screen structure

Abstract

The application discloses a screen structure and relates to the technical field of photovoltaics.The screen structure comprises a screen body, which has a scraping side and a pasting side arranged oppositely, and the screen body comprises an alignment mark opening penetrating through the screen body; a filament structure is arranged on the scraping side of the screen body and is arranged correspondingly to the alignment mark opening, the filament structure comprises a plurality of metal wires, and a plurality of the metal wires are provided with a plurality of hollow parts which are communicated with the alignment mark opening; wherein the wire diameter of the metal wire is within a target wire diameter range, and the size of the hollow part is within a target size range, that is, the metal wire with a specific wire diameter and the hollow part with a specific size are arranged in the alignment mark area to ensure that the alignment mark area is released slowly and rigidly and sufficiently in the printing process, periodic stress concentration in the alignment mark area is relieved, and the phenomenon of slurry leakage in the alignment mark area and the like is reduced or even avoided, printing defects are improved, and the electrical performance of a battery piece is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically to a screen structure. Background Technology

[0002] In the printing process, the alignment mark area of ​​the screen structure (such as steel screen) in related technologies is prone to periodic stress concentration, which leads to ink leakage, resulting in poor printing and affecting the electrical performance of the solar cells. Summary of the Invention

[0003] This invention discloses a screen printing structure to solve the problem of poor printing caused by ink leakage in the alignment mark area, which affects the electrical performance of the battery cell.

[0004] In a first aspect, the present invention discloses a screen printing structure, comprising: a screen printing body having a squeegee side and a printing side disposed opposite to each other, the screen printing body including a alignment mark opening penetrating the screen printing body; and a filament structure disposed on the squeegee side of the screen printing body and correspondingly disposed to the alignment mark opening, the filament structure including a plurality of metal wires, the plurality of metal wires having a plurality of hollow portions communicating with the alignment mark opening; wherein the wire diameter of the metal wires is within a target wire diameter range, and the size of the hollow portions is within a target size range.

[0005] In some embodiments of the present invention, the target wire diameter ranges from 0.5 μm to 4 μm.

[0006] In some embodiments of the present invention, a plurality of the metal wires are spaced apart, and the hollow portion is located between two adjacent metal wires.

[0007] In some embodiments of the present invention, the size of the hollow portion includes the width of the hollow portion, the width of the hollow portion is equal to the distance between two adjacent metal wires, and the target size range is 1.5μm~10μm.

[0008] In some embodiments of the present invention, the plurality of metal wires include a plurality of first metal wires spaced apart and a plurality of second metal wires spaced apart, the plurality of first metal wires and the plurality of second metal wires being intersected and arranged in a hollowed-out mesh structure, and the hollowed-out portion including the hollowed-out mesh in the hollowed-out mesh structure.

[0009] In some embodiments of the present invention, the size of the hollowed-out portion includes the diagonal dimension of the hollowed-out mesh, and the target size range is... μm~ μm.

[0010] In some embodiments of the present invention, the screen printing body further includes a grid line opening penetrating the screen printing body; the screen printing body is a rigid screen printing body, and the grid line opening is a full opening; and / or, the alignment mark opening is tangentially disposed to the grid line opening.

[0011] In some embodiments of the present invention, the screen printing plate body includes a first functional layer and at least one second functional layer sequentially stacked between the printing side and the squeegee side; the hardness of the first functional layer is less than the hardness of the battery cell, and the hardness of the second functional layer is greater than the hardness of the first functional layer.

[0012] In some embodiments of the present invention, the Mohs hardness of the first functional layer is 1 to 4.5.

[0013] In some embodiments of the present invention, the material of the first functional layer includes at least one of a Bi-Sn binary alloy system, a Bi-Sn-Al ternary alloy system, a Bi-Sn-Al-Zn quaternary alloy system, and a conductive polymer material; and / or, the material of the second functional layer includes at least one of a Ni-W binary alloy system and a nickel alloy.

[0014] This invention discloses a screen printing structure. A filamentous structure is provided on the squeegee side of the screen printing body, and the filamentous structure is correspondingly arranged with the alignment mark opening. The filamentous structure includes multiple metal wires, and multiple hollow portions connected to the alignment mark opening are provided between the multiple metal wires. The wire diameter is within the target wire diameter range, and the size of the hollow portions is within the target size range. That is, by setting metal wires of a specific wire diameter and hollow portions of a specific size in the alignment mark area, the rigidity of the alignment mark area is slowly and fully released during the printing process, which alleviates the periodic stress concentration in the alignment mark area, thereby reducing or even avoiding the occurrence of phenomena such as ink leakage in the alignment mark area, improving printing defects, and enhancing the electrical performance of the battery cell. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the background art, the accompanying drawings used in the embodiments of the present invention or the background art will be described below.

[0016] Figure 1 This is a top view of a screen printing structure disclosed in an embodiment of the present invention.

[0017] Figure 2 This is a partial cross-sectional schematic diagram of a screen printing structure disclosed in an embodiment of the present invention.

[0018] Figure 3 This is a partial top view of a screen printing structure disclosed in an embodiment of the present invention.

[0019] Figure 4 This is a top view of a filament structure in the screen printing structure disclosed in an embodiment of the present invention.

[0020] Figure 5 This is a top view of another filament structure in the screen printing structure disclosed in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will now be described with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] TOPCon photovoltaic technology, due to its high conversion efficiency, has become a research hotspot and development direction in the photovoltaic field in recent years. With social development, the demand for cost reduction and efficiency improvement in TOPCon has become increasingly urgent, and the design of the TOPCon cell electrode structure is a crucial issue in achieving this. The electrode structure of the solar cell mainly adopts a configuration of multiple main grid lines and multiple sub-grid lines arranged perpendicularly to each other. Traditional screen printing structures (wire-interwoven screens) produce wider grid lines, resulting in excessively high light-blocking area and insufficient light-receiving area on the cell surface, thus limiting the cell's conversion efficiency. Furthermore, the excessive amount of silver paste used for printing the grid lines leads to high cell costs.

[0023] To address the problems associated with traditional screen printing structures, a novel screen printing structure (steel screen) is employed. This structure features fully open openings for printing the grid lines. Due to the absence of interwoven steel wires, the printed grid lines exhibit superior morphology, characterized by uniform and smooth ink application and narrower line widths. The reduced line width decreases the light-blocking area, increasing the light absorption capacity of the solar cell and significantly improving efficiency. However, the significantly increased rigidity of the steel screen compared to traditional interwoven steel wire screens leads to periodic stress concentration in the alignment marking area during the screen printing process. This causes fatigue fracture of the steel wires in the alignment marking area, resulting in ink leakage and ultimately, printing defects that negatively impact the battery's electrical performance.

[0024] Based on this, the present invention discloses a screen printing structure. By setting a filamentous structure on the squeegee side of the screen printing body, the filamentous structure is correspondingly set with the alignment mark opening. The filamentous structure includes multiple metal wires, and multiple hollow portions connected to the alignment mark opening are between the multiple metal wires. The wire diameter is within the target wire diameter range, and the size of the hollow portions is within the target size range. That is, by setting metal wires of a specific wire diameter and hollow portions of a specific size in the alignment mark area, the rigidity of the alignment mark area is slowly and fully released during the printing process, which alleviates the periodic stress concentration in the alignment mark area, avoids local overload at the cutter end causing metal wire breakage, thereby reducing or even avoiding the occurrence of phenomena such as ink leakage in the alignment mark area, improving printing defects, and enhancing the electrical performance of the battery cell.

[0025] As an optional implementation of the disclosure of this invention, an embodiment of this invention discloses a screen structure that can be applied to solar cells.

[0026] Figure 1 This is a top view of a screen printing structure disclosed in an embodiment of the present invention. Figure 2 This is a cross-sectional structural diagram of a screen printing plate structure disclosed in an embodiment of the present invention. Figure 1 and Figure 2 As shown, the screen printing structure includes a screen printing body 1 and a filament structure 2.

[0027] The screen body 1 has a squeegee side and a printing side arranged opposite to each other. The squeegee side and the printing side are located on opposite sides of the thickness direction of the screen body 1. The squeegee side is the side where the squeegee applies and receives the conductive paste (such as silver paste), and the printing side is the side closer to the solar cell. During the printing process, the printing side of the screen body 1 is in close contact with the surface of the solar cell 3. The paste enters the screen body 1 through the squeegee side and is then printed onto the surface of the solar cell 3 through the printing side. For example... Figure 1 The upper side of the screen printing body 1 shown is the scraping side, and the lower side is the pasting side.

[0028] The screen printing plate body 1 includes an alignment mark opening 12 that penetrates the screen printing plate body 1. The alignment mark opening 12 is used to allow paste to pass through to print alignment mark points on the surface of the solar cell 3, so that subsequent processes can perform precise alignment based on the alignment mark points.

[0029] The alignment mark opening 12 penetrates the screen body 1 along the thickness direction. The sidewall of the alignment mark opening 12 can be inclined outward, that is, the orthographic projection of the bottom of the alignment mark opening 12 on the screen body 1 can be smaller than the orthographic projection of the top of the alignment mark opening 12 on the screen body 1.

[0030] The cross-section of the alignment mark opening 12 perpendicular to the thickness direction can be circular, rectangular, or the like. Of course, the present invention is not limited to this. In other embodiments, the cross-section of the alignment mark opening 12 perpendicular to the thickness direction can also be rhomboid, cross-shaped, or the like, which will not be elaborated here.

[0031] There can be multiple alignment mark openings 12, which can be distributed at intervals along the edge region of the screen body 1. For example, there can be four alignment mark openings 12, which are located at the four corners of the screen body 1.

[0032] The filamentary structure 2 is disposed on the squeegee side of the screen body 1 and corresponds to the alignment mark opening 12. The area where the filamentary structure 2 is located can completely cover the alignment mark opening 12. The filamentary structure 2 and the alignment mark opening 12 constitute the alignment mark area. The filamentary structure 2 is connected to the screen body 1 around the alignment mark opening 12. In some embodiments of the present invention, the filamentary structure 2 and the screen body 1 are integrally formed.

[0033] The filamentary structure 2 includes multiple metal wires 21, and each metal wire 21 has multiple cutouts 22 that communicate with the alignment mark opening 12. Each metal wire 21 extends in a direction that can be the same or different. The orthographic projection of each metal wire 21 onto the screen body 1 intersects with the alignment mark opening 12, and both ends of each metal wire 21 are connected to the screen body 1 surrounding the alignment mark opening 12.

[0034] Multiple metal wires 21 may intersect or not (e.g., multiple metal wires 21 are arranged in parallel). The multiple metal wires 21 form a cutout 22, which is connected to the alignment mark opening 12 to ensure that the paste is printed onto the surface of the battery cell 3 through the cutout 22 of the filament structure 2 and the alignment mark opening 12 of the screen body 1.

[0035] The diameter of the metal wire 21 falls within the target diameter range. The diameter of the metal wire 21 cannot be too small to avoid fatigue breakage during printing, which could lead to ink leakage; nor can the diameter be too large to avoid poor ink flow, broken lines, or partial missing parts of the printing alignment marks. The lower limit of the target diameter range is greater than the diameter of the steel wire in related technologies, meaning that the metal wire 21 is thicker than the steel wire in related technologies.

[0036] The size of the cutout portion 22 is within the target size range. The size of the cutout portion 22 should not be too small to avoid poor ink flow, broken lines or partial missing parts of the printed alignment marks; the size of the cutout portion 22 should not be too large to avoid ink leakage.

[0037] In this embodiment of the invention, a filament structure 2 is provided on the squeegee side of the screen printing body 1, and the filament structure 2 is correspondingly provided with the alignment mark opening 12 to provide rigid reinforcement to the alignment mark opening 12, disperse the squeegee operating pressure, and suppress cracking and deformation of the opening film layer. Moreover, by setting metal wires 21 of a specific diameter and hollow parts 22 of a specific size, the filament structure 2 ensures that the rigidity of the alignment mark area is released slowly and fully during the printing process, alleviates the periodic stress concentration in the alignment mark area, avoids local overload at the blade retraction position that could cause the metal wires 21 to break, thereby reducing or even avoiding the occurrence of phenomena such as ink leakage in the alignment mark area, improving printing defects, and enhancing the electrical performance of the battery cell.

[0038] In some embodiments of the present invention, the metal wire 21 includes steel wire, and the material of the steel wire may include stainless steel, which has good tensile strength and corrosion resistance.

[0039] In some embodiments of the present invention, combined with Figure 3 As shown, the screen body 1 also includes a grid line opening 11 that penetrates the screen body 1. The grid line opening 11 is used to allow paste to pass through in order to print grid lines on the surface of the solar cell 3. The grid line can be a main grid line or a sub-grid line, that is, the grid line opening 11 can be a main grid line opening or a sub-grid line opening.

[0040] The grid opening 11 extends through the screen body 1 along the thickness direction. The sidewall of the grid opening 11 can be inclined outward, that is, the orthographic projection of the bottom of the grid opening 11 on the screen body 1 can be smaller than the orthographic projection of the top of the grid opening 11 on the screen body 1.

[0041] The grid opening 11 can extend along a first direction. There can be multiple grid openings 11, which can be spaced apart along a second direction. The first direction, the second direction, and the thickness direction are perpendicular to each other.

[0042] The screen body 1 is a rigid screen body, and the grid opening 11 is fully open. The screen body 1 has high rigidity to ensure that the grid opening 11 is fully open. The grid opening 11 is a completely hollow area, that is, there are no obstructions inside the grid opening 11, and no steel wires to block it. The ink passes through more smoothly and evenly, which can print finer grid lines, reduce the light-blocking area of ​​the solar cell, improve the light absorption capacity of the solar cell, improve the conversion efficiency, and use less ink, thus reducing the cost of the solar cell.

[0043] In some embodiments of the present invention, the alignment mark opening 12 is tangentially disposed with the gate line opening 11, that is, the outer contour of the alignment mark opening 12 is in contact with the outer contour of the gate line opening 11.

[0044] When the screen body 1 includes multiple grid line openings 11 arranged in parallel, the alignment mark opening 12 can be located between two adjacent grid line openings 11, and the alignment mark opening 12 is tangent to the two adjacent grid line openings 11 respectively.

[0045] In this embodiment of the invention, the alignment mark opening 12 is tangential to the grid line opening 11, which enables precise alignment during the screen printing process of the battery cell.

[0046] In some embodiments of the present invention, the diameter of the metal wire 21 is L1, while the diameter of the steel wire in related technologies is L0. This enables the thickening setting of metal wire 21.

[0047] In some embodiments of the present invention, the target wire diameter range is 0.5μm to 4μm, that is, the wire diameter L1 of the metal wire 21 is 0.5μm to 4μm. As an example, the wire diameter L1 of the metal wire 21 can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, etc.

[0048] The wire diameter L1 of different metal wires 21 can be the same or different, as long as the wire diameter L1 of each metal wire 21 is between 0.5μm and 4μm.

[0049] The aforementioned target wire diameter range was determined through extensive printing experiments and simulation analysis. If the wire diameter is less than 0.5 μm, the cross-sectional area of ​​a single wire is too small, and the bending stress generated inside the wire during printing quickly exceeds its fatigue limit, making it prone to breakage during repeated printing, resulting in ink leakage in the alignment mark area. If the wire diameter is greater than 4 μm, the arrangement of multiple wires will compress the total ink penetration area of ​​the cutout, leading to poor ink flow, broken lines or partial missing parts of the printed alignment marks. Therefore, setting the wire diameter L1 of the wire 21 within the aforementioned target wire diameter range ensures a reasonable ink penetration area during printing, while avoiding ink leakage caused by fatigue breakage of the wire 21, thus improving the printing quality of the alignment marks.

[0050] The multiple metal wires 21 in the filamentous structure 2 can be arranged in various ways. The morphology and arrangement of the multiple hollow parts 22 between the multiple metal wires 21 are different depending on the arrangement of the multiple metal wires 21.

[0051] In some embodiments of the present invention, combined with Figure 4 As shown, multiple metal wires 21 are distributed at intervals, and the hollowed-out part 22 is located between two adjacent metal wires 21.

[0052] Multiple metal wires 21 are arranged without crossing each other; for example, multiple metal wires 21 can be arranged in parallel or not in parallel. A cutout portion 22 is provided between any two adjacent metal wires 21, and multiple cutout portions 22 are distributed at intervals. The extension direction of the cutout portions 22 can be consistent with that of the metal wires 21, and the direction in which the multiple cutout portions 22 are distributed at intervals can also be consistent with the direction in which the multiple metal wires 21 are distributed at intervals.

[0053] As an example, each metal wire 21 extends along a first direction, and multiple metal wires 21 are spaced apart along a second direction. Each cutout portion 22 extends along the first direction, and multiple cutout portions 22 are spaced apart along the second direction. Each cutout portion 22 forms a narrow rectangular or approximately rectangular slit.

[0054] The multiple metal wires 21 can be evenly distributed or non-uniformly distributed, meaning that the spacing between adjacent metal wires 21 can be the same or different. As an example, the spacing between metal wires 21 near the center of the alignment mark area can be relatively large to improve ink penetration; the spacing between metal wires 21 near the edge of the alignment mark area can be relatively small to enhance support.

[0055] In this embodiment of the invention, multiple metal wires 21 are spaced apart, which effectively alleviates the periodic stress concentration generated in the alignment mark area during the printing process and avoids the breakage of the metal wires 21.

[0056] In some embodiments of the present invention, when multiple metal wires 21 are spaced apart, the size of the cutout portion 22 includes the width L2 of the cutout portion 22, which is equal to the distance between two adjacent metal wires 21. When the multiple metal wires 21 are not arranged in parallel, the width L2 of the cutout portion 22 refers to the maximum width of the cutout portion 22, that is, the maximum distance between two adjacent metal wires 21.

[0057] The target size range is 1.5μm to 10μm, that is, the width L2 of the cutout portion 22 is 1.5μm to 10μm. As an example, the width L2 of the cutout portion 22 can be 1.5μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc.

[0058] The width L2 of different cutouts 22 can be the same or different, as long as the width L2 of each cutout 22 is between 1.5μm and 10μm.

[0059] The aforementioned target size range was determined through extensive printing experiments and simulation analysis. If the width of the cutout is less than 1.5 μm, it can easily lead to poor ink flow, broken lines or partial missing parts of the printed alignment marks; if the width of the cutout is greater than 10 μm, it can easily lead to insufficient support strength and ink leakage in the alignment mark area. Therefore, the width L2 of the cutout 22 is set within the aforementioned target size range to ensure a reasonable ink penetration area during printing and improve the printing quality of the alignment marks.

[0060] In some embodiments of the present invention, combined with Figure 5 As shown, the plurality of metal wires 21 include a plurality of first metal wires 21a and a plurality of second metal wires 21b that are spaced apart. The plurality of first metal wires 21a and the plurality of second metal wires 21b are intersected and arranged in a hollowed-out grid structure. The hollowed-out part 22 includes the hollowed-out grid in the hollowed-out grid structure.

[0061] Multiple first metal wires 21a are arranged without crossing each other. For example, multiple first metal wires 21a can be arranged in parallel or not in parallel. Multiple first metal wires 21a can be evenly distributed or non-uniformly distributed, that is, the spacing between adjacent first metal wires 21a can be the same or different.

[0062] Multiple second metal wires 21b are arranged without crossing each other. For example, multiple second metal wires 21b can be arranged in parallel or not in parallel. Multiple second metal wires 21b can be evenly distributed or non-uniformly distributed, that is, the spacing between adjacent second metal wires 21b can be the same or different.

[0063] The spacing between two adjacent first metal wires 21a and the spacing between two adjacent second metal wires 21b can be the same or different.

[0064] Multiple first metal wires 21a and multiple second metal wires 21b are interspersed. Each first metal wire 21a may intersect with a portion of the second metal wires 21b, or it may intersect with every single second metal wire 21b. Each second metal wire 21b may intersect with a portion of the first metal wires 21a, or it may intersect with every single first metal wire 21a. Two adjacent first metal wires 21a and two adjacent second metal wires 21b form a perforated grid. Each perforated grid can be a perforated section 22, i.e., the perforated section 22 is quadrilateral.

[0065] In this embodiment of the invention, the first metal wire 21a and the second metal wire 21b are intersected to form a hollow grid structure, which further alleviates the periodic stress concentration generated in the alignment mark area during the printing process and avoids the breakage of the metal wire 21.

[0066] In some embodiments of the present invention, some of the first metal wires 21a are intersected with multiple second metal wires 21b to form a hollowed-out mesh structure, while the remaining first metal wires 21a are not intersected with the second metal wires 21b. The hollowed-out portion 22 can be a hollowed-out mesh in the hollowed-out mesh structure, or it can be a hollowed-out structure between two adjacent first metal wires 21a in the remaining first metal wires 21a.

[0067] In some embodiments of the present invention, some of the second metal wires 21b are distributed intersectingly with multiple first metal wires 21a to form a hollowed-out mesh structure, while the remaining second metal wires 21b are not distributed intersectingly with the first metal wires 21a. The hollowed-out portion 22 can be a hollowed-out mesh in the hollowed-out mesh structure, or it can be a hollowed-out structure between two adjacent second metal wires 21b among the remaining second metal wires 21b.

[0068] In some embodiments of the present invention, the crossing angle between the first metal wire 21a and the second metal wire 21b is θ, where 0° < θ < 180°. As an example, θ = 90°.

[0069] In some embodiments of the present invention, a plurality of first metal wires 21a are parallel and uniformly distributed, a plurality of second metal wires 21b are parallel and uniformly distributed, and each first metal wire 21a and each second metal wire 21b are arranged perpendicularly to each other.

[0070] As an example, each first metal wire 21a extends along a first direction, and multiple first metal wires 21a are spaced apart along a second direction. Each second metal wire 21b extends along the second direction, and multiple second metal wires 21b are spaced apart along the first direction. The spacing between adjacent first metal wires 21a is the same as the spacing between adjacent second metal wires 21b. Each first metal wire 21a and each second metal wire 21b are intersected. Two adjacent first metal wires 21a and two adjacent second metal wires 21b form a square perforated grid.

[0071] In some embodiments of the present invention, the size of the cutout portion 22 includes the diagonal dimension L3 of the cutout mesh. When the cutout mesh is not square, the diagonal dimension L3 of the cutout mesh refers to the maximum diagonal dimension of the cutout mesh, that is, the size of the cutout portion 22 includes the maximum diagonal dimension of the cutout mesh.

[0072] Target size range is μm~ μm, that is, the diagonal dimension L3 of the hollowed-out mesh is μm~ μm. As an example, the diagonal dimension L3 of the perforated mesh can be μm. μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, μm, etc.

[0073] The diagonal dimension L3 of different perforated grids can be the same or different, ensuring that the diagonal dimension L3 of each perforated grid is located within the specified range. μm~ μm is sufficient.

[0074] The target size range mentioned above was determined through extensive printing experiments and simulation analysis. If the diagonal dimension of the perforated grid is smaller than... If the size is too small (μm), it can easily lead to poor ink flow, broken lines or partial missing parts of the printing alignment marks; if the diagonal size of the cutout grid is larger than μm, it can cause problems. If the diameter is too small (μm), it can easily lead to insufficient support strength and ink leakage in the alignment mark area. Therefore, setting the diagonal dimension L3 of the perforated grid within the above-mentioned target size range can ensure a reasonable ink penetration area during the printing process and improve the printing quality of the alignment mark points.

[0075] In some embodiments of the present invention, the screen printing plate body 1 includes a first functional layer 13 and at least one second functional layer 14 sequentially stacked between the printing side and the squeegee side. The hardness of the first functional layer 13 is less than the hardness of the battery cell 3.

[0076] The first functional layer 13 is positioned closest to the solar cell 3. During the printing process, the first functional layer 13 adheres to the solar cell 3. The hardness of the first functional layer 13 is less than that of the solar cell 3, allowing the screen body 1 and the micro-undulating surface of the solar cell 3 to form a tight fit. This ensures that the ink is accurately deposited on the surface of the solar cell 3 after passing through the screen body 1, preventing ink from overflowing from the gaps between the screen body 1 and the uneven areas of the solar cell 3. This ensures that the printed grid lines have a uniform and regular shape, which not only reduces ink consumption during the printing process and achieves a stable and controllable mass production process, but also helps to improve the photoelectric conversion efficiency and overall electrical performance of the solar cell.

[0077] In some embodiments of the present invention, the hardness of the second functional layer 14 is greater than that of the first functional layer 13. This ensures that the screen body 1 composed of the first functional layer 13 and the second functional layer 14 is a rigid screen body, ensuring close contact between the screen body 1 and the battery cell 3 during printing, while also improving the rigidity of the screen body 1, allowing the grid opening 11 to be fully open.

[0078] In some embodiments of the present invention, the screen printing plate body 1 includes a plurality of second functional layers 14, and the hardness of the plurality of second functional layers 14 gradually increases in the direction away from the first functional layer 13. This ensures close contact between the screen printing plate body 1 and the battery sheet 3 during the printing process while further improving the rigidity support of the screen printing plate body 1.

[0079] In some embodiments of the present invention, the Mohs hardness of the first functional layer 13 is 1 to 4.5. As an example, the Mohs hardness of the first functional layer 13 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, etc.

[0080] The hardness parameter of the first functional layer 13 needs to be precisely controlled. If the Mohs hardness of the first functional layer is less than 1, the first functional layer is too soft and does not meet the rigidity requirements of the screen body 1; if the Mohs hardness of the first functional layer is greater than 4.5, the first functional layer cannot form a tight fit with the micro-undulation surface of the battery cell, which can easily lead to leakage.

[0081] In addition, the materials of the solar cells typically include monocrystalline silicon, polycrystalline silicon, etc., and the Mohs hardness of the solar cells is approximately 6.5. The Mohs hardness of the first functional layer 13 is set within the above range so that the Mohs hardness of the first functional layer 13 is less than the Mohs hardness of the solar cell 3, ensuring that the screen body 1 and the micro-undulation surface of the solar cell 3 form a tight fit, avoiding slurry leakage, while ensuring the rigidity requirements of the screen body 1.

[0082] In some embodiments of the present invention, the material of the first functional layer 13 includes at least one of Bi-Sn binary alloy system, Bi-Sn-Al ternary alloy system, Bi-Sn-Al-Zn quaternary alloy system and conductive polymer material.

[0083] Bismuth-tin based alloys naturally possess low hardness and good electroforming capabilities. By adjusting the alloy element ratios, their Mohs hardness can be precisely controlled to the desired range. Furthermore, these alloys readily deposit to form a uniform, dense layer during electroforming. Conductive polymers also exhibit low hardness, and their Mohs hardness can be precisely controlled to the desired range.

[0084] In some embodiments of the present invention, the material of the second functional layer 14 includes at least one of a Ni-W binary alloy system and a nickel alloy. The materials of the multiple functional layers 14 may be the same or different.

[0085] Nickel-tungsten alloys and nickel alloys both have high elastic modulus, high yield strength and excellent corrosion resistance, which can improve the rigidity support of the screen body 1 and withstand the mechanical and chemical erosion of long-term printing operations.

[0086] In some embodiments of the present invention, the screen structure further includes an ink storage layer (not shown in the figure), which is located on the squeegee side of the screen body 1. The ink storage layer includes an alignment mark ink storage opening that penetrates the ink storage layer. The alignment mark ink storage opening is correspondingly disposed with the alignment mark opening 12. A filament structure 2 is disposed at the bottom of the alignment mark ink storage opening, and the hollow portion 22 in the filament structure 2 is connected to the alignment mark ink storage opening and the alignment mark opening 12 respectively.

[0087] The alignment mark ink storage opening is used to store ink, so that ink can be continuously supplied to the alignment mark opening 12 through the perforated part 22, avoiding ink shortage or ink interruption during the printing process. Moreover, the alignment mark ink storage opening can also play a buffering and ink uniformity role, improving the printing quality of the alignment mark points.

[0088] In some embodiments of the present invention, the orthographic projection of the alignment mark opening 12 on the ink storage layer is located within the alignment mark ink storage opening. Compared to the cross-sectional area of ​​the alignment mark opening 12 perpendicular to the thickness direction, the cross-sectional area of ​​the alignment mark ink storage opening perpendicular to the thickness direction can be appropriately increased to improve the ink replenishment capacity and ensure stable ink supply during the printing process.

[0089] In some embodiments of the present invention, the ink storage layer includes a grid line ink storage opening that penetrates the ink storage layer, the grid line ink storage opening is correspondingly disposed with the grid line opening 11, and the grid line ink storage opening and the grid line opening 11 are connected.

[0090] The grid line ink storage opening is used to store ink to continuously replenish ink to the grid line opening 11, avoiding ink shortages or interruptions during the printing process. In addition, the grid line ink storage opening can also play a role in buffering and ink uniformity, improving the printing quality of the grid lines.

[0091] In some embodiments of the present invention, the orthogonal projection of the grid line opening 11 onto the ink storage layer is located within the grid line ink storage opening. Compared to the cross-sectional area of ​​the grid line opening 11 perpendicular to the thickness direction, the cross-sectional area of ​​the grid line ink storage opening perpendicular to the thickness direction can be appropriately increased to improve the ink replenishment capacity and ensure stable ink supply during the printing process.

[0092] In summary, the screen structure disclosed in this embodiment of the invention, by providing a filamentary structure 2 corresponding to the alignment mark opening 12 on the squeegee side of the screen body 1, with the wire diameter of the metal wires 21 in the filamentary structure 2 within the target wire diameter range and the hollow portion 22 between the metal wires 21 within the target size range, alleviates the periodic stress concentration in the alignment mark area, thereby reducing or even avoiding phenomena such as ink leakage in the alignment mark area, improving printing defects, and enhancing the electrical performance of the solar cell. Furthermore, the screen body 1 is a rigid screen body, and the grid opening 11 is fully open, enabling the printing of finer grid lines, reducing the light-blocking area of ​​the solar cell, improving the light absorption capacity of the solar cell, enhancing conversion efficiency, and using less ink, thus reducing the cost of the solar cell.

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0094] The above embodiments are merely illustrative of several implementation methods described in detail, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this specification, and these all fall within the protection scope of this specification. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A screen printing structure, characterized in that, include: The screen printing body has a squeegee side and a printing side that are arranged opposite to each other, and the screen printing body includes an alignment mark opening that penetrates the screen printing body; A filamentous structure is provided on the squeegee side of the screen body and is correspondingly provided with the alignment mark opening. The filamentous structure includes multiple metal wires, and multiple hollow portions are provided between the multiple metal wires and connected to the alignment mark opening. The diameter of the metal wire is within the target diameter range, and the size of the hollowed-out portion is within the target size range.

2. The screen printing structure according to claim 1, characterized in that, The target wire diameter ranges from 0.5 μm to 4 μm.

3. The screen printing structure according to claim 1, characterized in that, The plurality of metal wires are spaced apart, and the hollowed-out portion is located between two adjacent metal wires.

4. The screen printing structure according to claim 3, characterized in that, The dimensions of the cutout include the width of the cutout, which is equal to the distance between two adjacent metal wires, and the target size range is 1.5μm to 10μm.

5. The screen printing structure according to claim 1, characterized in that, The plurality of metal wires include a plurality of first metal wires spaced apart and a plurality of second metal wires spaced apart. The plurality of first metal wires and the plurality of second metal wires are intersected and arranged in a hollowed-out mesh structure. The hollowed-out portion includes the hollowed-out mesh in the hollowed-out mesh structure.

6. The screen printing structure according to claim 5, characterized in that, The dimensions of the cutout portion include the diagonal dimension of the cutout mesh, and the target size range is... μm~ μm.

7. The screen printing structure according to claim 1, characterized in that, The screen printing body also includes a grid opening that penetrates the screen printing body; The main body of the screen is a rigid screen body, and the grid openings are fully open; and / or, The alignment mark opening is tangential to the gate line opening.

8. The screen printing structure according to any one of claims 1-7, characterized in that, The screen printing body includes a first functional layer and at least one second functional layer that are sequentially stacked between the printing side and the squeegee side; The hardness of the first functional layer is less than that of the battery cell, and the hardness of the second functional layer is greater than that of the first functional layer.

9. The screen printing structure according to claim 8, characterized in that, The Mohs hardness of the first functional layer is 1 to 4.

5.

10. The screen printing structure according to claim 8, characterized in that, The material of the first functional layer includes at least one of the following: a Bi-Sn binary alloy system, a Bi-Sn-Al ternary alloy system, a Bi-Sn-Al-Zn quaternary alloy system, and a conductive polymer material; and / or, The material of the second functional layer includes at least one of the Ni-W binary alloy system and nickel alloy.

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