A wiring board according to the present disclosure includes a first insulating material layer having a surface with an arithmetic average roughness Ra of 100 nm or less, a metal wiring provided on the surface of the first insulating material layer, and a second insulating material layer provided to cover the metal wiring, in which the metal wiring is configured by a metal layer in contact with the surface of the first insulating material layer and a conductive part stacked on a surface of the metal layer, and a nickel content rate of the metal layer is 0.25 to 20% by mass.

A multilayer resin substrate includes insulating resin base material layers, and conductor patterns on at least one of the insulating resin base material layers. The conductor patterns include a ground conductor on a main surface of the insulating resin base material layers and extend into a frame shape or a planar shape, and the ground conductor includes openings. An aperture ratio of the openings in an outer peripheral portion of the ground conductor is less than an aperture ratio of the openings in an inner peripheral portion of the ground conductor.

The polyimide resin precursor in the present embodiment is a polyimide resin precursor obtained by allowing a diamine component and a tetracarboxylic acid anhydride component to react with each other, wherein based on the whole of the diamine component, the content of p-phenylenediamine is 75 mol % or more; the tetracarboxylic acid anhydride component includes an ester-containing tetracarboxylic acid anhydride represented by formula (1), and at least one biphenyltetracarboxylic acid anhydride selected from the group consisting of 3,4,3′,4′-biphenyltetracarboxylic acid dianhydride, 2,3,3′,4′-biphenyltetracarboxylic acid dianhydride and 2,3,2′,3′-biphenyltetracarboxylic acid dianhydride; and based on the whole of the tetracarboxylic acid anhydride component, (i) the total of the content of the ester-containing tetracarboxylic acid anhydride and the content of the biphenyltetracarboxylic acid anhydride is 75 mol % or more, and (ii) the content of the ester-containing tetracarboxylic acid anhydride is 15 to 80 mol %, and the content of the biphenyltetracarboxylic acid anhydride is 85 to 20 mol %.

A polyphenylene ether resin composition includes a modified polyphenylene ether copolymer, a high-molecular-weight compound, and a crosslinking agent for the modified polyphenylene ether copolymer. The modified polyphenylene ether copolymer includes a substituent having a carbon-carbon unsaturated double bond at a molecular chain end of the modified polyphenylene ether copolymer. The high-molecular-weight compound has a glass transition temperature (Tg) measured by differential scanning calorimetry of 20° C. or lower and has a number-average molecular weight Mn ranging from 1000 to 10000, inclusive. The crosslinking agent includes at least two carbon-carbon unsaturated double bonds per molecule, and includes at least one of dicyclopentadiene acrylate and dicyclopentadiene methacrylate. In a cured state of the polyphenylene ether resin composition, the modified polyphenylene ether copolymer is phase separated from the high-molecular-weight compound.

A smart functional leather assembly includes a leather substrate, an electronic circuit layer including one or more conductive traces and optional electronic elements arranged on the leather substrate, optionally a pigmented coating arranged on the circuit layer, and an optional anti-soiling layer arranged on the pigmented layer. The entire smart functional leather assembly, including the circuit, are embossed to provide an embossed smart functional leather assembly with an embossed pattern.

A printed circuit board includes a substrate and wiring provided on a surface of the substrate and including a cured conductive paste. The conductive paste contains metal nanoparticles having an average particle diameter of 30 nm or more and 600 nm or less, metal particles having an average particle diameter larger than that of the metal nanoparticles, a thermosetting resin having an oxirane ring in a molecule, a curing agent, and a cellulose resin. The wiring has a width of 0.3 mm or more and 6 mm or less, a thickness of 10 μm or more and 40 μm or less, and a resistance value of 500 mΩ/m or more and 5000 mΩ/m or less, and a welding strength of the electronic component to the substrate is 30 N or more.

A printed-circuit board includes: a film-shaped thermoplastic base member having plasticity; a pattern fuse formed from a metal foil layer provided on a principal surface of the base member; a cover member covering at least part of the pattern fuse from an opposite side of the base member; and a first heat-resistant protection film provided on a region overlapping with at least part of the pattern fuse and covering the pattern fuse from a cover member side.

Provided are a laminate, a circuit board, and a liquid crystal polymer (LCP) film comprised therein. The laminate comprises a metal foil and an LCP film. The LCP film in the laminate has a dissipation factor before water absorption (Df′.sub.0), a dissipation factor after water absorption (Df′.sub.1), and a relative percentage difference between dissipation factors (ΔDf′), which is calculated by the following equation: $\Delta {\mathrm{Df}}^{\prime }\left(\%\right)=\frac{.Math.{\mathrm{Df}}_1^{\prime }-{\mathrm{Df}}_0^{\prime }.Math.}{{\mathrm{Df}}_0^{\prime }}\times 100\%;$
wherein ΔDf′ may be less than or equal to 16%. By controlling ΔDf′ of the LCP film in the laminate, the insertion loss of a circuit board comprising a laminate during signal transmission in low-, medium-, and/or high-frequency bands is decreased and/or inhibited. In addition, the difference between the insertion losses of signal transmission before and after water absorption is decreased, so the laminate is suitable for high-end or outdoor high-frequency electronic products.

An electronic circuit (4) comprises at least one electrically conductive portion arranged to a substrate (2) and at least one electrical coupling point (5) determined at the at least one electrically conductive portion. The electronic circuit (4) comprises at the at least one electrical coupling point (5) at least one magnetic and electrically conductive coupling element (6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k, 6l) for providing an electrically conductive coupling point (5) with magnetic fastening force.

A method of producing a thermoplastic liquid-crystal polymer film includes forming a thermoplastic liquid-crystal polymer film having opposite surfaces by molding a thermoplastic liquid-crystal polymer, melting the thermoplastic liquid-crystal polymer film by heating the thermoplastic liquid-crystal polymer film with the opposite surfaces being in contact with two support sheets at a temperature of from a melting point of the thermoplastic liquid-crystal polymer to a temperature higher than the melting point by 70° C., cooling the melted thermoplastic liquid-crystal polymer film to a temperature equal to or less than a crystallization temperature of the thermoplastic liquid-crystal polymer at a cooling rate of from 3° C. per second to 7° C. per second, and separating the cooled thermoplastic liquid-crystal polymer film from the support sheets.