Solar photovoltaic cell gradual change staggered grid printing screen

Abstract

The utility model 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, the fine grid line grooves and the main grid line grooves are communicated in a crossed mode, and the fine grid line grooves are communicated with the main grid line grooves. 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 fine grid line grooves on one side of the main grid line grooves are correspondingly located between the two adjacent fine 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] This utility model relates to a printing template for precision conductive grid lines of solar photovoltaic cells, and more particularly to a printing template for conductive grid lines with fine grid line grooves arranged in an alternating pattern. Background Technology

[0002] The front grid of a solar photovoltaic cell consists of at least one main grid line and several sub-grid lines (fine grid lines) connected to the main grid line. The sub-grid lines guide the current generated by the photovoltaic effect of the semiconductor material. The main grid line collects the current from each sub-grid line and transmits it through the solder strips welded on it.

[0003] Currently, the printing of grid lines in solar photovoltaic cells is mostly achieved using screen printing technology. During screen printing, silver paste is applied to the silicon wafer by scraping and squeezing the screen printing plate with a squeegee. The springback tension of the screen printing plate is provided by the polyester mesh surrounding the metal mesh. The tension provided by the polyester mesh to the metal mesh directly affects the quality of the printed grid lines. Uneven tension changes in the metal mesh during printing can easily lead to distortion in the shape of the printed grid lines and fluctuations in the aspect ratio.

[0004] Meanwhile, since the sub-grid lines on both sides of the main grid line on the current solar cell are located on the same straight line, the corresponding printing grooves of the sub-grid lines on the screen printing plate are also located on a straight line. In this way, the two sub-grid line grooves located on the same straight line are prone to pulling and tearing the two sides of the main grid line groove, causing deformation and warping of the main grid line groove. Since the main grid line groove and the sub-grid line groove are interconnected, the deformation of the main grid line groove will inevitably cause deformation of the groove shape of the sub-grid line groove and warping of the groove edge. The deformation and warping of the printed groove directly affect the appearance of the printed grid line corresponding to the groove and the integrity of the grid line pattern. This causes phenomena such as paste splashing, diffusion, and uneven thickness at the two sides of the printed groove, resulting in incomplete phenomena such as broken lines or uneven line height and thickness of the printed grid line electrode, which increases the impedance of the electrode pattern and reduces the conversion efficiency of the solar cell. Utility Model Content

[0005] In view of the above-mentioned shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a solar photovoltaic cell gradient staggered grid printing screen, which can not only effectively balance the printing plate tension and avoid the deformation of the printing plate groove, but also save a lot of printing silver paste and effectively reduce the production cost of solar photovoltaic cells.

[0006] To solve the above-mentioned technical problems, the present invention provides a solar photovoltaic cell gradient staggered grid printing screen, comprising a printing plate frame and a printing screen. The printing screen is stretched onto the printing plate frame by a tensioned wire mesh. The printing screen is provided with a plurality of fine grid grooves and main grid grooves, which are interconnected and intersecting each other. Each main grid groove has a plurality of fine grid grooves staggered on both sides. The main grid grooves narrow from the middle to both ends, with a narrowing angle α = 3°–6°. The width of the tensioned wire mesh between one side of the printing screen and the printing plate frame is L1, and the width of the tensioned wire mesh between the other side of the printing screen and the printing plate frame is L2, where L1 = (1.5–2.5)L2.

[0007] Preferably, the printing screen comprises a metal mesh and a polymer film, the polymer film being coated on the metal mesh, and the fine grid grooves and main grid grooves being disposed on the polymer film.

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

[0009] Preferably, the fine grid groove on one side of the main grid groove is located between two adjacent fine grid grooves on the other side of the main grid groove.

[0010] Preferably, the fine grid grooves are perpendicular to the main grid grooves, and the plurality of fine grid grooves are parallel to each other.

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

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

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

[0014] In the above structure, since several fine grid grooves are staggered on both sides of the main grid groove, the pulling and tearing of the groove sides is avoided, the tension of the tensioning screen is evenly distributed, and the deformation of the main grid groove and the sub-grid groove caused by such pulling and uneven tension is prevented. When the squeegee moves along the length of the printing plate groove, the squeegee pressure tension is applied to the tensioning screen and the screen coating in a staggered and sequential manner as the squeegee moves. This staggered and sequential action of the tension force can effectively avoid the stretching deformation of the printing plate groove, which is beneficial to the accurate printing of the grid lines of the battery cell. Furthermore, since the main grid groove gradually narrows from the middle to both ends, the secondary grid current that can be collected at the ends of the main grid groove is small, so the width of the main grid line at the ends is narrower. On the other hand, the secondary grid current collected in the middle part of the main grid line is large, so the groove is wider. This not only reduces the light-shielding area of ​​the main grid line on the cell, which is beneficial to increasing the light-receiving area and power generation of the cell, but also effectively saves expensive silver paste material, thereby reducing the production cost of solar cells. Furthermore, by employing unequal width tensioned wire meshes on the perpendicular sides of the printing screen, with the width of the tensioned wire mesh along the squeegee's pressing path being greater than that on the other side, greater elasticity is generated in the squeegee path direction than in the other direction. During the squeegee pressing process, the grooves can more easily adhere to the battery substrate under the action of the squeegee, achieving precise printing. Moreover, the printing plate rebounds more quickly and reliably after printing. More importantly, this unequal width tensioned wire mesh setting effectively reduces the variation in tension force along the width direction of the printing plate grooves, suppressing and preventing groove deformation and warping, avoiding ink leakage caused by groove deformation, and ensuring precise printing of fine grid lines. (See attached diagram)

[0015] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the present invention's gradient staggered grid printing screen for solar photovoltaic cells.

[0016] Figure 1 is a structural schematic diagram of a specific embodiment of the gradient staggered grid printing screen of the present invention for solar photovoltaic cells;

[0017] Figure 2 is a cross-sectional view of Figure 1;

[0018] Figure 3 is an enlarged view of part I in Figure 2;

[0019] Figure 4 is an enlarged view of part II in Figure 1.

[0020] In the diagram, 1—printing plate frame, 2—tensioned wire mesh, 3—printing screen, 31—metal wire mesh, 32—polymer film, 4—fine grid groove, and 5—main grid groove. Detailed Implementation

[0021] As shown in Figures 1, 2, and 3, the solar photovoltaic cell gradient staggered printing screen includes a printing plate frame 1, which is a rectangular frame made of aluminum alloy. A window for stretching the printing screen 3 and tensioning the wire mesh 2 is located at the center of the printing plate frame 1.

[0022] The printing screen 3 includes a metal wire mesh 31 and a polymer film 32 that are adhered to each other. The metal wire mesh 31 is stretched onto the bottom side of the printing plate frame 1 by a tension wire mesh 2. The outer perimeter of the metal wire mesh 2 and the inner edge of the window of the tension wire mesh 2 are bonded together with adhesive. The tension wire mesh 2 is a polyester wire mesh in a U-shape. 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 wire. The printing side of the metal wire mesh 31 is covered with a polymer film 32, which is a film layer made of polymer materials such as PET, PE, PI, PU, ​​and PVC. Fine grid grooves 4 and main grid grooves 5 are set in the printing area of ​​the polymer film 32.

[0023] The fine grid grooves 4 and main grid grooves 5, set on the polymer film 32, are arranged perpendicularly to each other, and the longitudinal direction of the fine grid grooves 4 is parallel and in the same direction as the scraping and pressing direction of the squeegee (arrow direction in Figure 1). Correspondingly, the main grid grooves 5 are perpendicular to the scraping and pressing direction of the squeegee. Each main grid groove 5 has several fine grid grooves 4 connected to both sides, so that the fine grid grooves 4 and the main grid grooves 5 are intersecting and connected. The width of the tension mesh 2 between one side of the printing screen 3 and the inner side of the printing plate frame 1 is L1, and the width of the tension mesh 2 between the other side of the printing screen 3 and the other inner side of the printing plate frame 1 is L2, L1=5cm, L2=2.5cm. Preferably, L1=(1.5—2.5)L2. The width L1 of the side of the tension mesh 2 is set along the scraping and pressing direction of the squeegee.

[0024] As shown in Figure 4, fine grid grooves 4 are staggered on both sides of the main grid groove 5; the fine grid groove 4 on one side of the main grid groove 5 is located between two adjacent fine grid grooves 4 on the other side of the main grid groove 5. The distance between the center lines of two fine grid grooves 4 on the same side of the main grid groove 5 is A; the distance between the center lines of a fine grid groove 4 on one side of the main grid groove 5 and an adjacent fine grid groove 4 on the other side is B, where B = 1 / 2A. That is, the center line of a fine grid groove 4 on one side of the main grid groove 5 can extend to the middle position of the center line of an adjacent fine grid groove 4 on the other side. The groove width of the fine grid groove 4 is between 8μm and 15μm.

[0025] The main grid groove 5 narrows from its middle position towards both ends, meaning the groove width is widest in the middle and gradually narrows towards both ends. The narrowing angle α = 3.5°, which is the included angle between the two sides of the main grid groove 5, and the two sides of the main grid groove 5 are symmetrically arranged relative to its center line. Preferably, the narrowing angle α of the main grid groove 5 is 3°–6°.

[0026] The above describes preferred embodiments of the present invention, but the present invention is not limited thereto, and many improvements and modifications are possible without departing from the basic principles of the present invention. For example, the printing screen 3 is not limited to consisting of two components: 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, with several fine metal wires sparsely fixed on one side of the metal sheet to prevent the metal sheet islands from falling off when fine grid grooves 4 and main grid grooves 5 are arranged on the same metal sheet simultaneously. Of course, the fine grid grooves and main grid grooves can also be set on two separate metal sheets, and the fine grid lines and main grid lines structure can be formed on the same battery cell by overprinting. All of the above improvements and modifications fall within the protection scope of the present invention.

Claims

1. A gradient staggered grid printing screen for solar photovoltaic cells, comprising a printing plate frame (1) and a printing screen (3), wherein the printing screen (3) is stretched onto the printing plate frame (1) by a tensioned wire mesh (2), characterized in that: The printing screen (3) is provided with a number of fine grid grooves (4) and main grid grooves (5). The fine grid grooves (4) and main grid grooves (5) are interconnected and intersected. Each main grid groove (5) is provided with a number of fine grid grooves (4) on both sides. The main grid grooves (5) narrow from the middle to both ends, and the narrowing angle α of the main grid grooves (5) is 3°-6°. The width of the tension wire mesh (2) between one side of the printing screen (3) and the printing plate frame (1) is L1, and the width of the tension wire mesh (2) between the other side of the printing screen (3) and the printing plate frame (1) is L2. 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) includes a metal wire mesh (31) and a polymer film (32), which is covered on the metal wire mesh (31). The fine grid groove (4) and the main grid groove (5) are disposed 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 thin metal plate, and the fine grid groove (4) and the main grid groove (5) are disposed on the thin metal plate.

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

5. The solar photovoltaic cell gradient staggered grid printing screen according to claim 1, characterized in that: The fine grid groove (4) is perpendicular to the main grid groove (5), and several of the fine grid 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 sides of the main grid groove (5) are symmetrically positioned on both sides of the center line of the groove, and the narrowing angle α of the main grid 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 tensioned 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 groove (4) is arranged along the scraping and pressing direction of the scraper, and the side width L1 of the tension wire mesh (2) is set along the scraping and pressing direction of the scraper.

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