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AssigneeDowa Electronics Materials Co., Ltd.
InventorsMasahiro Yoshida, Kenichi Inoue, Atsushi Ebara, Yoshiyuki Michiaki, Takahiro Yamada
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While a molten metal of copper heated to a temperature, which is higher than the melting point of copper by 250 to 700° C. (preferably 350 to 650° C. and more preferably 450 to 600° C.), is allowed to drop, a high-pressure water is sprayed onto the heated molten metal of copper in a non-oxidizing atmosphere (such as an atmosphere of nitrogen, argon, hydrogen or carbon monoxide) to rapidly cool and solidify the heated molten metal of copper to produce a copper powder which has an average particle diameter of 1 to 10 μm and a crystallite diameter Dx(200) of not less than 40 nm on (200) plane thereof, the content of oxygen in the copper powder being 0.7% by weight or less.
A copper powder which has an average particle diameter of 3.5 to 10 μm and a crystallite diameter Dx(200) of not less than 40 nm on (200) plane thereof, the copper powder consisting of 0.2% by weight or less of oxygen and the balance being copper and unavoidable impurities, the copper powder having a temperature of not lower than 580° C. at a shrinkage percentage of 1.0% in a thermomechanical analysis thereof.
Dependencies are inferred from the claim text.