Solar photovoltaic cell gradual change staggered grid printing screen

Abstract

The invention discloses a solar photovoltaic cell gradual change staggered grid printing screen which comprises a printing plate frame and a printing screen body, the printing screen body is stretched on the printing plate frame through a stretching wire mesh, a plurality of fine grid line grooves and main grid line grooves are formed in the printing screen body and are communicated in a crossed mode, and the fine grid line grooves are communicated with the main grid line grooves in a crossed mode. Two sides of each main grid line groove are respectively provided with a plurality of fine grid line grooves in a staggered manner; the main grid line groove is narrowed from the middle to the two ends, and the narrowing angle alpha of the main grid line groove is 3-6 degrees; the width of the tensioning wire mesh between one side edge of the printing screen and the printing plate frame is L1, the width of the tensioning wire mesh between the other side edge of the printing screen and the printing plate frame is L2, and L1 is equal to (1.5-2.5) L2. The thin grid line grooves on one side of the main grid line grooves are correspondingly located between the two adjacent thin grid line grooves on the other side of the main grid line grooves, and the two groove edges of the main grid line grooves are symmetrically located on the two sides of the groove center line. According to the staggered grid printing screen, the tensioning force of the printing plate can be balanced, and the production cost of solar photovoltaic cells can be reduced.

Description

Technical Field

[0001] The invention relates to a printing template for precise conductive grid lines of solar photovoltaic cells, and in particular to a printing template for conductive grid lines with staggered fine grid line grooves. Background Art

[0002] The front grid lines of solar photovoltaic cells are composed of at least one main grid line and several secondary grid lines (thin grid lines) connected to the main grid lines. The secondary grid lines guide the current generated by the semiconductor material through the photovoltaic effect, and the main grid lines collect the current on each secondary grid line and transmit it through the welding strips welded on them.

[0003] At present, the printing of solar photovoltaic cell grid lines is mostly realized by screen printing technology. In the process of screen printing, the silver paste is printed on the cell silicon wafer by scraping and squeezing the screen printing plate with a scraper. The rebound tension of the screen printing plate is provided by the polyester mesh around the metal mesh. The tension provided by the polyester mesh to the metal mesh has a direct impact on the quality of the printed grid lines. The uneven change of the metal mesh tension during the printing process is prone to distortion of the printed grid line shape and fluctuation of the grid line aspect ratio.

[0004] At the same time, since the secondary grid lines on both sides of the main grid line on the battery cell are currently located on the same straight line, the corresponding secondary grid line printing grooves on the screen printing plate are also located on a straight line. In this way, the two secondary grid line grooves located on the same straight line are easy to pull and tear the two sides of the main grid line groove, causing the main grid line groove to deform and warp. Since the main grid line groove and the secondary grid line groove are cross-connected with each other, the deformation of the main grid line groove will inevitably cause the groove shape of the secondary grid line groove to deform and the groove edge to warp. The deformation and warping of the printed groove directly affect the appearance of the printed grid line corresponding to the groove, as well as the integrity of the grid line pattern, causing slurry splashing, diffusion, uneven thickness and other phenomena at the edges of both sides of the printed groove, resulting in incomplete phenomena such as broken printed grid line electrodes or uneven line height and thickness, which increases the impedance of the electrode pattern and reduces the conversion efficiency of the battery cell. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a solar photovoltaic cell gradient staggered grid printing screen, which can not only effectively balance the tension of the printing plate and avoid deformation of the printing plate groove, but also save a large amount of printing silver paste, thereby effectively reducing the production cost of solar photovoltaic cells.

[0006] In order to solve the above technical problems, the solar photovoltaic cell gradient staggered grid printing screen of the present invention comprises a printing plate frame and a printing screen, the printing screen is stretched on the printing plate frame by a tensioned wire mesh, a plurality of fine grid line grooves and main grid line grooves are arranged on the printing screen, the fine grid line grooves and the main grid line grooves are cross-connected with each other, and a plurality of fine grid line grooves are staggered on both sides of each main grid line groove; the main grid line grooves are narrowed from the middle to both ends, and the narrowing angle of the main grid line grooves is α=3°-6°; the width of the tensioned wire mesh from one side of the printing screen to the printing plate frame is L1, and the width of the tensioned wire mesh from the other side of the printing screen to the printing plate frame is L2, and L1=(1.5-2.5)L2.

[0007] Preferably, the printing screen comprises a metal mesh and a polymer film, the polymer film is coated on the metal mesh, and the fine grid line grooves and the main grid line grooves are arranged on the polymer film.

[0008] Preferably, the printing screen is a metal thin plate, and the fine grid line grooves and the main grid line grooves are arranged on the metal thin plate.

[0009] Preferably, the thin gate line groove on one side of the main gate line groove is correspondingly located between two adjacent thin gate line grooves on the other side of the main gate line groove.

[0010] Preferably, the thin gate line grooves are perpendicular to the main gate line grooves, and a plurality of the thin gate line grooves are parallel to each other.

[0011] Preferably, two groove sides of the main grid line groove are symmetrically arranged on both sides of the groove center line, and the narrowing angle α of the main grid line groove is 3.5°.

[0012] Preferably, the width L1 of one side of the stretched wire mesh is twice the width L2 of the other side.

[0013] Preferably, the fine grid line grooves are arranged along the scraping and pressing moving direction of the scraper, and the side width L1 of the stretched wire mesh is set along the scraping and pressing moving direction of the scraper.

[0014] In the above structure, since a number of fine grid line grooves are staggered on both sides of the main grid line groove, the pulling and tearing of the sides of the grid line groove is avoided, the tensioning force of the tensioned screen is evenly distributed, and the deformation of the main grid line groove and the auxiliary grid line groove caused by such pulling and uneven tension is prevented; when the scraping scraper moves along the length of the printing plate grid groove, the scraping tensioning force acts on the tensioning screen and the screen coating in a staggered and sequential manner as the scraper moves, so the staggered and sequential action of the tensioning force can well avoid the tensile deformation of the printing plate grid, which is beneficial to the precise printing of the battery cell grid line. Furthermore, since the main grid line slot gradually narrows from the middle position to its two ends, the auxiliary grid line current that can be collected at the end of the main grid line slot is small, and the width of the main grid line at the end is narrower, while the auxiliary grid current collected at the middle part of the main grid line is large, and the slot is wider. This not only reduces the shading area of ​​the main grid line on the battery cell, which is beneficial to the increase of the light-receiving area and power generation of the battery cell, but also this structure can effectively save expensive silver paste materials, thereby reducing the production cost of solar cells. Also, because unequal widths of tensioned wire mesh are used on the two perpendicular sides of the printing screen, and the width of the tensioned wire mesh along the scraper scraping path is greater than the screen width on the other side, more elasticity can be generated in the scraping path direction than in the other direction. During the scraping process, the wire groove can be more easily close to the battery substrate under the action of the scraper to achieve precise printing, and the printing steel plate rebounds more quickly and reliably after printing. More importantly, this unequal width tensioned wire mesh setting can also effectively reduce the change of tension force in the width direction of the printing plate wire groove, inhibit and avoid deformation and warping of the wire groove, avoid slurry leakage caused by deformation of the wire groove, and ensure precise printing of fine grid lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The solar photovoltaic cell gradient staggered grid printing screen of the present invention is further described below in conjunction with the accompanying drawings and specific implementations.

[0016] Figure 1 It is a structural schematic diagram of a specific implementation mode of the solar photovoltaic cell gradient staggered grid printing screen of the present invention; Figure 2 yes Figure 1 Cross-sectional view; Figure 3 yes Figure 2 Enlarged view of middle part I; Figure 4 yes Figure 1 Enlarged view of part II.

[0017] In the figure, 1 is a printing plate frame, 2 is a tensioned wire mesh, 3 is a printing screen, 31 is a metal wire mesh, 32 is a polymer film, 4 is a fine grid line groove, and 5 is a main grid line groove. DETAILED DESCRIPTION

[0018] like Figure 1 , Figure 2 and Figure 3 The solar photovoltaic cell gradient staggered grid printing screen shown includes a printing plate frame 1, which is a rectangular frame made of aluminum alloy. A window for stretching the printing screen 3 and the tensioned wire mesh 2 is arranged at the center of the printing plate frame 1. The printing screen 3 includes a metal wire mesh 31 and a polymer film 32 that are adhered to each other, wherein the metal wire mesh 31 is stretched on the bottom side of the printing plate frame 1 through the tensioned wire mesh 2, and the outer periphery of the metal wire mesh 2 and the inner edge of the window of the tensioned wire mesh 2 are bonded to each other through adhesive, and the tensioned wire mesh 2 is a polyester wire mesh in the shape of a Chinese character "Yu". The metal wire mesh 31 is woven from stainless steel wires in the warp and weft directions. Of course, the metal wire mesh 31 can also be woven from metal wires such as molybdenum wires. The printed side of the metal screen 31 is coated with a polymer film 32 , which is a film layer made of polymer materials such as PET, PE, PI, PU, ​​PVC, etc. The fine grid line grooves 4 and the main grid line grooves 5 are arranged in the printed area of ​​the polymer film 32 .

[0019] The fine grid line grooves 4 and the main grid line grooves 5 provided on the polymer film 32 are arranged perpendicular to each other, and the length direction of the fine grid line grooves 4 is parallel to the scraping direction of the scraper ( Figure 1 The main grid line grooves 5 are parallel and in the same direction (in the direction of the arrow in the middle), and correspondingly the main grid line grooves 5 are perpendicular to the scraping and pressing moving direction of the scraper; each main grid line groove 5 is connected with a number of fine grid line grooves 4 on both sides, so that the fine grid line grooves 4 are cross-connected with the main grid line grooves 5. The width of the stretched wire mesh 2 from one side edge of the printing screen 3 to the inner side edge of the printing plate frame 1 is L1, and the width of the stretched wire mesh 2 from the other side edge of the printing screen 3 to the other side inner side edge of the printing plate frame 1 is L2, L1=5cm, L2=2.5cm. Preferably L1=(1.5-2.5)L2. The width direction of the side width L1 of the above-mentioned stretched wire mesh 2 is set along the scraping and pressing moving direction of the scraper.

[0020] like Figure 4 As shown, the fine grid line grooves 4 are respectively arranged on both sides of the main grid line groove 5 in an interlaced manner; the fine grid line grooves 4 on one side of the main grid line groove 5 are correspondingly located between two adjacent fine grid line grooves 4 on the other side of the main grid line groove 5. The distance between the center lines of the two fine grid line grooves 4 on the same side of the main grid line groove 5 is A; the distance between the center lines of the fine grid line groove 4 on one side of the main grid line groove 5 and the adjacent fine grid line groove 4 on the other side is B, B=1 / 2A. That is, the center line of the fine grid line groove 4 on one side of the main grid line groove 5 can extend to the middle position of the center line of the adjacent fine grid line groove 4 on the other side. The slot width of the fine grid line groove 4 is between 8μm and 15μm.

[0021] The main grid line slot 5 is narrowed from its middle position to its two ends, that is, the slot width in the middle of the main grid line slot 5 is the widest and gradually narrows toward the two ends, and its narrowing angle α is 3.5°, and the narrowing angle α is the angle between the slot edges on both sides of the main grid line slot 5, and the slot edges on both sides of the main grid line slot 5 are symmetrically arranged relative to the center line of the slot. Preferably, the narrowing angle α of the main grid line slot 5 is 3°-6°.

[0022] The above-mentioned preferred embodiments of the present invention are listed, but the present invention is not limited thereto. There are many improvements and changes without violating the basic principles of the present invention. For example, the printing screen 3 is not limited to being composed of two components including a metal mesh 31 and a polymer film 32; it can also be composed of a single metal sheet, such as a 0.026mm thick stainless steel sheet, and a plurality of thin metal wires are sparsely fixed on one side of the metal sheet to prevent the metal sheet island blocks from falling off when the fine grid line grooves 4 and the main grid line grooves 5 are arranged on the same metal sheet at the same time. Of course, the fine grid line grooves and the main grid line grooves can also be arranged on two metal sheets respectively, and the fine grid line and the main grid line structure can be formed on the same battery cell by overprinting. All of the above-mentioned improvements and changes fall within the protection scope of the present invention.

Claims

1. A solar photovoltaic cell gradient staggered grid printing screen, comprising a printing plate frame (1) and a printing screen (3), wherein the printing screen (3) is stretched on the printing plate frame (1) through a stretched wire mesh (2), and characterized in that: The printing screen (3) is provided with a plurality of fine grid line grooves (4) and main grid line grooves (5), the fine grid line grooves (4) and the main grid line grooves (5) are cross-connected with each other, and a plurality of fine grid line grooves (4) are staggeredly provided on both sides of each main grid line groove (5); the main grid line grooves (5) are narrowed from the middle to both ends, and the narrowing angle α of the main grid line grooves (5) is 3°-6°; the width of the stretched wire mesh (2) from one side of the printing screen (3) to the printing plate frame (1) is L1, and the width of the stretched wire mesh (2) from the other side of the printing screen (3) to the printing plate frame (1) is L2, and L1=(1.5-2.5)L2.

2. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The printing screen (3) comprises a metal mesh (31) and a polymer film (32), wherein the polymer film (32) is coated on the metal mesh (31), and the fine grid line grooves (4) and the main grid line grooves (5) are arranged on the polymer film (32).

3. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The printing screen (3) is a metal thin plate, and the fine grid line grooves (4) and the main grid line grooves (5) are arranged on the metal thin plate.

4. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, 2 or 3, characterized in that: The fine grid line groove (4) on one side of the main grid line groove (5) is correspondingly located between two adjacent fine grid line grooves (4) on the other side of the main grid line groove (5).

5. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The fine grid line grooves (4) are perpendicular to the main grid line grooves (5), and a plurality of the fine grid line grooves (4) are parallel to each other.

6. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The two groove sides of the main grid line groove (5) are symmetrically arranged on both sides of the groove center line, and the narrowing angle α of the main grid line groove (5) is 3.5°.

7. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The width L1 of one side of the stretched wire mesh (2) is twice the width L2 of the other side.

8. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The fine grid line grooves (4) are arranged along the scraping and pressing moving direction of the scraper, and the side width L1 of the stretched wire mesh (2) is arranged along the scraping and pressing moving direction of the scraper.

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