A full open metal screen with differentiated wear structure and a method of manufacturing the same

Abstract

The application discloses a full-opening metal screen with a differential wear-resistant structure and a manufacturing method thereof, and relates to the technical field of photovoltaic industry. The metal sheet is provided with a plurality of pattern openings, and is provided with a wear-resistant layer facing the surface of a silicon sheet during printing. The wear-resistant layer is provided with an easy-wear layer on the periphery. The wear-resistant performance of the wear-resistant layer is higher than that of the easy-wear layer and the metal sheet. The wear-resistant performance of the easy-wear layer is lower than that of the metal sheet. The application improves the adhesion of the metal screen and the concave-convex silicon sheet, changes the contact form of the peripheral area of the pattern opening of the metal screen and the concave-convex surface of the silicon sheet from point contact to surface contact, and significantly improves the adhesion degree. The abnormal wear and vibration of the metal screen are reduced. After the adhesion is improved, the scraper pressure distribution is more uniform, the vibration amplitude is reduced, the wear rate is reduced, and the service life is prolonged. The long-term stability of the slurry permeability is ensured.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic industry technology, and in particular to a fully open metal mesh with a differentiated wear-resistant structure and its manufacturing method. Background Technology

[0002] Currently, the printing process for photovoltaic cells is gradually shifting from traditional screen printing plates to fully open metal plates. Fully open metal plates are made of nickel or nickel alloys through a deposition process. Compared with traditional screen printing plates, they have higher dimensional accuracy and better wear resistance, and can achieve finer line width grid printing, which helps to improve the photoelectric conversion efficiency of the cells.

[0003] A significant problem was discovered in actual production: to reduce reflectivity, monocrystalline silicon solar cells undergo texturing to create a pyramid-shaped micro-uneven structure on their surface. Simultaneously, the silicon wafers themselves exhibit some degree of surface micro-unevenness after slicing and cleaning processes. The combination of these two factors results in a silicon wafer surface that is essentially an uneven, micro-curved surface. Fully open metal printing plates, using nickel sheets as the substrate, have high hardness but limited ductility. Compared to traditional screen printing plates with better flexibility, metal plates cannot adapt to the unevenness of the silicon wafer surface through localized micro-deformation during printing, resulting in a micro-scale gap between the screen and the wafer. This leads to uneven pressure distribution from the squeegee, causing pressure concentration in localized areas and accelerating wear at the edges of the pattern openings. Furthermore, the unstable adhesion between the screen and wafer during squeegee movement generates additional vibrations, further exacerbating the impact and friction between the screen and the wafer.

[0004] The ultimate consequence of the aforementioned poor bonding problem is unstable paste transmittance. Due to fluctuations in the bonding degree between the screen and the silicon wafer, uneven distribution of squeegee pressure, and accompanying vibration, the transmittance of the paste squeezed out from the pattern opening fluctuates, resulting in unstable wet weight (paste deposition amount) on the solar cell. Fluctuations in wet weight directly affect the aspect ratio and uniformity of the grid lines, ultimately adversely affecting the photoelectric conversion efficiency of the solar cell.

[0005] Currently, the industry's main approach is to adjust printing parameters, such as reducing squeegee pressure, slowing down printing speed, or optimizing silicon wafer texturing processes. However, these methods either sacrifice printing efficiency or are limited by the process window in silicon wafer preparation. They are all passive responses and cannot solve the problem at the structural level, so improvements are urgently needed. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a fully open metal mesh with a differentiated wear-resistant structure and its manufacturing method, in order to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: First aspect: A fully open metal mesh with a differentiated wear-resistant structure includes a metal sheet with multiple patterned openings penetrating the metal sheet. During printing on the metal sheet, a wear-resistant layer is disposed on the silicon wafer surface adjacent to the periphery of the patterned openings. An easy-wear layer is disposed adjacent to the periphery of the wear-resistant layer. The wear resistance of the wear-resistant layer is higher than that of the easy-wear layer and the metal sheet, while the wear resistance of the easy-wear layer is lower than that of the metal sheet.

[0008] Preferably, the wear-resistant layer extends outward from the edge of the pattern opening with a width of 30~80μm.

[0009] Preferably, the metal sheet is made of nickel or a nickel alloy.

[0010] Preferably, the wear-resistant layer is made of a nickel-based alloy plating.

[0011] Preferably, the material of the wear-resistant layer is a material whose wear resistance is significantly lower than that of the wear-resistant layer material, and the material of the wear-resistant layer does not produce harmful pollutants during the wear process.

[0012] Preferably, the materials of the wear-resistant layer and the wear-resistant layer are applied to the metal sheet by electroplating, PVD, or sputtering.

[0013] Preferably, the thickness range of the wear-resistant layer and the wear-resistant layer is 0.1~5μm.

[0014] The second aspect: A method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure includes the following steps: S1. A metal sheet with a patterned opening is produced by using a deposition process combined with dry film exposure and development technology. S2. On the side of the metal sheet facing the silicon wafer, a selective mask is applied. After the dry film is applied, it is exposed and developed to form a patterned mask. The mask covers the patterned opening area and the wear-resistant layer, exposing the wear-prone layer. S3. Deposit a low-wear-resistant material on the exposed wear-prone layer by electroplating, with a deposition thickness of 0.1~5μm; S4, Remove occlusion; S5. Apply selective masking again, apply dry film again, expose, and develop to form a patterned mask. The mask covers the patterned opening area and the easily worn layer, exposing the wear-resistant layer. S6. High wear-resistant material is deposited on the exposed wear-resistant layer by electroplating, with the deposition thickness being consistent with that of the wear-prone layer. S7. Remove the masking to obtain the finished metal mesh plate.

[0015] Preferably, PVD or sputtering can also be used in step S2. If PVD or sputtering is used, a metal mask is used to cover the areas that do not need to be deposited, exposing the wear-prone layer.

[0016] Preferably, PVD or sputtering can also be used in step S5. If PVD or sputtering is used, a metal mask is used to cover the area that does not need to be deposited, exposing the wear-resistant layer.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The bonding problem between the metal mesh and the uneven silicon wafer is improved from a structural perspective. After the wear layer is thinned, the rigidity is reduced, and local concave deformation occurs under the pressure of the scraper. This changes the contact between the area around the opening of the metal mesh pattern and the uneven surface of the silicon wafer from point contact to surface contact, significantly improving the bonding degree.

[0018] 2. It reduces abnormal wear and vibration of the metal screen, and the improved adhesion makes the squeegee pressure distribution more uniform. The vibration amplitude during the printing process is reduced, and the wear rate of the metal screen itself is reduced, thus extending its service life.

[0019] 3. It ensures the long-term stability of slurry permeability. The wear-resistant layer material has good wear resistance, which allows it to remain intact. The geometric dimensions of the pattern openings do not change due to wear. The slurry permeability channels are stable, and the wet weight fluctuation is controlled, which is conducive to improving the photoelectric conversion efficiency of the solar cells.

[0020] 4. It is compatible with existing electroforming and selective masking processes, and can flexibly choose electroplating, PVD or sputtering methods. The manufacturing process relies on existing mature processes, without adding additional complex equipment investment, and the increase in manufacturing costs is limited, making it suitable for large-scale promotion and application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart is shown for a method of manufacturing a fully open metal mesh with a differentiated wear-resistant structure.

[0023] Figure 2 A schematic diagram of a fully open metal mesh with a differentiated wear-resistant structure is shown.

[0024] Figure 3 A top view of a fully open metal mesh with a differentiated wear-resistant structure is shown.

[0025] Figure 4A partial cross-sectional view of the initial state of a fully open metal mesh with a differentiated wear-resistant structure is shown.

[0026] Figure 5 A partial cross-sectional view of the metal mesh after a period of use is shown.

[0027] Figure 6 This diagram shows a cross-sectional view of a metal mesh poorly bonded to the surface of a textured silicon wafer in the prior art.

[0028] Legend: 1. Metal sheet; 2. Graphic opening; 3. Wear-resistant layer; 4. Wear-resistant layer. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] Reference Figures 1 to 6 The present invention provides a further description of an embodiment of a fully open metal mesh with a differentiated wear-resistant structure and its manufacturing method.

[0034] Example 1: A fully open metal screen with a differentiated wear-resistant structure includes a metal sheet 1 made of nickel or a nickel alloy. The metal sheet 1 has multiple patterned openings 2 penetrating it. During printing, a wear-resistant layer 3 is positioned immediately around the patterned openings 2 on the silicon wafer surface. An easily worn layer 4 is positioned immediately around the wear-resistant layer 3. The wear-resistant layer 3 has higher wear resistance than both the easily worn layer 4 and the metal sheet 1. This design ensures the wear-resistant layer 3 remains intact, guaranteeing the stability of the patterned openings 2 and thus consistent ink penetration. The easily worn layer 4 has lower wear resistance than the metal sheet 1. This design causes the material of the easily worn layer 4 to wear down preferentially during printing, reducing its rigidity and creating localized concave deformation under squeegee pressure to improve adhesion to the uneven silicon wafer.

[0035] It should be noted that, depending on the printing conditions and wear characteristics, the wear-prone layer 4 can be set on one side of the battery cell contact surface, or it can be set on both sides of the battery cell contact surface and the doctor blade contact surface, or it can be set only on one side of the doctor blade contact surface.

[0036] The wear-resistant layer 3 extends outward from the edge of the pattern opening 2 with a width of 30~80μm, while the easy-wear layer 4 extends outward from the edge of the wear-resistant layer 3 away from the pattern opening 2 with a width of 80μm. It should be noted that the width of the easy-wear layer 4 can be uneven; for example, a wider easy-wear layer 4 can be provided at the corners of the pattern opening 2, while a narrower easy-wear layer 4 can be provided on straight sections, to achieve differentiated design and thus improve the applicability of the metal mesh.

[0037] The material of wear-resistant layer 3 is a nickel-based alloy coating, such as any one of high-hardness and high-wear-resistant materials such as nickel-phosphorus alloy, nickel-cobalt alloy, chromium, chromium coating, diamond composite coating, diamond-like coating, etc. Since the electroplating process of nickel-cobalt alloy is mature and the cost is controllable, it can be the preferred option.

[0038] The material of the wear-resistant layer 4 is a material whose wear resistance is significantly lower than that of the wear-resistant layer 3, and the material of the wear-resistant layer 4 does not produce harmful pollutants during the wear process. For example, the material of the wear-resistant layer 4 is any one or a combination of tin, copper, and silver. Since the tin plating layer is soft, it can be gradually worn at a controllable speed under the friction of the scraper, and it does not pollute the battery cell printing. Therefore, tin can be the preferred option.

[0039] The materials of wear-resistant layer 3 and wear-resistant layer 4 are applied to metal sheet 1 by electroplating. It should be noted that when there are higher requirements for the purity, density or thickness uniformity of the deposited layer, PVD or sputtering methods are selected.

[0040] The thickness range of wear-resistant layer 3 and wear-resistant layer 4 is 0.1~5μm, and the surface of metal sheet 1 is flat in the initial state.

[0041] Example 2: A method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure includes the following steps: A metal sheet 1 with patterned openings 2 is fabricated using a deposition process combined with dry film exposure and development technology. Specifically, a dry film is laminated onto the metal sheet 1. After exposure and development, the dry film at the location of the patterned openings 2 is removed, exposing the surface of the metal sheet 1 for nickel deposition. The dry film in the remaining areas is retained as a protective layer. After deposition, the dry film is removed to obtain a metal sheet 1 with through-patterned openings 2. Selective masking is applied to the side of the metal sheet 1 facing the silicon wafer. After laminating the dry film, exposure and development are performed to form a patterned mask. The mask covers the area of ​​the patterned openings 2 and the wear-resistant layer 3, exposing the wear-prone layer 4. A low-wear-resistant material is deposited on the exposed wear-prone layer 4 by electroplating, with a deposition thickness of 0.1~5μm. It should be noted that the realization of the wear-resistant layer 4 is not limited to the surface plating of a low-wear-resistant material layer. Alternatively, a void can be reserved at the position of the wear-resistant layer 4 during the electroforming stage, and then a low-wear-resistant material such as soft metals such as tin, copper, silver, and indium, or an organic polymer coating such as polyimide and epoxy resin can be electroplated into the void. It should be noted that the material selection principle for the wear-resistant layer 4 is that the wear resistance is significantly lower than that of the wear-resistant layer 3, and no harmful pollutants are generated during the wear process, forming an inlay structure in which the low-wear-resistant material is embedded in the metal sheet 1. In this structure, the low-wear-resistant material is not easy to peel off during the wear process, but the electroforming process requires high precision control. This method can also achieve the function of preferential wear and thinning of the low-wear-resistant material in the wear-resistant layer 4. The void can penetrate the entire thickness of the metal sheet 1, or it can be set as a blind hole and then filled with low-wear-resistant material to form a shallow inlay structure.

[0042] Then, the dry film mask is removed; selective masking is applied again, dry film is applied again, exposed, and developed to form a patterned mask. The mask covers the pattern opening 2 area and the wear-prone layer 4, exposing the wear-resistant layer 3; a high wear-resistant material is deposited on the exposed wear-resistant layer 3 by electroplating, with the deposition thickness being consistent with the deposition layer of the wear-prone layer 4; the dry film mask is removed to obtain the finished metal mesh.

[0043] Example 3: A method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure includes the following steps: A metal sheet 1 with patterned openings 2 is fabricated using a deposition process combined with dry film exposure and development technology. Specifically, a dry film is laminated onto the metal sheet 1. After exposure and development, the dry film at the locations of the patterned openings 2 is removed, exposing the surface of the metal sheet 1 for nickel deposition. The dry film in the remaining areas is retained as a protective layer. After deposition, the dry film is removed to obtain a metal sheet 1 with through-patterned openings 2. Selective masking is applied to the side of the metal sheet 1 facing the silicon wafer, using a metal mask to cover areas where deposition is not required, exposing a wear-resistant layer 4. A low-wear-resistant material is deposited on the exposed wear-resistant layer 4 using PVD or sputtering, with a deposition thickness of 0.1~5 μm. It should be noted that the realization of the wear-resistant layer 4 is not limited to the surface plating of a low-wear-resistant material layer. Alternatively, a void can be reserved at the position of the wear-resistant layer 4 during the electroforming stage, and then a low-wear-resistant material such as soft metals such as tin, copper, silver, and indium, or an organic polymer coating such as polyimide and epoxy resin can be electroplated into the void. It should be noted that the material selection principle for the wear-resistant layer 4 is that the wear resistance is significantly lower than that of the wear-resistant layer 3, and no harmful pollutants are generated during the wear process, forming an inlay structure in which the low-wear-resistant material is embedded in the metal sheet 1. In this structure, the low-wear-resistant material is not easy to peel off during the wear process, but the electroforming process requires high precision control. This method can also achieve the function of preferential wear and thinning of the low-wear-resistant material in the wear-resistant layer 4. The void can penetrate the entire thickness of the metal sheet 1, or it can be set as a blind hole and then filled with low-wear-resistant material to form a shallow inlay structure.

[0044] Then the metal mask is removed; selective masking is applied again, and the area that does not need to be deposited is covered with the metal mask again, exposing the wear-resistant layer 3; high wear-resistant material is deposited on the exposed wear-resistant layer 3 by PVD or sputtering, and the deposition thickness is consistent with the deposition layer of the wear-prone layer 4; the metal mask is removed to obtain the finished metal mesh.

[0045] The finished metal stencils prepared in Examples 2 and 3, in the initial stage of printing, have a smooth surface, and both the wear-resistant layer 4 and the wear-resistant layer 3 are fully present with consistent thickness and uniform stiffness distribution. At this time, the adhesion between the metal stencil and the uneven surface of the silicon wafer is no different from that in the prior art, but microscopic gaps exist. Figure 4 ; As the number of printing passes increases, the squeegee repeatedly rubs against the screen surface and applies downward pressure. Due to its lower wear resistance, the easily worn layer 4 gradually wears down under this friction, resulting in a thinner coating in this area. Meanwhile, the wear-resistant layer 3, made of highly wear-resistant material, experiences minimal wear, and its thickness remains essentially unchanged. As the coating thins, the total thickness of the easily worn layer 4 decreases, consequently reducing the bending stiffness of this area. In other words, under the same pressure, this area is more prone to downward bending deformation. (See...) Figure 5 .

[0046] During the printing process, the squeegee itself undergoes slight elastic deformation. When the squeegee presses down, the pressure is not absolutely uniform. Above the easily worn layer 4, due to the reduced rigidity in this area, a larger local concave deformation will occur under the pressure of the squeegee than in the surrounding area. This amount of concavity just compensates for the microscopic gap between the metal screen and the uneven surface of the silicon wafer, allowing the screen surface around the pattern opening 2 to adhere to the silicon wafer surface. The point contact between the original hard plane and the microscopic uneven surface is transformed into a larger area surface contact, thus significantly improving the adhesion.

[0047] Meanwhile, the wear-resistant layer 3 maintains its full thickness and forms a high-rigidity support structure around the edge of the patterned opening 2. This support ensures that the geometric dimensions and shape of the patterned opening 2 do not change during long-term use, and the channel through which the slurry is squeezed out of the opening remains stable, thus ensuring the long-term consistency of the slurry permeability.

[0048] It should be noted that this localized concave deformation is dynamically generated under printing pressure. That is, the concavity is formed when the pressure is present, and the elasticity recovers or partially recovers after the pressure is removed. It is a dynamic bonding behavior during the printing process, and not a permanent macroscopic deformation of the metal mesh structure. The reduction in the thickness of the wear-resistant layer 3 only lowers the stiffness threshold for concave deformation in this area, so that sufficient deformation can be generated under the same printing pressure to compensate for the bonding gap.

[0049] The above description of the embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fully open metal mesh with a differentiated wear-resistant structure, comprising metal sheets, characterized in that, The metal sheet has multiple patterned openings that penetrate the metal sheet. During the printing process, a wear-resistant layer is disposed on the silicon wafer surface adjacent to the periphery of the patterned openings. An easy-wear layer is disposed adjacent to the periphery of the wear-resistant layer. The wear resistance of the wear-resistant layer is higher than that of the easy-wear layer and the metal sheet, while the wear resistance of the easy-wear layer is lower than that of the metal sheet.

2. The fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The wear-resistant layer extends outward from the edge of the pattern opening with a width of 30~80μm.

3. The fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The metal sheet is made of nickel or a nickel alloy.

4. The fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The wear-resistant layer is made of a nickel-based alloy plating.

5. A fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The material of the wear-resistant layer is a material whose wear resistance is significantly lower than that of the wear-resistant layer material, and the material of the wear-resistant layer does not produce harmful pollutants during the wear process.

6. A fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The materials of the wear-resistant layer and the wear-resistant layer are applied to the metal sheet by electroplating, PVD, or sputtering.

7. The method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure according to claim 1, characterized in that, The thickness range of the wear-resistant layer and the wear-resistant layer is 0.1~5μm.

8. A method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure, characterized in that, Includes the following steps: S1. A metal sheet with a patterned opening is produced by using a deposition process combined with dry film exposure and development technology. S2. On the side of the metal sheet facing the silicon wafer, a selective mask is applied. After the dry film is applied, it is exposed and developed to form a patterned mask. The mask covers the patterned opening area and the wear-resistant layer, exposing the wear-prone layer. S3. Deposit a low-wear-resistant material on the exposed wear-prone layer by electroplating, with a deposition thickness of 0.1~5μm; S4, Remove occlusion; S5. Apply selective masking again, apply dry film again, expose, and develop to form a patterned mask. The mask covers the patterned opening area and the easily worn layer, exposing the wear-resistant layer. S6. High wear-resistant material is deposited on the exposed wear-resistant layer by electroplating, with the deposition thickness being consistent with that of the wear-prone layer. S7. Remove the masking to obtain the finished metal mesh plate.

9. The method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure according to claim 8, characterized in that, In step S2, PVD or sputtering can also be used. If PVD or sputtering is used, a metal mask is used to cover the areas that do not need to be deposited, exposing the wear-prone layer.

10. A method for manufacturing a fully open metal mesh with a differentiated wear-resistant structure according to claim 9, characterized in that, In step S5, PVD or sputtering can also be used. If PVD or sputtering is used, a metal mask is used to cover the areas that do not need to be deposited, exposing the wear-resistant layer.

Images