Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.

Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.

Abstract: When copper powder manufactured by a wet reduction method is kneaded with resin in a high filling rate, it is difficult to maintain a low viscosity. The invention is to solve the problem of high viscosity without changing the characteristics such as particle size and specific surface area of the copper powder obtained by a wet reduction method. This invention relates to copper powder for an electrically conductive paste wherein copper powder manufactured by a wet reduction method is subjected to a surface-flattening treatment in which the particles are mechanically collided each other.

Abstract: A copper powder is provided that has an average particle diameter in the range of from not less than 0.1 ?m to less than 1.5 ?m, that has a narrow particle size distribution width whose value A defined by Equation (1) below in terms of X25, X50 and X75 defined below is not greater than 1.2, and that forms a pseudo-fused sintered product when held at a temperature of 800° C. under an atmosphere of inert gas at one atmosphere pressure: A=(X75?X25)/X50??(1), where X25, X50 and X75 are values of particle diameter X corresponding to Q %=25%, 50% and 75% on a cumulative particle-size curve plotted in an orthogonal coordinate system whose abcissa represents particle diameter X (?m) and ordinate represents Q % (ratio of particles present of a diameter not greater than the corresponding value of X; expressed in units of vol % of particles). The copper powder is produced by conducting wet reduction of cuprous oxide into metallic copper powder in the presence of ammonia or an ammonium salt.

Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.

Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.

Abstract: When copper powder manufactured by a wet reduction method is kneaded with resin in a high filling rate, it is difficult to maintain a low viscosity. The invention is to solve the problem of high viscosity without changing the characteristics such as particle size and specific surface area of the copper powder obtained by a wet reduction method. This invention relates to copper powder for an electrically conductive paste wherein copper powder manufactured by a wet reduction method is subjected to a surface-flattening treatment in which the particles are mechanically collided each other.

Abstract: A copper powder is provided that has an average particle diameter in the range of from not less than 0.1 &mgr;m to less than 1.5 &mgr;m, that has a narrow particle size distribution width whose value A defined by Equation (1) below in terms of X25, X50 and X75 defined below is not greater than 1.2, and that forms a pseudo-fused sintered product when held at a temperature of 800° C.

Abstract: Silver-dispersed copper powder whose particles have substantially no discrete metallic silver on their surfaces is produced by subjecting a silver-adhered copper powder composed of copper particles having silver adhered to the surfaces thereof to heat treatment in a non-oxidizing atmosphere at a temperature of 150-600° C. A conductive paste using the powder as filler resists migration.

Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.

Abstract: A copper powder is provided that has an average particle diameter in the range of from not less than 0.1 &mgr;m to less than 1.5 &mgr;m, that has a narrow particle size distribution width whose value A defined by Equation (1) below in terms of X25, X50 and X75 defined below is not greater than 1.2, and that forms a pseudo-fused sintered product when held at a temperature of 800° C.