An electronic element mounting substrate includes: a first substrate including a first principal face; a second substrate located inside the first substrate in a plan view of the electronic element mounting substrate, the second substrate being made of a carbon material; a third substrate located between the first substrate and the second substrate in the plan view, the third substrate being made of a carbon material; and a first mounting portion for mounting a first electronic element, the first mounting portion being located on the first principal face side in a thickness direction of the substrate. The second substrate and the third substrate each have a low heat conduction direction and a high heat conduction direction. The second substrate and the third substrate is arranged so that the low heat conduction directions thereof are perpendicular to each other, and the high heat conduction directions thereof are perpendicular to each other.

In a wiring base body of a printed wiring board, a conductive post including a wiring portion and a wiring are embedded in an insulating resin film. Therefore, even in a region in which a wiring portion is formed, the wiring base body is not increased in thickness. In addition, even in a region in which a wiring is formed, the wiring base body is not increased in thickness. Therefore, it is possible to obtain a printed wiring board having high flatness by stacking a plurality of wiring base bodies and constituting a printed wiring board.

A multilayer board includes a flexible substrate including insulating layers stacked and a pair of through-holes penetrating the insulating layers, and an interlayer connecting conductor in an opposing region in which the pair of through-holes opposes each other in a plan view of the insulating layers viewed from a stacking direction. A cross section of the flexible substrate taken in a lateral direction passing through the pair of through-holes and the interlayer connecting conductor and the stacking direction has a U or S shape. In the cross section, a curvature radius of an inner region located between the pair of through-holes is larger than a curvature radius of an outer region adjacent to the pair of through-holes on an outer side thereof.

In an electro-optical device, a flexible first wiring substrate and a flexible second wiring substrate, which are respectively coupled to a first terminal region and a second terminal region, extend while overlapping with each other, and a first mold material is provided between the first wiring substrate and the second wiring substrate. The second wiring substrate includes a base film having transmissivity, a wiring line provided at the base film, and a protective layer that covers the wiring line and is less transmissive than the base film. In the second wiring substrate, a light-transmission window in which the wiring line and the protective layer are not present in part is provided in a region thereof overlapping with the first mold material.

A circuit board includes an insulating layer; a capacitor which is provided in the insulating layer and includes a dielectric layer, a first conductor layer provided on a first surface of the dielectric layer and including a first opening part, and a second conductor layer provided on a second surface opposite to the first surface of the dielectric layer and including a second opening part at a position corresponding to the first opening part; a first conductor via provided in the insulating layer, penetrating the dielectric layer, the first opening part and the second opening part, and being smaller than the first opening part and the second opening part in plan view; a second conductor via provided in the insulating layer and making contact with the second conductor layer; and a third conductor layer provided on the insulating layer and electrically coupled to the first and the second conductor vias.

A printed circuit board is disclosed. The printed circuit board includes a first substrate portion, and a second substrate portion connected to the first substrate portion and having a flexible insulation layer which is bendable, and the second substrate portion includes a frame member inserted into the flexible insulation layer.

A radio frequency module is provided. A matching circuit includes an inductor which is connected in series to the power amplifier and is formed in a substrate. The substrate includes a ground layer, a low permittivity portion, and a high permittivity portion. The ground layer at least partially overlaps with a first input terminal of the low-noise amplifier in a plan view from a thickness direction of the substrate. The low permittivity portion at least partially overlaps with the first input terminal in a plan view from the thickness direction, and is provided between the first input terminal and the ground layer. The high permittivity portion is in contact with the inductor and has the permittivity greater than the permittivity of the low permittivity portion.

A flexible base substrate, a manufacturing method thereof, and a display device are provided. The flexible base substrate includes a first flexible substrate. The first flexible substrate includes: a first flexible film layer including a flexible film layer body, and a plurality of protrusions spaced apart from each other on a surface of a side of the flexible film layer body; a first spacer layer on the first flexible film layer and including a plurality of first islands spaced apart from each other; and a first groove between adjacent first islands. The first groove is filled with a first organic material, and a height of the first organic material is smaller than a height of the first groove in a direction perpendicular to the flexible film layer body.

A high-frequency board includes an insulating substrate, a first line conductor, and a second line conductor. The insulating substrate has an upper surface with a recess. The first line conductor is located on the upper surface of the insulating substrate. The second line conductor is located on the upper surface of the insulating substrate and extends parallel to the first line conductor with a space from the first line conductor as viewed from above. The recess is located between the first line conductor and the second line conductor, and has a lower dielectric constant than the insulating substrate.

A carrier structure is provided. A spacer is formed in an insulation board body provided with a circuit layer, and is not electrically connected to the circuit layer. The spacer breaks the insulation board body, and a structural stress of the insulation board body will not be continuously concentrated on a hard material of the insulation board body, thereby preventing warpage from occurring to the insulation board body.