Screen printing plate and preparation method and application thereof

Abstract

The invention relates to a printing screen plate which comprises a primary printing screen plate, the primary printing screen plate is provided with an S face and a P face, the hydrophobic angle of the P face is larger than 90 degrees, the mesh number of a first metal wire mesh in the primary printing screen plate ranges from 200 meshes to 580 meshes, and the wire diameter ranges from 9 micrometers to 24 micrometers; the second metal wire mesh is arranged on the P face of the primary printing screen plate and provided with a printing pattern, and the position and the pattern of the printing pattern are the same as those of the printing pattern of the P face of the primary printing screen plate. The invention further provides a preparation method and application of the printing screen. The line width of the printing screen can be reduced to 10-12 microns, and the printing quality can be ensured, so that the solar cell adopting the printing screen has excellent conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a printing screen plate and a preparation method and application thereof. Background Art

[0002] The printing screen plate is an important tool for printing the electrodes of solar cells. Pour the paste onto the printing screen plate, and use a squeegee to drive the paste to move on the S surface of the printing screen plate, so that the paste passes through the mesh holes on the printing screen plate and is extruded onto the P surface in contact with the silicon wafer, thereby forming a corresponding pattern on the silicon wafer to form the electrodes of the solar cell.

[0003] As one of the five major elements of screen printing, the printing screen plate plays a crucial role in high-precision narrow line width screen printing. Conventional printing screen plates generally include a screen frame, a stainless steel wire mesh fixed to the bottom of the screen frame, and a polymer composite layer laminated on the stainless steel wire mesh. The polymer composite layer is processed by a laser processing technology to obtain pattern openings, achieving the effect of being able to print patterns. Among them, the thinner the line width of the printing screen plate, the less silver paste is consumed, and the higher the conversion efficiency of the solar cell. However, after reducing the line width, the ink transfer performance will become worse, and the printing difficulty will increase, and problems such as broken grids and ghost printing are likely to occur, resulting in the current line width design of the printing screen plate generally being about 15 μm and unable to be further narrowed. Summary of the Invention

[0004] Based on this, it is necessary to provide a printing screen plate and a preparation method and application thereof for the above problems. The line width of the printing screen plate can be narrowed to 10 μm - 12 μm, and the printing quality can be guaranteed, so that the solar cell using the printing screen plate has excellent conversion efficiency.

[0005] A printing screen plate, comprising:

[0006] A preliminary printing screen plate, the preliminary printing screen plate having an S surface and a P surface, the hydrophobic angle of the P surface being greater than 90°, and the mesh number of the first wire mesh in the preliminary printing screen plate being 200 - 580 meshes, and the wire diameter being 9 μm - 24 μm;

[0007] A second wire mesh, the second wire mesh being disposed on the P surface of the preliminary printing screen plate and having a printed pattern, and the printed pattern being the same as the position and pattern of the printed pattern on the P surface of the preliminary printing screen plate.

[0008] In one embodiment, the P surface has a hydrophobic film, and the hydrophobic angle of the hydrophobic film is greater than 90°.

[0009] In one embodiment, the hydrophobic film is selected from a silicon dioxide film or a copper film.

[0010] In one embodiment, the thickness of the hydrophobic film is 1 nm - 10 nm.

[0011] In one embodiment, the mesh number of the second metal wire mesh is 400 - 600 meshes, and the wire diameter is 6 μm - 12 μm.

[0012] In one embodiment, the second metal wire mesh is selected from nickel alloy wire mesh, nickel - manganese alloy wire mesh or nickel - cobalt alloy wire mesh.

[0013] A method for preparing a printing screen plate as described above, comprising the following steps:

[0014] Provide a preliminary printing screen plate, wherein the preliminary printing screen plate has an S surface and a P surface. The mesh number of the first metal wire mesh in the preliminary printing screen plate is 200 - 580 meshes, and the wire diameter is 9 μm - 24 μm. And perform a hydrophobic treatment on the P surface to make the hydrophobic angle of the P surface greater than 90°;

[0015] Set a second metal wire mesh on the P surface of the preliminary printing screen plate, and at the position on the second metal wire mesh that is the same as the printing pattern on the P surface of the preliminary printing screen plate, form a printing pattern that is the same as the P surface of the preliminary printing screen plate.

[0016] In one embodiment, an ion plating technology is used to form a hydrophobic film on the P surface of the printing screen plate, and the hydrophobic angle of the hydrophobic film is greater than 90°.

[0017] In one embodiment, an adhesive is used to bond the second metal wire mesh to the P surface of the printing screen plate at 100°C - 150°C.

[0018] An application of a printing screen plate as described above in printing the electrodes of a solar cell.

[0019] In the printing screen plate of the present invention, when the paste is extruded through the first metal wire mesh on the S surface of the preliminary printing screen plate to the P surface of the preliminary printing screen plate, due to the excellent hydrophobicity of the P surface, the paste has excellent ink - passing property, which can ensure that the printing screen plate still has excellent printing quality in the case of a narrow line width. At the same time, a second metal wire mesh is set on the P surface of the preliminary printing screen plate. When the paste passes through the hydrophobic P surface and then passes through the second metal wire mesh, it can effectively reduce the overflow of the paste and prevent problems such as widening and increased light - shielding area caused by excessive ink - passing property of the paste, thereby ensuring the line width and shaping during printing, improving the short - circuit current of the solar cell, and improving the conversion efficiency.

[0020] Therefore, through the cooperation of the hydrophobic P side of the printing screen and the second metal wire mesh, while the paste has excellent ink passing property, it can effectively prevent the overflow of the paste, enabling the line width of the printing screen to be narrowed to 10 μm - 12 μm, and ensuring the printing quality, so that the solar cell using the printing screen has excellent conversion efficiency. Description of the Drawings

[0021] Figure 1 It is a sectional view of the printing screen of the present invention.

[0022] Wherein: 1, screen frame; 2, polyester mesh; 3, first metal wire mesh; 4, polyimide film; 5, wire groove; 6, hydrophobic film; 7, second metal wire mesh; 8, tape. Detailed Embodiments

[0023] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. The optional range of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or all related listed items.

[0025] As Figure 1 shown, a printing screen according to an embodiment provided by the present invention includes a preliminary printing screen and a second metal wire mesh 7. It should be noted that the preliminary printing screen is the traditional printing screen, which has an S side and a P side. The difference is that the hydrophobic angle of the P side of the traditional printing screen is generally less than 90°, while the P side of the preliminary printing screen of the present invention is hydrophobically treated, and the hydrophobic angle is greater than 90°. And the mesh number of the first metal wire mesh 3 in the preliminary printing screen is limited to 200 - 580 meshes, and the wire diameter is 9 μm - 24 μm; and the second metal wire mesh 7 is disposed on the P side of the preliminary printing screen and is provided with a printing pattern, and the printing pattern is the same as the position and pattern of the printing pattern on the P side of the preliminary printing screen.

[0026] In the printing screen plate of the present invention, when the paste is extruded through the first metal wire mesh 3 on the S surface of the preliminary printing screen plate to the P surface of the preliminary printing screen plate, due to the excellent hydrophobicity of the P surface, the paste has excellent ink passing properties, which can ensure excellent printing quality of the printing screen plate even in the case of a narrow line width. At the same time, a second metal wire mesh 7 is provided on the P surface of the preliminary printing screen plate. When the paste passes through the hydrophobic P surface and then passes through the second metal wire mesh 7, it can effectively reduce the overflow of the paste and prevent problems such as broadening and increased light shielding area caused by excessive ink passing properties of the paste, thereby ensuring the line width and shaping during printing, improving the short-circuit current of the solar cell, and improving the conversion efficiency.

[0027] Therefore, through the cooperation of the hydrophobic P surface of the printing screen plate and the second metal wire mesh 7, the paste has excellent ink passing properties while effectively preventing the overflow of the paste, enabling the line width of the printing screen plate to be narrowed to 10 μm - 12 μm, and ensuring printing quality, so that the solar cell using the printing screen plate has excellent conversion efficiency.

[0028] The present invention does not specifically limit the type or structure of the preliminary printing screen plate. Preferably, a non-photosensitive screen plate is used. The non-photosensitive screen plate includes a screen frame 1, a polyester mesh 2 fixed to the bottom of the screen frame 1, a first metal wire mesh 3, and a polyimide film 4. The polyimide film 4 is provided with a plurality of wire grooves 5, and the wire grooves 5 form a printing pattern. Optionally, the first metal wire mesh 3 is selected from at least one of a tungsten steel alloy wire mesh, a stainless steel alloy wire mesh, or a nickel alloy wire mesh.

[0029] Different from the preliminary printing screen plate, the hydrophobic angle of the P surface of the printing screen plate of the present invention is greater than 90°. Generally, the way of changing the microscopic structure of the object surface can be adopted, such as forming a micro- or nano-level uneven surface, or forming a uniform and dense hydrophobic coating on the object surface to make the hydrophobic angle of the object surface greater than 90°.

[0030] Optionally, the present invention preferably provides a hydrophobic film 6 on the P surface of the preliminary printing screen plate, and the hydrophobic angle of the hydrophobic film 6 is greater than 90°. Specifically, the hydrophobic film 6 can be attached to the surface of the polyimide film 4 on the P surface, the side walls of the wire grooves 5, and the wire diameters of the first metal wire mesh 3, and does not block the mesh holes of the first metal wire mesh 3 and the wire grooves 5. Thus, it is ensured that the paste can be smoothly extruded to the P surface of the printing screen plate, and when the paste flows through the wire grooves 5, the wire grooves 5 have excellent hydrophobicity, so that the paste has excellent ink passing properties.

[0031] Optionally, a hydrophobic film may also be provided on the S surface of the printing stencil, and the hydrophobic film adheres to the wire diameter of the first wire mesh 3 on the S surface and does not block the mesh holes of the first wire mesh 3 on the S surface. Thus, both the S surface and the P surface of the printing stencil have hydrophobic films, which can further improve the ink passing property of the slurry when the slurry is extruded from the S surface to the P surface of the printing stencil.

[0032] Optionally, the hydrophobic angle of the hydrophobic film is preferably 90°-120°.

[0033] Optionally, the hydrophobic film 6 is preferably a silica film or a copper film.

[0034] Optionally, the thickness of the hydrophobic film 6 is preferably 1nm-10nm. Since the width of the wire groove 5 is 10μm-20μm, the extremely thin hydrophobic film 6 does not affect the width of the wire groove 5. When the slurry is extruded into the wire groove 5 to form a printing pattern, it does not affect the printing quality. At the same time, the hydrophobic film 6 can also improve the smoothness of the P surface of the printing stencil, thereby reducing the friction between the slurry and the wire groove 5 and further improving the ink passing property of the slurry.

[0035] Optionally, the second wire mesh 7 is bonded to the surface of the polyimide film 4 facing away from the P surface of the initial printing stencil through an adhesive, so that when the slurry flows through the wire groove 5, the problem of slurry broadening caused by too good ink passing property can be avoided, and effective plasticity of the slurry can be achieved.

[0036] Optionally, the second wire mesh 7 is preferably at least one of a nickel alloy wire mesh, a nickel-manganese alloy wire mesh or a nickel-cobalt alloy wire mesh.

[0037] Optionally, the mesh number of the second wire mesh 7 is preferably 200 mesh-600 mesh, and the wire diameter is preferably 6μm-24μm. Further preferably, the mesh number is 400 mesh-600 mesh, and the wire diameter is 6μm-12μm, so as to further make the printing pattern clear, narrow the line width and improve the conversion efficiency.

[0038] Optionally, the thickness of the second wire mesh 7 is preferably 6μm-10μm, so as to be more conducive to preventing slurry overflow and further ensuring that the printing stencil can achieve a narrow line width.

[0039] The present invention also provides a method for preparing a printing stencil, including the following steps:

[0040] S1, providing an initial printing stencil, wherein the initial printing stencil has an S surface and a P surface, the mesh number of the first wire mesh 3 in the initial printing stencil is 200 mesh-580 mesh, the wire diameter is 9μm-24μm, and a hydrophobic treatment is performed on the P surface to make the hydrophobic angle of the P surface greater than 90°;

[0041] S2. Set a second metal wire mesh 7 on the P side of the initial printing screen plate, and form a printing pattern identical to that on the P side of the initial printing screen plate at the position on the second metal wire mesh 7 that is the same as the printing pattern on the P side of the initial printing screen plate.

[0042] In step S1, an existing initial printing screen plate can be directly provided, or an initial printing screen plate can be prepared as needed. For example, the initial printing screen plate can be prepared with reference to the following steps:

[0043] S11. Fix the polyester mesh 2 to the bottom of the screen frame 1 to determine the tension.

[0044] S12. Bond the first metal wire mesh 3 with a mesh count of 200 - 580 meshes and a wire diameter of 9μm - 24μm to the polyester mesh 2 and fix it to the screen frame 1.

[0045] S13. Thermally press - bond the polyimide film 4 to the first metal wire mesh 3 and form a printing pattern on the polyimide film 4.

[0046] Before step S12, the first metal wire mesh 3 can also be pretreated to remove oxides and excess impurities on the surface of the first metal wire mesh 3.

[0047] In step S12, the method of bonding the first metal wire mesh 3 to the polyester mesh 2 is not specifically limited. Preferably, the first metal wire mesh 3 is press - ironed and bonded to the screen frame 1 using uv glue. The press - ironing temperature is preferably 250°C - 350°C, and the time is preferably 2min - 4min to avoid the polyester mesh 2 from melting and shrinking due to high temperature or long press - ironing time. Repeat twice and let it stand for 8h - 12h.

[0048] Optionally, after the first metal wire mesh 3 is fixed to the screen frame 1, 3 - 5 wire meshes of the first metal wire mesh 3 can be ablated to facilitate laser alignment during the formation of the printing pattern on the polyimide film 4 later, and then the residue on the surface of the first metal wire mesh 3 after laser engraving is cleaned.

[0049] In step S13, the polyimide film 4 and the drawn - out first metal wire mesh 3 are press - ironed and bonded using an industrial press - ironing machine. The time is preferably 10min - 20min, the temperature is preferably 100°C - 300°C, and let it stand for 8h - 10h after press - ironing.

[0050] Then, laser alignment is performed using a film paper, and a preset pattern is engraved onto the polyimide film 4 using a lithography machine to form a wire groove 5. The wire groove 5 forms a printing pattern, and the initial printing screen plate in step S1 is obtained.

[0051] Optionally, the hydrophobic film is formed on the P side of the initial printing screen plate using an ion plating technique.

[0052] In step S2, a second metal wire mesh 7 is formed on the surface of the polyimide film 4 facing away from the P side of the initial printing screen plate. The second metal wire mesh 7 and the polyimide film 4 are adhesively bonded at a high temperature using an adhesive. After bonding, it is left standing for a period of time. The preset pattern is engraved onto the second metal wire mesh 7 using a laser, and the residues after laser engraving are washed with pure water to form a printing pattern identical to that of the polyimide film 4. Preferably, the bonding temperature is 100°C - 150°C, the bonding time is 2 min - 4 min, and the standing time is 6 h - 8 h.

[0053] Optionally, before bonding the second metal wire mesh 7 to the polyimide film 4, the second metal wire mesh 7 can also be cleaned. For example, it is soaked in a mixed solution of hydrogen peroxide and sodium hydroxide for 15 min - 20 min to remove organic impurities on the second metal wire mesh 7, then soaked in a mixed solution of hydrofluoric acid and hydrochloric acid for 5 min - 10 min to remove excess metal impurities, and finally rinsed with pure water for 10 min - 15 min.

[0054] Optionally, a tape 8 can also be selected to be pasted on the surface of the polyester mesh 2 facing away from the S side to fix the tension of the printing screen plate, which is beneficial for better protecting the screen plate. The tape 8 is preferably silver dragon paper.

[0055] The present invention also provides an application of the printing screen plate in printing the electrodes of a solar cell. For example, the printing screen plate is used for screen printing to prepare the positive and negative electrodes of a solar cell.

[0056] Hereinafter, the printing screen plate, its preparation method and application will be further described through the following specific examples.

[0057] Example 1

[0058] The polyester mesh is adhered to the bottom of the screen frame to determine the tension, ensuring the integrity of the appearance of the non-printing area. A tungsten carbide alloy wire mesh with 480 meshes and a wire diameter of 11 μm is press-bonded and fixed to the screen frame with the polyester mesh. Among them, the hot pressing temperature is 250°C and the time is 2 min. After repeating twice, it is left standing for 8 h; 3 wire meshes of the tungsten carbide alloy wire mesh are laser ablated using a lithography machine, and the residues on its surface after laser engraving are washed; the polyimide film and the tungsten carbide alloy wire mesh are press-bonded, among which the temperature is 100°C and the time is 10 min, and it is left standing for 8 h; laser alignment is performed using a film drawing paper, and a preset pattern is engraved onto the polyimide film using a lithography machine to form a printing pattern, obtaining an initial printing screen plate.

[0059] On the P side of the initial printed stencil, in a vacuum environment, high-voltage gas discharge vaporizes and ionizes the plating material and deposits it on the polyimide film, coating a silica hydrophobic film. Among them, the thickness of the hydrophobic film is 5 nm and the contact angle is 100°; soak a nickel alloy wire mesh with a thickness of 6 μm, 500 meshes, and a wire diameter of 9 μm in a sodium hydroxide solution with a concentration of 41% for 15 min, then soak it in a mixed solution of hydrochloric acid and hydrofluoric acid for 5 min, rinse it with pure water for 10 min, press and iron it with the polyimide film at 100 °C for 2 min, and after standing for 6 h, use a lithography machine to engrave the printing pattern at the same position on the nickel alloy wire mesh as on the polyimide film, rinse it with pure water, then paste silver dragon paper for protection, and fix the stencil tension to obtain the printed stencil. The line width of the printed stencil in this embodiment is 12 μm.

[0060] Example 2

[0061] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 200 meshes and a wire diameter of 24 μm to the polyester mesh and fix it to the screen frame. Among them, the hot pressing temperature is 250 °C and the time is 2 min. After repeating twice, let it stand for 8 h; use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residues on its surface after laser engraving; press and bond the polyimide film to the tungsten steel alloy wire mesh. Among them, the temperature is 100 °C and the time is 10 min, and let it stand for 8 h; perform laser alignment with a film drawing paper, and use a lithography machine to engrave the preset pattern on the polyimide film to form a printing pattern to obtain the initial printed stencil.

[0062] On the P side of the initial printed stencil, in a vacuum environment, high-voltage gas discharge vaporizes and ionizes the plating material and deposits it on the polyimide film, coating a silica hydrophobic film. Among them, the thickness of the hydrophobic film is 5 nm and the contact angle is 100°; soak a nickel alloy wire mesh with a thickness of 6 μm, 400 meshes, and a wire diameter of 12 μm in a sodium hydroxide solution with a concentration of 41% for 15 min, then soak it in a mixed solution of hydrochloric acid and hydrofluoric acid for 5 min, rinse it with pure water for 10 min, press and iron it with the polyimide film at 100 °C for 2 min, and after standing for 6 h, use a lithography machine to engrave the printing pattern at the same position on the nickel alloy wire mesh as on the polyimide film, rinse it with pure water, then paste silver dragon paper for protection, and fix the stencil tension to obtain the printed stencil of the present invention. The line width of the printed stencil in this embodiment is 12 μm.

[0063] Example 3

[0064] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 580 meshes and a wire diameter of 9 μm to the polyester mesh and fix it to the screen frame. The ironing temperature is 250 °C and the time is 2 min. Repeat twice and then let it stand for 8 h. Use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residues on its surface after laser engraving. Press and bond the polyimide film to the tungsten steel alloy wire mesh. The temperature is 100 °C and the time is 10 min. Let it stand for 8 h. Perform laser alignment with a film drawing paper and use a lithography machine to engrave a preset pattern on the polyimide film to form a printed pattern, obtaining a preliminary printed screen plate.

[0065] On the P side of the preliminary printed screen plate, in a vacuum environment, high-voltage gas discharge evaporates and ionizes the plating material and deposits it on the polyimide film to coat a hydrophobic silicon dioxide film. The thickness of the hydrophobic film is 5 nm and the contact angle is 100°. Immerse a nickel alloy wire mesh with a thickness of 6 μm, 600 meshes, and a wire diameter of 6 μm in a sodium hydroxide solution with a concentration of 41% for 15 min, then immerse it in a mixed solution of hydrochloric acid and hydrofluoric acid for 5 min, rinse it with pure water for 10 min, press and bond it to the polyimide film at 100 °C for 2 min, let it stand for 6 h, and then use a lithography machine to engrave the printed pattern at the same position as the polyimide film on the nickel alloy wire mesh. After rinsing with pure water, paste a silver dragon paper for protection, fix the screen plate tension, obtaining the printed screen plate of the present invention. The line width of the printed screen plate in this embodiment is 12 μm.

[0066] Example 4

[0067] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 480 meshes and a wire diameter of 11 μm to the polyester mesh and fix it to the screen frame. The ironing temperature is 250 °C and the time is 2 min. Repeat twice and then let it stand for 8 h. Use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residues on its surface after laser engraving. Press and bond the polyimide film to the tungsten steel alloy wire mesh. The temperature is 100 °C and the time is 10 min. Let it stand for 8 h. Perform laser alignment with a film drawing paper and use a lithography machine to engrave a preset pattern on the polyimide film to form a printed pattern, obtaining a preliminary printed screen plate;

[0068] On the P side of the initial printed stencil, in a vacuum environment, high-voltage gas discharge evaporates and ionizes the plating material and deposits it on the polyimide film, coating a silica hydrophobic film. Among them, the thickness of the hydrophobic film is 5 nm, and the contact angle is 100°. Immerse a nickel alloy wire mesh with a thickness of 6 μm, 600 meshes, and a wire diameter of 6 μm in a sodium hydroxide solution with a concentration of 41% for 15 min, then immerse it in a mixed solution of hydrochloric acid and hydrofluoric acid for 5 min, rinse it with pure water for 10 min, press and iron it with the polyimide film at 100 °C for 2 min, let it stand for 6 h, and then use a lithography machine to engrave the printing pattern at the same position on the nickel alloy wire mesh and the polyimide film. After rinsing with pure water, paste a silver dragon paper for protection, fix the stencil tension, and obtain the printed stencil of the present invention. The line width of the printed stencil in this embodiment is 12 μm.

[0069] Comparative Example 1

[0070] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 480 meshes and a wire diameter of 11 μm to the polyester mesh and fix it to the screen frame. Among them, the hot pressing temperature is 250 °C and the time is 2 min. After repeating twice, let it stand for 8 h; use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residue on its surface after laser engraving; press and bond the polyimide film to the tungsten steel alloy wire mesh. Among them, the temperature is 100 °C and the time is 10 min. Let it stand for 8 h; perform laser alignment with a film drawing paper, and use a lithography machine to engrave the preset pattern on the polyimide film to form a printing pattern, obtaining the initial printed stencil. The line width of the initial printed stencil in this comparative example is 12 μm.

[0071] Comparative Example 2

[0072] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 480 meshes and a wire diameter of 11 μm to the polyester mesh and fix it to the screen frame. Among them, the hot pressing temperature is 250 °C and the time is 2 min. After repeating twice, let it stand for 8 h; use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residue on its surface after laser engraving; press and bond the polyimide film to the tungsten steel alloy wire mesh. Among them, the temperature is 100 °C and the time is 10 min. Let it stand for 8 h; perform laser alignment with a film drawing paper, and use a lithography machine to engrave the preset pattern on the polyimide film to form a printing pattern, obtaining the initial printed stencil.

[0073] On the P side of the initial printed stencil, in a vacuum environment, high-voltage gas discharge evaporates and ionizes the plating material and deposits it on the polyimide film, coating a silica hydrophobic film. Among them, the thickness of the hydrophobic film is 5 nm, and the contact angle is 100°. The line width of the printed stencil in this comparative example is 12 μm.

[0074] Comparative Example 3

[0075] Adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 480 meshes and a wire diameter of 11 μm to the polyester mesh and fix it to the screen frame. The ironing temperature is 250 °C and the time is 2 min. After repeating twice, let it stand for 8 h. Use a lithography machine to laser ablate 3 wire meshes of the tungsten steel alloy wire mesh and clean the residues after laser engraving on its surface. Press and bond the polyimide film to the tungsten steel alloy wire mesh. Among them, the temperature is 100 °C and the time is 10 min. Let it stand for 8 h. Perform laser alignment with a film drawing paper, and use a lithography machine to engrave a preset pattern on the polyimide film to form a printed pattern, thus obtaining a preliminary printed screen plate.

[0076] Immerse a nickel alloy wire mesh with a thickness of 6 μm, 500 meshes, and a wire diameter of 9 μm in a sodium hydroxide solution with a concentration of 41% for 15 min, then immerse it in a mixed solution of hydrochloric acid and hydrofluoric acid for 5 min, rinse it with pure water for 10 min, and press and iron it with the polyimide film at 100 °C for 2 min. After standing for 6 h, use a lithography machine to engrave the printed pattern at the same position on the nickel alloy wire mesh as on the polyimide film. After rinsing with pure water, paste a silver dragon paper for protection and fix the screen plate tension to obtain the printed screen plate of the present invention. The line width of the printed screen plate in this embodiment is 12 μm.

[0077] Comparative Example 4

[0078] The difference between Comparative Example 4 and Example 1 is that: adhere the polyester mesh to the bottom of the screen frame to determine the tension and ensure the integrity of the appearance of the non-printing area. Press and bond a tungsten steel alloy wire mesh with 600 meshes and a wire diameter of 6 μm to the polyester mesh and fix it to the screen frame. The line width of the printed screen plate in this comparative example is 12 μm.

[0079] The performance of the solar cells obtained by using the printed screen plates in the above examples and comparative examples is shown in Table 1.

[0080] Table 1

[0081] Uoc Isc FF Eta Poor printing Example 1 0.6990 13.638 81.32 23.48％ 0.33％ Example 2 0.6988 13.631 81.27 23.45％ 0.52％ Example 3 0.6987 13.633 81.28 23.45％ 0.55％ Example 4 0.6988 13.631 81.28 23.46％ 0.47％ Comparative Example 1 0.6985 13.608 81.30 23.41％ 1.05％ Comparative Example 2 0.6984 13.605 81.29 23.40％ 0.47％ Comparative Example 3 0.6986 13.630 81.24 23.43％ 1.10％ Comparative Example 4 0.6985 13.631 81.25 23.43％ 0.64％

[0082] As can be seen from Table 1, although the line widths of the printed screen plates in Comparative Examples 1-4 can also reach 12 μm, but after reducing the line width, the ink transfer performance during printing becomes poor and the printing difficulty increases. As a result, the printing defect ratio of the manufactured solar cells is high and the solar energy conversion efficiency is low. While in Examples 1-4, a hydrophobic film and a second metal wire mesh are added to the conventional plate-making process, so that the line width of the printed screen plate can be narrowed to 10 μm - 12 μm, and the printing quality can be ensured, the printing defect ratio can be reduced, and at the same time, the conversion efficiency of the solar cells can be improved.

[0083] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0084] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A printing screen plate, characterized in that, it includes: A primary printing screen plate, the primary printing screen plate has an S surface and a P surface, the hydrophobic angle of the P surface is greater than 90°, and the mesh number of the first metal wire mesh in the primary printing screen plate is 200 mesh - 580 mesh, and the wire diameter is 9μm - 24μm; A second metal wire mesh, the second metal wire mesh is arranged on the P surface of the primary printing screen plate, and a printing pattern is arranged, and the position and pattern of the printing pattern are the same as those of the printing pattern on the P surface of the primary printing screen plate.

2. The printing screen plate according to claim 1, characterized in that, the P surface has a hydrophobic film, and the hydrophobic angle of the hydrophobic film is greater than 90°.

3. The printing screen plate according to claim 2, characterized in that, the hydrophobic film is selected from a silicon dioxide film or a copper film.

4. The printing screen plate according to claim 2, characterized in that, the thickness of the hydrophobic film is 1nm - 10nm.

5. The printing screen plate according to claim 1, characterized in that, the mesh number of the second metal wire mesh is 400 mesh - 600 mesh, and the wire diameter is 6μm - 12μm.

6. The printing screen plate according to claim 1, characterized in that, the second metal wire mesh is selected from a nickel alloy wire mesh, a nickel - manganese alloy wire mesh or a nickel - cobalt alloy wire mesh.

7. A preparation method of a printing screen plate according to any one of claims 1 - 6, characterized in that, it includes the following steps: Provide a primary printing screen plate, wherein the primary printing screen plate has an S surface and a P surface, the mesh number of the first metal wire mesh in the primary printing screen plate is 200 mesh - 580 mesh, and the wire diameter is 9μm - 24μm, and perform hydrophobic treatment on the P surface to make the hydrophobic angle of the P surface greater than 90°; Arrange a second metal wire mesh on the P surface of the primary printing screen plate, and at the position on the second metal wire mesh that is the same as the printing pattern on the P surface of the primary printing screen plate, form a printing pattern that is the same as the printing pattern on the P surface of the primary printing screen plate.

8. The preparation method of a printing screen plate according to claim 7, characterized in that, Use ion plating technology to form a hydrophobic film on the P surface of the printing screen plate, and the hydrophobic angle of the hydrophobic film is greater than 90°.

9. The preparation method of a printing screen plate according to claim 7, characterized in that, Use an adhesive to bond the second metal wire mesh to the P surface of the printing screen plate at 100°C - 150°C.

10. An application of a printing screen plate according to any one of claims 1 - 6 in printing electrodes of a solar cell.

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