Steel stencil used for printing and manufacturing method therefor

Abstract

A steel stencil used for printing and a manufacturing method therefor, wherein the steel stencil comprises a metal layer (100) and at least two cushion layers (200) that are sequentially stacked, and the hardness of each cushion layer is lower than that of a substrate; a plurality of first fine-grid apertures (110) run through the metal layer; and a plurality of second fine-grid apertures (210) run through each cushion layer, the plurality of second fine-grid apertures on different layers are arranged in one-to-one correspondence, and the plurality of first fine-grid apertures and the plurality of second fine-grid apertures are arranged in one-to-one correspondence. The steel stencil can prevent partial indentation or microcracks of an OTO layer on the surface of a silicon wafer during printing.

Description

Steel plates for printing and their preparation methods

[0001] This application claims priority to Chinese Patent Application No. 202510309821.1, filed with the Chinese Patent Office on March 17, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery printing plate technology, for example to a printing steel plate and a method for preparing it. Background Technology

[0003] Screen printing stencils are an important tool for printing solar cell electrodes. Screen printing stencil manufacturers have successively launched knotless stencils. With the development of photovoltaics, the screen printing stencils in related technologies can no longer meet the requirements of extremely fine line width and grid flatness. The development of screen printing stencils was once sluggish. As a result, fully open steel plates appeared, which can meet the requirements of extremely fine line width and grid flatness at the same time.

[0004] To prevent the stencil from directly contacting the silicon wafer and damaging the OTO layer on the surface of the heterojunction silicon wafer (OTO is a multilayer transparent conductive oxide structure composed of stacked indium tin oxide (ITO), zinc tin oxide (ZTO), and indium tin oxide (ITO), which would affect photoelectric conversion efficiency), a soft coating, such as a polyimide film, is often placed on the bottom of the stencil. However, after prolonged use, wear can cause the stencil to be exposed in parts of the soft coating, making it easy for the surface of the substrate to come into direct contact with the stencil. This can result in partial damage or microcracks to the OTO layer on the substrate surface, leading to a decrease in the electrical performance of the solar cell and affecting its efficiency. Summary of the Invention

[0005] This application provides a printing steel plate and its preparation method to avoid partial damage or microcracks to the OTO layer on the silicon wafer surface during the printing process, thereby ensuring the power generation performance of the solar cell.

[0006] The following technical solution is adopted in this application:

[0007] A printing plate includes sequentially stacked metal layers and at least two buffer layers, wherein the hardness of each buffer layer is set to be lower than the hardness of the substrate.

[0008] A plurality of first fine grid holes are provided through the metal layer;

[0009] Each buffer layer is provided with multiple second fine grid holes, and the multiple second fine grid holes on different layers are arranged in a one-to-one correspondence, and the multiple first fine grid holes are arranged in a one-to-one correspondence with the multiple second fine grid holes.

[0010] In one embodiment, the buffer layer adjacent to the metal layer is made of metal.

[0011] In one embodiment, the buffer layer is made of a nickel-cobalt alloy.

[0012] In one embodiment, the buffer layer adjacent to the substrate is made of a non-metallic material.

[0013] In one embodiment, the metal layer is provided with multiple layers, and multiple first fine grid holes on different layers are provided in a one-to-one correspondence, and the hole wall of any first fine grid hole can be combined with the adjacent metal layer or buffer layer below to form a storage tank.

[0014] A method for preparing a printing steel plate, comprising:

[0015] A base buffer layer is disposed on a substrate, and other buffer layers and metal layers are sequentially stacked on the base buffer layer in a direction away from the substrate.

[0016] The top of the basic buffer layer is divided into a processing area and a non-processing area, and the non-processing area corresponds to the graphic area of ​​the steel plate.

[0017] The remaining buffer layer and metal layer are processed layer by layer in the processing area to form a second fine grid hole and a first fine grid hole in the non-processing area;

[0018] Separate the substrate from the base buffer layer;

[0019] The second fine grid hole is machined on the base buffer layer.

[0020] In one embodiment, dividing the top of the base buffer layer into a processed area and a non-processed area includes:

[0021] A dry film is attached to the base buffer layer, and the portion corresponding to the patterned area is exposed.

[0022] Remove the dry film from the unexposed areas to form the processing area.

[0023] In one embodiment, the base buffer layer is made of a non-metallic material;

[0024] The preparation method further includes attaching a conductive layer onto the basic buffer layer.

[0025] In one embodiment, the step of processing the remaining buffer layers and metal layers layer by layer in the processing area includes:

[0026] The remaining buffer layers and metal layers are processed by electroplating, evaporation plating or electroforming.

[0027] In one embodiment, processing the second fine gate aperture on the base buffer layer includes:

[0028] Based on the position of the first or second fine grid hole within the graphic area, a laser is used to drill holes in the base buffer layer to obtain the second fine grid hole located on the base buffer layer. Attached Figure Description

[0029] Figure 1 is a cross-sectional view of the steel plate in an embodiment of this application;

[0030] Figure 2 is a flowchart of the steel plate preparation method in an embodiment of this application.

[0031] In the picture:

[0032] 100, Metal layer; 110, First fine gate aperture; 200, Buffer layer; 210, Second fine gate aperture;

[0033] 11. First metal layer; 12. Second metal layer;

[0034] 21. Basic buffer layer; 22. First buffer layer; 23. Second buffer layer. Detailed Implementation

[0035] The present application will now be described in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit its scope. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present application, not the entire structure.

[0036] In the description of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0039] This embodiment proposes a printing steel plate, which includes a metal layer 100 stacked sequentially and at least two buffer layers 200. The buffer layer 200 that is in direct contact with the substrate is named the basic buffer layer 21, and the remaining buffer layers 200 are collectively named the remaining buffer layers 200. The hardness of each buffer layer 200 is lower than that of the substrate. A plurality of first fine grid holes 110 are provided through the metal layer 100. A plurality of second fine grid holes 210 are provided through the buffer layer 200. The plurality of second fine grid holes 210 on different layers are arranged one-to-one, and the plurality of first fine grid holes 110 and the plurality of second fine grid holes 210 are arranged one-to-one.

[0040] It is understandable that the multiple first fine grid holes 110 penetrating the metal layer 100 can form the graphic area of ​​the steel plate, and the second fine grid holes 210 on the buffer layer 200 can form a feeding channel to prevent the paste from falling. When the base buffer layer 21 is worn, the buffer layer 200 above it can contact the substrate. Since the hardness of each buffer layer 200 is lower than that of the substrate, it can prevent the OTO layer on the surface of the substrate from being damaged or cracked during the printing process, thereby reducing the probability of defective products and ensuring the power generation performance of the solar cell. In addition, the setting of multiple buffer layers 200 can reduce the number of times the steel plate needs to be replaced due to wear of the base buffer layer 21, thereby ensuring the smoothness of the solar cell printing process and improving the quality and stability of the solar cell in mass production.

[0041] For example, when the Mohs hardness of the substrate is 7-8 HM, the Mohs hardness of each buffer layer 200 is 1-4 HM. In some other feasible embodiments, the Mohs hardness of each buffer layer 200 can be determined according to the Mohs hardness of the substrate, and no specific limitation is made here.

[0042] In one embodiment, the buffer layer 200 adjacent to the metal layer 100 is made of a metal. It is understood that the metal layer 100 is made of a metal such as nickel or a nickel alloy. The bonding strength between metal materials is greater than the bonding strength between non-metal materials, thereby improving the strength and stability of the steel plate. The buffer layer 200 is made of a nickel-cobalt alloy. In some other feasible embodiments, the buffer layer 200 may also be made of other metal materials, which will not be elaborated here.

[0043] Furthermore, the buffer layer 200 adjacent to the substrate is made of a non-metallic material. That is, the base buffer layer 21 is made of a non-metallic material. It is understandable that silicon is often used as the substrate in the current solar cell manufacturing process. Since silicon is a brittle material and easily breaks, the base buffer layer 21 in contact with the silicon is made of a non-metallic material. Non-metallic materials can reduce vibration transmission when the printing blade contacts the steel plate and can elastically absorb mechanical impact, preventing stress concentration from being transmitted to the silicon wafer. The base buffer layer 21 can be made of polyimide; in some other feasible embodiments, it can also be made of other non-metallic materials, which will not be elaborated here.

[0044] For example, the buffer layer 200 is provided with three layers, from bottom to top: a base buffer layer 21, a first buffer layer 22, and a second buffer layer 23. The first buffer layer 22 and the second buffer layer 23 are the other buffer layers 200. The base buffer layer 21 is in contact with the substrate, and the second buffer layer 23 is connected to the metal layer 100.

[0045] In this embodiment, the metal layer 100 is provided with multiple layers, and multiple first fine grid holes 110 on different layers are arranged in a one-to-one correspondence. The hole wall of any first fine grid hole 110 can be combined with the adjacent metal layer 100 or buffer layer 200 below to form a storage tank. It can be understood that the setting of the storage tank facilitates the storage of paste during printing, thereby ensuring the continuity of paste in the feeding process and thus ensuring printing quality.

[0046] For example, the metal layer 100 has two layers, named sequentially from bottom to top as a first metal layer 11 and a second metal layer 12. The diameter of the first fine grid hole 110 in the first metal layer 11 is the same as the diameter of the second fine grid hole 210, and the diameter of the first fine grid hole 110 in the second metal layer 12 is larger than the diameter of the second fine grid hole 210. That is, the hole wall of the first fine grid hole 110 in the second metal layer 12 and the first metal layer 11 form a storage tank. The first fine grid hole 110 in the first metal layer 11 is located at the bottom of the storage tank. The diameter of the first fine grid hole 110 can be expanded outward by 10-200 μm on one side compared to the diameter of the second fine grid hole 210 to form the storage tank.

[0047] This embodiment also proposes a method for preparing the steel plate as described above, which includes:

[0048] S1: A base buffer layer 21 is disposed on the substrate, and other buffer layers 200 and metal layers 100 are sequentially stacked on the base buffer layer 21 away from the substrate; wherein, the base buffer layer 21 can be made of metal or non-metal.

[0049] S2: Divide the top of the base buffer layer 21 into a processing area and a non-processing area, with the non-processing area corresponding to the graphic area of ​​the steel plate.

[0050] S3: Process the remaining buffer layer 200 and metal layer 100 layer by layer in the processing area to form the second fine grid hole 210 and the first fine grid hole 110 in the non-processing area.

[0051] S4: Separate the substrate from the base buffer layer 21;

[0052] S5: Machining a second fine grid hole 210 on the base buffer layer 21.

[0053] It is understandable that, based on the fact that when the processing area is processing the remaining buffer layer 200 and the metal layer 100, the first fine grid hole 110 or the second fine grid hole 210 can be directly formed in the non-processing area, so that there is no need to make additional holes in the metal layer 100 after the steel plate is processed, thereby improving the strength of the steel plate.

[0054] Because a single metal layer 100 is subjected to tension in multiple directions, a louvered effect is prone to appear on its surface, leading to abnormal printing appearance on the substrate and increasing the defect rate of the solar cell. Therefore, in this embodiment, the metal layer 100 is processed into multiple layers. Multiple metal layers 100 can further improve the rigidity of the steel plate, thereby reducing the deformation of any one metal layer 100. The metal layer 100 can be two layers.

[0055] In step S2, the top of the base buffer layer 21 is divided into a processing area and a non-processing area, including:

[0056] S21: A dry film is attached to the base buffer layer 21, and the part corresponding to the pattern area is exposed.

[0057] S22: Remove the dry film from the unexposed areas to form the processing area.

[0058] Understandably, the dry film, as a photoresist, is attached to the base buffer layer 21. After the dry film in the graphic area is exposed, the dry film in the graphic area can be hardened. That is, the dry film in the non-processing area is hardened, while the dry film in the processing area remains unchanged. Then the dry film in the processing area is removed to expose the window that is easy to process. After the entire steel plate is processed, the hardened dry film is removed by alkaline solution to ensure that the surface of the steel plate is clean and to avoid contamination or performance interference in subsequent use.

[0059] In step S3, processing the remaining buffer layer 200 and metal layer 100 layer by layer in the processing area includes processing the remaining buffer layer 200 and metal layer 100 by means of electroplating, evaporation plating, or electroforming. It is understood that using methods such as electroplating, evaporation plating, or electroforming can ensure the accuracy of the first fine grid hole 110 and the second fine grid hole 210 during the forming process, thereby ensuring the accuracy of the slurry feeding.

[0060] Compared to processing the remaining buffer layer 200 and metal layer 100 as a single piece, the layer-by-layer processing method has higher forming efficiency and is easier to produce.

[0061] When the base buffer layer 21 is made of a non-metallic material, the non-metallic material can reduce the vibration transmission when the printing blade contacts the steel plate and can elastically absorb mechanical shock, avoiding stress concentration transmission to the silicon wafer. To facilitate the processing of other buffer layers 200 on the base buffer layer 21, the preparation method further includes attaching a conductive layer to the base buffer layer 21. Under the action of the conductive layer, a conductive substrate can be provided for the subsequent processing of other buffer layers 200 by electroforming or electroplating. The thickness of the conductive layer is 50-100nm. The extremely thin conductive layer can maintain the conductivity requirements without significantly increasing the overall thickness.

[0062] In step S5, processing the second fine gate hole 210 on the base buffer layer 21 includes: drilling holes in the base buffer layer 21 using a laser according to the position of the first fine gate hole 110 or the second fine gate hole 210 within the pattern area to obtain the second fine gate hole 210 on the base buffer layer 21. It is understood that after separating the substrate from the base buffer layer 21, the base buffer layer 21 can block the second fine gate holes 210 on the remaining buffer layers 200. Therefore, it is necessary to drill holes in the base buffer layer 21 to ensure the unobstructed flow of the entire feeding channel.

Claims

1. A printing plate comprising sequentially stacked metal layers (100) and at least two buffer layers (200), wherein, The hardness of each of the buffer layers (200) is set to be lower than that of the substrate; A plurality of first fine grid holes (110) are provided through the metal layer (100); Each buffer layer (200) is provided with a plurality of second fine grid holes (210), and the plurality of second fine grid holes (210) on different layers are provided in a one-to-one correspondence, and the plurality of first fine grid holes (110) are provided in a one-to-one correspondence with the plurality of second fine grid holes (210).

2. The printing plate according to claim 1, wherein, The buffer layer (200) adjacent to the metal layer (100) is made of metal.

3. The printing plate according to claim 1, wherein, The buffer layer (200) is made of nickel-cobalt alloy.

4. The printing plate according to claim 1, wherein, The buffer layer (200) adjacent to the substrate is made of a non-metallic material.

5. The printing plate according to claim 1, wherein, The metal layer (100) is provided with multiple layers, and multiple first fine grid holes (110) on different layers are provided one-to-one, and the hole wall of any first fine grid hole (110) can be combined with the adjacent metal layer (100) or buffer layer (200) below to form a storage tank.

6. A method for preparing a printing steel plate, used to prepare the steel plate as described in any one of claims 1-5, comprising: A base buffer layer (21) is disposed on the substrate, and other buffer layers (200) and metal layers (100) are sequentially stacked on the base buffer layer (21) away from the substrate. The top of the basic buffer layer (21) is divided into a processing area and a non-processing area, the non-processing area corresponding to the graphic area of ​​the steel plate; The remaining buffer layer (200) and the metal layer (100) are processed layer by layer in the processing area to form a second fine grid hole (210) and a first fine grid hole (110) in the non-processing area. Separate the substrate from the base buffer layer (21); The second fine grid hole (210) is machined on the base buffer layer (21).

7. The method for preparing a printing steel plate according to claim 6, wherein, The division of the top of the base buffer layer (21) into a processing area and a non-processing area includes: A dry film is attached to the base buffer layer (21), and the portion corresponding to the pattern area is exposed. Remove the dry film from the unexposed areas to form the processing area.

8. The method for preparing a printing steel plate according to claim 6, wherein, The basic buffer layer (21) is made of a non-metallic material; The preparation method further includes attaching a conductive layer onto the basic buffer layer (21).

9. The method for preparing a printing steel plate according to claim 6, wherein, The step of processing the remaining buffer layer (200) and the metal layer (100) layer by layer in the processing area includes: The remaining buffer layer (200) and the metal layer (100) are processed by electroplating, evaporation plating or electroforming.

10. The method for preparing a printing steel plate according to claim 6, wherein, The process of machining the second fine gate hole (210) on the base buffer layer (21) includes: Based on the position of the first fine grid hole (110) or the second fine grid hole (210) within the graphic area, a laser is used to drill holes in the base buffer layer (21) to obtain the second fine grid hole (210) on the base buffer layer (21).

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