A printing screen and a method for manufacturing a printing screen

Abstract

The application relates to the field of screen printing, and provides a printing screen and a preparation method of the printing screen. The printing screen provided by the application comprises a base screen, the base screen comprises steel wire lines; a functional layer is arranged on the surface of the base screen, the material of the functional layer comprises metal and diamond, and the metal comprises at least one of nickel or cobalt. The printing screen provided by the application still has good wear resistance and tension stability during long-term high-speed printing, and has good compatibility with new slurry.

Description

Technical Field

[0001] This application relates to the field of screen printing, and in particular to a printing screen and a method for preparing the printing screen. Background Technology

[0002] Screen printing is a key process in the fabrication of metal electrodes for crystalline silicon solar cells. The printing screen, as the core consumable material in this process, directly determines the morphology, aspect ratio, and conductivity of the electrodes, thus affecting the conversion efficiency and yield of the solar cells.

[0003] Traditional printing screens, while possessing high strength and toughness, suffer from insufficient wear resistance, poor tension stability, and are prone to incompatibility issues with new printing pastes. Summary of the Invention

[0004] This application provides a printing screen and a method for preparing the printing screen. The printing screen still has good wear resistance and tension stability, at least during long-term high-speed printing, and has good compatibility with new pastes.

[0005] The first aspect of this application provides a printing screen, comprising: a substrate mesh, the substrate mesh including steel wires; and a functional layer disposed on the surface of the substrate mesh, the functional layer being made of metal and diamond, the metal including at least one of nickel or cobalt.

[0006] In one possible implementation, the thickness of the functional layer is 2μm to 15μm.

[0007] In one possible implementation, the metal and diamond are evenly distributed.

[0008] In one possible implementation, the functional layer consists of a metal layer and a diamond layer, with the metal layer and diamond layer alternating between the two.

[0009] In one possible implementation, the diamond mass content is 15% to 35% based on the quality of the functional layer; and / or, the equivalent particle size of the diamond is 1 μm to 5 μm.

[0010] In one possible implementation, the diameter of the steel wire is 15μm to 25μm.

[0011] In one possible implementation, the steel wire is made of high-carbon steel or stainless steel alloy.

[0012] In one possible implementation, the carbon content in the high-carbon steel is 0.5% to 0.8% by mass; the stainless steel alloy includes molybdenum, niobium, and nitrogen, and the tensile strength of the stainless steel alloy is not less than 1500 MPa.

[0013] The second aspect of this application also provides a method for preparing a printing screen, comprising the following steps: weaving steel wires into a substrate mesh, and then depositing a functional layer on the surface of the substrate mesh using an electrochemical deposition method or a physical vapor deposition method; the material of the functional layer includes metal and diamond, and the metal includes at least one of nickel or cobalt.

[0014] In one possible implementation, depositing a functional layer on the surface of a substrate mesh using electrochemical deposition includes the following steps: placing the substrate mesh in an electroplating solution, using the substrate mesh as a cathode, and electroplating the functional layer on the surface of the substrate mesh; the electroplating solution includes diamond powder and metal ions, the metal ions including at least one of nickel ions or cobalt ions; and the surface of the diamond powder is covered with a conductive metal.

[0015] In one possible implementation, the current density during electroplating is 1 A / dm³. 2 ~3A / dm 2 The temperature is 50℃~60℃.

[0016] In one possible implementation, depositing a functional layer on the surface of a substrate mesh using physical vapor deposition includes the following steps: using magnetron sputtering technology, diamond and metal are sequentially sputtered onto the surface of the substrate layer to form alternating diamond and metal layers, all of which form the functional layer.

[0017] In one possible implementation, after depositing the functional layer, the material is further heat-treated at 150℃~250℃ for 1h~2h.

[0018] The technical solution provided in this application has at least the following advantages: In this application, the steel wires in the substrate mesh provide the core mechanical strength and tension foundation for the printing screen, ensuring its normal operation. The functional layer on the surface of the substrate mesh includes metals and diamond. Diamond possesses excellent hardness and wear resistance, enhancing the wear resistance of the printing screen. Metals such as nickel and cobalt provide a smooth and chemically stable surface, effectively reducing ink residue and adhesion during printing. This allows for good compatibility with new inks such as low-temperature inks and lead-free inks, improving printing uniformity and electrode aspect ratio. Furthermore, the functional layer on the substrate mesh surface also acts as a reinforcing layer, working in conjunction with the inherently creep-resistant steel wires to further enhance the overall creep resistance of the printing screen. This significantly suppresses tension decay during long-term use, thereby improving the tension stability of the printing screen after prolonged high-speed use. Therefore, the printing screen in this embodiment exhibits good wear resistance, maintains good tension stability even after long-term high-speed printing, and is well-compatible with new inks. Its lifespan and printing yield can be significantly improved, thereby reducing the cost of printing screens per unit of battery cell and having excellent economic value. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating the preparation process of the printing screen in an embodiment of this application. Detailed Implementation

[0021] As is known from the background art, existing printing screens suffer from insufficient wear resistance and poor tension stability after repeated high-speed printing. Furthermore, existing printing screens are prone to incompatibility with new printing pastes. The inventors have discovered the reasons for these problems as follows: Most existing printing screens are made of stainless steel (SUS). During high-speed printing, the continuous friction between the squeegee and the printing screen causes premature wear, changes in mesh size, affecting printing accuracy and consistency, shortening the screen's lifespan, and resulting in insufficient wear resistance. Stainless steel is prone to creep and plastic deformation under repeated tension and printing pressure, leading to rapid tension decay and poor tension stability. Furthermore, with the development of new conductive pastes such as low-temperature silver paste and lead-free pastes, their corrosiveness and adhesion to printing screens differ. Stainless steel printing screens often cannot adequately meet the adhesion and corrosion resistance requirements of these new pastes.

[0022] Based on this, this application provides a printing screen and a method for preparing the printing screen. In the printing screen of this application, steel wire is used as the base mesh, and metal and diamond are used as functional layers, so that the printing screen of this application has good wear resistance and tension stability, and can be well compatible with new pastes.

[0023] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0026] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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 limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] In the description of embodiments of this application, the terms "about," "approximately," "roughly," or "about" for referring to a specific parameter include numerical values, and those skilled in the art will understand that the deviation from the numerical value is within the acceptable tolerance of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0029] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0030] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" may refer to a layer, film, region, portion, structure, etc.

[0031] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0033] This application provides a printing screen, including a substrate mesh comprising steel wires; a functional layer is disposed on the surface of the substrate mesh, the material of the functional layer including metal and diamond, the metal including at least one of nickel or cobalt.

[0034] In this embodiment, the steel wires in the substrate mesh provide the core mechanical strength and tension foundation for the printing screen, ensuring its normal operation. The functional layer on the surface of the substrate mesh includes metals and diamond. Diamond possesses excellent hardness and wear resistance, enhancing the wear resistance of the printing screen. Metals such as nickel and cobalt provide a smooth and chemically stable surface, effectively reducing ink residue and adhesion during printing. This layer is also compatible with new inks such as low-temperature inks and lead-free inks, improving printing uniformity and electrode aspect ratio. Furthermore, the functional layer on the substrate mesh surface also acts as a reinforcing layer. Working in conjunction with the steel wires, which have excellent creep resistance, it further enhances the overall creep resistance of the printing screen, significantly suppressing tension decay during long-term use and improving tension stability after prolonged high-speed use. Therefore, the printing screen in this embodiment exhibits good wear resistance, maintains good tension stability after long-term high-speed printing, and is well-compatible with new inks. Its lifespan and printing yield can be significantly improved, thereby reducing the cost of printing screens per unit of battery cell and having excellent economic value.

[0035] This application does not have specific requirements regarding the material of the steel wire, as long as it meets the purpose of this application. For example, high-carbon steel or ultra-high-strength stainless steel alloy can be used. Specifically, the carbon mass percentage of high-carbon steel is typically in the range of 0.5% to 0.8%, while ultra-high-strength stainless steel alloy generally contains molybdenum, niobium, and nitrogen, and its tensile strength is not less than 1500 MPa. Both high-carbon steel wire and ultra-high-strength stainless steel alloy can well meet the requirements of this application for providing the core mechanical strength and tensile foundation for the matrix mesh.

[0036] In addition, in some embodiments of this application, the diameter of the steel wire is typically in the range of 15μm to 25μm. Within this range, the mesh size and dimensions of the resulting matrix mesh can well meet the requirements of the printing screen.

[0037] In some embodiments of this application, to balance the wear resistance and tension stability of the printing screen, the diamond content typically accounts for 15% to 35% of the functional layer's mass. This is because when the diamond content is below 15%, the hard, wear-resistant phase in the functional layer is insufficient, limiting the improvement in wear resistance; when it is above 35%, the spacing between diamond particles is too small, making it difficult for the nickel-cobalt metal matrix to effectively encapsulate and fix them, causing the diamond particles to easily detach during printing friction. Simultaneously, the internal stress of the functional layer increases, affecting the screen's tension stability. Controlling the diamond content within the range of 15% to 35% ensures sufficient wear resistance while maintaining the structural integrity of the functional layer and good tension retention.

[0038] In some embodiments of this application, the equivalent particle size of diamond is typically 1 μm to 5 μm. "Equivalent particle size" refers to the diameter of a spherical particle used to represent the actual particle's diameter when a particle's physical properties (such as volume, settling velocity, etc.) are the same as or similar to those of a homogeneous spherical particle. If the equivalent particle size of diamond is too small, the diamond particles are too fine and prone to agglomeration, making uniform dispersion difficult during electrochemical deposition. This results in uneven diamond distribution in the coating and reduced local wear resistance. Furthermore, excessively fine particles have limited effect on improving the coating's hardness. If the equivalent particle size of diamond is too large, it may clog the screen mesh, affecting printing accuracy. Additionally, its protrusion relative to the surface of the functional layer makes it prone to being pulled out entirely during friction, accelerating functional layer failure. By controlling the equivalent particle size of diamond within the range of 1μm to 5μm, it is possible to ensure good dispersion and co-deposition uniformity of diamond, and to form an effective wear-resistant hard phase, thereby significantly improving the wear resistance life of the screen without clogging the mesh.

[0039] In this embodiment, the metal in the functional layer can form a metal layer, and the diamond can form a diamond layer. The metal layer and diamond are then alternately arranged to constitute the functional layer. This structure has the following advantages: First, numerous interlayer interfaces effectively hinder crack propagation and improve the fatigue resistance of the functional layer; second, by adjusting the single-layer thickness and the number of stacking cycles, the matching of hardness and toughness can be flexibly optimized; third, the functional layer has low internal stress and strong bonding, exhibiting superior stability during long-term high-frequency printing. This structure is suitable for applications requiring high lifespan and high precision.

[0040] In some embodiments of this application, metal and diamond can also be uniformly mixed to form a functional layer. In this structure, diamond particles are dispersed in a nickel-cobalt-based metal matrix, forming an "island-sea" structure. The preparation process is mature and the cost is low. Moreover, the uniform distribution of diamond particles can provide all-round wear-resistant protection, which is suitable for conventional printing needs.

[0041] The functional layers with the two different configurations can be prepared using different methods, which will be described in detail later in this application.

[0042] In some embodiments of this application, the thickness of the functional layer is 5μm to 15μm, which balances abrasion resistance and printing accuracy. If the functional layer is too thin, it is easily worn through during long-term printing, failing to provide continuous and effective protection for the substrate layer, thus limiting the improvement of screen life. If the functional layer is too thick, the excessively thick functional layer will fill and reduce the opening area of ​​the screen, affecting the permeability of the ink and the printing morphology of the electrodes. At the same time, it increases the internal stress of the functional layer, which may lead to a decrease in the tension of the printing screen or even brittle breakage of the wires. Controlling the thickness of the functional layer within the range of 5μm to 15μm provides sufficient abrasion resistance to significantly extend the service life of the printing screen while maintaining the original mesh geometry of the screen, ensuring printing accuracy and consistency.

[0043] Accordingly, another embodiment of this application also provides a method for preparing a printing screen, which can be used to prepare the printing screen provided in the above embodiments, and its preparation process flow diagram is as follows. Figure 1 As shown in the accompanying drawings, the preparation method of a printing screen according to another embodiment of this application will be described in detail below with reference to the accompanying drawings. For the parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding description of the foregoing embodiment, and will not be described in detail below.

[0044] The method for preparing a printing screen according to the embodiments of this application includes the following steps: S100, Weave steel wires into a base mesh.

[0045] This step typically involves first drawing the raw material into threads using a wire drawing process, and then weaving them into a base web. The raw material can be high-carbon steel or ultra-high-strength stainless steel alloy, etc. The resulting base web is usually in the form of a plain weave or satin weave. Both "plain weave" and "satin weave" are fabric structures. Plain weave is a basic fabric structure formed by alternating warp and weft yarns in a 1:1 ratio, belonging to one of the three basic weave structures of woven fabrics. Its structural repeat number is 2, with each yarn interlacing with an adjacent yarn once, resulting in a similar appearance on both sides and a dense interlacing pattern. Satin weave has longer warp or weft floats, and the interlacing points are regularly spaced, forming a smooth and uniform surface. Its minimum complete structure requires at least five warp and weft yarns, and the parameters must satisfy R≥5 and be coprime to the fly number S.

[0046] After the substrate mesh is woven, it is generally cleaned to remove oil and oxide layers from its surface, ensuring a clean surface for subsequent deposition of functional layers. This application does not specify a particular cleaning method; it can be at least one of ultrasonic cleaning, alkaline cleaning, or acid cleaning, as long as it meets the objectives of this application.

[0047] S200, Deposit a functional layer on the surface of the substrate mesh using electrochemical deposition or physical vapor deposition.

[0048] In this step, the functional layer can be prepared by electrochemical deposition or physical vapor deposition (PVD), corresponding to the two different functional layer structures described above. Electrochemical deposition produces a functional layer with uniformly distributed diamond and metal, while PVD produces a functional layer with alternating layers of diamond and metal. These will be explained in detail below.

[0049] The functional layer was deposited on the surface of the substrate mesh using electrochemical deposition as follows: First, a substrate mesh is placed in an electroplating solution. Then, using the substrate mesh as a cathode, a functional layer is electroplated and deposited on its surface. During the electroplating process, the raw materials in the electroplating solution are deposited on the surface of the substrate mesh, thus forming the functional layer. Therefore, the electroplating solution contains the components of the functional layer, namely, diamond powder and metal ions, wherein the metal ions include at least one of nickel ions or cobalt ions. As electroplating proceeds, nickel particles and cobalt ions gain electrons at the cathode, thereby reducing to elemental form and depositing on the cathode surface. Diamond powder also co-deposits with the metal ions, resulting in a uniform distribution of metal and diamond powder in the obtained functional layer. Since diamond is non-conductive, the surface of the diamond powder in the electroplating solution is covered with a conductive metal to ensure that the diamond powder can be deposited on the cathode under the influence of current. This application does not particularly limit the type of conductive technology, as long as it meets the purpose of this application; typically, to avoid introducing other metal impurities, the conductive metal covering the surface of the diamond powder is generally nickel or cobalt. The surface of diamond powder can be coated with conductive metal by electroless nickel plating (or cobalt plating), or by other methods such as stirring and mixing; since these processes are relatively mature, they will not be described in detail here.

[0050] In electrochemical deposition, the current density during electroplating is typically 1 A / dm³. 2 ~3A / dm 2 The temperature is 50℃~60℃, which ensures a suitable thickness of the deposited functional layer and a high bonding force with the substrate. Furthermore, the diamond content can be adjusted by controlling the concentration of diamond powder in the electroplating solution, which will not be elaborated upon here. Additionally, the electroplating time can be adjusted adaptively to obtain functional layers of different thicknesses; this adjustment method is relatively mature and will not be elaborated upon here.

[0051] Furthermore, the functional layer formed by electrochemical deposition, with a thickness controlled within the range of 5μm to 15μm, exhibits superior performance.

[0052] The steps for depositing a functional layer on the surface of a matrix mesh using PVD are as follows: Using magnetron sputtering technology, diamond and metal are sequentially sputtered onto the surface of a substrate layer to form alternating diamond and metal layers, with all diamond and metal layers forming a functional layer.

[0053] The principle of magnetron sputtering technology is as follows: Under the influence of an electric field E, electrons collide with argon atoms as they fly towards the substrate (in this application, the substrate mesh), causing ionization and generating argon ions and new electrons. The new electrons fly towards the substrate, while the argon ions, under the influence of the electric field, accelerate towards the cathode target and bombard the target surface with high energy, causing sputtering of the target material. In the sputtered particles, neutral target atoms or molecules are deposited on the substrate to form a thin film, while the generated secondary electrons are affected by the electric and magnetic fields, resulting in a drift in the direction indicated by E (electric field) × B (magnetic field), referred to as E×B drift, whose trajectory approximates a cycloid. If it is a toroidal magnetic field, the electrons move in a circular motion on the target surface in an approximate cycloid form. Their movement path is not only very long, but they are also confined to a plasma region close to the target surface, where a large number of argon ions are ionized to bombard the target material, thus achieving a high deposition rate. As the number of collisions increases, the energy of the secondary electrons is exhausted, gradually moving away from the target surface, and finally deposited on the substrate under the influence of the electric field E. Because the electron has very low energy, the energy transferred to the substrate is very small, resulting in a low temperature rise in the substrate.

[0054] When using magnetron sputtering technology, diamond targets and metal targets are sputtered alternately to ensure that diamond layers and metal layers are alternately set. Since magnetron sputtering technology is relatively mature, the specific sputtering process will not be described in detail here.

[0055] In addition, the functional layer formed by magnetron sputtering technology has a thickness controlled within the range of 2μm to 10μm, resulting in better performance.

[0056] S300, post-processing and netting.

[0057] This step involves subjecting the formed printing screen to low-temperature heat treatment to eliminate the substrate mesh and internal stress, and to enhance the bonding force between the functional layer and the substrate mesh. Afterward, a screen frame is used to tighten the printing screen, making it ready for screen printing. The typical low-temperature treatment temperature is 150℃~250℃, and the treatment time is 1h~2h.

[0058] The technical solution of this application will be specifically described below with reference to the embodiments.

[0059] Example 1 This embodiment provides a printing screen, the preparation method of which is as follows: High-carbon steel wire with a carbon content of 0.6% by mass was selected, drawn into a thread with a diameter of 18μm, and woven into a plain weave fabric of 500 mesh / inch as the base mesh. The base mesh was then cleaned and acid-activated.

[0060] Diamond powder with an equivalent average particle size of 3 μm (pretreated with electroless nickel plating) was added to a Watts-type nickel plating solution and vigorously stirred to ensure uniform suspension. The substrate mesh was then placed in the electroplating bath as the cathode and electroplated for 40 minutes at a current density of 2 A / dm² and a temperature of 55°C. This resulted in an 8 μm thick functional layer forming on the surface of each wire, creating a printing screen. The functional layer of the printing screen contained nickel and diamond, with a diamond content of 25% by mass.

[0061] After electroplating, remove the printing screen, clean it with deionized water, and heat-treat it in a vacuum environment at 200℃ for 1.5 hours. Then stretch the printing screen onto the frame.

[0062] Examples 2 to 5 Compared to Example 1, the main difference is that the thickness of the functional layer is changed, as shown in Table 1.

[0063] Examples 6 to 13 Compared to Example 1, the main difference lies in the equivalent particle size and mass content of the diamond, as shown in Table 1.

[0064] Examples 14-17 Compared to Example 1, the main difference is that the diameter of the thread is different, as shown in Table 1.

[0065] Example 18 This embodiment provides a printing screen, the preparation method of which is as follows: High-carbon steel wire with a carbon content of 0.6% by mass was selected, drawn into a thread with a diameter of 18μm, and woven into a plain weave fabric of 500 mesh / inch as the base mesh. The base mesh was then cleaned and acid-activated.

[0066] The substrate mesh is placed in the cathode tank, and the diamond target and the nickel target are alternately bombarded by magnetron sputtering technology. Diamond layers and nickel layers are alternately deposited on the surface of the substrate mesh, and finally an 8μm thick functional layer is formed on the surface of each wire to form a printing screen. The diamond mass content in the printing screen is 25%.

[0067] Clean the printing screen with deionized water and heat-treat it in a vacuum environment at 200°C for 1.5 hours. Then stretch the printing screen onto the frame.

[0068] Comparative Example 1 This comparative example provides a printing screen, the preparation method of which is as follows: High-carbon steel wire with a carbon content of 0.6% by mass was selected, drawn into a thread with a diameter of 18μm, and woven into a plain weave fabric of 500 mesh / inch as the base mesh. The base mesh was then cleaned and acid-activated.

[0069] Clean the substrate screen with deionized water and heat-treat it in a vacuum environment at 200°C for 1.5 hours. Then stretch the substrate screen onto the screen frame to use as a printing screen.

[0070] Performance testing Abrasion resistance test The screen to be tested is installed on the solar cell screen printing production line, and continuous printing is carried out using the same printing parameters (squeegee pressure, printing speed, and paste type). The machine is stopped at regular intervals (e.g., 20,000 times) to detect the surface morphology of the screen and the changes in the line width of the printed electrodes.

[0071] Judgment criteria: When the printing electrode shows obvious grid breaks, incomplete printing, or line width exceeding the specified tolerance range (±10%), the cumulative number of printing cycles at this point is recorded as the screen's lifespan. Each sample is tested 3 times, and the average value is taken.

[0072] Printing performance test This test uses a novel solar cell conductive paste to verify the printing adaptability and stability of the screen printing plate under different paste systems.

[0073] 1. Selection of test slurry.

[0074] The following two representative slurries were selected for the test: For the front-side silver paste, choose the Solamet® series, PV17x series, or PV3Nx series. This series is the mainstream product in the photovoltaic conductive silver paste industry, suitable for metallization of the front electrode of P-type and N-TOPCon cells, and has good printability and fine line drawing capabilities. For the back-side silver paste or aluminum paste, select standard test pastes according to the industry standard YS / T612-2014 "Pastes for Solar Cells".

[0075] 2. General composition of the slurry.

[0076] The conductive paste for solar cells typically consists of three main systems: a conductive phase, which is silver powder or silver-coated copper powder, providing conductivity, with a silver content typically ranging from 86% to 92%, especially the front-side silver paste; an inorganic binder phase, which is glass powder, such as lead-telluride glass, which melts during sintering, etches the antireflective film, and forms ohmic contacts; and an organic carrier, including resins, solvents, and additives, used to adjust rheological properties and ensure printability.

[0077] 3. Test methods and judgment criteria The testing method is as follows: the screen to be tested is installed on a screen printing machine, and the above-mentioned paste is used for continuous printing. The electrode line width, line height and printing defects are checked at regular intervals.

[0078] The criteria for judgment are as follows: "Excellent" is defined as line width deviation ≤ ±5% and no printing defects; "Good" is defined as line width deviation ±5%~±10% and few defects; and "Medium" is defined as line width deviation ≥ ±10% or obvious broken lines or false printing.

[0079] Tension decay test Test method: A screen tension meter was used to measure the tension of the printing screen in its initial state and after a certain number of printing cycles. When measuring the tension, five points were selected: the center of the printing screen and the four corners. The average value was then taken.

[0080] Judgment criteria: Calculate tension retention rate = (average tension after printing / initial average tension) × 100%. The tension retention rate after 100,000 printings is used as the evaluation index. The higher the retention rate, the better the tension stability.

[0081] Functional layer cohesion test Test method: 3M tape was applied to the surface of the functional layer, and rolled three times with a rubber roller to remove air bubbles. After standing for 1 minute, the tape was quickly peeled off at a 90° angle, and the functional layer was observed to see if it peeled off. The same sample was tested three times at different locations.

[0082] Judgment criteria: If no coating peels off in all three tests, the adhesion is deemed qualified.

[0083] Mesh clogging rate test Test method: Using an optical microscope or scanning electron microscope, images of the screen surface are taken after a certain number of printing cycles, and image analysis software is used to count the number of blocked mesh holes.

[0084] Judgment criteria: Mesh clogging rate = (number of clogged meshes / total number of meshes) × 100%. A clogging rate below 5% is considered acceptable.

[0085] Table 1

[0086] In addition, the functional layer bonding strength test results in the embodiments were all qualified, and the mesh clogging rate was qualified after 100,000 printing cycles.

[0087] As can be seen from the above, in the printing screen of this embodiment, since the surface of the substrate mesh contains a functional layer, and the functional layer includes metals such as nickel and cobalt as well as diamond, the wear resistance and tension stability of the printing screen can be greatly improved, and it also has good compatibility with new pastes. The printing screen of Comparative Example 1 does not have a functional layer on its surface, so its wear resistance is poor, its tension stability is not high, and its compatibility with new pastes is also poor.

[0088] In particular, as can be seen from Examples 2 to 5, when the thickness of the functional layer of this application is in the range of 5μm to 15μm, the printing screen has good wear resistance, high tension stability, and good compatibility with new pastes. This is because when the functional layer is in this range, it can provide sufficient wear resistance allowance to significantly extend the service life of the printing screen, while maintaining the original mesh geometry of the screen to ensure printing accuracy and consistency.

[0089] In particular, as can be seen from Examples 6 to 9, when the mass content of diamond in the functional layer in the embodiments of this application is in the range of 15% to 35%, the diamond content is sufficient and it is not easy to fall off. Therefore, the printing screen has good wear resistance, high tension stability, and good compatibility with new pastes.

[0090] In particular, as can be seen from Examples 10 to 13, when the equivalent particle size of diamond in the functional layer of this application is in the range of 1μm to 5μm, the diamond is not easy to agglomerate, nor is it easy to fall off and clog the mesh. Therefore, the printing screen has good wear resistance, high tension stability, and good compatibility with new pastes.

[0091] In particular, as can be seen from Examples 14 to 17, when the diameter of the steel wire in the embodiments of this application is 15μm to 25μm, the mesh size and dimensions of the formed matrix mesh can well meet the requirements of the printing screen, so the printing screen has good compatibility with the new paste.

[0092] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A printing screen, characterized in that, include: The matrix mesh includes steel wires; The surface of the matrix mesh is provided with a functional layer, the material of which includes metal and diamond, and the metal includes at least one of nickel or cobalt.

2. The printing screen according to claim 1, characterized in that, The thickness of the functional layer is 2μm~15μm.

3. The printing screen according to claim 1 or 2, characterized in that, In the functional layer, the metal and the diamond are evenly distributed.

4. The printing screen according to claim 1 or 2, characterized in that, In the functional layer, the metal forms a metal layer, the diamond forms a diamond layer, and the metal layer and the diamond layer are alternately arranged.

5. The printing screen according to claim 1, characterized in that, Based on the quality of the functional layer, the diamond mass content is 15%~35%; and / or, The equivalent particle size of the diamond is 1μm to 5μm.

6. The printing screen according to claim 1, characterized in that, The diameter of the steel wire is 15μm~25μm.

7. The printing screen according to claim 1 or 6, characterized in that, The steel wire is made of high-carbon steel or stainless steel alloy.

8. The printing screen according to claim 7, characterized in that, In the high-carbon steel, the mass percentage of carbon is 0.5% to 0.8%. The stainless steel alloy includes molybdenum, niobium and nitrogen, and the tensile strength of the stainless steel alloy is not less than 1500 MPa.

9. A method for preparing a printing screen, characterized in that, Includes the following steps: Steel wires are woven into a matrix mesh, and then a functional layer is deposited on the surface of the matrix mesh using electrochemical deposition or physical vapor deposition. The functional layer is made of metal and diamond, and the metal includes at least one of nickel or cobalt.

10. The method for preparing a printing screen according to claim 9, characterized in that, Depositing the functional layer on the surface of the substrate mesh using the electrochemical deposition method includes the following steps: The substrate mesh is placed in an electroplating solution, and the functional layer is electroplated and deposited on the surface of the substrate mesh, using the substrate mesh as the cathode. The electroplating solution includes diamond powder and metal ions, wherein the metal ions include at least one of nickel ions or cobalt ions; and the surface of the diamond powder is covered with a conductive metal.

11. The method for preparing a printing screen according to claim 10, characterized in that, The current density during electroplating is 1 A / dm. 2 ~3A / dm 2 The temperature is 50℃~60℃.

12. The method for preparing a printing screen according to claim 9, characterized in that, Depositing the functional layer on the surface of the substrate mesh using the physical vapor deposition method includes the following steps: Using magnetron sputtering technology, diamond and metal are sequentially sputtered onto the surface of the substrate layer to form alternating diamond and metal layers, and all of the diamond and metal layers form the functional layer.

13. The method for preparing a printing screen according to claim 9, characterized in that, After the functional layer is deposited, it will be heat-treated at 150℃~250℃ for 1h~2h.

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