JP7360609B2 - Wiring board and wiring board manufacturing method - Google Patents

Description

Embodiments of the present disclosure relate to a wiring board and a method for manufacturing the wiring board.

Currently, mobile terminal devices such as smartphones and tablets are becoming more sophisticated, smaller, thinner, and lighter. Since these mobile terminal devices use multiple communication bands, multiple antennas are required depending on the communication bands. For example, mobile terminal devices include telephone antennas, WiFi (Wireless Fidelity) antennas, 3G (Generation) antennas, 4G (Generation) antennas, LTE (Long Term Evolution) antennas, and Bluetooth (registered trademark) antennas. , multiple antennas such as NFC (Near Field Communication) antennas are installed. However, as mobile terminal devices become smaller, the mounting space for antennas is limited, and the degree of freedom in antenna design is narrowed. Furthermore, since the antenna is built into a limited space, the radio wave sensitivity is not necessarily satisfactory.

JP2011-66610A Patent No. 5636735 specification Patent No. 5695947 specification

Furthermore, in recent years, development of mobile terminal devices for fifth generation communication, that is, 5G (Generation), has been progressing. This 5G antenna (particularly millimeter wave) has high directivity and requires a plurality of antennas to be built into the mobile terminal device.

This embodiment provides a wiring board and a method for manufacturing the wiring board, which can widen the bandwidth of radio waves transmitted and received by an antenna mesh wiring layer and expand the range of radio wave transmission and reception by disposing it in a display device. do.

The wiring board according to the present embodiment is a wiring board for a display device, and includes a transparent board, an antenna mesh wiring layer disposed on the board and functioning as an antenna, and an electrical connection layer to the antenna mesh wiring layer. and a parasitic array type mesh wiring layer disposed on the substrate and around the antenna mesh wiring layer.

In the wiring board according to the present embodiment, the antenna mesh wiring layer includes a plurality of first wirings arranged parallel to each other and a plurality of second wirings connecting the plurality of first wirings, and the antenna mesh wiring layer includes a plurality of second wirings connecting the plurality of first wirings, and The mesh wiring layer may include a plurality of third wirings arranged in parallel to each other and a plurality of fourth wirings connecting the plurality of third wirings.

In the wiring board according to the present embodiment, the length of the third wiring of the array type mesh wiring layer may be 80% or more and 120% or less of the length of the second wiring of the antenna mesh wiring layer. .

In the wiring board according to this embodiment, the antenna mesh wiring layer may have a square shape in plan view.

In the wiring board according to the present embodiment, the power feeding section may be located at an outer peripheral edge of the board.

In the wiring board according to this embodiment, the antenna mesh wiring layer may be provided at a position overlapping the display of the display device in plan view.

In the wiring board according to the present embodiment, a protective layer may be formed on the board so as to cover the antenna mesh wiring layer and the array type mesh wiring layer.

The method for manufacturing a wiring board according to the present embodiment is a method for manufacturing a wiring board, which includes a step of preparing a transparent board, an antenna mesh wiring layer functioning as an antenna, and an antenna mesh wiring layer on the board. forming a power feeding section electrically connected to the wiring layer; and a parasitic array mesh wiring layer disposed on the substrate and around the antenna mesh wiring layer. There is.

According to the embodiments of the present disclosure, by disposing it in a display device, it is possible to widen the bandwidth of radio waves transmitted and received by the antenna mesh wiring layer and expand the range of radio wave transmission and reception.

FIG. 1 is a plan view showing a wiring board according to one embodiment. FIG. 2 is an enlarged plan view showing an antenna mesh wiring layer of a wiring board according to an embodiment. FIG. 3 is a cross-sectional view (III-III line cross-sectional view in FIG. 2) showing a wiring board according to one embodiment. FIG. 4 is a cross-sectional view (cross-sectional view taken along the line IV--IV in FIG. 2) showing a wiring board according to one embodiment. FIG. 5 is an enlarged plan view showing an array-type mesh wiring layer of a wiring board according to an embodiment. FIG. 6 is an enlarged plan view showing the vicinity of the power feeding section of the wiring board according to one embodiment (an enlarged view of the VI section in FIG. 2). FIGS. 7(a)-(i) are cross-sectional views showing a method for manufacturing a wiring board according to an embodiment. FIG. 8 is a plan view showing an image display device according to an embodiment. FIG. 9 is a perspective view showing an image display device according to an embodiment. FIG. 10 is a cross-sectional view (cross-sectional view taken along line XX in FIG. 8) showing an image display device according to an embodiment. FIG. 11 is a plan view showing a wiring board according to a modified example.

First, one embodiment will be described with reference to FIGS. 1 to 10. 1 to 10 are diagrams showing this embodiment.

Each figure shown below is shown schematically. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. Further, it is possible to implement the invention with appropriate changes within the scope of the technical concept. In each figure shown below, the same parts are given the same reference numerals, and some detailed explanations may be omitted. In addition, the numerical values such as dimensions and material names of each member described in this specification are examples of embodiments, and are not limited to these, and can be appropriately selected and used. In this specification, terms specifying shapes and geometrical conditions, such as terms such as parallel, perpendicular, and perpendicular, are not only meant strictly, but also include substantially the same state.

Furthermore, in the following embodiments, the "X direction" is a direction parallel to one side of the substrate. The "Y direction" is a direction perpendicular to the X direction and parallel to the other side of the substrate. The "Z direction" is a direction perpendicular to both the X direction and the Y direction and parallel to the thickness direction of the wiring board. Further, the term "surface" refers to the surface on the positive side in the Z direction, on which the antenna mesh wiring layer and the array type mesh wiring layer are provided with respect to the substrate. The "back surface" refers to a surface on the negative side in the Z direction, which is opposite to the surface on which the antenna mesh wiring layer and the array type mesh wiring layer are provided with respect to the substrate.

[Wiring board configuration]
The configuration of the wiring board according to this embodiment will be described with reference to FIGS. 1 to 6. 1 to 6 are diagrams showing a wiring board according to this embodiment.

As shown in FIG. 1, a wiring board 10 according to this embodiment is used for a display device, and is placed, for example, on a display of an image display device. Such a wiring board 10 includes a transparent substrate 11, an antenna mesh wiring layer 20 disposed on the substrate 11, and a parasitic array type mesh wiring layer 30 disposed on the substrate 11. We are prepared. Further, a power feeding section 40 is electrically connected to the antenna mesh wiring layer 20.

Among them, the substrate 11 has a substantially rectangular shape in plan view, and its longitudinal direction is parallel to the Y direction, and its transversal direction is parallel to the X direction. The substrate 11 is transparent, has a substantially flat plate shape, and has a substantially uniform thickness as a whole. The length L ₁ of the substrate 11 in the longitudinal direction (Y direction) can be selected, for example, from 100 mm to 200 mm, and the length L ₂ of the substrate 11 in the lateral direction (X direction) is, for example, 50 mm or more. It can be selected within a range of 100 mm or less.

The material of the substrate 11 may be any material as long as it has transparency in the visible light region and electrical insulation properties. In this embodiment, the material of the substrate 11 is polyethylene terephthalate, but is not limited thereto. Examples of the material for the substrate 11 include polyester resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, polycarbonate resins, polyimide resins, polyolefin resins such as cycloolefin polymers, triacetyl cellulose, etc. It is preferable to use an organic insulating material such as a cellulose resin material. Further, as the material of the substrate 11, glass, ceramics, etc. can be selected as appropriate depending on the purpose. Although the substrate 11 is illustrated as being composed of a single layer, it is not limited thereto, and may have a structure in which a plurality of base materials or layers are laminated. Further, the substrate 11 may be in the form of a film or a plate. Therefore, the thickness of the substrate 11 is not particularly limited and can be selected as appropriate depending on the application, but as an example, the thickness (Z direction) T ₁ (see FIG. 3) of the substrate 11 is, for example, in the range of 10 μm or more and 200 μm or less. It can be done.

In this embodiment, the antenna mesh wiring layer 20 consists of an antenna pattern that functions as an antenna. In FIG. 1, a plurality (two) of antenna mesh wiring layers 20 are formed on a substrate 11, and each corresponds to the same or different frequency bands. The size of the antenna mesh wiring layer 20 corresponds to the frequency of radio waves transmitted and received by the antenna mesh wiring layer 20. That is, the antenna mesh wiring layer 20 has a substantially square shape when viewed from above, one side of which is parallel to the X direction, and the other side parallel to the Y direction. The length of one side of the antenna mesh wiring layer 20 (the length in the X direction and the Y direction) _La is the length corresponding to half the wavelength of the frequency of the radio waves transmitted and received by the antenna mesh wiring layer 20 ( _La = λ/ 2). Specifically, the length L _a of one side of the antenna mesh wiring layer 20 can be selected within a range of, for example, 4 mm or more and 50 mm or less. Note that only one antenna mesh wiring layer 20 may be arranged on the wiring board 10. Each antenna mesh wiring layer 20 corresponds to a telephone antenna, a WiFi antenna, a 3G antenna, a 4G antenna, a 5G antenna, an LTE antenna, a Bluetooth (registered trademark) antenna, an NFC antenna, etc. You can leave it there.

As shown in FIG. 2, the antenna mesh wiring layer 20 has metal wires each formed in a lattice shape or a mesh shape, and has a repeating pattern in the X direction and the Y direction. In other words, the antenna mesh wiring layer 20 has an L-shape that includes a portion extending in the X direction (a part of the second wiring 22 described later) and a portion extending in the Y direction (a part of the first wiring 21 described later). It is composed of repeating unit pattern shapes 20a.

As shown in FIG. 2, the antenna mesh wiring layer 20 includes a plurality of first wirings 21 arranged parallel to each other and a plurality of second wirings 22 connecting the plurality of first wirings 21. Specifically, the plurality of first wirings 21 and the plurality of second wirings 22 are integrated as a whole to form a lattice shape or a mesh shape. Each first wiring 21 extends in a direction parallel to one side of the antenna mesh wiring layer 20 (Y direction), and each second wiring 22 extends in a direction perpendicular to the first wiring 21 (X direction). . The first wiring 21 and the second wiring 22 each have a length L _a (the length of the side of the antenna mesh wiring layer 20 described above, see FIG. 1) corresponding to half the wavelength (λ/2) of a predetermined frequency. have

The plurality of first wirings 21 are arranged at equal intervals in the X direction. The pitch _P1 of the first wiring 21 can be, for example, in a range of 0.05 mm or more and 1 mm or less. Further, the plurality of second wirings 22 are arranged at equal intervals in the Y direction. The pitch _P2 of the plurality of second wirings 22 can be, for example, in a range of 0.01 mm or more and 1 mm or less.

Among the plurality of second wirings 22, the second wiring 22 that is farthest from the power feeding unit 40 (furthest on the positive side in the Y direction) mainly functions as an antenna. The second wiring 22 that functions as an antenna is shown in bold lines in FIG. The other second wiring 22 and the first wiring 21 serve to electrically connect the second wiring 22 functioning as an antenna and the power feeding section 40 . Moreover, the second wiring 22 and the first wiring 21 play a role of suppressing disconnection of the first wiring 21 and the second wiring 22 by being connected to each other.

As shown in FIG. 2, in the antenna mesh wiring layer 20, a plurality of openings 23 are formed by being surrounded by first wirings 21 adjacent to each other and second wirings 22 adjacent to each other. Each opening 23 has a substantially square shape in plan view. Furthermore, the transparent substrate 11 is exposed from each opening 23 . Therefore, by increasing the area of each opening 23, the transparency of the wiring board 10 as a whole can be improved. Note that, although each of the first wirings 21 and each of the second wirings 22 are orthogonal to each other, the present invention is not limited thereto, and they may intersect with each other at an acute angle or an obtuse angle. Furthermore, the pitch P ₁ of the first wiring 21 and the pitch P ₂ of the second wiring 22 are uniform within the antenna mesh wiring layer 20 , but are not limited thereto, and may be non-uniform within the antenna mesh wiring layer 20 .

As shown in FIG. 3, each first wiring 21 has a cross section perpendicular to its longitudinal direction (cross section in the X direction) having a substantially rectangular shape or a substantially square shape. In this case, the cross-sectional shape of the first wiring 21 is substantially uniform along the longitudinal direction (Y direction) of the first wiring 21. Further, as shown in FIG. 4, the shape of the cross section perpendicular to the longitudinal direction (Y direction cross section) of each second wiring 22 is approximately rectangular or approximately square, and the cross section (X The shape is almost the same as the direction cross section). In this case, the cross-sectional shape of the second wiring 22 is substantially uniform along the longitudinal direction (X direction) of the second wiring 22. The cross-sectional shapes of the first wiring 21 and the second wiring 22 do not necessarily have to be substantially rectangular or square. For example, the cross-sectional shape of the first wiring 21 and the second wiring 22 may be approximately narrower on the front side (positive side in the Z direction) than on the back side (minus side in the Z direction). It may have a trapezoidal shape or a shape with curved side surfaces located on both sides in the longitudinal direction.

In this embodiment, the line width W ₁ (length in the X direction, see FIG. 3) of the first wiring 21 and the line width W ₂ (length in the Y direction, see FIG. 4) of the second wiring 22 are particularly It is not limited and can be selected as appropriate depending on the purpose. For example, the line width W ₁ of the first wiring 21 can be selected in the range of 0.1 μm or more and 5.0 μm or less, and the line width W ₂ of the second wiring 22 can be selected in the range of 0.1 μm or more and 5.0 μm or less. can be selected. Further, the height H ₁ (length in the Z direction, see FIG. 3) of the first wiring 21 and the height H ₂ (length in the Z direction, see FIG. 4) of the second wiring 22 are not particularly limited. It can be selected as appropriate depending on, for example, in the range of 0.1 μm or more and 5.0 μm or less.

The first wiring 21 and the second wiring 22 may be made of any metal material as long as it has conductivity. In this embodiment, the material of the first wiring 21 and the second wiring 22 is copper, but the material is not limited thereto. As the material for the first wiring 21 and the second wiring 22, for example, metal materials (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used.

In the present embodiment, the aperture ratio At of the antenna mesh wiring layer 20 can be, for example, in a range of 87% or more and less than 100%. By setting the aperture ratio At of the antenna mesh wiring layer 20 within this range, the conductivity and transparency of the wiring board 10 can be ensured. Note that the aperture ratio refers to an open area (metal parts such as the first wiring 21 and second wiring 22 are not present and the substrate 11 is exposed) that occupies a unit area of a predetermined area (for example, the antenna mesh wiring layer 20). area).

As shown in FIG. 1, the array type mesh wiring layer 30 is arranged around each antenna mesh wiring layer 20. Specifically, the array type mesh wiring layer 30 is arranged on both sides of the antenna mesh wiring layer 20 in the X direction. These pair of array type mesh wiring layers 30 have the same shape and are spaced apart from the antenna mesh wiring layer 20, respectively.

The length L _b of the array type mesh wiring layer 30 in the longitudinal direction (Y direction) is the same as or slightly different from the side length L _a of the antenna mesh wiring layer 20, as described later. Further, the length L _c of the array type mesh wiring layer 30 in the width direction (X direction) can be selected within a range of, for example, 1 mm or more and 10 mm or less. The distance P _b between the array type mesh wiring layer 30 and the antenna mesh wiring layer 20 can be appropriately selected depending on the frequency band of radio waves transmitted and received by the antenna mesh wiring layer 20, and is, for example, 0.3 mm or more and 5 mm or less. can be in the range of In this case, the spacing between the array type mesh wiring layer 30 and the antenna mesh wiring layer 20 on one side and the spacing between the other array type mesh wiring layer 30 and the antenna mesh wiring layer 20 are the same, but they are different from each other. You can leave it there.

As shown in FIG. 5, the array type mesh wiring layer 30 has metal lines formed in a lattice shape or a mesh shape, and has a repeating pattern in the X direction and the Y direction. In other words, the array-type mesh wiring layer 30 has an L-shape that is composed of a portion extending in the X direction (a portion of the fourth wiring 32 described later) and a portion extending in the Y direction (a portion of the third wiring 31 described later). It is composed of repetitions of unit pattern shapes 30a.

The array type mesh wiring layer 30 includes a plurality of third wirings 31 arranged parallel to each other and a plurality of fourth wirings 32 connecting the plurality of third wirings 31. Specifically, the plurality of third wirings 31 and the plurality of fourth wirings 32 are integrated as a whole to form a lattice shape or a mesh shape. Each third wiring 31 extends in a direction (Y direction) parallel to the longitudinal direction of the array type mesh wiring layer 30, and each fourth wiring 32 extends in a direction parallel to the width direction (Y direction) of the array type mesh wiring layer 30. (X direction).

The length of the third wiring 31 (that is, the length L _b of the array type mesh wiring layer 30 ) is the length L _a of the second wiring 22 of the antenna mesh wiring layer 20 (the length of the radio waves transmitted and received by the antenna mesh wiring layer 20 ). It has a length that is the same as or slightly different from the length corresponding to half the wavelength of the frequency (λ/2, see FIG. 1). Specifically, the length L _b of the third wiring 31 has a length of 80% or more and 120% or less of the length L _a of the second wiring 22 of the antenna mesh wiring layer 20 (0.8L _a ≦L _b ≦1.2L _a ). By providing the array-type mesh wiring layer 30 in this way, it is possible to further widen the bandwidth of radio waves transmitted and received by the antenna mesh wiring layer 20 and to widen the radiation pattern of the antenna mesh wiring layer 20. In particular, by making the length L _b of the third wiring 31 slightly different from the length _{L a} of the second wiring 22 of the antenna mesh wiring layer 20, the peak of the resonant frequency of the antenna mesh wiring layer 20 can be adjusted. The bandwidth of radio waves transmitted and received by the antenna mesh wiring layer 20 can be expanded. On the other hand, the fourth wiring 32 plays a role of suppressing disconnection of the third wiring 31 by connecting the third wiring 31 to each other.

The plurality of third wirings 31 are arranged at equal intervals in the width direction (X direction) of the array type mesh wiring layer 30. The pitch P ₃ of the third wiring 31 can be the same as the pitch P ₁ of the first wiring 21 described above. The plurality of fourth wirings 32 are arranged at equal intervals in the longitudinal direction (Y direction) of the array type mesh wiring layer 30. The pitch P ₄ of the plurality of fourth wirings 32 can be the same as the pitch P ₂ of the second wirings 22 described above.

In the array type mesh wiring layer 30, a plurality of openings 33 are formed by being surrounded by third wirings 31 adjacent to each other and fourth wirings 32 adjacent to each other. Each opening 33 has a substantially square shape in plan view. Furthermore, the transparent substrate 11 is exposed from each opening 33 . Therefore, by increasing the area of each opening 33, the transparency of the wiring board 10 as a whole can be improved. Note that each of the third wirings 31 and each of the fourth wirings 32 are orthogonal to each other, but the present invention is not limited thereto, and they may intersect with each other at an acute angle or an obtuse angle. Further, the pitch P ₃ of the third wiring 31 and the pitch P ₄ of the fourth wiring 32 are uniform within the array type mesh wiring layer 30, but are not limited to this, and may be non-uniform within the array type mesh wiring layer 30. good.

The cross-sectional shape of each third wiring 31 perpendicular to the longitudinal direction (X-direction cross-section) can be the same as the cross-sectional shape of the first wiring 21 described above. Further, the cross-sectional shape of each fourth wiring 32 perpendicular to the longitudinal direction (Y-direction cross-section) can be the same as the cross-sectional shape of the second wiring 22 described above. Further, the line width (length in the X direction) of the third wiring 31 and the line width (length in the Y direction) of the fourth wiring 32 are the line width W ₁ of the first wiring 21 and the second wiring 22 described above, respectively. can be made the same as the line width _W2 . Furthermore, the height (length in the Z direction) of the third wiring 31 and the height (length in the Z direction) of the fourth wiring 32 are the height H ₁ of the first wiring 21 and the height H 1 of the second wiring 22 described above. It can be made equal to the height _H2 .

The material of the third wiring 31 and the fourth wiring 32 can also be the same as the material of the first wiring 21 and the second wiring 22 described above.

In the present embodiment, the aperture ratio As of the array-type mesh wiring layer 30 can be, for example, in a range of 87% or more and less than 100%. By setting the aperture ratio As of the array-type mesh wiring layer 30 within this range, the conductivity and transparency of the wiring board 10 can be ensured.

In this embodiment, the array type mesh wiring layer 30 is of a passive type and is not electrically connected to the power feeding section 40 or the antenna mesh wiring layer 20. That is, the outer periphery of the array-type mesh wiring layer 30 is not connected to any other metal part over the entire periphery, and is surrounded by the substrate 11 over the entire periphery in plan view.

On the other hand, the antenna mesh wiring layer 20 is of a power feeding type and is electrically connected to the power feeding section 40 . The outer periphery of the antenna mesh wiring layer 20 is surrounded by the substrate 11 over the entire circumference in plan view, except for the power feeding section 40. Note that the present invention is not limited to this, and the outer periphery of the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 (the outer periphery on the negative side in the Y direction) is the outer periphery of the substrate 11 (the outer periphery on the negative side in the Y direction) in plan view. It may be the same as

As shown in FIG. 6, the power supply section 40 has a substantially rectangular shape in plan view and is made of a conductive thin plate member. In this case, the longitudinal direction of the power feeding section 40 is parallel to the X direction, and the lateral direction of the power feeding section 40 is parallel to the Y direction. Further, the power feeding unit 40 is arranged at the outer peripheral edge (the end on the negative side in the Y direction) of the substrate 11. The power feeding unit 40 is connected to the second wiring 22 located furthest on the negative side in the Y direction. In this case, the power feeding section 40 may be formed integrally with the second wiring 22 located furthest on the negative side in the Y direction. As the material of the power supply unit 40, for example, metal materials (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used. This power supply unit 40 is electrically connected to the wireless communication circuit 94 of the image display device 90 via the power supply line 95 when the wiring board 10 is incorporated into the image display device 90 (see FIGS. 8 to 10). Ru. Note that although the power feeding section 40 is provided on the surface of the substrate 11, the present invention is not limited thereto, and part or all of the power feeding section 40 may be located outside the outer peripheral edge of the substrate 11. Further, by forming the power supply section 40 flexibly, the power supply section 40 may wrap around the side surface or the back surface of the image display device 90 and be electrically connected to the side surface or the back surface of the substrate 11.

Furthermore, as shown in FIGS. 3 and 4, a protective layer 17 is formed on the surface of the substrate 11 so as to cover the antenna mesh wiring layer 20 and the array type mesh wiring layer 30. The protective layer 17 protects the antenna mesh wiring layer 20 and the array type mesh wiring layer 30, and is formed over substantially the entire surface of the substrate 11. Materials for the protective layer 17 include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate, modified resins and copolymers thereof, polyvinyl such as polyester, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, and polyvinyl butyral. Colorless and transparent insulating resins such as resins and their copolymers, polyurethane, epoxy resins, polyamides, and chlorinated polyolefins can be used. Further, the thickness T ₂ of the protective layer 17 can be selected within the range of 0.3 μm or more and 100 μm or less. Note that the protective layer 17 may be formed so as to cover at least the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 of the substrate 11 .

[Method for manufacturing wiring board]
Next, a method for manufacturing a wiring board according to this embodiment will be described with reference to FIGS. 7(a) to 7(i). 7(a)-(i) are cross-sectional views showing a method for manufacturing a wiring board according to this embodiment.

First, as shown in FIG. 7A, a substrate 11 is prepared, and a conductive layer 51 is formed on substantially the entire surface of the substrate 11. In this embodiment, the thickness of conductive layer 51 is 200 nm. However, the thickness of the conductive layer 51 is not limited thereto, and can be appropriately selected within the range of 10 nm or more and 1000 nm or less. In this embodiment, the conductive layer 51 is formed using copper by a sputtering method. As a method for forming the conductive layer 51, a plasma CVD method may be used.

Next, as shown in FIG. 7(b), a photocurable insulating resist 52 is applied to substantially the entire surface of the substrate 11. As this photocurable insulating resist 52, for example, organic resin such as epoxy resin can be used.

Next, a transparent mold 53 for imprinting having a convex portion 53a is prepared (FIG. 7(c)), the mold 53 and the substrate 11 are brought close to each other, and photocuring is performed between the mold 53 and the substrate 11. Then, the insulating resist 52 is developed. Next, the insulating layer 54 is formed by irradiating light from the mold 53 side to harden the photocurable insulating resist 52. As a result, a trench 54a having a shape in which the convex portion 53a is transferred is formed on the surface of the insulating layer 54. The trench 54a has a planar pattern corresponding to the first wiring 21, the second wiring 22, the third wiring 31, and the fourth wiring 32.

Thereafter, the mold 53 is peeled off from the insulating layer 54 to obtain the insulating layer 54 having the cross-sectional structure shown in FIG. 7(d).

In this way, by forming the trenches 54a on the surface of the insulating layer 54 by the imprint method, the shape of the trenches 54a can be made fine. Note that the present invention is not limited to this, and the insulating layer 54 may be formed by a photolithography method. In this case, a resist pattern is formed by photolithography to expose the conductive layer 51 corresponding to the first wiring 21, second wiring 22, third wiring 31, and fourth wiring 32.

As shown in FIG. 7D, residues of the insulating material may remain at the bottom of the trench 54a of the insulating layer 54. Therefore, the residue of the insulating material is removed by performing a wet treatment using a permanganate solution or N-methyl-2-pyrrolidone, or a dry treatment using oxygen plasma. By removing the residue of the insulating material in this manner, a trench 54a in which the conductive layer 51 is exposed can be formed as shown in FIG. 7(e).

Next, as shown in FIG. 7(f), the trench 54a of the insulating layer 54 is filled with a conductor 55. In this embodiment, trenches 54a of insulating layer 54 are filled with copper using electrolytic plating using conductive layer 51 as a seed layer.

Subsequently, as shown in FIG. 7(g), the insulating layer 54 is removed. In this case, the insulating layer 54 on the substrate 11 is removed by wet processing using a permanganate solution or N-methyl-2-pyrrolidone or dry processing using oxygen plasma.

Next, as shown in FIG. 7(h), the conductive layer 51 on the surface of the substrate 11 is removed. At this time, the conductive layer 51 is etched by performing a wet process using hydrogen peroxide solution so that the surface of the substrate 11 is exposed. In this way, a wiring board 10 is obtained that includes the substrate 11, the antenna mesh wiring layer 20 disposed on the substrate 11, and the array-type mesh wiring layer 30 disposed around the antenna mesh wiring layer 20. . In this case, the antenna mesh wiring layer 20 includes a first wiring 21 and a second wiring 22. Further, the array type mesh wiring layer 30 includes a third wiring 31 and a fourth wiring 32. At this time, a portion of the conductor 55 forms the power feeding section 40 . Alternatively, a flat power supply section 40 may be prepared separately and this power supply section 40 may be electrically connected to the antenna mesh wiring layer 20.

Thereafter, as shown in FIG. 7(i), a protective layer 17 is formed to cover the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 on the substrate 11. Methods for forming the protective layer 17 include roll coating, gravure coating, gravure reverse coating, microgravure coating, slot die coating, die coating, knife coating, inkjet coating, dispenser coating, kiss coating, spray coating, screen printing, offset printing, and flexography. Printing may also be used.

[Operation of this embodiment]
Next, the operation of the wiring board having such a configuration will be described.

As shown in FIGS. 8 to 10, the wiring board 10 is incorporated into an image display device (display device) 90 having a display 91. As shown in FIGS. Examples of such an image display device 90 include mobile terminal devices such as a smartphone and a tablet.

The image display device 90 includes a housing 92 , a display 91 housed in the housing 92 , and a wireless communication circuit 94 housed in the housing 92 . A power supply line 95 is connected to the wireless communication circuit 94 . The power supply line 95 extends in the thickness direction (Z direction) on the side surface of the image display device 90 (see FIG. 9). Wiring board 10 is placed on display 91 . Further, the antenna mesh wiring layer 20 of the wiring board 10 is provided at a position where at least a portion thereof overlaps the display 91 in plan view. The antenna mesh wiring layer 20 is electrically connected to the wireless communication circuit 94 of the image display device 90 via the power feeding section 40 and the power feeding line 95. In this way, radio waves of a predetermined frequency can be transmitted and received via the antenna mesh wiring layer 20, and communication can be performed using the image display device 90.

By the way, in general, when the antenna mesh wiring layer 20 is, for example, a 5G antenna (particularly a millimeter wave antenna), the bandwidth of radio waves transmitted and received by the antenna mesh wiring layer 20 tends to be narrow and the directivity tends to be strong. In contrast, in this embodiment, a parasitic array type mesh wiring layer 30 is provided on the substrate 11 and around the antenna mesh wiring layer 20. Thereby, the bandwidth of radio waves transmitted and received by the antenna mesh wiring layer 20 can be further expanded, and the directivity of the antenna of the antenna mesh wiring layer 20 can be expanded. In this case, by adjusting the length (Y direction distance) of the array type mesh wiring layer 30, the bandwidth of the radio waves transmitted and received by the antenna mesh wiring layer 20 can be further widened.

Further, according to the present embodiment, the wiring board 10 includes a transparent substrate 11, an antenna mesh wiring layer 20, and an array-type mesh wiring layer 30 arranged on the substrate 11. The antenna mesh wiring layer 20 and the array-type mesh wiring layer 30 have a mesh-like pattern consisting of a conductor portion as a forming portion of an opaque conductor layer and a large number of openings, so that the wiring board 10 is transparent. gender is ensured. As a result, when the wiring board 10 is placed on the display 91, the display 91 can be visually recognized through the opening 23 of the antenna mesh wiring layer 20 and the opening 33 of the array type mesh wiring layer 30, and the display 91 can be visually recognized. Sexuality is not hindered.

Further, according to the present embodiment, the antenna mesh wiring layer 20 includes a plurality of second wirings 22 that connect a plurality of first wirings 21, and the array type mesh wiring layer 30 includes a plurality of third wirings 31. It includes a plurality of fourth wirings 32 that are connected. Thereby, the first wiring 21, the second wiring 22, the third wiring 31, and the fourth wiring 32 can be made difficult to disconnect, and the functions of the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 can be prevented from deteriorating. Can be suppressed.

Further, according to the present embodiment, the length L _b of the third wiring 31 of the array type mesh wiring layer 30 is greater than or equal to 80% and less than or equal to 120% of the length L _a of the second wiring 22 of the antenna mesh wiring layer 20 . It is. As a result, by appropriately adjusting the length L _b of the third wiring 31, the peak of the resonant frequency of the antenna mesh wiring layer 20 can be adjusted, and the bandwidth of radio waves transmitted and received by the antenna mesh wiring layer 20 can be expanded. be able to.

(Modified example)
Next, a modification of the wiring board will be described.

FIG. 11 shows a modified example of the wiring board. The modification shown in FIG. 11 differs in the arrangement of the antenna mesh wiring layer 20 and the array type mesh wiring layer 30, and the other configurations are substantially the same as the embodiment shown in FIGS. 1 to 10 described above. In FIG. 11, the same parts as those in the form shown in FIGS. 1 to 10 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the wiring board 10A shown in FIG. 11, eight (plural) antenna mesh wiring layers 20 are arranged on the board 11. Two (plural) antenna mesh wiring layers 20 are arranged on each of the longitudinal direction (Y direction) side and the transverse direction (X direction) side of the substrate 11 . A pair of parasitic array-type mesh wiring layers 30 is arranged around each antenna mesh wiring layer 20, respectively.

In this way, by arranging the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 along all sides of the substrate 11, the bandwidth and directivity of radio waves transmitted and received by the antenna mesh wiring layer 20 can be further expanded. I can do it. Note that the antenna mesh wiring layer 20 and the array type mesh wiring layer 30 may be arranged along two or three sides of the substrate 11.

It is also possible to appropriately combine the plurality of components disclosed in the above embodiments and modifications as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiments and modifications.

10 Wiring board 11 Substrate 17 Protective layer 20 Antenna mesh wiring layer 21 First wiring 22 Second wiring 23 Opening 30 Array type mesh wiring layer 31 Third wiring 32 Fourth wiring 33 Opening 40 Power feeding part

Claims (8)

A wiring board for a display device,
a transparent substrate;
an antenna mesh wiring layer disposed on the substrate and functioning as an antenna;
a power feeding section electrically connected to the antenna mesh wiring layer;
a parasitic array type mesh wiring layer disposed on the substrate and around the antenna mesh wiring layer,
The power feeding unit is provided at a position where the entirety thereof does not overlap the display of the display device in plan view ,
The antenna mesh wiring layer has an aperture ratio of 87% or more and less than 100%,
The antenna mesh wiring layer includes a plurality of first wirings arranged parallel to each other and a plurality of second wirings connecting the plurality of first wirings, and the line width of the first wiring is 0.1 μm or more. 5.0 μm or less, and the line width of the second wiring is 0.1 μm or more and 5.0 μm or less,
The wiring board , wherein the array type mesh wiring layer has an aperture ratio of 87% or more and less than 100% . 2. The wiring board according to claim 1, wherein the array type mesh wiring layer includes a plurality of third wirings arranged in parallel to each other and a plurality of fourth wirings connecting the plurality of third wirings. 3. The wiring board according to claim 2, wherein the length of the third wiring of the array type mesh wiring layer is 80% or more and 120% or less of the length of the second wiring of the antenna mesh wiring layer. The wiring board according to any one of claims 1 to 3, wherein the antenna mesh wiring layer has a square shape in plan view. The wiring board according to any one of claims 1 to 4, wherein the power feeding section is located at an outer peripheral edge of the board. The wiring board according to any one of claims 1 to 5, wherein the antenna mesh wiring layer is provided at a position overlapping a display of the display device in plan view. 7. The wiring board according to claim 1, wherein a protective layer is formed on the substrate so as to cover the antenna mesh wiring layer and the array type mesh wiring layer. A method for manufacturing a wiring board, the method comprising:
a step of preparing a transparent substrate;
On the substrate, an antenna mesh wiring layer functioning as an antenna, a power feeding part electrically connected to the antenna mesh wiring layer, and a parasitic array type mesh wiring arranged around the antenna mesh wiring layer. a step of forming a layer;
The power feeding unit is provided at a position where the entirety thereof does not overlap the display of the display device in plan view ,
The antenna mesh wiring layer has an aperture ratio of 87% or more and less than 100%,
The antenna mesh wiring layer includes a plurality of first wirings arranged parallel to each other and a plurality of second wirings connecting the plurality of first wirings, and the line width of the first wiring is 0.1 μm or more. 5.0 μm or less, and the line width of the second wiring is 0.1 μm or more and 5.0 μm or less,
The method for manufacturing a wiring board , wherein the array type mesh wiring layer has an aperture ratio of 87% or more and less than 100% .

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