Abstract: A signal transmission line includes a signal region that includes a signal conductor layer and insulating base material layers, and a first ground region that includes a first ground conductor layer and insulating base material layers and is located above the signal region. The signal region is not fixed to the first ground region in a first section of a base. One or more first spacers are fixed to the signal region and in contact with the first ground region without being fixed thereto, or are in contact with the signal region without being fixed thereto and fixed to the first ground region. The one or more first spacers are in the first section.

Abstract: A signal transmission line includes first and second base materials, and conductive bonding materials. The first base material includes a signal conductor. The second base material includes a ground conductor. The conductive bonding materials bond the first base and second base material to provide a gap. The first base material includes a mounting conductor to which the conductive bonding materials are respectively bonded. The mounting conductor includes a portion extending in parallel or substantially in parallel with the signal conductor on a side of a first side surface, and a portion extending in parallel or substantially in parallel with the signal conductor on a side of a second side surface. A position of a portion of the mounting conductor on the side of the first side surface and a position of a portion of the mounting conductor on the side of the second side surface are different from each other in a signal transmission direction.

Abstract: An electronic device includes a first substrate and a second substrate. On or in the first substrate, a signal conductor extending in a transmission direction of a high-frequency signal and including a turn portion when viewed in plan is provided. On or in the second substrate, a base overlapping the signal conductor in plan view and including a turn portion while extending along the signal conductor is provided. The base is defined by, for example, a metal plate, has electrical conductivity, and serves as a ground conductor. A gap is provided between the signal conductor and the base having electrical conductivity.

Abstract: In a transmission line, a signal conductor layer extends in a front-back direction orthogonal to an up-down direction. A ground conductor layer is above the signal conductor layer. When viewed in a first orthogonal direction, first hollow portions are arranged in the front-back direction in a first direction of the signal conductor layer, and second hollow portions are arranged in the front-back direction in a second direction of the signal conductor layer. Each of regions between adjacent first hollow portions in the front-back direction is a first region. Each of regions between adjacent second hollow portions in the front-back direction is a second region. Each of the first hollow portions overlaps with a corresponding one of the second regions when viewed in a second orthogonal direction. Each of the second hollow portions overlaps with a corresponding one of the first regions when viewed in the second orthogonal direction.

Abstract: In a circuit module, a mounting electrode is located on a positive main surface of a resin layer positioned farther toward a positive side of a Z axis than other resin layers. An inner conductive layer overlaps the mounting electrode. An end of a first interlayer connection conductor on the positive side contacts the mounting electrode. An end of the first interlayer connection conductor on a negative side of the Z axis contacts the inner conductive layer. A product includes a connector bonded to the mounting electrode. The first interlayer connection conductor includes first and second regions provided in a direction toward the negative side in this order. A material of the first region is the same as that of the mounting electrode. A Young's modulus of the second region is lower than that of the first region.

Abstract: In a multilayer board, conductor layers include a first conductor layer including a mounting electrode on a positive main surface of an insulator layer located farthest in a Z-axis positive direction of insulator layers. One or more first interlayer connection conductors connect two of the conductor layers located on a positive main surface and a negative main surface of a first insulator layer. The one or more first interlayer connection conductors each include a first region and a second region with a lower thermal conductivity than the first region and located on a Z-axis negative direction side of the first region. The one or more first interlayer connection conductors include one or more large-area first interlayer connection conductors with a larger area than a second interlayer connection conductor when viewed in a Z-axis direction.

Abstract: In a multilayer substrate, a second multilayer body is positioned in a positive direction of a Z-axis of a first multilayer body. The second multilayer body is fixed to the first multilayer body via a first insulator layer bonded to a second insulator layer. Regions obtained by dividing the first multilayer body into three equal portions in the Z-axis direction are defined as a positive region, an intermediate region, and a negative region. A portion of one or more positive region first conductor layers is located in the positive region. An entirety of one or more intermediate region first conductor layers is located in the intermediate region. A thickness in the Z-axis direction of at least one of the one or more positive region first conductor layers is larger than the thickness in the Z-axis direction of the one or more intermediate region first conductor layers.

Abstract: A transmission line includes a first structure including a first insulating substrate and a ground conductor on the first insulating substrate, a second structure including a second insulating substrate and a signal line, ground conductors, and interlayer connection conductors on or in the second insulating substrate, a third insulating substrate including openings, and metal bonding materials that bond the structure and the structure to each other with the third insulating substrate interposed therebetween. The first and second insulating substrates are stacked with the third insulating substrate interposed therebetween to define hollow portions. The signal line and the ground conductor partially face each other across the hollow portions in a bonding direction. The ground conductor includes openings in regions that overlap the signal line but do not overlap the hollow portions when looking in plan view in the bonding direction.

Abstract: A multilayered substrate includes first, second, and third insulating layers, and a transmission line. The first insulating layer includes first and second surfaces opposite to each other. A signal conductor of the transmission line is on the first surface of the first insulating layer. The second insulating layer is in contact with the first surface of the first insulating layer. The third insulating layer is in contact with the second surface of the first insulating layer. A dielectric loss of the second insulating layer is lower than a dielectric loss of the third insulating layer. A degree of close contact between the first insulating layer and the third insulating layer is higher than a degree of close contact between the first insulating layer and the second insulating layer.

Abstract: A resin multilayer substrate includes a multilayer body including resin base-material layers laminated in a thickness direction and a circuit conductor therein, an end-surface ground conductor provided directly on each end surface of the multilayer body in the thickness direction, an adhesion layer on a side surface of the multilayer body, and a side-surface ground conductor on the adhesion layer. The end-surface and side-surface ground conductors are made of a ground conductor material with a coefficient of thermal expansion whose difference from a coefficient of thermal expansion of the resin base-material layers in a plane direction is smaller than a difference from a coefficient of thermal expansion of the resin base-material layers in the thickness direction. The adhesion layer is made of a material with higher adhesiveness to the side surface of the multilayer body than adhesiveness of the ground conductor material.

Abstract: In a multilayer board, a transmission line includes layers including a first insulator layer, a first joining material layer in contact with a first surface of the first insulator layer, and a second joining material layer in contact with a second surface of the first insulator layer. A signal conductor of the transmission line is on the first surface of the first insulator layer, a relative permittivity of the second joining material layer is lower than a relative permittivity of the first joining material layer, and an adhesion strength between the first insulator layer and the first joining material layer is higher than an adhesion strength between the first insulator layer and the second joining material layer.

Abstract: A transmission line includes a first structure including a first flexible resin base material, and a first ground conductor thereon, a second structure including a second flexible resin base material, and a first signal line and an interlayer connection conductor in or on the second resin base material, a first spacer between the first and second structures, and a first metal joining material joining the first and second structures with the first spacer interposed therebetween. A first hollow portion is between the first and second structures with the first spacer interposed therebetween. The first signal line and the first ground conductor face each other in a joining direction with the first hollow portion interposed therebetween. The first resin base material and the second resin base material are not in contact with each other. The first metal joining material has a melting point lower than that of the interlayer connection conductor.

Abstract: A first conductive layer is in contact with a first inter-layer connection conductor and a second inter-layer connection conductor. The first conductive layer has a same composition as the first and second inter-layer connection conductors. At least one first metal foil layer is in contact with a third main surface of the first conductive layer. The at least one first metal foil layer overlaps the first and second inter-layer connection conductors when viewed in a first direction. At least one second metal foil layer overlaps the first and second inter-layer connection conductors when viewed in the first direction, and is electrically connected to the first and second inter-layer connection conductors. The at least one second metal foil layer has a composition different from that of the first conductive layer.

Abstract: A multilayer substrate includes a multilayer body including resin layers stacked in a Z-axis direction, a signal conductor layer, and one or more through conductors passing through a first resin layer in the Z-axis direction. A first main surface of the first resin layer includes one or more hollow portions not in contact with the signal conductor layer and overlapping the signal conductor layer when viewed in the Z-axis direction. Each of the one or more hollow portions and the one or more through conductors includes a tapered region in which each of a cross-sectional area of the one or more hollow portions orthogonal to the Z-axis direction and a cross-sectional area of the one or more through conductors orthogonal to the Z-axis direction increases toward the first main surface. The tapered region is in contact with the first main surface of the first resin layer.

Abstract: An antenna element includes an insulative substrate including first and second main surfaces arranged in an up-down direction. At least one antenna conductor layer is provided on the first main surface of the insulative substrate. At least one insulative substrate non-forming region is provided between the insulative substrate and the antenna conductor layer in the up-down direction. An insulator layer does not exist in the at least one insulative substrate non-forming region. When seen in the up-down direction, all of an outer boundary of at least one antenna conductor overlaps the at least one insulative substrate non-forming region and is not in contact with the insulative substrate. At least one of the at least one insulative substrate non-forming region includes a void.

Abstract: An antenna element includes a first opening including an annular outer boundary in an antenna conductor layer. A first insulative substrate non-forming region is provided between an insulative substrate and the antenna conductor layer in an up-down direction. The insulative substrate does not exist in the first insulative substrate non-forming region. The outer boundary of the first opening overlaps one or more first insulative substrate non-forming regions and is not in contact with the insulative substrate. The first insulative substrate non-forming region is a first void, and a low dielectric constant material having a lower dielectric constant than that of a material of the insulative substrate or a high dielectric constant material having a higher dielectric constant than that of the material of the insulative substrate is provided in the first insulative substrate non-forming region.

Abstract: A multilayer substrate includes a multilayer body including insulation layers stacked on top of one another in an up-and-down direction. The insulation layers include a porous insulation layer. The multilayer substrate includes a first region and a second region. A dimension of the porous insulation layer in the up-and-down direction is smaller in the first region than in the second region. An average void size of the porous insulation layer is smaller in the first region than in the second region, and/or the porous insulation layer is denser in the first region than in the second region.

Abstract: A transmission line includes an element body, a signal conductor layer, and a ground conductor layer. The element body includes an insulator layer. The signal conductor layer is below the insulator layer, and the ground conductor layer is above the insulator layer in an element body up-down direction. A hole is located at a surface of the insulator layer and penetrates the insulator layer in the element body up-down direction. At least a portion of the hole overlaps the signal conductor layer when viewed in the element body up-down direction. The hole extends between a left hole-defining surface and a right hole-defining surface. In a cross section orthogonal to the element body front-back direction, the left hole-defining surface includes a left upper end and a left lower end in the element body left-right direction, and the right hole-defining surface includes a right upper end and a right lower end in the element body left-right direction.

Abstract: In a transmission line, a multilayer body includes a hollow portion above a signal conductor layer and below a ground conductor layer and overlapping the ground conductor layer when viewed in an up-down direction, and a spacer facing the hollow portion. In a cross section orthogonal to a front-back direction, an overlapping region is a region in the hollow portion in which the hollow portion overlaps the spacer in the up-down direction. In a cross section orthogonal to the front-back direction, a non-overlapping region is a region in the hollow portion in which the hollow portion does not overlap the spacer in the up-down direction. A length of the hollow portion in the up-down direction in the overlapping region is shorter than a length of the hollow portion in the up-down direction in the non-overlapping region.

Abstract: A multilayer substrate includes layers stacked on each other in an up-down direction of a multilayer body. The layers include a first spacer, a first ground conductive layer above the first spacer, and a signal conductive layer that overlaps the first ground conductive layer and is located below the first spacer. First through-holes pass through the first spacer and are arranged along a first direction. A distance between centroids of first through-holes adjacent to each other in the first direction is uniform or substantially uniform. Sets of first through-holes are provided in the first spacer. Sets of first through-holes are arranged along a second direction. A distance between centroids of first through-holes adjacent to each other in the second direction is uniform or substantially uniform. At least one first through-hole is a first hollow through-hole overlapping the signal conductive layer.