Conductive film

Abstract

This conductive film (1) is provided with a base material (10), a resin layer (20) disposed above the base material (10), a covering member (30) disposed above the resin layer (20), and an adhesive layer (40) which bonds the resin layer (20) and the covering member (30) to each other, wherein: the resin layer (20) has a first portion (21) and a second portion (22) that is thicker than the first portion (21); the first portion (21) is provided with a first metal wire (51) that is a first conductor; the second portion (22) is provided with a second metal wire (52) that is a second conductor; the area occupancy of the first metal wire (51) is smaller than the area occupancy of the second metal wire (52) in a plan view of the conductive film (1); and the thickness of the adhesive layer (40) positioned between the second portion (22) and the covering member (30) is less than the thickness of the adhesive layer (40) positioned between the first portion (21) and the covering member (30).

Description

Conductive film

[0001] The present disclosure relates to conductive films.

[0002] Electrical devices use wiring boards having metal wires formed on a substrate. The wiring boards are used as touch sensor substrates provided with sensor electrodes, or as mounting substrates on which electronic components such as circuit elements are mounted. For example, a touch panel is known as an electrical device using a wiring board as a touch sensor substrate, in which fine metal wires serving as sensor electrodes are formed in a mesh pattern on a transparent film substrate (see, for example, Patent Document 1).

[0003] The fine metal lines formed on the touch sensor substrate have a line width of 100 μm or less, making them difficult to see with the naked eye. Therefore, the touch sensor substrate used in the touch panel appears to be a transparent film, even though the sensor electrodes are formed of light-shielding metal lines. In other words, the touch sensor substrate used in the touch panel is a transparent conductive film on which conductive metal lines are formed and which appears transparent.

[0004] This type of transparent conductive film includes, for example, a transparent substrate, a transparent resin layer laminated on the transparent substrate, metal wires embedded in grooves in the resin layer, a transparent covering member such as a cover glass placed above the resin layer, and a transparent adhesive layer that bonds the resin layer and the covering member.

[0005] Japanese Patent Application Laid-Open No. 2003-114762

[0006] A transparent conductive film used in a touch panel has an effective area (a view area seen by the user) which is the area touched by the user using the touch panel, and an ineffective area (an area not visible to the user) located outside the effective area.

[0007] In a transparent conductive film used in a touch panel, the effective area is a mesh area in which metal wires that serve as sensor electrodes are formed in a mesh pattern, and the ineffective area is a wiring area in which metal wires (wiring) are routed to electrically connect the metal wires in the mesh area to a circuit board.

[0008] The metal lines formed in the mesh region have a line width of 100 μm or less, which is thinner than the metal lines formed in the wiring region, and therefore the area occupancy rate of the metal lines in the wiring region is higher than the area occupancy rate of the metal lines in the mesh region.

[0009] A transparent conductive film configured in this manner has a problem in that the adhesive layer may expand or contract thermally, causing peeling of the covering member, particularly in wiring regions where the area occupancy of metal wires is high.

[0010] The present disclosure has been made to solve such problems, and aims to provide a conductive film or the like that can prevent peeling of a covering member.

[0011] In order to achieve the above-mentioned object, one aspect of the conductive film according to the present disclosure comprises a substrate, a resin layer disposed above the substrate, a covering member disposed above the resin layer, and an adhesive layer disposed between the resin layer and the covering member and adhering the resin layer and the covering member, wherein the resin layer has a first portion and a second portion thicker than the first portion, a first conductor is provided in the first portion, a second conductor is provided in the second portion, the first conductor and the second conductor are in contact with the adhesive layer, and in a planar view of the conductive film, the area occupancy rate of the first conductor in the first portion is smaller than the area occupancy rate of the second conductor in the second portion, and the thickness of the adhesive layer located between the second portion and the covering member is thinner than the thickness of the adhesive layer located between the first portion and the covering member.

[0012] According to the present disclosure, peeling of the covering member can be suppressed.

[0013] FIG. 1 is a perspective view schematically illustrating a conductive film according to an embodiment. FIG. 2 is a partial cross-sectional view of the conductive film according to the embodiment when cut along line II-II in FIG. 1. FIG. 3A is a diagram illustrating a step of preparing a substrate in a method for manufacturing a conductive film according to an embodiment. FIG. 3B is a diagram illustrating a step of forming a resin layer having grooves on a substrate in a method for manufacturing a conductive film according to an embodiment. FIG. 3C is a diagram illustrating a step of forming metal wires in the grooves in the resin layer in a method for manufacturing a conductive film according to an embodiment. FIG. 3D is a diagram illustrating a step of bonding a covering member to a resin layer in a method for manufacturing a conductive film according to an embodiment. FIG. 4 is a diagram illustrating an example of the step of FIG. 3D. FIG. 5A is a diagram illustrating a state after the step of FIG. 3B, which precedes the step of FIG. 3C, is completed. FIG. 5B is a diagram illustrating a step of forming a first metal film on a resin layer in the step of FIG. 3C. FIG. 5C is a diagram illustrating a step of forming a second metal film on a resin layer in the step of FIG. 3C. FIG. 5D is a diagram illustrating a step of forming a metal layer on a resin layer in the step of FIG. 3C. Fig. 5E is a diagram showing a step of removing excess metal layer and the like formed outside the grooves in the step of Fig. 3C. Fig. 5F is a diagram showing a step of blackening the surface layer of the metal layer in the step of Fig. 3C. Fig. 6 is a partial cross-sectional view of a conductive film of a comparative example. Fig. 7 is a plan view of a conductive film according to Modification 1. Fig. 8 is a partial cross-sectional view of a conductive film according to Modification 1 when cut along line VIII-VIII in Fig. 7. Fig. 9 is a partial cross-sectional view of a conductive film according to Modification 2.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, the arrangement and connection of the components, processes (steps), and the order of the processes shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0015] Note that each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. Furthermore, in each figure, substantially the same configuration is assigned the same reference numeral, and duplicate explanations are omitted or simplified. Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition.

[0016] (Embodiment) First, the configuration of a conductive film 1 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view schematically showing the conductive film 1 according to the embodiment. Figure 2 is a partial cross-sectional view of the conductive film 1 according to the embodiment. Figure 2 shows a cross section taken along line II-II in Figure 1.

[0017] The conductive film 1 shown in Fig. 1 is a wiring board on which metal wires of a predetermined shape are formed. In this embodiment, the conductive film 1 is a film-like wiring board having flexibility. The conductive film 1 is also a wiring board having light-transmitting properties. In this embodiment, the conductive film 1 is a film-like transparent wiring board. In other words, the conductive film 1 is a transparent conductive film that is transparent enough to allow the other side to be seen through.

[0018] 1, a flexible wiring board 2 is connected to a conductive film 1. The flexible wiring board 2 may be a wiring board having only metal wires and having a wiring function, or may be a COF (chip on film) on which a semiconductor chip such as a driver IC is mounted.

[0019] As shown in FIG. 1 , the conductive film 1 has an effective area 1a (active area) and an ineffective area 1b (inactive area) located outside the effective area 1a. As an example, the effective area 1a is a rectangular area. The ineffective area 1b is a frame-shaped area (frame area) surrounding the effective area 1a. The ineffective area 1b is a peripheral area located on the periphery of the conductive film 1. A flexible wiring board 2 is connected to the ineffective area 1b. For example, the conductive film 1 and the flexible wiring board 2 are joined in the ineffective area 1b by a conductive bonding member such as an anisotropic conductive film (ACF) or solder.

[0020] In this embodiment, the effective area 1a is a mesh area in which the first metal wires 51 are formed in a mesh pattern. The ineffective area 1b is a wiring area in which the second metal wires 52 (wiring) are routed to electrically connect the first metal wires 51 in the effective area 1a, which is a mesh area, to the flexible wiring board 2. A plurality of the second metal wires 52 are formed in the ineffective area 1b.

[0021] The conductive film 1 is used as a touch sensor substrate in a touch panel. In this case, the effective area 1a is the area touched by a user of the touch panel (the view area seen by the user), and the first metal wires 51 formed in a mesh pattern in the effective area 1a serve as sensor electrodes. On the other hand, the ineffective area 1b, where the second metal wires 52 are formed, is an area that is not visible to the user.

[0022] As shown in FIG. 2 , the conductive film 1 includes a substrate 10, a resin layer 20 disposed above the substrate 10, a covering member 30 disposed above the resin layer 20, and an adhesive layer 40 that bonds the resin layer 20 and the covering member 30 together.

[0023] The substrate 10 is a substrate that serves as a base film for the conductive film 1. Specifically, the substrate 10 is a flexible sheet-like film substrate.

[0024] In this embodiment, the substrate 10 is a light-transmitting substrate that is transmissive to visible light. Specifically, the substrate 10 is a transparent substrate that has such high transmittance that the other side can be seen through it.

[0025] The substrate 10 is made of a resin material. In this embodiment, the substrate 10 is made of a translucent resin material. Specifically, the substrate 10 is made of a transparent resin material. The substrate 10 is an insulating substrate. Therefore, the substrate 10 is made of a transparent insulating resin material. The substrate 10 is a flat, planar plate with a constant thickness, and has a first surface and a second surface opposite to the first surface. The shape of the substrate 10 when viewed from above is, for example, rectangular, but is not limited to this.

[0026] Examples of the translucent resin material that can be used to form the substrate 10 include polyethylene terephthalate (PET) resin, polyimide (PI) resin, polyethylene naphthalate (PEN) resin, cycloolefin resin, polycarbonate resin, and acrylic resin. In this embodiment, the substrate 10 is a transparent PET film made of PET. Alternatively, a transparent glass substrate may be used as the substrate 10.

[0027] The resin layer 20 is located above the substrate 10. In the present embodiment, the resin layer 20 is laminated on one surface of the substrate 10. Specifically, the resin layer 20 is formed directly on the substrate 10. Therefore, the upper surface of the substrate 10 is in contact with the lower surface of the resin layer 20.

[0028] The resin layer 20 is an insulating layer made of an insulating resin material. In this embodiment, the resin layer 20 is made of an insulating resin material having light-transmitting properties. Specifically, the resin layer 20 is made of a transparent insulating resin material. The resin material that makes up the resin layer 20 is a thermosetting resin or an ultraviolet-curing resin. Specifically, the resin material that makes up the resin layer 20 can be, for example, a PET resin, a polyimide resin, a cycloolefin resin, a polycarbonate resin, or an acrylic resin.

[0029] Metal wires 50 are formed in the resin layer 20. Specifically, first metal wires 51 and second metal wires 52 having different line widths are formed as the metal wires 50 in the resin layer 20. In the present embodiment, the line width of the first metal wire 51 is smaller than the line width of the second metal wire 52.

[0030] The first metal wire 51 is a fine metal wire having a line width on the order of micrometers. As an example, the line width of the first metal wire 51 is 100 μm or less, and in this embodiment, it is 10 μm or less. On the other hand, the line width of the second metal wire 52 is 5 μm to 200 μm, and in this embodiment, it is 20 μm.

[0031] As shown in FIG. 1 , a plurality of first metal lines 51 are formed in the effective region 1 a. A plurality of second metal lines 52 are also formed in the ineffective region 1 b. The line width of each of the plurality of first metal lines 51 is constant. Similarly, the line width of each of the plurality of second metal lines 52 is also constant. Note that the plurality of first metal lines 51 may include first metal lines 51 with different line widths. Furthermore, the plurality of second metal lines 52 may include second metal lines 52 with different line widths.

[0032] The first metal wire 51 and the second metal wire 52 are made of the same metal material. For example, the first metal wire 51 and the second metal wire 52 are copper wirings mainly made of copper. The first metal wire 51 and the second metal wire 52 may be made of a laminated film in which multiple metal layers are stacked. Furthermore, the first metal wire 51 and the second metal wire 52 are formed in the same process. In other words, the first metal wire 51 and the second metal wire 52 are formed simultaneously. Note that the first metal wire 51 and the second metal wire 52 may be made of different metal materials or may be formed in different processes.

[0033] The resin layer 20 has a first portion 21 and a second portion 22 that is thicker than the first portion 21. That is, the first portion 21 is a first resin portion that is a thin portion, and the second portion 22 is a second resin portion that is a thick portion. The second portion 22 is a convex portion formed in a convex shape with respect to the first portion 21. On the other hand, the first portion 21 is a concave portion formed in a concave shape with respect to the second portion 22. Therefore, the upper surface of the resin layer 20 (the surface on the adhesive layer 40 side) has an uneven structure formed by the first portion 21 and the second portion 22. The lower surface of the resin layer 20 (the surface on the substrate 10 side) is a flat, planar surface.

[0034] The second portion 22 of the resin layer 20 is provided along the outer periphery of the substrate 10. Specifically, the second portion 22 is provided in the ineffective region 1b. Therefore, in a plan view of the conductive film 1, the second portion 22 is provided in a frame shape. Furthermore, the first portion 21 of the resin layer 20 is formed in the effective region 1a. Therefore, in a plan view of the conductive film 1, the first portion 21 is provided in a rectangular shape.

[0035] 2 , a first metal wire 51 is formed as a first conductor in the first portion 21 of the resin layer 20. That is, the first metal wire 51 has a narrow line width and is formed in the first portion 21. Specifically, the first metal wire 51 is embedded in a groove 20a provided in the first portion 21. The first metal wire 51 is exposed from the resin layer 20, and the upper surface of the first metal wire 51 is in contact with the adhesive layer 40. In this embodiment, the upper surface (exposed surface) of the first metal wire 51 embedded in the groove 20a is flush with the upper surface of the resin layer 20.

[0036] The first metal wires 51 are formed in a mesh shape over the entire first portion 21. In this embodiment, the first metal wires 51 are formed over the entire effective area 1a, which is a mesh region. As shown in FIG. 1 , the mesh-shaped first metal wires 51 include a plurality of first directional lines 51a extending in a first direction and a plurality of second directional lines 51b extending in a second direction intersecting the first direction. In this embodiment, the first directional lines 51a and the second directional lines 51b are not orthogonal to each other, but they may be orthogonal to each other. Furthermore, the plurality of first directional lines 51a are parallel to each other. Similarly, the plurality of second directional lines 51b are parallel to each other. The plurality of first directional lines 51a and the plurality of second directional lines 51b are formed on the same plane. Therefore, the plurality of first directional lines 51a and the plurality of second directional lines 51b are integrated at the intersections where the first directional lines 51a and the second directional lines 51b intersect.

[0037] A second metal wire 52 is formed as a second conductor in the second portion 22 of the resin layer 20. That is, the second metal wire 52 has a wide line width and is formed in the second portion 22. Specifically, the second metal wire 52 is embedded in a groove 20a provided in the second portion 22. The second metal wire 52 is exposed from the resin layer 20, and the upper surface of the second metal wire 52 is in contact with the adhesive layer 40. In this embodiment, the upper surface (exposed surface) of the second metal wire 52 embedded in the groove 20a and the upper surface of the resin layer 20 are flush with each other.

[0038] The second metal wire 52 is formed in a predetermined region of the second portion 22. That is, the second metal wire 52 is formed in a predetermined region of the ineffective region 1b, which is a wiring region. Specifically, the second metal wire 52 is formed in a straight line along the outer periphery of the substrate 10.

[0039] The grooves 20a formed in the resin layer 20 are linear recesses formed so as to indent the surface of the resin layer 20. Specifically, the grooves 20a are formed in a straight or curved shape. The grooves 20a formed in the first portion 21 of the resin layer 20 are formed in a shape corresponding to the first metal wires 51. The grooves 20a formed in the second portion 22 of the resin layer 20 are formed in a shape corresponding to the second metal wires 52. The grooves 20a have a bottom surface and side surfaces that are continuously connected to the bottom surface. In this embodiment, the cross-sectional shape of the grooves 20a when cut along a cross section perpendicular to the longitudinal direction of the grooves 20a is rectangular. In this cross section, the grooves 20a have a planar bottom surface and a pair of planar, opposing side surfaces.

[0040] In this embodiment, the resin layer 20 having the grooves 20a formed therein is formed by an imprinting method. That is, the resin layer 20 is an imprinted layer. In this case, the resin layer 20 having the grooves 20a can be formed by pressing a die member (mold) having protrusions corresponding to the grooves 20a against the resin layer 20. Note that the resin layer 20 having the grooves 20a can also be formed by a method other than the imprinting method. Specifically, the resin layer 20 having the grooves 20a can be formed by forming a flat resin layer 20 and then forming the grooves 20a in the resin layer 20. For example, the grooves 20a can be formed by cutting out the surface of the flat resin layer 20 using laser scribing or the like.

[0041] In a plan view of the conductive film 1, the area occupancy of the first metal wires 51 (first conductors) in the first portion 21 corresponding to the mesh region is smaller than the area occupancy of the second metal wires 52 (second conductors) in the second portion 22 corresponding to the wiring region (i.e., the wiring density is low). In other words, the proportion of metal wires 50 per unit area in the mesh region (first portion 21) is smaller than the proportion of metal wires 50 per unit area in the wiring region (second portion 22). Conversely, the area occupancy of the second metal wires 52 (second conductors) in the second portion 22 corresponding to the wiring region is larger than the area occupancy of the first metal wires 51 (first conductors) in the first portion 21 corresponding to the mesh region (i.e., the wiring density is high).

[0042] The coating member 30 is a cover member that covers the resin layer 20 on which the metal wires 50 are formed. The coating member 30 is laminated on the resin layer 20 via an adhesive layer 40. In other words, the coating member 30 is bonded by the adhesive layer 40 to the base material 10 on which the resin layer 20 on which the metal wires 50 are formed is laminated.

[0043] In this embodiment, the covering member 30 is a flexible sheet-like film substrate. The covering member 30 is a translucent substrate that is translucent to visible light. Specifically, the covering member 30 is a transparent substrate with a high transmittance that allows the viewer to see through it. In this case, the covering member 30 can be a transparent resin cover made of a transparent resin material such as PET resin or a cover glass made of a glass material. The covering member 30 is an insulating substrate made of an insulating material. The covering member 30 is a flat, planar plate with a constant thickness and has a first surface and a second surface opposite the first surface. The top view shape of the covering member 30 is, for example, rectangular, but is not limited thereto.

[0044] The adhesive layer 40 that bonds the resin layer 20 and the covering member 30 is located between the resin layer 20 and the covering member 30. Specifically, the adhesive layer 40 fills the entire gap between the resin layer 20 and the covering member 30. Therefore, the first portion 21 and the second portion 22, which have different thicknesses, form an uneven structure on the surface of the resin layer 20, but the resin layer 20 fills the gap between the resin layer 20 and the covering member 30 so as to flatten the uneven structure of the resin layer 20. Therefore, the thickness of the adhesive layer 40 is different between the first portion 21 and the second portion 22, which have different thicknesses. Specifically, the thickness of the adhesive layer 40 between the second portion 22 and the covering member 30 is thinner than the thickness of the adhesive layer 40 between the first portion 21 and the covering member 30.

[0045] Furthermore, although the thickness of the adhesive layer 40 differs between the first region 21 and the second region 22, the total thickness of the resin layer 20 and the adhesive layer 40 is the same between the first region 21 and the second region 22. In other words, if the combined layer of the resin layer 20 and the adhesive layer 40 is considered to be a wiring layer, this wiring layer has a uniform thickness.

[0046] The adhesive layer 40 may be, for example, an optically clear adhesive (OCA) sheet or a liquid optically clear adhesive resin (OCR).

[0047] Next, a method for manufacturing the conductive film 1 according to the embodiment will be described with reference to Figures 3A to 3D. Figures 3A to 3D are diagrams for explaining each step of the method for manufacturing the conductive film 1.

[0048] First, as shown in Fig. 3A, a substrate 10 is prepared. In this embodiment, a transparent PET film is prepared as the substrate 10.

[0049] Next, as shown in FIG. 3B , a resin layer 20 having grooves 20 a is formed on the substrate 10. In this embodiment, the resin layer 20 having the grooves 20 a is formed by an imprinting method. In this case, the resin layer 20 made of a thermoplastic resin is formed on the substrate 10, the temperature is raised to soften the resin layer 20, a mold member (mold) that serves as a transfer plate is pressed against the resin layer 20, and the mold member is removed from the resin layer 20, thereby forming the resin layer 20 having the grooves 20 a. Note that this mold member has protrusions formed thereon that correspond to the grooves 20 a. In other words, the protrusions of the mold member press the thermoplastic resin to form the grooves 20 a.

[0050] Furthermore, in the present embodiment, when the resin layer 20 having the grooves 20a is produced by the imprinting method, the first portion 21 and the second portion 22 are formed in the resin layer 20. Specifically, by pressing a mold member against the thermoplastic resin, the first portion 21 and the second portion 22 having different thicknesses are formed in the resin layer 20. In this way, by using the imprinting method, the first portion 21 and the second portion 22 having different thicknesses can be formed in the resin layer 20, and at the same time, the grooves 20a can be formed in each of the first portion 21 and the second portion 22.

[0051] In this embodiment, the resin layer 20 having the grooves 20a is fabricated by a thermal imprinting method using a thermoplastic resin, but this is not limiting. For example, the resin layer 20 having the grooves 20a may be fabricated by a photoimprinting method using a photocurable resin. In this case, a liquid photocurable resin is sandwiched between a first mold member and a second mold member that serve as a transfer plate, and the photocurable resin is cured by irradiating it with light (ultraviolet rays). The first mold member and the second mold member are then removed. This allows the grooves 20a to be formed in the resin layer 20 made of the photocurable resin. Alternatively, the resin layer 20 having the grooves 20a may be formed using a thermosetting resin instead of a photocurable resin. These methods also allow the first region 21 and the second region 22 to be formed simultaneously with the grooves 20a.

[0052] 3C , metal wires 50 are formed in the resin layer 20. In this embodiment, the metal wires 50 are embedded in the grooves 20a of the resin layer 20. Specifically, a first metal wire 51 is embedded in the grooves 20a of the first portion 21 of the resin layer 20, and a second metal wire 52 is embedded in the grooves 20a of the second portion 22 of the resin layer 20. A method of forming the metal wires 50 in the grooves 20a of the resin layer 20 will be described later.

[0053] Next, as shown in FIG. 3D , the resin layer 20 on which the metal wires 50 are formed and the covering member 30 are bonded together by an adhesive layer 40. Specifically, the substrate 10 on which the resin layer 20 is laminated and the covering member 30 are bonded together by the adhesive layer 40. For example, when OCR is used as the material for the adhesive layer 40, the OCR can be applied onto the resin layer 20, and then the covering member 30 is placed on top of it and cured, thereby fixing the resin layer 20 and the covering member 30 together by the adhesive layer 40. This allows the adhesive layer 40 to fill the gap between the resin layer 20 and the covering member 30. In this embodiment, a cover glass is used as the covering member 30.

[0054] Let M1% and M2% be the area occupancy rates of the metal wires 50 (first metal wires 51) in the first portion 21 corresponding to the mesh region and M2% be the area occupancy rates of the metal wires 50 (second metal wires 52) in the second portion 22 corresponding to the wiring region, respectively. Let t1 and t2 be the thicknesses of the resin layer 20 in the first portion 21 and the second portion 22, respectively. These ratios preferably satisfy the following conditions: 0.5≦M1≦3%, 40≦M2≦60%, and 1.1≦t2 / t1≦1.3. This stabilizes the pressing force when bonding the covering member 30 to the resin layer 20. If the difference in thickness between the first portion 21 and the second portion 22 is too large (i.e., if the value of t2 / t1 becomes too large), the pressing force applied to the first portion 21 when bonding the covering member 30 to the resin layer 20 becomes unstable.

[0055] In this embodiment, when bonding the covering member 30 to the resin layer 20 with the adhesive layer 40, a long laminate film 15, in which the resin layer 20 is laminated on a long substrate 10, and the long film-like covering member 30 may be bonded together by lamination, as shown in FIG. 4 . For example, the long laminate film 15 and the long covering member 30 can be bonded together by roll-to-roll processing. After bonding the laminate film 15 and the covering member 30 together, the bonded laminate film 15 and covering member 30 are cut sequentially at predetermined positions. This allows multiple conductive films 1 to be continuously produced.

[0056] In this manner, the conductive film 1 can be produced in which the resin layer 20 formed on the substrate 10 and the covering member 30 are fixed together by the adhesive layer 40 .

[0057] Here, the details of the step of forming the metal wire 50 in the groove 20a of the resin layer 20 (the step of FIG. 3C) will be described with reference to FIGS. 5A to 5F. FIGS. 5A to 5F are diagrams for explaining the step of forming the metal wire 50 in the groove 20a of the resin layer 20.

[0058] First, as shown in Fig. 5B, a first metal film 50a is formed by vapor deposition or sputtering on a resin layer 20 having grooves 20a formed therein as shown in Fig. 5A. This results in the first metal film 50a being formed in the grooves 20a. Specifically, the first metal film 50a is formed as a thin film along the inner surfaces of the grooves 20a and the upper surface of the resin layer 20.

[0059] The first metal film 50a may be a metal nitride or a metal oxide containing at least one metal selected from the group consisting of Ti, Al, V, W, Ta, Si, Cr, Ag, Mo, Cu, Ni, and Zn. The first metal film 50a functions as an adhesive layer. The first metal film 50a also has the function of making the metal layer lines less visible.

[0060] Next, as shown in Fig. 5C, a second metal film 50b is formed on the first metal film 50a by vapor deposition or sputtering. This results in the second metal film 50b being formed in the groove 20a. Specifically, the thin second metal film 50b is formed on the first metal film 50a formed in the groove 20a and on the upper surface of the resin layer 20. The second metal film 50b functions as a seed layer (underlayer) for forming a metal layer 50c by plating in the next step.

[0061] The second metal film 50b may be made of a metal such as copper (Cu) or silver (Ag), or may be made of a conductive resin material or a transparent conductive material having light-transmitting properties such as indium tin oxide or tin oxide.

[0062] Next, as shown in FIG. 5D , a metal layer 50c is formed on the second metal film 50b. For example, using the second metal film 50b (seed layer) as a cathode, a metal such as copper (Cu) is laminated over the entire surface of the second metal film 50b by electroplating. Specifically, the metal layer 50c, which is a plated layer, is formed over the entire surface of the resin layer 20 so as to fill the grooves 20a. In this embodiment, copper is used as the metal layer 50c. In other words, the metal layer 50c is a copper plated layer. The metal layer 50c may also be formed by electroless plating.

[0063] Next, as shown in FIG. 5E , excess metal layer 50c formed outside of groove 20a is removed. As a result, metal layer 50c remains embedded only in groove 20a. Specifically, metal layer 50c, second metal film 50b, and first metal film 50a are removed until the surface of resin layer 20 in the areas where groove 20a is not formed is exposed. In other words, unnecessary portions of metal layer 50c, second metal film 50b, and first metal film 50a are removed while leaving metal layer 50c, second metal film 50b, and first metal film 50a embedded in groove 20a. This results in resin layer 20 in which metal wires 50 composed of first metal film 50a, second metal film 50b, and metal layer 50c embedded in groove 20a. When metal layer 50c is copper, metal wire 50 is copper wiring primarily composed of copper.

[0064] 5F, a blackening treatment may be performed to blacken the surface of the metal layer 50c to form a blackened layer 50d, and an anti-rust film may be formed on the surface of the blackened layer 50d by performing an anti-rust treatment thereafter.

[0065] Next, the effects of the conductive film 1 according to the present embodiment will be described in comparison with a comparative conductive film 1X. Fig. 6 is a partial cross-sectional view of the comparative conductive film 1X.

[0066] As shown in Figure 6, the comparative conductive film 1X includes a substrate 10, a resin layer 20X laminated on the substrate 10, metal wires 50 (first metal wire 51, second metal wire 52) embedded in grooves in the resin layer 20X, a covering member 30 arranged above the resin layer 20X, and an adhesive layer 40X that bonds the resin layer 20X and the covering member 30 together.

[0067] In the comparative example conductive film 1X, as in the conductive film 1 of the present embodiment, the area occupancy rate of the metal wire 50 (second metal wire 52) formed in the ineffective region 1b corresponding to the wiring region is greater than the area occupancy rate of the metal wire 50 (first metal wire 51) formed in the effective region 1a corresponding to the mesh region.

[0068] On the other hand, in the comparative conductive film 1X, unlike the conductive film 1 according to the present embodiment, the resin layer 20X has a uniform thickness, and the adhesive layer 40X also has a uniform thickness.

[0069] In the comparative conductive film 1X configured as described above, the adhesive layer 40X may thermally expand or contract due to the influence of external heat, and the covering member 30 may peel off from the resin layer 20X.

[0070] Furthermore, since the metal wires 50 made of a metal such as copper have poor adhesion to the adhesive layer 40X, if the area occupancy of the metal wires 50 formed in the ineffective region 1b (wiring region) is larger than the area occupancy of the metal wires 50 formed in the effective region 1a (mesh region), adhesion is unstable when bonding the covering member 30 to the resin layer 20X. For this reason, peeling is likely to occur in the ineffective region 1b (wiring region), where the area occupancy of the metal wires 50 is relatively high. In particular, since the ineffective region 1b is the outer periphery of the conductive film 1X, if there are parts of the ineffective region 1b with poor adhesion, peeling is likely to occur from these parts.

[0071] In contrast, in the conductive film 1 of this embodiment, although the area occupancy rate of the metal wire 50 (first metal wire 51) in the effective region 1a is smaller than the area occupancy rate of the metal wire 50 (second metal wire 52) in the ineffective region 1b, the thickness of the second portion 22 of the resin layer 20 corresponding to the ineffective region 1b is thicker than the thickness of the first portion 21 of the resin layer 20 corresponding to the effective region 1a, so the thickness of the adhesive layer 40 located between the second portion 22 and the covering member 30 is thinner than the thickness of the adhesive layer 40 located between the first portion 21 and the covering member 30.

[0072] This allows the adhesive layer 40 to be made thinner in the second region 22 (ineffective region 1b) where the area occupancy of the metal wires 50, which have poor adhesion to the adhesive layer 40, is high. Therefore, the influence of thermal expansion or thermal contraction of the adhesive layer 40 can be reduced, and peeling of the covering member 30 from the resin layer 20 can be suppressed. As a result, adhesion can be stabilized in the second region 22 (ineffective region 1b) where the area occupancy of the metal wires 50 is high. Therefore, a conductive film 1 with high adhesion reliability can be realized.

[0073] In the conductive film 1 according to this embodiment, the total thickness of the resin layer 20 and the adhesive layer 40 is the same in the first region 21 and the second region 22 .

[0074] With this configuration, the covering member 30 is arranged parallel to the substrate 10, and can be adhered to the resin layer 20 without leaving a gap between the covering member 30 and the resin layer 20. This makes it possible to prevent air from entering between the resin layer 20 and the covering member 30 (occurrence of air entrapment), and further improves the adhesion reliability of the conductive film 1.

[0075] Furthermore, in the conductive film 1 according to the present embodiment, the line width of the first metal wire 51 is smaller than the line width of the second metal wire 52. In other words, the line width of the second metal wire 52 is larger than the line width of the first metal wire 51.

[0076] With this configuration, even if the area occupancy rate of the metal wire 50 in the second portion 22 becomes larger than the area occupancy rate of the metal wire 50 in the first portion 21 due to the second metal wire 52 having a large line width, by making the adhesive layer 40 in the second portion 22 thinner, peeling of the covering member 30 can be suppressed and adhesion reliability can be maintained.

[0077] In the conductive film 1 according to the present embodiment, the second portion 22 is provided along the outer periphery of the substrate 10. Specifically, the second portion 22 is provided in a frame shape in the ineffective region 1b (wiring region).

[0078] This configuration can improve adhesion reliability even in products (such as touch panels) that have ineffective areas 1b where the covering member 30 is likely to peel off.

[0079] In the conductive film 1 according to the above embodiment, the second region 22 provided in the ineffective region 1b is provided outside the first region 21, but this is not limiting. For example, as in the conductive film 1A shown in Figures 7 and 8, the second region 22 may be provided inside the first region 21. In other words, the second region 22 may be provided not only in the ineffective region 1b but also partially within the effective region 1a. Figure 7 is a plan view of the conductive film 1A according to Modification 1, and Figure 8 is a partial cross-sectional view of the conductive film 1A when cut along line VIII-VIII in Figure 7.

[0080] 7 , in this modification, the second portion 22 of the resin layer 20 is provided linearly inside the first portion 21. Note that the second portion 22 may also be provided in an island shape inside the first portion 21.

[0081] In this way, by providing the second portions 22 in areas other than the ineffective area 1b, the adhesive layer 40 can be thinned in the portions corresponding to the second portions 22. Specifically, the adhesive layer 40 can be thinned partially in the second portions 22 in the effective area 1a as well. This ensures adhesion not only in the ineffective area 1b but also in the effective area 1a.

[0082] In the above embodiment, the first metal wires 51 are formed in a mesh shape across the entire effective area 1a (first portion 21), but in this modification, the first metal wires 51 are formed in a mesh shape in each of the plurality of rectangular electrode areas, as shown in Figures 7 and 8. Therefore, when the conductive film 1A is used in a touch panel, the mesh-shaped first metal wires 51 formed in each of the plurality of electrode areas can be used as sensor electrodes.

[0083] The conductive film 1A in this modification may be used for purposes other than a touch panel. For example, the conductive film 1A may be used in a transparent display. Furthermore, the first metal wires 51 formed in a mesh shape may be used as an antenna or a heater.

[0084] In the conductive film 1 of the above embodiment, the resin layer 20 and the covering member 30 on which the metal wires 50 are formed are formed on only one side of the substrate 10, but this is not limited thereto. For example, as in the conductive film 1B shown in Fig. 9, the resin layer 20 and the covering member 30 on which the metal wires 50 are formed may be formed on both sides of the substrate 10. Fig. 9 is a partial cross-sectional view of a conductive film 1B according to Modification 2.

[0085] Specifically, as shown in Figure 9, the conductive film 1B of this modified example has the resin layer 20 as the first resin layer, the covering member 30 as the first covering member, and the adhesive layer 40 as the first adhesive layer, and further has a second resin layer 60 arranged below the substrate 10, a second covering member 70 arranged below the second resin layer 60, and a second adhesive layer 80 located between the second resin layer 60 and the second covering member 70 and adhering the second resin layer 60 and the second covering member 70 together.

[0086] The second resin layer 60 includes, as the metal wires 90, a third metal wire 91 and a fourth metal wire 92 having different line widths. Specifically, the third metal wire 91 and the fourth metal wire 92 are embedded in grooves 60a formed in the second resin layer 60. In this embodiment, the line width of the third metal wire 91 is smaller than the line width of the fourth metal wire 92. The second resin layer 60 also includes a third region 61 and a fourth region 62 that is thicker than the third region 61. The third metal wire 91 is provided in the third region 61 as a third conductor, and the fourth metal wire 92 is provided in the fourth region 62 as a fourth conductor. The third metal wire 91 and the fourth metal wire 92 are in contact with the second adhesive layer 80. In a plan view of the conductive film 1B, the area occupancy rate of the third metal wire 91 in the third region 61 is smaller than the area occupancy rate of the fourth metal wire 92 in the fourth region 62. The thickness of the second adhesive layer 80 between the fourth portion 62 and the second covering member 70 is thinner than the thickness of the second adhesive layer 80 between the third portion 61 and the second covering member 70 .

[0087] According to the conductive film 1B of this modified example configured as described above, the adhesive layer 40 can be thinned at the second region 22 (invalid region 1b) on the upper surface of the substrate 10, where the area occupancy of the metal wires 50 is high. Furthermore, the second adhesive layer 80 can be thinned at the fourth region 62 (invalid region 1b) on the lower surface of the substrate 10, where the area occupancy of the metal wires 90 is high. This reduces the effects of thermal expansion or thermal contraction of the adhesive layer 40 and the second adhesive layer 80, thereby preventing the covering member 30 from peeling from the resin layer 20 and preventing the second covering member 70 from peeling from the second resin layer 60. In other words, peeling of the covering member 30 and the second covering member 70 can be effectively prevented on both surfaces of the substrate 10. Furthermore, a conductive film 1B with high adhesion reliability can be realized on both surfaces of the substrate 10.

[0088] In the conductive film 1B of this modified example, the structure of both sides of the substrate 10 is vertically symmetrical. Therefore, the first portion 21 of the resin layer 20 on the upper surface of the substrate 10 and the third portion 61 of the second resin layer 60 on the lower surface of the substrate 10 overlap vertically. Similarly, the second portion 22 of the resin layer 20 on the upper surface of the substrate 10 and the fourth portion 62 of the second resin layer 60 on the lower surface of the substrate 10 overlap vertically. Furthermore, the second resin layer 60, the second covering member 70, the second adhesive layer 80, the third metal wire 91, and the fourth metal wire 92 have the same shapes as the resin layer 20, the covering member 30, the adhesive layer 40, the first metal wire 51, and the second metal wire 52, and can be made of the same materials. In other words, the conductive film 1B has a double-sided mesh structure in which metal wires are formed in a mesh pattern on both surfaces. When the conductive film 1B configured in this manner is used in a touch sensor, the first metal wire 51 on one surface can be used as an Rx electrode, and the third metal wire 91 on the other surface can be used as a Tx electrode. In other words, the Rx electrode and the Tx electrode of the touch electrode can be formed separately on both surfaces.

[0089] (Other Modifications) Although the conductive film according to the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

[0090] For example, in the above embodiment, the metal wires 50 (first metal wire 51, second metal wire 52) are embedded in the grooves 20a of the resin layer 20, but this is not limiting. Specifically, the metal wires 50 (first metal wire 51, second metal wire 52) may be formed on the flat upper surface of the resin layer 20 without forming the grooves 20a in the resin layer 20.

[0091] In the above embodiment, the first directional wires 51 a and the second directional wires 51 b constituting the mesh-shaped first metal wires 51 are formed to be integrated at the intersections, but this is not limited thereto. For example, two resin layers 20 may be stacked, with the first directional wires 51 a formed in one of the two resin layers 20 and the second directional wires 51 b formed in the other of the two resin layers 20, and the first directional wires 51 a and the second directional wires 51 b may be formed to cross each other at an intersection such that they do not come into contact with each other.

[0092] In the above embodiment, the conductive film 1 is used as a touch sensor substrate in a touch panel, but the present invention is not limited thereto. For example, the light-transmitting conductive film 1 may be used as a mounting substrate for mounting electronic components such as LED elements or circuit elements, as a connection substrate for electrically connecting electronic components, as an antenna substrate having wiring formed in a predetermined pattern as a pattern antenna such as a 5G antenna, or as a heater substrate using a metal wire as a heating wire.

[0093] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would occur to those skilled in the art, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. Furthermore, the present disclosure also includes any combination of two or more claims from among the multiple claims set forth in the claims at the time of filing, within the scope of technical compatibility. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of technical compatibility, the present disclosure also includes all combinations of claims included in that multiple claim or multiple multiple multiple claims.

[0094] The conductive film according to the present disclosure can be used in various electrical devices, including touch panels.

[0095] REFERENCE SIGNS LIST 1, 1A, 1B Conductive film 1a Effective area 1b Ineffective area 2 Flexible wiring board 10 Base material 15 Laminated film 20 Resin layer 20a Groove 21 First portion 22 Second portion 30 Covering member 40 Adhesive layer 50 Metal wire 50a First metal film 50b Second metal film 50c Metal layer 50d Blackened layer 51 First metal wire 51a First directional wire 51b Second directional wire 52 Second metal wire 60 Second resin layer 60a Groove 61 Third portion 62 Fourth portion 70 Second covering member 80 Second adhesive layer 90 Metal wire 91 Third metal wire 92 Fourth metal wire

Claims

1. A conductive film comprising: a substrate; a resin layer disposed above the substrate; a coating member disposed above the resin layer; and an adhesive layer located between the resin layer and the coating member and adhering the resin layer and the coating member, wherein the resin layer has a first portion and a second portion having a thickness greater than that of the first portion, a first conductor is provided in the first portion, and a second conductor is provided in the second portion, the first conductor and the second conductor are in contact with the adhesive layer, in a planar view of the conductive film, an area occupancy rate of the first conductor in the first portion is smaller than an area occupancy rate of the second conductor in the second portion, and a thickness of the adhesive layer located between the second portion and the coating member is thinner than a thickness of the adhesive layer located between the first portion and the coating member.

2. The conductive film according to claim 1, wherein a total thickness of the resin layer and the adhesive layer is the same in the first region and in the second region.

3. The conductive film according to claim 1, wherein the first conductor and the second conductor are metal lines, and the line width of the first conductor is smaller than the line width of the second conductor.

4. The conductive film according to claim 1, wherein the second portion is provided along the outer periphery of the substrate.

5. The conductive film according to claim 1, wherein the second portion is provided in an island or line shape inside the first portion.

6. The conductive film according to claim 1, wherein the resin layer is a first resin layer, the covering member is a first covering member, and the adhesive layer is a first adhesive layer, the conductive film further comprises: a second resin layer disposed below the base material, a second covering member disposed below the second resin layer, and a second adhesive layer located between the second resin layer and the second covering member and adhering the second resin layer and the second covering member, the second resin layer having a third portion and a fourth portion having a thickness greater than that of the third portion, a third conductor is provided in the third portion, and a fourth conductor is provided in the fourth portion, the third conductor and the fourth conductor are in contact with the second adhesive layer, in a planar view of the conductive film, an area occupancy rate of the third conductor in the third portion is smaller than an area occupancy rate of the fourth conductor in the fourth portion, and a thickness of the second adhesive layer between the fourth portion and the second covering member is thinner than a thickness of the second adhesive layer between the third portion and the second covering member.

7. A conductive film according to any one of claims 1 to 6, wherein the first conductor is embedded in a groove provided in the first portion, and the second conductor is embedded in a groove provided in the second portion.

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