A Cu core ball and a method of manufacturing such a Cu core ball. Purity of the Cu internal ball is at least 99.9% and not greater than 99.995%. A total contained amount of Pb and/or Bi in impurity contained in the Cu ball is equal to or larger than 1 ppm. Its sphericity is at least 0.95. A solder plating film coated on the Cu ball is of Sn solder or a lead free solder alloy whose primary component is Sn. In the solder plating film, a contained amount of U is not more than 5 ppb and that of Th is not more than 5 ppb. A total alpha dose of the Cu ball and the solder plating film is not more than 0./0200 cph/cm2. An arithmetic average roughness of the Cu core ball is equal to or less than 0.3 μm.

There is provided a silver-coated copper powder, which has excellent storage stability (reliability), and a method for producing the same. A silver-coated copper powder obtained by coating the surface of a copper powder, which is obtained by the atomizing method or the like, with 5 wt % or more (with respect to the silver-coated copper powder) of a silver containing layer of silver or a silver compound, is added to a gold plating solution, which is a potassium gold cyanide solution (to which at least one of tripotassium citrate monohydrate, anhydrous citric acid and L-aspartic acid is preferably added), to cause 0.01 wt % or more (with respect to the silver-coated copper powder) of gold to be supported on the surface of the copper powder coated with the silver containing layer.

Copper inks are provided that include a plurality of core-shell nanostructures, with each nanostructure including a copper core and a barrier metal shell, a diameter of less than about 500 nm, and a distinct boundary between the copper core and the barrier metal shell. Methods of forming a copper ink are further provided and include an initial step of synthesizing an amount of copper nanoparticles in an aqueous solution. An amount of a barrier metal is then added to the copper nanoparticles to form a dispersion of the barrier metal and the copper nanoparticles, and a reducing agent is subsequently added to the dispersion to produce a copper ink comprising core-shell nanostructures having a copper core and a barrier metal shell. Copper films are then formed by applying that copper ink to a substrate and sintering the copper ink.

An ink composition including a metal nanoparticle; at least one aromatic hydrocarbon solvent, wherein the at least one aromatic hydrocarbon solvent is compatible with the metal nanoparticles; at least one aliphatic hydrocarbon solvent, wherein the at least one aliphatic hydrocarbon solvent is compatible with the metal nanoparticles; wherein the ink composition has a metal content of greater than about 45 percent by weight, based upon the total weight of the ink composition; wherein the ink composition has a viscosity of from about 5 to about 30 centipoise at a temperature of about 20 to about 30° C. A process for preparing the ink composition. A process for printing the ink composition comprising pneumatic aerosol printing.

A barrier layer is disposed on a copper surface, the barrier layer including an organic molecule. The organic molecule may be a nitrogen-containing molecule. The nitrogen-containing organic molecule includes 1 to 6 carbon atoms. The barrier layer may be deposited on an exposed copper surface before deposition of a surface finish.

Provided is a conductive particle which can effectively suppress occurrence of connection failure. A conductive particle (1, 11, 21) according to the present invention is a conductive particle including a base particle (2) and a conductive portion (3, 12, 22) disposed on a surface of the base particle, in which a particle diameter of the conductive particle is 30 μm or more, and a ratio of a resistance value (R20) of the conductive particle after loading and unloading up to 20% compression deformation of the conductive particle are repeated 20 times to a resistance value (R1) of the conductive particle after loading and unloading up to 20% compression deformation of the conductive particle are performed once is 1.5 or less.

The invention relates to a process of fabricating a beaded path on the surface of a substrate, the process comprising: preparing a dispersion of particles in a liquid; supplying the prepared dispersion to at least one electrically conductive microcapillary in a continuous manner; forming and maintaining a convex meniscus of the dispersion at the outlet end of the microcapillary positioned above and/or below the surface of a substrate; applying alternating voltage to the microcapillary so that a beaded structure is formed between the dispersion meniscus and the surface of the substrate; and moving the microcapillary relative to the substrate and/or the substrate relative to the microcapillary so as to deposit the particles of the formed beaded structure on the surface of the substrate and simultaneously rebuild the beaded structure formed between the dispersion meniscus and the surface of a substrate. The invention also relates to a system for realizing this process and the use of the beaded path fabricated in accordance with the process of the invention for the production of electrodes in photovoltaic cells, new generation clothing, electronic components, including flexible electronics, artificial flagella, photonic and optomechanical materials, as well as for the regeneration of damaged paths on the surface of a substrate. The present invention also relates to a kit comprising a substrate and a beaded path fabricated on the surface of that substrate according to this process. The invented process is simple, efficient, hence economical, and enables fabricating beaded paths that retain their properties after turning off the voltage initially used to form a beaded structure. Moreover, the process occurs outside a liquid environment and enables fabricating of paths in a continuous manner, that is, through the formation of the beaded structure and its simultaneous depositing on the surface of a substrate allowing the fabrication of beaded paths of arbitrary length.

This invention is a flexible conductive ink composition comprising (A) a resin binder, (B) silver-plated core conductive particles, and (C) conductive particles having a surface area at least 1.0 m.sup.2/g.

Provided is a conductive paste which makes it possible to form a conductive layer having excellent conductivity even when spherical copper powder having a small particle diameter is used. Disclosed is a conductive paste containing a conductive filler and a binder resin. In this conductive paste, when a first coating film is prepared by coating a first paste containing 100 parts by weight of the binder resin and 20 parts by weight of the conductive filler on a first substrate at a coating amount of 100 g/m.sup.2 and drying and curing the binder resin, the first coating film has a light transmittance of 20% or more, and when a second coating film is prepared by coating a second paste containing the binder resin but not containing the conductive filler on a second substrate at a coating amount equivalent to a dry solid content of 55 g/m.sup.2 and drying and curing the binder resin, a film thickness t μm of the second coating film and a shrinkage ratio α % obtained by the following formula (1) satisfy a relationship of the following formula (2): α=(1−(arc length of a surface of the second coating film after drying and curing)/(arc length of a second substrate after drying and curing))×100 Formula (1) and α≥(5t+50)×10.sup.−3 Formula (2).

A barrier layer is disposed on a copper surface, the barrier layer including an organic molecule. The organic molecule may be a nitrogen-containing molecule. The nitrogen-containing organic molecule includes 1 to 6 carbon atoms. The barrier layer may be deposited on an exposed copper surface before deposition of a surface finish.