Silver migration resistant conductive film coating and preparation method thereof

Abstract

The invention discloses an anti-silver-migration conducting film which comprises a silver paste conducting layer, a second waterproof layer, a metal conducting layer, a base film, a first waterproof layer and a surface coating which are sequentially arranged from top to bottom. And the second waterproof layer comprises the following components in parts by weight: 50-70 parts of acrylic resin, 10-20 parts of a monomer, 4-8 parts of a photoinitiator and 2-6 parts of a silane coupling agent. In the second waterproof layer, the acrylic resin is any one or a mixture of several of UV type acrylic resin, polyurethane acrylic resin, modified epoxy acrylic resin and polyester acrylic resin. The PET conductive film has the following beneficial effects that through the synergistic effect of the overall film layer structural design and the coating formula, the finally prepared PET conductive film has the characteristics of a highly compact structure, effective water vapor blocking, insulating and blocking functions, high hardness and good wear resistance.

Description

Technical Field

[0001] This invention relates to the field of conductive film technology, and specifically to an anti-silver migration conductive film and its preparation method. Background Technology

[0002] Conductive films are functional thin films deposited on an insulating substrate using physical or chemical methods, possessing the ability to conduct electric current. Based on different material systems, they can be mainly classified into several categories, including metal conductive films (such as aluminum, silver, and copper), metal oxide conductive films (such as ITO and AZO), and conductive polymer films (such as PEDOT:PSS). Among these, metal conductive films, due to their excellent electrical conductivity, thermal conductivity, and optical reflection properties, have been widely used in flexible circuits, touch sensors, electromagnetic shielding, and other fields.

[0003] However, if the silver-based conductive film is operated under a DC electric field and humid and hot environment for a long period of time, the silver-based conductive film is prone to "silver migration". The specific mechanism is as follows: When ambient water vapor permeates into the membrane, it undergoes electrolysis under the influence of an electric field, producing hydrogen ions and hydroxide ions; silver, acting as the anode, undergoes an oxidation reaction to generate silver ions (Ag). + The silver ions migrate to lower potential regions under the influence of an electric field. As the migration continues, silver ions are reduced and precipitated near the cathode, forming dendritic or flocculent conductive dendrites. These dendrites can cause short circuits between electrodes, decrease insulation resistance, increase signal interference, and even lead to device malfunction.

[0004] CN120299783A discloses an anti-silver migration conductive film and a method for manufacturing the same. The anti-silver migration conductive film includes a moisture-absorbing layer, a silver paste electrode, a superhydrophobic coating, and a protective layer. The silver paste electrode includes a ground wire and several signal lines. The thickness of the silver paste electrode is less than the thickness of the moisture-absorbing layer, and the thickness of the superhydrophobic coating is less than the thickness of the moisture-absorbing layer. On a sensor substrate, a moisture-absorbing layer is disposed between the ground wire and the signal lines, and between the signal lines. A superhydrophobic coating is disposed above the silver paste electrode, and a protective layer is disposed above the superhydrophobic coating. This application solves the problem of silver migration in touchscreens.

[0005] Silver migration is a particularly prominent issue in PET (polyethylene terephthalate) based conductive films. Because PET itself has a certain degree of moisture permeability, under high temperature and high humidity conditions, moisture can more easily penetrate to the silver layer interface, exacerbating the dissolution and migration of silver ions. This leads to decreased product reliability, shortened lifespan, and increased defect rates.

[0006] In summary, there is an urgent need to find a way to suppress silver migration, thereby improving the stability and durability of PET conductive films in harsh environments. Summary of the Invention

[0007] The purpose of this invention is to provide an anti-silver migration conductive film and its preparation method. By combining organic and inorganic layers, the water-blocking performance of the conductive film is improved, effectively solving the problem of silver migration in the conductive film.

[0008] To achieve the above objectives, the following technical solutions are used: An anti-silver migration conductive film includes, from top to bottom, a silver paste conductive layer, a second water-blocking layer, a metal conductive layer, a base film, a first water-blocking layer, and a top coating layer.

[0009] As a further improvement to this solution, the second water-blocking layer comprises the following components by weight fraction: A mixture of 50-70 parts acrylic resin, 10-20 parts monomer, 4-8 parts photoinitiator and 2-6 parts silane coupling agent.

[0010] As a further improvement to this solution, in the second water-blocking layer, The acrylic resin is any one or a mixture of several of the following: UV-type acrylic resin, polyurethane acrylic resin, modified epoxy acrylic resin, and polyester acrylic resin. The monomer is any one or a mixture of several of acrylates and modified acrylates; The photoinitiator is any one or a mixture of several of aromatic ketones, benzoin and their derivatives; The silane coupling agent is one or more of KH-550, KH-560 and KH-570.

[0011] As a further improvement to this solution, the metal conductive layer is made of copper compound, which includes copper oxide, copper nitride and other copper alloys.

[0012] As a further improvement to this solution, the base film is one or more of polyethylene terephthalate, polyimide, polyethylene naphthalate, polycarbonate, and polystyrene.

[0013] As a further improvement to this solution, the first water-blocking layer is one or more oxides of Al, Si, Zr, Ti, Hf, Ta, In, Sn, and Zn.

[0014] As a further improvement to this solution, the surface coating comprises the following components in parts by weight: A mixture of 20-30 parts acrylic resin, 3-5 parts photoinitiator, 70-80 parts solvent, 3-5 parts silane coupling agent and 0.1-0.5 parts leveling agent.

[0015] As a further improvement to this solution, in the topcoat layer, The solvent is any one or a mixture of several of the following: ethyl acetate, butyl acetate, propylene glycol methyl ether, propylene glycol methyl ether acetate, methyl isobutyl ketone, butanone, toluene, xylene, and cyclohexanone. The leveling agent is any one or a mixture of several of the following brands: BYK333, BYK-350, BYK-352, BYK-354, BYK-378, and BYK-UV3500; The acrylic resin is any one or a mixture of several of the following: UV-type acrylic resin, polyurethane acrylic resin, modified epoxy acrylic resin, and polyester acrylic resin. The photoinitiator is any one or a mixture of several of aromatic ketones, benzoin and their derivatives; The silane coupling agent is any one or a mixture of several of KH-550, KH-560 and KH-570.

[0016] As a further improvement to this solution, the thickness of the silver paste conductive layer is 1~5μm; the thickness of the second water-blocking layer is 10~20μm; the thickness of the metal conductive layer is 0.1~30μm; the thickness of the base film is 30~500μm; the thickness of the first water-blocking layer is 5~100μm; and the thickness of the topcoat layer is 3~10μm.

[0017] A method for preparing an anti-silver migration conductive film includes the following preparation steps: The base film is a resin; The aforementioned conductive metal layer is attached to one side of the base film by physical vapor deposition or chemical vapor deposition; The second water-blocking layer is a mixture of acrylic resin, monomer, photoinitiator and silane coupling agent, which is attached to the metal conductive layer by transfer printing. The silver paste conductive layer is a conductive paste with silver as the main component, and silver powder accounts for 70-90% of the total weight of the silver paste. It is attached to the second water-blocking layer through a printing process. The first water-blocking layer is an inorganic oxide, which is attached to the other side of the base film by physical vapor deposition or chemical vapor deposition. The topcoat is a mixture of acrylic resin, photoinitiator, solvent, silane coupling agent and leveling agent, which is applied to the first water-blocking layer by a roller coating process.

[0018] It has the following beneficial effects: This invention improves the water-blocking performance of the conductive film by combining organic and inorganic layers, and solves the problem of silver migration in the conductive film.

[0019] This invention innovatively combines a conductive layer and a water-blocking layer on the same base film, effectively reducing costs while offering advantages such as simple construction process and high efficiency.

[0020] As can be seen from the test results of Examples 1-2 and the comparative examples in this invention, the overall structural design and coating experimental formula of this invention work synergistically to ultimately produce a PET conductive film with a highly dense structure that can effectively block water vapor and play the role of insulation barrier, while also taking into account the characteristics of high hardness and good wear resistance, thus providing more effective protection for the product. Attached Figure Description

[0021] Figure 1 Schematic diagram of each layer of PET conductive film; Figure 2 Microscopic view of the conductive film after double 85 circuitry; Figure 3 Example 1: Microscopic view of the conductive film after dual 85 circuitry; Figure 4 Comparative conductive film after installation (actual image of the 85mm dual-phase conductive film); Figure 5 Example 1: Actual picture of the conductive film after installation (Double 85). Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with embodiments and accompanying drawings: Example 1 An anti-silver migration conductive film is prepared by the following method: In this embodiment, the transparent base film is a 125μm thick transparent PET film; The silver paste used in the silver paste layer is DK61A from Dicotech, which is applied to the surface of the second water-blocking layer by screen printing, with a thickness of 3μm.

[0023] Preparation of the second water-blocking coating Take 70 parts of polyurethane acrylic resin, 24 parts of HDDA monomer, 4 parts of 184 photoinitiator and 2 parts of KH560 silane coupling agent, mix them evenly, and then coat them onto the metal conductive layer by transfer printing. The coating thickness is 10μm.

[0024] The conductive metal layer is copper oxide, which is deposited on the surface of the PET base film by magnetron sputtering, and the thickness of the metal layer is 8nm.

[0025] The first water-blocking layer is made of silicon oxide and is deposited on the other side of the transparent base film by plasma-enhanced chemical vapor deposition, with a thickness of 15nm.

[0026] Topcoat coating preparation The solvent is propylene glycol methyl ether PM (70 parts), hexafunctional polyurethane acrylate resin (10 parts), nonafunctional polyurethane acrylate resin (6 parts), difunctional polyurethane acrylate resin (5 parts), HDDA monomer (3 parts), KH570 silane coupling agent (2 parts), BYK333 leveling agent (0.5 parts), and 184 photoinitiator (3.5 parts). A roller coating process is used to coat the surface of the first water-blocking coating, improving the surface hardness and wear resistance of the conductive film.

[0027] Example 2 An anti-silver migration conductive film is prepared by the following method: In this embodiment, the transparent base film is a 125μm thick transparent PET film; The silver paste used in the silver paste layer is DK61A from Dicotech, which is applied to the surface of the second water-blocking layer by screen printing, with a thickness of 3μm.

[0028] Preparation of the second water-blocking coating Take 65 parts of polyurethane acrylic resin, 30 parts of HDDA monomer, 3 parts of 184 photoinitiator and 2 parts of KH560 silane coupling agent, mix them evenly, and then coat them onto the metal conductive layer by transfer printing. The coating thickness is 10μm.

[0029] The conductive metal layer is copper oxide, which is deposited on the surface of the PET base film by magnetron sputtering, and the thickness of the metal layer is 8nm.

[0030] The first water-blocking layer is made of silicon oxide and is deposited on the other side of the transparent base film by plasma-enhanced chemical vapor deposition, with a thickness of 15nm.

[0031] Topcoat coating preparation The solvent is propylene glycol methyl ether PM (70 parts), hexafunctional polyurethane acrylate resin (9 parts), nonafunctional polyurethane acrylate resin (7 parts), difunctional polyurethane acrylate resin (5 parts), HDDA monomer (3 parts), KH570 silane coupling agent (2 parts), BYK333 leveling agent (0.5 parts), and 184 photoinitiator (3.5 parts). A roller coating process is used to coat the surface of the first water-blocking coating, improving the surface hardness and wear resistance of the conductive film.

[0032] Comparative Example 1 A control conductive film is prepared as follows: The base film is a 125um transparent PET film; The silver paste for the silver paste layer is DK61A from Dike, which is coated onto the surface of the second water-blocking layer by screen printing, with a thickness of 3um. The second water-blocking layer uses a commercially available solvent-free photosensitive adhesive. The model used in this comparative example is JS003, which is coated onto the metal conductive layer through a transfer process.

[0033] The conductive metal layer is copper oxide, which is deposited on the surface of the PET base film by magnetron sputtering and has a thickness of 8 nm. The other layer of the PET base film is left untreated.

[0034] Performance testing Install the conductive film into the machine and age it for 500 hours at 85°C and 85% humidity under power-on conditions. Test whether the function is normal. If the function is normal, it is considered OK; if the function is abnormal, it is considered NG.

[0035] Water vapor transmission rate test method: The infrared moisture translucency meter was used for testing, referring to the standard GB / T 26253-2010 "Determination of water vapor transmission rate of plastic films and sheets by infrared detector method", with a temperature of 25±0.5℃ and a relative humidity of (90±2)%RH.

[0036] The pencil hardness test was performed according to GB / T6739 standard, with a load of 750 g.

[0037] Steel wool is abrasion resistant, #0000 steel wool, load 1000g, area 1 inch (2.54*2.54cm), 500 cycles of friction, observe whether there are obvious changes on the surface.

[0038] Table 1 Coating performance testing As shown in Table 1, the water-blocking performance of the control conductive film is lower than that of the embodiment conductive film, indicating that the embodiment conductive film has better water-blocking performance. After aging with double 85%, the conductive film in the control example showed silver migration, leading to malfunction; the conductive film in the embodiment did not show silver migration and functioned normally. Figure 2 A microscopic image of silver migration after double 85, Figure 3 The image shows a microscopic view of the double 85mm coating of the embodiment. As can be seen from the image, silver migration occurred in the comparative example, but not in the embodiment. The hardness and wear resistance of the embodiment are higher than those of the comparative example, indicating that the anti-silver migration conductive film coating has higher hardness and wear resistance.

[0039] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A conductive film against silver migration, characterized in that, The anti-silver migration conductive film (10) includes a silver paste conductive layer (11), a second water-blocking layer (12), a metal conductive layer (13), a base film (14), a first water-blocking layer (15), and a top coating layer (16) arranged sequentially from top to bottom.

2. The anti-silver migration conductive film according to claim 2, characterized in that, The second water-blocking layer (12) comprises the following components by weight fraction: A mixture of 50-70 parts acrylic resin, 10-20 parts monomer, 4-8 parts photoinitiator and 2-6 parts silane coupling agent.

3. The anti-silver migration conductive film according to claim 3, characterized in that, In the second water-blocking layer (12), The acrylic resin is any one or a mixture of several of the following: UV-type acrylic resin, polyurethane acrylic resin, modified epoxy acrylic resin, and polyester acrylic resin. The monomer is any one or a mixture of several of acrylates and modified acrylates; The photoinitiator is any one or a mixture of several of aromatic ketones, benzoin and their derivatives; The silane coupling agent is one or more of KH-550, KH-560 and KH-570.

4. The anti-silver migration conductive film according to claim 1, characterized in that, The metal conductive layer (13) is made of copper compound, which includes copper oxide, copper nitride and other copper alloys.

5. The anti-silver migration conductive film according to claim 1, characterized in that, The base film (14) is one or more of polyethylene terephthalate, polyimide, polyethylene naphthalate, polycarbonate, and polystyrene.

6. The anti-silver migration conductive film according to claim 1, characterized in that, The first water-blocking layer (15) is one or more oxides of Al, Si, Zr, Ti, Hf, Ta, In, Sn, and Zn.

7. The anti-silver migration conductive film according to claim 1, characterized in that, The surface coating (16) comprises the following components in parts by weight: A mixture of 20-30 parts acrylic resin, 3-5 parts photoinitiator, 70-80 parts solvent, 3-5 parts silane coupling agent and 0.1-0.5 parts leveling agent.

8. The anti-silver migration conductive film according to claim 7, characterized in that, In the topcoat (16), The solvent is any one or a mixture of several of the following: ethyl acetate, butyl acetate, propylene glycol methyl ether, propylene glycol methyl ether acetate, methyl isobutyl ketone, butanone, toluene, xylene, and cyclohexanone. The leveling agent is any one or a mixture of several of the following brands: BYK333, BYK-350, BYK-352, BYK-354, BYK-378, and BYK-UV3500; The acrylic resin is any one or a mixture of several of the following: UV-type acrylic resin, polyurethane acrylic resin, modified epoxy acrylic resin, and polyester acrylic resin. The photoinitiator is any one or a mixture of several of aromatic ketones, benzoin and their derivatives; The silane coupling agent is any one or a mixture of several of KH-550, KH-560 and KH-570.

9. The anti-silver migration conductive film according to claim 1, characterized in that, The thickness of the silver paste conductive layer is 1~5μm; the thickness of the second water-blocking layer is 10~20μm; the thickness of the metal conductive layer is 0.1~30μm; the thickness of the base film is 30~500μm; the thickness of the first water-blocking layer is 5~100μm; and the thickness of the topcoat layer is 3~10μm.

10. A method for preparing the anti-silver migration conductive film according to any one of claims 1 to 9, characterized in that, The preparation steps include the following: The base film (14) is a resin; The metal conductive layer (13) is attached to one side of the base film by physical vapor deposition or chemical vapor deposition; The second water-blocking layer (12) is a mixture of acrylic resin, monomer, photoinitiator and silane coupling agent, which is attached to the metal conductive layer by transfer printing. The silver paste conductive layer (11) is a conductive paste with silver as the main component, and silver powder accounts for 70-90% of the total weight of the silver paste. It is attached to the second water-blocking layer by printing process. The first water-blocking layer (15) is an inorganic oxide, which is attached to the other side of the base film by physical vapor deposition or chemical vapor deposition. The topcoat (16) is a mixture of acrylic resin, photoinitiator, solvent, silane coupling agent and leveling agent, which is applied to the first water-blocking layer by a roller coating process.

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