Stress release structure of photovoltaic screen printing plate

Abstract

The utility model relates to the technical field of metalized printing screens of photovoltaic cells, and discloses a stress release structure of a photovoltaic screen, which comprises a stress release structure body arranged in a peripheral non-printing area of a printing pattern area of an electroforming nickel screen in a surrounding manner. The stress release structure body and the printed pattern area are integrally formed on the electroforming nickel film, and the stress release structure body is a sectional type discontinuous groove body. According to the utility model, the problems of poor tension control and low size and line width precision of the traditional single-layer groove structure can be solved through the matching of the stress release groove group with the double-layer stepped cross section and the gradually-changed spacing layout, and meanwhile, the problems of stress linkage conduction and easy cracking of a continuous closed-loop groove can be solved through the matching of the sectional discontinuous groove body and the connecting rib, so that the service life of the continuous closed-loop groove is prolonged. And the purposes of minimizing stress concentration, avoiding aging failure and having ultra-long service life are achieved through the matching of the arc chamfer and the electroforming integrally-formed structure.

Description

Technical Field

[0001] This utility model relates to the field of metallization printing screen technology for photovoltaic cells, specifically a stress relief structure for a photovoltaic screen. Background Technology

[0002] As photovoltaic cells develop towards larger sizes, thinner wafers, and higher efficiency, electroformed nickel full-aperture screens have become the core solution for printing fine grid lines and low silver consumption. To solve the problems of tension concentration, screen deformation, thick edge grid lines, and grid breakage during the screen stretching and printing process, the industry generally sets stress relief structures around the printing graphic area.

[0003] Existing technologies generally employ a longitudinal stress-relief zone made of elastic material and a single-layer, continuously enclosed annular groove with equal spacing. This can only passively cut off stress in a single way and cannot adapt to the dynamic tension distribution throughout the entire screen stretching and printing process. Conventional equal-spacing continuous closed-loop structures cannot match the tension differences in different areas of the screen, which easily leads to local stress concentration, groove cracking, and screen edge breakage. Ultra-thin screens have short lifespans, and single-layer structures cannot simultaneously address tension release and printing linewidth control. Large-size screens have large dimensional and linewidth differences, resulting in low printing yields. Furthermore, the elastic stress-relief zone is susceptible to high-temperature aging and interlayer delamination, making it unsuitable for high-speed mass production scenarios. Therefore, we propose a stress-relief structure for photovoltaic screens to solve the above problems. Utility Model Content

[0004] The purpose of this invention is to provide a stress relief structure for photovoltaic screen printing, which solves the technical problems of existing stress relief structures, such as insufficient tension control, easy cracking due to stress concentration, poor dimensional and linewidth accuracy, short screen life, and inability to adapt to high-speed printing of large-size ultra-thin electroformed screens.

[0005] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution:

[0006] This utility model relates to a stress relief structure for a photovoltaic screen printing plate, comprising a stress relief structure body. The stress relief structure body is arranged around the non-printing area surrounding the printing pattern area of ​​the electroformed nickel screen printing plate. The stress relief structure body and the printing pattern area are integrally formed on the electroformed nickel film. The stress relief structure body is a segmented discontinuous groove. Each segment of the groove has a double-layer stepped cross-section structure. The opening spacing between adjacent segments of the groove is continuously and gradually changed. All right-angle transitions on the inner wall of the groove are provided with rounded chamfers.

[0007] Furthermore, the double-layer stepped cross-section structure includes a first groove near the scraper surface and a second groove near the printing surface. The first groove and the second groove are coaxially arranged. The width of the first groove is 100-150μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film. The width of the second groove is 20-30μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film.

[0008] Furthermore, along the direction of the scraper's movement, from both ends of the screen to the center, the center-to-center distance between adjacent grooves gradually changes from 2mm to 0.5mm.

[0009] Furthermore, the segmented discontinuous tank has a single segment length of 10-20mm, and a connecting rib with a width of 0.5-1mm is provided between two adjacent tank segments. The connecting rib is integrally formed with the electroformed nickel film body.

[0010] Furthermore, the radius of the chamfered arc is R0.01mm-R0.03mm.

[0011] Furthermore, the thickness of the electroformed nickel film is 15-30 μm, and the material is any one of pure nickel, nickel-cobalt alloy, or nickel-phosphorus alloy.

[0012] Furthermore, the depth ratio of the first tank to the second tank is 1:3 to 3:1.

[0013] Furthermore, it includes a frame, a screen mesh, an electroformed nickel film, a printed graphic area on the electroformed nickel film, and a stress relief structure for the photovoltaic screen.

[0014] Furthermore, the stress relief structure is micro-trimmed by femtosecond laser, with burrs on the edge of the groove ≤0.3μm and no stress concentration points on the rounded chamfered surface.

[0015] Furthermore, the screen is adapted for printing large-size photovoltaic cells of 210mm and above, with a full-width tension difference of ≤1N / cm after stretching, and a printing grid line width difference of ≤1μm.

[0016] This utility model has the following beneficial effects:

[0017] This invention solves the problems of poor tension control and low dimensional and linewidth accuracy of traditional single-layer groove structures by combining a double-layer stepped cross-section stress relief groove group with a gradually varying spacing layout. At the same time, the combination of segmented discontinuous grooves and connecting ribs solves the problems of stress chain transmission and easy cracking in continuous closed-loop grooves. Furthermore, the combination of rounded chamfers and electroforming integrated molding structure achieves the goals of minimizing stress concentration, preventing aging failure, and extending service life. Therefore, this device solves the core pain points of traditional electroforming screen printing stress relief structures, such as poor adaptability, short lifespan, and high printing defect rate, realizing full-process graded stress control for large-size ultra-thin screen printing, and significantly improving printing accuracy and service life.

[0018] Of course, any product implementing this utility model does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the planar layout structure of this utility model;

[0022] Figure 3 This is a schematic diagram of the double-layer stepped cross-sectional structure in this utility model;

[0023] Figure 4 This is a partially enlarged schematic diagram of the continuous gradient structure in this utility model.

[0024] The attached diagram lists the components represented by each number as follows:

[0025] In the diagram: 1. Stress relief structure body; 2. Electroformed nickel film; 3. Printed pattern area; 4. Segmented discontinuous groove; 5. First groove; 6. Second groove; 7. Rounded chamfer; 8. Connecting rib. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figures 1-4As shown, this utility model is a stress relief structure for a photovoltaic screen printing plate, including a stress relief structure body 1. The stress relief structure body 1 is arranged around the non-printing area of ​​the printing pattern area 3 of the electroformed nickel screen printing plate. The stress relief structure body 1 and the printing pattern area 3 are integrally formed on the electroformed nickel film 2. The stress relief structure body 1 is a segmented discontinuous groove 4. Each segment of the groove has a double-layer stepped cross-section structure. The opening spacing between adjacent segments of the groove is continuously and gradually changed. All right-angle transitions on the inner wall of the groove are provided with rounded chamfers 7. The electroformed nickel film 2 is the main substrate of the photovoltaic screen printing plate, with a thickness of 15-30μm. The material is one of pure nickel, nickel-cobalt alloy or nickel-phosphorus alloy. It is integrally formed with the printing pattern area 3 and the stress relief groove group through electroforming process, without adhesive layer or additional elastic material, avoiding the risk of high-temperature aging and interlayer peeling, ensuring structural stability and mass production consistency, and providing a high-strength and high-flatness base carrier for printing and stress relief.

[0028] The double-layer stepped cross-section structure includes a first groove 5 near the squeegee surface and a second groove 6 near the printing surface. The first groove 5 and the second groove 6 are coaxially arranged. The width of the first groove 5 is 100-150μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film 2. The width of the second groove 6 is 20-30μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film 2. The printing pattern area 3 is located in the central area of ​​the electroformed nickel film 2 and is the functional area for printing the grid lines of the battery cell. It is arranged coaxially around the stress relief groove group, which forms an outer protection for it. Through graded stress relief, the tension fluctuations during the stretching and printing process are reduced, ensuring the dimensional accuracy and flatness of the printing pattern area 3, avoiding problems such as thick edge grid lines and broken grids, and improving the printing yield.

[0029] Along the direction of the scraper's movement, from both ends of the screen to the center, the center-to-center distance between adjacent grooves gradually changes from 2mm to 0.5mm. The length of a single segment of the segmented discontinuous groove 4 is 10-20mm. A connecting rib 8 with a width of 0.5-1mm is provided between two adjacent groove segments. The connecting rib 8 is integrally formed with the electroformed nickel film 2. The connecting rib 8 is integrally formed between two adjacent stress relief groove segments, with a width of 0.5-1mm, and is of the same material and structure as the electroformed nickel film 2. The segmented groove, together with the connecting rib 8, can cut off the stress chain transmission path, avoid local overload leading to the overall screen breaking, and at the same time ensure the overall rigidity and tear resistance of the screen, balancing the stress relief effect and structural strength, which is different from the defect of traditional continuous closed-loop grooves that are prone to breaking.

[0030] The radius of the rounded chamfer 7 is R0.01mm-R0.03mm, the thickness of the electroformed nickel film 2 is 15-30μm, and the material is any one of pure nickel, nickel-cobalt alloy or nickel-phosphorus alloy. The depth ratio of the first groove 5 to the second groove 6 is 1:3 to 3:1. The rounded chamfer 7 is set at the right-angle transition of all inner walls of the stress relief groove group, with a chamfer radius of R0.01mm-R0.03mm. Combined with the femtosecond laser micro-trimming process, it removes processing burrs, optimizes the smoothness of the groove, effectively disperses the stress concentration at the groove, significantly reduces the cracking risk of the ultra-thin electroformed nickel film 2, improves the fatigue life of the screen, and solves the problem of stress concentration in traditional right-angle grooves.

[0031] The system includes a screen frame, a screen printing cloth, and an electroformed nickel film 2. The electroformed nickel film 2 has a printing pattern area 3. The stress relief structure undergoes femtosecond laser micro-trimming, resulting in burrs on the groove edges ≤0.3μm. The rounded chamfers 7 have no stress concentration points on the surface. The screen is suitable for printing large-size photovoltaic cells of 210mm and above. After stretching, the tension difference across the entire width is ≤1N / cm, and the line width difference of the printed grid lines is ≤1μm. The stress relief groove assembly consists of multiple independent grooves in a segmented, non-continuous ring layout. Each segment is 10-20mm long and runs along the direction of the squeegee movement. The center-to-center spacing between adjacent grooves gradually changes from 1.8mm to 0.8mm to adapt to the stress distribution pattern of high stress at both ends and low stress at the center of the screen. Each groove section adopts a double-layer stepped cross-section, including a first groove 5 near the squeegee surface and a second groove 6 near the printing surface. The first groove 5 has a width of 100-150μm and a depth of 1 / 2 film thickness, while the second groove 6 has a width of 20-30μm and a depth of 1 / 2 film thickness. This achieves two-level stress control, with the wide groove on the squeegee surface buffering stress and the narrow groove on the printing surface controlling line width, thus balancing tension release and printing accuracy.

[0032] This photovoltaic screen printing stress relief structure, in its use, firstly involves stretching and fixing the electroformed nickel film 2, which has an integrally formed stress relief groove assembly, to the screen frame and screen cloth. During the stretching process, the segmented discontinuous groove 4, together with the connecting rib 8, cuts off the stress chain transmission. The double-layer stepped groove achieves primary and secondary level buffering, and the rounded chamfer 7 disperses the groove opening stress, avoiding screen warping and dimensional deviations. Secondly, during photovoltaic cell printing, the first groove 5 on the squeegee surface buffers the impact of squeegee movement to prevent ink diffusion, while the second groove 6 on the printing surface precisely releases local stress. The pressure is used to ensure uniform tension in the printed graphic area 3, and stable line width and size. Then, the groove spacing gradually changes along the squeegee direction to match the actual tension distribution. The tension difference across the entire width is controlled within 1 N / cm, the dimensional difference is ≤0.01 mm, and the line width difference is ≤1 μm. Then, during long-term high-speed printing, there is no aging of elastic materials, no interlayer peeling, no cracking of the groove, and the screen life is increased to 300,000-500,000 times. Finally, after the printing life cycle is completed, the electroformed nickel film 2 can be recycled as a whole, and the stress release structure is undamaged and undeformed, maintaining structural integrity.

[0033] The preferred embodiments of this utility model disclosed above are merely illustrative of the present utility model. These preferred embodiments do not exhaustively describe all details, nor do they limit the utility model to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it. This utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A stress relief structure for a photovoltaic grid, comprising a stress relief structure body (1), characterized in that: The stress relief structure body (1) is arranged around the non-printing area of ​​the electroformed nickel screen printing pattern area (3). The stress relief structure body (1) and the printing pattern area (3) are integrally formed on the electroformed nickel film (2). The stress relief structure body (1) is a segmented discontinuous tank (4). Each segment of the tank has a double-layer stepped cross-section structure. The opening spacing between two adjacent segments of the tank is continuously and gradually changed. All right-angle transitions on the inner wall of the tank are provided with rounded chamfers (7).

2. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The double-layer stepped cross-section structure includes a first groove (5) near the scraper surface and a second groove (6) near the printing surface. The first groove (5) and the second groove (6) are coaxially arranged. The width of the first groove (5) is 100-150μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film (2). The width of the second groove (6) is 20-30μm and the depth is 1 / 2 of the total thickness of the electroformed nickel film (2).

3. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: Along the direction of the scraper's movement, from both ends of the screen to the center, the center-to-center distance between adjacent grooves gradually changes from 2mm to 0.5mm.

4. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The segmented discontinuous tank (4) has a single segment length of 10-20mm, and a connecting rib (8) with a width of 0.5-1mm is provided between two adjacent tank segments. The connecting rib (8) is integrally formed with the electroformed nickel film (2).

5. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The radius of the circular chamfer (7) is R0.01mm-R0.03mm.

6. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The electroformed nickel film (2) has a thickness of 15-30 μm and is made of any one of pure nickel, nickel-cobalt alloy or nickel-phosphorus alloy.

7. The stress relief structure of a photovoltaic grid according to claim 2, characterized in that: The depth ratio of the first groove (5) to the second groove (6) is 1:3 to 3:

1.

8. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: It includes a frame, a screen mesh, an electroformed nickel film (2), wherein the electroformed nickel film (2) is provided with a printed graphic area (3), and a stress relief structure for a photovoltaic screen as described in any one of claims 1-7.

9. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The stress relief structure is micro-trimmed by femtosecond laser, with burrs on the edge of the groove ≤0.3μm and no stress concentration points on the surface of the rounded chamfer (7).

10. The stress relief structure of a photovoltaic grid according to claim 1, characterized in that: The screen is suitable for printing large-size photovoltaic cells of 210mm and above. After stretching, the tension difference across the entire width is ≤1N / cm, and the line width difference of the printed grid lines is ≤1μm.

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