Abstract: A first substrate includes a first surface and a second surface opposite to the first surface. A second substrate includes a third surface and a fourth surface opposite to the third surface. A third substrate includes a fifth surface and a sixth surface opposite to the fifth surface. The first substrate is made of an insulator, and includes a mounting portion for mounting an electronic element at the first surface, and the mounting portion is a rectangular shape. The third substrate is made of a carbon material, and the fifth surface is connected to at least the second surface at location overlapped with the mounting portion in plan view. The third substrate has a larger heat conduction in a direction perpendicular to the longitudinal direction of the mounting portion than heat conduction in the longitudinal direction of the mounting portion in plan view.

Abstract: An electronic element mounting substrate includes a first substrate that has a first main surface, has a rectangular shape, and has a mounting portion for an electronic element on the first main surface, and a second substrate that is located on a second main surface opposite to the first main surface, is made of a carbon material, has a rectangular shape, has a third main surface facing the second main surface and a fourth main surface opposite to the third main surface, in which the third main surface or the fourth main surface has heat conduction in a longitudinal direction greater than heat conduction in a direction perpendicular to the longitudinal direction, and that has a recessed portion on the fourth main surface.

Abstract: A substrate for mounting electronic element includes: a first substrate including a first surface and a second surface opposite to the first surface; a second substrate including a third surface and a fourth surface opposite to the third surface; and heat dissipation bodies each including a fifth surface and a sixth surface opposite to the fifth surface. The first substrate includes at least one mounting portion for at least one electronic element at the first surface. Heat conduction of the heat dissipation bodies in a direction perpendicular to a longitudinal direction of the at least one mounting portion and perpendicular to a direction along opposite sides of the second substrate is greater than heat conduction of the heat dissipation bodies in the longitudinal direction of the at least one mounting portion and in the direction along opposite sides of the second substrate in a transparent plan view of the substrate.

Abstract: An electronic element mounting substrate includes a first substrate that has a first main surface, has a rectangular shape, and has a mounting portion for an electronic element on the first main surface, and a second substrate that is located on a second main surface opposite to the first main surface, is made of a carbon material, has a rectangular shape, has a third main surface facing the second main surface and a fourth main surface opposite to the third main surface, in which the third main surface or the fourth main surface has heat conduction in a longitudinal direction greater than heat conduction in a direction perpendicular to the longitudinal direction, and that has a recessed portion on the fourth main surface.

Abstract: A first substrate includes a first surface and a second surface opposite to the first surface. A second substrate includes a third surface and a fourth surface opposite to the third surface. A third substrate includes a fifth surface and a sixth surface opposite to the fifth surface. The first substrate is made of an insulator, and includes a mounting portion for mounting an electronic element at the first surface, and the mounting portion for mounting the electronic element is a rectangular shape. The third substrate is made of a carbon material, and the fifth surface is connected to at least the second surface at location overlapped with the mounting portion for mounting the electronic element in plan view. The third substrate has a larger heat conduction in a direction perpendicular to the longitudinal direction of the mounting portion than heat conduction in the longitudinal direction of the mounting portion in plan view.

Abstract: A substrate for mounting electronic element includes: a first substrate including a first surface and a second surface opposite to the first surface; a second substrate including a third surface and a fourth surface opposite to the third surface; and heat dissipation bodies each including a fifth surface and a sixth surface opposite to the fifth surface. The first substrate includes at least one mounting portion for at least one electronic element at the first surface. Heat conduction of the heat dissipation bodies in a direction perpendicular to a longitudinal direction of the at least one mounting portion and perpendicular to a direction along opposite sides of the second substrate is greater than heat conduction of the heat dissipation bodies in the longitudinal direction of the at least one mounting portion and in the direction along opposite sides of the second substrate in a transparent plan view of the substrate.

Abstract: 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.

Abstract: An electronic element mounting substrate includes a first substrate that has a first main surface, has a rectangular shape, and has a mounting portion for an electronic element on the first main surface, and a second substrate that is located on a second main surface opposite to the first main surface, is made of a carbon material, has a rectangular shape, has a third main surface facing the second main surface and a fourth main surface opposite to the third main surface, in which the third main surface or the fourth main surface has heat conduction in a longitudinal direction greater than heat conduction in a direction perpendicular to the longitudinal direction, and that has a recessed portion on the fourth main surface.

Abstract: A substrate for mounting electronic element includes: a first substrate including a first surface and a second surface opposed thereto, the first substrate being made of an insulating material; a second substrate made of a carbon material; at least one surface metal layer located on the first surface, including at least one mounting portion for at least one electronic element; and a bonding metal layer on the second surface. Heat conduction of the second substrate in a direction perpendicular to a longitudinal direction of the at least one mounting portion is greater than heat conduction of the second substrate in the longitudinal direction of the at least one mounting portion, and a width of the bonding metal layer is greater than or equal to a maximum width of the at least one surface metal layer in a direction perpendicular to the longitudinal direction of the at least one mounting portion.

Abstract: An electronic element mounting substrate includes a first substrate that has a first main surface, has a rectangular shape, and has a mounting portion for an electronic element on the first main surface, and a second substrate that is located on a second main surface opposite to the first main surface, is made of a carbon material, has a rectangular shape, has a third main surface facing the second main surface and a fourth main surface opposite to the third main surface, in which the third main surface or the fourth main surface has heat conduction in a longitudinal direction greater than heat conduction in a direction perpendicular to the longitudinal direction, and that has a recessed portion on the fourth main surface.

Abstract: An electronic element mounting substrate includes a first substrate including a first main surface and a mounting portion in a rectangular shape for mounting an electronic element, positioned on the first main surface and one end portion of the mounting portion in a longitudinal direction being positioned at an outer edge portion of the first main surface and a second substrate positioned on a second main surface opposite to the first main surface, formed of a carbon material, and including a third main surface facing the second main surface and a fourth main surface opposite to the third main surface. A thermal conduction of the mounting portion in a direction perpendicular to in a longitudinal direction is greater than a thermal conduction of the mounting portion in the longitudinal direction, in the third main surface or the fourth main surface, in plan view.

Abstract: An electronic element mounting substrate includes: a first substrate including a first principal face and a second principal face opposite to the first principal face; a second substrate including a third principal face and a fourth principal face opposite to the third principal face, the second substrate being made of a carbon material; and a plurality of via conductors that are arranged in the first substrate. The second substrate is located inside the first substrate in the plan view. In the plan view, the plurality of via conductors are arranged with the second substrate in between. In the plan view, heat conduction of the second substrate is greater in a direction perpendicular to a direction in which the plurality of via conductors are arranged with the second substrate in between than in the direction in which the plurality of via conductors are arranged with the second substrate in between.

Abstract: A substrate for mounting electronic element includes: a first substrate including a first surface and a second surface opposed thereto, the first substrate being made of an insulating material; a second substrate made of a carbon material; at least one surface metal layer located on the first surface, including at least one mounting portion for at least one electronic element; and a bonding metal layer on the second surface. Heat conduction of the second substrate in a direction perpendicular to a longitudinal direction of the at least one mounting portion is greater than heat conduction of the second substrate in the longitudinal direction of the at least one mounting portion, and a width of the bonding metal layer is greater than or equal to a maximum width of the at least one surface metal layer in a direction perpendicular to the longitudinal direction of the at least one mounting portion.

Abstract: 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.

Abstract: A first substrate includes a first surface and a second surface opposite to the first surface. A second substrate includes a third surface and a fourth surface opposite to the third surface. A third substrate includes a fifth surface and a sixth surface opposite to the fifth surface. The first substrate is made of an insulator, and includes a mounting portion for mounting an electronic element at the first surface, and the mounting portion for mounting the electronic element is a rectangular shape. The third substrate is made of a carbon material, and the fifth surface is connected to at least the second surface at location overlapped with the mounting portion for mounting the electronic element in plan view. The third substrate has a larger heat conduction in a direction perpendicular to the longitudinal direction of the mounting portion than heat conduction in the longitudinal direction of the mounting portion in plan view.

Abstract: A substrate for mounting electronic element includes: a first substrate including a first surface and a second surface opposite to the first surface; a second substrate including a third surface and a fourth surface opposite to the third surface; and heat dissipation bodies each including a fifth surface and a sixth surface opposite to the fifth surface. The first substrate includes at least one mounting portion for at least one electronic element at the first surface. Heat conduction of the heat dissipation bodies in a direction perpendicular to a longitudinal direction of the at least one mounting portion and perpendicular to a direction along opposite sides of the second substrate is greater than heat conduction of the heat dissipation bodies in the longitudinal direction of the at least one mounting portion and in the direction along opposite sides of the second substrate in a transparent plan view of the substrate.

Abstract: An electronic element mounting substrate includes a first substrate that has a first main surface, has a rectangular shape, and has a mounting portion for an electronic element on the first main surface, and a second substrate that is located on a second main surface opposite to the first main surface, is made of a carbon material, has a rectangular shape, has a third main surface facing the second main surface and a fourth main surface opposite to the third main surface, in which the third main surface or the fourth main surface has heat conduction in a longitudinal direction greater than heat conduction in a direction perpendicular to the longitudinal direction, and that has a recessed portion on the fourth main surface.

Abstract: An electronic element mounting substrate includes a substrate in a quadrangular shape, including a first main surface and a second main surface opposite to the first main surface, and heat dissipators arrayed and embedded in the substrate, made of a carbon material, and including a third main surface located on the first main surface side in a thickness direction and a fourth main surface opposite to the third main surface. The heat dissipators have, in a plan perspective view, greater heat conduction in a direction perpendicular to a direction in which the heat dissipators are arrayed than heat conduction in the direction in which the heat dissipators are arrayed.

Abstract: An electronic element mounting substrate includes a first substrate including a first main surface and a mounting portion in a rectangular shape for mounting an electronic element, positioned on the first main surface and one end portion of the mounting portion in a longitudinal direction being positioned at an outer edge portion of the first main surface and a second substrate positioned on a second main surface opposite to the first main surface, formed of a carbon material, and including a third main surface facing the second main surface and a fourth main surface opposite to the third main surface. A thermal conduction of the mounting portion in a direction perpendicular to in a longitudinal direction is greater than a thermal conduction of the mounting portion in the longitudinal direction, in the third main surface or the fourth main surface, in plan view.