Conductive film and display device

Abstract

This invention relates to a conductive film comprising a film-shaped substrate and a conductive layer disposed on a main surface of the substrate. The conductive layer comprises a first metal layer containing a first metal and a second metal layer containing a second metal different from the first metal, disposed sequentially from the substrate side. The first metal layer includes grain boundaries.

Description

Technical Field

[0001] This disclosure relates to a conductive film and a display device. Background Technology

[0002] Transparent antennas, sometimes mounted on a conductive substrate (conductive film) with transparency and conductivity, are sometimes installed on the surface of touch panels or displays. Recently, with the increasing size and diversity of touch panels and displays, the conductive film requires high transparency and conductivity, as well as flexibility.

[0003] As a conductive substrate, for example, Patent Document 1 discloses a conductive substrate comprising a substrate, a base layer, a trench forming layer, and a conductive pattern layer. The base layer has a mixed region formed from a surface of the conductive pattern layer to its inner side, including metal constituting the conductive pattern layer and metal particles entering the base layer. It also discloses that the conductive pattern layer can be formed from multiple metal layers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-29658 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] For conductive films having conductive layers composed of multiple metal layers, high adhesion between the metal layers is desirable.

[0009] Technical solutions for solving technical problems

[0010] One aspect of this disclosure relates to a conductive film comprising a film-like substrate and a conductive layer disposed on a main surface of the substrate. In this conductive film, the conductive layer has a first metal layer and a second metal layer sequentially disposed from the substrate side. The first metal layer includes grain boundaries.

[0011] Another aspect of this disclosure relates to a display device having a conductive film.

[0012] The effects of the invention

[0013] Regarding conductive films with conductive layers composed of multiple metal layers, the adhesion between the metal layers can be improved. Attached Figure Description

[0014] Figure 1 This is a schematic top view illustrating one embodiment of a conductive film.

[0015] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0016] Figure 3 yes Figure 2 A magnified view of a portion of the conductive film shown.

[0017] Figure 4 It is a schematic representation. Figure 1 A cross-sectional view of the method for manufacturing the conductive film shown.

[0018] Figure 5 It is a schematic representation. Figure 1 A cross-sectional view of the method for manufacturing the conductive film shown.

[0019] Figure 6 It is a schematic representation. Figure 1 A cross-sectional view of the method for forming the metal layer of the conductive film shown.

[0020] Figure 7 This is a cross-sectional view showing one embodiment of the display device. Detailed Implementation

[0021] This disclosure is not limited to the following examples.

[0022] Figure 1 This is a schematic top view illustrating one embodiment of a conductive film. Figure 2 It is along Figure 1 A sectional view along line II-II. Figure 1 and Figure 2 The conductive film 100 shown includes: a film-shaped substrate 1; a first resin layer 10 disposed on the substrate 1; a second resin layer 20 disposed on the first resin layer 10 and having a linear trench 25 opening on a surface opposite to the first resin layer 10; and a conductive layer 30 disposed in the trench 25. Figure 1 and Figure 2 In this example, a mesh pattern is formed by the intersecting of multiple linear trenches 25 extending in two directions. The conductive layer 30 within the trenches 25 also forms a mesh pattern. The conductive layer 30 with the mesh pattern can function well as a radiating element of an antenna, for example. The trenches 25 and the conductive layer 30 are disposed over a portion of the surface 10S of the first resin layer 10.

[0023] Figure 3 yes Figure 2 An enlarged view of region R in the cross-sectional view of the conductive film 100 shown. (See diagram below.) Figure 3As shown, the conductive layer 30 has a first metal layer 30a containing a first metal, a third metal layer 30c containing a third metal, and a second metal layer 30b containing a second metal, sequentially disposed from the substrate 1 side. The first metal, the second metal, and the third metal are metals of different kinds. The first metal, the second metal, and the third metal can each be a single metal, or a combination of two or more metals. The first metal layer 30a may also contain a second metal and / or a third metal, the second metal layer 30b may also contain a first metal and / or a third metal, and the third metal layer 30c may also contain a first metal and / or a second metal. The first metal layer 30a, the second metal layer 30b, and the third metal layer 30c may also contain non-metallic elements such as phosphorus within the range of maintaining conductivity.

[0024] The first metal constituting the first metal layer 30a may be, for example, at least one selected from nickel, gold, silver, copper, palladium, or nickel.

[0025] The first metal layer 30a comprises multiple grains, and grain boundaries 31, serving as their boundaries, are formed within the first metal layer 30a. The formation of grain boundaries 31 increases the surface area of ​​the first metal layer 30a, which can contribute to improving the adhesion between the first metal layer 30a and other metal layers. For example, the formation of grain boundaries 31 can be confirmed by observing a cross-section of the conductive film 100 along its thickness direction using TEM (transmission electron microscopy). In elemental mapping of the first metal layer 30a, grain boundaries 31 are sometimes observed as linear regions within the first metal layer 30a where the first metal is not substantially observed. In this case, the first metal layer 30a can also be divided into multiple regions by the grain boundaries 31. Each region divided by the grain boundaries 31 is considered equivalent to a grain, and its maximum width can be, for example, greater than 10 nm or greater than 20 nm, or less than 100 nm or less than 80 nm.

[0026] From the viewpoint of high adhesion between the first metal layer 30a and other metal layers (e.g., the third metal layer 30c), the thickness of the first metal layer 30a can be 10 nm or more, 20 nm or more, or 30 nm or more. From the viewpoint of high conductivity as a conductive layer 30, the thickness of the first metal layer 30a can be 200 nm or less, 100 nm or less, or 90 nm or less. The thickness of the portion of the conductive layer 30 containing the first metal can be considered as the thickness of the first metal layer 30a.

[0027] The second metal constituting the second metal layer 30b may be, for example, at least one selected from copper, gold, silver, palladium, or copper.

[0028] The second metal can also exist at the grain boundaries 31 within the first metal layer 30a. That is, the metallic composition of the second metal can also penetrate the grain boundaries 31 within the first metal layer 30a. The second metal can also be continuously distributed from the second metal layer 30b to the grain boundaries 31 within the first metal layer 30a. The second metal existing at the grain boundaries 31 can be considered as part of the first metal layer 30a. By having the second metal present at the grain boundaries 31, for example, the adhesion between the first metal layer 30a and the second metal layer 30b can be further improved using an anchoring effect. The presence of the second metal at the grain boundaries 31 can be confirmed by using elemental mapping with EDS-STEM.

[0029] From the viewpoint of high conductivity, the thickness of the second metal layer 30b can be 1.5 μm or more, 1.8 μm or more, or 2.0 μm or more. The thickness of the second metal layer 30b can also be 10 μm or less, 8 μm or less, or 6 μm or less. The thickness of the portion of the conductive layer 30 containing the second metal can be considered as the thickness of the second metal layer 30b. However, the thickness of the second metal present at the grain boundary 31 is not included in the thickness of the second metal layer 30b.

[0030] Conductive layer 30 can be as Figure 3 The diagram shows a third metal layer 30c further disposed between the first metal layer 30a and the second metal layer 30b, or it may not have a third metal layer 30c. The third metal constituting the third metal layer 30c may be, for example, at least one selected from palladium, gold, silver, and copper, or palladium. The third metal layer 30c may also be formed from metal particles containing the third metal.

[0031] The third metal can also exist at the grain boundary 31. That is, the metallic component of the third metal can also penetrate the grain boundary 31 in the first metal layer 30a. The third metal can also be continuously distributed from the third metal layer 30c to the grain boundary 31 in the first metal layer 30a. The third metal existing at the grain boundary 31 can be regarded as part of the first metal layer 30a. By having the third metal exist at the grain boundary 31, for example, the adhesion between the first metal layer 30a and the third metal layer 30c can be improved by utilizing the anchoring effect. The existence of the third metal at the grain boundary 31 can be confirmed by using elemental mapping of EDS-STEM analysis.

[0032] From the viewpoint of superior adhesion between the first metal layer 30a and the third metal layer 30c, the depth of the third metal present at the grain boundary 31 from the surface of the first metal layer 30a can be at most 40 nm or more, 30 nm or more, or 20 nm or more. From the viewpoint of high conductivity of the conductive layer 30, the depth of the third metal present at the grain boundary 31 from the surface of the first metal layer 30a can be less than 200 nm or less.

[0033] From the viewpoint of facilitating the growth of a metal coating on the third metal layer 30c and achieving a higher adhesion between the third metal layer 30c and the second metal layer 30b, the thickness of the third metal layer 30c can be 10 nm or more, 15 nm or more, or 20 nm or more. From the viewpoint of high conductivity as a conductive layer 30, the thickness of the third metal layer 30c can be 30 nm or less, 25 nm or less, or 20 nm or less. The thickness of the portion of the conductive layer 30 containing the third metal can be considered as the thickness of the third metal layer 30c. However, the thickness of the third metal present at the grain boundary 31 is not included in the thickness of the third metal layer 30c.

[0034] The third metal layer 30c may also have a thickness smaller than either the thickness of the first metal layer 30a or the thickness of the second metal layer 30b. The first metal layer 30a may also have a thickness smaller than the thickness of the second metal layer 30b. As a result, the conductive film 100 can easily have better adhesion and better conductivity between the metal layers.

[0035] The electrical conductivity of the second metal in the second metal layer 30b, the electrical conductivity of the first metal in the first metal layer 30a, and the electrical conductivity of the third metal in the third metal layer 30c can also increase sequentially. Therefore, the conductive film 100 easily possesses excellent electrical conductivity.

[0036] The conductive layer 30 may also have a fourth metal layer on the second metal layer 30b, comprising a metal different from the second metal. The metal constituting the fourth metal layer may, for example, include at least one of gold or palladium.

[0037] The conductive layer 30 may also have a pattern including linear portions. The pattern of the conductive layer 30 may also include multiple linear portions arranged while extending along a certain direction. The conductive layer 30 may also have a mesh pattern including linear portions.

[0038] The width of the linear portion of the conductive layer 30 can be 1 μm or more, 10 μm or more, or 20 μm or more, or it can be 90 μm or less, 70 μm or less, or 30 μm or less. In this specification, the width of the linear portion of the conductive layer 30 is referred to as the maximum width in the extending direction of the linear portion. From the viewpoint of improving the transparency of the conductive film 100, the width of the linear portion of the conductive layer 30 can also be 0.3 μm or more, 0.5 μm or more, or 1.0 μm or more, or it can be 5.0 μm or less, 4.0 μm or less, or 3.0 μm or less.

[0039] The thickness of the conductive layer 30 can be 0.1 μm or more, 1.0 μm or more, or 2.0 μm or more, or less than 10.0 μm, 5.0 μm or less, or 3.0 μm or less. The width and thickness of the conductive layer 30 can be adjusted by changing the design of the mold 50 (described later) and changing the width and thickness of the groove 25.

[0040] The aspect ratio of the conductive layer 30 can be, for example, 0.1 or more, 0.5 or more, or 1.0 or more, and can be 10.0 or less, 7.0 or less, or 4.0 or less. The aspect ratio of the conductive layer 30 refers to the ratio of the thickness of the conductive layer 30 to the width of the conductive layer 30 (thickness / width).

[0041] Substrate 1 can also be a transparent substrate, particularly a transparent resin film. The resin film can be, for example, a film of polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), cyclic olefin polymer (COP), or polyimide (PI). Substrate 1 can also be glass or a Si wafer, etc. Substrate 1 can also have the level of light transmittance required for incorporating the conductive film 100 into the display device. Specifically, the total light transmittance of the substrate can be 90-100%. The haze of the substrate can also be 0-5%.

[0042] The thickness of substrate 1 can be 10μm or more, 20μm or more, or 35μm or more, or it can be less than 500μm, less than 200μm or less than 100μm.

[0043] The first resin portion 12 constituting the first resin layer 10 may also be a cured product of a curable resin composition containing a curable resin. The first resin layer 10 may also be transparent. Examples of curable resins include amino resins, cyanate resins, isocyanate resins, polyimide resins, epoxy resins, oxetane resins, polyesters, allyl resins, phenolic resins, benzoxazine resins, xylene resins, ketone resins, furan resins, COPNA resins, silicone resins, dicyclopentadiene resins, benzocyclobutene resins, cyclic sulfur resins, olefin-thiol resins, polymethylimide resins, polyvinylbenzyl ether compounds, acenaphthene, and UV-curable resins containing functional groups such as unsaturated double bonds, cyclic ethers, and vinyl ethers that undergo polymerization reactions under ultraviolet light. The curable resin may be a single type or a combination of two or more.

[0044] The first inorganic particles 11 are dispersed within the first resin portion 12. Examples of the first inorganic particles 11 include silicon dioxide, aluminum oxide, titanium dioxide, tantalum oxide, zirconium oxide, silicon nitride, barium titanate, barium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, lead titanate, lead zirconate titanate, lanthanum lead zirconate titanate, gallium oxide, spinel, malachite, cordierite, talc, aluminum titanate, barium silicate, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, zinc oxide, magnesium titanate, hydrotalcite, mica, calcined kaolin, and carbon. The first inorganic particles 11 can be a single type or a combination of two or more.

[0045] The shape of the first inorganic particle 11 is not particularly limited, and it can also be, for example, spherical, ellipsoidal, polyhedral, plate-like, scaly, columnar, etc.

[0046] A portion of the plurality of first inorganic particles 11 may also be present in the first metal layer 30a. The first inorganic particles 11a present in the first metal layer 30a may partially protrude from the first resin portion 12, or may separate from the first resin portion 12 and be distributed within the first metal layer 30a. The first inorganic particles 11a partially protruding from the first resin portion 12 or leaving the first resin portion 12 are located within the first metal layer 30a, resulting in the first metal of the first metal layer 30a existing around the protruding or leaving portion. That is, a portion of the plurality of first inorganic particles 11 may also partially protrude from the first resin portion 12 and / or separate from the first resin portion 12 and be surrounded by the first metal within the first metal layer 30a. Furthermore, being surrounded by the first metal includes not only being surrounded by the first metal, but also being surrounded by the first metal, the grain boundaries 31 contained in the first metal layer 30a, and the second and third metals present at the grain boundaries 31. The first inorganic particles 11a leaving the first resin portion 12 can be considered as part of the first metal layer 30a. By including the first inorganic particles 11a in the first metal layer 30a, the adhesion between the first resin layer 10 and the first metal layer 30a can be further improved. In addition, if the first inorganic particles 11a are present in the first metal layer 30a, grain boundaries 31 are easily formed within the first metal layer 30a.

[0047] At least a portion of the plurality of first inorganic particles 11 may also partially protrude from the first resin portion 12 to the side of the second resin layer 20. "The first inorganic particles 11 partially protrude from the first resin portion 12 to the side of the second resin layer 20" means that a portion of the surface of the first inorganic particle 11 protrudes from the first resin portion 12 to the side of the second resin layer 20 and is in contact with the second resin layer 20. That is, the plurality of first inorganic particles 11 that partially protrude to the side of the second resin layer 20 may also be in a state where the portion protruding to the side of the second resin layer 20 is not covered by the first resin portion 12 (the portion protruding to the side of the second resin layer 20 is exposed from the first resin portion 12). Hereinafter, such first inorganic particles will also be referred to as "exposed first inorganic particles". The exposed first inorganic particles 11a can contribute to improving the adhesion between the first resin layer 10 and the second resin layer 20. For example, the presence of exposed first inorganic particles 11a can be confirmed by observing a cross-section of the conductive film 100 along the thickness direction using TEM. The first inorganic particles 11 may also include first inorganic particles 11b embedded in the first resin portion 12 and not protruding to the side of the second resin layer 20 (not exposed from the first resin portion 12).

[0048] From the viewpoint of excellent adhesion between the first resin layer 10 and the second resin layer 20 of the conductive film 100, the proportion of the number of exposed first inorganic particles 11a relative to the total number of first inorganic particles 11 can be 10% or more. For example, the proportion of the number of exposed first inorganic particles 11a relative to the total number of first inorganic particles 11 can also be 40% or less. The proportion of the number of exposed first inorganic particles 11a can be calculated by measuring the number of exposed first inorganic particles 11a in a cross-sectional image of the first resin layer 10 within a 1.5 μm range in any extension direction of the conductive film 100, and the total number of first inorganic particles 11 in that range.

[0049] Multiple first inorganic particles 11 may also be biased towards the second resin layer 20 in the first resin layer 10. It can be confirmed by observing a cross-section of the conductive film 100 along the thickness direction using TEM that the first inorganic particles 11 are biased towards the second resin layer 20 in the first resin layer 10.

[0050] "A plurality of first inorganic particles 11 are biased towards the second resin layer 20 in the first resin layer 10" means, for example, that in a cross-section of the conductive film 100 along the thickness direction, when region A is defined as the area from the center of the first resin layer 10 in the thickness direction to the side of the second resin layer 20, the proportion of the number of first inorganic particles 11 present in region A (including exposed first inorganic particles 11a) is greater than 50% relative to the total number of first inorganic particles 11 in the entire first resin layer 10. This proportion may also be 60% or more, 70% or more, 75% or more, or 80% or more.

[0051] The average particle size of the first inorganic particles 11 can be, for example, 10 nm or more, 15 nm or more, or 20 nm or more, or 400 nm or less, 300 nm or less, or 200 nm or less. By observing a cross-section of the conductive film 100 along its thickness direction using TEM, the maximum length of each of the first inorganic particles 11 existing in a range of 1.5 μm in any extension direction of the conductive film 100 is measured in the TEM image of the cross-section and averaged, thereby calculating the average particle size of the first inorganic particles 11.

[0052] The thickness of the first resin layer 10 or the first resin part 12 can be, for example, 30 nm or more, 50 nm or more, or 100 nm or more, or it can be less than 500 nm, less than 400 nm or less, or less than 300 nm.

[0053] The second resin layer 20 is a resin layer mainly composed of the second resin portion 22. The second resin portion 22 may also be transparent. The second resin portion 22 may also be a cured product of a photocurable resin or a thermocurable resin. Examples of photocurable resins or thermocurable resins include acrylic resins, amino resins, cyanate ester resins, isocyanate ester resins, polyimide resins, epoxy resins, oxetane resins, polyesters, allyl resins, phenolic resins, benzoxazine resins, xylene resins, ketone resins, furan resins, COPNA resins, silicone resins, dicyclopentadiene resins, benzocyclobutene resins, cyclic sulfur resins, olefin-thiol resins, polymethylene imine resins, polyvinyl benzyl ether compounds, acenaphthene, and UV-curable resins containing functional groups such as unsaturated double bonds, cyclic ethers, and vinyl ethers that undergo polymerization reactions under ultraviolet light. These photocurable resins or thermocurable resins may be a single type or a combination of two or more.

[0054] The second resin layer 20 may also contain second inorganic particles. The second inorganic particles may be one or more inorganic particles selected from Pd, Cu, Ni, Co, Au, Ag, Pd, Rh, Pt, In, and Sn, and may also contain Pd. The second inorganic particles may be a single type or a combination of two or more inorganic particles. The second inorganic particles may also be contained in the first metal layer 30a.

[0055] The shape of the second inorganic particles is not particularly limited, and can also be, for example, spherical, ellipsoidal, polyhedral, plate-like, scaly, columnar, etc.

[0056] From the viewpoint of excellent transparency of the conductive film 100, the average particle size of the second inorganic particles can be less than 10 nm, less than 8 nm, or less than 5 nm. The average particle size of the second inorganic particles can also be, for example, greater than 0.1 nm, greater than 0.5 nm, or greater than 1 nm. By observing a cross-section of the conductive film 100 along its thickness direction using TEM, the maximum length of each of the second inorganic particles existing in a range of 1.5 μm in any extension direction of the conductive film 100 is measured in the TEM image of the cross-section and averaged, thereby calculating the average particle size of the second inorganic particles.

[0057] The average particle size of the second inorganic particle can also be smaller than the average particle size of the first inorganic particle 11. The ratio of the average particle size of the second inorganic particle to the average particle size of the first inorganic particle 11 (average particle size of the second inorganic particle / average particle size of the first inorganic particle 11) can be less than 0.3 or less than 0.1, or it can be more than 0.01, more than 0.02 or more than 0.05.

[0058] Multiple second inorganic particles may also be biased towards the first resin layer 10 within the second resin layer 20. "Multiple second inorganic particles biased towards the first resin layer 10 within the second resin layer 20" means, for example, in a TEM image of a cross-section of the conductive film 100 along its thickness direction, where region B is defined as the area from the center of the second resin layer 20 in the thickness direction to the side of the first resin layer 10, the proportion of second inorganic particles in region B exceeds 50% relative to the total number of second inorganic particles in the entire second resin layer 20. This proportion may also be 80% or more, 90% or more, or 95% or more.

[0059] From the viewpoint of the excellent transparency of the conductive film 100, the second inorganic particles, comprising 80% or more of the total number of second inorganic particles, can also be distributed in a region where the distance from the interface between the first resin layer 10 and the second resin layer 20 is less than 1 / 3, 1 / 4, or 1 / 5 of the thickness of the first resin layer 10. Similarly, the second inorganic particles, comprising 90% or more or 95% or more of the total number of second inorganic particles, can also be distributed in a region where the distance from the interface between the first resin layer 10 and the second resin layer 20 is less than 1 / 3, 1 / 4, or 1 / 5 of the thickness of the first resin layer 10. "The interface between the first resin layer 10 and the second resin layer 20" refers to the interface between the first resin portion 12 and the second resin portion 22, and the interface between the exposed first inorganic particles 11a and the second resin portion 22.

[0060] From the viewpoint of the excellent transparency of the conductive film 100, the second inorganic particles, comprising more than 80% of the total number of the second inorganic particles, can also be distributed in a region at a distance of 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less from the interface between the first resin layer 10 and the second resin layer 20. Similarly, the second inorganic particles, comprising more than 90% or 95% of the total number of the second inorganic particles, can also be distributed in a region at a distance of 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less from the interface between the first resin layer 10 and the second resin layer 20.

[0061] Multiple second inorganic particles may also exist around the portions of each of the exposed first inorganic particles 11a that protrude (expose) towards the second resin layer 20. In this case, the adhesion between the first resin layer 10 and the second resin layer 20 can be further improved. "Around the portions of each of the first inorganic particles 11a that protrude towards the second resin layer 20" can also refer to a region within 10 nm from the surface of the portion of the first inorganic particle 11a protruding towards the second resin layer 20. Multiple second inorganic particles may also be in contact with the exposed portion of one first inorganic particle 11a protruding towards the second resin layer 20.

[0062] The trench 25 opens on a surface opposite to the first resin layer 10 and extends over the second resin layer 20. The trench 25 includes portions forming a pattern corresponding to the pattern of the conductive layer 30. For example... Figure 2 As shown, the width of the groove 25 can also narrow from the side of the second resin layer 20 opposite to the side of the first resin layer 10 toward the side of the first resin layer 10, and the width of the groove 25 can also be substantially constant in the depth direction.

[0063] The width and depth of the trench 25 are typically substantially the same as the width and thickness of the conductive layer 30, respectively. In this specification, the width of the trench 25 refers to its maximum width in the direction perpendicular to the thickness direction of the conductive film 100 (the extension direction of the conductive film 100), and the depth of the trench 25 refers to its maximum depth in the thickness direction of the conductive film 100. The ratio of the depth to the width of the trench 25 can also be the same as the aspect ratio of the conductive layer 30 described above.

[0064] The thickness of the second resin layer 20 or the thickness of the second resin portion 22 can be, for example, 1 μm or more, 1.5 μm or more, or 2 μm or more, or it can be 5 μm or less, 4 μm or less, or 3 μm or less.

[0065] Figures 4-6 It is a schematic representation of manufacturing. Figure 1 A cross-sectional view of an example of the method for the conductive film 100 shown. In the method of this embodiment, firstly, as... Figure 4 As shown in (a), a first resin layer 10 comprising first inorganic particles 11 is formed on a surface 1S of a film-like substrate 1. The first resin layer 10 is formed, for example, by a method comprising the steps of applying a coating liquid comprising a resin component forming a first resin portion 12, the first inorganic particles 11, and a solvent onto the substrate 1; and the steps of removing the solvent from the coating film on the substrate 1. Figure 4 The process of (a) can also be a process of preparing a laminate having a substrate 1 and a first resin layer 10 formed on the substrate 1.

[0066] like Figure 4 As shown in (b), a layer 40 containing second inorganic particles is formed on the surface 10S of the first resin layer 10 opposite to the substrate 1. The layer 40 containing second inorganic particles is a layer containing second inorganic particles 21 and a third resin portion 41. The third resin portion 41 may also contain the same material as the second resin portion 22. Figure 4 The process of (b) can also be a process of preparing a laminate having a substrate 1, a first resin layer 10, and a layer 40 containing second inorganic particles in sequence.

[0067] like Figure 4 As shown in (c), the first inorganic particles 11 are exposed from the surface 10S of the first resin layer 10. As a method for exposing the first inorganic particles 11 from the surface 10S, for example, the following can be described: Figure 4 (b) A method for ashing the laminate to remove a portion of the third resin portion 41 in the layer 40 containing the second inorganic particles and a portion of the first resin portion 12 in the first resin layer 10. Through the ashing treatment, the first resin layer 10 becomes more compact than... Figure 4(b) is thin at that moment. Through ashing, a portion of the first resin portion 12 is removed, but the first inorganic particles 11 present in the first resin portion 12 remain on the side of the first resin layer 10 opposite to the substrate 1. Therefore, a first resin layer 10 can be formed where the first inorganic particles 11 are biased towards the side opposite to the substrate 1. The third resin portion 41 in the layer 40 containing the second inorganic particles can be completely removed through ashing, or a portion can remain on the surface 10S of the first resin layer 10. By removing the third resin portion 41 in the layer 40 containing the second inorganic particles, the second inorganic particles 21 in the layer 40 containing the second inorganic particles accumulate on the surface 10S of the first resin layer 10. The accumulated second inorganic particles 21 can also adhere to the first resin portion 12 or the exposed first inorganic particles 11a. Figure 4 The process (c) can also be a process of removing a portion of the first resin portion 12 in the first resin layer 10 and the third resin portion 41 in the layer 40 containing the second inorganic particles, so that a plurality of first inorganic particles 11 are exposed on the surface 10S of the first resin layer 10.

[0068] like Figure 4 As shown in (d), a second resin layer 20 is formed on the surface 10S of the first resin layer 10. Specifically, a second resin layer 20 containing the second resin portion 22 and the second inorganic particles 21 is formed by applying a resin composition containing the resin component that forms the second resin portion 22 onto the surface 10S of the first resin layer 10 where the second inorganic particles 21 are deposited. Here, if a portion of the third resin portion 41 in the layer 40 containing the second inorganic particles remains on the surface 10S of the first resin layer 10, the remaining third resin portion 41 becomes part of the second resin portion 22 of the second resin layer 20. Figure 4 The process (d) can also be a process of preparing a laminate having a substrate 1, a first resin layer 10, and a second resin layer 20 in sequence.

[0069] like Figure 5 As shown in (a) and (b), a groove (groove) 25 is formed in the second resin layer 20 by using an imprinting method with a mold 50 having a protrusion 50a. In this process, the mold 50, having a protrusion 50a of a predetermined shape, is moved in the direction indicated by arrow A, causing the mold 50 to be pressed into the second resin layer 20. Figure 5 (a)). It can also be pressed into the mold 50 until the tip of the protrusion 50a reaches the first resin layer 10. In this state, the second resin portion 22 is cured as needed. If the second resin portion 22 before curing contains a light-curable resin, the second resin portion 22 is cured by irradiating it with light such as ultraviolet light. Afterwards, by removing the mold 50, a groove 25 is formed having a shape that reverses the shape of the protrusion 50a of the mold 50. Figure 5(b) The method for forming the trench 25 is not limited to imprinting; for example, the trench 25 can also be formed by laser, dry etching, or photolithography. The trench 25 extends on the first resin layer 10 in a manner that forms a pattern corresponding to the conductive layer 30. In order to expose the second inorganic particles 21 on the bottom surface of the trench 25, the second resin portion 22 remaining on the first resin layer 10 in the trench 25 can also be removed by etching such as dry etching after the mold 50 is removed. Figure 5 The processes (a) and (b) can also be processes in which a groove 25 is formed on the surface of the second resin layer 20 opposite to the first resin layer 10 in a laminate having a substrate 1, a first resin layer 10 and a second resin layer 20 in sequence.

[0070] The mold 50 can also be formed from quartz, Ni, UV-curable liquid silicone rubber (PDMS), etc. The shape of the protrusion 50a of the mold 50 is designed according to the shape of the groove 25 to be formed.

[0071] like Figure 5 As shown in (c), a conductive layer 30 is formed to fill the trench 25. By forming the conductive layer 30 to fill the trench 25, a conductive film 100 can be obtained. The method for forming the conductive layer 30 is, for example, as shown in [example missing]. Figure 6 As shown in (a) to (c).

[0072] First, such as Figure 6 As shown in (a), a first metal layer 30a is formed at the bottom of the groove 25 of the laminate in which the groove 25 is formed. The first metal layer 30a can be formed by immersing the laminate in which the groove 25 is formed in a first chemical plating solution containing ions of the metal constituting the first metal layer 30a. Figure 6 The process of (a) can also be a process of preparing a laminate that sequentially comprises a substrate 1, a first resin layer 10, a second resin layer 20 having a groove 25 formed on a surface opposite to the first resin layer 10, and a first metal layer 30a formed in the groove 25.

[0073] The first chemical plating solution contains ions of the metal that constitutes the first metal layer 30a. The first chemical plating solution may also contain phosphorus, boron, iron, etc.

[0074] The temperature of the first chemical plating solution, in which the laminate is immersed, can be, for example, 40 to 80°C. The immersion time in the first chemical plating solution varies depending on the thickness of the first metal layer 30a, and can be, for example, 1 to 10 minutes.

[0075] like Figure 6As shown in (b), a third metal layer 30c is formed on the first metal layer 30a. The third metal layer 30c can be formed by immersing the laminate on which the first metal layer 30a is formed in an aqueous solution containing the metal constituting the third metal layer 30c. Figure 6 The process of (b) may also be a process of preparing a laminate comprising, in sequence, a substrate 1, a first resin layer 10, a second resin layer 20 having a groove 25 formed on a surface opposite to the first resin layer 10, a first metal layer 30a formed in the groove 25, and a third metal layer 30c formed on the first metal layer 30a.

[0076] The aqueous solution contains the metal constituting the third metal layer 30c. The temperature of the aqueous solution when immersing the laminate can be, for example, 20–60°C. The immersion time of the aqueous solution varies depending on the thickness of the third metal layer 30c, and can be, for example, 1–10 minutes.

[0077] like Figure 6 As shown in (c), a second metal layer 30b is formed on the third metal layer 30c. The second metal layer 30b can be formed by immersing the laminate on which the third metal layer 30c is formed in a second chemical plating solution containing ions of the metal constituting the second metal layer 30b. Figure 6 Step (c) can also be a step of preparing a laminate comprising, in sequence, a substrate 1, a first resin layer 10, a second resin layer 20 having a trench 25 formed on a surface opposite to the first resin layer 10, a first metal layer 30a formed in the trench 25, a third metal layer 30c formed on the first metal layer 30a, and a second metal layer 30b formed on the third metal layer 30c. If the conductive layer 30 does not have a third metal layer 30c, the laminate having the first metal layer 30a can be immersed in a second chemical plating solution containing ions of the metal constituting the second metal layer 30b, thereby forming the second metal layer 30b on the first metal layer 30a.

[0078] The second electroless plating solution contains ions of the metal that constitutes the second metal layer 30b. The second electroless plating solution may also contain formalin, etc.

[0079] The temperature of the second chemical plating solution when immersing the laminate in it can be, for example, 30–60°C. The immersion time in the second chemical plating solution varies depending on the thickness of the second metal layer 30b, and can be, for example, 2–20 minutes.

[0080] The conductive film illustrated above can be incorporated into a display device as, for example, a planar transparent antenna. The display device may also be, for example, a liquid crystal display or an organic EL display. Figure 7 This is a cross-sectional view showing one embodiment of a display device in which a conductive film 100 is incorporated. Figure 7 The display device 500 shown includes an image display unit 60 having an image display area 60S, a conductive film 100, a polarizer 70, and a cover glass 80. The conductive film 100, the polarizer 70, and the cover glass 80 are sequentially stacked on the image display area 60S side of the image display unit 60, starting from the image display unit 60 side.

[0081] The structure of the display device is not limited to Figure 7 The form of the polarizer can be changed appropriately as needed. For example, the polarizer 70 can also be disposed between the image display unit 60 and the conductive film 100. The image display unit 60 can also be, for example, a liquid crystal display unit. As the polarizer 70 and the cover glass 80, polarizers and cover glasses commonly used in display devices can be used. The polarizer 70 and the cover glass 80 may also be unnecessary.

[0082] Display devices are an example of applications for conductive films, but conductive films can also be used in devices other than display devices. For example, conductive films can also be used as transparent antennas in the glass of buildings or automobiles.

[0083] The technology disclosed herein includes the following configuration examples, but is not limited thereto.

[0084] One aspect of the present disclosure relates to a conductive film having a film-shaped substrate and a conductive layer disposed on a main surface side of the substrate. The conductive layer has a first metal layer containing a first metal and a second metal layer containing a second metal different from the first metal, which are disposed sequentially from the substrate side. The first metal layer includes grain boundaries.

[0085] According to the above-mentioned conductive film, the first metal layer contains grain boundaries, the surface area of ​​the first metal layer is increased, and the adhesion between the first metal layer and other metal layers is improved.

[0086] In the aforementioned conductive film, a second metal may also be present at the grain boundaries. This increases the conductivity of the conductive layer, and simultaneously, through the anchoring effect of the second metal present at the grain boundaries, further improves the adhesion between the first metal layer and other metal layers.

[0087] In the aforementioned conductive film, the conductive layer may also include a third metal layer, which is disposed between the first and second metal layers and contains a third metal different from the first and second metals. Accordingly, by multiplying the conductive layer, the stress applied to the conductive film is dispersed, further improving the adhesion between the first and third metal layers and between the second and third metal layers.

[0088] In the aforementioned conductive film, a third metal may also be present at the grain boundaries. Accordingly, the anchoring effect of the third metal present at the grain boundaries further enhances the adhesion between the first and third metal layers.

[0089] In the aforementioned conductive film, the conductivity of the second metal, the conductivity of the first metal, and the conductivity of the third metal can increase sequentially. Therefore, the conductive film easily possesses excellent conductivity.

[0090] In the aforementioned conductive film, the third metal layer may also have a thickness smaller than either the thickness of the first metal layer or the thickness of the second metal layer. Accordingly, the conductive film readily exhibits superior adhesion and conductivity between the metal layers.

[0091] The conductive film described above may also include a resin layer disposed between the substrate and the conductive layer, and containing a plurality of inorganic particles. This further improves the adhesion between the conductive layer and the substrate.

[0092] In the aforementioned conductive film, a portion of the plurality of inorganic particles may protrude partially from the resin portion, such that they are partially surrounded by the first metal. Alternatively, a portion of the plurality of inorganic particles may separate from the resin portion and be surrounded by the first metal within the first metal layer. This further improves the adhesion between the conductive layer and the resin layer.

[0093] In the aforementioned conductive film, the conductive layer may also have a pattern including linear portions. Accordingly, the conductive film readily exhibits excellent transparency.

[0094] Furthermore, the display device involved in one aspect of this disclosure includes the aforementioned conductive film.

[0095] Based on the above display device, a display device with a conductive film having high adhesion between metal layers has been obtained.

[0096] This disclosure includes, for example, the following [1] to

[12] .

[0097] [1] A conductive film, wherein the conductive film comprises a film-shaped substrate and a conductive layer disposed on a main surface side of the substrate.

[0098] The conductive layer has a first metal layer containing a first metal and a second metal layer containing a second metal different from the first metal, which are sequentially disposed from the substrate side.

[0099] The first metal layer contains grain boundaries.

[0100] [2] According to the conductive film described in [1], the second metal is also present at the grain boundary.

[0101] [3] According to the conductive film of [1], the conductive layer further comprises a third metal layer disposed between the first metal layer and the second metal layer, and contains a third metal different from the first metal and the second metal.

[0102] [4] According to the conductive film described in [3], the third metal is also present at the grain boundary.

[0103] [5] According to the conductive film of [2], the conductive layer further comprises a third metal layer disposed between the first metal layer and the second metal layer, and contains a third metal different from the first metal and the second metal.

[0104] [6] According to the conductive film described in [5], the third metal is also present at the grain boundary.

[0105] [7] The conductive film according to any one of [3] to [6], wherein the conductivity of the second metal, the conductivity of the first metal, and the conductivity of the third metal increase sequentially.

[0106] [8] The conductive film according to any one of [3] to [7], wherein the third metal layer has a thickness smaller than either the thickness of the first metal layer or the thickness of the second metal layer.

[0107] [9] The conductive film according to any one of [1] to [8], wherein the conductive film further comprises a resin layer disposed between the substrate and the conductive layer, and includes a resin portion and a plurality of inorganic particles.

[0108]

[10] According to the conductive film of [9], a portion of the plurality of inorganic particles protrudes partially from the resin portion in such a manner as to be partially surrounded by the first metal, and / or a portion of the plurality of inorganic particles is separated from the resin portion and surrounded by the first metal within the first metal layer.

[0109]

[11] The conductive film according to any one of [1] to

[10] , wherein the conductive layer has a pattern including linear portions.

[0110]

[12] A display device comprising the conductive film described in

[11] .

[0111] Example

[0112] This disclosure is not limited to the following embodiments.

[0113] [Example 1]

[0114] A coating solution containing silica particles (average particle size 100 nm), acrylic resin, and solvent for forming a first resin layer is prepared. This coating solution is applied to a COP film (100 μm thick), and the solvent is removed from the coating on the COP film in a hot air drying oven. Next, the coating is cured by irradiating it with ultraviolet light using a UV treatment device, forming a first resin layer with a thickness of 300 μm on the COP film, comprising the first resin portion and silica particles (first inorganic particles).

[0115] A coating solution containing Pd microparticles (average particle size 5 nm), acrylic resin, and solvent for forming a layer containing second inorganic particles was prepared. This coating solution was applied onto a first resin layer, and the solvent was removed from the coating film on the first resin layer in a hot air drying oven. Next, the coating film was irradiated with ultraviolet light using a UV treatment device to cure it, forming a 60 μm thick layer containing Pd microparticles (second inorganic particles) on the first resin layer, thus obtaining a laminate.

[0116] The laminate containing the second inorganic particles was placed in a vacuum apparatus and subjected to ashing treatment on the surface of the layer containing the second inorganic particles to remove the resin portion in the layer containing the second inorganic particles and the resin portion on the surface of the first resin layer. The thickness of the first resin layer after ashing treatment was 260 μm.

[0117] A UV-curable resin is coated onto the surface of the first resin layer after ashing treatment to form a coating film with a thickness of 2 μm. Next, a mold with protrusions is pressed into the coating film such that the front end of the mold's protrusion reaches the surface of the first resin layer. The coating film is then irradiated with ultraviolet light to cure it. By removing the mold from the cured coating film, a second resin layer is formed. This second resin layer contains intersecting linear grooves with openings on the surface opposite to that of the first resin layer, forming a mesh-like pattern.

[0118] The laminate after the formation of the second resin layer is placed in a vacuum device for ashing treatment to remove the resin that constitutes the second resin layer remaining at the bottom of the trench.

[0119] Next, the laminate is immersed in a chemical plating solution containing nickel sulfate and sodium hypophosphite, so that the Ni plating layer grows from the surface of the first resin layer and forms a Ni layer (first metal layer) in the trench.

[0120] A laminate containing a Ni layer is immersed in an aqueous solution containing Pd. Next, the resulting laminate is immersed in a chemical plating solution containing copper sulfate and formalin, allowing a Cu plating layer to grow on the Ni layer, starting from the Pd layer, forming a Cu layer (second metal layer) within the trench. Thus, a conductive layer with a mesh pattern of Ni, Pd, and Cu layers is formed within the trench, resulting in a conductive film. The thicknesses of the Ni, Pd, and Cu layers are 100 nm, 30 nm, and 2 μm, respectively.

[0121] To observe the cross-section of the obtained conductive film along its thickness direction, the portion of the conductive film containing the conductive layer was sliced ​​into plates using FIB (Focused Ion Beam) technology, resulting in a thin-film sample for TEM observation. The prepared sample was observed in bright-field mode using a TEM (JEM-2011F) at an accelerating voltage of 200 kV, confirming the formation of grain boundaries within the Ni layer. EDS-STEM analysis confirmed the presence of some silica particles from the first resin layer within the Ni layer, and also confirmed the presence of Pd and Cu at the grain boundaries of the Ni layer.

[0122] [Example 2]

[0123] Except that no ashing treatment was performed after the formation of the second resin layer and before the formation of the first metal layer, the conductive film was fabricated using the same method as in Example 1. TEM observation of the cross-section of the obtained conductive film along its thickness direction confirmed the formation of grain boundaries within the Ni layer. Furthermore, EDS-STEM analysis confirmed the presence of silica particles surrounded by Ni within the Ni layer, and also confirmed the presence of Pd and Cu at the grain boundaries of the Ni layer.

[0124] [Example 3]

[0125] Except that no ashing treatment was performed after the formation of the layer containing the second inorganic particles and before the formation of the second resin layer, the conductive film was fabricated using the same method as in Example 1. TEM observation of the cross-section of the obtained conductive film along its thickness direction confirmed the formation of grain boundaries within the Ni layer. Furthermore, EDS-STEM analysis confirmed the presence of silica particles surrounded by Ni within the Ni layer, and also confirmed the presence of Pd and Cu at the grain boundaries of the Ni layer.

[0126] [Comparative Example 1]

[0127] Except that no ashing treatment was performed after the formation of the layer containing the second inorganic particles and before the formation of the second resin layer, and no ashing treatment was performed after the formation of the second resin layer and before the formation of the first metal layer, the conductive film was fabricated using the same method as in Example 1. TEM observation of the cross-section of the obtained conductive film in the thickness direction revealed that no multiple grain boundaries were identified in the Ni layer.

[0128] <Evaluation of Fit>

[0129] Adhesion was evaluated using a cross-section test as specified in JIS K 5600. Specifically, a right-angled grid pattern (25 squares) was formed by making cuts on the surface of the area containing the second resin layer and the conductive layer using a cutting tool. Adhesive tape was then applied to the grid pattern, ensuring adhesion between the second resin layer, the conductive layer, and the tape. The tape was then peeled off. The grid pattern after tape removal was observed using an optical microscope. Cases where no conductive layer peeling was detected were rated as A, and cases where conductive layer peeling was detected were rated as B. The results are shown in Table 1. In each embodiment, interlayer peeling in the conductive layer was not detected.

[0130] [Table 1]

[0131]

[0132] Explanation of symbols:

[0133] 1…substrate, 10…first resin layer, 11, 11a, 11b…first inorganic particles, 12…first resin portion, 20…second resin layer, 21…second inorganic particles, 22…second resin portion, 25…groove, 30…conductive layer, 30a…first metal layer, 30b…second metal layer, 30c…third metal layer, 31…grain boundary, 40…layer containing second inorganic particles, 41…third resin portion, 50…mold, 60…image display portion, 70…polarizer, 80…cover glass, 100…conductive film, 500…display device.

Claims

1. A conductive film, wherein, The conductive film comprises a film-shaped substrate and a conductive layer disposed on one main surface side of the substrate. The conductive layer has a first metal layer containing a first metal and a second metal layer containing a second metal different from the first metal, which are sequentially disposed from the substrate side. The first metal layer contains grain boundaries. The conductive film further comprises a resin layer disposed between the substrate and the conductive layer, and includes a resin portion and a plurality of inorganic particles. A portion of the plurality of inorganic particles protrudes partially from the resin portion in such a manner that it is partially surrounded by the first metal, and a portion of the plurality of inorganic particles is separated from the resin portion and is surrounded by the first metal within the first metal layer.

2. The conductive film according to claim 1, wherein, The second metal is also present at the grain boundary.

3. The conductive film according to claim 1, wherein, The conductive layer further comprises a third metal layer disposed between the first metal layer and the second metal layer, and containing a third metal different from the first metal and the second metal.

4. The conductive film according to claim 3, wherein, The third metal is also present at the grain boundary.

5. The conductive film according to claim 2, wherein, The conductive layer further comprises a third metal layer disposed between the first metal layer and the second metal layer, and containing a third metal different from the first metal and the second metal.

6. The conductive film according to claim 5, wherein, The third metal is also present at the grain boundary.

7. The conductive film according to any one of claims 3 to 6, wherein, The electrical conductivity of the second metal, the electrical conductivity of the first metal, and the electrical conductivity of the third metal increase sequentially.

8. The conductive film according to any one of claims 3 to 6, wherein, The third metal layer has a thickness smaller than either the thickness of the first metal layer or the thickness of the second metal layer.

9. The conductive film according to any one of claims 1 to 6, wherein, The conductive layer has a pattern including linear portions.

10. A display device, wherein, It possesses the conductive film as described in claim 9.

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