Screen printing plate structure

Abstract

The utility model relates to the field of solar cells, and discloses a screen printing plate structure which comprises a screen printing plate body, the screen printing plate body comprises a first surface close to the solar cells and a second surface far away from the solar cells, the screen printing plate structure further comprises a plurality of wire grooves, and slurry penetrates through the wire grooves so that main grids and auxiliary grids can be formed on the solar cells through the slurry. And the plurality of reinforcing wires are arranged on the first surface and are connected with the screen printing plate body. By the adoption of the scheme, the excellent printing performance of the steel plate can be reserved, the tensile elasticity of the weak opening part is enhanced, and it is guaranteed that the overall printing strength of the steel plate is sufficient.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular to a screen structure. Background Art

[0002] In the solar cell industry, screen printing is primarily used to form the cell's electrodes. Printing is performed based on the principle that the screen's graphic portions are permeable to the slurry, while the non-graphic portions remain impermeable. Traditional knotless screens improve printability by removing knots from the printed pattern. However, due to limitations in the mesh structure, knots can only be removed in one direction. To reduce the difficulty of knot removal, the lines of the metal mesh in knotless screens are arranged at 0° or 90°, with the horizontal and vertical lines parallel to the screen frame. This arrangement helps reduce knots during fine grid printing and minimizes the amount of silver paste used. However, for patterns perpendicular to the fine grid, such as main grids, anti-breakage grids, and harpoons, the exact number of knots cannot be guaranteed during printing, which can result in unevenness in the printed pattern.

[0003] The electroformed steel screen is a new type of steel stamped screen. Due to its lack of steel wire interlacing, each grid line on the cell is a fully open hole stamped by the mold. This results in a printed cell with well-defined grid line morphology, even and smooth ink distribution, and a narrower shape. The narrower line width reduces the light-shielding area, increasing the cell's light absorption capacity and ultimately improving efficiency. However, the electroformed steel screen is a newly developed process, and the fully open structure of existing steel plates has greatly reduced elasticity. Openings must be made in the fine grid to ensure sufficient tensile strength across the entire surface of the steel plate. These openings overlap the main grid, so the grid line height required for welding is insufficient, which can easily lead to weld breakage, affecting the module and even preventing current transmission. Utility Model Content

[0004] An embodiment of the present application discloses a screen structure, which utilizes multiple reinforcing wires arranged on the screen surface away from the battery cells to ensure that the entire steel plate is evenly stressed. The addition of steel wires to the screen improves the tensile capacity and rebound strength and extends the service life of the screen.

[0005] In order to achieve the above objectives, the present application discloses a screen structure, including:

[0006] A screen body, the screen body comprising a first surface close to the solar cell and a second surface away from the solar cell, the screen structure further comprising a plurality of wire grooves, the wire grooves being used to allow the slurry to pass through so that the slurry forms a main grid and a secondary grid on the solar cell;

[0007] A plurality of reinforcing wires are disposed on the second surface and connected to the mesh body.

[0008] As an optional embodiment, the wire grooves include multiple first wire grooves and multiple second wire grooves, the first wire grooves are used to form the main grid lines of the solar cell, and the second wire grooves are used to form the secondary grid lines of the solar cell, and the multiple reinforcing wires all extend in a direction perpendicular to the second wire grooves and are arranged at intervals in a direction parallel to the second wire grooves.

[0009] As an optional embodiment, the multiple reinforcing wires are arranged at equal intervals.

[0010] As an optional embodiment, the distance between two adjacent reinforcing wires is 1.048 mm to 2.107 mm.

[0011] As an optional embodiment, the number of the plurality of reinforcing wires is 100-200.

[0012] As an optional embodiment, the plurality of reinforcing wires extend out of the mesh body along an extension direction of the reinforcing wires.

[0013] As an optional implementation, the positions of the plurality of second wire grooves corresponding to the welding strips are closed structures.

[0014] As an optional implementation, the diameter of the reinforcing wire is less than 6 μm.

[0015] As an optional implementation, the multiple reinforcement wires are made of stainless steel, chromium alloy steel or special alloy.

[0016] As an optional implementation, any of the wire grooves penetrates the screen structure along the thickness direction of the screen body.

[0017] As an optional implementation, the screen structure further includes a screen frame, and the screen frame is fixed around a periphery of the screen structure.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The embodiment of the present application utilizes multiple reinforcing wires arranged on the surface of the screen away from the battery cells to ensure that the entire steel plate is evenly stressed. The screen with the added steel wires has improved tensile strength and rebound strength, and extended the service life of the screen, reducing the screen from bending due to insufficient support force and the appearance of uneven grid lines in local areas; reducing the uneven distribution of slurry on the screen caused by the bending of the screen, and the area with more slurry may clog the holes, resulting in uneven ink distribution in the printing and the formation of jagged and undulating grid lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of a secondary grid printed by electroforming screen printing on a steel plate in the related art;

[0022] Figure 2 for Figure 1 A partial enlarged view of the corresponding welding strip position of the auxiliary grid;

[0023] Figure 3 for Figure 1 Cross-section of the steel electroformed screen in [1].

[0024] Figure 4 A schematic diagram of a screen structure disclosed in an embodiment of the present application;

[0025] Figure 5 for Figure 4 A schematic diagram of the first line slot of the screen structure;

[0026] Figure 6 for Figure 4 Schematic diagram of the second line slot of the screen structure;

[0027] Figure 7 for Figure 4 Schematic diagram of the main grid lines printed by the screen structure in FIG;

[0028] Figure 8 for Figure 4 Schematic diagram of the secondary grid lines printed by the screen structure in FIG;

[0029] Figure 9 for Figure 4 Schematic diagram of the reinforcing wire of the screen structure;

[0030] Figure 10 This is the process flow chart for screen structure printing.

[0031] Description of reference numerals:

[0032] 100-screen structure; 1-screen body; 11-first wire slot; 12-second wire slot; 2-reinforcement wire; 3-main grid line; 4-secondary grid line; 5-harpoon. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] In this application, the terms "upper" and "upper" and other terms indicating positions or locations are based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe this application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific position, or to being constructed or operated in a specific position.

[0035] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0036] Furthermore, the terms "disposed" and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0037] Furthermore, the terms "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (which may or may not be of the same type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0038] Solar cell screens are a key tool used for screen-printing electrodes in solar cell manufacturing. They typically consist of a screen frame and a mesh fabric, which is woven from interwoven metal threads. The intersections of the horizontal and vertical lines of the metal mesh are called knots. The presence of knots can affect the permeability of the slurry and, in turn, the screen's printing performance.

[0039] Traditional knotless screens improve printability by removing knots from the printed pattern. However, due to limitations in the mesh structure, knots can only be removed in one direction. To simplify knot removal, the lines of the metal mesh in knotless screens are arranged at 0° or 90°, with the horizontal and vertical lines parallel to the screen frame. This arrangement helps reduce knots when printing fine grids and reduces the amount of silver paste used. However, for patterns perpendicular to the fine grid, such as main grids, anti-break grids, and harpoons, the exact number of knots cannot be guaranteed during printing, which can result in unevenness in the printed pattern.

[0040] To overcome these problems, a steel electroformed screen can be used, see Figure 1 , Figure 1 This is a schematic diagram of the secondary grid printed by electroforming screen printing on a steel plate. Due to its characteristic of no steel wire interweaving, each grid line A on the cell is a fully open hole stamped by the mold. The printed cell has good grid line morphology, uniform and smooth ink distribution, and narrower molding. The narrow line width reduces the light-shielding area, increases the light absorption capacity of the cell, and ultimately helps improve efficiency. In addition, the steel plate has a lower cost, which can achieve the goal of improving efficiency and reducing costs. Figure 2 , Figure 2 for Figure 1 A partial enlarged view of the harpoon portion of the middle secondary grid. Since the grid line A after electroforming screen printing on the steel plate is fully open, the elasticity of the steel material is largely reduced. The openings in the fine grid A must be broken to ensure sufficient tensile strength across the entire steel plate. However, the broken harpoon portion B is located at the overlap area with the main grid. This insufficient height for welding the grid line can easily lead to weld failures, affecting the module and even preventing normal current transmission. Also, please refer to Figure 3 , Figure 3 for Figure 1 The cross-section of the electroformed screen of Zhonggangban. Compared with the traditional screen, without the assistance of steel wire, the steel plate as a whole is easily bent due to its own gravity due to insufficient tension and strength, resulting in the printed grid lines always being printed under irregular patterns. Slight impact is caused by uneven ink application affecting the line shape. Severe impact is caused by long-term uneven printing, which will cause the scraper to apply uneven force to the steel plate when printing back and forth, increasing the risk of printing explosion, increasing the frequency of screen replacement, and increasing material costs.

[0041] Based on this, the embodiment of the present application discloses a screen structure that retains the excellent printing performance of the steel plate while enhancing the tensile elasticity of its weak opening parts to ensure sufficient overall printing strength of the steel plate.

[0042] The technical solution of the present application will be further described below with reference to the embodiments and drawings.

[0043] See also Figure 4 , Figure 4This is a schematic diagram of a screen structure disclosed in an embodiment of the present application.

[0044] The embodiment of the present application discloses a screen structure for printing an electrode sheet of a solar cell. The screen structure 100 includes:

[0045] A screen body 1, wherein the screen body 1 includes a first surface close to the solar cell and a second surface away from the solar cell, the first surface contacts the solar cell, and the second surface contacts the scraper. The screen structure also includes a plurality of grooves for allowing the slurry to pass through the grooves so that the slurry forms a main grid and a secondary grid on the solar cell;

[0046] A plurality of reinforcing wires 2 are disposed on the first surface and connected to the mesh body 1 .

[0047] Specifically, the first surface of the screen body 1 contacts the solar cell, and the scraper contacts the second surface of the screen body 1. Slurry is poured onto one end of the second surface of the screen body 1, and the scraper is used to apply a certain amount of pressure to the slurry-containing area of ​​the second surface while moving toward the other end of the second surface. During movement, the slurry is squeezed from the mesh of the graphic portion by the scraper onto the solar cell. During the printing process, the scraper is always in line contact with the screen body 1 and the solar cell. The contact line moves with the movement of the scraper, while the other parts of the screen body 1 are separated from the solar cell, ensuring the printing dimensional accuracy and preventing the solar cell from being stained. When the scraper has scraped across the entire printing area, it is lifted, and the screen structure 100 is also separated from the solar cell. The ink return knife gently scrapes the slurry back to its original position, and the workbench returns to the loading position.

[0048] Among them, on the one hand, the multiple fully-open grid lines on the screen body 1 allow the slurry to pass through more evenly. By utilizing the fully-open characteristics of the steel plate, the main grid and auxiliary grid with a higher aspect ratio advantage are formed after the slurry is inked. Compared with the grid lines of conventional screen printing, there is less shading, which improves the overall conversion efficiency; on the other hand, multiple reinforcing wires are arranged on the first surface and connected to the screen body, which improves the tensile strength and wear resistance of the screen and extends the service life of the screen. During long-term and high-intensity printing processes, the reinforcing wires also help to maintain the shape and size of the screen stable, reducing the risk of deformation and damage to the screen.

[0049] See also Figures 5 to 8 , Figure 5 for Figure 4 Schematic diagram of the first line slot of the screen structure, Figure 6 for Figure 4 Schematic diagram of the second line slot of the screen structure, Figure 7 for Figure 4 Schematic diagram of the main grid lines printed by the screen structure in FIG; Figure 8 for Figure 4Schematic diagram of the secondary grid lines printed by the screen structure in FIG. In some embodiments, the grid lines include a plurality of first grid lines 11 and a plurality of second grid lines 12. The first grid lines 11 are used to form the main grid lines 3 of the solar cell, and the second grid lines 12 are used to form the secondary grid lines 4 of the solar cell. The plurality of reinforcing wires 2 extend in a direction perpendicular to the second grid lines 12 and are spaced apart and arranged in a direction parallel to the second grid lines 12.

[0050] In this way, multiple reinforcing wires 2 extend in a direction perpendicular to the second wire groove 12, and are arranged at intervals in a direction parallel to the second wire groove 12, which helps to evenly disperse the stress generated during the printing process, reduce the risk of deformation and damage of the screen structure 100, enhance the mechanical strength of the screen structure 100, extend the service life of the screen structure 100, and reduce the replacement frequency and maintenance costs.

[0051] See also Figure 9 , Figure 9 for Figure 4 Schematic diagram of the reinforcing wires of the screen structure in FIG. To further enhance the strength of the screen structure 100, in some embodiments, multiple reinforcing wires 2 may be arranged at equal intervals. This equal spacing of the reinforcing wires 2 helps maintain the flatness of the screen structure 100, thereby making the tension distribution during printing more uniform, helping to reduce deformation of the screen structure 100 caused by localized tension imbalances and improving printing quality.

[0052] It should be noted that the spacing between two adjacent reinforcing wires 2 is 1.048mm-2.107mm, and the number of reinforcing wires 2 corresponding to the spacing is 100-200. Taking 200 reinforcing wires 2 as an example, when the number of reinforcing wires 2 is 200, the 200 reinforcing wires 2 are evenly divided into 208.6×208.6, that is, 43,513.96mm. 2 The effective area of ​​the solar cell is distributed at a spacing of 1.048 mm. In this way, on the one hand, the number of required reinforcing wires 2 can be selected according to actual conditions to adapt to different working environments or needs. On the other hand, the evenly distributed reinforcing wires 2 help to maintain the flatness of the screen structure 100, ensure the uniform distribution of the slurry during the printing process, reduce printing defects such as broken grids and virtual printing, ensure the consistency of each printing, make the electrode pattern of each solar cell highly consistent, and improve the product yield. The embodiment of the present application does not impose too many restrictions on the number and spacing of the reinforcing wires 2.

[0053] See also Figure 4In order to distribute the supporting force provided by the reinforcing wires 2 to all parts of the screen structure 100, optionally, multiple reinforcing wires 2 extend out of the screen body 1 along the extension direction of the reinforcing wires 2, wherein the reinforcing wires 2 extend from the screen body 1, providing additional mechanical strength, especially in stress-concentrated areas such as edges and corners of the screen structure 100, thereby extending the service life of the screen structure 100.

[0054] It should be noted that the diameter of the above-mentioned reinforcing wire 2 is less than 6um. Specifically, the wire diameter of the reinforcing wire 2 is selected to be 6um and less than 6um. This is because it is different from the knotless steel wire of the conventional screen. The conventional screen requires a certain degree of thickness to ensure that the number of holes formed by interweaving is sufficient to ensure printing clarity, usually with a wire diameter of 7um; and the reinforcing wire 2 only needs to provide sufficient supporting strength, without considering factors such as the number of holes, and the smaller the wire diameter of the reinforcing wire 2, the smaller the impact of the reinforcing wire 2 on printing ink drop, and the better the printed grid line effect.

[0055] To solve the problem of insufficient grid height during welding, which may cause welding failure, affect the components and even prevent the normal transmission of current, please refer to Figures 4 to 8 In some embodiments, multiple second wire grooves 12 harpoons 5 are closed structures. Specifically, the main function of the above-mentioned welding ribbon is to connect the solar cell so as to collect the current generated by the photovoltaic effect and transmit this current to the external circuit, and the welding ribbon will cover the entire main grid line 3. The position of the second wire groove 12 corresponding to the welding ribbon is a closed structure, that is, the auxiliary grid line 4 harpoon 5 is partially disconnected. On the one hand, the partial disconnection of the auxiliary grid line 4 harpoon 5 can make room for the welding ribbon to avoid contact with the grid line during welding, reduce the risk of short circuit during welding, reduce the welding temperature, thereby reducing thermal damage to the battery cell, and also help to improve the accuracy and reliability of welding. On the other hand, the disconnection at other positions can make the wire grooves of the screen structure 100 have connected parts, further improving the supporting strength of the screen structure 100.

[0056] It should be noted that the material of the above-mentioned reinforcing wire 2 is stainless steel, chromium alloy steel or special alloy, which is corrosion-resistant and has high strength. Taking stainless steel as an example, stainless steel is a steel containing alloy elements such as chromium, nickel, and molybdenum. The chromium element in stainless steel reacts with oxygen to form a dense sodium chromate layer, which can effectively reduce the probability of corrosion; stainless steel has high strength and can withstand greater pressure and tension; stainless steel has strong high and low temperature resistance and can maintain good physical and chemical properties in different temperature environments; taking chromium alloy steel as an example, chromium alloy steel is an alloy made by adding chromium elements to ordinary steel. Chromium alloy steel usually has good high temperature strength and oxidation resistance; because the addition of chromium elements can significantly improve the hardness and wear resistance of steel, chromium can also promote the formation of a protective oxide film on the surface, thereby improving the corrosion resistance of the material. The embodiment of this application does not limit the material of the reinforcing wire.

[0057] In order to further improve the printing effect of the grid lines, in some embodiments, any line groove passes through the screen structure 100 along the thickness direction of the screen body 1, so the flatness of the secondary grid line 4 structure obtained by printing the solar cell is good, especially for the intersection area of ​​the main grid line 3 and the secondary grid line 4. The height of the slurry after printing in this area is relatively high, which is beneficial to the subsequent welding of photovoltaic modules, reduces the phenomenon of grid breakage during welding, ensures the stability of welding, and thus helps to improve the photoelectric conversion efficiency of solar cells.

[0058] Furthermore, the screen structure 100 also includes a screen frame. The screen structure 100 is arranged in the screen frame, and the screen frame is fixed around the screen structure 100. On the one hand, the screen frame provides a solid external support for the screen structure 100, enhances the overall rigidity and stability, and makes it less likely to deform during use; the screen frame fixes the screen structure 100 to ensure that it maintains the correct position and shape during operation, thereby improving the accuracy of printing or molding. The stable screen frame design enables it to maintain consistent performance after multiple uses, thereby improving the repeatability and consistency of production; on the other hand, the screen frame can protect the screen structure 100 from damage from the external environment, such as impact, wear, etc., thereby extending the service life of the entire screen structure 100.

[0059] See also Figure 10 ,in Figure 10 FIG. 1 is a process flow chart for printing the screen structure 100 . The process flow for printing the screen structure 100 includes the following steps:

[0060] Step 1: Pour slurry into one end of the screen structure 100 during printing.

[0061] Step 2: Use a scraper to apply pressure to the slurry area of ​​the screen structure 100 while moving toward the other end of the screen structure 100. As the scraper moves, the slurry is squeezed through the first and second grooves 11 and 12 in the pattern area and onto the substrate. During the printing process, the scraper is always in line contact with the screen structure 100 and the cell. The contact line moves with the scraper, while the rest of the screen structure 100 is separated from the cell, ensuring dimensional accuracy and preventing contamination of the cell.

[0062] Step 3: When the scraper has scraped across the entire printing area, it is lifted up and the screen is separated from the substrate.

[0063] Step 4: Use the ink return knife to gently scrape the slurry back to the initial position, and the workbench returns to the loading position. This completes a complete printing stroke.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A screen structure for printing electrodes for solar cells, characterized in that: The screen structure includes: A screen body, the screen body comprising a first surface close to the solar cell and a second surface away from the solar cell, the screen structure further comprising a plurality of wire grooves, the wire grooves being used to allow the slurry to pass through so that the slurry forms a main grid and a secondary grid on the solar cell; A plurality of reinforcing wires are disposed on the first surface and connected to the mesh body.

2. The screen structure according to claim 1, characterized in that: The wire grooves include a plurality of first wire grooves and a plurality of second wire grooves, the first wire grooves are used to form the main grid lines of the solar cell, the second wire grooves are used to form the secondary grid lines of the solar cell, and the plurality of reinforcing wires extend in a direction perpendicular to the second wire grooves and are arranged at intervals in a direction parallel to the second wire grooves.

3. The screen structure according to claim 2, characterized in that: The plurality of reinforcing wires are arranged at equal intervals.

4. The screen structure according to claim 3, characterized in that: The distance between two adjacent reinforcing wires is 1.048 mm to 2.107 mm.

5. The screen structure according to claim 4, characterized in that: The number of the plurality of reinforcing wires is 100-200.

6. The screen structure according to claim 2, characterized in that: The plurality of reinforcing wires extend out of the mesh body along an extending direction of the reinforcing wires.

7. The screen structure according to claim 2, characterized in that: The positions of the plurality of second wire grooves corresponding to the welding strips are closed structures.

8. The screen structure according to claim 1, characterized in that: The diameter of the reinforcing wire is less than 6 μm.

9. The screen structure according to claim 1, characterized in that: The material of the multiple reinforcement wires is stainless steel or chromium alloy steel.

10. The screen structure according to claim 1, characterized in that: Any of the wire grooves passes through the screen structure along the thickness direction of the screen body.

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