阅读说明：本技术 配线基板和配线基板的制造方法 (Wiring board and method for manufacturing wiring board ) 是由 铃木纲一 武诚司 松浦大辅 于 2019-09-19 设计创作，主要内容包括：配线基板(10)具有：具有透明性的基板(11)；以及配线图案区域(20),其配置于基板(11)上,包含有多个配线(21、22)。配线图案区域(20)的方块电阻值为5Ω/□以下,以120°的视角观察各配线(21、22)时的最大宽度为3μm以下。(A wiring board (10) is provided with: a substrate (11) having transparency; and a wiring pattern region (20) which is disposed on the substrate (11) and includes a plurality of wirings (21, 22). The wiring pattern region (20) has a square resistance value of 5 omega/□ or less, and a maximum width of 3 [ mu ] m or less when the wirings (21, 22) are viewed from a 120 DEG viewing angle.)

1. A wiring board, wherein,

the wiring board includes:

a substrate having transparency; and

a wiring pattern region disposed on the substrate and including a plurality of wirings,

the wiring pattern region has a sheet resistance value of 5 omega/□ or less,

the maximum width of each wiring when viewed from a 120 DEG viewing angle is 3 [ mu ] m or less.

2. The wiring substrate according to claim 1,

in a cross section of each wiring, the shorter one of the height and the line width is 2 times or less the skin depth of each wiring.

3. The wiring substrate according to claim 1,

the aspect ratio of at least one wiring is 0.5 or more.

4. The wiring substrate according to claim 1,

the plurality of wires each have: a top surface; a bottom surface; and a pair of side surfaces between the top surface and the bottom surface,

a region of the pair of side surfaces of at least one of the wirings on the bottom surface side has a curved shape such that a width thereof becomes narrower toward the bottom surface.

5. The wiring substrate according to claim 1,

the plurality of wires each have: a top surface; a bottom surface; and a pair of side surfaces between the top surface and the bottom surface,

a region of the pair of side surfaces of at least one of the wirings on the bottom surface side has a shape curved so that a width thereof becomes narrower toward the bottom surface,

a tapered surface is formed in a region of at least one of the pair of side surfaces of the other at least one wire closer to the bottom surface.

6. The wiring substrate according to claim 1,

the plurality of wires each have: a top surface; a bottom surface; and a pair of side surfaces between the top surface and the bottom surface,

the top surface of at least one wiring protrudes toward the opposite side of the substrate.

7. The wiring substrate according to claim 1,

an easy adhesion layer is formed on the substrate.

8. The wiring substrate according to claim 7,

and a sealing layer is formed on the easy-bonding layer.

9. The wiring substrate according to claim 1,

a protective layer is formed on the substrate so as to cover the plurality of wires.

10. The wiring substrate according to claim 1,

the wiring pattern region has a function as an antenna.

11. The wiring substrate according to claim 1,

the wiring board is provided with a plurality of wiring pattern regions, and the longitudinal direction of a part of the wiring pattern regions and the longitudinal direction of another part of the wiring pattern regions are oriented in different directions.

12. A method for manufacturing a wiring board, wherein,

the method for manufacturing the wiring substrate comprises the following steps:

preparing a substrate having transparency; and

a step of forming a wiring pattern region on the substrate, the wiring pattern region including a plurality of wirings,

the wiring pattern region has a sheet resistance value of 5 omega/□ or less,

the maximum width of each wiring when viewed from a 120 DEG viewing angle is 3 [ mu ] m or less.

Technical Field

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

Background

At present, portable terminal devices such as smartphones and tablet computers are increasingly being developed to have high functionality, small size, thin profile, and light weight. These mobile terminal devices require a plurality of antennas corresponding to a plurality of communication bands in order to use the communication bands. For example, a portable terminal device is mounted with a plurality of antennas such as a telephone antenna, a WiFi (Wireless Fidelity) antenna, a 3G (Generation: third Generation digital Communication) antenna, a 4G (Generation: fourth Generation digital Communication) antenna, an LTE (Long Term Evolution) antenna, a Bluetooth (registered trademark) antenna, and an NFC (Near Field Communication) antenna. However, with the miniaturization of portable terminal devices, the mounting space of antennas is limited, and the degree of freedom in antenna design is limited. Further, since the antenna is built in a limited space, the radio wave sensitivity is not necessarily satisfied.

Therefore, a film antenna which can be mounted in a display region of a mobile terminal device has been developed. The film antenna is a transparent antenna in which an antenna pattern is formed on a transparent base material, wherein the antenna pattern is formed of a mesh-like conductive mesh layer including a conductive portion as a formation portion of an opaque conductive layer and a plurality of openings as non-formation portions.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-66610

Patent document 2: japanese patent No. 5636735

Patent document 3: japanese patent No. 5695947

In the conventional film antenna, a wiring pattern region (a conductive mesh layer) is mounted on a transparent base material, but the wiring pattern region is easily observed by the naked eye due to the mesh shape of the wiring pattern region.

The present embodiment provides a wiring board and a method for manufacturing the wiring board, which can make a wiring pattern area difficult to be seen by naked eyes.

Disclosure of Invention

The wiring board of the present embodiment includes: a substrate having transparency; and a wiring pattern region disposed on the substrate and including a plurality of wirings, wherein the wiring pattern region has a block resistance value of 5 Ω/□ or less and a maximum width of 3 μm or less when each wiring is viewed from a 120 ° viewing angle.

In the wiring board of the present embodiment, in the cross section of each wiring, the shorter one of the height and the line width may be 2 times or less the skin depth of each wiring.

In the wiring board of the present embodiment, the aspect ratio of at least one wiring may be 0.5 or more.

In the wiring board of the present embodiment, each of the plurality of wires may include: a top surface; a bottom surface; and a pair of side surfaces located between the top surface and the bottom surface, wherein a region of the pair of side surfaces of at least one of the wirings on the bottom surface side has a shape curved so that a width thereof becomes narrower toward the bottom surface.

In the wiring board of the present embodiment, each of the plurality of wires may include: a top surface; a bottom surface; and a pair of side surfaces located between the top surface and the bottom surface, wherein a region of at least one of the pair of side surfaces of the at least one wiring on the bottom surface side has a shape curved so as to narrow in width toward the bottom surface, and a tapered surface is formed in a region of at least one of the pair of side surfaces of the other at least one wiring on the bottom surface side.

In the wiring board of the present embodiment, each of the plurality of wires may include: a top surface; a bottom surface; and a pair of side surfaces between the top surface and the bottom surface, the top surface of at least one wiring protruding toward an opposite side of the substrate.

In the wiring board of the present embodiment, an easy adhesion layer may be formed on the board.

In the wiring board of the present embodiment, an adhesion layer may be formed on the easy adhesion layer.

In the wiring board of the present embodiment, a protective layer may be formed on the substrate so as to cover the plurality of wirings.

In the wiring board of the present embodiment, the wiring pattern region may function as an antenna.

In the wiring board of the present embodiment, the wiring board may be provided with a plurality of the wiring pattern regions, and a longitudinal direction of a part of the wiring pattern regions and a longitudinal direction of another part of the wiring pattern regions may be oriented in different directions from each other.

The method for manufacturing a wiring board of the present embodiment includes: preparing a substrate having transparency; and forming a wiring pattern region on the substrate, the wiring pattern region including a plurality of wirings, the wiring pattern region having a sheet resistance value of 5 Ω/□ or less and a maximum width of 3 μm or less when each wiring is viewed from a 120 ° viewing angle.

According to the embodiment of the present disclosure, it is possible to make it difficult to see the wiring pattern area by the naked eye.

Drawings

Fig. 1 is a plan view showing a wiring board according to an embodiment.

Fig. 2 is an enlarged plan view showing a wiring board according to an embodiment (an enlarged view of a portion II in fig. 1).

Fig. 3 is an enlarged plan view showing a wiring board according to an embodiment (an enlarged view of a portion III in fig. 2).

Fig. 4 is a cross-sectional view (cross-sectional view taken along line VI-VI in fig. 3) showing a wiring board according to an embodiment.

Fig. 5 is a cross-sectional view (cross-sectional view along line V-V of fig. 3) showing a wiring board according to an embodiment.

Fig. 6 is a sectional view showing the wiring.

Fig. 7 is a graph showing the results obtained by simulating the relationship between the block resistance value and the radiation efficiency.

Fig. 8 is a perspective view showing a wiring pattern region.

Fig. 9 is a sectional view showing the wiring.

Fig. 10 (a) to (e) are cross-sectional views showing a method of manufacturing a wiring board according to an embodiment.

Fig. 11 (a) to (e) are cross-sectional views showing a method of manufacturing a wiring board according to an embodiment.

Fig. 12 is a plan view showing an image display device according to an embodiment.

Fig. 13 is a plan view showing a wiring board according to modification 1.

Fig. 14 (a) and (b) are cross-sectional views showing the wiring of the wiring board according to modification 2.

Fig. 15 (a) and (b) are cross-sectional views showing the wiring of the wiring board according to modification 3.

Detailed Description

First, an embodiment will be described with reference to fig. 1 to 12. Fig. 1 to 12 are diagrams illustrating the present embodiment.

The drawings shown below are schematically illustrated. Therefore, the size and shape of each part are exaggerated as appropriate for easy understanding. The present invention can be modified and implemented as appropriate without departing from the scope of the technical idea. In the drawings described below, the same components are denoted by the same reference numerals, and detailed description of the components may be omitted. The numerical values and material names of the components described in the present specification, such as dimensions, are examples of embodiments, and are not limited to these values, and can be selected and used as appropriate. In the present specification, terms for specifying the shape and the geometric condition, for example, terms such as parallel, orthogonal, and perpendicular, include substantially the same state except for strict meanings.

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 substrate. The "front surface" refers to a surface on the Z-direction positive side, and refers to a surface on which wiring is provided on the substrate. The "back surface" refers to a surface on the negative side in the Z direction and is a surface opposite to the surface on which the wiring is provided on the substrate.

[ Structure of Wiring Board ]

The structure of the wiring board of the present embodiment will be described with reference to fig. 1 to 5. Fig. 1 to 5 are diagrams illustrating a wiring board according to the present embodiment.

As shown in fig. 1, the wiring board 10 of the present embodiment is disposed on, for example, a display of an image display device. Such a wiring board 10 includes: a substrate 11 having transparency; and a wiring pattern area 20 disposed on the substrate 11. The power feeding portion 40 is electrically connected to the wiring pattern region 20.

The substrate 11 has a substantially rectangular shape in plan view, and the longitudinal direction thereof is parallel to the Y direction and the short direction thereof is parallel to the X direction. The substrate 11 is transparent and has a substantially flat plate shape, and the thickness thereof is substantially uniform as a whole. Length L of substrate 11 in the longitudinal direction (Y direction)₁For example, the length L in the short side direction (X direction) of the substrate 11 can be selected within the range of 100mm to 200mm₂For example, the thickness can be selected from the range of 50mm to 100 mm. In addition, the corners of the substrate 11 are rounded.

The material of the substrate 11 may be any material having transparency in the visible light region and electrical insulation. In the present embodiment, the material of the substrate 11 is polyethylene terephthalate, but is not limited thereto. As the material of the substrate 11, for example, 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 are preferably used. As the material of the substrate 11, glass, ceramic, or the like can be appropriately selected according to the application. In addition, although the substrate 11 is illustrated as being formed of one layer, the present invention is not limited thereto, and a structure in which a plurality of substrates or layers are laminated may be employed. 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 appropriately selected according to the application, but the thickness of the substrate 11 is, for example(Z direction) T₁The thickness (see fig. 4 and 5) can be set to a range of 10 μm to 200 μm, for example.

In the present embodiment, the wiring pattern region 20 is constituted by an antenna pattern region having a function as an antenna. In fig. 1, a plurality of (3) wiring pattern regions 20 are formed on the substrate 11, and correspond to different frequency bands. That is, the length (length in the Y direction) L of the plurality of wiring pattern areas 20_aDifferent from each other, and each has a length corresponding to a specific frequency band. The length L of the wiring pattern region 20 increases as the frequency band of the corresponding band becomes lower_aThe longer. When the wiring board 10 is disposed on, for example, the display 91 (see fig. 12 described later) of the image display device 90, each wiring pattern region 20 may correspond to any antenna among a telephone antenna, a WiFi antenna, a 3G antenna, a 4G antenna, an LTE antenna, a Bluetooth (registered trademark) antenna, an NFC antenna, and the like.

Each of the wiring pattern regions 20 has a substantially rectangular shape in plan view. The long side direction of each wiring pattern region 20 is parallel to the Y direction, and the short side direction (width direction) thereof is parallel to the X direction. The length L in the longitudinal direction (Y direction) of each wiring pattern region 20_aFor example, the thickness can be selected from the range of 3mm to 100 mm. As described later, the width W in the short side direction (width direction) of each wiring pattern region 20_aIs determined by considering the following factors: (i) the skin depth of the 1 st direction wiring 21 and the 2 nd direction wiring 22; (ii) the block resistance value of the wiring pattern area 20; and (iii) the 1 st direction wiring 21 and the 2 nd direction wiring 22. Specifically, the width W of each wiring pattern region 20_aFor example, the thickness can be selected from the range of 1mm to 25 mm.

In the wiring pattern region 20, the metal lines are formed in a lattice shape or a mesh shape, respectively, and have a repetitive pattern in the X direction and the Y direction. That is, the wiring pattern region 20 has a pattern shape including a portion extending in the X direction (the 2 nd direction wiring 22) and a portion extending in the Y direction (the 1 st direction wiring 21).

As shown in fig. 2, each of the wiring pattern areas 20 includes: having multiple functions as antennas1 st direction wiring (antenna wiring) 21; and a plurality of 2 nd direction wires (antenna connection wires) 22 connecting the plurality of 1 st direction wires 21. Specifically, the plurality of 1 st-direction wires 21 and the plurality of 2 nd-direction wires 22 are integrated into a lattice shape or a mesh shape. Each 1 st-direction wiring 21 extends in a direction (longitudinal direction, Y direction) corresponding to the frequency band of the antenna, and each 2 nd-direction wiring 22 extends in a direction (width direction, X direction) perpendicular to the 1 st-direction wiring 21. The 1 st direction wiring 21 has a length L corresponding to a predetermined frequency band_a(the length of the wiring pattern region 20 described above, see fig. 1), and thereby functions mainly as an antenna. On the other hand, the 2 nd direction wire 22 connects the 1 st direction wires 21 to each other, thereby suppressing the following disadvantages: the 1 st direction wiring 21 is disconnected or the 1 st direction wiring 21 and the power feeding portion 40 are not electrically connected.

In each wiring pattern region 20, a plurality of openings 23 are formed by being surrounded by the 1 st-direction wirings 21 adjacent to each other and the 2 nd-direction wirings 22 adjacent to each other. Each of the openings 23 has a substantially rectangular shape or a substantially square shape in plan view, and the areas thereof are uniform. The transparent substrate 11 is exposed from each opening 23. Therefore, by increasing the total area of the openings 23 per unit area of the wiring pattern region 20, the transparency of the wiring board 10 as a whole can be improved.

As shown in fig. 3, the 1 st-direction wirings 21 are spaced apart from each other in the width direction (X direction) of the wiring pattern region 20 (pitch P)₁) And is configured. In this case, the 1 st-direction wirings 21 are arranged at uniform intervals along the width direction (X direction) of the wiring pattern region 20. The pitch P of the 1 st-direction wiring 21 is as described later₁Is determined in consideration of (i) the skin depth of the 1 st-direction wiring 21, (ii) the sheet resistance value of the wiring pattern region 20, and (iii) the viewing angle of the 1 st-direction wiring 21. Specifically, the pitch P of the 1 st-direction wiring 21₁For example, the thickness can be set to a range of 0.01mm to 1 mm. In addition, the pitch P of the 1 st direction wiring 21₁The wiring pattern area 20 is uniform along the width direction (X direction), but is not limited thereto, andmay be non-uniform along the width direction (X direction).

The plurality of 2 nd-direction wires 22 are arranged at equal intervals in the longitudinal direction (Y direction) of the wiring pattern region 20. The pitch P of the 2 nd direction wiring 22 will be described later₂Is determined in consideration of (i) the skin depth of the 2 nd-direction wiring 22, (ii) the sheet resistance value of the wiring pattern region 20, and (iii) the viewing angle of the 2 nd-direction wiring 22. Specifically, the pitch P of the 2 nd-direction wiring 22₂For example, the thickness can be set to a range of 0.01mm to 1 mm. The 1 st-direction wires 21 and the 2 nd-direction wires 22 are perpendicular to each other, but the present invention is not limited thereto, and may intersect each other at an acute angle or an obtuse angle. Further, the pitch P of the 2 nd direction wiring 22₂The wiring pattern region 20 is uniform along the longitudinal direction (Y direction), but is not limited thereto, and may not be uniform along the longitudinal direction (Y direction). In the present embodiment, the pitch P of the 1 st-direction wiring 21₁Pitch P from 2 nd direction wiring 22₂Same, but not limited thereto, pitch P₁And a pitch P₂Or may be different from each other.

As shown in fig. 4, each 1 st-direction wiring 21 has a substantially rectangular shape or a substantially square shape in cross section (cross section in the X direction) perpendicular to the longitudinal direction thereof. In this case, the 1 st-direction wiring 21 has a substantially uniform cross-sectional shape along the longitudinal direction (Y direction) of the 1 st-direction wiring 21. As shown in fig. 5, each of the 2 nd-direction wirings 22 has a substantially rectangular shape or a substantially square shape in a cross section (Y-direction cross section) perpendicular to the longitudinal direction, and is substantially the same as the cross section (X-direction cross section) of the 1 st-direction wiring 21 described above. In this case, the cross-sectional shape of the 2 nd-direction wiring 22 is substantially uniform along the longitudinal direction (X direction) of the 2 nd-direction wiring 22. The cross-sectional shapes of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 are not necessarily substantially rectangular or substantially square, and may be, for example, substantially trapezoidal shapes having a front surface side (Z-direction positive side) narrower than a back surface side (Z-direction negative side), or shapes having side surfaces on both sides in the longitudinal direction curved.

In the present embodiment, as described later, the 1 st directional wiring 21 has a line width W₁(length in X-direction, seeFIG. 4) and height H₁The length in the Z direction (see fig. 4) is determined in consideration of (i) the skin depth of the 1 st-direction wiring 21, (ii) the sheet resistance value of the wiring pattern region 20, and (iii) the viewing angle of the 1 st-direction wiring 21. For example, the line width W of the 1 st direction wiring 21₁Can be selected from the range of 0.1 μm to 3.0 μm, and the height H of the 1 st direction wiring 21₁For example, it can be selected from the range of 0.1 μm to 3.0 μm.

Similarly, as described later, the 2 nd direction wiring 22 has a line width W₂(length in Y-direction, see FIG. 5) and height H₂The length in the Z direction (see fig. 5) is determined in consideration of (i) the skin depth of the 2 nd direction wiring 22, (ii) the sheet resistance value of the wiring pattern region 20, and (iii) the viewing angle of the 2 nd direction wiring 22. For example, the line width W of the 2 nd direction wiring 22₂Can be selected from the range of 0.1 μm to 3.0 μm, and the height H of the 2 nd direction wiring 22₂For example, it can be selected from the range of 0.1 μm to 3.0 μm.

As shown in fig. 4 and 5, an easy adhesion layer 15 is formed on the substrate 11. The easy adhesion layer 15 is formed on substantially the entire front surface of the substrate 11 to improve adhesion between the substrate 11 and the 1 st-direction wiring 21 and the 2 nd-direction wiring 22. The easy adhesion layer 15 is made of an insulating coating film. As a material of the easy adhesion layer 15, for example, acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate, modified resins and copolymers thereof, polyethylene resins such as polyester, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, and polyvinyl butyral, and copolymers thereof, and colorless and transparent resins such as polyurethane, epoxy resin, polyamide, and chlorinated polyolefin can be used. The thickness of the easy adhesion layer 15 can be set as appropriate within a range of 10nm to 800 nm. The easy adhesion layer 15 may be formed on at least the wiring pattern region 20 on the front surface of the substrate 11.

An adhesion layer 16 is formed on the easy adhesion layer 15. The adhesion layer 16 is located between the easy adhesion layer 15 and the 1 st-direction wiring 21 and the 2 nd-direction wiring 22. The adhesion layer 16 is for improving adhesion between the substrate 11 and the 1 st-direction wiring 21 and the 2 nd-direction wiring 22, and the adhesion layer 16 is formed in the same planar shape as the 1 st-direction wiring 21 and the 2 nd-direction wiring 22. That is, the adhesion layer 16 has a lattice shape or a mesh shape in a plan view. As a material of the adhesion layer 16, for example, a metal Oxide such as titanium, titanium Oxide, nickel Oxide, Indium-Zinc-Oxide (IZO) or the like can be used. The thickness of the adhesion layer 16 can be selected from the range of 10nm to 100 nm. Further, the adhesive layer 16 may not be necessarily provided.

A protective layer 17 is formed on the front surface of the substrate 11 so as to cover the 1 st-direction wiring 21, the 2 nd-direction wiring 22, and the easy-adhesion layer 15. The protective layer 17 protects the 1 st-direction wiring 21 and the 2 nd-direction wiring 22, and is formed on substantially the entire front surface of the substrate 11. As a material of the protective layer 17, acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate, modified resins and copolymers thereof, polyethylene resins such as polyester, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, and polyvinyl butyral, copolymers thereof, and colorless and transparent insulating resins such as polyurethane, epoxy resin, polyamide, and chlorinated polyolefin can be used. The thickness of the protective layer 17 can be selected from the range of 0.3 μm to 10 μm. The protective layer 17 may be formed to cover at least the wiring pattern region 20 of the substrate 11.

The aperture ratio At of the wiring pattern region 20 as a whole can be set to a range of 87% or more and less than 100%, for example. By setting the aperture ratio At of the entire wiring board 10 to this range, the conductivity and transparency of the wiring board 10 can be ensured. The aperture ratio is a ratio (%) of the area of the opening region (the region where the substrate 11 is exposed without the metal portion such as the 1 st direction wiring 21 and the 2 nd direction wiring 22) to the unit area of a predetermined region (for example, the entire region of the wiring pattern region 20).

The material of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 may be any metal material having conductivity. In the present embodiment, the material of the 1 st direction wiring 21 and the 2 nd direction wiring 22 is copper, but is not limited thereto. As the material of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22, for example, a metal material (including an alloy of these materials) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used.

In the present embodiment, the mesh shapes (sizes) of the 1 st direction wires 21 and the 2 nd direction wires 22 of the wiring pattern region 20 are determined in consideration of (i) the skin depths of the 1 st direction wires 21 and the 2 nd direction wires 22, (ii) the block resistance values of the wiring pattern region 20, and (iii) the viewing angles of the 1 st direction wires 21 and the 2 nd direction wires 22. A method of determining the mesh shape (size) of the wiring pattern area 20 will be described below.

(i) Skin depth

As described above, the length (length in the Y direction) L of the wiring pattern area 20_aHas a length corresponding to a specific frequency band, the lower the frequency band, the length L_aThe longer. The length L of the wiring pattern area 20 is determined_aThen, the line widths W of the 1 st direction wiring 21 and the 2 nd direction wiring 22 are determined₁、W₂And height H₁、H₂。

That is, the line width W of the 1 st direction wiring 21 and the 2 nd direction wiring 22₁、W₂And height H₁、H₂The size of the band is determined according to the frequency band so as not to affect the skin effect. Specifically, in the cross section of the 1 st direction wiring 21 and the 2 nd direction wiring 22, the height H is set₁、H₂Sum line width W₁、W₂The shorter one of the first to third direction wirings 21 and 2 is 2 times or less the skin depth of each of the 1 st direction wirings 21 and 2 nd direction wirings 22.

In general, when an alternating current flows through a wire, the higher the frequency, the more difficult it is for the current to flow in the center portion of the wire, and thus, the current flows on the surface of the wire. In this way, a phenomenon in which a current flows only on the surface when an alternating current flows through the wiring is referred to as a skin effect. Further, the skin depth means: decays to a depth from the surface of the wiring of 1/e (about 0.37) times the current of the surface of the wiring where the current is most likely to flow. The skin depth δ can be generally obtained by the following equation.

[ equation 1]

In the above formula, ω is an angular frequency (═ 2 π f), and μ is a magnetic permeability (4 π × 10 in vacuum)^-7[H/m]) σ denotes the conductivity of a conductor constituting the wiring (5.8 × 10 in the case of copper)⁷[S/m]). As for the skin depth δ of the copper wiring, δ is about 2.3 μm in the case of a frequency of 0.8GHz, δ is about 1.3 μm in the case of a frequency of 2.4GHz, δ is about 1.0 μm in the case of a frequency of 4.4GHz, and δ is about 0.85 μm in the case of a frequency of 6 GHz.

In the present embodiment, the height H of the 1 st-direction wiring 21 (2 nd-direction wiring 22)₁(H₂) Sum line width W₁(W₂) The shorter one of the two is 2 times (2 δ) or less the skin depth δ of the corresponding frequency. For example, as shown in FIG. 6, the line width W₁(W₂) Is higher than the height H of the 1 st direction wiring 21 (2 nd direction wiring 22)₁(H₂) Short case (W)₁＜H₁(W₂＜H₂) Next, the line width W of the 1 st direction wiring 21 (2 nd direction wiring 22) is set₁(W₂) The skin depth delta is set to be less than 2 times (W) of the corresponding frequency₁≤2δ(W₂2 delta or less). For example, W is W when the frequency of the wiring pattern region 20 is 2.4GHz₁(W₂) Is 2.6 μm or less, and W is W when the frequency of the wiring pattern region 20 is 6GHz₁(W₂) Is 1.7 μm or less.

This allows a current to flow substantially over the entire cross section of the 1 st-direction wiring 21 (2 nd-direction wiring 22). Therefore, the 1 st-direction wiring 21 (2 nd-direction wiring 22) can be efficiently used, and the cross-sectional area of the 1 st-direction wiring 21 (2 nd-direction wiring 22) can be minimized. As a result, the aperture ratio At of the wiring pattern region 20 can be increased, and the wiring pattern region 20 can be made difficult to see with the naked eye.

(ii) Square resistance value

The wiring pattern region 20 has a square resistance value of 5 Ω/□ or less. By setting the block resistance value to 5 Ω/□ or less, the performance of the wiring pattern region 20 can be maintained. Specifically, the radiation efficiency of the wiring pattern region 20 as an antenna (a ratio indicating how much power input to the wiring pattern region 20 alone is radiated) can be improved.

Fig. 7 shows a result of simulation of a relationship between a square resistance value and a radiation efficiency in the case where the frequency corresponding to the wiring pattern area 20 as an antenna is 2.4 GHz. As is clear from fig. 7, by setting the square resistance value of the wiring pattern region 20 to 5 Ω/□ or less, the radiation efficiency of the wiring pattern region 20 alone is 75% or more, and the antenna characteristics can be maintained. On the other hand, when the sheet resistance value of the wiring pattern region 20 exceeds 5 Ω/□, the radiation efficiency of the wiring pattern region 20 may be less than 75%. In addition, when the frequency corresponding to the wiring pattern region 20 is a frequency other than 2.4 GHz: by setting the square resistance value to 5 Ω/□ or less, the radiation efficiency can be maintained well.

Here, the square resistance value (Ω/□) of the wiring pattern region 20 can be obtained as follows. That is, both ends 20 in the longitudinal direction (Y direction) of the measured wiring pattern area 20_e1、20_e2(see fig. 8) resistance values R between. Then, the resistance value R is divided by the length L of the wiring pattern region 20_aAnd width W_aRatio of (L)_a/W_a) Thus, the block resistance R of the wiring pattern area 20 can be obtained_s(omega/□). I.e. the square resistance R_s＝R×W_a/L_a。

By setting the square resistance value of the wiring pattern region 20 to 5 Ω/□ or less in this way, the radiation efficiency of the wiring pattern region 20 alone can be set to 75% or more, and the performance of the wiring pattern region 20 as an antenna can be improved. Further, the width W of the wiring pattern region 20 can be set within the range satisfying the square resistance value_aAnd height H₁、H₂As much as possible to a minimum. Therefore, the aperture ratio At of the wiring pattern region 20 can be increased, making it difficult to see the wiring pattern region 20.

(iii) Angle of view

In the present embodiment, the maximum width of each of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 when viewed from a 120 ° viewing angle is 3 μm or less.

That is, as shown in fig. 9, in a cross section perpendicular to the longitudinal direction of the 1 st-direction wiring 21 (2 nd-direction wiring 22), a predetermined line of sight L is defined_DIn the direction of the first direction wiring 21 (the second direction wiring 22)_D. Furthermore, the line of sight L_DThe width of the 1 st direction wiring 21 (2 nd direction wiring 22) which becomes the longest when moving within the range of the viewing angle of 120 ° is 3 μm or less.

Here, the viewing angle means a normal N to be perpendicular to the front surface of the substrate 11_LAnd towards the normal N_LIntersection O with the front surface of the substrate 11_ZLine of sight L_DThe angle between the two is 2 × θ. Furthermore, from the line of sight L_DWidth W when viewed in the direction of (1)_DThe method comprises the following steps: in a cross-sectional view with the line of sight L_DA pair of parallel straight lines L_m、L_nA pair of straight lines L when contacting the 1 st direction wiring 21 (2 nd direction wiring 22)_m、L_nThe distance between them.

For example, the height H of the 1 st direction wiring 21 (2 nd direction wiring 22)₁(H₂) The line width W of the 1 st direction wiring 21 (2 nd direction wiring 22)₁(W₂) Same condition (H)₁＝W₁(H₂＝W₂) Width W when observed at a 120 DEG angle of view_DThe longest value at θ of 45 ° is 1.41 × W₁. Further, the height H of the 1 st direction wiring 21 (2 nd direction wiring 22)₁(H₂) Is the line width W of the 1 st direction wiring 21 (2 nd direction wiring 22)₁(W₂)2 times of (H)₁＝2×W₁(H₂＝2×W₂) Width W when observed at a 120 DEG angle of view_DThe longest value at 60 ° is 2.23 × W₁。

In general, when a user views the wiring board 10, the viewing angle is considered to be at most about 120 °. The width of the 1 st direction wiring 21 (2 nd direction wiring 22) that can be seen by a human being is about 3 μm at most. Therefore, by setting the maximum width of the 1 st direction wiring 21 (2 nd direction wiring 22) to 3 μm or less when viewed from a 120 ° viewing angle, it is possible to make it difficult for a user to visually recognize the 1 st direction wiring 21 (2 nd direction wiring 22).

Referring again to fig. 1, the power feeding portion 40 is electrically connected to the wiring pattern region 20. The power supply portion 40 is formed of a conductive thin plate-like member having a substantially rectangular shape. The longitudinal direction of the power supply unit 40 is parallel to the X direction, and the lateral direction of the power supply unit 40 is parallel to the Y direction. The power supply unit 40 is disposed at an end in the longitudinal direction of the substrate 11 (a negative end in the Y direction). As a material of the power supply portion 40, for example, a metal material (including an alloy of these materials) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used. When the wiring board 10 is incorporated into the image display device 90 (see fig. 12), the power supply unit 40 is electrically connected to the wireless communication circuit 92 of the image display device 90. The power supply portion 40 is provided on the front surface of the substrate 11, but the present invention is not limited thereto, and a part or the whole of the power supply portion 40 may be located outside the peripheral edge of the substrate 11. Further, by making the power supply portion 40 flexible, the power supply portion 40 may be wound around the side surface or the rear surface of the image display device 90 and may be electrically connected to the side surface or the rear surface.

[ method for manufacturing Wiring Board ]

Next, a method for manufacturing a wiring board according to the present embodiment will be described with reference to fig. 10 (a) to (e) and fig. 11 (a) to (e). Fig. 10 (a) - (e) and fig. 11 (a) - (e) are cross-sectional views showing the method of manufacturing the wiring board of the present embodiment.

First, as shown in fig. 10 (a), a substrate 11 is prepared, and the easy adhesion layer 15 and the adhesive layer 16 are sequentially formed on substantially the entire front surface of the substrate 11. As a method for forming the easy-adhesion layer 15, roll coating, gravure coating, reverse gravure coating, micro gravure coating, slot die coating, knife coating, inkjet coating, dispensing coating (ディスペンサーコート), kiss coating (キスコート), and spray coating can be used. As a method for forming the adhesive layer 16, an evaporation method, a sputtering method, or a plasma CVD method can be used.

Next, as shown in fig. 10 (b), a conductive layer 51 is formed on the adhesive layer 16 over substantially the entire front surface of the substrate 11. In this embodiment, the thickness of the conductive layer 51 is 200 nm. However, without being limited thereto, the thickness of the conductive layer 51 can be appropriately selected within a range of 10nm or more and 1000nm or less. In this embodiment, the conductive layer 51 is formed by a sputtering method using copper. As a method for forming the conductive layer 51, a plasma CVD method can be used.

Next, as shown in fig. 10(c), a photocurable insulating resist 52 is provided on the adhesion layer 16 over substantially the entire front surface of the substrate 11. Examples of the photocurable insulating resist 52 include organic resins such as epoxy resins.

Next, a transparent imprint mold 53 having a convex portion 53a is prepared (fig. 10 d), the mold 53 and the substrate 11 are brought close to each other, and the photocurable insulating resist 52 is developed between the mold 53 and the substrate 11. Next, the insulating layer 54 is formed by irradiating light from the mold 53 side and curing the photocurable insulating resist 52. Thus, a groove 54a is formed on the front surface of the insulating layer 54, and the groove 54a has a shape to which the projection 53a is transferred. The groove 54a has a planar shape pattern corresponding to the 1 st direction wiring 21 and the 2 nd direction wiring 22.

After that, the mold 53 is peeled off from the insulating layer 54, thereby obtaining the insulating layer 54 having a cross-sectional structure shown in fig. 10 (e). The direction in which the mold 53 is peeled off from the insulating layer 54 is preferably the Y direction in which the longer 1 st-direction wiring 21 extends.

In this way, by forming the trench 54a on the front surface of the insulating layer 54 by the imprint method, the shape of the trench 54a can be made fine. In addition, without limitation, the insulating layer 54 may be formed by photolithography. In this case, a resist pattern is formed by photolithography so that the conductive layer 51 corresponding to the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 is exposed.

Next, as shown in fig. 11 (a), a residue of the insulating material may remain at the bottom of the trench 54a in the insulating layer 54. Therefore, the residue of the insulating material is removed by wet treatment using an organic solvent such as a permanganate solution or N-methyl-2-pyrrolidone, or dry treatment using oxygen plasma. By removing the residue of the insulating material in this way, as shown in fig. 11 (a), a trench 54a exposing the conductive layer 51 can be formed.

Next, as shown in fig. 11 (b), the trench 54a of the insulating layer 54 is filled with a conductor 55. In this embodiment, the trenches 54a of the insulating layer 54 are filled with copper by an electroplating method using the conductive layer 51 as a seed layer.

Next, as shown in fig. 11 (c), the insulating layer 54 is removed. In this case, the insulating layer 54 on the substrate 11 is removed by wet treatment using an organic solvent such as a permanganate solution or N-methyl-2-pyrrolidone, or dry treatment using oxygen plasma.

Next, as shown in fig. 11 (d), the conductive layer 51 and the adhesive layer 16 on the front surface of the substrate 11 are removed. At this time, the conductive layer 51 and the adhesive layer 16 are etched by wet treatment using a copper etching solution such as an aqueous solution of ferric chloride, an aqueous solution of cupric chloride, an aqueous solution of ammonium peroxodisulfate, an aqueous solution of sodium peroxodisulfate, sulfuric acid, or hydrogen peroxide so that the front surface of the substrate 11 is exposed.

Thereafter, as shown in fig. 11 (e), the protective layer 17 is formed so as to cover the easy adhesion layer 15, the conductor 55, and the adhesion layer 16 on the substrate 11. As a method for forming the protective layer 17, roll coating, gravure coating, reverse gravure coating, micro gravure coating, slot die coating, knife coating, inkjet coating, dispensing coating (ディスペンサーコート), kiss coating (キスコート), spray coating, screen printing, offset printing, and flexographic printing can be used.

Thus, the wiring board 10 having the substrate 11 and the wiring pattern region 20 disposed on the substrate 11 was obtained (fig. 11 (e)). In this case, the wiring pattern region 20 includes the 1 st direction wiring 21 and the 2 nd direction wiring 22. The conductor 55 includes a 1 st direction wiring 21 and a 2 nd direction wiring 22. At this time, the power feeding portion 40 may be formed by a part of the conductor 55. Alternatively, a plate-shaped power supply portion 40 may be separately prepared, and the power supply portion 40 may be electrically connected to the wiring pattern region 20.

[ Effect of the present embodiment ]

Next, the operation of the wiring board configured by such a structure will be described.

As shown in fig. 12, the wiring board 10 is incorporated in an image display device 90 having a display 91. The wiring board 10 is disposed on the display 91. Examples of such an image display device 90 include portable terminal devices such as smartphones and tablet computers. The wiring pattern area 20 of the wiring substrate 10 is electrically connected to the wireless communication circuit 92 of the image display device 90 via the power feeding unit 40. In this way, radio waves of a predetermined frequency can be transmitted and received via the wiring pattern area 20, and communication can be performed using the image display device 90.

As described above, according to the present embodiment, the wiring pattern region 20 of the wiring board 10 has a sheet resistance of 5 Ω/□ or less, and the maximum widths of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 when viewed from a 120 ° viewing angle are 3 μm or less, respectively. This makes it difficult to observe the wiring pattern region 20 on the front surface of the display 91, and makes it difficult for the user of the image display device 90 to visually recognize the wiring pattern region 20. That is, the width W of the wiring pattern area 20 can be set to be within the range of the square resistance of 5 Ω/□ or less_aAnd height H₁、H₂As much as possible, it is possible to increase the aperture ratio At of the wiring pattern region 20, making it difficult to see the wiring pattern region 20. Further, since the maximum widths when the 1 st direction wiring 21 and the 2 nd direction wiring 22 are viewed from the 120 ° viewing angle are respectively 3 μm or less, it is possible to make it difficult for the user to recognize the 1 st direction wiring 21 and the 2 nd direction wiring 22 with the naked eye.

Further, according to the present embodiment, by setting the sheet resistance value of the wiring pattern region 20 to 5 Ω/□ or less, the radiation efficiency of the wiring pattern region 20 alone can be set to 75% or more. This can improve the performance of the wiring pattern region 20 as an antenna.

Further, in accordance with the present implementationIn the cross section of the 1 st direction wiring 21 and the 2 nd direction wiring 22, the height H₁、H₂Sum line width W₁、W₂The shorter one of the lines is 2 times or less the skin depth of the 1 st-direction line 21 and the 2 nd-direction line 22. This enables the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 to be efficiently used in the cross section, and the cross-sectional area can be minimized. As a result, the aperture ratio At of the wiring pattern region 20 can be increased, and the wiring pattern region 20 can be made less visible.

Further, according to the present embodiment, since the easy adhesion layer 15 is formed on the substrate 11, the adhesion between the substrate 11 and the 1 st direction wiring 21 and the 2 nd direction wiring 22 can be improved. Furthermore, since the adhesion layer 16 is formed on the easy adhesion layer 15, the adhesion between the substrate 11 and the 1 st direction wiring 21 and the 2 nd direction wiring 22 can be further improved.

Further, according to the present embodiment, since the protective layer 17 is formed on the substrate 11 so as to cover the 1 st direction wiring 21 and the 2 nd direction wiring 22, the 1 st direction wiring 21 and the 2 nd direction wiring 22 can be protected from external impact or the like.

Further, according to the present embodiment, the wiring pattern region 20 has a function as an antenna. The wiring pattern region 20 as an antenna can be disposed on the outermost surface side of the image display device 90. Therefore, the communication performance can be improved as compared with a case where the antenna is incorporated in the image display device 90. Further, since a plurality of wiring pattern regions 20 as antennas can be arranged in the plane of the image display device 90, the communication performance can be further improved.

(modification example)

Next, various modifications of the wiring board will be described.

(modification 1)

Fig. 13 shows a 1 st modification of the wiring board. In the modification shown in fig. 13, the configuration of the wiring pattern region 20 is different, and the other configurations are substantially the same as those of the above-described embodiment shown in fig. 1 to 12. In fig. 13, the same components as those shown in fig. 1 to 12 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the wiring board 10A shown in fig. 13, a plurality of wiring pattern regions 20(20A to 20d) are arranged on the substrate 11. In this case, the longitudinal direction of one part of the wiring trace region 20 and the longitudinal direction of the other part of the wiring trace region 20 are directed in different directions from each other. Specifically, the longitudinal direction of some of the wiring pattern regions 20(20a to 20b) among the plurality of wiring pattern regions 20 is parallel to each side (X direction or Y direction) of the substrate 11. The longitudinal direction of the other part of the wiring pattern region 20(20c) is not parallel to (inclined with respect to) each side (X direction and Y direction) of the substrate 11. A pair of the partial wiring pattern regions 20(20d) is arranged line-symmetrically, and constitutes a dipole antenna.

Generally, the higher the frequency band of the radio wave received by the wiring pattern region 20, the shorter the length of the wiring pattern region 20. Therefore, the number of the wiring pattern regions 20 arranged on the substrate 11 can be increased. However, there is a tendency that: the higher the frequency band of the received radio wave, the lower the directivity of the wiring pattern area 20 as an antenna. Therefore, by disposing the wiring pattern regions 20 facing in the respective directions on the substrate 11, such a decrease in directivity can be suppressed.

(modification 2)

Fig. 14 (a) and (b) show a 2 nd modification of the present disclosure. Fig. 14 (a) is a cross-sectional view perpendicular to the longitudinal direction of the 1 st-direction wiring 21, and fig. 14 (b) is a cross-sectional view perpendicular to the longitudinal direction of the 2 nd-direction wiring 22. In the modification shown in fig. 14 (a) and (b), the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 are different in shape, and the other configuration is substantially the same as that of the embodiment shown in fig. 1 to 12. In fig. 14 (a) and (b), the same components as those shown in fig. 1 to 12 are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in fig. 14 (a), the 1 st-direction wiring 21 has a top surface 21a, a bottom surface 21b, and a pair of side surfaces 21c between the top surface 21a and the bottom surface 21 b. The top surface 21a is a surface located on the opposite side of the substrate 11, and the bottom surface 21b is a surface located on the substrate 11 side. The top surface 21a and the bottom surface 21b are respectively located on planes substantially parallel to the principal surface of the substrate 11. The pair of side surfaces 21c are surfaces located on both sides (the X-direction positive side and the X-direction negative side) of the 1 st-direction wiring 21.

Each side surface 21c has a top surface side protruding portion 21d, an intermediate recessed portion 21e, an intermediate protruding portion 21f, and a bottom surface side bent portion 21g from the top surface 21a side toward the bottom surface 21b side. The top-surface side protrusion 21d is a region located on the top surface 21a side, and protrudes outward in the width direction (X direction) of the 1 st-direction wiring 21. The intermediate recessed portion 21e is bent inward in the width direction of the 1 st-direction wiring 21 than the top-surface-side protruding portion 21 d. The intermediate protruding portion 21f protrudes outward in the width direction of the 1 st-direction wiring 21 from the intermediate recessed portion 21 e. The bottom surface-side bent portion 21g is a region of the 1 st-direction wiring 21 on the bottom surface 21b side, and has a shape that is bent inward in the width direction so that the width thereof becomes narrower from the intermediate protruding portion 21f toward the bottom surface 21 b.

As described above, by recessing the intermediate concave portion 21e inward in the width direction of the 1 st-direction wiring 21, the adhesion between the 1 st-direction wiring 21 and the protective layer 17 can be improved, and the protective layer 17 can be prevented from peeling off from the 1 st-direction wiring 21. Further, since the region (bottom surface side bent portion 21g) on the bottom surface 21b side of the 1 st direction wiring 21 is bent so that the width becomes narrower toward the bottom surface 21b, it is possible to make it difficult for the user to visually recognize the 1 st direction wiring 21. The intermediate recessed portion 21e and the bottom surface side bent portion 21g may be provided only on one side surface 21c of the pair of side surfaces 21 c.

In this case, the 1 st direction wiring 21 has a line width W₁Defined by the portion of the 1 st direction wiring 21 having the largest width. Specifically, the 1 st direction wiring 21 has a line width W₁Refers to the width of the 1 st direction wiring 21 at the top surface side protrusion 21 d. The 1 st direction wiring 21 has a line width W₁Can be selected from the range of 0.1 μm to 3.0 μm. Further, the portion of the 1 st-direction wiring 21 having the narrowest width may be an intermediate recessed portion 21e, and the 1 st-direction wiring 21 may have a line width W in the intermediate recessed portion 21e₃Is 0.08 to 2.6 μm inclusive. Height H of 1 st direction wiring 21₁For example, it can be selected from the range of 0.1 μm to 3.0 μm.

Aspect ratio of 1 st direction wiring 21(W₁/H₁) Preferably 0.5 or more, more preferably 1.0 or more. By increasing the aspect ratio of the 1 st-direction wiring 21 in this way, the 1 st-direction wiring 21 is made difficult to visually recognize when viewed from the front side (Z-direction front side), and the cross-sectional area of the 1 st-direction wiring 21 can be increased to reduce the resistance value of the 1 st-direction wiring 21. As a result, both the invisibility and the performance (low resistance) of the 1 st direction wiring 21 can be improved.

As shown in fig. 14 (b), the 2 nd-direction wiring 22 has a top surface 22a, a bottom surface 22b, and a pair of side surfaces 22c between the top surface 22a and the bottom surface 22 b. The top surface 22a is a surface located on the opposite side of the substrate 11, and the bottom surface 22b is a surface located on the substrate 11 side. The top surface 22a and the bottom surface 22b are each located on a plane substantially parallel to the main surface of the substrate 11. The pair of side surfaces 22c are surfaces located on both sides (Y-direction positive side and Y-direction negative side) of the 2 nd-direction wiring 22.

Each side surface 22c has a top surface side protrusion 22d, an intermediate recess 22e, and a bottom surface side tapered portion 22f from the top surface 22a side toward the bottom surface 22b side. The top-surface side protrusion 22d is a region located on the top surface 22a side, and protrudes outward in the width direction (Y direction) of the 2 nd-direction wiring 22. The intermediate recessed portion 22e is bent inward in the width direction of the 2 nd-direction wiring 22 with respect to the top-surface-side protruding portion 22 d. The bottom surface-side tapered portion 22f is a region of the 2 nd direction wiring 22 on the bottom surface 22b side, and is a tapered surface having a tip expanding in width from the intermediate recessed portion 22e toward the bottom surface 22 b.

Since the intermediate recessed portion 22e is recessed inward in the width direction of the 2 nd-direction wiring 22, the adhesion between the 2 nd-direction wiring 22 and the protective layer 17 can be improved, and the protective layer 17 can be prevented from peeling off from the 2 nd-direction wiring 22. Further, since the tapered surface (bottom surface side tapered portion 22f) is formed in the region of the side surface 22c on the bottom surface 22b side, the adhesion between the 2 nd direction wiring 22 and the substrate 11 can be improved. The intermediate recessed portion 22e and the tapered surface (bottom surface side tapered portion 22f) may be provided only on one of the pair of side surfaces 22 c.

In this case, the 2 nd direction wiring 22 has a line width W₂Defined by the portion of the 2 nd direction wiring 22 having the largest width. Specifically, the 2 nd directionLine width W of wiring 22₂The width of the 2 nd direction wiring 22 at the bottom surface side tapered portion 22 f. The 2 nd direction wiring 22 has a line width W₂Can be selected from the range of 0.1 μm to 3.0 μm. Further, the portion of the 2 nd-direction wiring 22 having the narrowest width may be the intermediate concave portion 22e, and the width W of the 2 nd-direction wiring 22 in the intermediate concave portion 22e may be₄Is in the range of 0.08 to 2.6 μm. Height H of 2 nd direction wiring 22₂For example, it can be selected from the range of 0.1 μm to 3.0 μm.

Aspect ratio (W) of the 2 nd direction wiring 22₂/H₂) Preferably 0.5 or more, more preferably 1.0 or more. In this way, by increasing the aspect ratio of the 2 nd direction wire 22, the 2 nd direction wire 22 can be made difficult to be visually recognized when viewed from the front side (Z direction positive side), and the cross-sectional area of the 2 nd direction wire 22 can be increased to reduce the resistance value of the 2 nd direction wire 22. As a result, both the invisibility and the performance (low resistance) of the 2 nd direction wiring 22 can be improved.

The sectional shapes of the 1 st direction wiring 21 and the 2 nd direction wiring 22 shown in fig. 14 (a) and (b) are formed by etching. Specifically, the shapes (such as the shape of the side surface and the shape of the curved surface) of the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 can be adjusted by appropriately setting the etching conditions (such as the type and concentration of the etching solution and the etching time) when the conductive layer 51 and the adhesive layer 16 (see fig. 11 d) are etched.

As described above, in the present modification, the sectional shape of the 1 st-direction wiring 21 and the sectional shape of the 2 nd-direction wiring 22 are different from each other. Specifically, the region on the bottom surface 21b side of the pair of side surfaces 21c of the 1 st-direction wiring 21 is bent so that the width thereof becomes narrower toward the bottom surface 21b, and the region on the bottom surface 22b side of the pair of side surfaces 22c of the 2 nd-direction wiring 22 is formed with a tapered surface. This makes it difficult to visually recognize the 1 st-direction wiring 21 when viewed from the front side (Z-direction front side), and improves the adhesion between the 2 nd-direction wiring 22 and the substrate 11.

When the wiring board 10 is disposed on the display 91 (see fig. 12) of the image display device 90, there is a standard direction of use, and when used in this direction, it is desirable that the wiring pattern region 20 is difficult to see. The sectional shape of the 1 st-direction wiring 21 and the sectional shape of the 2 nd-direction wiring 22 are preferably set to: the wiring pattern region 20 is difficult to be observed in a normal use direction and the adhesion between the wiring pattern region 20 and the substrate 11 can be improved. Therefore, the sectional shape of the 1 st direction wiring 21 and the sectional shape of the 2 nd direction wiring 22 may be reversed depending on the standard use direction. For example, the 1 st-direction wiring 21 may have a cross-sectional shape shown in fig. 14 (b), and the 2 nd-direction wiring 22 may have a cross-sectional shape shown in fig. 14 (a).

In addition, when the plurality of 1 st direction wires 21 have a function as an antenna, the pitch between the 1 st direction wires 21 is narrower than the pitch between the 2 nd direction wires 22, so that the function of the entire wiring pattern region 20 can be improved. In this case, by designing the sectional shape of the 1 st-direction wiring 21 and the sectional shape of the 2 nd-direction wiring 22 as shown in fig. 14 (a) and (b), visibility of the 1 st-direction wiring 21 can be suppressed, and adhesion between the 2 nd-direction wiring 22 and the substrate 11 can be improved.

The sectional shape of the 1 st-direction wiring 21 and the sectional shape of the 2 nd-direction wiring 22 may not be different from each other. For example, the 2 nd direction wiring 22 may have the same cross-sectional shape as the 1 st direction wiring 21. The aspect ratio of each of the 1 st direction wiring 21 and the 2 nd direction wiring 22 may not be 0.5 or more. For example, the aspect ratio of the 1 st direction wiring 21 or the 2 nd direction wiring 22 may be less than 0.5.

In fig. 14 (a) and (b), the easy adhesion layer 15 and the adhesive layer 16 are not shown (the same applies to fig. 15 (a) and (b) described later).

(modification 3)

Fig. 15 (a) and (b) show a 3 rd modification of the present disclosure. Fig. 15 (a) is a cross-sectional view perpendicular to the longitudinal direction of the 1 st-direction wiring 21, and fig. 15 (b) is a cross-sectional view perpendicular to the longitudinal direction of the 2 nd-direction wiring 22. In the modification shown in fig. 15 (a) and (b), the 1 st-direction wiring 21 and the 2 nd-direction wiring 22 have different cross-sectional shapes, and the other configurations are substantially the same as those of the modification 2 shown in fig. 14 (a) and (b). In fig. 15 (a) and (b), the same components as those shown in fig. 1 to 14 are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in fig. 15 (a), a convex portion 21h is formed on the top surface 21a of the 1 st-direction wiring 21. The convex portion 21h is formed in a mountain shape and protrudes toward the front surface side (the opposite side to the substrate 11). The convex portion 21h is located substantially at the center in the width direction of the 1 st-direction wiring 21.

As shown in fig. 15 (b), a convex portion 22h is formed on the top surface 22a of the 2 nd direction wiring 22. The convex portion 22h is formed in a mountain shape and protrudes toward the front surface side (the opposite side to the substrate 11). The convex portion 22h is located at the approximate center in the width direction of the 2 nd-direction wiring 22.

By providing the convex portions 21h and 22h on the top surface 21a of the 1 st direction wiring 21 and the top surface 22a of the 2 nd direction wiring 22, respectively, the adhesion between the 1 st direction wiring 21 and the 2 nd direction wiring 22 and the protective layer 17 can be improved, and the protective layer 17 can be prevented from being peeled off from the 1 st direction wiring 21 and the 2 nd direction wiring 22. Further, the sectional area of the 1 st direction wiring 21 and the 2 nd direction wiring 22 can be increased, and the resistance values of the 1 st direction wiring 21 and the 2 nd direction wiring 22 can be decreased.

The projections 21h and 22h may be provided only on one of the 1 st direction wiring 21 and the 2 nd direction wiring 22.

In fig. 1 to 15, the case where the wiring pattern region 20 functions as an antenna is described as an example, but the present invention is not limited thereto. The wiring pattern area 20 can also realize functions such as hovering (a function that can operate even if a user does not directly touch the display), fingerprint authentication, a heater, noise reduction (noise shielding), and the like. In such a case, the sheet resistance of the wiring pattern region 20 is set to 5 Ω/□ or less, and the maximum width when the 1 st direction wiring 21 and the 2 nd direction wiring 22 are viewed at a 120 ° viewing angle is set to 3 μm or less, whereby the wiring pattern region 20 can be made difficult to be viewed, and the wiring pattern region 20 can be made difficult to be recognized by a user with the naked eye.

A plurality of constituent elements disclosed in the above-described embodiment and modification can be appropriately combined as necessary. Alternatively, some of the components may be deleted from all the components shown in the above embodiments and modifications.