A substrate for a printed wiring board, the substrate includes a base film containing polyimide as a main component and a sinter layer disposed on at least a portion of a surface of the base film and containing copper nanoparticles. The base film contains a nitrogen atom bonded to a copper atom of the copper nanoparticles, an average number of the nitrogen atom bonded to the copper atom per unit area of the surface of the base film on which the sinter layer is disposed is 2.6×10.sup.18 atoms/m.sup.2 to 7.7×10.sup.18 atoms/m.sup.2, and the average number is an average number calculated for a measurement region estimated to have a thickness of 3 nm from a measurement value of the surface of the base film measured by X-ray photoelectron spectroscopy.

Proposed are a flexible electrode circuit capable of being foamed through 3D circuit printing, a strain sensor using the same, and a manufacturing method thereof. The flexible electrode circuit includes a flexible substrate and an electrode foamed on the flexible substrate. The electrode includes a conductive line layer and a passivation layer. The conductive line layer includes a matrix including an elastic polymer and a conductive line having conductive liquid metal microparticles dispersed in the matrix. The passivation layer includes a coating portion coated on the conductive line and having an elastic polymer.

Embodiments of the present invention provide a method for producing a conductor. The method includes: applying a resin forming composition containing a polymerizable compound and a solvent on a substrate; polymerizing the polymerizable compound in the applied resin forming composition to form a resin structure that is porous on the substrate; and applying a conductor forming composition containing at least one selected from the group consisting of metal oxide particles and metal particles on the resin structure.

A formulation containing particulate matter including nanometric metallic copper particles, at least 10% of the particulate matter being single-crystal metallic copper particles, the particulate matter having an average secondary particle size (d.sub.50) within a range of 20 to 200 nanometers, the nanometric metallic copper particles being at least partially covered by at least one dispersant; a concentration ratio of crystalline cuprous oxide particles to the nanometric metallic copper particles, within the particulate matter, being at most 0.4; the formulation including a solvent, the particulate matter and the solvent forming a dispersion.

A reliable electronic circuit board is provided, which maintains the quality and electrical conduction of an electronic circuit thereof even if being produced at an ordinary temperature at an atmospheric pressure. The electronic circuit board includes an ink receiving layer formed from a resin composition containing a polyvinyl acetal resin as a main component, and an electronic circuit formed in a pattern from an electrically conductive ink. An electronic circuit board production method includes the steps of: applying a liquid resin composition containing a polyvinyl acetal resin as a main component to form a layer of the liquid resin composition; heat-drying the liquid resin composition to form an ink receiving layer; and forming an electronic circuit in a predetermined circuit pattern from an electrically conductive ink by a printing method or a transferring method.

A substrate for a printed circuit board according to an embodiment of the present invention includes a base film having insulating properties and a sintered layer formed of a plurality of metal particles, the sintered layer being stacked on at least one surface of the base film, in which a region of the sintered layer extending from an interface between the sintered layer and the base film to a position 500 nm or less from the interface has a porosity of 1% or more and 50% or less.

A conductive ink is provided, which includes an ink solvent and a conductive composition dispersed in the ink solvent. The conductive composition includes a silver nanoparticle and a molecular chain of polyaniline formed on a surface of the silver nanoparticle. A method for preparing a conductive ink and a flexible display device are further provided. The conductive ink has good film forming property and good conductivity.

A circuit forming method, comprising: a coating step of applying a metal-containing liquid and a metal paste in an overlapping manner on a base, the metal-containing liquid containing fine metal particles and the metal paste containing a resin binder and metal particles larger than the fine metal particles in the metal-containing liquid; and a heating step of making the metal-containing liquid and the metal paste coated in the coating step conductive by heating the metal-containing liquid and the metal paste.

A method of forming a conductive pattern includes forming a conductive pattern by ejecting a liquid-state material containing conductive fine particles onto a porous base material, wherein the conductive fine particles have an average particle size of from 1 nm to 200 nm, and the porous base material is formed with a plurality of cavities and includes communication holes through which the plurality of cavities are in communication, an average diameter of the communication holes being less than or equal to the average particle size of the conductive fine particles.

A method for manufacturing a wiring board capable of improving adhesion between an underlayer and a seed layer. An electrically conductive underlayer is disposed on the surface of an insulating substrate and a seed layer containing metal is disposed on the surface of the underlayer to prepare a substrate with seed-layer. A diffusion layer in which elements forming the underlayer and seed layer are mutually diffused is formed between the underlayer and the seed layer, by irradiating the seed layer with a laser beam. A metal layer is formed on the surface of the seed layer by disposing a solid electrolyte membrane between an anode and the seed layer as a cathode and applying voltage between the anode and the underlayer. An exposed portion without the seed layer of the underlayer is removed from the insulating substrate.