Meshless screen and method of making the same

Abstract

The application discloses a screen without knot and a preparation method thereof. The method comprises the following steps: step 1, stretching a screen gauze, the warp and weft of the screen gauze are made of different materials; step 2, etching the screen gauze; step 3, scanning the etched screen gauze to obtain a laser wiring drawing; and step 4, introducing the laser wiring drawing into a laser cutting machine, cutting a carrier covered on the screen gauze by the laser cutting machine to obtain the screen without knot. The scheme can improve the strength of the screen, the printing precision and the service life of the screen.

Description

Technical Field

[0001] This invention relates to the field of screen printing technology, specifically to a meshless screen and its preparation method. Background Technology

[0002] Screen printing is a printing technique that utilizes the basic principle that ink passes through the mesh openings of a screen in the patterned areas, while the non-patterned areas are impermeable. Using screen printing technology, conductive ink containing metal can be precisely imprinted onto a substrate through the mesh openings of a screen.

[0003] Screen printing technology is widely used in the manufacture of solar cell grid lines due to its advantages such as ease of operation and suitability for large-area production. However, as grid lines become increasingly ultra-fine, conventional screen printing plates, due to the presence of knots, are prone to problems such as broken grid lines and incomplete printing when producing ultra-fine grid lines, making it difficult to guarantee grid line quality. Therefore, knot-free screen printing plates have emerged.

[0004] The mainstream methods for preparing knotless screen printing plates currently include the following steps: screen stretching → yarn drawing → PI film lamination → laser cutting of PI. Knotless screen printing plates prepared by this method are shown below. Figure 1 As shown. This method requires drawing the yarn, which can cause some damage to the mesh, resulting in deformation. The deformed mesh produces grid lines with lower precision, leading to poor overlap between the main grid and the fine grid, thus affecting battery efficiency. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, embodiments of the present invention provide a knotless screen and its preparation method, which are used to solve the above problems.

[0006] This application discloses a method for preparing a knotless screen printing plate, comprising the following steps:

[0007] Step 1: Spread the mesh, wherein the warp and weft threads of the mesh are made of different materials;

[0008] Step 2: Etch the mesh;

[0009] Step 3: Scan the etched mesh to obtain the laser trace pattern;

[0010] Step 4: Import the laser wiring pattern into the laser cutting machine, and use the laser cutting machine to cut the carrier covering the mesh to obtain a knotless mesh.

[0011] Specifically, in step 3, the steps for scanning the etched mesh and obtaining the laser trace pattern include:

[0012] Step 3-1: Place the etched mesh onto a scanner for scanning. The scanner scans at least a portion of the warp threads of the mesh and generates the center line of every two adjacent warp threads.

[0013] Step 3-2: Based on the product graphic parameters, select and retain the center line corresponding to the product graphic, and discard the rest of the center lines. Process the retained center lines according to the product graphic to obtain the laser routing drawing.

[0014] Specifically, in step 3-2, the method for selecting and retaining the center line corresponding to the product graphic is as follows:

[0015] One grid line in the product graphic is defined as the first grid line, and the other grid lines are respectively theoretically distanced from the first grid line;

[0016] Define a center line as the first center line, which corresponds to the first grid line. Starting from the position of the first center line, measure the actual distance between the remaining center lines and the first center line in sequence.

[0017] Multiple actual distances and multiple theoretical distances are compared, and the centerline with the closest actual and theoretical distances is retained.

[0018] Specifically, the difference between each actual distance and the corresponding theoretical distance is greater than or equal to -80 μm and less than or equal to 80 μm.

[0019] Specifically, when the difference between the actual distance of multiple centerlines and a theoretical distance is between -80μm and 80μm, the centerline corresponding to the difference with the smallest absolute value is retained.

[0020] Specifically, in step 2, the mesh is divided into printed and non-printed areas according to the product graphic parameters, and the warp threads in the printed area are etched.

[0021] Specifically, the warp is made of tungsten steel, the weft is made of stainless steel, and the etching solution I used to etch the warp contains H2O2 and NH4OH.

[0022] Specifically, the warp is made of stainless steel, the weft is made of tungsten carbide, and the etching solution II used to etch the warp contains FeCl3∙6H2O and concentrated hydrochloric acid.

[0023] Specifically, the carrier is a PI film.

[0024] Specifically, in step 1, after the mesh is stretched, the direction of the polyester mesh warp is consistent with the direction of the mesh yarn warp, and the direction of the polyester mesh weft is consistent with the direction of the mesh yarn weft; the tension of the polyester mesh warp is greater than the tension of its weft.

[0025] This application also discloses a knotless screen, which is prepared using the method described in this embodiment.

[0026] The present invention has at least the following beneficial effects:

[0027] 1. Compared with the traditional wire drawing method, the method of this embodiment increases the distance between two adjacent warp threads by etching the warp threads to achieve the preparation of a knotless screen. Since there is no need to draw the wire and local etching is possible, the strength of the mesh is less affected. Therefore, the mesh can still maintain sufficient strength, which can avoid the problem of poor printing accuracy caused by deformation. At the same time, it also improves the service life of the screen and reduces the user's product consumption by 30%.

[0028] 2. The solution in this embodiment scans the etched mesh and generates a laser routing pattern. During the scanning process, a center line between two adjacent warp lines is automatically generated. The center line is then compared with the product grid line position in real time to select the center line that matches the product grid line, thereby improving the routing accuracy from 10μm to 5μm.

[0029] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of an existing meshless grid plate;

[0032] Figure 2 This is a schematic diagram of the structure of the knotless mesh plate in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the center line retained after the mesh is scanned in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the laser trace drawing in an embodiment of the present invention.

[0035] The reference numerals in the above figures are: 1. Meridians; 2. Parallels. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "fixing," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] In this invention, unless otherwise explicitly 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," "below," and "over" 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 below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, 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 limiting the scope of protection of this application.

[0040] Furthermore, the terms "first" and "second" are used only to distinguish between different terms in description and do not have any special meaning.

[0041] Combination Figures 2 to 4 As shown, the preparation method of the knotless screen printing plate in this embodiment includes the following steps:

[0042] Step 1: The mesh is stretched, with the warp 1 and weft 2 made of different materials. Specifically, when the warp is made of tungsten carbide, the weft can be made of stainless steel; conversely, when the warp is made of stainless steel, the weft can be made of tungsten carbide. Preferably, during stretching, the tension in the warp and weft directions of the polyester mesh is different (warp tension > weft tension), and the angle direction of the polyester mesh is consistent with the diameter direction of the mesh yarn (the warp direction of the polyester mesh is consistent with the force direction of the warp yarn of the steel wire mesh, and the weft direction of the polyester mesh is consistent with the force direction of the weft yarn of the steel wire mesh), to balance the tension directions of the warp and weft yarns.

[0043] Step 2: Etch the mesh from Step 1. Specifically, according to the product graphic parameters (e.g., ... Figure 4 As shown, the product graphic parameters mainly include the position and length of the grid lines. The mesh is divided into printing and non-printing areas, and the warp threads within the printing area are etched. The printing area can be a continuous area or multiple discontinuous areas. Local etching of the mesh can be performed as needed to maintain its strength and avoid significant reduction in overall mesh strength due to full-mesh etching, which could lead to mesh deformation and affect printing accuracy. Etching the warp threads in the printing area can lower the warp thread diameter by approximately 3μm at the center, meeting the requirements for ultra-fine linewidth production. It should be noted that the product described in this embodiment refers to the product prepared using the knotless screen printing plate of this embodiment; therefore, the product graphic refers to the design drawing of this product.

[0044] Step 3: Scan the etched mesh to obtain the laser trace pattern (e.g., Figure 4 (As shown).

[0045] Step 4: Import the above laser wiring pattern into the laser cutting machine, and use the laser cutting machine to cut the carrier covering the mesh to obtain a knotless mesh (e.g., Figure 2 The carrier is preferably a PI film. In this embodiment, covering the carrier on the mesh (e.g., pressing the mesh with a PI film) is a post-process of mesh etching, which is a conventional technique in the art and will not be described in detail here.

[0046] In step 2 of this embodiment, when the warp material is tungsten carbide and the weft material is stainless steel, an alkaline hydrogen peroxide etching solution (defined as etching solution I) is used to chemically etch the mesh. Etching solution I contains H2O2 and NH4OH. Specifically, etching solution I, by volume percentage, contains: 15 vol% H2O2 solution, 10 vol% NH4OH solution, and 75 vol% deionized water. The concentration of the H2O2 solution is 30%, and the concentration of the NH4OH solution is 25%. Preferably, 0.1 vol% Triton X-100 can be added to etching solution I as a surfactant, while the contents of the H2O2 and NH4OH solutions remain unchanged. The mesh is immersed in etching solution I at a temperature between 30 and 35°C for 1 to 3 minutes, with samples taken every 30 seconds to measure the wire diameter. Slight magnetic stirring or ultrasonic assistance can be used during the etching process. According to the following reaction formula, tungsten is oxidized to tungstate ions (WO4). 2- It dissolves in water; NH4OH provides OH-. - Maintaining an alkaline environment; under these conditions, a Cr2O3 / Fe2O3 passivation film is formed on the surface of stainless steel (Fe-Cr-Ni), which is not etched. Therefore, the etching of a single thread (warp) of the mesh is achieved.

[0047] W + 3H₂O₂ + 2OH⁻ - →WO4 2- +4H2O (Reaction 1)

[0048] In step 2 of this embodiment, when the warp yarn is made of stainless steel and the weft yarn is made of tungsten carbide, an etching solution with another formulation (defined as etching solution II) can be used to etch the mesh. Etching solution II contains FeCl3∙6H2O and concentrated hydrochloric acid. Specifically, etching solution II contains: 30wt~40wt% FeCl3∙6H2O, 5vol~10vol% concentrated hydrochloric acid, and the balance being deionized water. The concentration of concentrated hydrochloric acid is 37%. The mesh is immersed in etching solution II at a temperature between 25~35℃ for etching, with an etching rate of 1~2μm / min. According to reactions two to four below, FeCl3∙6H2O is used to oxidize Fe, Cr, and Ni in the stainless steel; concentrated hydrochloric acid is used to provide Cl... - This damages the passivation film; WO3 is formed on the surface of tungsten steel, making it almost un-etched.

[0049] Fe + 2Fe 3+ →3Fe 2+ (Reaction 2)

[0050] Cr+3Fe 3+ →Cr 3+ +3Fe 2+ (Reaction 3)

[0051] Ni+2Fe 3+ →Ni 2+ +2Fe 2+ (Reaction Formula 4)

[0052] In step 3 of this embodiment, the specific steps for scanning the etched mesh and obtaining the laser trace pattern are as follows:

[0053] Step 3-1: Place the etched mesh onto the automatic scanner, ensure proper positioning, set the parameters, and begin scanning. The scanner scans at least a portion of the warp threads of the mesh and generates center lines between every two adjacent warp threads. Specifically, the scanner can scan all warp threads of the entire mesh or only the warp threads of the printing area. Each line in the preliminary drawing generated after scanning is not a warp thread of the mesh, but rather an automatically generated center line between two adjacent warp threads based on their position and size. For example, when the scanner scans the first to third warp threads on the mesh, it generates the center lines between the first and second warp threads, as well as the center lines between the second and third warp threads.

[0054] Step 3-2: Based on the product drawing parameters, select and retain the center lines corresponding to the product drawing; discard the remaining center lines. Then, based on the product drawing, refine the retained center line drawing (e.g., ...). Figure 3 The above laser routing diagram (as shown) is processed to obtain the above laser routing diagram (as shown). Figure 4 The method for processing the retained centerlines includes: combining the retained centerline drawing with other features in the product drawing besides fine grid lines (such as harpoon lines, gradient lines, chamfer lines, borders, etc.). During the combination process, the positional relationship between the retained centerline and other features in the product standard drawing is re-identified and judged to ensure it conforms to tolerance standards. Each retained centerline will become the trajectory line of the laser spot center during laser cutting of the PI film. That is to say, during laser cutting of the PI film, the movement trajectory (trajectory) of the spot center coincides with these centerlines. Each retained centerline will correspond to a grid line on the product.

[0055] Furthermore, in step 3-2, the specific method for selecting and retaining the center line corresponding to the product graphic is as follows:

[0056] Step 3-2-1: Define one grid line in the product graphic as the first grid line. The remaining grid lines each have a corresponding theoretical distance from this first grid line, and each theoretical distance is unique. For example... Figure 4 In this process, the first grid line at the top of the product is defined as the first grid line, and the remaining grid lines are ordered sequentially. Each grid line has a theoretical distance from the first grid line. These theoretical distance parameters are then written into the scanner software to generate the scanning program.

[0057] Step 3-2-2: Define one of the multiple center lines generated after the scanner scans the warp lines as the first center line, which corresponds to the first grid line mentioned above. In other words, the first grid line can be printed through the through-hole formed on the PI film by the first center line. Starting from the position of the first center line, measure the actual distance between the remaining center lines and the first center line in sequence.

[0058] Step 3-2-3: Each time the actual distance between a centerline and the first centerline is measured, this actual distance is compared with the multiple theoretical distances mentioned above. When the actual distance of a centerline matches the first centerline to an equal or closest theoretical distance, that centerline is retained. The standard for the actual distance and theoretical distance to be close is that the difference between the two is greater than or equal to -80μm (in this case, the actual distance is less than the theoretical distance, i.e., the distance between the centerline and the first centerline is less than the distance between the corresponding grating line and the first grating line), and less than or equal to 80μm (in this case, the actual distance is greater than the theoretical distance, i.e., the distance between the centerline and the first centerline is greater than the distance between the corresponding grating line and the first grating line). In other words, when a grating line has a coincident centerline, it is optimal; if a grating line does not have a coincident centerline, a centerline with a deviation within ±80μm is selected.

[0059] When multiple centerlines are actually close to a certain theoretical distance from the first centerline, only the closest centerline is retained. In other words, when the difference between the actual distance of multiple centerlines and the theoretical distance from the first centerline is between -80μm and 80μm, only the centerline corresponding to the smallest absolute difference is retained. This ensures a one-to-one correspondence between the product's grid lines and the centerlines on the laser trace drawing.

[0060] When a theoretical distance does not have an actual distance that is equal to or close to it, it means that a certain grid line does not have a corresponding center line, and the screen is judged as defective and scrapped.

[0061] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for preparing a knotless screen printing plate, characterized in that, Includes the following steps: Step 1: Spread the mesh, wherein the warp and weft threads of the mesh are made of different materials; Step 2: Etch the mesh; Step 3: Scan the etched mesh to obtain the laser trace pattern; Step 4: Import the laser wiring pattern into the laser cutting machine, and use the laser cutting machine to cut the carrier covering the mesh to obtain a knotless mesh. In step 3, the specific steps for scanning the etched mesh and obtaining the laser routing pattern include: Step 3-1: Placing the etched mesh on a scanner for scanning, the scanner scans at least a portion of the warp threads of the mesh and generates center lines for every two adjacent warp threads; Step 3-2: Selecting and retaining the center lines corresponding to the product graphic based on the product graphic parameters, and discarding the remaining center lines; processing the retained center lines according to the product graphic to obtain the laser routing pattern; In step 3-2, the method for selecting and retaining the center line corresponding to the product graphic is as follows: Define one grid line in the product graphic as the first grid line, and the remaining grid lines have a theoretical distance from the first grid line; define a center line as the first center line, which corresponds to the first grid line; starting from the position of the first center line, measure the actual distance between the remaining center lines and the first center line in sequence; compare the multiple actual distances with the multiple theoretical distances, and retain the center line whose actual distance is equal to or closest to the theoretical distance.

2. The method for preparing a knotless screen printing plate according to claim 1, characterized in that, The difference between each actual distance and its corresponding theoretical distance is greater than or equal to -80 μm and less than or equal to 80 μm.

3. The method for preparing a knotless screen printing plate according to claim 2, characterized in that, When the difference between the actual distance of multiple centerlines and a theoretical distance is between -80μm and 80μm, the centerline corresponding to the difference with the smallest absolute value is retained.

4. The method for preparing a knotless screen printing plate according to claim 1, characterized in that, In step 2, the mesh is divided into printed and non-printed areas according to the product graphic parameters, and the warp threads in the printed area are etched.

5. The method for preparing a knotless screen printing plate according to claim 4, characterized in that, The warp threads are made of tungsten steel, and the weft threads are made of stainless steel. The etching solution I used to etch the warp threads contains H2O2 and NH4OH.

6. The method for preparing a knotless screen printing plate according to claim 4, characterized in that, The warp threads are made of stainless steel, and the weft threads are made of tungsten carbide. The etching solution II used to etch the warp threads contains FeCl3·6H2O and concentrated hydrochloric acid.

7. The method for preparing a knotless screen printing plate according to claim 1, characterized in that, In step 1, after the mesh is stretched, the direction of the polyester mesh warp is consistent with the direction of the mesh yarn warp, and the direction of the polyester mesh weft is consistent with the direction of the mesh yarn weft; the tension of the polyester mesh warp is greater than the tension of its weft.

8. A meshless screen, characterized in that, Prepared using the method described in any one of claims 1 to 7.

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