A wiring board includes an insulating layer comprising organic resin with inorganic particles, a first metal layer on a first surface, and a second metal layer disposed on a second surface. The insulating layer has a thickness of 75-1000 μm and a storage modulus of 4 GPa-7 GPa. The first metal layer has a thickness of 1.5-10 μm and a coverage of 5%-25%. The second metal layer has a thickness of 3-10 μm or 25-100 μm and a coverage of 85% or more. A surface part of the insulating layer on the first metal layer side has a higher ratio of organic resin than a surface part of the insulating layer on the second metal layer side.

A wiring substrate includes a core substrate, and a build-up part laminated on the substrate and including resin insulating layers. The insulating layers include a first insulating layer, the build-up part includes a conductor layer on the first insulating layer, a second insulating layer on the first insulating layer and covering the conductor layer, and a recess penetrating through the second insulating layer and exposing portion of the conductor layer such that the conductor layer includes component mounting region that places an electronic component in the recess and a conductor pad forming bottom surface of the recess, the insulating layers include inorganic filler such that all insulating layers or all insulating layers other than the first insulating layer include the inorganic filler and that inorganic filler content rate of the first insulating layer is lower than inorganic filler content rate of the insulating layers other than the first insulating layer.

A printed circuit board includes an insulating layer; a metal pad disposed on one side of the insulating layer; a via hole penetrating through the insulating layer to expose at least a portion of the metal pad; and a via filling at least a portion of the via hole, wherein the via comprises a first metal layer and a second metal layer disposed on the first metal layer, and an average size of grains in the first metal layer and an average size of grains in the second metal layer are different from each other.

A wiring board of the present disclosure includes: a first insulating layer including a surface; a second insulating layer including un upper surface and a lower surface and locating above the surface of the first insulating layer; a wiring conductor layer formed on the surface of the first insulating layer, includes a via land; and a via hole conductor penetrating from the upper surface to the lower surface of the second insulating layer. The via hole conductor includes a via bottom being in contact with the via land. Crystal grains in the via bottom are smaller than crystal grains in the via land.

Provided is a conductive film that can be formed without using a vacuum deposition method and includes a material that is neither a noble metal nor a special carbon material as a conductive element for exhibiting conductivity. The conductive film provided includes an arrangement portion of semiconductor nanoparticles. When a cross section including the arrangement portion is observed, the semiconductor nanoparticles are arranged in line apart from each other in the arrangement portion. A conductivity C1 measured along at least one direction is 7 S/cm or more.

[Problem to be solved]

Provided is an electronic component having thermal insulation properties and insulation resistance, which can be suitably used for modularization by injection molding or the like.

[Means to Solve the Problem]

There is provided an electronic component comprising a circuit board on which an electronic element is mounted and a coating layer for coating the surface of the circuit board, wherein the coating layer comprises at least a thermoplastic resin and hollow particles; and the coating layer has a concentration gradient of hollow particles in the thickness direction such that the content of the hollow particles in the coating layer is lower on the face side in contact with the circuit board.

A printed circuit board includes an insulating layer; a metal pad disposed on one side of the insulating layer; a via hole penetrating through the insulating layer to expose at least a portion of the metal pad; and a via filling at least a portion of the via hole, wherein the via comprises a first metal layer and a second metal layer disposed on the first metal layer, and an average size of grains in the first metal layer and an average size of grains in the second metal layer are different from each other.

An interconnect substrate includes a first insulating layer, an interconnect layer formed on a first surface of the first insulating layer, and a second insulating layer formed on the first surface of the first insulating layer to cover the interconnect layer, wherein the second insulating layer includes a first resin layer and a second resin layer, the first resin layer covering at least part of a surface of the interconnect layer exposed outside the first insulating layer, the second resin layer covering the first resin layer, wherein both the first resin layer and the second resin layer contain a resin and a filler, and wherein a proportion of the resin in the first resin layer per unit area is higher than a proportion of the resin in the second resin layer per unit area.

A stretchable mounting board that includes a stretchable substrate having a main surface, a stretchable wiring disposed on the main surface of the stretchable substrate, a mounting electrode section electrically connected to the stretchable wiring, solder electrically connected to the mounting electrode section and including bismuth and tin, and an electronic component electrically connected to the mounting electrode section with the solder interposed therebetween. The mounting electrode section has a first electrode layer on a side thereof facing the stretchable wiring and which includes bismuth and tin, and a second electrode layer on a side thereof facing the solder and which includes bismuth and tin. A concentration of the bismuth in the first electrode layer is lower than a concentration of the bismuth in the second electrode layer.

A dispersion which contains a dispersant and particles selected from among metal particles and metal oxide particles, and which is characterized in that: the dispersant has a chemical structure that is able to be bonded or adsorbed to the particles; and the dispersant contains a low-molecular-weight dispersant that has at least one peak within a molecular weight region of 31 or more but less than 1,000 in the molecular weight distribution curve in terms of polyethylene glycol as determined by gel permeation chromatography and a high-molecular-weight dispersant that has at least one peak within a molecular weight region of 1,000 or more but 40,000 or less in the above-described molecular weight distribution curve.