Printing plate

Abstract

The utility model discloses a printing plate which comprises a metal film (3), the metal film (3) is provided with a grid line opening area and protection areas (3b), a gap exists between every two adjacent protection areas (3b) to form the grid line opening area, and the grid line opening area comprises a plurality of grid line openings (3a) which are arranged at intervals. The grid line opening (3a) comprises a first opening (3a1) and a second opening (3a2) which are oppositely arranged in the thickness direction of the metal film (3), the grid line opening is used for enabling metal slurry flowing in from the first opening to flow out from the second opening, and the opening width of the first opening (3a1) is smaller than that of the second opening (3a2).

Description

Technical Field

[0001] This utility model relates to the field of solar cell technology, specifically to a printing plate. Background Technology

[0002] Screen printing is currently the mainstream technology for manufacturing metal grid electrodes in solar cells. However, as the cost of solar cells decreases, the width of the printed grid lines is also shrinking. In the past decade, the printing width of solar cell electrode grid lines has decreased from around 100 micrometers to below 20 micrometers. Simultaneously, with the reduction in line width, it is necessary to optimize the grid line cross-sectional structure to reduce internal resistance. Conventional screen printing line shapes mainly depend on the printing characteristics of the paste and printing parameters; the mesh layer does not adjust the cross-sectional shape of the printed grid lines.

[0003] Therefore, designing and developing a printing plate structure that refines the grid line width while optimizing the cross-sectional shape of the electrode grid lines, reducing internal resistance, and increasing light absorption to improve the conversion efficiency of solar cells is an urgent problem to be solved in this field. Utility Model Content

[0004] This invention aims to address one of the technical problems in related technologies to a certain extent. Therefore, this invention provides a printing plate and a solar cell.

[0005] To achieve the above objectives, this utility model discloses a printing plate, which includes an outer frame and a metal film. The metal film is provided with a grid line opening area and a protection area. There is a gap between two adjacent protection areas to form the grid line opening area. The grid line opening area includes a plurality of grid line openings arranged at intervals. The grid line openings include a first opening and a second opening arranged opposite to each other along the thickness direction of the metal film. The grid line openings are used to allow metal paste flowing in from the first opening to flow out from the second opening. The opening width of the first opening is smaller than the opening width of the second opening.

[0006] Furthermore, the absolute value of the difference between the opening width of the first opening and the opening width of the second opening is between 3 micrometers and 30 micrometers.

[0007] Furthermore, the opening width of the first opening is between 2 μm and 10 μm, and the opening width of the second opening is between 5 μm and 50 μm.

[0008] Furthermore, the multiple gate openings are arranged in multiple rows and columns.

[0009] Furthermore, the thickness of the metal film is between 10 μm and 100 μm.

[0010] Furthermore, the printing plate also includes an organic film, which is stacked on the surface of the metal film where the second opening is formed. The organic film has an opening area that corresponds to the second opening.

[0011] Furthermore, the printing plate also includes an outer frame and a mesh fabric, and the organic film and the metal film are fixed to the outer frame by the mesh fabric at a set tension.

[0012] Furthermore, the set tension is between 8 N / cm and 30 N / cm.

[0013] Furthermore, there is a connection area between the metal film and the mesh fabric.

[0014] Furthermore, the metal film includes one of an iron alloy film, a nickel alloy film, and a titanium alloy film.

[0015] The printing plate structure designed in this utility model can adjust and optimize the morphology of the printing grid lines while reducing the printing line width, forming grid lines with triangular or trapezoidal cross-sections. This results in grid lines with a larger bottom contact area, reducing contact resistance. Compared with traditional grid lines, although the grid lines in this application with triangular or trapezoidal cross-sections still have a larger shading width, the light blocked by the grid lines is reflected onto the inclined surface of the grid lines and enters the effective area of ​​the solar cell, allowing the solar cell to absorb more light energy, thereby reducing shading loss and achieving higher conversion efficiency.

[0016] The printing plate of this application, by employing a fully open structure, can further refine the grid lines. The open area is free from screen obstruction, resulting in smoother printing of the grid lines, narrower linewidths, and a more uniform and stable morphology. The printing plate utilizes a metal film with a certain thickness to optimize the shape of the grid line openings. The openings are configured as a first opening and a second opening with different widths; the first opening is narrower than the second opening. This allows the metal paste to flow in through the narrower first opening. Upon encountering the trapezoidal, gradually widening opening structure, the extruded metal paste flows along the metal film wall between the first and second openings, briefly filling the trapezoidal opening structure, and finally flowing out from the second opening to form triangular grid lines. Furthermore, the printing plate structure of this application allows for further adjustment of the grid line morphology by adjusting the dimensions between the first and second openings, i.e., the trapezoidal angle. This allows for adjustment of the width, height, and angle of the triangular grid lines, thereby meeting the performance requirements of solar cells with different specifications.

[0017] The improved solar cell grid structure of this application ensures a lower grid contact resistance while increasing light intake and reducing shading loss.

[0018] These features and advantages of this utility model will be disclosed in detail in the following specific embodiments and accompanying drawings. The preferred embodiments or means of this utility model will be shown in detail in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of this utility model. In addition, each of these features, elements and components appearing in the following text and drawings is multiple and is labeled with different symbols or numbers for convenience, but all represent parts with the same or similar structure or function. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings:

[0020] Figure 1 A schematic diagram of one embodiment of the printing plate provided by this utility model;

[0021] Figure 2 A schematic diagram of another embodiment of the printing plate provided by this utility model;

[0022] Figure 3 This is a partially enlarged schematic diagram of the grid openings of the printing plate provided by this utility model;

[0023] Figure 4 A schematic diagram illustrating one embodiment of the printing plate forming grid lines provided by this utility model.

[0024] Figure 5 A schematic diagram illustrating one embodiment of the grid structure of the solar cell provided by this utility model;

[0025] Figure 6 A magnified cross-sectional photograph of one embodiment of the printing plate provided in Embodiment 1 of this application;

[0026] Figure 7 This is a outline diagram of one embodiment of the grid lines of the solar cell provided in Embodiment 1 of this application.

[0027] Explanation of reference numerals in the attached figures

[0028] 1: Outer frame 2: Mesh fabric

[0029] 3: Metal membrane 4: Organic membrane

[0030] 5: Metal grid lines; 6: Base of solar cell

[0031] 3a: Fence opening 3b: Protected area

[0032] 3a1: First opening; 3a2: Second opening Detailed Implementation

[0033] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain this utility model and should not be construed as limiting it.

[0034] The terms "an embodiment," "example," or "trademark" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this application. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0035] The pattern area of ​​a screen printing stencil typically consists of a mesh and an organic film. The pattern of the metal grid lines is determined by the opening pattern on the organic film. Currently, there are two main types of organic films: photosensitive emulsion and PI film coated with an adhesive layer. For photosensitive emulsion, the pattern is created through exposure and development; for PI film coated with an adhesive layer, the pattern is created using laser encapsulation. During the printing process, the ink first passes through the mesh layer, then through the opening pattern on the organic film, ultimately forming the target pattern on the substrate. With increasing demands for ink conservation, the total thickness of the screen is continuously decreasing, with mainstream mesh thickness between 10-15 micrometers and organic film thickness between 2-5 micrometers. The total screen thickness is primarily determined by the mesh layer thickness, and the mesh layer does not shape the cross-sectional shape of the printed grid lines. Therefore, the line shape in conventional mesh screen printing mainly depends on the ink printing characteristics and printing parameters.

[0036] For solar cells, the shape of the electrode grid lines has a significant impact on power generation performance. For example, the grid line width affects the solar cell's light-receiving area, and the cross-sectional area of ​​the grid lines affects the solar cell's internal resistance. Therefore, optimizing the shape of the electrode grid lines is an important way to improve the conversion efficiency of solar cells. Over the past decade, the printed width of solar cell electrode grid lines has decreased from around 100 micrometers to below 20 micrometers, playing a crucial role in improving solar cell conversion efficiency. With the current printed line width already below 20 micrometers, further reducing the printed line width has become significantly more difficult. However, through optimized design of the printed line shape, it is possible to improve the solar cell conversion efficiency without reducing the printed line width.

[0037] To address the aforementioned problems, this utility model discloses a printing plate comprising a metal film 3. The metal film 3 is provided with a grid line opening area and a protection area 3b. There is a gap between two adjacent protection areas 3b to form the grid line opening area. The grid line opening area includes multiple grid line openings 3a arranged at intervals. Each grid line opening 3a includes a first opening 3a1 and a second opening 3a2 arranged opposite to each other along the thickness direction of the metal film. The grid line openings 3a are used to allow metal paste flowing in from the first opening 3a1 to flow out from the second opening 3a2. The opening width of the first opening 3a1 is smaller than the opening width of the second opening 3a2. This dimensional setting causes the cross-section of the grid line opening 3a to form a trapezoidal structure.

[0038] The printing plate of this application, by adopting a fully open structure, can further refine the grid lines. The open area is free from screen obstruction, resulting in smoother printed grid lines with smaller line widths and more uniform and stable morphology. The printing plate of this application utilizes a metal film with a certain thickness to optimize the shape of the grid line openings. The openings are set as a first opening and a second opening with different widths; the first opening is narrower than the second opening. This allows the metal paste to flow in from the narrower first opening. Upon encountering the trapezoidal, gradually widening opening structure, the extruded metal paste flows along the metal film wall between the first and second openings, briefly filling the trapezoidal opening structure, and finally flowing out from the second opening to form triangular grid lines.

[0039] The improved solar cell grid structure of this application ensures a lower grid contact resistance while increasing light intake and reducing shading loss.

[0040] This application does not impose special limitations on the difference in width between the first and second openings, as long as the first opening is smaller than the second opening. Preferably, to form triangular grid lines with larger angles, the absolute value of the difference between the widths of the first and second openings is between 3 and 30 micrometers. If the difference is too small, the angle of the triangle is too small, and the inclined surface cannot reflect more light into the solar cell, resulting in a decrease in conversion efficiency. Furthermore, the printing plate structure of this application can further adjust the grid line morphology by adjusting the size between the first and second openings, i.e., the trapezoidal angle. This allows for adjustment of the width, height, and angle of the triangular grid lines, thereby meeting the performance requirements of solar cells with different specifications.

[0041] This application does not specifically limit the opening width of the first and second openings. The width of the first opening affects the extrusion of the metal paste; if it is too narrow, the metal paste may be difficult to scrape out. However, if the first opening is too wide, an effective triangular interface grid line cannot be formed. Preferably, the opening width of the first opening 3a1 is between 2 μm and 10 μm. The width of the second opening affects the width of the base of the triangle, thereby affecting the shading area. To ensure sufficient grid line width without obstructing the battery too much, preferably, the opening width of the second opening 3a2 is between 5 μm and 50 μm.

[0042] In order to form an effective triangular grid structure, the thickness of the metal film also affects the selection of the size of the first and second openings. If the metal film is too thin, the metal slurry flows into and out of the opening too quickly, which is not enough to fill the trapezoidal grid opening and thus cannot form a triangular grid. Preferably, the thickness of the metal film is between 10 μm and 100 μm.

[0043] This application does not impose any special limitation on the arrangement of the gate openings; the gate openings can be multiple complete gate lines arranged at intervals, such as... Figure 2 As shown, it can also be that multiple sub-grid lines are segmented to form a single grid line, such as... Figure 1 As shown.

[0044] To ensure greater stability and resistance to deformation of the printing grid lines on a fully open printing plate, it is preferable that the multiple grid line openings are arranged in multiple rows and columns, such as... Figure 1 As shown, this regularly arranged distribution method is beneficial to the printing operation. The printing plate with multiple discontinuous grid lines can be printed in combination with the printing plate with connecting node openings to form a complete and continuous sub-grid line. In the process of printing connecting wires on the steel plate, the design of this multi-segment short-distance opening pattern solves the printing deformation problem of long-distance opening patterns on the steel plate, and makes the steel plate printing process more stable. It can produce grid lines with uniform width, consistent morphology, and a larger aspect ratio, which is beneficial to the reliability of solar cells.

[0045] To facilitate precise dimensional processing of the first and second openings of the metal film, the gate openings of this application are formed by at least one of laser cutting, etching, and electroforming.

[0046] When printing grid lines using the printing plate of this application, it should be noted that the distance between the printing plate and the solar cell affects the morphology of the metal grid lines. To ensure the metal paste can pass through the trapezoidal grid line openings and its shape can be quickly fixed, the printing plate needs to be positioned close to the bottom of the solar cell. When the squeegee applies the metal paste, it generates scraping pressure, causing the printing plate to deform. To protect the surface of the underlying solar cell from damage by the deformed printing plate, the printing plate also includes an organic film 4, such as... Figure 1 and Figure 2 As shown, the organic film is stacked on the surface of the metal film where the second opening is formed. Preferably, the organic film is an organic material with an elastic modulus not higher than 10 GPa and a Shore hardness not higher than 100, and is manufactured by lamination or coating. The organic film is laminated to the surface of the metal film where the second opening 3a2 is formed, and the organic film has an opening area, which corresponds to the second opening 3a2.

[0047] To ensure printing stability, the organic film and the metal film are fixed to the outer frame 1 under a set tension. Preferably, the set tension is between 8 N / cm and 30 N / cm. As an optional implementation, the printing plate also includes a mesh fabric 2. The organic film 4 and the metal film 3 are fixed to the outer frame 1 by the mesh fabric 2 under a set tension. The outer frame 1 is generally a rigid mesh frame.

[0048] In order to prevent the tension of the mesh from deforming the opening pattern on the metal membrane, as an optional implementation, a connection area is provided between the metal membrane and the mesh. This connection area can buffer the stress of the mesh on the metal membrane and prevent severe deformation of the opening of the metal membrane.

[0049] This invention does not impose any special limitations on the material of the metal film. In order to facilitate the processing of the opening structure, metals with good processing properties and certain strength and toughness are generally used to improve the printing plate life. Preferably, the metal film includes one of iron alloy film, nickel alloy film and titanium alloy film.

[0050] The grid lines of the solar cell are formed using the printing plate of this application. They can be applied to the front and / or back electrodes, and also to the main grid and / or sub-grids. The printing plate structure designed in this invention can adjust and optimize the morphology of the printed grid lines while reducing the printing linewidth, forming grid lines with triangular or trapezoidal cross-sections. This results in grid lines with a larger bottom contact area, reducing contact resistance. Compared to traditional grid lines, although the grid lines of this application with triangular or trapezoidal cross-sections still have a larger shading width, light blocked by the grid lines is reflected onto the inclined surface of the grid lines and enters the effective area of ​​the solar cell, allowing the solar cell to absorb more light energy, thereby reducing shading loss and achieving higher conversion efficiency.

[0051] For ease of understanding, a schematic diagram of the printing plate forming the solar cell grid lines in this application is shown below. Figure 4 and Figure 5 As shown, specifically, grid lines are printed on at least one surface of the solar cell base 6 using the printing plate of this application. It should be noted that the distance between the printing plate and the solar cell will affect the morphology of the metal grid lines 5. In order for the metal paste to pass through the trapezoidal grid line openings and for the shape of the paste to be quickly fixed and formed, the printing plate needs to be set at a distance close to the surface of the solar cell base 6 to print the grid lines, or direct contact printing can be used.

[0052] The present application will be further explained below with reference to embodiments.

[0053] Example 1

[0054] The printing plate of this application is used to print grid lines on at least one surface of a solar cell.

[0055] Test case

[0056] The cross-section of the printing plate of this application was magnified and photographed using an optical microscope, such as... Figure 6 As shown, the width of the first opening is between 6 and 7 micrometers, and the width of the second opening is between 13 and 15 micrometers. The contour scanning analysis of the solar cell grid lines formed by the printing plate of this application was performed using an Olympus DSX-1000 device, as shown... Figure 7 As shown, the bottom width of the printed triangular grid lines is approximately 12 micrometers, and the height is approximately 6 micrometers.

[0057] The above are merely specific embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Those skilled in the art should understand that this utility model includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of this utility model will be included within the scope of the claims.

Claims

1. A printing plate, said printing plate comprising a metal film (3), characterized in that, The metal film (3) is provided with a grid opening area and a protection area (3b). There is a gap between two adjacent protection areas (3b) to form the grid opening area. The grid opening area includes a plurality of grid openings (3a) arranged at intervals. The grid opening (3a) includes a first opening (3a1) and a second opening (3a2) arranged opposite to each other along the thickness direction of the metal film (3). The grid opening is used to allow metal slurry flowing in from the first opening to flow out from the second opening. The opening width of the first opening (3a1) is smaller than the opening width of the second opening (3a2).

2. The printing plate according to claim 1, characterized in that, The absolute value of the difference between the opening width of the first opening and the opening width of the second opening is between 3 micrometers and 30 micrometers.

3. The printing plate according to claim 2, characterized in that, The opening width of the first opening is between 2 μm and 10 μm, and the opening width of the second opening is between 5 μm and 50 μm.

4. The printing plate according to claim 1, characterized in that, The multiple gate openings are arranged in multiple rows and columns.

5. The printing plate according to claim 1, characterized in that, The thickness of the metal film is between 10 μm and 100 μm.

6. The printing plate according to any one of claims 1 to 5, characterized in that, The printing plate also includes an organic film, which is stacked on the surface of the metal film where the second opening is formed. The organic film has an opening area that corresponds to the second opening.

7. The printing plate according to claim 6, characterized in that, The printing plate also includes an outer frame and a mesh fabric, and the organic film and the metal film are fixed to the outer frame by the mesh fabric with a set tension.

8. The printing plate according to claim 7, characterized in that, The set tension is between 8 N / cm and 30 N / cm.

9. The printing plate according to claim 7, characterized in that, There is a connection area between the metal film and the mesh fabric.

10. The printing plate according to any one of claims 1 to 5, characterized in that, The metal film includes one of iron alloy film, nickel alloy film and titanium alloy film.

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