COPPER FINE PARTICLE, CONDUCTIVE PASTE COMPOSITION, AND THEIR PRODUCTION METHODS

摘要

PROBLEM TO BE SOLVED: To provide copper fine particles, suitable as a raw material of a powder alloy or conductive paste, with high industrial efficiency at a low cost without depending on the particle diameter of an electrolytic copper powder as a raw material to be crushed and without depending on smoothing of a copper fine powder surface by mechanical means or the oxidation of the copper fine powder surface.SOLUTION: Copper fine particles of the present invention have a 50% diameter (D50) in volume-based cumulative fractions of the particle diameter distribution measured by a laser diffraction scattering method of 0.5μm or more and 10μm or less, have a ratio (Cs/Sv) of specific surface area (Cs) obtained by calculation when the particle is regarded as a sphere having a diameter D50 to specific area (Sv) measured by the BET method of 0.2 or more. The copper fine particles are obtained by including a smoothing process S4 of smoothing the unevenness of copper oxide film-coated copper fine particles where a copper oxide film is formed on their surface. Preferably, the smoothing process S4 includes a step of supplying the copper oxide film-coated copper fine particles into acid.