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 may include obtaining a printed circuit board (PCB) that includes a set of vias that include a set of stub regions. The PCB may include a set of layers perpendicular to the set of vias. The set of layers may include a signal layer and a ground layer. The ground layer may be located between the set of stub regions and the signal layer. The method may include drilling to remove at least a portion of a stub region of a via of the set of vias. The method may include performing an electrical test to determine whether a sliver of conductive material is included within the via after drilling to remove the at least a portion of the stub region of the via.

A multilayer printed circuit board includes a plurality of conductive layers formed by a conductive material, in which a blank region with the conductive material removed is formed in at least part of at least an intermediate conductive layer that is formed inside the multilayer printed circuit board, among the plurality of conductive layers, a plurality of island regions are formed by the conductive material included in the intermediate conductive layer in the blank region, and each of the plurality of island regions is not electrically connected to other regions included in the intermediate conductive layer and is disposed so as to be dispersed from one another.

A multilayer printed circuit board includes a plurality of conductive layers formed by a conductive material, in which a blank region with the conductive material removed is formed in at least part of at least an intermediate conductive layer that is formed inside the multilayer printed circuit board, among the plurality of conductive layers, a plurality of island regions are formed by the conductive material included in the intermediate conductive layer in the blank region, and each of the plurality of island regions is not electrically connected to other regions included in the intermediate conductive layer and is disposed so as to be dispersed from one another.

According to the present invention, there is provided a copper/ceramic bonded body including: a copper member made of copper or a copper alloy; and a ceramic member made of silicon-containing ceramics, the copper member and the ceramic member being bonded to each other, in which a maximum indentation hardness in a region is set to be in a range of 70 mgf/μm.sup.2 or more and 150 mgf/μm.sup.2 or less, the region being from 10 μm to 50 μm with reference to a bonded interface between the copper member and the ceramic member toward the copper member side.

According to the present invention, there is provided a copper/ceramic bonded body including: a copper member made of copper or a copper alloy; and a ceramic member made of silicon-containing ceramics, the copper member and the ceramic member being bonded to each other, in which a maximum indentation hardness in a region is set to be in a range of 70 mgf/μm.sup.2 or more and 150 mgf/μm.sup.2 or less, the region being from 10 μm to 50 μm with reference to a bonded interface between the copper member and the ceramic member toward the copper member side.

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.

An organic interposer includes: a first organic insulating layer including a groove; a first metal wire located in the groove; a barrier metal material covering the first metal wire; and a second metal wire located above the first metal wire, wherein the barrier metal material includes: a first barrier metal film interposed between the first metal wire and an inner surface of the groove; and a second barrier metal film located on the first metal wire, and wherein the second metal wire is in contact with both of the first barrier metal film and the second barrier metal film.

A wiring board includes: a substrate having transparency; a plurality of first wirings which are arranged on an upper surface of the substrate and extend in a first direction and each of which has a back surface in contact with the substrate and a front surface facing an opposite side of the back surface; and has a back surface in contact with the substrate and a front surface facing an opposite side of the back surface. The first wiring has a pair of side surfaces which extend in the first direction and are adjacent to the back surface of the first wiring, and each of the pair of side surfaces of the second wiring is recessed inward. The second wiring has a pair of side surfaces which extend in the second direction and are adjacent to the back surface of the second wiring.