Conductive film and method for manufacturing the same

Abstract

The embodiment of the present specification provides a preparation method of a conductive film. The method comprises: preparing a nanometer metal wire mesh layer on a substrate layer; and performing chemical copper plating on the nanometer metal wire mesh layer to form a copper plating layer on the nanometer metal wire mesh layer.

Description

Technical Field

[0001] This specification relates to the field of touch technology, and in particular to a conductive film and its preparation method. Background Technology

[0002] With the development of science and technology, touch interaction has become one of the important methods of human-computer interaction, and is widely used in smart homes, smart appliances, healthcare, self-service supermarkets, commercial advertising, smart logistics, smart checkout, industrial control, automotive displays and other fields. As the film structure of touch devices (e.g., touch screens) in touch interaction devices, conductive films are usually required to have superior electrical properties (e.g., conductivity and conductivity stability).

[0003] Therefore, it is necessary to provide a conductive film with superior electrical properties and its preparation method. Summary of the Invention

[0004] One embodiment of this specification provides a method for preparing a conductive film. The method includes: preparing a nanowire mesh layer on a substrate layer; and performing electroless copper plating on the nanowire mesh layer to form a copper plating layer on the nanowire mesh layer.

[0005] In some embodiments, the nanowire mesh layer includes a nanowire layer and a first protective layer; the electroless copper plating on the nanowire mesh layer includes: pretreating the nanowire mesh layer to increase the number of nanowires exposed outside the first protective layer, to obtain a pretreated nanowire mesh layer; and placing the pretreated nanowire mesh layer in a copper plating solution, whereby copper in the copper plating solution is deposited on top of the pretreated nanowire mesh layer under the self-catalytic effect of the exposed nanowires after pretreatment.

[0006] In some embodiments, the nanowires on the nanowire mesh layer serve as the catalyst.

[0007] In some embodiments, before placing the pretreated nanowire mesh layer in the copper plating solution, the pretreated nanowire mesh layer is immersed in a palladium ion solution to undergo a displacement reaction with the exposed nanowires after pretreatment, thereby forming palladium nanoparticles as a catalyst on the pretreated nanowire mesh layer.

[0008] In some embodiments, the palladium ion solution comprises: 0.1 wt%-5 wt% hydrochloric acid, 0.001 wt%-0.2 wt% palladium salt, and 0.01 wt%-0.1 wt% surfactant, with the balance being solvent.

[0009] In some embodiments, the palladium salt includes at least one of palladium chloride, palladium nitrate, palladium acetate, palladium sulfate, and dichlorodiammonium palladium; the surfactant includes at least one of fluorocarbon surfactants and organosilicon surfactants; and the solvent is deionized water.

[0010] In some embodiments, a second protective layer is provided in areas other than a preset area before the nanowire mesh layer is pretreated.

[0011] In some embodiments, the preset region is the outer peripheral region of the nanowire mesh layer, and the preset region extends along the outer edge of the nanowire mesh layer.

[0012] In some embodiments, the temperature of the copper plating solution is in the range of 30 ℃ to 40 ℃, and the time for the chemical copper plating is in the range of 30 s to 300 s.

[0013] One embodiment of this specification also provides a conductive film. The conductive film includes a substrate layer, a nanowire mesh layer, and a copper plating layer, wherein the nanowire mesh layer is disposed between the copper plating layer and the substrate layer, and the nanowire mesh layer and the copper plating layer are electrically conductive.

[0014] In some embodiments, palladium nanoparticles are present between the nanowire mesh layer and the copper plating layer.

[0015] In some embodiments, the linewidth of the conductive film is in the range of 5 μm to 30 μm.

[0016] In some embodiments, the impedance of the conductive film grid pattern channel does not exceed 20kΩ; and / or the lead impedance of the conductive film does not exceed 1kΩ; and / or the transmittance of the conductive film grid pattern channel region is not less than 80% in the range of 80.1%-80.7%; and / or the haze of the conductive film grid pattern channel region does not exceed 3% in the range of 2.8%-3.2%.

[0017] In some embodiments, the copper plating layer is located at least in the outer peripheral region of the nanowire mesh layer.

[0018] One embodiment of this specification also provides a touch device. The touch device includes the aforementioned conductive film. Attached Figure Description

[0019] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0020] Figure 1This is a flowchart illustrating an exemplary method for preparing a conductive film according to some embodiments of this specification.

[0021] Figure 2 This is a top view of an exemplary conductive film shown according to some embodiments of this specification.

[0022] Figure 3 yes Figure 2 AA sectional view.

[0023] Figure 4 This is a microscope image of the lead electrode of film material A.

[0024] Figure 5 This is a microscope image of the lead electrode of film material F.

[0025] Figure 6 This is a microscope image of the conductive layer of film material G.

[0026] Figure 7 This is a microscope image of the conductive layer of film material H.

[0027] In the figure, 200 is the conductive film, 210 is the substrate layer, 220 is the nano-metal wire mesh layer, 221 is the first conductive mesh line, 222 is the cutout space, 230 is the copper plating layer, 231 is the copper mesh line, and 240 is the conductive layer. Detailed Implementation

[0028] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0029] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0030] In some implementations, conductive films can be prepared by electroless copper plating. Electroless copper plating produces conductive films with good conductivity, but the copper plating layer may have minor defects or unevenness, affecting its conductivity stability. In some embodiments, a nanowire mesh conductive film can be prepared by sequentially coating a nanowire layer, a first protective layer, and a positive photoresist layer onto a substrate layer, followed by exposure, development, etching, and demolding. The nanowire mesh conductive film exhibits good conductivity stability and bend resistance, but its conductivity is slightly lower than that of conductive films prepared by electroless copper plating.

[0031] The embodiments in this specification prepare a nanowire mesh layer on a substrate layer as a flexible electrical conduction framework for the conductive film, and perform chemical copper plating on the nanowire mesh layer to form a copper plating layer as a conductivity enhancement layer. This allows the prepared conductive film to simultaneously possess the superior conductivity stability (e.g., bending resistance) of the nanowire mesh conductive film and the high conductivity of the conductive film prepared by chemical copper plating, thereby meeting the application requirements of flexible device products (e.g., foldable screens and wearable electronics).

[0032] Figure 1 This is a flowchart illustrating an exemplary method for preparing a conductive film according to some embodiments of this specification.

[0033] Figure 2 This is a top view of an exemplary conductive film shown according to some embodiments of this specification.

[0034] Figure 3 yes Figure 2 AA sectional view.

[0035] like Figure 1-3 As shown in the figure, one embodiment of this specification provides a method for preparing a conductive film. The method includes the following steps.

[0036] Step 110: Prepare a nano-metal wire mesh layer 220 on the substrate layer 210.

[0037] Substrate layer 210 refers to the layer that carries the conductive layer (e.g., a nanowire mesh layer and a copper plating layer). The substrate layer may include a PET (polyethylene terephthalate) substrate layer or a CPI (colorless polyimide) substrate layer.

[0038] The substrate layer may be made of one or more of the following materials: polyester (e.g., PET), CPI, cycloolefin polymer (COP), polypropylene (PP), polyethylene (PE), tricellulose acetate (TCA), poly(ethylene terephthalateco-1,4-cylclohexylenedimethyleneterephthalate) (PETG), thermoplastic polyurethane (TPU), polyvinyl alcohol (PVA), or polycarbonate (PC).

[0039] In some embodiments, before fabricating the nanowire mesh layer 220 on the substrate layer 210, the fabrication method may further include: modifying the substrate layer 210. The modification treatment may include at least one of antireflective treatment, anti-reflective treatment, hardening treatment, or anti-glare treatment. At least one of the antireflective treatment, anti-reflective treatment, hardening treatment, or anti-glare treatment can be achieved through coating. Antireflective treatment can increase the light transmittance of the substrate layer. Anti-reflective treatment can reduce the reflection of light by the substrate layer, thereby further increasing the light transmittance of the substrate layer. Hardening treatment can increase the hardness of the substrate layer. For example, hardening treatment can make the surface hardness of the substrate layer reach 3H or higher. Anti-glare treatment can make the surface of the substrate layer a matte, diffuse reflective surface, thereby reducing the interference of external light on the human eye.

[0040] The nanowire mesh layer 220 refers to a layer formed of nanowires with conductive mesh lines (which may be referred to as the first conductive mesh line 221). The nanowires (or nanometals) on the nanowire mesh layer 220 can serve as catalysts for electroless copper plating. The nanowires may include at least one of silver nanowires, gold nanowires, copper nanowires, or platinum nanowires. In some embodiments, the nanowires may also include other nanowires that can serve as catalysts for electroless copper plating. Further description of the nanowire mesh layer 220 can be found in this specification. Figure 3 And related explanations.

[0041] In some embodiments, the first conductive grid line 221 is a continuous nanowire. In some embodiments, without affecting the conductive path of the conductive layer (e.g., the nanowire grid layer), the first conductive grid line 221 comprises multiple nanowires that are randomly distributed and overlap each other.

[0042] Fabricating a nanowire mesh layer 220 on a substrate layer 210 may include: roll-to-roll coating a nanowire layer (which may be referred to as a first nanowire layer) onto the substrate layer 210; coating a protective liquid over the first nanowire layer and drying and curing it to form a first protective layer; roll-to-roll coating a positive photoresist layer over the first protective layer; and exposing the photoresist layer with a photomask, performing DES (developing, etching, and stripping) waterline development, etching, and stripping to form a perforated space 222 on the first nanowire layer, thereby obtaining the nanowire mesh layer 220.

[0043] The first nanowire layer refers to a layer formed by coating nanowires. This first nanowire layer is an overlapping network structure of nanowires without gaps. The first nanowire layer covers the substrate layer. The first nanowire layer can be formed by at least one (e.g., two or three) coating process. At least two coating processes can cover defects such as missing, agglomerated, or foreign matter-induced uneven distribution of nanowires in the first nanowire layer, reducing the likelihood of defects or unevenness in subsequent electroless copper plating.

[0044] The first protective layer refers to a layer formed by applying a protective liquid and then drying and curing it (e.g., UV curing). The first protective layer may include a polymer layer. Accordingly, the protective liquid used to prepare the polymer layer coating is a polymer-containing protective liquid. The polymer-containing protective liquid may include, but is not limited to, one or more combinations of aliphatic polyurethane acrylates, aromatic polyurethane acrylates, polyurethane methacrylates, diallyl phthalate, epoxy acrylates, or epoxy methacrylates.

[0045] In some embodiments, the first protective layer does not completely cover the first nanowire layer. Some nanowires in the first nanowire layer are exposed and not covered by the first protective layer. In other embodiments, the first protective layer completely covers the first nanowire layer. The nanowire mesh layer 220 made from this first nanowire layer, which is completely covered by the first protective layer, is also completely covered by the first protective layer and does not have any exposed nanowires. In this case, the nanowire mesh layer 220 without exposed nanowires needs to be pretreated to expose at least some of the nanowires on the nanowire mesh layer 220 outside the first protective layer. For details regarding the pretreatment of the nanowire mesh layer 220, please refer to the relevant description later in this specification.

[0046] The thickness of the positive photoresist layer can be in the range of 1.0 μm to 3.0 μm.

[0047] The cutout 222 is formed by etching (e.g., laser etching or photolithography) the first nanowire layer, or the first nanowire layer and the first protective layer together. If the part to be etched (i.e., the part that forms the cutout after etching) only contains the first nanowire layer (without the first protective layer), then only that part of the first nanowire layer needs to be etched away. If the part to be etched includes both the first nanowire layer and the first protective layer, then both the first nanowire layer and the first protective layer need to be etched away.

[0048] In some embodiments, at least a portion of the nanowires on the nanowire mesh layer 220 (or the first conductive mesh line 221) are exposed and not covered by the first protective layer. In some embodiments, the nanowire mesh layer 220 with exposed nanowires may be pretreated to increase the number of nanowires exposed outside the first protective layer. In some embodiments, the nanowire mesh layer 220 (or the first conductive mesh line 221) is completely covered by the first protective layer. In this case, it is necessary to pretreat the nanowire mesh layer 220 without exposed nanowires to expose at least a portion of the nanowires on the nanowire mesh layer 220 outside the first protective layer.

[0049] For a description of the first conductive grid line 221 and the cutout 222, please refer to other parts of this specification (e.g., Figure 2 , Figure 3 (and related descriptions).

[0050] Step 120: Perform chemical copper plating on the nano-metal wire mesh layer 220 to form a copper plating layer 230 on the nano-metal wire mesh layer 220.

[0051] Chemical copper plating refers to the process of plating Cu in a copper plating solution under the action of a catalyst. 2+ The process involves reducing the copper content to metallic copper and depositing it onto the catalyst surface. The copper plating layer 230 refers to the layer formed by electroless copper plating, where copper from the copper plating solution is deposited onto the nano-metal wire mesh layer 220.

[0052] In some embodiments, the catalyst may include exposed nanowires (e.g., at least one of silver, gold, copper, or platinum) in the nanowire mesh layer 220. That is, the catalyst may include exposed (or not covered by the first protective layer) nanowires in the nanowire mesh layer (i.e., the first conductive mesh line 221). In other embodiments, the catalyst may include other metals located on the nanowire mesh layer 220. For example, the catalyst may include other metals (e.g., palladium) generated upon reaction with the nanowire mesh layer 220. Further details regarding these other metals (e.g., palladium) can be found in the related description below.

[0053] Electroless copper plating on the nanowire mesh layer 220 involves placing the nanowire mesh layer 220 in a copper plating solution for reaction, resulting in a copper plating layer 230 formed on the nanowire mesh layer 220. For details regarding the copper plating solution, please refer to the latter part of this specification.

[0054] In some embodiments, the exposed (or uncovered by the first protective layer) nanowires in the nanowire mesh layer 220 serve as catalysts, and the formed copper plating layer 230 is located on the nanowire mesh layer 220, with the shape of the copper plating layer 230 being the same as that of the nanowire mesh layer 220. Figure 3 As shown, the conductive film 200 includes a substrate layer 210, a nanowire mesh layer 220, and a copper plating layer 230. The nanowire mesh layer 220 is located between the copper plating layer 230 and the substrate layer 210. Electrical conductivity exists between the nanowire mesh layer 220 and the copper plating layer 230. The nanowire mesh layer 220 and the copper plating layer 230 can be referred to as the conductive layer 240. In this case, the copper plating layer 230 can also be referred to as the copper mesh layer. Chemical copper plating is an autocatalytic deposition process, therefore deposits on both the surface and sidewalls of the nanowires, resulting in a copper mesh layer with a linewidth slightly wider than the nanowire mesh layer 220. For further details regarding the specific structure of the conductive film 200, the linewidth of the copper mesh layer, the linewidth of the nanowire mesh layer 220, and the linewidth of the conductive layer, please refer to other parts of this specification (e.g., Figure 2 , Figure 3 (and related descriptions).

[0055] In some embodiments, when other metal nanoparticles (e.g., palladium) located on the nanowire mesh layer 220 serve as catalysts, the formed copper plating layer 230 is located on the other metal nanoparticles (e.g., palladium). In this case, the other metal nanoparticles (e.g., palladium) are located between the nanowire mesh layer 220 and the copper plating layer 230.

[0056] This specification describes an embodiment that fabricates a nanowire mesh layer on a substrate layer as a flexible electrical conduction framework for a conductive film. A copper plating layer is then chemically plated onto this mesh layer to form a copper plating layer, serving as a conductivity enhancement layer. This allows the resulting conductive film to possess both the superior conductivity stability (e.g., bend resistance) of a nanowire mesh conductive film and the high conductivity of a chemically plated copper film, thus meeting the application requirements of flexible devices (e.g., foldable screens and wearable electronics). Furthermore, chemically plating copper above the nanowire leads reduces the electrode impedance by orders of magnitude, enabling a further reduction in lead width and better meeting the narrow bezel design requirements of touch devices.

[0057] The following provides a more detailed explanation of step 120.

[0058] As mentioned earlier, when the first protective layer does not completely cover the nanowire mesh layer, the exposed nanowires (i.e., not covered by the first protective layer) on the nanowire mesh layer can serve as catalysts for electroless copper plating. In some embodiments, the nanowire mesh layer not completely covered by the first protective layer can be pretreated to increase the number of nanowires exposed outside the first protective layer, further making the resulting copper plating layer more uniform and improving the conductivity of the conductive film. In other embodiments, when the first protective layer completely covers the nanowire mesh layer, the nanowire mesh layer needs to be pretreated to expose at least a portion of the nanowires outside the first protective layer, serving as catalysts for electroless copper plating.

[0059] In some embodiments, electroless copper plating on a nanowire mesh layer includes: pretreating the nanowire mesh layer to increase the number of nanowires exposed outside the first protective layer (e.g., exposing at least a portion of the nanowires in a nanowire mesh layer completely covered by the first protective layer, or increasing the number of nanowires exposed in a nanowire mesh layer not completely covered by the first protective layer), to obtain a pretreated nanowire mesh layer; and placing the pretreated nanowire mesh layer in a copper plating solution, whereby copper in the copper plating solution is deposited on top of the pretreated nanowire mesh layer under the action of a catalyst on the pretreated nanowire mesh layer (e.g., nanowires on the nanowire mesh layer and / or other nanometals (e.g., palladium) generated after reacting with the nanowire mesh layer).

[0060] The nanowire mesh layer may include a nanowire layer (which may be referred to as the second nanowire layer) and a first protective layer. The second nanowire layer is the first nanowire layer after etching, and the second nanowire layer has perforated spaces.

[0061] Pretreatment refers to the process of exposing or increasing the number of exposed nanowires in a nanowire mesh layer. Pretreatment may include plasma treatment, organic solvent immersion, etc., to thin or remove at least part of the first protective layer on the nanowire mesh layer, and further to make the resulting copper plating layer more uniform and improve the conductivity of the conductive film.

[0062] Copper plating solutions may include copper salts (e.g., copper chloride, copper sulfate, or copper nitrate), reducing agents (e.g., formaldehyde or sodium hypophosphite), complexing agents (e.g., EDTA, sodium potassium tartrate, or triethanolamine), pH adjusters (e.g., sodium hydroxide), and stabilizers (e.g., 2,2'-bipyridine or potassium ferrocyanide). Copper plating solutions can be prepared in-house or purchased from the market.

[0063] In some embodiments, the catalyst may comprise nanowires on a nanowire mesh layer, or nanowires exposed outside the first protective layer without pretreatment. In some embodiments, the catalyst may comprise nanowires exposed in a pretreated nanowire mesh layer (e.g., at least one of silver, gold, copper, or platinum). In other embodiments, the catalyst may be other metal nanoparticles located on the nanowire mesh layer 220. For example, the catalyst may comprise other metal nanoparticles (e.g., palladium) generated upon reaction with the nanowire mesh layer 220. Further details regarding these other metals (e.g., palladium) can be found in the related description below.

[0064] The reaction temperature for electroless copper plating can be understood as the temperature of the copper plating solution. To ensure stable electroless copper plating, the temperature of the copper plating solution needs to be set within a preset range. In some embodiments, the temperature of the copper plating solution can be in the range of 30℃-40℃. In some embodiments, the temperature of the copper plating solution can be in the range of 30℃-35℃. In some embodiments, the temperature of the copper plating solution can be in the range of 35℃-40℃. In some embodiments, the temperature of the copper plating solution can be 30℃, 32℃, 34℃, 35℃, 36℃, 38℃, 40℃, etc.

[0065] The electroless copper plating time can be determined based on the desired copper layer thickness, typically ranging from 100nm to 500nm. To balance high conductivity of the copper layer with efficient conductive film preparation, the electroless copper plating time needs to be set within a preset range. In some embodiments, the electroless copper plating time can be in the range of 30s-300s. In some embodiments, the electroless copper plating time is in the range of 50s-250s. In some embodiments, the electroless copper plating time is in the range of 100s-200s. In some embodiments, the electroless copper plating time is in the range of 150s-200s. In some embodiments, the electroless copper plating time is 30s, 60s, 90s, 120s, 150s, 180s, 200s, 230s, 250s, 280s, 300s, etc.

[0066] The embodiments in this specification pretreat the nanowire mesh layer to expose the nanowires in the mesh layer, or increase the number of nanowires exposed outside the first protective layer. The exposed nanowires on the mesh layer are used as catalysts for electroless copper plating. This not only eliminates the need for additional catalysts, simplifying the electroless copper plating process and making the operation simpler, but also improves the preparation efficiency of the conductive film. Furthermore, it makes the resulting copper plating layer more uniform and improves the conductivity of the conductive film.

[0067] In some embodiments, before placing the pretreated nanowire mesh layer in the copper plating solution, the preparation method further includes: immersing the pretreated nanowire mesh layer in a palladium ion solution to allow the exposed nanowires (e.g., at least one of copper or silver) in the pretreated nanowire mesh layer to undergo a displacement reaction with the palladium ion solution, forming metallic palladium nanoparticles on the surface of the exposed nanowires, which can serve as active catalytic sites for subsequent electroless copper plating.

[0068] Palladium nanoparticles can not only act as catalysts to reduce and deposit copper ions, forming a conductive copper layer and improving the conductivity of the grid pattern channels or leads on the conductive film; but also, under the combined effect of microscopic morphology and optical effects, the palladium nanoparticles formed on the surface of metal nanowires exhibit a predominantly gray-black tone on a macroscopic scale, which can reduce the reflection of the metallic color of the copper layer after electroless copper plating to a certain extent and optimize the visual effect.

[0069] In some embodiments, the palladium ion solution comprises: 0.1 wt%-5 wt% hydrochloric acid, 0.001 wt%-0.2 wt% palladium salt, and 0.01 wt%-0.1 wt% surfactant, with the balance being solvent.

[0070] This specification's embodiments omit the colloidal palladium nanoparticle solution used as a catalyst in the preparation of conductive films via electroless copper plating. This is because the colloidal palladium nanoparticle solution requires liquid-phase chemical synthesis, which is not only cumbersome but also results in poor stability of the colloidal palladium nanoparticles, leading to a short shelf life and consequently high production costs for conductive films prepared via electroless copper plating. Instead, this specification's embodiments use a palladium ion solution prepared by dissolving palladium salts in deionized water as a catalyst precursor. Through a displacement reaction with the surface of the nanowires, active catalytic sites for palladium nanoparticles are generated in situ, thereby achieving selective electroless copper plating of the nanowire mesh pattern. The resulting conductive film combines the excellent bending resistance of the nanowire mesh with the high conductivity of the copper mesh; it also simplifies the electroless copper plating process, improves the stability of the palladium-based precursor, and further improves the efficiency and coating quality (such as uniformity and adhesion) of electroless copper plating, ultimately significantly enhancing the conductivity of the mesh channels and leads in the conductive film.

[0071] In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 0.1 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 0.5 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 1 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 2 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 3 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 4 wt%-5 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 1 wt%-4 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 1 wt%-3 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is in the range of 1 wt%-2 wt%. In some embodiments, the mass fraction of hydrochloric acid in the palladium ion solution is 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc.

[0072] In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.001 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.005 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.01 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.05 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.1 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is in the range of 0.15 wt% to 0.2 wt%. In some embodiments, the mass fraction of palladium salt in the palladium ion solution is 0.001 wt%, 0.01 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, etc.

[0073] Palladium salts may include at least one of palladium chloride, palladium nitrate, palladium acetate, palladium sulfate, or dichlorodiammonium palladium.

[0074] In some embodiments, the mass fraction of the surfactant in the palladium ion solution is in the range of 0.01 wt% to 0.1 wt%. In some embodiments, the mass fraction of the surfactant in the palladium ion solution is in the range of 0.03 wt% to 0.1 wt%. In some embodiments, the mass fraction of the surfactant in the palladium ion solution is in the range of 0.05 wt% to 0.1 wt%. In some embodiments, the mass fraction of the surfactant in the palladium ion solution is 0.01 wt%, 0.02 wt%, 0.04 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, etc.

[0075] Surfactants may include at least one of fluorocarbon surfactants and silicone surfactants. Fluorocarbon surfactants may include Capstone® FS-31, Capstone® FS-3100, Capstone® FS-63, etc. Silicone surfactants may include BYK-348, BYK-375, BYK-3450, TEGO-4100, etc.

[0076] The solvent can be deionized water.

[0077] In some embodiments, the pretreated nanowire mesh layer is immersed in palladium ion solution for 30-200 s. In some embodiments, the pretreated nanowire mesh layer is immersed in palladium ion solution for 50-150 s. In some embodiments, the pretreated nanowire mesh layer is immersed in palladium ion solution for 80-100 s. In some embodiments, the pretreated nanowire mesh layer is immersed in palladium ion solution for 30 s, 50 s, 70 s, 100 s, 120 s, 150 s, 180 s, 200 s, etc.

[0078] In some embodiments, before pretreating the nanowire mesh layer, the preparation method further includes: setting a second protective layer in other regions outside the preset region.

[0079] The preset area refers to the area that requires electroless copper plating to improve conductivity. Correspondingly, other areas outside the preset area refer to areas that will not undergo electroless copper plating.

[0080] The second protective layer refers to the insulating layer that protects the nanowires in the nanowire mesh layer from being affected by pretreatment. The second protective layer may include positive photoresist, peelable adhesive, etc.

[0081] Methods for setting a second protective layer may include coating with positive photoresist (to achieve patterning through exposure and development) or coating with peelable adhesive (to achieve patterning directly through screen printing).

[0082] The embodiments in this specification allow for selection of the areas where electroless copper plating is performed. For example, by providing a second protective layer for areas where high conductivity is not required, and thus avoiding electroless copper plating, the optical properties of the resulting conductive film can be improved.

[0083] In some embodiments, the preset region is the outer peripheral region of the nanowire mesh layer, and the preset region extends along the outer edge of the nanowire mesh layer. In some embodiments, the outer peripheral region is the lead region of the touch sensor. Further explanation regarding the outer peripheral region and its outer edge extension can be found in other parts of this specification (e.g., Figure 2 (and related descriptions).

[0084] The outer periphery of the nanowire mesh layer is usually used as the lead area of ​​the touch sensor electrode made of conductive film. In the embodiments of this specification, the outer periphery of the nanowire mesh layer is used as the area for chemical copper plating. After chemical copper plating, the impedance of the lead can be reduced by an order of magnitude, thereby further reducing the line width of the lead and better meeting the design requirements of narrow bezels of touch devices. This solves the problem that traditional conductive films (e.g., conductive films made of ITO (indium tin oxide) or nanosilver wires) are difficult to use to meet the narrow bezel application requirements of touch devices through lead fabrication processes such as screen printing silver paste and laser etching.

[0085] It should be noted that the above description of the method for preparing the conductive film is merely for illustration and explanation, and does not limit the scope of this application. Those skilled in the art can make various modifications and changes to the method for preparing the conductive film under the guidance of this application. However, these modifications and changes are still within the scope of this application.

[0086] One embodiment of this specification also provides a conductive film.

[0087] Figure 2 This is a top view of an exemplary conductive film shown according to some embodiments of this specification.

[0088] Figure 3 yes Figure 2 AA sectional view.

[0089] like Figure 2 and Figure 3 As shown, the conductive film 200 includes a substrate layer 210, a nanowire mesh layer 220, and a copper plating layer 230. The nanowire mesh layer 220 is disposed between the copper plating layer 230 and the substrate layer 210.

[0090] like Figure 3As shown, the nanowire mesh layer 220 includes a conductive mesh structure (which may be referred to as a first conductive mesh structure). The first conductive mesh structure includes first conductive mesh lines 221 and perforated spaces 222.

[0091] The first conductive grid line can be straight (e.g., Figure 2 As shown), curved lines, wavy lines, etc. The shape of the grid formed by the first conductive grid line (which can also be understood as the shape of the cutout) can include polygons (e.g., triangles, rhombuses, squares, etc.). Figure 2 The grid (as shown) is a rectangle, an ellipse, a circle, or an irregular shape. The grid formed by the first conductive grid lines (which can also be understood as a perforated grid) can be arranged in an array or not.

[0092] The linewidth of the nanowire mesh layer 220 refers to the width of the first conductive mesh line (e.g., Figure 3 The linewidth of the nanowire mesh layer is in the range of 5 μm to 30 μm (as shown by "w" in the figure), or the length of the narrower side of the first conductive mesh line. In some embodiments, the linewidth of the nanowire mesh layer is in the range of 5 μm to 25 μm. In some embodiments, the linewidth of the nanowire mesh layer is in the range of 5 μm to 20 μm. In some embodiments, the linewidth of the nanowire mesh layer is in the range of 5 μm to 15 μm. In some embodiments, the linewidth of the nanowire mesh layer is in the range of 5 μm to 10 μm. In some embodiments, the linewidth of the nanowire mesh layer is 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0093] A copper-plated layer obtained by electroless copper plating on a nanowire mesh layer can be called a copper mesh layer. Since the copper mesh layer is prepared using the nanowire mesh layer as a framework, the shape of the copper mesh layer is the same as that of the nanowire mesh layer.

[0094] The copper mesh layer may include a conductive mesh structure (which may be referred to as a second conductive mesh structure). The second conductive mesh structure includes copper mesh lines 231 and perforated spaces 222. The shape and arrangement of the copper mesh lines are the same as those of the first conductive mesh lines. For example, the width of the copper mesh lines is approximately equal to that of the first conductive mesh lines.

[0095] The linewidth of the copper grid layer refers to the width of copper grid line 231 (e.g., Figure 3 (as indicated by "w"), or the length of the narrower side of the copper mesh line 231. In some embodiments, the linewidth of the copper mesh layer is in the range of 5 μm to 30 μm.

[0096] Electrical conductivity exists between the nanowire mesh layer and the copper plating layer, such as... Figure 2 and Figure 3As shown, the nanowire mesh layer 220 and the copper plating layer 230 can be referred to as the conductive layer 240. The shape of the conductive layer is the same as that of the nanowire mesh layer or the copper mesh layer. Figure 2 As shown, the conductive layer 240 may include a conductive mesh structure (which may be referred to as a third conductive mesh structure). The third conductive mesh structure includes second conductive mesh lines and perforated spaces 222. The second conductive mesh lines include first conductive mesh lines and copper mesh lines. The shape and arrangement of the second conductive mesh lines are the same as those of the first conductive mesh lines or copper mesh lines.

[0097] like Figure 2 As shown, the linewidth of conductive layer 240 refers to the width of the second conductive grid line (e.g., Figure 2 or Figure 3 The linewidth of the conductive layer (as shown by "w"), or the length of the narrower side of the second conductive grid line. The linewidth of the conductive layer is approximately equal to that of the copper grid layer or the nanowire grid layer. In the embodiments of this specification, the linewidth of the conductive layer and the linewidth of the conductive film are interchangeable. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 30 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 28 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 25 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 22 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 20 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 18 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 15 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 12 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 10 μm. In some embodiments, the linewidth of the conductive layer is in the range of 5 μm - 8 μm. In some embodiments, the linewidth of the conductive layer is 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0098] The copper plating layer in the embodiments of this specification uses a nano-metal wire mesh layer as a flexible skeleton. In-situ chemical copper plating above the nano-metal wire mesh layer or leads can reduce the channel or lead impedance of the conductive film. While ensuring the conductivity and conductivity stability of the conductive film, it still has better optical performance (e.g., light transmittance) and bending resistance. Furthermore, the touch device made by this method can meet the design requirements of narrow bezels.

[0099] The second conductive grid line (i.e., the first conductive grid line and the copper plating layer (or copper grid line)) can be used to construct the ultra-fine sensing circuit channel of the touch graphic electrode.

[0100] In some embodiments, there are metal nano-palladium particles between the nano-metal wire grid layer and the copper-plated layer. The metal nano-palladium particles, serving as catalysts for generating the copper-plated layer by electroless copper plating, are located between the nano-metal wire grid layer and the copper-plated layer. Moreover, under the combined action of the microscopic morphology and optical effect of the metal nano-palladium particles formed on the surface of the metal nanowires, palladium metal macroscopically exhibits a mainly grayish-black tone, which can reduce the reflection of the copper layer metal color of the layer after electroless copper plating to a certain extent and optimize the visual effect.

[0101] As Figure 2 shown, the outer peripheral region of the nano-metal wire grid layer refers to the outer periphery of the conductive film 100 (such as Figure 2 the region shown by L in the figure). The outer peripheral region of the nano-metal wire grid layer generally serves as the lead region of the touch device prepared with the conductive film.

[0102] The outer peripheral region extending along the outer edge of the nano-metal wire grid layer means that the outer peripheral region is connected to form a whole (such as Figure 2 the "square" shape shown by L in the figure).

[0103] In some embodiments, the copper-plated layer is at least located in the outer peripheral region of the nano-metal wire grid layer. When preparing the touch electrode, there is no need to make electrode leads through the traditional processes of screen printing silver paste and laser etching, and at the same time, it solves the problem that the traditional lead manufacturing process is difficult to meet the application requirements of the narrow side lines of the touch device.

[0104] The grid pattern or channel region of the conductive film may be a conductive layer or a second conductive grid line. The channel impedance of the grid pattern of the conductive film is the resistance when current flows through the touch-sensitive area of ​​the conductive film. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 20 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 18 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 15 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 12 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 10 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 8 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 5 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 3 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 1 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 0.8 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 0.5 kΩ. In some embodiments, the channel impedance of the grid pattern of the conductive film does not exceed 0.2 kΩ. In some embodiments, the grid pattern channel impedance of the conductive film is 0.2 kΩ, 0.3 kΩ, 0.4 kΩ, 0.5 kΩ, 0.6 kΩ, 0.7 kΩ, 0.8 kΩ, 0.9 kΩ, 1 kΩ, 2 kΩ, 3 kΩ, 4 kΩ, 5 kΩ, 6 kΩ, 7 kΩ, 8 kΩ, 9 kΩ, 10 kΩ, 11 kΩ, 12 kΩ, 13 kΩ, 14 kΩ, 15 kΩ, 16 kΩ, 17 kΩ, 18 kΩ, 19 kΩ, 20 kΩ, etc.

[0105] The lead impedance of the conductive film is the resistance of the lead (e.g., connecting wire) from the gold finger contact point to the touch electrode (e.g., a grid pattern) of the conductive film. In some embodiments, the lead impedance of the conductive film does not exceed 1 kΩ. In some embodiments, the lead impedance of the conductive film does not exceed 0.75 kΩ. In some embodiments, the lead impedance of the conductive film does not exceed 0.5 kΩ. In some embodiments, the lead impedance of the conductive film does not exceed 0.3 kΩ. In some embodiments, the lead impedance of the conductive film does not exceed 0.1 kΩ. In some embodiments, the lead impedance of the conductive film is 0.1 kΩ, 0.2 kΩ, 0.4 kΩ, 0.5 kΩ, 0.6 kΩ, 0.75 kΩ, 1 kΩ, etc.

[0106] In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 80%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 82%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 84%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 86%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 88%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is not less than 90%. In some embodiments, the transmittance of the grid pattern channel region of the conductive film is 80%, 83%, 85%, 87%, 90%, etc.

[0107] In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 3%. In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 2.8%. In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 2.5%. In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 2%. In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 1.5%. In some embodiments, the haze of the grid pattern channel region of the conductive film does not exceed 1%. In some embodiments, the haze of the grid pattern channel region of the conductive film is 1%, 1.5%, 1.8%, 2%, 2.5%, 2.8%, 2.9%, 3.0%, etc.

[0108] The conductive films prepared according to the embodiments of this specification exhibit superior conductivity (e.g., electrode channel impedance (also known as mesh pattern channel impedance and lead impedance) compared to simple nanowire mesh conductive films. The conductive films prepared according to the embodiments of this specification also exhibit superior conductivity stability (e.g., flexural strength) compared to those prepared by simple electroless copper plating. Furthermore, the conductive films prepared according to the embodiments of this specification exhibit comparable optical properties (e.g., transmittance) to those prepared by simple electroless copper plating. Finally, the conductive films prepared according to the embodiments of this specification exhibit comparable optical properties (e.g., haze) to those prepared by simple nanowire mesh conductive films.

[0109] In some embodiments, the impedance of the grid pattern channel of the conductive film is not more than 20kΩ, the lead impedance of the conductive film is not more than 1kΩ, the transmittance of the grid pattern channel region of the conductive film is not less than 80%, and the haze of the grid pattern channel region of the conductive film is not more than 3%.

[0110] In some embodiments, the conductive film is prepared by the aforementioned method for preparing a conductive film. This method may include: preparing a nanowire mesh layer on a substrate layer, and performing electroless copper plating on the nanowire mesh layer to form a copper plating layer on the nanowire mesh layer.

[0111] In some embodiments, when there are exposed nanowires on the nanowire mesh layer, the exposed nanowires can serve as catalysts for electroless copper plating. In some embodiments, when there are no exposed nanowires or a small number of exposed nanowires on the nanowire mesh layer, the nanowire mesh layer can be pretreated to expose at least partially the nanowires outside the first protective layer, or to increase the number of exposed nanowires outside the first protective layer, resulting in a pretreated nanowire mesh layer. The exposed nanowires on the pretreated nanowire mesh layer can serve as catalysts for electroless copper plating.

[0112] In some embodiments, a nanowire mesh layer with exposed nanometals or a pretreated nanowire mesh layer is immersed in a palladium ion solution for a preset time to undergo a displacement reaction with the exposed nanowire surface after pretreatment, forming metallic palladium nanoparticles on its surface, which serve as catalytic active sites for subsequent electroless copper plating.

[0113] In some embodiments, a nanowire mesh layer with a catalyst (e.g., a nanowire mesh layer with exposed nanowires and / or a nanowire mesh layer with deposited palladium nanoparticles) is placed in a copper plating solution. Under the action of the catalyst (e.g., nanowires (e.g., at least one of silver nanowires, gold nanowires, copper nanowires, or platinum nanowires) and / or palladium nanoparticles), copper ions in the copper plating solution are reduced and deposited on top of the nanowire mesh layer to form a copper plating layer.

[0114] For descriptions of the preparation methods of the substrate layer, the nanowire mesh layer, the copper plating layer, the copper mesh layer, and the conductive film, please refer to the relevant sections at the beginning of this specification.

[0115] It should be noted that the above description of the conductive film is merely for illustration and not for limiting the scope of this application. Those skilled in the art can make various modifications and changes to the conductive film under the guidance of this application. However, these modifications and changes are still within the scope of this application.

[0116] One embodiment of this specification also provides a touch device. The touch device includes the aforementioned conductive film. The touch device includes a touch electrode. The touch electrode includes the aforementioned conductive film. In some embodiments, the touch electrode may include a touch pattern and leads. The touch pattern may be formed in the area containing the conductive layer and the perforated area of ​​the aforementioned conductive film, and the leads may be formed in the outer peripheral area of ​​the conductive film.

[0117] Since the copper plating layer is located at least in the outer peripheral region of the nano-metal wire mesh layer of the conductive film, the outer peripheral region has high conductivity. Furthermore, when preparing the touch electrode, it is no longer necessary to use the traditional process of screen printing silver paste and laser etching to make leads, thus solving the problem that the traditional lead manufacturing process is difficult to meet the application requirements of narrow edge lines of touch electrodes.

[0118] It should be noted that the above description of the touch electrodes is merely for illustration and explanation, and does not limit the scope of this application. Those skilled in the art can make various modifications and changes to the touch electrodes under the guidance of this application. However, these modifications and changes are still within the scope of this application.

[0119] Example 1 S1. Fabricate touch sensor electrodes (including a silver nanowire mesh layer and silver nanowire lead electrode lines) on a silver nanowire film to obtain film material A. The silver nanowire mesh layer is formed by photolithography of the silver nanowire layer (sheet resistance of 5Ω / □). The mesh shape (or hollow shape) formed by the conductive mesh lines of the silver nanowire mesh layer is rhomboid, with a side length of 220μm and an acute angle of 60°. The linewidth of the silver nanowire mesh layer is 12μm-15μm. The outer periphery of the silver nanowire mesh layer serves as the lead area, with a lead linewidth and spacing of 20μm / 20μm.

[0120] S2. A positive photoresist is coated on top of film material A. After exposure and development by film or chrome plate, the positive photoresist on top of the silver nanowire lead electrode is removed (the silver nanowire mesh layer is still covered by the photoresist), and film material B is obtained.

[0121] S3. Pre-treat membrane material B with plasma to thin the polymer protective layer (also known as the first protective layer) on the silver nanowire lead electrode and increase the number of silver nanowires exposed outside the polymer protective layer to obtain membrane material C.

[0122] S4. Prepare a palladium ion solution (0.1 wt%-5 wt% hydrochloric acid, 0.0085 wt% palladium chloride, and 0.01 wt%-0.1 wt% Capstone® FS-31, with the balance being deionized water). Immerse membrane material C in the palladium ion solution for 30-200 seconds, then remove and dry with hot air. Palladium ions undergo a displacement reaction with the exposed surface of the silver nanowires, forming palladium nanoparticles on the surface of the silver nanowire lead electrodes, thus obtaining membrane material D.

[0123] S5. Place the film material D in a copper plating solution. The temperature of the copper plating solution is in the range of 30 ℃-40 ℃, and the copper plating time is in the range of 30 s-300 s. Perform chemical copper plating. Under the catalytic action of palladium nanoparticles, copper is selectively deposited on the silver nanowire lead electrode line. The copper layer thickness is about 400~500 nm, and the film material E is obtained.

[0124] S6. Immerse membrane material E in a 3%~5% NaOH solution to dissolve the photoresist covering the silver nanowire mesh layer. Wash with deionized water and dry to obtain membrane material F.

[0125] The above-mentioned film material A uses only a layer of silver nanowires as leads, and its microscopic image is as follows. Figure 4 As shown. The leads of film material F consist of a silver nanowire layer and a copper plating layer, as shown in the microscope image. Figure 5 As shown.

[0126] The leads of membrane materials A and F were tested respectively, and the test results are shown in Table 1.

[0127] Table 1 Lead wire test results

[0128] As shown in Table 1, using a silver nanowire layer as the lead frame, an integrated lead composed of silver nanowires and a copper plating layer is prepared by chemical copper plating, which gives it both high conductivity and bending resistance; at the same time, while meeting the conductivity requirements of the lead, the lead design line width can be further reduced.

[0129] Example 2 Based on film material A, copper is electrolessly plated onto the silver nanowire mesh layer to obtain film material G. The difference between the electroless copper plating of this silver nanowire mesh layer and the lead electroless copper plating in Example 1 is that the silver nanowire mesh layer does not react with the palladium ion solution, that is, the catalyst for electroless copper plating is the exposed silver nanowires on the silver nanowire mesh layer.

[0130] Example 3 Based on film material A, copper is electrolessly plated onto the silver nanowire mesh layer to obtain film material H. The electroless copper plating of this silver nanowire mesh layer is the same as that of the leads in Example 1. That is, the catalyst for electroless copper plating is palladium nanoparticles formed on the surface of the silver nanowire mesh layer.

[0131] Example 4 The linewidth of the silver nanowire mesh layer in film material A was adjusted to 5μm~7μm, while other parameters remained basically the same. Copper was then electrolessly plated onto the silver nanowire mesh layer to obtain film material I. The electroless copper plating of this silver nanowire mesh layer was the same as that of the leads in Example 1. That is, the catalyst for the electroless copper plating was palladium nanoparticles formed on the surface of the silver nanowire mesh layer.

[0132] The aforementioned film material A uses only a silver nanowire mesh layer as its conductive layer. Film material G's conductive layer includes both a silver nanowire mesh layer and a copper plating layer, as shown in the microscope image. Figure 6 As shown. By Figure 6 It can be seen that after the copper plating layer is formed by chemical plating on the silver nanowire mesh layer, a distinct copper metallic luster can be observed.

[0133] The conductive layer of film material H includes a silver nanowire mesh layer, a copper plating layer, a blackening layer above the copper layer, and palladium nanoparticles located between the silver nanowire mesh layer and the copper plating layer. A microscopic image of this material is shown below. Figure 7 As shown in Table 2, the conductive layers (which can also be understood as mesh layers or channels) of membrane materials A, G, H, and I were tested respectively. The test results were obtained on a short channel of a 15.6-inch touchscreen pattern, with a channel length of approximately 200 mm. Transmittance and haze were obtained by selecting points using a nine-square grid and calculating the average value. The bending test involved bending the sample at 20°C with a bending radius r = 2.5 mm, with the fixed channel impedance change rate being <10%.

[0134] Table 2 Test results of conductive layer

[0135] Note: The test membrane materials in the table are all based on 50μm thick PET substrates.

[0136] As shown in Table 2, by using a silver nanowire mesh layer as a framework and then performing chemical copper plating on the framework to obtain a conductive layer including the copper plating layer, the channel impedance of the conductive film can be reduced. This allows the channel area of ​​the conductive layer mesh pattern to have both high conductivity and bending resistance, while still maintaining superior optical performance (e.g., light transmittance and haze). Furthermore, while meeting the channel impedance requirements, the design linewidth of the mesh can be further reduced, which is beneficial for further improving the optical performance of the mesh area.

[0137] The beneficial effects that the embodiments of this specification may bring include, but are not limited to: (1) By preparing a nano-metal wire mesh layer on the substrate layer as a flexible conductive skeleton and chemically plating copper on its surface to form a conductive reinforcement layer, the wire width of the conductive layer can be effectively reduced and the channel impedance of the conductive film can be reduced while maintaining excellent optical performance (such as transmittance and haze). The conductive film obtained has both the excellent conductive stability (such as bending resistance) of the nano-metal wire mesh and the high conductivity of chemically plated copper, which can meet the application requirements of flexible devices (such as foldable screens, wearable electronics) and narrow bezel design of touch devices; (2) By pre-treating the nano-metal wire mesh layer, the nano-metal wires in the nano-metal wire mesh layer are exposed, or the nano-metal wires exposed outside the first protective layer are increased, and the exposed nano-metal wires on the nano-metal wire mesh layer are used as catalysts for chemically plated copper. Not only is it unnecessary to introduce additional catalysts, but the chemically plated copper process can be simplified, the operation is simpler, the preparation efficiency of the conductive film can be improved, the copper plating layer can be made more uniform, and the conductivity of the conductive film can be further improved; (3) The pre-treated Immersing the nano-metal wire mesh layer in palladium ion solution can cause the exposed nano-metal (e.g., at least one of copper or silver) in the treated nano-metal wire mesh layer to undergo a displacement reaction with the palladium ion solution, forming metallic palladium nanoparticles on the pretreated nano-metal wire mesh layer. The metallic palladium nanoparticles can not only serve as catalytic active sites for subsequent electroless copper plating, reducing and depositing copper ions to form a conductive copper layer, thus reducing the impedance of the conductive layer of the conductive film and improving the conductivity of the mesh pattern channels or leads on the conductive film; but also, under the combined effect of the micro-morphology and optical effect of the metallic palladium nanoparticles formed on the surface of the metal nanowires, the metallic palladium appears as a gray-black tone on a macroscopic scale, which can reduce the reflection of the metallic color of the copper layer after electroless copper plating to a certain extent and optimize the visual effect; (4) The colloidal palladium nanoparticle catalyst commonly used in traditional electroless copper plating is abandoned, and palladium ion solution prepared by dissolving palladium salt in deionized water is used as the catalyst precursor. Through the displacement reaction with the surface of the nano-metal wire, nano-palladium active catalytic sites are generated in situ, thereby achieving selective electroless copper plating of the nano-metal wire mesh pattern. The resulting conductive film combines the excellent bending resistance of nano-metal mesh with the high conductivity of copper mesh; at the same time, it simplifies the electroless copper plating process, improves the stability of palladium-based precursors, and further improves the efficiency and coating quality (such as uniformity and adhesion) of electroless copper plating, ultimately significantly improving the conductivity of the mesh channels and leads in the conductive film. (5) The embodiments in this specification allow for the selection of areas for electroless copper plating.For example, by setting a second protective layer for areas where high conductivity is not required, and without chemical copper plating, the excellent optical properties of the nanowire mesh layer can be preserved, and the overall light transmittance of the touch electrode channel area can be improved; (6) The area of ​​chemical copper plating includes the outer peripheral area of ​​the nanowire mesh layer and extends along the outer edge of the nanowire mesh layer, so that when the conductive film is subsequently prepared for touch electrode fabrication, it is not necessary to use the traditional process of screen printing silver paste and laser etching to make leads, thus solving the problem that the traditional lead fabrication process is difficult to achieve the application requirements of narrow edge lines of touch electrodes. It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects that may be produced can be any one or a combination of the above, or any other possible beneficial effects.

[0138] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0139] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0140] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0141] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A method for preparing a conductive film, characterized in that, The method includes: Fabrication of a nanowire mesh layer on a substrate layer; and Chemical copper plating is performed on the nano-metal wire mesh layer to form a copper plating layer on the nano-metal wire mesh layer.

2. The method for preparing the conductive film according to claim 1, characterized in that, The nanowire mesh layer includes a nanowire layer and a first protective layer; The process of electroless copper plating on the nanowire mesh layer includes: The nanowire mesh layer is pretreated to increase the number of nanowires exposed outside the first protective layer, resulting in a pretreated nanowire mesh layer. as well as The pretreated nanowire mesh layer is placed in a copper plating solution. Under the action of the catalyst of the exposed nanowires after pretreatment, copper in the copper plating solution is deposited on the pretreated nanowire mesh layer.

3. The method for preparing the conductive film according to claim 2, characterized in that, The nanowires on the nanowire mesh layer serve as the catalyst.

4. The method for preparing the conductive film according to claim 2, characterized in that, Before placing the pretreated nanowire mesh layer into the copper plating solution, the pretreated nanowire mesh layer is immersed in a palladium ion solution to undergo a displacement reaction with the exposed nanowires after pretreatment, thereby forming palladium nanoparticles as a catalyst on the pretreated nanowire mesh layer.

5. The method for preparing the conductive film according to claim 4, characterized in that, The palladium ion solution comprises: 0.1 wt%-5 wt% hydrochloric acid, 0.001 wt%-0.2 wt% palladium salt, and 0.01 wt%-0.1 wt% surfactant, with the balance being solvent.

6. The method for preparing the conductive film according to claim 5, characterized in that, The palladium salt includes at least one of palladium chloride, palladium nitrate, palladium acetate, palladium sulfate, and dichlorodiammonium palladium; The surfactant includes at least one of fluorocarbon surfactants and organosilicon surfactants; and The solvent is deionized water.

7. The method for preparing the conductive film according to claim 2, characterized in that, Before preprocessing the nano-metal wire mesh layer, a second protective layer is set in other areas outside the preset area.

8. The method for preparing the conductive film according to claim 7, characterized in that, The preset region is the outer peripheral region of the nano-metal wire mesh layer, and the preset region extends along the outer edge of the nano-metal wire mesh layer.

9. The method for preparing the conductive film according to claim 2, characterized in that, The temperature of the copper plating solution is in the range of 30 ℃-40 ℃. The electroless copper plating time is in the range of 30 s to 300 s.

10. A conductive film, characterized in that, The conductive film comprises a substrate layer, a nano-metal wire mesh layer, and a copper plating layer, wherein... The nanowire mesh layer is disposed between the copper plating layer and the substrate layer. The nanowire mesh layer and the copper plating layer are electrically conductive.

11. The conductive film according to claim 10, characterized in that, There are palladium nanoparticles between the nano-metal wire mesh layer and the copper plating layer.

12. The conductive film according to claim 10, characterized in that, The linewidth of the conductive film is in the range of 5 μm to 30 μm.

13. The conductive film according to claim 10, characterized in that, The impedance of the grid pattern channel of the conductive film does not exceed 20kΩ; and / or The lead impedance of the conductive film does not exceed 1kΩ; and / or The transmittance of the grid pattern channel region of the conductive film is not less than 80%; and / or the haze of the grid pattern channel region of the conductive film does not exceed 3%.

14. The conductive film according to claim 10, characterized in that, The copper plating layer is located at least in the outer peripheral region of the nanowire mesh layer.

15. A touch device, characterized in that, The touch device includes a conductive film as described in any one of claims 10-14.

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