Wiring board and manufacturing method for wiring board

Abstract

To provide a wiring board and a manufacturing method for the wiring board capable of suppressing the occurrence of moire.SOLUTION: A wiring board includes a mesh wiring layer 20 and a dummy wiring layer 30. A unit pattern 20A of the mesh wiring layer 20 includes first directional wiring 21 extending along a first direction and second directional wiring 22 extending along a second direction. A dummy unit pattern 30A of the dummy wiring layer 30 includes a first dummy wiring portion 31 extending along the first direction and a second dummy wiring portion 32 extending along the second direction. A cutout portion 33 is formed in the dummy unit pattern 30A, and at least one of the position and shape of the cutout portion 33 is different from each other between the dummy unit patterns 30A adjacent to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present disclosure relates to a wiring board and a method for manufacturing a wiring board. [Background technology]

[0002] Currently, mobile terminal devices such as smartphones and tablets are becoming more functional, smaller, thinner, and lighter. These mobile terminal devices use multiple communication bands, so multiple antennas corresponding to the communication bands are required. For example, mobile terminal devices are equipped with multiple antennas such as a telephone antenna, a WiFi (Wireless Fidelity) antenna, a 3G (Generation) antenna, a 4G (Generation) antenna, an LTE (Long Term Evolution) antenna, a Bluetooth (registered trademark) antenna, and an NFC (Near Field Communication) antenna. However, as mobile terminal devices become smaller, the space for mounting the antennas is limited, and the freedom of antenna design is narrowed. In addition, since the antennas are built into a limited space, the radio wave sensitivity is not necessarily satisfactory.

[0003] For this reason, a film antenna that can be mounted in the display area of ​​a mobile terminal device has been developed. This film antenna is a transparent antenna having an antenna pattern formed on a transparent substrate, and the antenna pattern is formed by a mesh-like conductive mesh layer having conductor parts as formed parts of an opaque conductive layer and a large number of openings as non-formed parts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-66610 A [Patent Document 2] Patent No. 5636735 specification [Patent Document 3] Patent No. 5695947 specification Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in a conventional film antenna, one or more mesh antennas are mounted on a transparent substrate, and both an area where an antenna pattern is formed and an area where an antenna pattern is not formed exist on the transparent substrate. In this case, the area where an antenna pattern is formed becomes easily visible due to the existence of the area where an antenna pattern is not formed. For this reason, it is required to make wiring patterns such as an antenna pattern less visible.

[0006] In order to make the wiring pattern less visible, a dummy wiring layer including dummy wiring electrically independent from the wiring pattern may be provided around the wiring pattern. However, in a mobile terminal device or the like equipped with a film antenna, the period of the dummy wiring may interfere with the period of the pixels, causing moire (a light and dark stripe pattern). When moire occurs in this way, the visibility of the image in the mobile terminal device or the like may be reduced.

[0007] An object of the present embodiment is to provide a wiring board and a method for manufacturing the wiring board that can suppress the occurrence of moire. [Means for solving the problem]

[0008] A wiring board according to one embodiment of the present disclosure includes a substrate, a mesh wiring layer disposed on the substrate and including a plurality of wirings, and a dummy wiring layer disposed around the mesh wiring layer and including a plurality of dummy wirings electrically independent from the wirings, wherein the substrate has a transmittance of 85% or more for light having a wavelength of 400 nm or more and 700 nm or less, the mesh wiring layer is composed of a predetermined unit pattern arranged repeatedly, the unit pattern including first directional wiring extending along a first direction and second directional wiring extending along a second direction different from the first direction, the dummy wiring layer is composed of a predetermined dummy unit pattern arranged repeatedly, the dummy unit pattern including a first dummy wiring portion extending along the first direction and a second dummy wiring portion extending along the second direction, a cutout portion is formed in the dummy unit pattern, and at least one of the position and the shape of the cutout portion is different from each other in the dummy unit patterns adjacent to each other.

[0009] In the wiring board according to the embodiment of the present disclosure, in the dummy wiring layer, a difference in aperture ratio between adjacent 500 μm square regions may be within 0.2%.

[0010] In the wiring board according to the embodiment of the present disclosure, in the dummy unit pattern, the first dummy wiring portion and the second dummy wiring portion may be spaced apart from each other.

[0011] In the wiring board according to the embodiment of the present disclosure, in the dummy unit patterns adjacent to each other, the first dummy wiring portions and the second dummy wiring portions may be spaced apart from each other.

[0012] In the wiring board according to the embodiment of the present disclosure, the dummy unit pattern may include a plurality of the cutout portions.

[0013] In the wiring board according to the embodiment of the present disclosure, in the dummy unit patterns adjacent to each other, the first dummy wiring portion and the second dummy wiring portion may have the same total length.

[0014] In the wiring board according to the embodiment of the present disclosure, an additional pattern may be disposed in the dummy wiring layer at a distance from the dummy wiring.

[0015] In the wiring board according to the embodiment of the present disclosure, the dummy unit patterns may be repeatedly arranged in parallel in the first direction and the second direction.

[0016] The wiring board according to the embodiment of the present disclosure may have a radio wave transmission and reception function.

[0017] A method for manufacturing a wiring board according to one embodiment of the present disclosure includes the steps of preparing a substrate, and forming on the substrate a mesh wiring layer including a plurality of wirings, and a dummy wiring layer including a plurality of dummy wirings arranged around the mesh wiring layer and electrically independent from the wirings, wherein the substrate has a transmittance of 85% or more for light having a wavelength of 400 nm or more and 700 nm or less, the mesh wiring layer is composed of a predetermined unit pattern arranged repeatedly, the unit pattern including first directional wiring extending along a first direction and second directional wiring extending along a second direction different from the first direction, the dummy wiring layer is composed of a predetermined dummy unit pattern arranged repeatedly, the dummy unit pattern including a first dummy wiring portion extending along the first direction and a second dummy wiring portion extending along the second direction, a cutout portion is formed in the dummy unit pattern, and at least one of the position and the shape of the cutout portion is different from each other in the dummy unit patterns adjacent to each other. Effect of the Invention

[0018] According to the embodiments of the present disclosure, the occurrence of moire can be suppressed. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a plan view showing a wiring board according to the present embodiment. [Diagram 2] FIG. 2 is an enlarged plan view showing the wiring board according to the present embodiment (an enlarged view of a portion II in FIG. 1). [Diagram 3] FIG. 3 is a cross-sectional view showing the wiring board according to the present embodiment (a cross-sectional view taken along line III-III in FIG. 2). [Figure 4] FIG. 4 is a cross-sectional view showing the wiring board according to the present embodiment (a cross-sectional view taken along line IV-IV in FIG. 2). [Diagram 5] FIG. 5 is a cross-sectional view showing the wiring board according to the present embodiment (a cross-sectional view taken along line VV in FIG. 2). [Figure 6] 6(a)-(f) are cross-sectional views showing the method for manufacturing the wiring board according to the present embodiment. [Figure 7] FIG. 7 is a plan view showing the image display device according to the present embodiment. [Figure 8] FIG. 8 is a plan view showing a modified example of the wiring board according to the present embodiment. [Figure 9] FIG. 9 is a plan view showing a modified example of the wiring board according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] First, the first embodiment will be described with reference to Figures 1 to 7. Figures 1 to 7 are diagrams showing the first embodiment.

[0021] The figures shown below are schematic. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, it is possible to carry out appropriate changes within the scope of the technical idea. In each of the figures shown below, the same parts are given the same symbols, and some detailed explanations may be omitted. In addition, the numerical values ​​such as dimensions of each member and the material names 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 that specify shapes and geometric conditions, such as parallel, orthogonal, and vertical, are intended to include substantially the same state in addition to their strict meanings.

[0022] In this embodiment, the "X direction" is a direction perpendicular to the longitudinal direction of the mesh wiring layer and perpendicular to the direction of the length corresponding to the frequency band of the first directional wiring. The "Y direction" is a direction perpendicular to the X direction and parallel to the longitudinal direction of the mesh wiring layer and parallel to the direction of the length corresponding to the frequency band of the first directional wiring. 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. The "front surface" refers to a surface on the positive side of the Z direction, on which the first directional wiring is provided with respect to the board. The "back surface" refers to a surface on the negative side of the Z direction, on the opposite side to the surface on which the first directional wiring is provided with respect to the board. In this embodiment, the mesh wiring layer 20 is described as having a radio wave transmitting and receiving function (function as an antenna), but the mesh wiring layer 20 does not have to have a radio wave transmitting and receiving function (function as an antenna).

[0023] [Wiring board configuration] The configuration of the wiring board according to the present embodiment will be described with reference to Figures 1 to 5. Figures 1 to 5 are diagrams showing the wiring board according to the present embodiment.

[0024] 1, a wiring board 10 according to the present embodiment is disposed on, for example, a display of an image display device. Such wiring board 10 includes a transparent substrate 11, a mesh wiring layer 20 disposed on substrate 11, and a dummy wiring layer 30 disposed around mesh wiring layer 20 on substrate 11. A power supply unit 40 is electrically connected to mesh wiring layer 20.

[0025] Of these, the substrate 11 is substantially rectangular in plan view, with its longitudinal direction parallel to the Y direction and its lateral direction parallel to the X direction. The substrate 11 is transparent and substantially flat, with its thickness being substantially uniform overall. The length L1 of the substrate 11 in the longitudinal direction (Y direction) can be selected, for example, from 20 mm to 500 mm, preferably from 100 mm to 200 mm, and the length L2 of the substrate 11 in the lateral direction (X direction) can be selected, for example, from 20 mm to 500 mm, preferably from 50 mm to 100 mm. The corners of the substrate 11 may each be rounded.

[0026] The material of the substrate 11 may be any material that has 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, an organic insulating material such as a polyester resin such as polyethylene terephthalate, an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, a polyimide resin, a polyolefin resin such as a cycloolefin polymer, or a cellulose resin material such as triacetyl cellulose may be preferably used. Alternatively, as the material of the substrate 11, an organic insulating material such as a cycloolefin polymer (for example, ZF-16 manufactured by Nippon Zeon Co., Ltd.) or a polynorbornene polymer (manufactured by Sumitomo Bakelite Co., Ltd.) may be used. In addition, as the material of the substrate 11, glass, ceramics, etc. may be appropriately selected according to the application. Note that, although an example of the substrate 11 constituted by a single layer is illustrated, the present invention is not limited thereto, and the substrate 11 may have a structure in which a plurality of base materials or layers are laminated. In addition, the substrate 11 may be in the form of a film or a plate. For this reason, the thickness of the substrate 11 is not particularly limited and can be selected appropriately depending on the application. As an example, the thickness T1 (length in the Z direction, see FIG. 3) of the substrate 11 can be in the range of, for example, 10 μm or more and 200 μm or less.

[0027] The dielectric loss tangent of the substrate 11 may be 0.002 or less, and preferably 0.001 or less. The dielectric loss tangent of the substrate 11 has no particular lower limit, but may be greater than 0. When the dielectric loss tangent of the substrate 11 is in the above range, the loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves can be reduced, particularly when the electromagnetic waves (e.g., millimeter waves) transmitted and received by the mesh wiring layer 20 are high frequency. The lower limit of the dielectric loss tangent of the substrate 11 is not particularly limited. The dielectric constant of the substrate 11 is not particularly limited, but may be 2.0 or more and 10.0 or less.

[0028] The dielectric loss tangent of the substrate 11 can be measured in accordance with IEC 62562. Specifically, first, a test piece is prepared by cutting out a portion of the substrate 11 where the mesh wiring layer 20 is not formed. Alternatively, the substrate 11 on which the mesh wiring layer 20 is formed may be cut out, and the mesh wiring layer 20 may be removed by etching or the like. The dimensions of the test piece are 10 mm to 20 mm in width and 50 mm to 100 mm in length. Next, the dielectric loss tangent is measured in accordance with IEC 62562. The dielectric constant and dielectric loss tangent of the substrate 11 can also be measured in accordance with ASTM D150.

[0029] The substrate 11 may have a visible light transmittance (light having a wavelength of 400 nm or more and 700 nm or less) of 85% or more, and preferably 90% or more. There is no particular upper limit to the visible light transmittance of the substrate 11, but it may be, for example, 100% or less. By setting the visible light transmittance of the substrate 11 within the above range, the transparency of the wiring substrate 10 can be increased, and the display 91 (described later) of the image display device 90 can be easily viewed. Visible light refers to light having a wavelength of 400 nm to 700 nm. The visible light transmittance of 85% or more means that when the absorbance of the substrate 11 is measured using a known spectrophotometer (for example, a spectrometer V-670 manufactured by JASCO Corporation), the transmittance is 85% or more in the entire wavelength range of 400 nm to 700 nm.

[0030] 1, there are a plurality (three) of mesh wiring layers 20 on a substrate 11, each corresponding to a different frequency band. a The lengths L of the mesh wiring layer 20 are different from each other and correspond to specific frequency bands. ais longer. When the wiring board 10 is disposed on, for example, a display 91 (see FIG. 7 described later) of an image display device 90, each mesh wiring layer 20 may have a radio wave transmission / reception function. In this case, each mesh wiring layer 20 may correspond to any of a telephone antenna, a WiFi antenna, a 3G antenna, a 4G antenna, a 5G antenna, an LTE antenna, an Bluetooth (registered trademark) antenna, an NFC antenna, and the like. Alternatively, when the wiring board 10 does not have a radio wave transmission / reception function, each mesh wiring layer 20 may perform functions such as hovering (a function that allows a user to operate the display without directly touching it), fingerprint authentication, a heater, and a noise cut (shield). In addition, the mesh wiring layer 20 may not be present on the entire surface of the substrate 11, but may be present only in a partial area on the substrate 11.

[0031] Each mesh wiring layer 20 has a substantially rectangular shape in a plan view. The longitudinal direction of each mesh wiring layer 20 is parallel to the Y direction, and the lateral direction of each mesh wiring layer 20 is parallel to the X direction. The length L of each mesh wiring layer 20 in the longitudinal direction (Y direction) is a can be selected, for example, in the range of 1 mm to 100 mm, and the width W a The length L of the mesh wiring layer 20 can be selected, for example, in the range of 1 mm to 10 mm. In particular, the mesh wiring layer 20 may be a millimeter wave antenna. When the mesh wiring layer 20 is a millimeter wave antenna, the length L of the mesh wiring layer 20 can be selected, for example, in the range of 1 mm to 10 mm. a can be selected in the range of 1 mm or more and 10 mm or less, more preferably 1.5 mm or more and 5 mm or less.

[0032] The mesh wiring layer 20 is composed of a predetermined unit pattern 20A repeatedly arranged along a first direction (for example, the Y direction). The unit pattern 20A is also repeatedly arranged along a second direction (for example, the X direction) different from the first direction. In other words, the mesh wiring layer 20 has metal wires formed in a lattice or mesh shape, and has a uniform repeated pattern in the X direction and the Y direction. That is, as shown in FIG. 2, the mesh wiring layer 20 is composed of repeated L-shaped unit patterns 20A (shaded parts in FIG. 2) each of which is composed of a part extending in the X direction (a part of the second direction wiring 22 described later) and a part extending in the Y direction (a part of the first direction wiring 21 described later). In other words, the unit pattern 20A includes a first direction wiring 21 described later that extends along the first direction and a second direction wiring 22 described later that extends along the second direction.

[0033] As shown in FIG. 2, each mesh wiring layer 20 includes a plurality of first directional wirings (antenna wiring (wiring)) 21 that function as an antenna, and a plurality of second directional wirings (antenna connecting wiring) 22 that connect the plurality of first directional wirings 21. Specifically, the plurality of first directional wirings 21 and the plurality of second directional wirings 22 are integrated as a whole to form a regular lattice shape or mesh shape. Each first directional wiring 21 extends in a direction corresponding to the frequency band of the antenna (longitudinal direction, Y direction), and each second directional wiring 22 extends in a direction perpendicular to the first directional wiring 21 (width direction, X direction). The first directional wiring 21 has a length L corresponding to a predetermined frequency band. a (See FIG. 1 for the length of the mesh wiring layer 20 described above), and thus mainly functions as an antenna. On the other hand, the second directional wiring 22 plays a role in preventing problems such as the first directional wiring 21 being broken or the first directional wiring 21 and the power supply unit 40 being no longer electrically connected to each other by connecting these first directional wirings 21 together.

[0034] In each mesh wiring layer 20, a plurality of openings 23 are formed by being surrounded by adjacent first direction wires 21 and adjacent second direction wires 22. The first direction wires 21 and the second direction wires 22 are arranged at equal intervals. That is, the plurality of first direction wires 21 are arranged at equal intervals, and the pitch P1 (see FIG. 2) can be set to, for example, a range of 0.01 mm to 1 mm. The plurality of second direction wires 22 are arranged at equal intervals, and the pitch P2 (see FIG. 2) can be set to, for example, a range of 0.01 mm to 1 mm. In this way, the plurality of first direction wires 21 and the plurality of second direction wires 22 are arranged at equal intervals, so that the size of the openings 23 in each mesh wiring layer 20 does not vary, and the mesh wiring layer 20 can be made difficult to see with the naked eye. The pitch P1 of the first direction wires 21 is equal to the pitch P2 of the second direction wires 22. Therefore, each opening 23 is approximately square in plan view, and the substrate 11 having transparency 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 increased. The length L3 (see FIG. 2) of one side of each opening 23 can be set to, for example, a range of 0.01 mm or more and 1 mm or less. The first direction wirings 21 and the second direction wirings 22 are orthogonal to each other, but are not limited to this, and may intersect each other at an acute angle or an obtuse angle. Each opening 23 may have a shape such as approximately rectangular in plan view. Furthermore, the shape of the opening 23 is preferably the same shape and size over the entire surface, but it does not have to be uniform over the entire surface, and may be changed depending on the location.

[0035] As shown in FIG. 3, each of the first direction wirings 21 has a cross section (X-direction cross section) perpendicular to its longitudinal direction of approximately rectangular or square. In this case, the cross-sectional shape of the first direction wirings 21 is approximately uniform along the longitudinal direction (Y-direction) of the first direction wirings 21. Also, as shown in FIG. 4, the cross-sectional shape (Y-direction cross section) of each of the second direction wirings 22 perpendicular to the longitudinal direction of the second direction wirings 22 is approximately rectangular or square, and is approximately the same as the cross-sectional shape (X-direction cross section) of the first direction wirings 21 described above. In this case, the cross-sectional shape of the second direction wirings 22 is approximately uniform along the longitudinal direction (X-direction) of the second direction wirings 22. The cross-sectional shapes of the first direction wirings 21 and the second direction wirings 22 do not necessarily have to be approximately rectangular or square, and may be, for example, approximately trapezoidal in which the front side (Z-direction positive side) is narrower than the back side (Z-direction negative side), or may be shaped such that the side surfaces located on both sides in the width direction are curved.

[0036] In this embodiment, the line width W1 (length in the X direction, see FIG. 3) of the first directional wire 21 and the line width W2 (length in the Y direction, see FIG. 4) of the second directional wire 22 are not particularly limited and can be appropriately selected according to the application. For example, the line width W1 of the first directional wire 21 can be selected in the range of 0.1 μm to 5.0 μm, and preferably 0.2 μm to 2.0 μm. The line width W2 of the second directional wire 22 can be selected in the range of 0.1 μm to 5.0 μm, and preferably 0.2 μm to 2.0 μm. By setting the line width W1 of the first directional wire 21 to 5.0 μm or less, even if moire occurs, the density of the moire can be reduced, and by setting the line width W1 to 2.0 μm or less, the density of the moire can be further reduced. Similarly, by making the line width W2 of the second direction wiring 22 5.0 μm or less, even if moire occurs, the density of the moire can be made thin, and by making the line width W2 2.0 μm or less, the density of the moire can be made even thinner.

[0037] Furthermore, the height H1 (length in the Z direction, see FIG. 3) of the first directional wiring 21 and the height H2 (length in the Z direction, see FIG. 4) of the second directional wiring 22 are not particularly limited and can be appropriately selected depending on the application, for example, in the range of 0.1 μm or more and 5.0 μm or less, and preferably 0.2 μm or more and 2.0 μm or less.

[0038] The material of the first directional wiring 21 and the second directional wiring 22 may be any metal material having electrical conductivity. In the present embodiment, the material of the first directional wiring 21 and the second directional wiring 22 is copper, but is not limited to this. The material of the first directional wiring 21 and the second directional wiring 22 may be, for example, a metal material (including an alloy) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel.

[0039] 1 again, the dummy wiring layer 30 is provided so as to surround each mesh wiring layer 20, and is formed so as to surround the entire circumferential area (positive side in the X direction, negative side in the X direction, positive side in the Y direction) of each mesh wiring layer 20 except for the power supply unit 40 side (negative side in the Y direction). In this case, the dummy wiring layer 30 is disposed on the substrate 11 over almost the entire area except for the mesh wiring layer 20 and the power supply unit 40. Unlike the mesh wiring layer 20, this dummy wiring layer 30 does not substantially function as an antenna.

[0040] As shown in FIG. 2, the dummy wiring layer 30 is composed of predetermined dummy unit patterns 30A (combination of the hatched portion and the diagonal line portion in FIG. 2) that are repeatedly arranged. The dummy unit patterns 30A are repeatedly arranged along a first direction (e.g., Y direction) and a second direction (e.g., X direction). In the illustrated example, the dummy unit patterns 30A are L-shaped and repeatedly arranged parallel to the first direction (Y direction) and the second direction (X direction). In other words, the dummy wiring layer 30 is composed of repeated dummy wirings 30a having a predetermined unit pattern. That is, the dummy wiring layer 30 includes a plurality of dummy wirings 30a, and each dummy wiring 30a is electrically independent from the mesh wiring layer 20 (first direction wiring 21) and the power supply unit 40. The plurality of dummy wirings 30a are regularly arranged throughout the dummy wiring layer 30. The dummy wirings 30a are each formed of metal wires in a lattice or mesh shape, and have a uniform repeat pattern in the X and Y directions. That is, as shown in Fig. 2, each dummy wiring 30a includes a first dummy wiring portion 31 extending along a first direction (Y direction) and a second dummy wiring portion 32 extending along a second direction (X direction). Of these, the first dummy wiring portion 31 has a predetermined length L4 (length in the Y direction), and the second dummy wiring portion 32 has a predetermined length L5 (length in the X direction).

[0041] In this embodiment, the dummy wiring 30a has a shape in which a part of the unit pattern 20A of the mesh wiring layer 20 described above is missing. That is, the shape of the dummy wiring 30a is a shape obtained by removing the cutout portion 33 described later from the L-shaped unit pattern 20A of the mesh wiring layer 20. That is, the shape obtained by combining the dummy wiring 30a of the dummy wiring layer 30 and the cutout portion 33 corresponds to the lattice shape or mesh shape forming the mesh wiring layer 20. In this way, since the dummy wiring 30a of the dummy wiring layer 30 has a shape in which a part of the unit pattern 20A of the mesh wiring layer 20 is missing, it is possible to make it difficult to visually recognize the difference between the mesh wiring layer 20 and the dummy wiring layer 30, and it is possible to make the mesh wiring layer 20 arranged on the substrate 11 difficult to see.

[0042] In FIG. 2, the mesh wiring layer 20 and the dummy wiring layer 30 are adjacent to each other in the Y direction. In the vicinity of the boundary between the mesh wiring layer 20 and the dummy wiring layer 30, the first dummy wiring portion 31 is formed on the extension of the first direction wiring 21. Therefore, in the Y direction, the difference between the mesh wiring layer 20 and the dummy wiring layer 30 is difficult to visually recognize. In addition, the first dummy wiring portion 31 is parallel to the first direction wiring 21 of the unit pattern 20A of the mesh wiring layer 20. In this way, since the first dummy wiring portion 31 is parallel to the first direction wiring 21, even if the first dummy wiring portion 31 of the dummy unit pattern 30A is irregularly arranged as described later, it is possible to effectively suppress glare caused by light reflection.

[0043] Although not shown, the mesh wiring layer 20 and the dummy wiring layer 30 are adjacent to each other in the X direction. In the vicinity of the boundary between the mesh wiring layer 20 and the dummy wiring layer 30, the second dummy wiring portion 32 is formed on the extension of the second direction wiring 22. Therefore, in the X direction, the difference between the mesh wiring layer 20 and the dummy wiring layer 30 is difficult to visually recognize. In addition, the second dummy wiring portion 32 is parallel to the second direction wiring 22 of the unit pattern 20A of the mesh wiring layer 20. In this way, since the second dummy wiring portion 32 is parallel to the second direction wiring 22, even if the second dummy wiring portion 32 of the dummy unit pattern 30A is irregularly arranged as described later, it is possible to effectively suppress glare caused by light reflection.

[0044] As shown in Fig. 5, the first dummy wiring portion 31 of each dummy wiring 30a has a cross section (X-direction cross section) perpendicular to its longitudinal direction (Y-direction) in a substantially rectangular or square shape. Also, as shown in Fig. 4, the second dummy wiring portion 32 of each dummy wiring 30a has a cross section (Y-direction cross section) perpendicular to its longitudinal direction (X-direction) in a substantially rectangular or square shape. In this case, the cross-sectional shape of the first dummy wiring portion 31 is substantially the same as the cross-sectional shape of the first-direction wiring 21, and the cross-sectional shape of the second dummy wiring portion 32 is substantially the same as the cross-sectional shape of the second-direction wiring 22.

[0045] In this embodiment, the line width W3 (length in the X direction, see FIG. 5) of the first dummy wiring portion 31 is approximately the same as the line width W1 of the first directional wiring 21, and the line width W4 (length in the Y direction, see FIG. 4) of the second dummy wiring portion 32 is approximately the same as the line width W2 of the second directional wiring 22. In addition, the height H3 (length in the Z direction, see FIG. 5) of the first dummy wiring portion 31 and the height H4 (length in the Z direction, see FIG. 4) of the second dummy wiring portion 32 are also approximately the same as the height H1 of the first directional wiring 21 and the height H2 of the second directional wiring 22, respectively.

[0046] Here, in this embodiment, the dummy unit pattern 30A has a notch portion 33. In addition, at least one of the position and the shape of the notch portion 33 in the adjacent dummy unit patterns 30A is different from each other. In other words, in the dummy unit pattern 30A, the notch portion 33 is formed randomly (irregularly). This allows the first dummy wiring portion 31 and the second dummy wiring portion 32 of the dummy unit pattern to be arranged irregularly. Therefore, the pitch of the moire generated due to the regularity (periodicity) of the dummy unit pattern 30A and the regularity (periodicity) of the pixels (not shown) of the image display device 90 described later can be reduced to a level that cannot be seen by the naked eye.

[0047] In the illustrated example, the positions and shapes of the cutout portions 33 of the adjacent dummy unit patterns 30A are different from each other. That is, the lengths L4 of the first dummy wiring portions 31 of the adjacent dummy unit patterns 30A are different from each other. Furthermore, the lengths L5 of the second dummy wiring portions 32 of the adjacent dummy unit patterns 30A are different from each other.

[0048] Furthermore, the dummy unit pattern 30A may have a plurality of cutout portions 33 formed therein. This allows the first dummy wiring portion 31 and the second dummy wiring portion 32 to be arranged more irregularly. In this case, in one dummy unit pattern 30A, the cutout portion 33 may be formed so as to divide the first dummy wiring portion 31 (the second dummy wiring portion 32). Note that the dummy wiring layer 30 may be provided with a dummy unit pattern 30A in which a plurality of cutout portions 33 are formed and a dummy unit pattern 30A in which a single cutout portion 33 is formed.

[0049] In the dummy unit pattern 30A, the first dummy wiring portion 31 and the second dummy wiring portion 32 may be spaced apart from each other. That is, a notch 33 may be formed between the first dummy wiring portion 31 and the second dummy wiring portion 32. This allows the first dummy wiring portion 31 and the second dummy wiring portion 32 to be arranged more irregularly.

[0050] Furthermore, in adjacent dummy unit patterns 30A, the first dummy wiring portions 31 and the second dummy wiring portions 32 may be spaced apart from each other. That is, the first dummy wiring portion 31 of one dummy unit pattern 30A and the first dummy wiring portion 31 of the other dummy unit pattern 30A adjacent to the one dummy unit pattern 30A may be spaced apart from each other. Similarly, the second dummy wiring portion 32 of one dummy unit pattern 30A and the second dummy wiring portion 32 of the other dummy unit pattern 30A adjacent to the one dummy unit pattern 30A may be spaced apart from each other. In this case as well, the first dummy wiring portions 31 and the second dummy wiring portions 32 can be arranged more irregularly.

[0051] Furthermore, in the mutually adjacent dummy unit patterns 30A, it is preferable that the total lengths (L4+L5) of the first dummy wiring portion 31 and the second dummy wiring portion 32 are equal to each other. This can suppress the occurrence of variations in the aperture ratio, which will be described later, in the dummy wiring layer 30. This can make the dummy wiring layer 30 difficult to see with the naked eye.

[0052] The material of the dummy wirings 30 a of the dummy wiring layer 30 can be the same metal material as the material of the first directional wirings 21 and the material of the second directional wirings 22 .

[0053] In the present embodiment, the mesh wiring layer 20 and the dummy wiring layer 30 each have a predetermined aperture ratio. The aperture ratio of the mesh wiring layer 20 and the dummy wiring layer 30 can be set to, for example, in the range of 85% to 99.9%.

[0054] The overall aperture ratio of the mesh wiring layer 20 and the dummy wiring layer 30 (the combined aperture ratio of the mesh wiring layer 20 and the dummy wiring layer 30) can be set to, for example, a range of 87% or more and less than 100%. By setting the overall aperture ratio of the wiring board 10 to this range, the conductivity and transparency of the wiring board 10 can be ensured.

[0055] Furthermore, in the dummy wiring layer 30, the difference in the aperture ratio between adjacent 500 μm square regions is preferably within 0.2%, which makes it possible to make the dummy wiring layer 30 difficult to see with the naked eye.

[0056] The opening ratio refers to the percentage of the area of ​​the opening region (the region where no metal parts such as the first directional wiring 21, the second directional wiring 22, the dummy wiring 30a, etc. are present and the substrate 11 is exposed) in a unit area of ​​a specified region (the mesh wiring layer 20, the dummy wiring layer 30, or the mesh wiring layer 20 and the dummy wiring layer 30).

[0057] Referring again to FIG. 1, the power supply unit 40 is electrically connected to the mesh wiring layer 20. The power supply unit 40 is made of a conductive thin plate 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 the longitudinal end (the end on the negative side in the Y direction) of the substrate 11. The material of the power supply unit 40 may be, for example, a metal material (including an alloy) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel. When the wiring substrate 10 is incorporated into the image display device 90 (see FIG. 7), the power supply unit 40 is electrically connected to the wireless communication circuit 92 of the image display device 90. The power supply unit 40 is provided on the surface of the substrate 11, but is not limited thereto, and a part or the whole of the power supply unit 40 may be located outside the periphery of the substrate 11.

[0058] [Method of manufacturing wiring board] Next, a method for manufacturing a wiring board according to the present embodiment will be described with reference to Figures 6(a) to 6(f). Figures 6(a) to 6(f) are cross-sectional views showing the method for manufacturing a wiring board according to the present embodiment.

[0059] First, as shown in FIG. 6(a), a transparent substrate 11 is prepared.

[0060] Next, on the substrate 11, a mesh wiring layer 20 including a plurality of first directional wirings 21 and a dummy wiring layer 30 including a plurality of dummy wirings 30a arranged around the mesh wiring layer 20 and electrically independent from the first directional wirings 21 are formed.

[0061] 6(b), first, metal foil 51 is laminated on substantially the entire surface of substrate 11. In this embodiment, metal foil 51 may have a thickness of 0.1 μm or more and 5.0 μm or less. In this embodiment, metal foil 51 may contain copper.

[0062] 6(c), a photocurable insulating resist 52 is applied to almost the entire surface of the metal foil 51. As the photocurable insulating resist 52, for example, an organic resin such as an acrylic resin or an epoxy resin can be used.

[0063] 6(d), the insulating layer 54 is formed by photolithography. In this case, the photo-curable insulating resist 52 is patterned by photolithography to form the insulating layer 54 (resist pattern). At this time, the insulating layer 54 is formed so that the metal foil 51 corresponding to the first directional wiring 21 and the second directional wiring 22 is exposed.

[0064] 6(e), metal foil 51 located on the surface of substrate 11 in a portion not covered with insulating layer 54 is removed. At this time, metal foil 51 is etched so that the surface of substrate 11 is exposed by performing a wet treatment using ferric chloride, cupric chloride, a strong acid such as sulfuric acid or hydrochloric acid, a persulfate, hydrogen peroxide, or an aqueous solution of these, or a combination of these.

[0065] 6(f), the insulating layer 54 is removed. In this case, the insulating layer 54 on the metal foil 51 is removed by a wet treatment using a permanganate solution, N-methyl-2-pyrrolidone, an acid or alkaline solution, or a dry treatment using oxygen plasma.

[0066] In this manner, a wiring board 10 is obtained that includes the substrate 11, and the mesh wiring layer 20 and the dummy wiring layer 30 disposed on the substrate 11. In this case, the mesh wiring layer 20 includes first-directional wiring 21 and second-directional wiring 22, and the dummy wiring layer 30 includes dummy wiring 30a.

[0067] [Operation of this embodiment] Next, the operation of this embodiment having the above configuration will be described.

[0068] As shown in FIG. 7, the wiring board 10 is incorporated into 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 mobile terminal devices such as smartphones and tablets. The mesh wiring layer 20 of the wiring board 10 is electrically connected to a wireless communication circuit 92 of the image display device 90 via a power supply unit 40. In this way, radio waves of a predetermined frequency can be transmitted and received via the mesh wiring layer 20, and communication can be performed using the image display device 90. The dummy wiring layer 30 is separated from the mesh wiring layer 20 and is electrically independent. Therefore, even if the dummy wiring layer 30 is provided, the transmission and reception of radio waves is not affected.

[0069] According to this embodiment, wiring board 10 has substrate 11 and mesh wiring layer 20 disposed on substrate 11 and including a plurality of first directional wires 21, and substrate 11 has a transmittance of 85% or more for light having a wavelength of 400 nm or more and 700 nm or less, ensuring the transparency of wiring board 10. As a result, when wiring board 10 is disposed on display 91, display 91 can be viewed through openings 23 of mesh wiring layer 20, and therefore visibility of display 91 is not hindered.

[0070] Moreover, around the mesh wiring layer 20, a dummy wiring layer 30 including a plurality of dummy wirings 30a electrically independent from the first directional wirings 21 is arranged.

[0071] Incidentally, in the image display device 90, the dummy wiring layer 30 of the wiring substrate 10 is disposed so as to overlap with pixels (not shown) of the image display device 90 in the Z direction. For this reason, moire may occur due to the regularity (periodicity) of the dummy unit patterns 30A of the dummy wiring layer 30 and the regularity (periodicity) of the pixels.

[0072] In contrast to this, in this embodiment, a cutout portion 33 is formed in the dummy unit pattern 30A of the dummy wiring layer 30. In addition, at least one of the position and the shape of the cutout portion 33 is different between adjacent dummy unit patterns 30A. As a result, when viewed from the Z direction, the first dummy wiring portion 31 and the second dummy wiring portion 32 of the dummy unit pattern 30A and the pixels are irregularly arranged. Therefore, the pitch of the moire generated due to the regularity (periodicity) of the dummy unit pattern 30A and the regularity (periodicity) of the pixels can be made small to an extent that it cannot be seen by the naked eye.

[0073] Moreover, the unit pattern 20A includes the first directional wiring 21 extending along the Y direction (first direction) and the second directional wiring 22 extending along the X direction (second direction), and the dummy unit pattern 30A includes the first dummy wiring portion 31 extending along the Y direction (first direction) and the second dummy wiring portion 32 extending along the X direction (second direction). That is, the first directional wiring 21 and the first dummy wiring portion 31 extend along the Y direction, and the second directional wiring 22 and the second dummy wiring portion 32 extend along the X direction. This makes it possible to suppress glare caused by light reflection even when the first dummy wiring portion 31 and the second dummy wiring portion 32 of the dummy unit pattern 30A are irregularly arranged. Moreover, in this embodiment, the first dummy wiring portion 31 and the second dummy wiring portion 32 are parallel to the first directional wiring 21 and the second directional wiring 22. As a result, even if the first dummy wiring portions 31 and the second dummy wiring portions 32 of the dummy unit pattern 30A are irregularly arranged, it is possible to effectively prevent glare caused by light reflection.

[0074] Furthermore, according to this embodiment, in the dummy unit pattern 30A, the first dummy wiring portion 31 and the second dummy wiring portion 32 are spaced apart from each other. That is, a cutout portion 33 is formed between the first dummy wiring portion 31 and the second dummy wiring portion 32. This allows the first dummy wiring portion 31 and the second dummy wiring portion 32 to be arranged more irregularly. This makes it possible to make the generated moire more difficult to visually recognize.

[0075] Furthermore, according to the present embodiment, in adjacent dummy unit patterns 30A, the first dummy wiring portions 31 and the second dummy wiring portions 32 are spaced apart from each other. Even in this case, the first dummy wiring portions 31 and the second dummy wiring portions 32 can be arranged more irregularly, and the generated moire can be made less visible.

[0076] Moreover, according to the present embodiment, the dummy unit pattern 30A is formed with a plurality of cutout portions 33. In this case as well, the first dummy wiring portions 31 and the second dummy wiring portions 32 can be arranged more irregularly, and the generated moire can be made less visible.

[0077] Furthermore, according to this embodiment, in the dummy unit patterns 30A adjacent to each other, the total lengths (L4+L5) of the first dummy wiring portion 31 and the second dummy wiring portion 32 are equal to each other. This makes it possible to suppress variations in the aperture ratio in the dummy wiring layer 30. This makes it possible to make the dummy wiring layer 30 difficult to see with the naked eye.

[0078] Furthermore, according to this embodiment, the dummy unit patterns 30A are repeatedly arranged in parallel in the Y direction (first direction) and the X direction (second direction). This makes it possible to more effectively prevent glare caused by light reflection even when the first dummy wiring portions 31 and the second dummy wiring portions 32 of the dummy unit patterns 30A are irregularly arranged.

[0079] [Variations] Next, modified examples of the image display device and the wiring board will be described. Figures 8 and 9 show one modified example of the wiring board. The modified example shown in Figures 8 and 9 differs in the planar shape of the mesh wiring layer 20, and other configurations are substantially the same as the embodiment shown in Figures 1 to 7 described above. In Figures 8 and 9, the same parts as those in the embodiment shown in Figures 1 to 7 are given the same reference numerals and detailed description will be omitted.

[0080] (First Modification) 8, the first directional wiring 21 and the second directional wiring 22 intersect at an angle (non-right angle), and each opening 23 is formed in a diamond shape in a plan view. The first directional wiring 21 and the second directional wiring 22 are not parallel to either the X direction or the Y direction, but either one of the first directional wiring 21 and the second directional wiring 22 may be parallel to the X direction or the Y direction.

[0081] Furthermore, the first dummy wiring portions 31 of the dummy wiring layer 30 may extend parallel to the first directional wirings 21. Similarly, the second dummy wiring portions 32 of the dummy wiring layer 30 may extend parallel to the second directional wirings 22.

[0082] In this modification, a cutout portion 33 is also formed in the dummy unit pattern 30A of the dummy wiring layer 30. In the dummy unit patterns 30A adjacent to each other, at least one of the position and the shape of the cutout portion 33 is different from each other. As a result, when viewed from the Z direction, the first dummy wiring portion 31 and the second dummy wiring portion 32 of the dummy unit pattern and the pixels are irregularly arranged. Therefore, the pitch of the moire generated due to the regularity (periodicity) of the dummy unit pattern 30A and the regularity (periodicity) of the pixels can be reduced to a level that cannot be seen by the naked eye.

[0083] (Second Modification) In FIG. 9, in this modification, an additional pattern 34 is disposed in the dummy wiring layer 30, spaced apart from the dummy wiring 30a of the dummy wiring layer 30. In this case, the additional pattern 34 is disposed away from the first dummy wiring parts 31 and the second dummy wiring parts 32 in both the X direction and the Y direction. In this case, each additional pattern 34 extends linearly in parallel to the first dummy wiring parts 31 or the second dummy wiring parts 32. In addition, a plurality (two) additional patterns 34 are disposed for one dummy wiring 30a. It is preferable that the total area of ​​the plurality (two) additional patterns 34 is close to the area of ​​the cutout portion 33 of each dummy wiring 30a. The material of the additional pattern 34 can be the same metal material as the material of the dummy wiring 30a.

[0084] In this way, by arranging the additional pattern 34 in the dummy wiring layer 30, the difference between the aperture ratio of the dummy wiring layer 30 and the aperture ratio of the mesh wiring layer 20 can be made close to 0. Specifically, the difference can be set to a range of 0% to 1%. This makes it possible to make the boundary between the mesh wiring layer 20 and the dummy wiring layer 30 unclear, and makes it difficult to recognize the mesh wiring layer 20 with the naked eye.

[0085] Although not shown, each additional pattern 34 may extend linearly and non-parallel to the first dummy wiring portion 31 or the second dummy wiring portion 32. Also, the additional pattern 34 may have a dot shape (point shape) in a plan view without extending linearly.

[0086] It is also possible to combine the multiple components disclosed in the above embodiment and each modification as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiment and each modification. [Explanation of symbols]

[0087] 10 Wiring board 11 Substrate 20 Mesh wiring layer 20A unit pattern 21 1st direction wiring 22 2nd direction wiring 30 Dummy wiring layer 30A Dummy unit pattern 30a Dummy wiring 31 First dummy wiring section 32 Second dummy wiring section 33 Cutout 34 Additional Patterns

Claims

1. A wiring board, A transparent substrate; a mesh wiring layer disposed on the substrate and including a plurality of wirings; a dummy wiring layer including a plurality of dummy wirings electrically independent from the wirings; the mesh wiring layer is composed of unit patterns arranged repeatedly, the dummy wiring layer is composed of repeatedly arranged dummy unit patterns, a notch portion is formed in the dummy unit pattern, At least one of the position and the shape of the cutout portion of the adjacent dummy unit patterns is different from each other.

2. 2. The wiring board according to claim 1, wherein a difference in aperture ratio between adjacent 500 [mu]m square regions in the dummy wiring layer is within 0.2%.

3. the dummy unit pattern includes a first dummy wiring portion extending along a first direction and a second dummy wiring portion extending along a second direction different from the first direction; 3. The wiring board according to claim 1, wherein in the dummy unit pattern, the first dummy wiring portion and the second dummy wiring portion are spaced apart from each other.

4. The wiring board according to claim 3 , wherein in the dummy unit patterns adjacent to each other, the first dummy wiring portions and the second dummy wiring portions are spaced apart from each other.

5. 5. The wiring board according to claim 3, wherein the dummy unit pattern has a plurality of the notches formed therein.

6. 6. The wiring board according to claim 3, wherein total lengths of the first dummy wiring portion and the second dummy wiring portion are equal in the dummy unit patterns adjacent to each other.

7. 7. The wiring board according to claim 3, wherein an additional pattern is disposed in the dummy wiring layer and spaced apart from the dummy wirings.

8. The wiring board according to claim 7 , wherein the additional pattern extends non-parallel to the first dummy wiring portion or the second dummy wiring portion.

9. The wiring board according to claim 3 , wherein the dummy unit patterns are repeatedly arranged in parallel to the first direction and the second direction.

10. The wiring board according to claim 1 , having a radio wave transmitting and receiving function.

11. A method for manufacturing a wiring board, comprising: Providing a transparent substrate; forming, on the substrate, a mesh wiring layer including a plurality of wirings, and a dummy wiring layer including a plurality of dummy wirings electrically independent from the wirings; the mesh wiring layer is composed of unit patterns arranged repeatedly, the dummy wiring layer is composed of repeatedly arranged dummy unit patterns, a notch portion is formed in the dummy unit pattern, A method for manufacturing a wiring board, wherein at least one of the position and the shape of the cutout portions of the dummy unit patterns adjacent to each other is different from each other.

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