Substrate connection structure, antenna substrate, and display device

Abstract

Provided are a substrate connection structure that facilitates adjustment of the impedance of a transmission line, an antenna substrate, and a display device. This substrate connection structure comprises a first substrate, a second substrate that partially faces the first substrate when viewed from the thickness direction of the first substrate, and a transmission line that spans the first substrate and the second substrate. The transmission line includes: a first transmission line on a first surface of the first substrate facing the second substrate; a second transmission line on a second surface of the second substrate facing the first substrate; a through-hole wire in a position not overlapping the second transmission line when viewed from the thickness direction of the first substrate; and a connection conductor disposed on the first surface and connected to the through-hole wire. The first transmission line extends from the connection conductor toward the second transmission line, and is connected to the second transmission line. In a second direction orthogonal to a first direction in which the first transmission line extends from the connection conductor toward the second transmission line when viewed from the thickness direction of the first substrate, the size of the first transmission line is smaller than the size of the connection conductor.

Description

Substrate connection structure, antenna substrate, display device

[0001] The present disclosure relates to a substrate connection structure, an antenna substrate, and a display device.

[0002] Patent Document 1 discloses a printed circuit board connection structure as one type of board connection structure. The printed circuit board connection structure disclosed in Patent Document 1 includes a plurality of printed circuit boards each having a connection pattern formed on its surface. At least one of the plurality of printed circuit boards is arranged so that its connection portions face each other. The facing connection patterns are connected by reflow-hardened solder. Patent Document 1 further discloses that in at least one of the printed circuit boards, a through hole is formed extending from the surface of the connection pattern facing the solder to the surface opposite the side on which the connection pattern is located.

[0003] JP 2008-60329 A

[0004] In the printed circuit board connection structure disclosed in Patent Document 1, a connection pattern is connected to a through hole. Generally, when connecting a transmission line such as a connection pattern to a through-hole wiring such as a through-hole, a connection conductor such as a land having a larger diameter than the through-hole wiring is used, taking into consideration misalignment between the through-hole wiring and the transmission line. However, when a connection conductor is used, the size of the transmission line must be set based on the size of the connection conductor. This limits the adjustment range of the size of the transmission line, which can be one of the factors that hinders adjustment of the impedance of the transmission line.

[0005] The present disclosure provides a substrate connection structure, an antenna substrate, and a display device that make it possible to easily adjust the impedance of a transmission line.

[0006] A substrate connection structure according to one aspect of the present disclosure includes a first substrate, a second substrate partially opposing the first substrate as viewed in a thickness direction of the first substrate, and a transmission line spanning the first and second substrates, wherein the transmission line includes a first transmission line on a first surface of the first substrate opposing the second substrate, a second transmission line on a second surface of the second substrate opposing the first substrate, a through-hole wiring exposed on the first surface at a position not overlapping with the second transmission line as viewed in the thickness direction of the first substrate, and a connection conductor on the first surface connected to the through-hole wiring, wherein the first transmission line extends from the connection conductor toward the second transmission line and is connected to the second transmission line, and a size of the first transmission line is smaller than a size of the connection conductor in a second direction orthogonal to a first direction in which the first transmission line extends from the connection conductor toward the second transmission line as viewed in the thickness direction of the first substrate.

[0007] An antenna substrate according to one aspect of the present disclosure includes the substrate connection structure described above and a radiation electrode on the second substrate, the radiation electrode being connected to the second transmission line.

[0008] A display device according to one aspect of the present disclosure includes the above-described antenna substrate and a display disposed on the second substrate opposite to the first substrate.

[0009] Aspects of the present disclosure allow for easier adjustment of the impedance of a transmission line.

[0010] 6A and 6B are cross-sectional views of a first wiring pattern of a first layer of a first substrate according to the second embodiment; a cross-sectional view of a second layer of a first substrate according to the second embodiment; a cross-sectional view of a third layer of a first substrate according to the second embodiment; a cross-sectional view of a second substrate of the antenna substrate according to the second embodiment; a cross-sectional view of an antenna substrate according to the third embodiment; a cross-sectional view of a second transmission line and a radiation electrode of an antenna substrate according to the fourth embodiment; a cross-sectional view of a display device according to the fifth embodiment; a plan view of a display device according to the fifth embodiment, with a portion thereof omitted; and a plan view of a second transmission line and a radiation electrode according to the fifth embodiment.

[0011] [1. Embodiments] Hereinafter, embodiments of the present disclosure will be described, with reference to the drawings where appropriate. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content (e.g., the shape, dimensions, and arrangement of each component). Positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings unless otherwise specified. Each figure described in the following embodiments is a schematic diagram, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios. Furthermore, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0012] In the following description, when it is necessary to distinguish between multiple components, prefixes such as "first" and "second" are added to the names of the components. However, when the components can be distinguished from each other by the symbols attached to them, the prefixes such as "first" and "second" may be omitted in consideration of readability of the text.

[0013] In the following description, when it is necessary to distinguish between multiple components, suffixes such as "-1" and "-2" are added to the symbols of the components. However, when it is not necessary to distinguish between multiple components, the suffixes "-1" and "-2" may be omitted to improve readability.

[0014] [1.1 First Embodiment] [1.1.1 Configuration] Fig. 1 is a perspective view of a substrate connection structure 1 according to the first embodiment. Fig. 2 is a plan view of the substrate connection structure 1. Fig. 3 is a cross-sectional view taken along line Y-Y in Fig. 2. Fig. 4 is a cross-sectional view taken along line XX in Fig. 2. In this embodiment and in the following, the XYZ Cartesian coordinate system shown in Figs. 1 to 4 will be used simply for the sake of simplicity.

[0015] The substrate connection structure 1 includes a first substrate 2 , a second substrate 3 , and a transmission line 4 .

[0016] The first substrate 2 has a thickness. In this embodiment, the thickness direction of the first substrate 2 is the Z direction. The first substrate 2 includes a dielectric layer 20. The dielectric layer 20 has a first surface 2a and a third surface 2b opposite the first surface 2a. The first surface 2a and the third surface 2b are both surfaces in the thickness direction of the first substrate 2. The first surface 2a and the third surface 2b are the main surfaces of the first substrate 2, and their normal directions coincide with the thickness direction of the first substrate 2. Therefore, the thickness direction of the first substrate 2 is sometimes referred to as the normal direction of the first substrate 2. The first substrate 2 has a first end 2c and a second end 2d that are opposite to each other in a first direction (X direction) that is perpendicular to the thickness direction. The first end 2c of the first substrate 2 faces the second substrate 3.

[0017] The second substrate 3 has a thickness. In this embodiment, the thickness direction of the second substrate 3 is the Z direction. That is, the thickness direction of the second substrate 3 coincides with the thickness direction of the first substrate 2. The second substrate 3 includes a dielectric layer 30. The dielectric layer 30 has a second surface 3a and a fourth surface 3b opposite the second surface 3a. The second surface 3a and the fourth surface 3b are both surfaces of the second substrate 3 in the thickness direction. The second substrate 3 has a first end 3c and a second end 3d that are opposite to each other in a first direction (X direction) that is perpendicular to the thickness direction. The first end 3c of the second substrate 3 faces the first substrate 2.

[0018] The first substrate 2 and the second substrate 3 are rectangular plates. The first substrate 2 and the second substrate 3 are, for example, dielectric substrates. Examples of dielectric substrates include a low-temperature co-fired ceramic (LTCC) multilayer substrate, a multilayer resin substrate formed by stacking multiple resin layers made of resin such as epoxy or polyimide, a multilayer resin substrate formed by stacking multiple resin layers made of liquid crystal polymer (LCP) having a lower dielectric constant, a multilayer resin substrate formed by stacking multiple resin layers made of fluorine-based resin, and a ceramic multilayer substrate other than LTCC.

[0019] As shown in FIG. 2 , the first substrate 2 and the second substrate 3 are arranged to partially overlap when viewed in the thickness direction of the first substrate 2. That is, the first substrate 2 and the second substrate 3 are not arranged so that one of the first substrate 2 and the second substrate 3 is enclosed within the other when viewed in the thickness direction of the first substrate 2. The first surface 2 a of the first substrate 2 and the second surface 3 a of the second substrate 3 partially face each other. In particular, the end of the first surface 2 a of the first substrate 2 on the first end 2 c side and the end of the second surface 3 a of the second substrate 3 on the first end 3 c side face each other. In this way, when viewed in the thickness direction of the first substrate 2, the ends of the first substrate 2 and the second substrate 3 face each other. This allows the distance between the opposite ends of the first substrate 2 and the second substrate 3 to be increased when viewed in the thickness direction of the first substrate 2, thereby increasing the line length of the transmission line 4.

[0020] The transmission line 4 spans the first substrate 2 and the second substrate 3. In this embodiment, the transmission line 4 is used to transmit a signal between an electronic component P1 mounted on the third surface 2b of the first substrate 2 and an electronic component P2 mounted on the second surface 3a of the second substrate 3. In this embodiment, the signal is a high-frequency signal. The electronic components P1 and P2 are not particularly limited, but examples thereof include an IC, a connector, a filter, an antenna element, etc. The transmission line 4 is a conductor pattern. Well-known materials can be used for the transmission line 4.

[0021] The transmission line 4 includes a first transmission line 4a, a second transmission line 4b, a through-hole wiring 4c, connection conductors 4d and 4e, a third transmission line 4f, and a connection layer 4g. As shown in Figures 1 to 3, the first transmission line 4a, the through-hole wiring 4c, the connection conductors 4d and 4e, and the third transmission line 4f are formed on the first substrate 2, and the second transmission line 4b is formed on the second substrate 3.

[0022] The second transmission line 4b is located on the second surface 3a of the second substrate 3, facing the first substrate 2. The second transmission line 4b extends from the first end 3c of the second substrate 3 toward the second end 3d. The second transmission line 4b is linear. The end of the second transmission line 4b on the first end 3c side of the second substrate 3 is used as an electrode for connection to the first transmission line 4a. The end of the second transmission line 4b on the first end 3c side is connected to the first transmission line 4a, and the end of the second transmission line 4b on the second end 3d side is connected to the electronic component P2.

[0023] The first transmission line 4a is located on the first surface 2a of the first substrate 2, which faces the second substrate 3. The third transmission line 4f is located on the third surface 2b of the first substrate 2, which is opposite to the second substrate 3. The through-hole wiring 4c and the connecting conductors 4d and 4e connect the first transmission line 4a and the third transmission line 4f, which are located on the first surface 2a and the third surface 2b, which are different from each other.

[0024] The through-hole wiring 4c penetrates the first substrate 2 so as to be exposed on the first surface 2a and the third surface 2b of the first substrate 2. The through-hole wiring 4c is a so-called through-hole wiring.

[0025] The connection conductor 4d is located on the first surface 2a of the first substrate 2 and is connected to the through-hole wiring 4c. The connection conductor 4e is located on the third surface 2b of the first substrate 2 and is connected to the through-hole wiring 4c. The connection conductors 4d and 4e are so-called lands. More specifically, the connection conductors 4d and 4e are located so as to overlap with the through-hole wiring 4c when viewed in the thickness direction of the first substrate 2. In this embodiment, the diameters of the connection conductors 4d and 4e are larger than the diameter of the through-hole wiring 4c.

[0026] The first transmission line 4a extends from the connecting conductor 4d toward the first end 2c of the first substrate 2. In other words, the first transmission line 4a extends from the connecting conductor 4d toward the second transmission line 4b. The first transmission line 4a is linear. The end of the first transmission line 4a on the first end 2c side of the first substrate 2 is used as an electrode for connection to the second transmission line 4b. The end of the first transmission line 4a on the first end 2c side is connected to the second transmission line 4b, and the end of the first transmission line 4a on the second end 2d side is connected to the connecting conductor 4d.

[0027] The third transmission line 4f extends from the connecting conductor 4d toward the second end 2d of the first substrate 2. The third transmission line 4f is linear. The end of the third transmission line 4f on the first end 2c side is connected to the connecting conductor 4e, and the end of the third transmission line 4f on the second end 2d side is connected to the electronic component P1.

[0028] 3 and 4 , the connection layer 4g is located between the first transmission line 4a and the second transmission line 4b and connects the first transmission line 4a and the second transmission line 4b. The connection layer 4g is formed of, for example, solder. The material of the connection layer 4g is not limited to solder, and may be any material that is conductive and can connect the first transmission line 4a and the second transmission line 4b. For example, the connection layer 4g may be formed of an anisotropic conductive film.

[0029] 2 , in the transmission line 4, the through-hole wiring 4c is located so as not to overlap the second transmission line 4b when viewed in the thickness direction of the first substrate 2. In particular, the through-hole wiring 4c is located so as not to overlap the second substrate 3 when viewed in the thickness direction of the first substrate 2. Therefore, in order to connect the through-hole wiring 4c to the second transmission line 4b, the first transmission line 4a is located on the first surface 2a of the first substrate 2 that faces the second substrate 3.

[0030] Here, the direction in which the first transmission line 4a extends from the connecting conductor 4d toward the second transmission line 4b is defined as the first direction. The first direction is the X direction. The direction perpendicular to the first direction when viewed from the thickness direction of the first substrate 2 is defined as the second direction. The second direction is the Y direction. In this embodiment, as shown in FIGS. 1 and 4 , the size W1 of the first transmission line 4a in the second direction is smaller than the size W2 of the connecting conductor 4d. Furthermore, in this embodiment, the size W1 of the first transmission line 4a in the second direction is smaller than the size W3 of the through-hole wiring 4c. The size W1 of the first transmission line 4a in the second direction can be considered to be the width of the first transmission line 4a. The size W2 of the connecting conductor 4d in the second direction can be considered to be the diameter of the connecting conductor 4d. The size W3 of the through-hole wiring 4c in the second direction can be considered to be the diameter of the through-hole wiring 4c.

[0031] 1, in the second direction, the size W4 of the second transmission line 4b is set to be the same as the size W1 of the first transmission line 4a. The size W4 of the second transmission line 4b in the second direction can be said to be the width of the second transmission line 4b.

[0032] In this embodiment, the second transmission line 4b is connected not to the through-hole wiring 4c but to the first transmission line 4a connected to the through-hole wiring 4c. Therefore, the size W4 of the second transmission line 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d, rather than the size required for connection to the through-hole wiring 4c, i.e., the size W2 of the connecting conductor 4d. This allows the size W4 of the second transmission line 4b to be reduced. This means that the adjustment range for the size W4 of the second transmission line 4b is increased. In other words, when adjusting the size W4 of the second transmission line 4b in consideration of the characteristics of the transmission line 4, the size W4 of the second transmission line 4b is not limited to be equal to or larger than the size W2 of the connecting conductor 4d, and can be smaller than the size W2 of the connecting conductor 4d. This facilitates adjustment of the impedance of the transmission line 4.

[0033] [1.1.2 Effects, etc.] The substrate connection structure 1 described above includes a first substrate 2, a second substrate 3 partially opposing the first substrate 2 when viewed in the thickness direction of the first substrate 2, and a transmission line 4 spanning the first substrate 2 and the second substrate 3. The transmission line 4 includes a first transmission line 4a on a first surface 2a of the first substrate 2 opposing the second substrate 3, a second transmission line 4b on a second surface 3a of the second substrate 3 opposing the first substrate 2, a through-hole wiring 4c located in a position that does not overlap with the second transmission line 4b when viewed in the thickness direction of the first substrate 2, and a connection conductor 4d on the first surface 2a that is connected to the through-hole wiring 4c. The first transmission line 4a extends from the connection conductor 4d toward the second transmission line 4b and is connected to the second transmission line 4b. The size W1 of the first transmission line 4a is smaller than the size W2 of the connecting conductor 4d in a second direction (Y direction) that is perpendicular to the first direction (X direction) in which the first transmission line 4a extends from the connecting conductor 4d toward the second transmission line 4b when viewed from the thickness direction (Z direction) of the first substrate 2. This configuration makes it possible to easily adjust the impedance of the transmission line 4.

[0034] In the substrate connection structure 1, the size W1 of the first transmission line 4a in the second direction is smaller than the size W3 of the through-hole wiring 4c. This configuration makes it possible to further facilitate adjustment of the impedance of the transmission line 4.

[0035] In the substrate connection structure 1, the ends of the first substrate 2 and the second substrate 3 face each other when viewed in the thickness direction of the first substrate 2. This configuration allows the line length of the transmission line 4 to be increased.

[0036] In the substrate connection structure 1, the through-hole wiring 4c is located at a position that does not overlap with the second substrate 3 when viewed in the thickness direction of the first substrate 2. This configuration makes it possible to reduce the influence of interference between the through-hole wiring 4c and the second substrate 3.

[0037] [1.2 Second Embodiment] [1.2.1 Configuration] Fig. 5 is a perspective view of an antenna substrate 10A according to a second embodiment. Fig. 6 is a plan view of the antenna substrate 10A. Fig. 7 is a cross-sectional view taken along line Y-Y in Fig. 6. Fig. 8 is a cross-sectional view taken along line XX in Fig. 6.

[0038] The antenna substrate 10A includes a substrate connection structure 1A, a plurality of radiation electrodes 11-1 to 11-4, and a processing circuit 12.

[0039] The substrate connection structure 1A includes a first substrate 2A, a second substrate 3A, and a transmission line 4A.

[0040] The first substrate 2A includes a dielectric layer 20A and a first ground electrode 5 .

[0041] The dielectric layer 20A has a multi-layer structure, and a first ground electrode 5 is disposed between the first surface 2a and the third surface 2b. Hereinafter, the wiring pattern formed on the third surface 2b will be referred to as the wiring pattern of the first layer, the wiring pattern formed between the first surface 2a and the third surface 2b will be referred to as the wiring pattern of the second layer, and the wiring pattern formed on the first surface 2a will be referred to as the wiring pattern of the third layer.

[0042] The dielectric layer 20A has a shape in which the width of a first portion 2e on the first end 2c side is wider than the width of a second portion 2f on the second end 2d side.

[0043] The second substrate 3A includes a dielectric layer 30 and a second ground electrode 6. The second ground electrode 6 is on the fourth surface 3b of the dielectric layer 30. The second ground electrode 6 is on the opposite side of the second transmission line 4b from the first substrate 2A. The second ground electrode 6 is a conductor pattern. The second ground electrode 6 is planar. The second ground electrode 6 is substantially rectangular when viewed in the thickness direction (Z direction) of the second substrate 3A.

[0044] In this embodiment, the dielectric constant of the second substrate 3A is lower than the dielectric constant of the first substrate 2A. The thickness of the second substrate 3A is greater than the thickness of the first substrate 2A.

[0045] 6, in this embodiment as well, the first substrate 2A and the second substrate 3A are arranged so as to partially overlap when viewed in the thickness direction of the first substrate 2A. The first surface 2a of the first substrate 2A and the second surface 3a of the second substrate 3A partially face each other. In particular, the end of the first surface 2a of the first substrate 2A on the first end 2c side and the end of the second surface 3a of the second substrate 3A on the first end 3c side face each other. Therefore, in this embodiment as well, the ends of the first substrate 2A and the second substrate 3A face each other when viewed in the thickness direction of the first substrate 2A.

[0046] See FIG. 6. The radiation electrodes 11-1 to 11-4 are conductor patterns formed on the second surface 3a of the second substrate 3A. The radiation electrode 11 is planar. In this embodiment, the predetermined direction along the polarization direction of the radio waves emitted from the radiation electrode 11 is set to the X direction. The radiation electrode 11 is substantially rectangular when viewed from the thickness direction (Z direction) of the second substrate 3A. The radiation electrodes 11-1 to 11-4 are aligned in a direction (Y direction) perpendicular to the direction (X direction) between the first end 3c and the second end 3d of the second substrate 3A when viewed from the thickness direction (Z direction) of the second substrate 3A.

[0047] The shapes of the radiation electrodes 11-1 to 11-4 are determined according to the frequency band used for wireless communication, such as a frequency band around 28 GHz and a frequency band around 39 GHz.

[0048] In this embodiment, the second ground electrode 6 includes a ground conductor that, together with the radiation electrodes 11-1 to 11-4, constitutes a patch antenna. In the radiation electrode 11, the boundary between the radiation electrode 11 and the second transmission line 4b acts as a feed point. In this embodiment, the predetermined direction along the straight line connecting the feed point and the center of the radiation electrode 11 coincides with the X direction.

[0049] The processing circuit 12 is mounted on the third surface 2b of the first substrate 2A. The processing circuit 12 includes, for example, an IC. An example of the processing circuit 12 is a SiP (System in Package). The processing circuit 12 executes processing for wireless communication via, for example, the radiating electrodes 11-1 to 11-4. The processing circuit 12 can output high-frequency signals to the radiating electrodes 11-1 to 11-4 via the transmission line 4A. The processing circuit 12 can receive high-frequency signals from the radiating electrodes 11-1 to 11-4 via the transmission line 4A. The processing circuit 12 may be mounted together with a connector. In this case, the processing circuit 12 can transmit signals via the connector.

[0050] The transmission line 4A spans the first substrate 2A and the second substrate 3A. In this embodiment, the transmission line 4A is used to transmit high-frequency signals between the processing circuit 12 mounted on the third surface 2b of the first substrate 2A and the plurality of radiation electrodes 11 arranged on the second surface 3a of the second substrate 3A.

[0051] The transmission line 4A includes a plurality of first transmission lines 4a, a plurality of second transmission lines 4b, a plurality of through-hole wirings 4c, a plurality of connecting conductors 4d, a plurality of connecting conductors 4e, a plurality of third transmission lines 4f, and a plurality of connecting layers 4g.

[0052] The transmission line 4A will be further described with reference to FIGS. 9 to 12 in addition to FIGS. 5 to 8. FIG. 9 is a plan view showing the wiring pattern of the first layer of the first substrate 2A. FIG. 10 is a plan view showing the wiring pattern of the second layer of the first substrate 2A. FIG. 11 is a plan view showing the wiring pattern of the third layer of the first substrate 2A. FIG. 12 is a plan view of the second substrate 3A.

[0053] 12, the second transmission lines 4b-1 to 4b-4 are located on the second surface 3a of the second substrate 3A, facing the first substrate 2A. The second transmission lines 4b-1 to 4b-4 extend from the first end 3c to the second end 3d of the second substrate 3A. When viewed from the thickness direction (Z direction) of the second substrate 3A, the second transmission lines 4b-1 to 4b-4 are aligned in a direction (Y direction) perpendicular to the direction (X direction) between the first end 3c and the second end 3d of the second substrate 3A, and are parallel to each other. The ends of the second transmission lines 4b-1 to 4b-4 on the first end 3c side of the second substrate 3 are used as electrodes for connection to the first transmission lines 4a-1 to 4a-4. The second transmission lines 4b-1 to 4b-4 are connected to the first transmission lines 4a-1 to 4a-4 at their ends on the first end 3c side, and connected to the radiation electrodes 11-1 to 11-4 at their ends on the second end 3d side.

[0054] 5, the first transmission line 4a is located on the first surface 2a of the first substrate 2A facing the second substrate 3A, and the third transmission line 4f is located on the third surface 2b of the first substrate 2A opposite the second substrate 3A. The through-hole wiring 4c and the connecting conductors 4d and 4e connect the first transmission line 4a and the third transmission line 4f, which are located on the first surface 2a and the third surface 2b, which are different from each other.

[0055] 9 to 11, the through-hole wirings 4c-1 to 4c-4 penetrate the first substrate 2A so as to be exposed on the first surface 2a and the third surface 2b of the first substrate 2A, respectively. The through-hole wirings 4c-2 and 4c-3 are located at a first portion 2e on the first end 2c side of the first substrate 2A, and the through-hole wirings 4c-1 and 4c-4 are located at a second portion 2f on the second end 2d side of the first substrate 2A. In this embodiment, the through-hole wirings 4c-2 and 4c-3 are located on the opposite side of the processing circuit 12 from the through-hole wirings 4c-1 and 4c-4. The through-hole wirings 4c-1 and 4c-4 are aligned in the Y direction, and the through-hole wirings 4c-2 and 4c-3 are aligned in the Y direction.

[0056] 11, the connecting conductors 4d-1 to 4d-4 are located on the first surface 2a of the first substrate 2A and are connected to the through-hole wirings 4c-1 to 4c-4, respectively. Referring to Fig. 9, the connecting conductors 4e-1 to 4e-4 are located on the third surface 2b of the first substrate 2A and are connected to the through-hole wirings 4c-1 to 4c-4, respectively. More specifically, the connecting conductors 4d-1 to 4d-4 and 4e-1 to 4e-4 are positioned so as to overlap with the through-hole wirings 4c-1 to 4c-4 when viewed in the thickness direction of the first substrate 2A.

[0057] 11, the first transmission lines 4a-1 to 4a-4 extend from the connecting conductors 4d-1 to 4d-4 toward the first end 2c of the first substrate 2A (the second transmission line 4b side). The ends of the first transmission lines 4a-1 to 4a-4 toward the first end 2c of the first substrate 2A are used as electrodes for connection to the second transmission lines 4b-1 to 4b-4. The first transmission lines 4a-1 to 4a-4 are connected at their ends toward the first end 2c to the second transmission lines 4b-1 to 4b-4 and connected at their ends toward the second end 2d to the connecting conductors 4d-1 to 4d-4.

[0058] The first transmission line 4a-2 and the first transmission line 4a-3 are linear along the X direction. Referring to FIGS. 6 and 7, the lengths of the first transmission line 4a-2 and the first transmission line 4a-3 are set to satisfy D<L. Here, L is the size of the radiation electrodes 11-2 and 11-3 in a predetermined direction along the polarization direction of the radio waves radiated from the radiation electrodes 11-2 and 11-3. In this embodiment, L can also be said to be the size of the radiation electrodes 11-2 and 11-3 in a predetermined direction along a straight line connecting the feed points and the centers of the radiation electrodes 11-2 and 11-3. D is the distance in the predetermined direction from the centers of the through-hole wirings 4c-2 and 4c-3 to the ends of the first transmission lines 4a-2 and 4a-3 on the side of the second transmission lines 4b-2 and 4b-3. When D=L, radio wave radiation occurs in the first transmission lines 4a-2 and 4a-3, that is, the first transmission lines 4a-2 and 4a-3 may function as antennas instead of the radiation electrodes 11-2 and 11-3. By satisfying D<L, the possibility of unwanted radio wave radiation occurring in the first transmission lines 4a-2 and 4a-3 can be reduced. This enables the antenna efficiency of the antenna substrate 10A to be improved.

[0059] The first transmission line 4a-1 and the first transmission line 4a-4 have a bent shape. The first transmission line 4a-1 and the first transmission line 4a-4 include first to fifth lines 41-1 to 45-1 and 41-4 to 45-4. The first lines 41-1 and 41-4 extend in the X direction from the connecting conductors 4d-1 to 4d-4. The second lines 42-1 and 42-4 extend in directions away from each other from the ends of the first lines 41-1 and 41-4 on the first end 2c side. The third lines 43-1 and 43-4 extend in the X direction from the ends of the second lines 42-1 and 42-4 on the first end 2c side. The third lines 43-1 and 43-4 are aligned in a straight line with the first transmission line 4a-2 and the first transmission line 4a-3, respectively, in the X direction. The fourth lines 44-1 and 44-4 extend in directions away from each other from the ends of the third lines 43-1 and 43-4 on the first end 2c side. The fifth lines 45-1 and 45-4 extend in the X direction from the ends of the fourth lines 44-1 and 44-4 on the first end 2c side. The fifth lines 45-1 and 45-4 are located on both sides of the first transmission lines 4a-2 and 4a-3 in the Y direction. Therefore, the fifth line 45-1, the first transmission line 4a-2, the first transmission line 4a-3, and the fifth line 45-4 are aligned in the Y direction.

[0060] 9, the third transmission lines 4f-1 and 4f-4 extend from the connecting conductors 4e-1 and 4e-4, respectively, toward the first end 2c of the first substrate 2A (the second transmission line 4b side). The third transmission lines 4f-1 and 4f-4 are linear and extend along the X direction. The third transmission lines 4f-1 and 4f-4 are connected to the connecting conductors 4e-1 and 4e-4, respectively, at their ends on the first end 2c side, and are connected to the processing circuit 12 at their ends on the second end 2d side.

[0061] The third transmission lines 4f-2 and 4f-3 extend from the connecting conductors 4e-2 and 4e-3, respectively, toward the second end 2d of the first substrate 2A (the opposite side from the second transmission line 4b). The third transmission lines 4f-2 and 4f-3 have a bent shape. The third transmission lines 4f-2 and 4f-3 include sixth to eighth lines 46-2 to 48-2 and 46-3 to 48-3. The sixth lines 46-3 and 46-2 extend along the X direction from the connecting conductors 4e-2 to 4e-3. The sixth lines 46-2 and 46-3 partially overlap with the third lines 43-1 and 43-4 when viewed in the thickness direction of the first substrate 2A. The seventh lines 47-2 and 47-3 extend toward each other from the ends of the sixth lines 46-2 and 46-3 on the second end 2d side. The seventh lines 47-2 and 47-3 overlap with the second lines 42-1 and 42-4 when viewed from the thickness direction of the first substrate 2A. The eighth lines 48-2 and 48-3 extend in the X direction from the ends of the seventh lines 47-2 and 47-3 on the second end 2d side and are connected to the processing circuit 12. The eighth lines 48-2 and 48-3 partially overlap with the first lines 41-1 and 41-4 when viewed from the thickness direction of the first substrate 2A. The eighth lines 48-2 and 48-3 are aligned in a straight line with the third transmission lines 4f-1 and 4f-4, respectively, in the X direction.

[0062] Referring to FIG. 6, the connection layers 4g-1 to 4g-4 are located between the first transmission lines 4a-1 to 4a-4 and the second transmission lines 4b-1 to 4b-4, respectively, and couple the first transmission lines 4a-1 to 4a-4 and the second transmission lines 4b-1 to 4b-4, respectively.

[0063] 7 and 8, the third transmission line 4f-2 is a parallel line that is spaced apart from the first first transmission line 4a-1 of the plurality of first transmission lines 4a-1 to 4a-4 in the thickness direction of the first substrate 2A and is connected to a second first transmission line 4a-2, which is different from the first first transmission line 4a-1, of the plurality of first transmission lines 4a-1 to 4a-4, via a through-hole wiring 4c-2. In particular, the third transmission line 4f-2 partially overlaps the first transmission line 4a-1 in the thickness direction of the first substrate 2A. The first first transmission line 4a-1 and the second first transmission line 4a-2 are connected to two adjacent second transmission lines 4b-1, 4b-2 of the plurality of second transmission lines 4b-1 to 4b-4.

[0064] Similarly, the third transmission line 4f-3 is a parallel line that is spaced apart from the first first transmission line 4a-4 of the plurality of first transmission lines 4a-1 to 4a-4 in the thickness direction of the first substrate 2A and is connected to a second first transmission line 4a-3, which is different from the first first transmission line 4a-4, of the plurality of first transmission lines 4a-1 to 4a-4, via a through-hole wiring 4c-3. In particular, the third transmission line 4f-3 partially overlaps the first transmission line 4a-4 in the thickness direction of the first substrate 2A. The first first transmission line 4a-4 and the second first transmission line 4a-3 are connected to two adjacent second transmission lines 4b-3 and 4b-4 of the plurality of second transmission lines 4b-1 to 4b-4.

[0065] The first substrate 2A includes a first ground electrode 5, and at least a portion of the first ground electrode 5 is located between the third transmission line 4f-2 and the first transmission line 4a-1, and between the third transmission line 4f-3 and the first transmission line 4a-4. That is, when viewed in the thickness direction of the first substrate 2A, at least a portion of the first ground electrode 5 overlaps with at least a portion of the first transmission line 4a-1, and at least a portion of the third transmission line 4f-2, and at least a portion of the first ground electrode 5 overlaps with at least a portion of the first transmission line 4a-4, and at least a portion of the third transmission line 4f-3. This improves isolation between the third transmission line 4f-2 and the first transmission line 4a-1 and between the third transmission line 4f-3 and the first transmission line 4a-4. In this way, in the substrate connection structure 1A, the first first transmission lines (first transmission lines 4a-1, 4a-4) and the parallel lines (third transmission lines 4f-2, 4f-3) connected to the second first transmission lines (4a-2, 4a-3) can be arranged separately in the thickness direction of the first substrate 2A. This allows the multiple first transmission lines 4a-1 to 4a-4 to be arranged efficiently by utilizing the thickness direction of the first substrate 2A, and the area over which the multiple first transmission lines 4a-1 to 4a-4 are arranged on the first surface 2a can be narrowed. Therefore, the area required for arranging the multiple first transmission lines 4a-1 to 4a-4 on the first substrate 2A can be reduced.

[0066] Furthermore, the first first transmission line 4a-1 and the second first transmission line 4a-2 are connected to two adjacent second transmission lines 4b-1 and 4b-2 among the plurality of second transmission lines 4b-1 to 4b-4, and the first first transmission line 4a-4 and the second first transmission line 4a-3 are connected to two adjacent second transmission lines 4b-3 and 4b-4 among the plurality of second transmission lines 4b-1 to 4b-4. Therefore, the second transmission lines 4b-1 to 4b-4 can be arranged on the same plane (second surface 3a) while reducing the area required for arranging the plurality of first transmission lines 4a-1 to 4a-4 on the first substrate 2A.

[0067] The first ground electrode 5 will be further described with reference to FIG. 10 . The first ground electrode 5 is located on the dielectric layer 20A of the first substrate 2A, between the first surface 2a and the third surface 2b. The first ground electrode 5 is disposed between the third transmission line 4f-2 and the first transmission line 4a-1, and between the third transmission line 4f-3 and the first transmission line 4a-4. The first ground electrode 5 has voids 5a-1 to 5a-4 so as not to contact the through-hole wirings 4c-1 to 4c-4. Referring to FIG. 11 , the first ground electrode 5 has a side 5b on the first end 2c side of the first substrate 2A. The side 5b of the first ground electrode 5 is spaced a predetermined distance from the first end 2c. The predetermined distance is set so that the first ground electrode 5 does not overlap the second substrate 3A when viewed in the thickness direction of the first substrate 2A.

[0068] The first ground electrode 5 can affect the impedance of the first transmission lines 4a-2 and 4a-3. Since the first transmission lines 4a-2 and 4a-3 have the same structure, the following description will refer to the first transmission line 4a-2 for simplicity.

[0069] The impedance of the first transmission line 4a-2 increases as the capacitance between the first transmission line 4a-2 and the first ground electrode 5 decreases. If the capacitance between the first transmission line 4a-2 and the first ground electrode 5 is C1, then C1 = ε1 * S1 / d1. ε1 is the dielectric constant of the first substrate 2A. The dielectric constant of the first substrate 2A is the dielectric constant of the dielectric layer 20A of the first substrate 2A. S1 is the area of ​​the overlapping portion between the first transmission line 4a-2 and the first ground electrode 5 when viewed in the thickness direction of the first substrate 2A. d1 is the distance between the first transmission line 4a-2 and the first ground electrode 5 in the thickness direction of the first substrate 2A, as shown in FIG. 7 .

[0070] The impedance of the first transmission line 4a-2 is closer to the impedance of the second transmission line 4b-2 to which the first transmission line 4a-2 is connected, which reduces reflections and improves transmission efficiency. The impedance of the second transmission line 4b-2 is affected by the capacitance between the second transmission line 4b-2 and the second ground electrode 6, and decreases as this capacitance increases. If the capacitance between the second transmission line 4b-2 and the second ground electrode 6 is C2, then C2 is expressed as C2 = ε2 * S2 / d2. ε2 is the dielectric constant of the second substrate 3A. The dielectric constant of the second substrate 3A is the dielectric constant of the dielectric layer 30 of the second substrate 3A. S2 is the area of ​​the overlapping portion between the second transmission line 4b-2 and the second ground electrode 6 when viewed in the thickness direction of the second substrate 3A. d2 is the distance between the second transmission line 4b-2 and the second ground electrode 6 in the thickness direction of the second substrate 3A, as shown in FIG. 7 .

[0071] In this embodiment, the dielectric constant ε1 of the first substrate 2A is higher than the dielectric constant ε2 of the second substrate 3A, and the distance d1 is shorter than the distance d2. In this case, C1 tends to be larger than C2. Therefore, S1 is made smaller to reduce C1. For this reason, in this embodiment, the first ground electrode 5 is configured so as not to overlap with the second substrate 3A when viewed from the thickness direction of the first substrate 2A. This reduces the difference in impedance between the first transmission line 4a-2 and the second transmission line 4b-2, enabling an improvement in the transmission efficiency of the transmission line 4A.

[0072] 6, in the substrate connection structure 1A of the antenna substrate 10A described above, the through-hole wirings 4c-1 to 4c-4 are positioned so as not to overlap with the second transmission lines 4b-1 to 4b-4 when viewed in the thickness direction of the first substrate 2A. In particular, the through-hole wirings 4c-1 to 4c-4 are positioned so as not to overlap with the second substrate 3A when viewed in the thickness direction of the first substrate 2A. Therefore, in order to connect the through-hole wirings 4c-1 to 4c-4 to the second transmission lines 4b-1 to 4b-4, respectively, the first transmission lines 4a-1 to 4a-4 are located on the first surface 2a of the first substrate 2A that faces the second substrate 3A.

[0073] Referring to FIG. 11 , in the second direction (Y direction), the size W1 of the first transmission line 4a-2 is smaller than the size W2 of the connecting conductor 4d-2. Furthermore, in the second direction, the size W1 of the first transmission line 4a-2 is smaller than the size W3 of the through-hole wiring 4c-2. This also applies to the first transmission lines 4a-1, 4a-3, and 4a-4. Here, the first transmission line 4a-1 has a bent shape but includes a linear first line 41-1 extending from the connecting conductor 4d-1. The size W2 of the first transmission line 4a-1 in the second direction (Y direction) only needs to be the size of the first line 41-1 in the second direction (Y direction), and the sizes of the second to fifth lines 42-1 to 45-1 in the second direction are set based on the size of the first line 41-1 in the second direction. This also applies to the first transmission line 4a-4.

[0074] The second transmission line 4b is connected not to the through-hole wiring 4c but to the first transmission line 4a which is connected to the through-hole wiring 4c. Therefore, the size W4 (see FIG. 12) of the second transmission line 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d, rather than the size required as a connecting conductor for connection to the through-hole wiring 4c, i.e., the size W2 of the connecting conductor 4d. Therefore, the substrate connection structure 1A makes it possible to easily adjust the impedance of the transmission line 4A.

[0075] In the substrate connection structure 1A, the multiple second transmission lines 4b are aligned in the second direction and parallel to one another. As described above, the size W4 of the second transmission lines 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d. Therefore, even if the spacing between the multiple second transmission lines 4b is the same, the size W4 of the second transmission lines 4b can be reduced, thereby increasing the gap between adjacent second transmission lines 4b. Therefore, the substrate connection structure 1A makes it possible to easily adjust the impedance of the transmission line 4A, even when multiple second transmission lines 4b are included.

[0076] 5, transmission line 4A includes a ground structure 7. Referring to both Figures 11 and 12, ground structure 7 includes ground lines 7a-1 to 7a-5, 7b-1 to 7b-5, through-hole wiring 7c-1 to 7c-6, and connection lines 7d and 7e.

[0077] 11, the ground lines 7a-1 to 7a-5 and the connection line 7d are located on the first surface 2a of the first substrate 2A. The ground lines 7a-1 to 7a-5 are linear and extend in the X direction, and are aligned in the Y direction. The ground lines 7a-1 to 7a-5 are arranged so that two of the ground lines 7a-1 to 7a-5 are located on either side of one of the first transmission lines 4a-1 to 4a-4 in the second direction (Y direction). The first transmission line 4a-1 is located between the ground lines 7a-1 and 7a-2. The first transmission line 4a-2 is located between the ground lines 7a-2 and 7a-3. The first transmission line 4a-3 is located between the ground lines 7a-3 and 7a-4. The first transmission line 4a-4 is located between the ground lines 7a-4 and 7a-5.

[0078] The connection line 7d connects the ends of the ground lines 7a-2 to 7a-4 that are on the second end 2d side of the first substrate 2A. The connection line 7d is located between the first transmission lines 4a-1 and 4a-2 and between the first transmission lines 4a-3 and 4a-4 in the X direction, and improves isolation therebetween.

[0079] The through-hole wirings 7c-1 to 7c-6 are located on the first substrate 2A. The through-hole wirings 7c-1 to 7c-6 are via-hole wirings that penetrate the portion of the dielectric layer 20A between the first surface 2a and the first ground electrode 5 so as to connect the ground lines 7a-1 to 7a-5 and the connection line 7d to the first ground electrode 5.

[0080] 12, the ground lines 7b-1 to 7b-5 and the connection line 7e are located on the second surface 3a of the second substrate 3A. The ground lines 7b-1 to 7b-5 are linear and extend in the X direction, and are aligned in the Y direction. The ground lines 7b-1 to 7b-5 are arranged so that two of the ground lines 7b-1 to 7b-5 are located on either side of one of the second transmission lines 4b-1 to 4b-4 in the second direction (Y direction). The second transmission line 4b-1 and the radiation electrode 11-1 are located between the ground lines 7b-1 and 7b-2. The second transmission line 4b-2 and the radiation electrode 11-2 are located between the ground lines 7b-2 and 7b-3. The second transmission line 4b-3 and the radiation electrode 11-3 are located between the ground lines 7b-3 and 7b-4. The second transmission line 4b-4 is located between the ground lines 7b-4 and 7b-5.

[0081] The connection line 7e connects the ends of the ground lines 7b-1 to 7b-5 that are on the second end 3d side of the second substrate 3A. The connection line 7e and the ground lines 7b-1 and 7b-5 surround the second transmission lines 4b-1 to 4b-4 and the radiation electrodes 11-1 to 11-4.

[0082] In the grounding structure 7, the ends of the grounding lines 7a-1 to 7a-5 on the first end 2c side of the first substrate 2A are connected to the ends of the grounding lines 7b-1 to 7b-5 on the first end 3c side of the second substrate 3A by a conductive connecting material such as solder.

[0083] The transmission line 4A includes a ground structure 7, which includes ground lines 7a on both sides of the first transmission line 4a and ground lines 7b on both sides of the second transmission line 4b in the second direction. The first transmission line 4a and the ground lines 7a on both sides thereof, and the second transmission line 4b and the ground lines 7b on both sides thereof, each constitute a coplanar waveguide. This configuration using coplanar waveguides suppresses unwanted radiation and improves resistance to disturbances compared to microstrip lines. In other words, this configuration enables reduced unwanted radiation and improved resistance to disturbances.

[0084] As described above, the size W1 of the first transmission line 4a is smaller than the size W2 of the connecting conductor 4d. Therefore, even if the spacing between the multiple first transmission lines 4a is the same, the size W1 of the first transmission lines 4a can be reduced, thereby increasing the gap between adjacent first transmission lines 4a. Therefore, the width of the ground line 7a (the size of the ground line 7a in the second direction) can be increased without changing the distance between the ground line 7a and the first transmission line 4a. This makes it possible to improve the isolation characteristics between adjacent first transmission lines 4a.

[0085] Furthermore, the size W4 of the second transmission line 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d. Therefore, even if the spacing between the multiple second transmission lines 4b is the same, the size W4 of the second transmission line 4b can be reduced, thereby increasing the gap between adjacent second transmission lines 4b. Therefore, the width of the ground line 7b (the size of the ground line 7b in the second direction) can be increased without changing the distance between the ground line 7b and the second transmission line 4b. This improves the isolation characteristics between adjacent second transmission lines 4b.

[0086] [1.2.2 Effects, etc.] In the board connection structure 1A described above, the transmission line 4A includes a plurality of second transmission lines 4b. Two or more of the plurality of second transmission lines 4b are parallel to one another. This configuration allows the size W4 of the second transmission lines 4b to be reduced, thereby increasing the gap between adjacent second transmission lines 4b. Therefore, the board connection structure 1A makes it possible to easily adjust the impedance of the transmission line 4A even when there are a plurality of second transmission lines 4b.

[0087] In the substrate connection structure 1A, the transmission line 4A includes a plurality of first transmission lines 4a-1 to 4a-4. The transmission line 4A includes a third transmission line 4f-2, which is a parallel line spaced apart from a first first transmission line 4a-1 of the plurality of first transmission lines 4a-1 to 4a-4 in the thickness direction of the first substrate 2A and connected via a through-hole wiring 4c-2 to a second first transmission line 4a-2, which is different from the first first transmission line 4a-1, of the plurality of first transmission lines 4a-1 to 4a-4. The first substrate 2A includes a first ground electrode 5. At least a portion of the first ground electrode 5 is located between the first first transmission line (4a-1) and the parallel line (4f-2) in the thickness direction of the first substrate 2A. This configuration can reduce the area required for arranging the plurality of first transmission lines 4a-1 to 4a-4 on the first substrate 2A.

[0088] In the substrate connection structure 1A, the transmission line 4A includes a plurality of first transmission lines 4a-1 to 4a-4. The transmission line 4A includes a third transmission line 4f-2, which is a parallel line spaced apart from a first first transmission line 4a-1 of the plurality of first transmission lines 4a-1 to 4a-4 in the thickness direction of the first substrate 2A and connected via a through-hole wiring 4c-2 to a second first transmission line 4a-2, which is different from the first first transmission line 4a-1, of the plurality of first transmission lines 4a-1 to 4a-4. The first substrate 2A includes a first ground electrode 5. When viewed in the thickness direction of the first substrate 2A, at least a portion of the first ground electrode 5, at least a portion of the first first transmission line (first transmission line 4a-1), and at least a portion of the parallel line (third transmission line 4f-2) overlap. This configuration can reduce the area required for arranging the plurality of first transmission lines 4a-1 to 4a-4 on the first substrate 2A.

[0089] In the substrate connection structure 1A, the transmission line 4A includes a plurality of second transmission lines 4b-1 to 4b-4. The first first transmission line 4a-1 and the second first transmission line 4a-2 are connected to two adjacent second transmission lines 4b-1 and 4b-2 of the plurality of second transmission lines 4b-1 to 4b-4, and the first first transmission line 4a-4 and the second first transmission line 4a-3 are connected to two adjacent second transmission lines 4b-3 and 4b-4 of the plurality of second transmission lines 4b-1 to 4b-4. Therefore, the second transmission lines 4b-1 to 4b-4 can be arranged on the same plane (second surface 3a) while reducing the area required for arranging the plurality of first transmission lines 4a-1 to 4a-4 on the first substrate 2A.

[0090] In the substrate connection structure 1A, the dielectric constant of the first substrate 2A is higher than the dielectric constant of the second substrate 3A. The distance d1 between the first transmission lines 4a-2, 4a-3 and the first ground electrode 5 in the thickness direction of the first substrate 2A is shorter than the distance d2 between the second transmission lines 4b-2, 4b-3 and the second ground electrode 6 located on the opposite side of the first substrate 2A from the second transmission lines 4b-2, 4b-3 in the thickness direction of the second substrate 3A. When viewed in the thickness direction of the first substrate 2A, the first ground electrode 5 does not overlap the second substrate 3A. This configuration can reduce the difference in impedance between the first transmission lines 4a-2, 4a-3 and the second transmission lines 4b-2, 4b-3, thereby improving the transmission efficiency of the transmission line 4A.

[0091] In the substrate connection structure 1A, the transmission line 4A includes ground lines 7a on both sides of the first transmission line 4a and ground lines 7b on both sides of the second transmission line 4b in the second direction. The first transmission line 4a and the ground lines 7a on both sides thereof, and the second transmission line 4b and the ground lines 7b on both sides thereof, each constitute a coplanar line. By configuring the transmission line using coplanar lines in this way, it is possible to suppress unwanted radiation and improve resistance to disturbances compared to microstrip lines. In other words, this configuration enables the reduction of unwanted radiation and the improvement of resistance to disturbances.

[0092] The antenna substrate 10A described above includes the substrate connection structure 1A and the radiation electrode 11 that is on the second substrate 3A and is connected to the second transmission line 4b. This configuration makes it possible to easily adjust the impedance of the transmission line 4A.

[0093] The antenna substrate 10A described above satisfies D<L. L is the size of the radiation electrodes 11-2 and 11-3 in a predetermined direction along the polarization direction of the radio waves radiated from the radiation electrodes 11-2 and 11-3. D is the distance in the predetermined direction from the center of the through-hole wiring 4c-2 and 4c-3 to the end of the first transmission line 4a-2 and 4a-3 on the second transmission line 4b-2 and 4b-3 side. This configuration can reduce the possibility of unwanted radio wave radiation from the first transmission line 4a-2 and the first transmission line 4a-3, and can improve the antenna efficiency of the antenna substrate 10A.

[0094] From another perspective, the antenna substrate 10A described above satisfies D<L. In this case, L is the size of the radiation electrodes 11-2 and 11-3 in a predetermined direction along a straight line connecting the feed points and the centers of the radiation electrodes 11-2 and 11-3. D is the distance in the predetermined direction from the centers of the through-hole wirings 4c-2 and 4c-3 to the ends of the first transmission lines 4a-2 and 4a-3 on the second transmission lines 4b-2 and 4b-3 side. This configuration can reduce the possibility of unwanted radio wave radiation from the first transmission lines 4a-2 and 4a-3, and enables improvement of the antenna efficiency of the antenna substrate 10A.

[0095] 13 is a cross-sectional view of an antenna substrate 10B according to embodiment 3. The antenna substrate 10B includes a substrate connection structure 1B, a plurality of radiation electrodes 11-1 to 11-4, and a processing circuit 12.

[0096] The substrate connection structure 1B includes a first substrate 2B, a second substrate 3B, and a transmission line 4A.

[0097] The second substrate 3B differs from the second substrate 3A in dielectric constant and thickness. The dielectric constant of the second substrate 3B is higher than the dielectric constant of the first substrate 2B. The thickness of the second substrate 3B is thinner than the thickness of the first substrate 2B.

[0098] The first substrate 2B includes a dielectric layer 20A and a first ground electrode 5B.

[0099] Fig. 14 is a plan view showing the wiring pattern of the second layer of the first substrate 2B. The side 5b of the first ground electrode 5B on the first end 2c side of the first substrate 2A is closer to the first end 2c than the first ground electrode 5. In Fig. 14, the side 5b of the first ground electrode 5B is shown by a solid line, and the side 5b of the first ground electrode 5 is shown by a dashed line. In the first ground electrode 5B, the predetermined distance between the side 5b and the first end 2c is set so that at least a portion of the first ground electrode 5B overlaps with the second substrate 3B when viewed from the thickness direction of the first substrate 2A.

[0100] In this embodiment, the dielectric constant ε1 of the first substrate 2B is lower than the dielectric constant ε2 of the second substrate 3B, and the distance d1 is longer than the distance d2. In this case, C1 tends to be smaller than C2. Therefore, S1 is increased to increase C1. For this reason, in this embodiment, at least a portion of the first ground electrode 5B is configured to overlap with the second substrate 3B when viewed from the thickness direction of the first substrate 2B. This reduces the difference in impedance between the first transmission line 4a-2 and the second transmission line 4b-2, enabling an improvement in the transmission efficiency of the transmission line 4A.

[0101] [1.3.2 Effects, etc.] In the substrate connection structure 1B described above, the dielectric constant of the first substrate 2B is lower than the dielectric constant of the second substrate 3B. The distance d1 between the first transmission lines 4a-2, 4a-3 and the first ground electrode 5B in the thickness direction of the first substrate 2B is longer than the distance d2 between the second transmission lines 4b-2, 4b-3 and the second ground electrode 6 located on the opposite side of the first substrate 2B from the second transmission lines 4b-2, 4b-3 in the thickness direction of the second substrate 3B. When viewed in the thickness direction of the first substrate 2B, at least a portion of the first ground electrode 5B overlaps with the second substrate 3B. This configuration can reduce the difference in impedance between the first transmission lines 4a-2, 4a-3 and the second transmission lines 4b-2, 4b-3, thereby improving the transmission efficiency of the transmission line 4A.

[0102] 15 is a plan view of the second transmission line 4b and the radiation electrode 11 of the antenna substrate 10C according to the fourth embodiment. Like the antenna substrate 10B according to the third embodiment, the antenna substrate 10C according to the fourth embodiment includes a substrate connection structure 1B, a plurality of radiation electrodes 11-1 to 11-4, and a processing circuit 12, and the substrate connection structure 1B includes a first substrate 2B, a second substrate 3B, and a transmission line 4A. The antenna substrate 10C differs from the antenna substrate 10B in that the second transmission line 4b, the radiation electrode 11, the second ground electrode 6, and the ground structure 7 each have a mesh structure 8.

[0103] The mesh structure 8 includes a plurality of first linear conductors 8a and a plurality of second linear conductors 8b intersecting the plurality of first linear conductors 8a. The plurality of first linear conductors 8a are parallel to one another. The plurality of first linear conductors 8a extend in a third direction. The plurality of second linear conductors 8b are parallel to one another. The plurality of second linear conductors 8b extend in a fourth direction different from the third direction. In this embodiment, the third direction corresponds to the length direction (X direction) of the second transmission line 4b. The fourth direction does not correspond to the length direction (X direction) of the second transmission line 4b, but corresponds to a direction (Y direction) perpendicular to the third direction.

[0104] In the mesh structure 8, adjacent first linear conductors 8a and adjacent second linear conductors 8b define one opening 8c. The multiple openings 8c are regularly arranged in the third and fourth directions. The presence of the multiple openings 8c reduces the visibility of the mesh structure 8 itself. In other words, the mesh structure 8 becomes difficult to see with the naked eye. As an example, the width of the first linear conductors 8a and the width of the second linear conductors 8b are 1 μm, and the spacing between the first linear conductors 8a and the spacing between the second linear conductors 8b are 100 μm. The ratio of the total area of ​​the multiple openings 8c to the area of ​​the region where the mesh structure 8 is arranged is preferably 80% or more. The mesh structure 8 preferably has a visible light transmittance of 80% or more.

[0105] The second transmission line 4b has a mesh structure 8. Therefore, the visibility of the second transmission line 4b can be reduced. In the mesh structure 8, the third direction corresponds to the length direction (X direction) of the second transmission line 4b. Therefore, compared to a case where the third direction does not correspond to the length direction of the second transmission line 4b, the path of the current flowing through the second transmission line 4b can be shortened, the current loss in the second transmission line 4b can be reduced, and the antenna gain can be improved.

[0106] When the second transmission line 4b has the mesh structure 8, the electric field is more likely to propagate to the outside in the fourth direction (Y direction), which may result in a decrease in isolation characteristics compared to when the second transmission line 4b does not have the mesh structure 8. However, as described above, the size W4 of the second transmission line 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d. Here, if the distance between the multiple second transmission lines 4b is d and the gap between adjacent second transmission lines 4b is I, then d = W4 + I. Therefore, if the size W4 of the second transmission line 4b can be reduced, the gap I between adjacent second transmission lines 4b can be increased without changing the distance d between the multiple second transmission lines 4b. Therefore, even if the isolation characteristics are reduced due to the mesh structure 8, the overall isolation characteristics may be improved. On the other hand, since the spacing d between the multiple second transmission lines 4b can be narrowed without changing the gap I between adjacent second transmission lines 4b, the area required to implement the multiple second transmission lines 4b can be reduced while maintaining the isolation characteristics, and it may be possible to reduce the board area of ​​the second board 3B.

[0107] The radiation electrode 11 has a mesh structure 8. Therefore, the visibility of the radiation electrode 11 can be reduced. The radiation electrode 11 has the same mesh structure 8 as the second transmission line 4b. Here, as long as the third direction and the fourth direction of the mesh structure 8 of the second transmission line 4b and the mesh structure 8 of the radiation electrode 11 match, it can be said that the second transmission line 4b and the radiation electrode 11 have the same mesh structure 8. In other words, the width of the first linear conductors 8a, the width of the second linear conductors 8b, the spacing between the first linear conductors 8a, and the spacing between the second linear conductors 8b of the mesh structure 8 of the second transmission line 4b and the mesh structure 8 of the radiation electrode 11 do not need to match. When the second transmission line 4b and the radiation electrode 11 have the same mesh structure 8, current flows more efficiently between the second transmission line 4b and the radiation electrode 11 than when the second transmission line 4b and the radiation electrode 11 have different mesh structures, thereby improving the antenna gain.

[0108] The second ground electrode 6 has a mesh structure 8. Therefore, the visibility of the second ground electrode 6 can be reduced.

[0109] The ground structure 7 has a mesh structure 8. This reduces the visibility of the ground structure 7. In the ground structure 7, it is sufficient that the ground line 7b and the connection line 7e arranged on the second substrate 3B have the mesh structure 8.

[0110] When the second transmission line 4b and the ground structure 7 have the mesh structure 8, the electric field is more likely to propagate to the outside in the fourth direction (Y direction), which may result in a decrease in isolation characteristics compared to when the mesh structure 8 is not included. However, as described above, the size W4 of the second transmission line 4b can be set based on the size W1 of the first transmission line 4a, which is smaller than the size W2 of the connecting conductor 4d. Therefore, the gap I between adjacent second transmission lines 4b can be increased without changing the spacing d between the multiple second transmission lines 4b. Therefore, the width of the ground line 7b (the size of the ground line 7b in the second direction) can be increased without changing the distance between the ground line 7b and the second transmission line 4b. This may enable an improvement in overall isolation characteristics even when the mesh structure 8 reduces isolation characteristics. On the other hand, since the spacing d between the multiple second transmission lines 4b can be narrowed without changing the gap I between adjacent second transmission lines 4b, the area required to implement the multiple second transmission lines 4b can be reduced while maintaining the isolation characteristics, and it may be possible to reduce the board area of ​​the second board 3B.

[0111] The antenna substrate 10C differs from the antenna substrate 10B according to the third embodiment in that the dielectric layer 30 of the second substrate 3B is transparent. The dielectric layer 30 may be formed of, for example, well-known glass or transparent resin. Examples of transparent resins include organic insulating materials such as polyester resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, polycarbonate resins, polyimide resins, polyolefin resins such as cycloolefin polymers, and cellulose resin materials such as triacetyl cellulose.

[0112] The antenna substrate 10C can reduce the visibility of each of the second substrate 3B, the second transmission line 4b, the radiation electrode 11, the second ground electrode 6, and the ground structure 7. This makes it possible to arrange the second substrate 3B, for example, overlapping a display or the like that is viewed by humans, thereby improving the degree of freedom in arranging the antenna substrate 10C.

[0113] [1.4.2 Effects, etc.] In the substrate connection structure 1B of the antenna substrate 10C described above, the second transmission line 4b has a mesh structure 8. This configuration can reduce the visibility of the second transmission line 4b.

[0114] In the substrate connection structure 1B of the antenna substrate 10C, the second substrate 3B includes a second ground electrode 6 located on the opposite side of the second transmission line 4b from the first substrate 2B. At least one of the second transmission line 4b and the second ground electrode 6 has a mesh structure 8. This configuration can reduce the visibility of at least one of the second transmission line 4b and the second ground electrode 6.

[0115] In the antenna substrate 10C, the second transmission line 4b and the radiation electrode 11 have a mesh structure 8. This configuration can reduce the visibility of the second transmission line 4b and the radiation electrode 11.

[0116] In the antenna substrate 10C, the second transmission line 4b and the radiation electrode 11 have the same mesh structure 8. This configuration enables an improvement in antenna gain compared to when the second transmission line 4b and the radiation electrode 11 have different mesh structures.

[0117] In the antenna substrate 10C, the mesh structure 8 includes a plurality of first linear conductors 8a extending in a third direction and parallel to one another, and a plurality of second linear conductors 8b extending in a fourth direction different from the third direction and intersecting the plurality of first linear conductors 8a. The third direction corresponds to the length direction of the second transmission line 4b, and the fourth direction does not correspond to the length direction of the second transmission line 4b. This configuration enables an improvement in antenna gain compared to a case where the third direction does not correspond to the length direction of the second transmission line 4b.

[0118] [1.5 Fifth Embodiment] [1.5.1 Configuration] Fig. 16 is a cross-sectional view of a display device 100D according to a fifth embodiment. Fig. 17 is a plan view of the display device 100D, with a portion thereof omitted.

[0119] The display device 100D includes an antenna substrate 10D and a display 13.

[0120] The display 13 includes a display element 14 and an input device 15 .

[0121] The display element 14 is a liquid crystal display, an organic EL display, etc. As shown in Fig. 17 , the display element 14 has a plurality of pixels 14a arranged in a fifth direction and a sixth direction intersecting the fifth direction. In the present embodiment, the fifth direction is the X direction, and the sixth direction is the Y direction.

[0122] The input device 15 is a transparent touch pad. As shown in Fig. 16, the input device 15 is disposed in front of the display element 14, and together with the display element 14, forms a touch panel.

[0123] 16 and 17, an antenna substrate 10D includes a substrate connection structure 1D, a plurality of radiation electrodes 11-1 to 11-4, and a processing circuit 12. The substrate connection structure 1D includes a first substrate 2B, a second substrate 3D, and a transmission line 4B.

[0124] In the second substrate 3D, the dielectric layer 30 is transparent. The dielectric layer 30 may be formed of, for example, well-known glass or transparent resin. The second substrate 3D does not include a second ground electrode 6. The antenna substrate 10D is mounted on the display 13 with the fourth surface 3b of the second substrate 2D facing the input device 15 of the display 13. In this configuration, the input device 15 acts as the second ground electrode.

[0125] 18 is a plan view of the second transmission line 4b and the radiation electrode 11 of the antenna substrate 10D. In the antenna substrate 10D, the second transmission line 4b, the radiation electrode 11, and the ground structure 7 have a mesh structure 9.

[0126] The mesh structure 9 includes a plurality of first linear conductors 9a and a plurality of second linear conductors 9b intersecting the first linear conductors 9a. The first linear conductors 9a are parallel to one another. The first linear conductors 9a extend in a third direction. The second linear conductors 9b are parallel to one another. The second linear conductors 9b extend in a fourth direction different from the third direction. In this embodiment, the third direction and the fourth direction are different from the length direction (X direction) of the second transmission line 4b, the fifth direction (X direction), or the sixth direction (Y direction). For example, the third direction is inclined at 30° with respect to the length direction (X direction) of the second transmission line 4b, and the fourth direction is inclined at 60° with respect to the third direction. As a result, compared to the mesh structure 8, the mesh structure 9 becomes less noticeable relative to the pixels 14a of the display 13, and the visibility of the mesh structure 9 decreases in the display device 100D as a whole.

[0127] In the mesh structure 9, adjacent first linear conductors 9a and adjacent second linear conductors 9b define one opening 9c. The multiple openings 9c are regularly arranged in the third and fourth directions. The presence of the multiple openings 9c reduces the visibility of the mesh structure 9 itself. In other words, the mesh structure 9 becomes difficult to see with the naked eye. As an example, the width of the first linear conductor 9a and the width of the second linear conductor 9b are 1 μm, and the spacing between the first linear conductors 9a and the spacing between the second linear conductors 9b are 100 μm. The ratio of the total area of ​​the multiple openings 9c to the area of ​​the region where the mesh structure 9 is arranged is preferably 80% or more. The mesh structure 9 preferably has a visible light transmittance of 80% or more.

[0128] [1.5.2 Effects, etc.] The display device 100D described above includes the antenna substrate 10D and the display 13 arranged on the second substrate 3D on the opposite side to the first substrate 2A. This configuration makes it possible to easily adjust the impedance of the transmission line 4.

[0129] In the display device 100D, the second transmission line 4b and the radiation electrode 11 have the same mesh structure 9. The mesh structure 9 includes a plurality of first linear conductors 9a extending parallel to one another in a third direction and a plurality of second linear conductors 9b extending parallel to one another in a fourth direction different from the third direction and intersecting the first linear conductors 9a. The display 13 includes a plurality of pixels 14a arranged in a fifth direction and a sixth direction intersecting the fifth direction. Each of the third and fourth directions is different from the longitudinal direction of the second transmission line 4b, the fifth direction, or the sixth direction. This configuration reduces the visibility of the second transmission line 4b and the radiation electrode 11 compared to when the third or fourth direction coincides with the longitudinal direction of the second transmission line 4b, the fifth direction, or the sixth direction. Furthermore, this configuration improves the antenna gain compared to when the second transmission line 4b and the radiation electrode 11 have different mesh structures.

[0130] [2. Modifications] The embodiments of the present disclosure are not limited to the above-described embodiments. The above-described embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above-described embodiments are listed below. The modifications described below can be applied in appropriate combinations.

[0131] In the following, reference will be made to the symbols used in embodiment 1, even though they are applicable to any of the above embodiments 1 to 5. However, this is merely to simplify the description and is not intended to exclude application to embodiments 2 to 5.

[0132] In one modified example, the shapes and dimensions of the first substrate 2 and the second substrate 3 may be changed as appropriate. For example, the first substrate 2 may include multiple dielectric layers, and the third transmission line 4f may be located on a different dielectric layer rather than on the third surface 2b. In this case, the through-hole wiring 4c may be configured as a via-hole wiring rather than a through-hole wiring.

[0133] In one modified example, the configuration of the transmission line 4 is not limited to the above example. In the transmission line 4, the number, arrangement, and shape of each of the first transmission line 4 a, the second transmission line 4 b, the through-hole wiring 4 c, the connecting conductors 4 d and 4 e, and the third transmission line 4 f may be changed as appropriate.

[0134] In one modified example, the transmission line 4 may include a plurality of second transmission lines 4 b. In this case, all of the plurality of second transmission lines 4 b may be parallel to one another, or two or more of the plurality of second transmission lines 4 b may be parallel to one another.

[0135] In one modified example, the shapes and dimensions of the first ground electrode 5 and the second ground electrode 6 may be changed as appropriate. Furthermore, the positions of the first ground electrode 5 and the second ground electrode 6 may be changed. The second ground electrode 6 may be located within the dielectric layer 30 of the second substrate 3. In this case, the distance d2 is not the distance between the second surface 3a and the fourth surface 3b of the dielectric layer 30 of the second substrate 3 (i.e., the thickness of the second substrate 3), but is the distance from the second surface 3a to the second ground electrode 6 in the dielectric layer 30. Furthermore, the first ground electrode 5 and the second ground electrode 6 may be omitted.

[0136] In one variation, the ground structure 7 may include only one of the ground lines 7a-1 to 7a-5 or the ground lines 7b-1 to 7b-5. That is, the transmission line 4 may include ground lines on both sides of at least one of the first transmission line 4a or the second transmission line 4b in the second direction. Also, the transmission line 4 may not have the ground structure 7.

[0137] In one modified example, it is not necessary for all of the second transmission line 4 b, the second ground electrode 6, the ground structure 7, and the radiation electrode 11 to have the mesh structure 8 or the mesh structure 9. Any one of the second transmission line 4 b, the second ground electrode 6, the ground structure 7, and the radiation electrode 11 may have the mesh structure 8 or the mesh structure 9.

[0138] In one modified example, the frequency band of the wireless communication using the radiating electrode 11 is not particularly limited. For example, the frequency band may be selected from well-known frequency bands such as the frequency band for UWB wireless communication, the frequency band for Bluetooth (registered trademark), the frequency band for Wi-Fi wireless communication, the mid-band of the 2G (second generation mobile communication) standard, the low-band of the 4G (fourth generation mobile communication) standard, and the low-band of the 5G (fifth generation mobile communication) standard. The 2G standard is, for example, the GSM (registered trademark) standard (GSM: Global System for Mobile Communications). The 4G standard is, for example, the 3GPP (registered trademark) LTE standard (LTE: Long Term Evolution). The 5G standard is, for example, 5G NR (New Radio). The frequency band may be selected from frequency bands used in various communication standards such as wireless LAN, specified low-power radio, and short-range wireless communication.

[0139] [3. Aspects] As is clear from the above-described embodiment and modifications, the present disclosure includes the following aspects.

[0140] a second substrate partially opposing the first substrate as viewed in a thickness direction of the first substrate; and a transmission line spanning the first substrate and the second substrate, wherein the transmission line includes: a first transmission line on a first surface of the first substrate opposing the second substrate; a second transmission line on a second surface of the second substrate opposing the first substrate; through-hole wiring located at a position not overlapping with the second transmission line as viewed in the thickness direction of the first substrate; and a connection conductor located on the first surface and connected to the through-hole wiring, wherein the first transmission line extends from the connection conductor toward the second transmission line and is connected to the second transmission line, and a size of the first transmission line is smaller than a size of the connection conductor in a second direction orthogonal to a first direction in which the first transmission line extends from the connection conductor toward the second transmission line as viewed in the thickness direction of the first substrate.

[0141] [Aspect 2] The substrate connection structure of Aspect 1, wherein the size of the first transmission line in the second direction is smaller than the size of the through-hole wiring.

[0142] [Aspect 3] The substrate connection structure of Aspect 1 or 2, wherein ends of the first substrate and the second substrate face each other when viewed in the thickness direction of the first substrate.

[0143] [Aspect 4] The substrate connection structure according to any one of Aspects 1 to 3, wherein the through-hole wiring is located at a position that does not overlap the second substrate when viewed in a thickness direction of the first substrate.

[0144] [Aspect 5] The substrate connection structure of any one of Aspects 1 to 4, wherein the transmission line includes a plurality of the second transmission lines, and two or more of the plurality of second transmission lines are parallel to each other.

[0145] Aspect 6 is a substrate connection structure according to any one of Aspects 1 to 5, wherein the transmission line includes a plurality of the first transmission lines, the transmission line including a parallel line that is spaced apart from a first first transmission line of the plurality of first transmission lines in a thickness direction of the first substrate and is connected via the through-hole wiring to a second first transmission line of the plurality of first transmission lines that is different from the first first transmission line, and the first substrate includes a first ground electrode, and at least a portion of the first ground electrode is located between the first first transmission line and the parallel line in the thickness direction of the first substrate.

[0146] Aspect 7 is a substrate connection structure according to any one of Aspects 1 to 5, wherein the transmission line includes a plurality of the first transmission lines, the transmission line including a parallel line that is spaced apart from a first first transmission line of the plurality of first transmission lines in a thickness direction of the first substrate and is connected via the through-hole wiring to a second first transmission line of the plurality of first transmission lines that is different from the first first transmission line, the first substrate includes a first ground electrode, and at least a portion of the first ground electrode, at least a portion of the first first transmission line, and at least a portion of the parallel line overlap when viewed in the thickness direction of the first substrate.

[0147] [Aspect 8] The substrate connection structure of Aspect 6 or 7, wherein the transmission line includes a plurality of the second transmission lines, and the first first transmission line and the second first transmission line are connected to two adjacent second transmission lines of the plurality of second transmission lines.

[0148] [Aspect 9] The substrate connection structure of any one of Aspects 6 to 8, wherein the dielectric constant of the first substrate is higher than the dielectric constant of the second substrate, the distance between the first transmission line and the first ground electrode in the thickness direction of the first substrate is shorter than the distance between the second transmission line and a second ground electrode on the opposite side of the first substrate with respect to the second transmission line in the thickness direction of the second substrate, and the first ground electrode does not overlap with the second substrate when viewed in the thickness direction of the first substrate.

[0149] [Aspect 10] The substrate connection structure of any one of Aspects 6 to 8, wherein the dielectric constant of the first substrate is lower than the dielectric constant of the second substrate, the distance between the first transmission line and the first ground electrode in the thickness direction of the first substrate is longer than the distance between the second transmission line and a second ground electrode on the opposite side of the first substrate with respect to the second transmission line in the thickness direction of the second substrate, and at least a portion of the first ground electrode overlaps with the second substrate as viewed in the thickness direction of the first substrate.

[0150] [Aspect 11] The substrate connection structure according to any one of Aspects 1 to 10, wherein the second transmission line has a mesh structure.

[0151] [Aspect 12] The substrate connection structure of any one of Aspects 1 to 10, wherein the second substrate includes a second ground electrode on the opposite side of the second transmission line from the first substrate, and at least one of the second transmission line and the second ground electrode has a mesh structure.

[0152] [Aspect 13] The substrate connection structure according to any one of Aspects 1 to 12, wherein the transmission line includes ground lines on both sides of at least one of the first transmission line and the second transmission line in the second direction.

[0153] [Aspect 14] An antenna substrate comprising: the substrate connection structure according to any one of Aspects 1 to 13; and a radiation electrode on the second substrate, the radiation electrode being connected to the second transmission line.

[0154] [Aspect 15] The antenna substrate of Aspect 14, wherein D<L is satisfied, L is the size of the radiation electrode in a predetermined direction along the polarization direction of the radio wave radiated from the radiation electrode, and D is the distance in the predetermined direction from the center of the through-hole wiring to the end of the first transmission line on the second transmission line side.

[0155] [Aspect 16] The antenna substrate of Aspect 14, wherein D<L is satisfied, L is the size of the radiation electrode in a predetermined direction along a line connecting the feed point and the center of the radiation electrode, and D is the distance in the predetermined direction from the center of the through-hole wiring to the end of the first transmission line on the side of the second transmission line.

[0156] [Aspect 17] The antenna substrate according to any one of Aspects 14 to 16, wherein the second transmission line and the radiation electrode have a mesh structure.

[0157] [Aspect 18] The antenna substrate of Aspect 17, wherein the second transmission line and the radiation electrode have the same mesh structure.

[0158] [Aspect 19] The antenna substrate of Aspect 18, wherein the mesh structure includes a plurality of first linear conductors extending in a third direction and parallel to one another, and a plurality of second linear conductors extending in a fourth direction different from the third direction and intersecting the plurality of first linear conductors, wherein the third direction corresponds to the length direction of the second transmission line, and the fourth direction does not correspond to the length direction of the second transmission line.

[0159] [Aspect 20] A display device comprising: the antenna substrate according to any one of Aspects 14 to 16; and a display disposed on the second substrate opposite to the first substrate.

[0160] Aspect 21 is a display device according to Aspect 20, wherein the second transmission line and the radiation electrode have the same mesh structure, the mesh structure comprising: a plurality of first linear conductors extending in a third direction and parallel to one another; and a plurality of second linear conductors extending in a fourth direction different from the third direction and intersecting with the plurality of first linear conductors, the display having a plurality of pixels aligned in a fifth direction and a sixth direction intersecting with the fifth direction, each of the third direction and the fourth direction being different from the length direction of the second transmission line, the fifth direction, or the sixth direction.

[0161] The second to thirteenth, fifteenth to nineteenth and twenty-first aspects are optional elements and are not essential.

[0162] The present disclosure is applicable to a substrate connection structure and an antenna substrate. Specifically, the present disclosure is applicable to a substrate connection structure having a transmission line spanning between substrates, and an antenna substrate having the substrate connection structure.

[0163] 1, 1A, 1B Board connection structure 2, 2A, 2B 1st board 2a 1st surface 2b 3rd surface 2c 1st end 3, 3A, 3B 2nd board 3a 2nd surface 3b 4th surface 4, 4A Transmission line 4a, 4a-1 to 4a-4 1st transmission line 4b, 4b-1 to 4b-4 2nd transmission line 4c, 4c-1 to 4c-4 Through-hole wiring 4d, 4d-1 to 4d-4 Connection conductor 4f, 4f-1, 4f-4 Third transmission line 4f-2, 4f-3 Third transmission line (parallel running line) 5, 5B First grounding electrode 6 Second grounding electrode (grounding conductor) 7 Grounding structure 7a-1 to 7a-5 Grounding line 7b-1 to 7b-5 Ground line 8 Mesh structure 8a First linear conductor 8b Second linear conductor 9 Mesh structure 9a First linear conductor 9b Second linear conductor 10A, 10B, 10C, 10D Antenna substrate 11, 11-1 to 11-4 Radiation electrodes 13 Display 14a Pixel 15 Input device (second ground electrode) 100D Display device

Claims

1. A substrate connection structure comprising: a first substrate; a second substrate partially opposing the first substrate as viewed in a thickness direction of the first substrate; and a transmission line spanning the first substrate and the second substrate, wherein the transmission line includes: a first transmission line on a first surface of the first substrate opposing the second substrate; a second transmission line on a second surface of the second substrate opposing the first substrate; a through hole wiring located in a position not overlapping with the second transmission line as viewed in the thickness direction of the first substrate; and a connection conductor on the first surface and connected to the through hole wiring, wherein the first transmission line extends from the connection conductor to the second transmission line and is connected to the second transmission line, and a size of the first transmission line is smaller than a size of the connection conductor in a second direction perpendicular to a first direction in which the first transmission line extends from the connection conductor to the second transmission line as viewed in the thickness direction of the first substrate.

2. The substrate connection structure according to claim 1, wherein the size of the first transmission line in the second direction is smaller than the size of the through-hole wiring.

3. The board connection structure according to claim 1 or 2, wherein ends of the first board and the second board face each other when viewed in the thickness direction of the first board.

4. A substrate connection structure according to any one of claims 1 to 3, wherein the through-hole wiring is located so as not to overlap with the second substrate when viewed in the thickness direction of the first substrate.

5. The substrate connection structure according to any one of claims 1 to 4, wherein the transmission line includes a plurality of the second transmission lines, and two or more of the plurality of second transmission lines are parallel to each other.

6. A substrate connection structure according to any one of claims 1 to 5, wherein the transmission line includes a plurality of the first transmission lines, the transmission line including a parallel line that is spaced apart from a first first transmission line of the plurality of first transmission lines in a thickness direction of the first substrate and is connected via the through-hole wiring to a second first transmission line of the plurality of first transmission lines that is different from the first first transmission line, the first substrate is provided with a first ground electrode, and at least a portion of the first ground electrode is located between the first first transmission line and the parallel line in the thickness direction of the first substrate.

7. A substrate connection structure according to any one of claims 1 to 5, wherein the transmission line includes a plurality of the first transmission lines, the transmission line including a parallel line that is spaced apart from a first first transmission line of the plurality of first transmission lines in a thickness direction of the first substrate and is connected via the through-hole wiring to a second first transmission line of the plurality of first transmission lines that is different from the first first transmission line, the first substrate is provided with a first ground electrode, and at least a portion of the first ground electrode, at least a portion of the first first transmission line, and at least a portion of the parallel line overlap when viewed in the thickness direction of the first substrate.

8. The substrate connection structure according to claim 6 or 7, wherein the transmission line includes a plurality of the second transmission lines, and the first first transmission line and the second first transmission line are connected to two adjacent second transmission lines among the plurality of second transmission lines.

9. A substrate connection structure according to any one of claims 6 to 8, wherein the dielectric constant of the first substrate is higher than the dielectric constant of the second substrate, the distance between the first transmission line and the first ground electrode in the thickness direction of the first substrate is shorter than the distance between the second transmission line and a second ground electrode on the opposite side of the first substrate with respect to the second transmission line in the thickness direction of the second substrate, and the first ground electrode does not overlap the second substrate as viewed in the thickness direction of the first substrate.

10. A substrate connection structure according to any one of claims 6 to 8, wherein the dielectric constant of the first substrate is lower than the dielectric constant of the second substrate, the distance between the first transmission line and the first ground electrode in the thickness direction of the first substrate is longer than the distance between the second transmission line and a second ground electrode on the opposite side of the first substrate with respect to the second transmission line in the thickness direction of the second substrate, and at least a portion of the first ground electrode overlaps with the second substrate as viewed in the thickness direction of the first substrate.

11. The substrate connection structure according to any one of claims 1 to 10, wherein the second transmission line has a mesh structure.

12. A substrate connection structure according to any one of claims 1 to 10, wherein the second substrate is provided with a second ground electrode on the opposite side of the second transmission line to the first substrate, and at least one of the second transmission line and the second ground electrode has a mesh structure.

13. A substrate connection structure according to any one of claims 1 to 12, wherein the transmission line includes a ground line on both sides of at least one of the first transmission line or the second transmission line in the second direction.

14. An antenna substrate comprising: a substrate connection structure according to any one of claims 1 to 13; and a radiation electrode on the second substrate, the radiation electrode being connected to the second transmission line.

15. The antenna substrate of claim 14, wherein D<L is satisfied, L is the size of the radiation electrode in a predetermined direction along a straight line connecting the feed point and the center of the radiation electrode, and D is the distance from the center of the through-hole wiring to the end of the first transmission line on the side of the second transmission line in the predetermined direction.

16. The antenna substrate according to claim 14 or 15, wherein the second transmission line and the radiation electrode have a mesh structure.

17. The antenna substrate according to claim 16, wherein the second transmission line and the radiation electrode have the same mesh structure.

18. The antenna substrate of claim 17, wherein the mesh structure comprises: a plurality of first linear conductors extending in a third direction and parallel to each other; and a plurality of second linear conductors extending in a fourth direction different from the third direction and intersecting with the plurality of first linear conductors, wherein the third direction corresponds to the length direction of the second transmission line; and the fourth direction does not correspond to the length direction of the second transmission line.

19. A display device comprising: the antenna substrate according to claim 14 or 15; and a display disposed on the second substrate opposite to the first substrate.

20. The display device of claim 19, wherein the second transmission line and the radiation electrode have the same mesh structure, the mesh structure comprising: a plurality of first linear conductors extending in a third direction and parallel to each other; and a plurality of second linear conductors extending in a fourth direction different from the third direction so as to intersect with the plurality of first linear conductors, the display having a plurality of pixels arranged in a fifth direction and a sixth direction intersecting the fifth direction, each of the third direction and the fourth direction being different from any of the longitudinal direction of the second transmission line, the fifth direction, and the sixth direction.

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