Wiring board and method for manufacturing the same

Abstract

To provide a wiring board and a manufacturing method thereof that can prevent a protective layer and a feeding portion from peeling off from each other.SOLUTION: A wiring board 10 includes a transparent board 11, a wiring pattern region 20 that is located on the board 11 and contains a plurality of wirings 21, and a feeding portion 40 electrically connected to the wiring pattern region 20, and the feeding portion 40 includes an inner region 41 where irregularities 41a are formed, and an outer region 42 provided around the inner region 41 and having no irregularities or having irregularities 42a smaller than the irregularities 41a of the inner region 41.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Currently, mobile terminal devices such as smartphones and tablets are becoming increasingly sophisticated, smaller, thinner, and lighter. These mobile terminal devices use multiple communication bands, requiring multiple antennas corresponding to the communication bands. For example, mobile terminal devices are equipped with multiple antennas, such as a telephone antenna, a Wi-Fi (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 available for antenna installation is limited, limiting the degree of freedom in antenna design. Furthermore, because antennas are built into a limited space, radio wave sensitivity is not always satisfactory.

[0003] For this reason, film antennas that can be mounted in the display area of ​​mobile terminal devices have been developed. These film antennas are transparent antennas in which an antenna pattern is formed on a transparent substrate, and the antenna pattern is formed by a mesh-like conductive mesh layer that consists of conductor portions as formed portions of an opaque conductive layer and numerous openings as non-formed portions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-66610 [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] In a film antenna, it is preferable to cover the conductive mesh layer and the power supply part with a protective layer to protect them. However, since the power supply part that supplies electricity to the conductive mesh layer is generally made of a uniform metal plate member with no gaps over the entire surface, there is a risk that the protective layer covering the power supply part and the power supply part may peel off.

[0006] An object of the present embodiment is to provide a wiring board and a method for manufacturing the wiring board that can prevent the protective layer and the power supply portion from peeling off from each other. [Means for solving the problem]

[0007] A wiring board according to one embodiment of the present disclosure is a wiring board comprising: a transparent substrate; a wiring pattern area disposed on the substrate and including a plurality of wirings; and a power supply section electrically connected to the wiring pattern area, wherein the power supply section has an inner area in which irregularities are formed; and an outer area provided around the inner area and in which irregularities are either not formed or which are formed with irregularities smaller than those of the inner area.

[0008] In the wiring board according to the embodiment of the present disclosure, the surface of the inner region may have a surface roughness Ra of 0.2 μm or more and 100 μm or less.

[0009] In the wiring board according to the embodiment of the present disclosure, the outer region may have smaller irregularities than the inner region, and the outer region may have a surface roughness Ra of 10 nm or more and 100 nm or less.

[0010] In the wiring board according to the embodiment of the present disclosure, the width of the outer region may be equal to or greater than the skin depth of the power supply portion.

[0011] In the wiring board according to the embodiment of the present disclosure, the width of the outer region may be as follows:

[0012] In the wiring board according to the embodiment of the present disclosure, a protective layer may be formed on the board so as to cover the wiring pattern area and the power supply portion.

[0013] The wiring board according to the embodiment of the present disclosure may have a radio wave transmission and reception function.

[0014] A method for manufacturing a wiring board according to one embodiment of the present disclosure is a method for manufacturing a wiring board, comprising the steps of preparing a transparent substrate, and forming, on the substrate, a wiring pattern area including a plurality of wires, and a power supply section electrically connected to the wiring pattern area, wherein the power supply section has an inner area having an unevenness formed therein, and an outer area provided around the inner area and having no unevenness or having unevenness smaller than the unevenness of the inner area.

[0015] In the method for manufacturing a wiring board according to the embodiment of the present disclosure, the projections and recesses in the inner region may be formed by embossing. [Effects of the Invention]

[0016] According to the embodiment of the present disclosure, it is possible to prevent the protective layer and the power supply part from peeling off from each other. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a plan view showing a wiring board according to an embodiment. [Figure 2] FIG. 2 is an enlarged plan view (enlarged view of part II in FIG. 1) showing the wiring board according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view (a cross-sectional view taken along line III-III in FIG. 2) showing the wiring board according to the embodiment. [Figure 4]FIG. 4 is a cross-sectional view (a cross-sectional view taken along line IV-IV in FIG. 2) showing the wiring board according to the embodiment. [Figure 5] FIG. 5 is an enlarged plan view (enlarged view of part V in FIG. 1) showing the wiring board according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view (a cross-sectional view taken along line VI-VI in FIG. 5) showing the wiring board according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view (cross-sectional view taken along line VII-VII in FIG. 5) showing the wiring board according to the embodiment. [Figure 8] 8(a) to 8(f) are cross-sectional views showing a method for manufacturing a wiring board according to one embodiment. [Figure 9] 9(a) to 9(d) are cross-sectional views showing a method for manufacturing a wiring board according to one embodiment. [Figure 10] FIG. 10 is a plan view showing an image display device according to an embodiment. [Figure 11] FIG. 11 is a cross-sectional view (corresponding to FIG. 6) showing a modified example of the wiring board according to the embodiment. [Figure 12] FIG. 12 is a plan view (corresponding to FIG. 5) showing a modified example of the wiring board according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] First, one embodiment will be described with reference to Figures 1 to 10. Figures 1 to 10 are diagrams showing this embodiment.

[0019] The figures shown below are schematic illustrations. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, appropriate modifications can be made within the scope of the technical concept. In the figures shown below, identical parts are denoted by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each component described in this specification are examples of embodiments, and are not limited to these and may be selected and used as appropriate. In this specification, terms specifying shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are intended to include substantially the same state in addition to their strict meanings.

[0020] In this embodiment, the "X direction" refers to a direction parallel to one side of the substrate. The "Y direction" refers to a direction perpendicular to the X direction and parallel to another side of the substrate. The "Z direction" refers to a direction perpendicular to both the X and Y directions and parallel to the thickness direction of the wiring substrate. The "front surface" refers to the surface on the positive side of the Z direction, on which wiring is provided relative to the substrate. The "back surface" refers to the surface on the negative side of the Z direction, opposite to the surface on which wiring is provided relative to the substrate. Note that in this embodiment, the case where the wiring pattern region 20 is an antenna pattern region 20 having a radio wave transmitting and receiving function (functioning as an antenna) will be described as an example, but the wiring pattern region 20 does not necessarily have a radio wave transmitting and receiving function (functioning as an antenna).

[0021] [Wiring board configuration] The configuration of the wiring board according to this embodiment will be described with reference to Figures 1 to 7. Figures 1 to 7 are diagrams showing the wiring board according to this embodiment.

[0022] 1, a wiring board 10 according to this embodiment is disposed on, for example, a display of an image display device. Such wiring board 10 includes a transparent substrate 11 and an antenna pattern area (wiring pattern area) 20 disposed on substrate 11. A power supply section 40 is electrically connected to antenna pattern area 20.

[0023] Of these, substrate 11 has a substantially rectangular shape in a plan view, with its longitudinal direction parallel to the Y direction and its lateral direction parallel to the X direction. Substrate 11 is transparent and substantially flat, with a substantially uniform thickness overall. The length L1 of substrate 11 in the longitudinal direction (Y direction) can be selected, for example, from 100 mm to 200 mm, and the length L2 of substrate 11 in the lateral direction (X direction) can be selected, for example, from 50 mm to 100 mm. Note that substrate 11 may have rounded corners.

[0024] The material of substrate 11 may be any material that is transparent in the visible light range and electrically insulating. In this embodiment, the material of substrate 11 is polyethylene terephthalate, but is not limited thereto. The material of substrate 11 is preferably 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 cycloolefin polymer, or a cellulose resin such as triacetyl cellulose. The material of substrate 11 may also be selected appropriately from glass, ceramics, and the like depending on the application. While the illustrated example shows substrate 11 formed of a single layer, this is not limiting and multiple substrates or layers may be stacked. Substrate 11 may also be in the form of a film or a plate. Therefore, the thickness of substrate 11 is not particularly limited and can be selected appropriately depending on the application. For example, the thickness T1 (length in the Z direction, see FIG. 3 ) of substrate 11 may be in the range of 10 μm to 200 μm.

[0025] 1, there are a plurality (three) of antenna pattern regions 20 on the substrate 11, each corresponding to a different frequency band. That is, the plurality of antenna pattern regions 20 have a length (length in the Y direction) L aThe lengths L of the antenna pattern area 20 are different from each other and correspond to specific frequency bands. a is longer. When wiring board 10 is disposed on, for example, display 91 of image display device 90 (see FIG. 10 described later), if wiring board 10 has a radio wave transmission / reception function, each antenna pattern area 20 may correspond to any of a telephone antenna, a WiFi antenna, a 3G antenna, a 4G antenna, a 5G antenna, an LTE antenna, a Bluetooth (registered trademark) antenna, an NFC antenna, etc. Alternatively, when wiring board 10 does not have a radio wave transmission / reception function, each antenna pattern area 20 may perform functions such as hovering (a function that allows operation without the user directly touching the display), fingerprint authentication, a heater, noise reduction (shielding), etc.

[0026] Each antenna pattern area 20 has a substantially rectangular shape in a plan view. The longitudinal direction of each antenna pattern area 20 is parallel to the Y direction, and the lateral direction (width direction) of each antenna pattern area 20 is parallel to the X direction. The length L of each antenna pattern area 20 in the longitudinal direction (Y direction) is a can be selected, for example, in the range of 3 mm to 100 mm, and the width W a can be selected, for example, in the range of 1 mm to 25 mm.

[0027] In the antenna pattern region 20, metal wires are formed 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, the antenna pattern region 20 is composed of a repetition of L-shaped unit pattern shapes 20a (shaded part in Fig. 2) each consisting of a part extending in the X direction (second-directional wiring 22) and a part extending in the Y direction (first-directional wiring 21).

[0028] As shown in FIG. 2, each antenna pattern area 20 includes a plurality of first directional wirings (wirings) 21 that function as antennas, and a plurality of second directional wirings 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 or mesh shape. Each first directional wiring 21 extends in a direction (Y direction) corresponding to the frequency band of the antenna, and each second directional wiring 22 extends in a direction (X direction) perpendicular to the first directional wiring 21. The first directional wiring 21 has a length L corresponding to a predetermined frequency band. a (See FIG. 1 for the length of the antenna pattern region 20 described above) and thereby functioning mainly as an antenna. On the other hand, the second directional wirings 22 play a role in preventing problems such as disconnection of the first directional wirings 21 and loss of electrical connection between the first directional wirings 21 and the power supply unit 40 by connecting these first directional wirings 21 together.

[0029] In each antenna pattern region 20, a plurality of openings 23 are formed by being surrounded by adjacent first directional wirings 21 and adjacent second directional wirings 22. The first directional wirings 21 and the second directional wirings 22 are arranged at equal intervals. That is, the plurality of first directional wirings 21 are arranged at equal intervals, and the pitch P1 (see FIG. 2) can be, for example, in the range of 0.01 mm to 1 mm. The plurality of second directional wirings 22 are arranged at equal intervals, and the pitch P2 (see FIG. 2) can be, for example, in the range of 0.01 mm to 1 mm. In this way, by arranging the plurality of first directional wirings 21 and the plurality of second directional wirings 22 at equal intervals, the size of the openings 23 within each antenna pattern region 20 is uniform, and the antenna pattern region 20 can be made difficult to see with the naked eye. The pitch P1 of the first directional wirings 21 is equal to the pitch P2 of the second directional wirings 22. Therefore, each opening 23 has a substantially square shape in a plan view, and the transparent substrate 11 is exposed through each opening 23. Therefore, by increasing the area of ​​each opening 23, the transparency of the wiring substrate 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 μm to 1 μm. The first directional wires 21 and the second directional wires 22 are orthogonal to each other, but are not limited to this, and may intersect each other at an acute or obtuse angle. Furthermore, the shape of the openings 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 vary depending on the location.

[0030] As shown in FIG. 3, each first-directional wiring 21 has a cross section perpendicular to its longitudinal direction (X-direction cross section) that is substantially rectangular or square. In this case, the cross-sectional shape of the first-directional wiring 21 is substantially uniform along the longitudinal direction (Y-direction) of the first-directional wiring 21. Also, as shown in FIG. 4, the cross-sectional shape of each second-directional wiring 22 perpendicular to the longitudinal direction (Y-direction cross section) is substantially rectangular or square, and is substantially the same as the cross-sectional shape (X-direction cross section) of the first-directional wiring 21 described above. In this case, the cross-sectional shape of the second-directional wiring 22 is substantially uniform along the longitudinal direction (X-direction) of the second-directional wiring 22. The cross-sectional shapes of the first-directional wiring 21 and the second-directional wiring 22 do not necessarily have to be substantially rectangular or square, and may be, for example, a substantially trapezoidal shape in which the front side (positive side in the Z-direction) is narrower than the back side (negative side in the Z-direction) or a shape in which the side surfaces located on both sides in the width direction are curved.

[0031] In this embodiment, the line width W1 (length in the X direction, see FIG. 3) of the first directional wiring 21 and the line width W2 (length in the Y 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, the line width W1 of the first directional wiring 21 can be selected in the range of 0.1 μm to 5.0 μm, and the line width W2 of the second directional wiring 22 can be selected in the range of 0.1 μm to 5.0 μm. 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, can be selected in the range of 0.1 μm to 5.0 μm.

[0032] 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.

[0033] In this embodiment, the overall aperture ratio At of the antenna pattern region 20 can be set, for example, in the range of 87% or more and less than 100%. By setting the overall aperture ratio At of the antenna pattern region 20 in this range, the conductivity and transparency of the wiring substrate 10 can be ensured. Note that the aperture ratio refers to the ratio (%) of the area of ​​the open region (a region where no metal parts such as the first-directional wiring 21 and the second-directional wiring 22 are present and where the substrate 11 is exposed) to the unit area of ​​a predetermined region (for example, a part of the antenna pattern region 20).

[0034] Referring again to FIG. 1 , the power supply unit 40 is electrically connected to each antenna pattern area 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 power supply unit 40 may be made of a metal material (including an alloy thereof) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel. When the wiring board 10 is incorporated into an image display device 90 (see FIG. 10 ), the power supply unit 40 is electrically connected to a wireless communication circuit 92 of the image display device 90 via a power supply line 95. Note that the power supply unit 40 is provided on the surface of the substrate 11, but this is not limiting, and a part or all of the power supply unit 40 may be located outside the periphery of the substrate 11. In addition, in FIG. 1, a corresponding power supply section 40 is connected to each wiring pattern area 20, but this is not limited to this, and one power supply section 40 may be electrically connected to multiple wiring pattern areas 20.

[0035] As shown in FIG. 5, the plurality of first-directional wirings 21 are electrically connected to a power supply unit 40 on the negative Y-direction side. In this case, the power supply unit 40 is formed integrally with the antenna pattern area 20. A connection area 46 is formed on the opposite side (negative Y-direction side) of the power supply unit 40 from the antenna pattern area 20, and the connection area 46 is electrically connected to a power supply line 95 (described later). The length L4 of the power supply unit 40 in the longitudinal direction (X-direction) may be 1 mm or more and 50 mm or less, and the length L5 of the power supply unit 40 in the lateral direction (Y-direction) may be 0.5 mm or more and 10 mm or less. The thickness T3 (see FIG. 6) of the power supply unit 40 may be the same as the height H1 (see FIG. 3) of the first-directional wirings 21 and the height H2 (see FIG. 4) of the second-directional wirings 22, and may be selected, for example, from the range of 0.1 μm or more and 5.0 μm or less.

[0036] As shown in FIGS. 5 and 6, in this embodiment, power supply unit 40 has an inner region 41 having an uneven surface 41a (see FIG. 6) and an outer region 42 surrounding inner region 41 and having no uneven surface. Inner region 41 has a generally rectangular shape in a plan view. The longitudinal direction of inner region 41 is parallel to the X direction, and the lateral direction (width direction) of inner region 41 is parallel to the Y direction. The length L6 (see FIG. 5) of inner region 41 in the longitudinal direction (X direction) may be 50% to 99% of the length L4 of power supply unit 40 in the longitudinal direction (X direction), and may be 0.5 mm to 49.5 mm. The length L7 (see FIG. 5) of inner region 41 in the lateral direction (Y direction) may be 50% to 99% of the length L5 of power supply unit 40 in the lateral direction (Y direction), and may be 0.25 mm to 9.9 mm. However, the planar shape of the inner region 41 is not limited to this, and may be a circle, an ellipse, a polygon such as a rectangle, or the like.

[0037] The surface roughness Ra of the surface of the inner region 41 may be 0.2 μm or more and 100 μm or less. Here, the surface roughness Ra refers to the arithmetic mean roughness and is measured in accordance with JIS B 0601-2013. When the surface roughness Ra of the surface of the inner region 41 is 0.2 μm or more, the volume of the portion 17a of the protective layer 17 (described later) that penetrates between the convex portions (into the concave portions) of the irregularities 41a of the inner region 41 can be increased. This increases the volume of the portion of the protective layer 17 that acts as an anchor, as described later. This allows for a strong bond between the protective layer 17 and the power supply unit 40. When the surface roughness Ra of the surface of the inner region 41 is 100 μm or less, the thickness of the wiring substrate 10 and the thickness of the image display device 90 (see FIG. 10) in which the wiring substrate 10 is incorporated can be prevented from becoming too thick. In addition, it is possible to prevent partial disconnection of the power supply part 40 provided on the surface of the substrate 11 due to excessively large undulations of the unevenness 41a. Furthermore, by setting the surface roughness Ra of the surface of the inner region 41 to be 0.2 μm or more and 100 μm or less, it is possible to improve the formability of the unevenness 41a of the inner region 41. As an example, the surface roughness Ra can be measured using a laser microscope (Keyence Corporation VK-X250 (controller) and VK-X260 (measuring unit), laser wavelength 408 nm).

[0038] In this case, the irregularities 41a are disposed over substantially the entire surface of the inner region 41, but are not limited thereto. The irregularities 41a are preferably disposed at least in the region covered by the protective layer 17 and in the connection region 46. This can improve adhesion between the protective layer 17 and the power supply unit 40, and between the solder connecting the power supply line 95 and the power supply unit 40. The irregularities 41a in the inner region 41 may be formed, for example, by embossing. Although not shown, for example, forming the irregularities 41a in the inner region 41 may result in multiple through-holes penetrating the power supply unit 40 in the thickness direction (Z direction) being formed in the inner region 41. In this case, the transparent substrate 11 may be exposed through each through-hole.

[0039] The outer region 42 is provided in a frame shape so as to surround the inner region 41. As described above, the outer region 42 does not have any irregularities. Therefore, the surface of the outer region 42 is smooth. In this embodiment, the width W3 (see FIG. 5) of the outer region 42 is substantially uniform around the entire periphery. The width W3 of the outer region may be equal to or greater than a skin depth (described later) of the power supply unit 40, or may be equal to or less than 25% of the length L4 of the power supply unit 40 in the longitudinal direction (X direction). When the width W3 of the outer region 42 is equal to or greater than the skin depth, the area where the irregularities 41a are not formed can be widened. Here, when the irregularities 41a are formed, the length of the path through which the current flows is longer than when the irregularities 41a are not formed. This may result in power loss. On the other hand, when the width W3 of the outer region 42 is equal to or greater than the skin depth, the area where the irregularities 41a are not formed can be widened, thereby reducing power loss in the outer region 42 through which the high-frequency current flows. Furthermore, by making the width W3 of the outer region 42 25% or less of the longitudinal length L4 of the power supply unit 40, when the skin effect described below occurs in the outer region 42, the proportion of the area in the cross section of the outer region 42 through which current flows can be increased. That is, by making the width W3 of the outer region 42 25% or less of the longitudinal length L4 of the power supply unit 40, it becomes possible to allow current to flow across substantially the entire cross section of the outer region 42. This improves the antenna characteristics. Note that the width W3 of the outer region 42 does not have to be substantially uniform around the entire circumference. For example, the width of a portion of the outer region 42 extending along the X direction (length in the Y direction) and the width of a portion of the outer region 42 extending along the Y direction (length in the X direction) may be different from each other.

[0040] The width W3 of the outer region 42 can be determined in consideration of the skin depth of the power feeding section 40. A method for determining the width W3 of the outer region 42 will be described below.

[0041] As described above, the length (length in the Y direction) L of the antenna pattern area 20 a has a length corresponding to a specific frequency band, and the lower the corresponding frequency band, the longer the length La The length L of the antenna pattern area 20 becomes longer. a After determining width W3 of outer region 42, width W3 of outer region 42 may be determined.

[0042] That is, the width W3 of the outer region 42 may be determined in consideration of the skin effect depending on the corresponding frequency band. Specifically, as will be described later, the width W3 of the outer region 42 may be set to be equal to or greater than the skin depth of the power supply section 40.

[0043] Generally, when an alternating current is passed through a conductor, the higher the frequency, the more difficult it becomes for the current to flow through the center of the conductor, and the more the current flows on the surface of the conductor. This phenomenon in which current flows only on the surface when an alternating current is passed through a conductor is called the skin effect. Additionally, skin depth refers to the depth from the surface of the conductor where the current attenuates to 1 / e (approximately 0.37) times the current on the surface of the conductor, where the current flows most easily. This skin depth δ can generally be calculated using the following formula.

[0044]

number

[0045] In the above formula, ω is the angular frequency (=2πf), μ is the magnetic permeability (4π×10 in a vacuum) -7 [H / m]), σ is the conductivity of the conductor (5.8×10 for copper) 7 The skin depth δ of copper wiring is approximately 2.3 μm when the frequency is 0.8 GHz, approximately 1.3 μm when the frequency is 2.4 GHz, approximately 1.0 μm when the frequency is 4.4 GHz, and approximately 0.85 μm when the frequency is 6 GHz.

[0046] In this embodiment, for example, as shown in FIG. 7, the width W3 of the outer region 42 may be equal to or greater than the skin depth δ of the frequency of the corresponding antenna pattern region 20 (δ≦W3). In this case, for example, when the frequency of the antenna pattern region 20 is 2.4 GHz, W3 may be equal to or greater than 1.3 μm, and when the frequency of the antenna pattern region 20 is 6 GHz, W3 may be equal to or greater than 0.85 μm. Since the width W3 of the outer region 42 is equal to or greater than the skin depth δ, the current flows through the outer region 42, where the irregularities 41 a are not formed, rather than through the inner region 41, where the irregularities 41 a are formed. In other words, the current flows through the outer region 42, which has a smooth surface, preventing the length of the current path from becoming too long. This reduces power loss. In this case, it is preferable that a corresponding power supply unit 40 is connected to each antenna pattern region 20, as shown in FIG. 1. On the other hand, when one power supply section 40 is electrically connected to multiple antenna pattern areas 20, the skin depth δ of the power supply section 40 may be calculated based on the frequency of the antenna pattern area 20 with the lowest frequency.

[0047] 3, 4, and 6, a protective layer 17 is formed on the surface of the substrate 11 to cover the antenna pattern region 20 and the power supply portion 40. The protective layer 17 protects the antenna pattern region 20 and the power supply portion 40 and may be formed over substantially the entire surface of the substrate 11. Examples of materials that can be used for the protective layer 17 include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate, modified resins thereof, copolymers thereof, polyester, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, copolymers thereof, polyurethane, epoxy resin, polyamide, and chlorinated polyolefin, and other colorless and transparent insulating resins. The thickness T2 (see FIG. 3) of the protective layer 17 can be selected from the range of 0.3 μm to 100 μm.

[0048] 6, the region of the protective layer 17 corresponding to the inner region 41 of the power supply unit 40 has a shape that is a transfer of the irregularities 41a of the inner region 41. As a result, the portion 17a of the protective layer 17 penetrates between the convex portions (into the concave portions) of the irregularities 41a of the inner region 41 and hardens, so that the portion 17a of the protective layer 17 serves as an anchor. This allows the protective layer 17 to adhere strongly to the power supply unit 40, preventing the protective layer 17 from peeling off from the power supply unit 40. Note that the protective layer 17 may not cover the connection region 46 of the power supply unit 40 to make it easier to connect the power supply line 95 to the power supply unit 40.

[0049] [Method of manufacturing wiring board] Next, a method for manufacturing a wiring board according to this embodiment will be described with reference to Figures 8(a)-(f) and 9(a)-(d). Figures 8(a)-(f) and 9(a)-(d) are cross-sectional views showing the method for manufacturing a wiring board according to this embodiment.

[0050] First, as shown in FIG. 8(a), a transparent substrate 11 is prepared.

[0051] Next, an antenna pattern region 20 including a plurality of first directional wirings 21 and a power supply section 40 electrically connected to the antenna pattern region 20 are formed on the substrate 11. At this time, a conductive layer 51 is first formed over substantially the entire surface of the substrate 11. In this embodiment, the thickness of the conductive layer 51 is 200 nm. However, this is not limited thereto, and the thickness of the conductive layer 51 can be appropriately selected within a range of 10 nm to 1000 nm. In this embodiment, the conductive layer 51 is formed by a sputtering method using copper. The conductive layer 51 may also be formed by a plasma CVD method.

[0052] 8(b), a photo-curable insulating resist 52 is applied to almost the entire surface of the substrate 11. Examples of the photo-curable insulating resist 52 include organic resins such as acrylic resins and epoxy resins.

[0053] 8(c), an insulating layer 54 is formed by photolithography. In this case, the photo-curable insulating resist 52 is patterned by photolithography to form an insulating layer 54 (resist pattern) in which trenches 54a are formed. The trenches 54a have a planar shape pattern corresponding to the first-directional wiring 21 and the second-directional wiring 22. At this time, the insulating layer 54 is formed so that the conductive layer 51 corresponding to the first-directional wiring 21 and the second-directional wiring 22 is exposed.

[0054] Alternatively, the trenches 54a can be formed in the surface of the insulating layer 54 by an imprinting method. In this case, a transparent imprinting mold having protrusions corresponding to the trenches 54a is prepared, the mold is brought close to the substrate 11, and a photocurable insulating resist 52 is spread between the mold and the substrate 11. Next, light is irradiated from the mold side to harden the photocurable insulating resist 52, thereby forming the insulating layer 54. As a result, trenches 54a having the shape of the transferred protrusions are formed in the surface of the insulating layer 54. The mold is then peeled off from the insulating layer 54, thereby obtaining the insulating layer 54 with the cross-sectional structure shown in FIG. 8(c). Although not shown, residual insulating material may remain at the bottom of the trenches 54a in the insulating layer 54. Therefore, the residual insulating material is removed by wet treatment using a permanganate solution or N-methyl-2-pyrrolidone, or dry treatment using oxygen plasma. By removing the residual insulating material in this manner, trenches 54a exposing the conductive layer 51 can be formed, as shown in FIG. 8(c).

[0055] 8(d), the trenches 54a in the insulating layer 54 are filled with a conductor 55. In this embodiment, the trenches 54a in the insulating layer 54 are filled with copper by electroplating using the conductive layer 51 as a seed layer.

[0056] 8(e), the insulating layer 54 is removed by wet treatment using a permanganate solution, N-methyl-2-pyrrolidone, an acid or alkaline solution, or dry treatment using oxygen plasma.

[0057] Thereafter, as shown in FIG. 8( f), the conductive layer 51 on the surface of the substrate 11 is removed. At this time, a wet process using hydrogen peroxide is performed to etch the conductive layer 51 so that the surface of the substrate 11 is exposed. In this manner, a wiring board 10 (hereinafter also simply referred to as wiring board 10a) is obtained, which includes the substrate 11, the antenna pattern region 20 arranged on the substrate 11, and the power supply unit 40 before the unevenness 41a is formed in the inner region 41. In this case, the antenna pattern region 20 includes first-directional wiring 21 and second-directional wiring 22. The above-mentioned conductor 55 includes the first-directional wiring 21 and the second-directional wiring 22. At this time, the power supply unit 40 before the unevenness 41a is formed in the inner region 41 may be formed by a part of the conductor 55. Alternatively, a flat-plate-shaped power supply unit 40 before the unevenness 41a is formed in the inner region 41 may be separately prepared, and this power supply unit 40 may be electrically connected to the wiring pattern region 20.

[0058] Next, the unevenness 41a is formed in the inner region 41. The unevenness 41a in the inner region 41 may be formed by, for example, embossing. In this case, first, as shown in Fig. 9(a), a first mold 61 having a flat surface 61a is prepared.

[0059] Next, as shown in FIG. 9(b), the wiring board 10a is placed on the flat surface 61a of the first mold 61.

[0060] Also, a second mold 62 (see FIG. 9(c)) is prepared. In this second mold 62, concaves and convexes 62a corresponding to the concaves and convexes 41a of the inner region 41 are formed.

[0061] 9(c), wiring board 10a is sandwiched between first die 61 and second die 62 so that concave-convex shape 62a of second die 62 faces power supply unit 40 of wiring board 10a. As a result, the concave-convex shape of concave-convex shape 62a of second die 62 is transferred to inner region 41 of power supply unit 40, forming concave-convex shape 41a in inner region 41. Note that concave-convex shape 62a may be heated in advance to facilitate deformation of substrate 11 and power supply unit 40 of wiring board 10a.

[0062] Thereafter, the wiring substrate 10a is removed from the first mold 61 and the second mold 62, and as shown in FIG. 9(d), a protective layer 17 is formed to cover the antenna pattern region 20 and the power supply unit 40 on the substrate 11. The protective layer 17 may be formed by roll coating, gravure coating, gravure reverse coating, microgravure coating, slot die coating, die coating, knife coating, inkjet coating, dispenser coating, kiss coating, spray coating, screen printing, offset printing, or flexographic printing. At this time, portions 17a of the protective layer 17 penetrate into the spaces between the convex portions (into the concave portions) of the irregularities 41a and harden, thereby firmly bonding the protective layer 17 to the power supply unit 40 (see FIG. 6).

[0063] In this way, a wiring board 10 is obtained that includes the substrate 11, the antenna pattern area 20 arranged on the substrate 11, and the power supply section 40 electrically connected to the antenna pattern area 20.

[0064] [Operation of this embodiment] Next, the operation of the wiring board having such a configuration will be described.

[0065] As shown in FIG. 10 , 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 image display devices 90 include mobile terminal devices such as smartphones and tablets. The antenna pattern region 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 and a power supply line 95. In this way, radio waves of a predetermined frequency can be transmitted and received via the antenna pattern region 20, and communication can be performed using the image display device 90.

[0066] Generally, power supply unit 40 contacts protective layer 17 over a larger area than first-directional wiring 21 and second-directional wiring 22. However, because metal power supply unit 40 and resin protective layer 17 are made of different materials, their adhesion is not necessarily strong. For this reason, if a force is applied to wiring substrate 10 in a bending direction while image display device 90 is in use, protective layer 17 may peel off from power supply unit 40, and this may serve as a starting point for protective layer 17 to peel off from the entire surface of substrate 11.

[0067] In contrast, according to the present embodiment, power supply unit 40 has inner region 41 in which irregularities 41a are formed, and outer region 42 in which no irregularities are formed and which is provided around inner region 41. As a result, parts 17a of protective layer 17 that have penetrated between the convex portions (into the concave portions) of irregularities 41a in inner region 41 serve as anchors, firmly bonding protective layer 17 and power supply unit 40. This makes it possible to prevent protective layer 17 from peeling off from power supply unit 40. Furthermore, because outer region 42 in which irregularities are not formed is provided around inner region 41, it is possible to prevent the length of the path through which current flows from becoming longer, thereby reducing power loss.

[0068] In order to more firmly bond the protective layer 17 and the power supply unit 40, it may be necessary to increase the volume of the portion of the protective layer 17 that acts as an anchor. To allow a portion of the protective layer to act as an anchor, a through-hole may be formed in the power supply unit 40 that penetrates the power supply unit 40 in the thickness direction (Z direction), and a portion of the protective layer 17 may enter the through-hole to act as an anchor. On the other hand, if the power supply unit 40 is thin, it may be difficult to increase the volume of the portion of the protective layer 17 that enters the through-hole. In this case, it becomes difficult to increase the volume of the portion of the protective layer 17 that acts as an anchor. In contrast, in the present embodiment, the inner region 41 is formed with irregularities 41a. By changing the size of the irregularities 41a, the volume of the portion 17a of the protective layer 17 that enters between the protrusions (into the recesses) can be easily increased. Therefore, by forming the irregularities 41a in the inner region 41, the protective layer 17 and the power supply portion 40 can be bonded more firmly than when the above-mentioned through holes are formed in the power supply portion 40.

[0069] Furthermore, according to this embodiment, solder for connecting the power feed line 95 to the power supply unit 40 can be introduced between the convex portions (into the concave portions) of the irregularities 41a of the inner region 41. As a result, part of the solder that has introduced between the convex portions (into the concave portions) of the irregularities 41a serves as an anchor and is coupled to the power supply unit 40. This allows the power feed line 95 to be firmly connected to the power supply unit 40.

[0070] Furthermore, according to the present embodiment, the wiring board 10 includes the transparent substrate 11 and the antenna pattern region 20 that is disposed on the substrate 11 and includes a plurality of first directional wires 21, thereby ensuring the transparency of the wiring board 10. As a result, when the wiring board 10 is disposed on the display 91, the display 91 can be viewed through the openings 23 of the antenna pattern region 20, and the visibility of the display 91 is not obstructed.

[0071] Furthermore, according to this embodiment, a protective layer 17 is formed so as to cover the antenna pattern area 20 and the power supply part 40. This makes it possible to protect the antenna pattern area 20 and the power supply part 40 from external impacts and the like.

[0072] (Variation) Next, various modified examples of the wiring board according to this embodiment will be described with reference to Figures 11 and 12. Figures 11 and 12 are diagrams showing various modified examples of the wiring board. The modified examples shown in Figures 11 and 12 differ in the configuration of the power supply section 40 or the wiring pattern region 20, but other configurations are substantially the same as those of the embodiment shown in Figures 1 to 10 described above. In Figures 11 and 12, the same parts as those shown in Figures 1 to 10 are given the same reference numerals, and detailed description thereof will be omitted.

[0073] (Variation 1) Fig. 11 shows wiring board 10A according to Modification 1 of the present embodiment. In Fig. 11, unevenness 42a that is smaller than unevenness 41a of inner region 41 is formed in outer region 42. In other words, unevenness 42a is formed in outer region 42, and the surface roughness Ra of the surface of outer region 42 is smaller than the surface roughness Ra of the surface of inner region 41.

[0074] 11 , a region of protective layer 17 corresponding to outer region 42 of power supply unit 40 may have a shape that is a transfer of asperities 42a of outer region 42. As a result, portions 17b of protective layer 17 penetrate into the spaces between the protruding portions (into the recessed portions) of asperities 42a of outer region 42 and harden, so that portions 17b of protective layer 17 serve as anchors. This allows protective layer 17 to adhere strongly to power supply unit 40, preventing protective layer 17 from peeling off from power supply unit 40.

[0075] In this modification, the surface roughness Ra of at least a portion of the outer region 42 may be 10 nm or more and 100 nm or less. When the surface roughness Ra of the surface of the outer region 42 is 10 nm or more, the portion 17b of the protective layer 17 that penetrates between the convex portions (into the concave portions) of the asperities 42a of the outer region 42 can act as an anchor. Furthermore, when the surface roughness Ra of the surface of the outer region 42 is 100 nm or less, it is possible to prevent the length of the current path from becoming too long due to the asperities 42a. This reduces power loss.

[0076] (Variation 2) FIG. 12 shows a wiring board 10B according to a second modification of the present embodiment. In FIG. 12, the first-directional wirings 21 and the second-directional wirings 22 intersect at an angle, and each opening 23 is formed in a diamond shape in a plan view. The first-directional wirings 21 and the second-directional wirings 22 are non-parallel to both the X and Y directions. Within the wiring pattern region 20, a region 28 adjacent to the power supply unit 40 and surrounded by the power supply unit 40, the first-directional wirings 21, and the second-directional wirings 22 is a non-opening. This region 28 is triangular in a plan view. That is, the region 28 is filled with metals constituting the first-directional wirings 21, the second-directional wirings 22, and the power supply unit 40, and the substrate 11 is not exposed. This increases the strength of the first-directional wirings 21 and the second-directional wirings 22 near the power supply unit 40, where current density is likely to be high and breakage is likely to occur after long-term use, thereby preventing breakage of the first-directional wirings 21 and the second-directional wirings 22.

[0077] All of the multiple regions 28 surrounded by the power supply section 40, the first directional wiring 21, and the second directional wiring 22 may be non-openings, or only some of the multiple regions 28 may be non-openings. In the latter case, for example, the multiple regions 28 located near the center of the wiring pattern region 20 in the width direction (X direction) may be openings, and the multiple regions 28 located near the edges of the wiring pattern region 20 in the width direction (X direction) may be non-openings.

[0078] It is also possible to combine the multiple components disclosed in the above-described embodiments and modifications as needed, or to delete some of the components disclosed in the above-described embodiments and modifications. [Explanation of symbols]

[0079] 10. Wiring board 11 Circuit Board 17 Protective layer 20 Antenna pattern area 21 1st direction wiring 40 Power supply unit 41 Inner area 41a Unevenness 42 Outer area 42a Unevenness

Claims

1. A wiring board, A substrate; a wiring pattern area disposed on the substrate and including a plurality of wirings; a power supply section electrically connected to the wiring pattern area, The power supply unit is An inner region; an outer region provided around the inner region, the surface roughness Ra of the surface of the outer region is smaller than the surface roughness Ra of the surface of the inner region; Concaves and convexes are formed in the inner region, and convexo-concaves smaller than the convexo-convexities in the inner region are formed in the outer region, The surface of the outer region has a surface roughness Ra of 10 nm or more and 100 nm or less.

2. 2. The wiring board according to claim 1, wherein the surface roughness Ra of the surface of the inner region is 0.2 [mu]m or more and 100 [mu]m or less.

3. 3. The wiring board according to claim 1, wherein the width of the outer region is equal to or greater than the skin depth of the power supply portion.

4. The wiring board according to claim 3 , wherein the width of the outer region is 25% or less of the length of the power supply portion in the longitudinal direction.

5. The wiring board according to claim 1 , further comprising a protective layer formed on the board so as to cover the wiring pattern area and the power supply portion.

6. The wiring board according to claim 5 , wherein a region of the protective layer corresponding to the inner region of the power supply portion has a shape that is a transfer of the irregularities of the inner region.

7. 7. The wiring board according to claim 5, wherein an area of ​​said protective layer corresponding to said outer area of ​​said power supply portion has a shape formed by transferring unevenness of said outer area.

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

9. A method for manufacturing a wiring substrate, providing a substrate; forming a wiring pattern area including a plurality of wirings on the substrate, and a power supply portion electrically connected to the wiring pattern area; The power supply unit is An inner region; an outer region provided around the inner region, the surface roughness Ra of the surface of the outer region is smaller than the surface roughness Ra of the surface of the inner region; Concaves and convexes are formed in the inner region, and convexo-concaves smaller than the convexo-convexities in the inner region are formed in the outer region, The method for manufacturing a wiring substrate, wherein the surface roughness Ra of the surface of the outer region is 10 nm or more and 100 nm or less.

10. The method for manufacturing a wiring board according to claim 9 , wherein the inner region is formed with unevenness, and the unevenness of the inner region is formed by embossing.

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