray diffraction peaks of both nickel and barium titanate having a perovskite structure in the X-ray diffraction pattern after the fine powder is subjected to a heat-treatment at a temperature of not less than 400&deg; C. The nickel fine powder has a small heat shrinkage factor upon firing and improved resistance to oxidation. The powder permits the inhibition of any such phenomenon that nickel is oxidized and the oxidized nickel penetrates into a ceramic dielectric material during firing. The powder is suitable for use as a material for a conductive paste and, in particular, for forming a conductive paste used in making a multilayer ceramic capacitor.

Method for preparing surface-modified nickel powder

The nickel powder is characterized in that the rate of the nickel particles whose particle size is not less than 1.2 time the average particle size as determined by the observation with an SEM is not more than 5% of the total number of nickel particles and that the rate of nickel particles whose particle size is not more than 0.8 time the average particle size is not more than 5% of the total number of nickel particles. The nickel powder is produced by bringing a slurry, containing nickel hydroxide, which is prepared by adding an aqueous solution of a nickel salt to an aqueous solution of an alkali metal hydroxide, into contact with a hydrazine reducing agent under the temperature conditions of not less than 55&deg; C. to reduce the nickel hydroxide.

Nickel powder, method for preparation thereof and conductive paste

The present invention relates to nickel powder characterized in that the rate of the nickel particles whose particle size is not less than 1.2 time the average particle size as determined by the observation with an SEM is not more than 5% of the total number of nickel particles, that the rate of nickel particles whose particle size is not more than 0.8 time the average particle size is not more than 5% of the total number of nickel particles and that the tap density of the nickel powder is not less than 2.5 g/cm , as well as a conductive paste for use in making a multilayer ceramic capacitor. The nickel powder of the present invention has a narrow particle size distribution and an excellent packing ability in a conductive paste and is particularly suitably used for forming a thin and uniform inner electrode for a multilayer ceramic capacitor, without being accompanied by the formation of any crack and/or the generation of any delamination.

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Yamaguchi, Japan

Takashi Mukuno