Nickel screen printing plate for anti-counterfeit printing as well as preparation method and application of nickel screen printing plate

Abstract

The invention belongs to the technical field of precise screen printing plate manufacturing, and provides a nickel screen printing plate for anti-counterfeit printing as well as a preparation method and application of the nickel screen printing plate. The composite design of the Ni-P-B gradient nickel net base body and the Ni-Cr alloy pattern metal film is adopted, the Ni-P-B gradient nickel net base body with the phosphorus and boron elements distributed in a gradient mode is constructed in the thickness direction through pulse electroforming, then the high-precision Ni-Cr alloy pattern metal film is formed through pattern electroplating, firm combination of the Ni-P-B gradient nickel net base body and the Ni-Cr alloy pattern metal film is achieved through a metallurgical bonding transition layer, and the Ni-P-B gradient nickel net base body and the Ni-Cr alloy pattern metal film are obtained. The contradiction between high-strength hardness and high-resolution ink passing amount, interface bonding strength and dimensional stability, and long-life durability and microstructure keeping of a traditional screen printing plate is solved, and the screen printing plate has the wide application value of achieving the structural anti-counterfeiting effect which is difficult to imitate by 10-30 [mu] m level fine line patterns and miniature characters in the anti-counterfeiting printing field of paper money, certificates, bills and the like.

Description

Technical Field

[0001] This invention relates to the field of precision screen printing technology, specifically to a nickel screen printing plate for anti-counterfeiting printing, its preparation method, and its application. Background Technology

[0002] Anti-counterfeiting printing is widely used in banknotes, certificates, tickets, and high-end packaging, achieving structural anti-counterfeiting through high-resolution fine lines, microtext, and grayscale patterns. With improved counterfeiting capabilities, screen printing plates must simultaneously meet requirements of 10–30 μm linewidth, ±1 μm tolerance, and high aperture ratio, while possessing high strength, hardness, and abrasion resistance to withstand high-cycle printing, solvent rinsing, and cleaning, maintaining stable edge morphology over the long term. Therefore, developing novel anti-counterfeiting nickel screen printing plates that balance high strength and high resolution, high bonding strength and high dimensional stability, long lifespan, and morphology retention is of great significance. Existing anti-counterfeiting nickel meshes are mostly electroformed from a single alloy, making it difficult to meet comprehensive performance indicators: First, there is a contradiction between strength and hardness and high porosity / high resolution (thickening and hardening easily reduces porosity, while fine mesh walls with high porosity weaken lifespan); second, the pattern layer and substrate are mostly mechanically inlaid or simply composited, and mismatches in composition / stress / thermal expansion easily lead to peeling, stress concentration, and dimensional drift, making it difficult to balance bonding strength and micron-level stability; third, after embossing and cleaning, they are prone to wear and passivation, and microcrack propagation leads to printing degradation. Even as described in CN103373045B, Ni... Fe electroformed stencils are still a single system and have not systematically resolved the above contradictions with gradient and multi-layer composite structures. Summary of the Invention

[0003] The purpose of this invention is to provide a nickel screen printing plate for anti-counterfeiting printing, its preparation method and application, and to solve the contradiction between the structural performance coupling between high strength and hardness and high resolution and high ink throughput, the contradiction between interfacial bonding strength and micron-level dimensional stability, and the contradiction between long life durability and microstructure retention in traditional screen printing plates.

[0004] This invention employs a multi-layer composite synergistic design of a Ni-PB gradient nickel mesh substrate and a Ni-Cr alloy patterned metal film: a gradient distribution of phosphorus and boron along the thickness direction is constructed in the Ni-PB nickel mesh substrate, with low phosphorus and boron in the core to maintain toughness and processability, and high phosphorus and boron in the surface layer to improve hardness and wear resistance; combined with the high-precision patterning and chemical stability of the Ni-Cr alloy patterned metal film, and through a metallurgical bonding transition layer to achieve a gradual matching of composition, stress and thermal expansion, thereby significantly improving mechanical properties, interface reliability and printing durability without sacrificing porosity and ink throughput, achieving multi-performance synergistic optimization that is difficult to achieve with a single alloy system.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A nickel screen printing plate for anti-counterfeiting printing includes a Ni–P–B gradient nickel screen substrate and a metal pattern film disposed on one side of the Ni–P–B gradient nickel screen substrate. The Ni–P–B gradient nickel mesh substrate includes a surface region and a core region sequentially from the outer surface inward along the thickness direction; the thickness of the surface region is 2–8 μm, the mass fraction of phosphorus in the surface region is 6–10 wt%, the mass fraction of boron is 0.05–0.20 wt%, and the balance is nickel and unavoidable impurities; The core region contains 1–5 wt% phosphorus and 0.01–0.049 wt% boron, with the balance being nickel and unavoidable impurities. The metal pattern film is a Ni-Cr alloy pattern metal film, wherein the mass fraction of chromium in the Ni-Cr alloy pattern metal film is 1-5 wt%, and the balance is nickel and unavoidable impurities. A metallurgical bonding transition layer is sandwiched between the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate. The metallurgical bonding transition layer is metallurgically bonded to both the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate.

[0006] The Ni–P–B gradient nickel mesh substrate of the anti-counterfeiting printing nickel mesh screen has a Vickers hardness of not less than 350HV0.2 as measured under standard screen printing conditions.

[0007] Furthermore, the metallurgical bonding transition layer is a Ni–P alloy transition layer; the thickness of the metallurgical bonding transition layer is 1–5 μm, and the mass fraction of phosphorus in the metallurgical bonding transition layer is 4–8 wt%, with the balance being nickel and unavoidable impurities.

[0008] The phosphorus content in the metallurgical bonding transition layer is controlled at 4-8 wt%, falling precisely between the 6-10 wt% of the surface region of the Ni-PB gradient nickel mesh substrate and the low-phosphorus or phosphorus-free composition of the Ni-Cr alloy patterned metal film. This creates a gradual transition in phosphorus content, achieving a smooth connection of the compositional gradient at the interface. This significantly reduces lattice mismatches and differences in thermal expansion coefficients caused by abrupt compositional changes, preventing the initiation and propagation of interfacial microcracks under temperature cycling or mechanical stress. Simultaneously, the 1-5 μm thickness of the metallurgical bonding transition layer ensures sufficient interfacial bonding strength to withstand solvent erosion and mechanical impact, without increasing the overall thickness or decreasing the porosity due to an excessively thick transition layer.

[0009] Furthermore, the total thickness of the Ni–P–B gradient nickel mesh substrate is 60–80 μm; The Ni–P–B gradient nickel mesh substrate has a mesh opening ratio of 30–45%, and the mesh of the Ni–P–B gradient nickel mesh substrate is quadrilateral or rhomboid, with a mesh wall width of 15–30 μm.

[0010] Furthermore, the Ni-PB gradient nickel mesh substrate is obtained by electroforming a Ni-PB electroplating solution containing nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane on a patterned cathode mold. The Ni–P–B gradient nickel mesh substrate is prepared through the following steps: A1. Preparation of Ni–P–B electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 240–320 g / L, nickel chloride hexahydrate 40–60 g / L, boric acid 30–45 g / L, phosphorous acid 10–15 g / L, and dimethylamine borane 0.5–1.0 g / L. Adjust the pH of the solution to 3.5–4.0 to obtain the Ni–P–B electroplating solution. A2. Preparing the patterned cathode mold: First, a resist layer is formed on the surface of a conductive substrate. Then, a selected area of ​​the resist layer is removed by laser direct writing to form a resist pattern layer corresponding to the mesh pattern, so that the exposed area corresponds to the future mesh position and the covered area corresponds to the future mesh wall position, thus obtaining the patterned cathode mold; wherein, the laser direct writing is ultraviolet nanosecond laser direct writing, the laser wavelength is 355 nm, the average power is 1–5 W, the pulse frequency is 20–100 kHz, the scanning speed is 50–500 mm / s, the focused spot diameter is 10–30 μm, and the number of repeated scans is 1–5 times; A3. Electroforming: The patterned cathode mold is immersed in the Ni-P-B electroplating solution for pulse electroforming. The total electroforming time is 60–100 min. During the first 40–60 min of electroforming, the phosphorous acid concentration is maintained at 10–20 g / L and the dimethylamine borane concentration is maintained at 0.5–1.5 g / L by controlling the replenishment amount to form a core region with low phosphorus and boron content. During the last 20–40 min of electroforming, the replenishment amount of phosphorous acid and dimethylamine borane is gradually increased to raise the phosphorous acid concentration to 20–40 g / L and the dimethylamine borane concentration to 1.5–3.0 g / L, so that the mass fraction of phosphorus in the surface region with a thickness of 2–8 μm near the outer surface of the Ni-P-B gradient nickel mesh substrate is 6–10 wt% and the mass fraction of boron is 0.05–0.20 wt%. A4. Termination and Demolding: When the total thickness of the coating reaches 60–80 μm, stop electroforming, remove the patterned cathode mold from the electroplating solution, wash with water and peel off the coating to obtain the Ni–P–B gradient nickel mesh substrate.

[0011] Furthermore, in the electroforming process of step A3, the temperature of the Ni–P–B electroplating solution is 52–56℃, the cathode current density is 2.5–3.5A / dm², the pulse duty cycle is 30–60%, and the pulse frequency is 100–300Hz. By adding phosphorous acid and dimethylamine borane in stages, a gradient distribution of phosphorus and boron content is formed in the thickness direction of the Ni–P–B gradient nickel mesh substrate.

[0012] Furthermore, the thickness of the Ni–Cr alloy patterned metal film is 2–6 μm; The minimum linewidth of the Ni–Cr alloy patterned metal film is 10–30 μm, and the linewidth tolerance is no greater than ±1 μm.

[0013] Furthermore, the Ni-Cr alloy patterned metal film is obtained by electroforming on a patterned substrate using a Ni-Cr electroplating solution containing nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and chromium chloride hexahydrate. The Ni-Cr alloy patterned metal film is prepared through the following steps: B1. Preparation of Ni-Cr electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and chromium chloride hexahydrate in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 200–280 g / L, nickel chloride hexahydrate 30–50 g / L, boric acid 30–45 g / L and chromium chloride hexahydrate 5–20 g / L. Under stirring conditions, monitor the pH value in real time with a pH meter. Adjust the pH value of the solution to 3.0–4.0 by adding 10 wt% sulfuric acid aqueous solution and / or 10 wt% sodium hydroxide aqueous solution dropwise to obtain the Ni-Cr electroplating solution. B2. Fabrication of a patterned substrate: A hollow pattern is formed on the surface of a conductive metal substrate by laser etching, so that the substrate surface has hollow areas and non-hollow areas corresponding to the target anti-counterfeiting pattern. The minimum line width of the hollow pattern is 10–30 μm, thus obtaining a patterned substrate. The laser etching is ultraviolet nanosecond laser etching with a laser wavelength of 355 nm, an average power of 3–10 W, a pulse frequency of 20–200 kHz, a scanning speed of 20–300 mm / s, a focused spot diameter of 10–30 μm, and 5–30 repeated scans, so that the etched area forms a hollow area that penetrates the thickness of the substrate. B3. Electroplating to form a Ni-Cr alloy patterned metal film: The patterned substrate is immersed in the Ni-Cr electroplating solution as a cathode and subjected to DC electroplating for 10–60 min to form a Ni-Cr alloy patterned metal film with a thickness of 2–6 μm in the non-cutout area, wherein the mass fraction of chromium in the Ni-Cr alloy patterned metal film is 1–5 wt%. B4. Demolding: Peel the Ni-Cr alloy patterned metal film from the patterned substrate to obtain the Ni-Cr alloy patterned metal film.

[0014] Furthermore, in step B3, the temperature of the Ni–Cr electroplating solution is 45–60°C, and the cathode current density is 1.0–3.0 A / dm².

[0015] This invention employs a Ni-PB gradient nickel mesh matrix to enhance the strength, hardness, wear resistance, and structural stability of the screen printing plate. By electroforming and controlling the concentrations of phosphorous acid and dimethylamine borane in stages, a gradient of phosphorus and boron content is created: the core maintains a low phosphorus and boron content to preserve toughness, plasticity, and resistance to crack propagation, reducing the risk of screen wall fracture; the outer surface 2–8 μm layer increases the co-deposition amount, forming a high-hardness Ni-PB ternary alloy phase, achieving a Vickers hardness ≥350HV0.2, and improving wear and scratch resistance, maintaining the microscopic accuracy of the screen wall morphology and pattern edges over the long term. The gradient structure also alleviates warping caused by uneven composition and internal stress, achieving gradual stress release and uniform distribution through a progressive transition. This allows the screen to maintain dimensional stability and deformation resistance even under conditions of 30–45% open area and 15–30 μm fine mesh wall, meeting the requirements for high-precision printing at the 10–30 μm level. Pulse electroforming further refines grains and improves density and uniformity. By controlling the duty cycle and frequency, it suppresses concentration polarization and grain coarsening, thereby improving overall performance and lifespan stability at the microstructure level.

[0016] The introduction of Ni-Cr alloy graphic metal film further enhances the chemical stability and oxidation resistance of the screen printing plate. The appropriate addition of chromium element at 1-5wt% can form a dense chromium oxide passivation layer on the film surface, effectively blocking the corrosion of the substrate by ink solvents and cleaning agents. At the same time, the excellent machinability and low internal stress characteristics of Ni-Cr alloy enable it to achieve a minimum graphic line width of 10-30μm and a line width tolerance of ±1μm through high-precision graphic technology such as laser etching. This meets the ultra-high precision requirements of anti-counterfeiting printing for microtext and fine line graphics, and ultimately achieves synergistic optimization of the multi-layer composite structure in terms of interface reliability, graphic accuracy and long-term stability.

[0017] This invention also discloses a method for preparing a nickel screen printing plate for anti-counterfeiting printing, comprising the following steps: S1. Composite Connection: The Ni-Cr alloy patterned metal film is bonded to the ink-emitting side surface of the Ni-P-B gradient nickel mesh substrate, so that the patterned area of ​​the Ni-Cr alloy patterned metal film corresponds to the area to be imaged on the screen, forming a bond; under the condition of 45-60℃, the bond is immersed in Ni-P electroplating solution, so that the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate are electrically connected as the same cathode, and at least one side of the bonded area is kept in communication with the electrolyte in the circumferential direction. Electroplating is performed at a cathode current density of 1.0-2.0 A / dm² for 10-30 min, forming a metallurgical bonding transition layer between the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate, realizing the metallurgical bonding between the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate; the Ni-P electroplating solution contains nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and phosphorous acid; S2. Cleaning and drying: Take out the composite nickel screen printing plate, rinse it with deionized water in sequence, and dry it to obtain the nickel screen printing plate for anti-counterfeiting printing.

[0018] The Ni-P electroplating solution is prepared by dissolving nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and phosphorous acid sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 220–280 g / L, nickel chloride hexahydrate 35–55 g / L, boric acid 30–45 g / L, and phosphorous acid 10–30 g / L. The pH of the solution is then adjusted to 3.0–4.0 to obtain the Ni-P electroplating solution.

[0019] This invention also discloses the application of a nickel screen printing plate for anti-counterfeiting printing, specifically used to print fine line graphics, microtext, or grayscale patterns with a line width of 10–30 μm on banknotes, certificates, tickets, brand labels, or high-end packaging substrates, so as to achieve a structural anti-counterfeiting effect that is difficult to imitate.

[0020] This invention employs a step-by-step preparation and metallurgical bonding process to enhance the interfacial bonding strength, dimensional stability, and pattern accuracy retention of nickel mesh screens used in anti-counterfeiting printing. By first independently preparing the Ni-PB gradient nickel mesh substrate and the Ni-Cr alloy pattern metal film, and then precisely aligning and bonding them, a metallurgical bonding transition layer is formed using Ni-P electroplating to achieve composite bonding. This process design effectively avoids the risk of interfacial stress concentration and debonding caused by differences in the composition of multiple layers during a single electroforming process.

[0021] Ni P B-gradient nickel mesh matrix and Ni Cr alloy graphic metal films play complementary and synergistic roles in the screen printing: the substrate provides the structural framework and ensures strength, hardness, wear resistance, and lifespan—the core is tough enough to bear stress, while the surface layer is highly hard and wear-resistant, maintaining strength and durability even under conditions of high porosity and fine mesh walls; Ni The Cr pattern film is responsible for high-precision pattern definition and surface protection—Cr passivation enhances corrosion / oxidation resistance, supporting 10–30 μm linewidths and ±1 μm tolerances. In terms of wear resistance, the hardened substrate surface provides basic load-bearing capacity, and although the 2–6 μm pattern film is thin, its dense Cr oxide passivation layer further enhances scratch resistance and chemical corrosion resistance. Regarding precision and dimensional stability, the substrate gradient and pulsed electroforming stress control provide a stable substrate, and the pattern film is precisely replicated via laser etching. The key lies in the metallurgical bonding transition layer, which achieves gradual changes in composition and stress, reducing interface abrupt changes and stress concentration. This prevents peeling, cracking, and dimensional drift under temperature cycling, imprinting, and solvent erosion, thus achieving a comprehensive improvement in high strength, high precision, long lifespan, and high stability.

[0022] Beneficial technical effects: 1. Synergistic optimization of structure and performance, overcoming traditional contradictions: Through the multi-layer composite design of Ni-PB gradient matrix and Ni-Cr patterned film, combined with gradient component distribution and metallurgical bonding transition layer, the coupling contradiction between high strength and hardness and high resolution / high ink throughput is overcome; while achieving a Vickers hardness ≥350HV0.2, a porosity of 30–45%, a fine mesh wall of 15–30μm and a minimum linewidth of 10–30μm are achieved, significantly improving the overall performance and adaptability.

[0023] 2. Significantly enhanced interface reliability and excellent dimensional stability: A metallurgical bonding transition layer is used to connect the substrate and the patterned film. The phosphorus mass fraction of the transition layer is 4–8 wt%, which achieves a smooth connection of phosphorus content and composition gradient, alleviates lattice mismatch and thermal expansion differences, and avoids stress concentration and debonding. It still maintains ±1 μm linewidth tolerance and micron-level dimensional stability under high temperature curing, temperature cycling and long-term stress.

[0024] 3. Significantly improved printing durability and long lifespan with high precision: The high phosphorus and boron hardened area on the substrate surface is superimposed with a Ni-Cr pattern film chromium oxide passivation layer, which significantly enhances wear resistance, scratch resistance and chemical corrosion resistance. This ensures that the screen retains the microscopic precision of the screen wall and edges without degradation or passivation after tens of thousands to hundreds of thousands of printing, washing and cleaning cycles, extending its lifespan and reducing the frequency of replacement.

[0025] 4. The gradient structure design is ingenious and the process is highly controllable: Through pulse electroforming and staged regulation of the chemical system, the distribution of phosphorus and boron gradients is precisely controlled, taking into account both the toughness of the core and the wear resistance of the surface. The gradient transition is natural, the internal stress is uniform, the parameters are controllable, which is conducive to large-scale production, and combined with laser etching, high-precision and repeatable preparation of Ni-Cr patterned films can be achieved.

[0026] 5. Outstanding anti-counterfeiting application value and broad market prospects: This nickel screen printing plate can print 10-30μm fine lines, microtext and grayscale patterns on substrates such as banknotes, certificates, tickets, brand labels and high-end packaging, forming a highly difficult-to-counterfeit structural anti-counterfeiting effect, improving security and reliability, and has important practical value and broad application prospects. Attached Figure Description

[0027] Figure 1 The image shows the EDS energy spectrum of the core region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0028] Figure 2 The image shows the EDS energy spectrum of the surface region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0029] Figure 3 The image shows the EDS energy spectrum of the metallurgical bonding transition layer in Example 1.

[0030] Figure 4 The image shows the EDS spectrum of the Ni-Cr alloy patterned metal film from Example 1.

[0031] Figure 5 The image shows the XRD diffraction pattern of the core region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0032] Figure 6 The image shows the XRD diffraction pattern of the surface region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0033] Figure 7 This is a high-resolution XPS Ni 2p spectrum of the surface region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0034] Figure 8 This is a high-resolution XPS p2p spectrum of the surface region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0035] Figure 9 This is a high-resolution XPS B1s spectrum of the surface region of the Ni-PB gradient nickel mesh substrate in Example 1.

[0036] Figure 10 The image shows the XPS high-resolution Cr 2p spectrum of the Ni-Cr alloy patterned metal film in Example 1. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0038] Example 1 This embodiment provides a nickel screen printing plate for anti-counterfeiting printing, including a Ni-PB gradient nickel screen substrate and a metal pattern film disposed on one side of the Ni-PB gradient nickel screen substrate in this embodiment.

[0039] The Ni-PB gradient nickel mesh substrate of this embodiment includes a surface region and a core region sequentially from the outer surface inward along the thickness direction. The Vickers hardness of the Ni-PB gradient nickel mesh substrate for anti-counterfeiting printing in this embodiment, measured under standard screen printing conditions, is 380 HV0.2.

[0040] The total thickness of the Ni-PB gradient nickel mesh substrate in this embodiment is 70 μm. In the surface region, which is 5 μm thick and located near the outer surface of the Ni-PB gradient nickel mesh substrate, the phosphorus content is 8 wt% and the boron content is 0.12 wt%, with the balance being nickel and unavoidable impurities. The mesh opening ratio of the Ni-PB gradient nickel mesh substrate in this embodiment is 37%, and the mesh wall width is 22 μm. In the core region of the Ni-PB gradient nickel mesh substrate in this embodiment, the phosphorus content is 3 wt% and the boron content is 0.045 wt%. The mesh of the Ni-PB gradient nickel mesh substrate in this embodiment is rhomboid. Unless otherwise stated, in this embodiment, "mass fraction of elements in the surface region / core region" refers to the average mass fraction of the corresponding region from the outer surface inward along the thickness direction.

[0041] The Ni-Cr alloy patterned metal film of this embodiment has a thickness of 4 μm, wherein the mass fraction of chromium is 3 wt%, and the balance is nickel and unavoidable impurities. The minimum pattern linewidth of the Ni-Cr alloy patterned metal film of this embodiment is 20 μm, and the linewidth tolerance is ±0.8 μm.

[0042] In this embodiment, a metallurgical bonding transition layer is sandwiched between the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate. The metallurgical bonding transition layer is metallurgically bonded to both the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate.

[0043] In this embodiment, the thickness of the metallurgical bonding transition layer is 3 μm, and the mass fraction of phosphorus in the metallurgical bonding transition layer is 6 wt%, with the balance being nickel and unavoidable impurities.

[0044] The anti-counterfeiting printing nickel screen printing plate of this embodiment is prepared through the following steps: Step S1: Prepare the Ni-PB gradient nickel mesh substrate, specifically including the following steps: Step A1: Prepare the Ni-PB electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 280 g / L, nickel chloride hexahydrate 50 g / L, boric acid 37 g / L, phosphorous acid 15 g / L, and dimethylamine borane 1.0 g / L. Adjust the pH of the solution to 3.75 to obtain the Ni-PB electroplating solution.

[0045] Step A2: Prepare the patterned cathode mold. Take a stainless steel conductive substrate and degrease and clean it. Then, attach an acid-resistant dry film anti-corrosion material to the surface of the conductive substrate to form an anti-corrosion layer with a thickness of 20 μm. Next, use an ultraviolet nanosecond laser (wavelength 355 nm, average power 3 W, pulse frequency 50 kHz, scanning speed 200 mm / s, focused spot diameter approximately 20 μm, repeated scanning twice) to laser-write and remove the anti-corrosion layer to form an anti-corrosion patterned layer corresponding to the diamond-shaped mesh pattern. The exposed area corresponds to the future mesh position, and the covered area corresponds to the future mesh wall position, thus obtaining the patterned cathode mold. Before electroforming, degrease the patterned cathode mold with an alkaline degreasing solution and rinse it with deionized water until there is no visible oil film on the surface and no obvious foam residue in the rinsing solution.

[0046] Step A3: Electroforming. The patterned cathode mold of this embodiment is immersed in the Ni-PB electroplating solution of this embodiment. Pulse electroforming is performed at a cathode current density of 3.0 A / dm² at a temperature of 54°C, a pulse duty cycle of 45%, a pulse frequency of 200 Hz, and a total electroforming time of 80 min. During the first 50 min of electroforming, the phosphorous acid concentration is maintained at 15 g / L and the dimethylamine borane concentration is maintained at 1.0 g / L by controlling the amount of phosphorous acid added, so as to form a core region with low phosphorus and boron content. During the last 30 min of electroforming, the amount of phosphorous acid and dimethylamine borane added is gradually increased, so that the phosphorous acid concentration is increased to 30 g / L and the dimethylamine borane concentration is increased to 2.25 g / L, so as to form a surface alloy region with 8 wt% phosphorus and 0.12 wt% boron in a 5 μm thick surface region near the outer surface of the Ni-PB gradient nickel mesh substrate of this embodiment.

[0047] Step A4: Termination and Demolding. Electroforming is stopped when the total coating thickness reaches 70 μm. The patterned cathode mold of this embodiment is removed from the electroplating solution, rinsed with deionized water, and the coating is peeled off to obtain a Ni-PB gradient nickel mesh substrate with an open area ratio of 37% and a mesh wall width of 22 μm.

[0048] Step A5: Quality control. It is detected that the mass fraction of phosphorus element in the 5-μm surface layer region of the Ni-P-B gradient nickel mesh substrate in this embodiment is 8 wt%, the mass fraction of boron element is 0.12 wt%, and the Vickers hardness of the Ni-P-B gradient nickel mesh substrate in this embodiment is 380 HV0.2, all of which meet the requirements, and it is determined that the preparation is qualified.

[0049] Step S2: Prepare the Ni-Cr alloy patterned metal film, which specifically includes the following steps: Step B1: Prepare the Ni-Cr electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and chromium chloride hexahydrate in deionized water. The concentrations of each component in the obtained solution are: nickel sulfate hexahydrate 240 g / L, nickel chloride hexahydrate 40 g / L, boric acid 37 g / L, and chromium chloride hexahydrate 12 g / L, and adjust the pH value of the solution to 3.5 to obtain the Ni-Cr electroplating solution.

[0050] Step B2: Prepare the patterned substrate. Take a copper conductive metal substrate, first degrease and clean it; then use ultraviolet nanosecond laser (wavelength 355 nm, average power 6 W, pulse frequency 100 kHz, scanning speed 100 mm / s, focal spot diameter about 20 μm, repeated scanning 15 times) to perform laser etching on the copper conductive metal substrate according to the target anti-counterfeiting graphic path until the etched area penetrates the substrate thickness to form a hollow pattern, so that the substrate surface has a hollow area and a non-hollow area corresponding to the target anti-counterfeiting graphic, and obtain the patterned substrate; the minimum line width of the hollow pattern is 20 μm. Before electroplating, use an alkaline degreasing solution to degrease the patterned substrate and rinse it with deionized water until there is no visible oil film on the surface and no obvious foam residue in the rinsing solution.

[0051] Step B3: Electroplate to form the Ni-Cr alloy patterned metal film. Immerse the patterned substrate in this embodiment as the cathode into the Ni-Cr electroplating solution in this embodiment, and under the condition of a temperature of 52 °C, electroform with a cathode current density of 2.0 A / dm² for 35 min to form a Ni-Cr alloy patterned metal film with a thickness of 4 μm in the non-hollow area. The mass fraction of chromium element in the Ni-Cr alloy patterned metal film in this embodiment is 3 wt%.

[0052] Step B4: Demold. Peel the Ni-Cr alloy patterned metal film in this embodiment from the patterned substrate in this embodiment to obtain a Ni-Cr alloy patterned metal film with an original graphic line width of 20 μm and a line width tolerance of ±0.8 μm.

[0053] Step S3: Composite bonding. The Ni-Cr alloy patterned metal film of this embodiment is bonded to the ink outlet side surface of the Ni-PB gradient nickel mesh substrate of this embodiment, so that the pattern area of ​​the Ni-Cr alloy patterned metal film of this embodiment corresponds to the area of ​​the screen to be imaged, forming a bonded body.

[0054] Preparation of Ni-P electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and phosphorous acid in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 250 g / L, nickel chloride hexahydrate 45 g / L, boric acid 35 g / L, and phosphorous acid 20 g / L. Adjust the pH of the solution to 3.5.

[0055] At a temperature of 52°C, the bonding body of this embodiment is immersed in a Ni-P electroplating solution, so that the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate are electrically connected as the same cathode, and at least one side of the bonding area is kept in communication with the electrolyte in the circumferential direction. Electroplating is performed for 20 min at a cathode current density of 1.5 A / dm². A metallurgical bonding transition layer with a thickness of 3 μm is formed between the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate of this embodiment. The mass fraction of phosphorus in the metallurgical bonding transition layer of this embodiment is 6 wt%, and the balance is nickel and unavoidable impurities, thereby achieving metallurgical bonding between the two.

[0056] Step S4: Cleaning and Drying. Remove the laminated nickel screen printing plate, rinse it thoroughly with deionized water, and dry it at 60°C for 30 minutes to obtain the finished nickel screen printing plate for anti-counterfeiting printing.

[0057] The nickel screen printing plate for anti-counterfeiting printing in this embodiment is used to print fine line graphics, microtext, or grayscale patterns with a line width of 20 μm on banknotes, certificates, tickets, brand labels, or high-end packaging substrates to achieve a structural anti-counterfeiting effect that is difficult to imitate.

[0058] Example 2 This embodiment provides a nickel screen printing plate for anti-counterfeiting printing, including a Ni-PB gradient nickel screen substrate and a metal pattern film disposed on one side of the Ni-PB gradient nickel screen substrate in this embodiment.

[0059] The Ni-PB gradient nickel mesh substrate of this embodiment includes a surface region and a core region sequentially from the outer surface inward along the thickness direction. The Vickers hardness of the Ni-PB gradient nickel mesh substrate for anti-counterfeiting printing in this embodiment, measured under standard screen printing conditions, is 410 HV0.2.

[0060] The total thickness of the Ni-PB gradient nickel mesh substrate in this embodiment is 76 μm. In the surface region, which is 7 μm thick and located near the outer surface of the Ni-PB gradient nickel mesh substrate, the phosphorus content is 9.5 wt% and the boron content is 0.18 wt%, with the balance being nickel and unavoidable impurities. The mesh opening ratio of the Ni-PB gradient nickel mesh substrate in this embodiment is 33%, and the mesh wall width is 27 μm. In the core region of the Ni-PB gradient nickel mesh substrate in this embodiment, the phosphorus content is 1.5 wt% and the boron content is 0.02 wt%. The mesh of the Ni-PB gradient nickel mesh substrate in this embodiment is quadrilateral. Unless otherwise stated, in this embodiment, "mass fraction of elements in the surface region / core region" refers to the average mass fraction of the corresponding region from the outer surface inward along the thickness direction.

[0061] The Ni-Cr alloy patterned metal film of this embodiment has a thickness of 5 μm, wherein the mass fraction of chromium is 4.5 wt%, and the balance is nickel and unavoidable impurities. The minimum pattern linewidth of the Ni-Cr alloy patterned metal film of this embodiment is 15 μm, and the linewidth tolerance is ±0.7 μm.

[0062] In this embodiment, a metallurgical bonding transition layer is sandwiched between the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate. The metallurgical bonding transition layer is metallurgically bonded to both the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate.

[0063] In this embodiment, the thickness of the metallurgical bonding transition layer is 4 μm, and the mass fraction of phosphorus in the metallurgical bonding transition layer is 7.5 wt%, with the balance being nickel and unavoidable impurities.

[0064] The anti-counterfeiting printing nickel screen printing plate of this embodiment is prepared through the following steps: Step S1: Prepare the Ni-PB gradient nickel mesh substrate, specifically including the following steps: Step A1: Prepare the Ni-PB electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 310 g / L, nickel chloride hexahydrate 58 g / L, boric acid 43 g / L, phosphorous acid 11 g / L, and dimethylamine borane 0.6 g / L. Adjust the pH of the solution to 3.9 to obtain the Ni-PB electroplating solution.

[0065] Step A2: Prepare the graphic cathode mold. Take a titanium alloy conductive substrate, first degrease and clean it; then attach an acid-resistant dry film resist material to the surface of the conductive substrate to form a resist layer with a thickness of 20 μm; then use an ultraviolet nanosecond laser (wavelength 355 nm, average power 3 W, pulse frequency 50 kHz, scanning speed 150 mm / s, focused spot diameter about 25 μm, repeated scanning 2 times) to perform laser direct writing removal on the resist layer to form a resist pattern layer corresponding to the quadrilateral mesh pattern, so that the exposed area corresponds to the future mesh position and the covered area corresponds to the future mesh wall position, and obtain the graphic cathode mold. Before electroforming, degrease the graphic cathode mold with an alkaline degreasing solution and rinse it with deionized water until there is no visible oil film on the surface and there is no obvious foam residue in the rinsing solution.

[0066] Step A3: Electroforming. Immerse the graphic cathode mold of this embodiment in the Ni-P-B electroplating solution of this embodiment, and perform pulse electroforming at a cathode current density of 3.4 A / dm² under the condition of a temperature of 55.5 °C, with a pulse duty cycle of 55% and a pulse frequency of 280 Hz, and the total electroforming time is 95 min. Among them, within the first 58 min of electroforming, by controlling the replenishment amount, the concentration of phosphorous acid is maintained at 11 g / L and the concentration of dimethylamine borane is maintained at 0.6 g / L to form a core region with lower phosphorus and boron contents. Within the last 37 min of electroforming, gradually increase the replenishment amounts of phosphorous acid and dimethylamine borane to increase the concentration of phosphorous acid to 38 g / L and the concentration of dimethylamine borane to 2.9 g / L, so as to form a surface alloy region with 9.5 wt% phosphorus and 0.18 wt% boron in the surface layer region with a thickness of 7 μm near the outer surface of the Ni-P-B gradient nickel mesh of this embodiment.

[0067] Step A4: Termination and demolding. Stop electroforming when the total thickness of the coating reaches 76 μm, take out the graphic cathode mold of this embodiment from the electroplating solution, rinse it with deionized water, and then peel off the coating to obtain a Ni-P-B gradient nickel mesh substrate with a pore opening rate of 33% and a mesh wall width of 27 μm.

[0068] Step A5: Quality control. Detect that the mass fraction of phosphorus element in the 7-μm surface layer region of the Ni-P-B gradient nickel mesh substrate of this embodiment is 9.5 wt% and the mass fraction of boron element is 0.18 wt%, and the Vickers hardness of the Ni-P-B gradient nickel mesh substrate of this embodiment is 410 HV0.2, both of which meet the requirements, and it is determined that the preparation is qualified.

[0069] Step S2: Prepare the Ni-Cr alloy graphic metal film, which specifically includes the following steps: Step B1: Prepare the Ni-Cr electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and chromium chloride hexahydrate in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 270 g / L, nickel chloride hexahydrate 48 g / L, boric acid 43 g / L, and chromium chloride hexahydrate 18 g / L. Adjust the pH of the solution to 3.8 to obtain the Ni-Cr electroplating solution.

[0070] Step B2: Preparation of the patterned substrate. A stainless steel conductive metal substrate is first degreased and cleaned. Then, an ultraviolet nanosecond laser (wavelength 355 nm, average power 8 W, pulse frequency 150 kHz, scanning speed 80 mm / s, focused spot diameter approximately 15 μm, repeated scanning 20 times) is used to laser-etch the stainless steel conductive metal substrate along the target anti-counterfeiting pattern path until the etched area penetrates the substrate thickness to form a hollow pattern. This results in a hollow area and a non-hollow area on the substrate surface corresponding to the target anti-counterfeiting pattern, thus obtaining the patterned substrate. The minimum linewidth of the hollow pattern is 15 μm. Before electroplating, the patterned substrate is degreased with an alkaline degreasing solution and rinsed with deionized water until there is no visible oil film on the surface and no obvious foam residue in the rinsing solution.

[0071] Step B3: Electroplating to form a Ni-Cr alloy patterned metal film. The patterned substrate of this embodiment is immersed in the Ni-Cr electroplating solution of this embodiment, using it as the cathode. At a temperature of 58°C, DC electroplating is performed for 55 min at a cathode current density of 2.8 A / dm² to form a Ni-Cr alloy patterned metal film with a thickness of 5 μm in the non-perforated area. The mass fraction of chromium in the Ni-Cr alloy patterned metal film of this embodiment is 4.5 wt%.

[0072] Step B4: Demolding. The Ni-Cr alloy patterned metal film of this embodiment is peeled off from the patterned substrate of this embodiment to obtain a Ni-Cr alloy patterned metal film that retains the original pattern linewidth of 15 μm and the linewidth tolerance of ±0.7 μm.

[0073] Step S3: Composite bonding. The Ni-Cr alloy patterned metal film of this embodiment is bonded to the ink outlet side surface of the Ni-PB gradient nickel mesh substrate of this embodiment, so that the pattern area of ​​the Ni-Cr alloy patterned metal film of this embodiment corresponds to the area of ​​the screen to be imaged, forming a bonded body.

[0074] Preparation of Ni-P electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and phosphorous acid in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 270 g / L, nickel chloride hexahydrate 48 g / L, boric acid 40 g / L and phosphorous acid 25 g / L. Adjust the pH of the solution to 3.8.

[0075] At a temperature of 58°C, the bonding body of this embodiment is immersed in a Ni-P electroplating solution, so that the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate are electrically connected as the same cathode, and at least one side of the bonding area is kept in communication with the electrolyte in the circumferential direction. Electroplating is performed for 28 min at a cathode current density of 1.9 A / dm², and a metallurgical bonding transition layer with a thickness of 4 μm is formed between the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate of this embodiment. The mass fraction of phosphorus in the metallurgical bonding transition layer of this embodiment is 7.5 wt%, thereby achieving metallurgical bonding between the two.

[0076] Step S4: Cleaning and Drying. Remove the laminated nickel screen printing plate, rinse it thoroughly with deionized water, and dry it at 65°C for 25 minutes to obtain the finished nickel screen printing plate for anti-counterfeiting printing.

[0077] The nickel screen printing plate for anti-counterfeiting printing in this embodiment is used to print fine line graphics, microtext, or grayscale patterns with a line width of 15 μm on banknotes, certificates, tickets, brand labels, or high-end packaging substrates to achieve a structural anti-counterfeiting effect that is difficult to imitate.

[0078] Example 3 This embodiment provides a nickel screen printing plate for anti-counterfeiting printing, including a Ni-PB gradient nickel screen substrate and a metal pattern film disposed on one side of the Ni-PB gradient nickel screen substrate in this embodiment.

[0079] The Ni-PB gradient nickel mesh substrate of this embodiment includes a surface region and a core region sequentially from the outer surface inward along the thickness direction. The Vickers hardness of the Ni-PB gradient nickel mesh substrate for anti-counterfeiting printing in this embodiment, measured under standard screen printing conditions, is 390 HV0.2.

[0080] The total thickness of the Ni-PB gradient nickel mesh substrate in this embodiment is 78 μm. In the surface region, which is 7.5 μm thick and located near the outer surface of the Ni-PB gradient nickel mesh substrate, the phosphorus content is 6.2 wt% and the boron content is 0.19 wt%, with the balance being nickel and unavoidable impurities. The mesh opening ratio of the Ni-PB gradient nickel mesh substrate in this embodiment is 31%, and the mesh wall width is 29 μm. In the core region of the Ni-PB gradient nickel mesh substrate in this embodiment, the phosphorus content is 1.2 wt% and the boron content is 0.048 wt%. The mesh of the Ni-PB gradient nickel mesh substrate in this embodiment is rhomboid. Unless otherwise stated, in this embodiment, "mass fraction of elements in the surface region / core region" refers to the average mass fraction of the corresponding region from the outer surface inward along the thickness direction.

[0081] The Ni-Cr alloy patterned metal film of this embodiment has a thickness of 5.5 μm, with a chromium content of 4.8 wt% and the balance being nickel and unavoidable impurities. The minimum pattern linewidth of the Ni-Cr alloy patterned metal film of this embodiment is 11 μm, and the linewidth tolerance is ±0.6 μm.

[0082] In this embodiment, a metallurgical bonding transition layer is sandwiched between the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate. The metallurgical bonding transition layer is metallurgically bonded to both the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate.

[0083] The metallurgical bonding transition layer in this embodiment has a thickness of 4.5 μm and a phosphorus content of 7.8 wt%, with the balance being nickel and unavoidable impurities.

[0084] The anti-counterfeiting printing nickel screen printing plate of this embodiment is prepared through the following steps: Step S1: Prepare the Ni-PB gradient nickel mesh substrate, specifically including the following steps: Step A1: Prepare the Ni-PB electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 315 g / L, nickel chloride hexahydrate 59 g / L, boric acid 31 g / L, phosphorous acid 10.5 g / L, and dimethylamine borane 0.55 g / L. Adjust the pH of the solution to 3.95 to obtain the Ni-PB electroplating solution.

[0085] Step A2: Prepare the patterned cathode mold. Take a nickel conductive substrate and degrease and clean it. Then, attach an acid-resistant dry film anti-corrosion material to the surface of the conductive substrate to form an anti-corrosion layer with a thickness of 20 μm. Next, use an ultraviolet nanosecond laser (wavelength 355 nm, average power 3 W, pulse frequency 50 kHz, scanning speed 120 mm / s, focused spot diameter approximately 25 μm, repeated scanning twice) to laser-write and remove the anti-corrosion layer to form an anti-corrosion patterned layer corresponding to the diamond mesh pattern, so that the exposed area corresponds to the future mesh position and the covered area corresponds to the future mesh wall position, thus obtaining the patterned cathode mold. Before electroforming, degrease the patterned cathode mold with an alkaline degreasing solution and rinse it with deionized water until there is no visible oil film on the surface and no obvious foam residue in the rinsing solution.

[0086] Step A3: Electroforming. The patterned cathode mold of this embodiment is immersed in the Ni-PB electroplating solution of this embodiment. Pulse electroforming is performed at a temperature of 55.8°C and a cathode current density of 2.55 A / dm², with a pulse duty cycle of 58%, a pulse frequency of 110 Hz, and a total electroforming time of 98 min. During the first 60 min of electroforming, the phosphorous acid concentration is maintained at 10.5 g / L and the dimethylamine borane concentration is maintained at 0.55 g / L by controlling the amount of phosphorous acid added, in order to form a core region with low phosphorus and boron content. During the last 38 min of electroforming, the amount of phosphorous acid and dimethylamine borane added is significantly increased, raising the phosphorous acid concentration to 38 g / L and the dimethylamine borane concentration to 2.85 g / L, in order to form a surface alloy region with 6.2 wt% phosphorus and 0.19 wt% boron in a 7.5 μm thick surface region near the outer surface of the Ni-PB gradient nickel mesh substrate of this embodiment.

[0087] Step A4: Termination and Demolding. Electroforming is stopped when the total coating thickness reaches 78 μm. The patterned cathode mold of this embodiment is removed from the electroplating solution, rinsed with deionized water, and the coating is peeled off to obtain a Ni-PB gradient nickel mesh substrate with an open area ratio of 31% and a mesh wall width of 29 μm.

[0088] Step A5: Quality Control. The surface 7.5 μm region of the Ni-PB gradient nickel mesh substrate in this embodiment was tested, and the phosphorus mass fraction was 6.2 wt%, the boron mass fraction was 0.19 wt%, and the Vickers hardness of the Ni-PB gradient nickel mesh substrate in this embodiment was 390 HV0.2. All these conditions were met, and the preparation was deemed qualified.

[0089] Step S2: Prepare a Ni-Cr alloy patterned metal film, specifically including the following steps: Step B1: Prepare the Ni-Cr electroplating solution. Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and chromium chloride hexahydrate in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 275 g / L, nickel chloride hexahydrate 49 g / L, boric acid 31 g / L, and chromium chloride hexahydrate 19 g / L. Adjust the pH of the solution to 3.05 to obtain the Ni-Cr electroplating solution.

[0090] Step B2: Preparation of the patterned substrate. A titanium alloy conductive metal substrate is taken and first degreased and cleaned. Then, an ultraviolet nanosecond laser (wavelength 355 nm, average power 10 W, pulse frequency 200 kHz, scanning speed 50 mm / s, focused spot diameter approximately 10 μm, repeated scanning 30 times) is used to laser etch the titanium alloy conductive metal substrate along the target anti-counterfeiting pattern path until the etched area penetrates the substrate thickness to form a hollow pattern. This results in a hollow area and a non-hollow area on the substrate surface corresponding to the target anti-counterfeiting pattern, thus obtaining the patterned substrate. The minimum linewidth of the hollow pattern is 11 μm. Before electroplating, the patterned substrate is degreased with an alkaline degreasing solution and rinsed with deionized water until there is no visible oil film on the surface and no obvious foam residue in the rinsing solution.

[0091] Step B3: Electroplating to form a Ni-Cr alloy patterned metal film. The patterned substrate of this embodiment is immersed in the Ni-Cr electroplating solution of this embodiment, using it as the cathode. At a temperature of 59°C, DC electroplating is performed for 58 min at a cathode current density of 2.9 A / dm², forming a Ni-Cr alloy patterned metal film with a thickness of 5.5 μm in the non-perforated area. The mass fraction of chromium in the Ni-Cr alloy patterned metal film of this embodiment is 4.8 wt%.

[0092] Step B4: Demolding. The Ni-Cr alloy patterned metal film of this embodiment is peeled off from the patterned substrate of this embodiment to obtain a Ni-Cr alloy patterned metal film that retains the original pattern linewidth of 11 μm and the linewidth tolerance of ±0.6 μm.

[0093] Step S3: Composite Connection. The Ni-Cr alloy patterned metal film of this embodiment is bonded to the ink-emitting side surface of the Ni-PB gradient nickel mesh substrate of this embodiment, so that the patterned area of ​​the Ni-Cr alloy patterned metal film corresponds to the area to be imaged on the screen, forming a bonded body. Preparation of Ni-P electroplating solution: Nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and phosphorous acid are dissolved in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 275 g / L, nickel chloride hexahydrate 49 g / L, boric acid 38 g / L, and phosphorous acid 28 g / L. The pH of the solution is adjusted to 3.9.

[0094] At a temperature of 59°C, the bonding body of this embodiment is immersed in a Ni-P electroplating solution, so that the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate are electrically connected as the same cathode, and at least one side of the bonding area is kept in communication with the electrolyte in the circumferential direction. Electroplating is performed for 29 min at a cathode current density of 1.95 A / dm², and a metallurgical bonding transition layer with a thickness of 4.5 μm is formed between the Ni-Cr alloy patterned metal film and the Ni-PB gradient nickel mesh substrate of this embodiment. The mass fraction of phosphorus in the metallurgical bonding transition layer of this embodiment is 7.8 wt%, thereby achieving metallurgical bonding between the two.

[0095] Step S4: Cleaning and Drying. Take out the composite nickel screen printing plate, rinse it thoroughly with deionized water, and dry it at 70°C for 20 minutes to obtain the finished nickel screen printing plate for anti-counterfeiting printing.

[0096] The nickel screen printing plate for anti-counterfeiting printing in this embodiment is used to print fine line graphics, microtext, or grayscale patterns with a line width of 11 μm on banknotes, certificates, tickets, brand labels, or high-end packaging substrates to achieve a structural anti-counterfeiting effect that is difficult to imitate.

[0097] Example 1 employs a moderate parameter configuration, with a surface layer of 8 wt% P / B and a core layer of 0.12 wt% P / B, creating a suitable gradient. The matrix hardness is 380 HV0.2, and the mesh wall width of 22 μm and porosity of 37% balance strength and ink permeability. Ni The Cr graphic film, with a thickness of 4 μm, Cr content of 3 wt%, and a line width of 20 μm, achieves a balance between clarity and wear resistance. It offers a wide process window and good reproducibility, making it suitable for stable batch anti-counterfeiting printing of banknotes and passports. Example 2, geared towards high performance, features a significant gradient between a surface layer with 9.5 wt% P and 0.18 wt% B, and a core layer with low P and low B (1.5 wt% / 0.02 wt%), resulting in a hardness of 410 HV0.2. A 27 μm mesh wall and 33% porosity enhance strength and resistance to deformation. The graphic film, with 4.5 wt% Cr, a thickness of 5 μm, and a line width of 15 μm, improves precision and corrosion resistance. A 4 μm transition layer with 7.5 wt% P strengthens the bond, making it suitable for ultra-long lifespan and extremely high anti-counterfeiting levels. Example 3, used for boundary verification, has a total thickness of 78 μm, a surface layer thickness of 7.5 μm, and a mesh wall thickness of 29 μm, approaching the upper limit, while the surface layer has 6.2 wt% P and the core layer has 1.2 wt% P. With parameters such as wt% and an opening ratio of 31% and a minimum linewidth of 11 μm approaching the lower limit, it is proven that a wide parameter range is achievable. A special gradient is formed by a surface layer thickness of 7.5 μm and high B (0.19 wt%) and a core layer of low P and high B (1.2 wt% / 0.048 wt%), resulting in a hardness of 390 HV0.2. High precision and strong bonding are achieved with an ultra-fine linewidth of 11 μm, Cr 4.8 wt%, film thickness of 5.5 μm, and a transition layer of 4.5 μm and P 7.8 wt%, supporting ultra-high anti-counterfeiting and ultra-fine graphic applications as well as subsequent optimization.

[0098] Comparative Example 1 The process is basically the same as in Example 1, except that: in the later stage of electroforming in step A3 (last 30 min), the phosphorous acid replenishment strategy is adjusted to gradually increase the concentration of phosphorous acid in the electroplating solution from 15 g / L and stabilize it at 18 g / L; the dimethylamine borane replenishment strategy is the same as in Example 1, so that the phosphorus mass fraction in the 0–5 μm region on the surface of the obtained Ni–P–B gradient nickel mesh substrate is about 5 wt%; other component ratios, current densities, temperatures, times and subsequent steps are the same as in Example 1.

[0099] Comparative Example 2 The process is basically the same as in Example 1, except that the total electroforming time in step A3 is shortened from 80 min to 55 min, with the initial electroforming time being 25 min and the subsequent electroforming time being 30 min, resulting in a total thickness of only 50 μm for the Ni–P–B gradient nickel mesh substrate. Other aspects, such as the composition of the Ni–P–B electroplating solution, pulse parameters, gradient control of phosphorus and boron content in the surface and core regions, porosity and mesh wall linewidth design, and subsequent Ni–Cr patterned metal film preparation and composite steps, are the same as in Example 1.

[0100] Comparative Example 3 The process is basically the same as in Example 1, except that the mesh pitch of the laser-etched resist pattern is adjusted in step A2. This reduces the mesh opening rate of the Ni–P–B gradient nickel mesh substrate to 25% while keeping the mesh wall width unchanged at 22 μm. The Ni–P–B electroforming process parameters and the subsequent Ni–Cr patterned metal film and metallurgical bonding steps remain unchanged.

[0101] Comparative Example 4 The process is basically the same as in Example 1, except that the mesh pitch is enlarged in step A2. While keeping the mesh wall width at 22 μm, the mesh opening rate of the Ni–P–B gradient nickel mesh substrate is increased to 50%, and the Ni–P–B electroforming process and the Ni–Cr patterned metal film preparation and composite conditions are kept consistent.

[0102] Comparative Example 5 The process is basically the same as in Example 1, except that in step B3 the Ni-Cr electroplating time is shortened from 35 min to 8 min, so that the thickness of the Ni-Cr alloy patterned metal film is only 1 μm. The composition of the Ni-Cr electroplating solution, temperature, cathode current density and pattern linewidth design are the same as in Example 1.

[0103] Comparative Example 6 The process is basically the same as in Example 1, except that in step B1, the concentration of chromium chloride hexahydrate in the Ni-Cr electroplating solution is reduced from 12 g / L to 1 g / L, so that the mass fraction of chromium in the obtained Ni-Cr alloy patterned metal film is only 0.3 wt%, while other electroplating conditions and pattern parameters remain unchanged.

[0104] Comparative Example 7 The process is basically the same as in Example 1, except that in step S3, when preparing the Ni-P electroplating solution, the concentration of phosphorous acid is reduced from 20 g / L in Example 1 to 8 g / L. Electroplating is performed under the same conditions as in Example 1, where the concentration of other components, pH, temperature and cathode current density are the same, so that the mass fraction of phosphorus in the metallurgical bonding transition layer is about 3 wt%.

[0105] Comparative Example 8 The process is basically the same as in Example 1, except that the step-by-step addition of phosphorous acid and dimethylamine borane is omitted in step A3. During the entire 80-minute electroplating process, the concentration of phosphorous acid in the electroplating solution is maintained at 15 g / L (with an allowable fluctuation of ±10%) and the concentration of dimethylamine borane is maintained at 1.0 g / L (with an allowable fluctuation of ±10%). These concentrations are kept basically constant through sampling analysis and replenishment, so that the mass fractions of phosphorus and boron in the Ni–P–B nickel mesh matrix are basically uniform in the thickness direction and no longer exhibit a gradient distribution. Other electroplating solution formulations, temperatures, current densities, and geometric parameters remain unchanged.

[0106] Comparative Example 9 The process is essentially the same as in Example 1, except that dimethylamine borane is not added when preparing the Ni-P-B electroplating solution in step A1. The solution contains only nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, and phosphorous acid. Specifically, the Ni-PB electroplating solution consists of: 280 g / L nickel sulfate hexahydrate, 50 g / L nickel chloride hexahydrate, 37 g / L boric acid, and 15 g / L phosphorous acid, with a pH of 3.75. During the first 50 minutes of electroforming, the phosphorous acid concentration is maintained at 15 g / L by controlling the amount added. During the last 30 minutes of electroforming, the amount of phosphorous acid added is gradually increased to raise the concentration to 30 g / L. The resulting nickel mesh substrate is a Ni-P nickel mesh, not a Ni-P-B gradient nickel mesh substrate, and the total thickness, porosity, and mesh wall width remain the same as in Example 1.

[0107] Performance testing: Experiment 1: The test object was a Ni–P–B gradient nickel mesh substrate (example / comparative example); Test objective: to verify that the surface Vickers hardness is ≥350 HV0.2 and to obtain the hardness-depth gradient; Test principle: HV is converted from the diagonal of the Vickers indentation; Experimental method: a polished section was prepared according to ASTM E3, and points were taken every 1 μm from the outer surface at a distance of 0–8 μm and every 5 μm from the core. The load was 0.2 kgf, held for 10 s, and n=5 per point; Standard basis: ISO 6507-1 / ASTM E384; Key parameters: 23±2°C, indentation spacing ≥3d.

[0108] Experiment 2: The test object was a finished nickel screen printing plate for anti-counterfeiting printing; Test objective: To confirm the total thickness of the substrate (60–80 μm), surface layer (2–8 μm), Ni–Cr film (2–6 μm), transition layer (1–5 μm), and the porosity (30–45%), screen wall width (15–30 μm), minimum line width (10–30 μm) with tolerance ≤ ±1 μm; Test principle: Metallographic / optical measurement and area fraction statistics; Experimental method: After preparing the cross-section according to ASTM E3, the thickness of each layer was measured under a microscope (≥30 points per layer). The plane was analyzed using an optical microscope and image analysis to count ≥500 mesh openings and calculate the porosity; Standard basis: ISO 1463 / ASTM B487; Key parameters: Magnification ≥500×, pixel calibration; Data processing: Mean ± SD with 95% CI provided.

[0109] Experiment 3: The test objects were the Ni–P–B gradient substrate cross-section and the surface of the Ni–Cr alloy patterned metal film; the test objective was to verify that the surface / core P and B content was within the specified range and that the core content was lower than the surface content, and to verify that the Cr content of the Ni–Cr film was 1–5 wt% and the P content of the transition layer was 4–8 wt%; the test principle was SEM. EDS quantitative analysis and distribution acquisition by line scanning; Experimental method: After polishing the cross section, EDS line scanning (step size 1 μm, ≥3 lines) and surface scanning are performed, and standard samples are used for calibration if necessary; Standard basis: ASTM E1508; Key parameters: 15–20 kV, counting time ≥30 s.

[0110] Experiment 4: The test object was the Ni-Cr patterned film / metallurgical bonding transition layer / Ni-P-B gradient matrix composite interface; Test objective: to quantitatively evaluate the interfacial bonding strength and failure mode; Test principle: the pull-out method was used to measure the maximum pull-out stress and determine the failure location; Experimental method: pull-out specimens were prepared according to ISO 4624 (vertical pull-out after the pull studs were bonded and cured), with n≥5 per batch, and the fracture surface was optically / SEM interpreted; Standard basis: ISO 4624 or ASTM D4541; Key parameters: pull-out rate approximately 1 MPa / s; Data processing: the average bonding strength in MPa ± SD.

[0111] Experiment 5: The test object is a finished nickel mesh stencil (including the clamped state); Test objective: To verify the stability of line width / mesh size and interface non-delamination under temperature cycling; Test principle: Temperature cycling induces thermal expansion mismatch and internal stress changes, and the stability is evaluated by the difference in dimensions before and after the change; Experimental method: According to IEC 60068 2 14 proceed 20 Cycle at 80°C for 100 cycles (30 min dwell time), and measure ≥50 line widths and mesh pitches at the same coordinate before and after each cycle; Standard basis: IEC 60068 2 14; Key parameters: calibration microscope; Data processing: output linewidth drift Δw.

[0112] Experiment 6: The test object is the ink outlet surface of the screen wall (exposed Ni-Cr film); Test objective: To evaluate the retention of fine patterns after abrasion and cleaning cycles; Test principle: Wear causes the film layer to thin / edge to become blunt, which manifests as a change in the wear rate; Experimental method: According to ASTM G99 ball... Disc wear (load 2 N, speed 0.1 m / s, total stroke 1000 m), followed by solvent wiping and cleaning 500 times, with wear volume measured before and after; Standard: ASTM G99; Key parameters: Al2O3 spheres; Data processing: Wear rate (mm³ / N•m).

[0113] Experiment 7: Test Object: Nickel screen printing plate; Test Objective: To verify the corrosion / solvent erosion resistance brought about by Cr content and passivation effect; Test Principle: Salt spray / immersion accelerates corrosion, and the failure time and surface defects are used for evaluation; Experimental Method: Record the time until pitting / blistering / warping occurs according to ISO 9227 neutral salt spray (35°C, 5% NaCl), and measure the quality change and appearance after immersion in typical ink solvents for 24 h; Standard Basis: ISO 9227 or ASTM B117; Key Parameter: n≥3; Data Processing: Report the mean failure time (h) ± SD and failure type.

[0114] Experiment 8: The test subject is a sample printed on a standard screen printing machine using a nickel screen printing plate; Test objective: To verify the reproducibility, ink throughput, and long-term consistency of 10–30 μm fine lines / microtext; Test principle: The mesh geometry determines the ink throughput; Experimental method: Standard test patterns (including 10–30 μm line arrays) are printed with fixed squeegee hardness and speed, n=3 for each type of screen printing plate, and the ink deposition per unit area is measured; Standard basis: ISO 13660; Key parameters: 23±2°C, 50±5%RH; Data processing: Ink throughput (mg / cm²).

[0115] Figure 1 Ni in Example 1 P The EDS spectrum of the core region of the B-gradient nickel mesh matrix shows a Ni main peak accompanied by P and B characteristic signals, corresponding to 3 wt% P and 0.045 wt% B in the core region, which is used to prove that the core region is a low-P, low-B Ni matrix. P B alloy and used as a gradient starting point; Figure 2 The EDS spectrum of the surface region shows that the P and B signals are enhanced compared to the core, and Ni is still dominant. This corresponds to 8 wt% P and 0.12 wt% B in the surface region, which proves that the surface region is high in P and high in B and forms a clear difference from the core region. Figure 3 This is the EDS energy spectrum of the metallurgical bonding transition layer. It is predominantly Ni with a clear P signal and no Cr or B dominant characteristics, corresponding to a transition layer P content of 6 wt%. This indicates that the transition layer is dominated by Ni. P is the main characteristic and plays a role in component buffering and metallurgical bonding support; Figure 4 For Ni The EDS spectrum of the Cr alloy patterned metal film shows Ni as the dominant component with characteristic Cr signals, corresponding to a film thickness of 4 μm and Cr content of 3 wt% (minimum linewidth 20 μm, linewidth tolerance ±0.8 μm). This is used to confirm that the patterned film is composed of Ni with the specified composition. Cr alloy; Figure 5The XRD diffraction pattern of the core region shows that the Ni phase is dominant and the peaks are relatively concentrated. This is used to characterize the low P and low B core region, which retains obvious nickel-based crystal features and supports mechanical / dimensional stability. Figure 6 The XRD diffraction pattern of the surface region shows that the peaks are more easily broadened than those in the center and are accompanied by background elevation, reflecting that the high P surface may have fine-grained or amorphous characteristics, which is consistent with the requirement of high hardness and wear resistance. Figure 7 The high-resolution XPS Ni 2p spectrum on the surface layer is used to confirm that the surface layer is dominated by Ni and to provide information on its surface chemical state. Figure 8 This is a high-resolution XPS p2p spectrum of the surface layer, used to confirm the presence of phosphorus in the surface Ni. P The presence and chemical environment of system B; Figure 9 The high-resolution B 1s XPS spectrum of the surface layer is used to confirm the detectability of boron in the surface layer and support its alloying effect. Figure 10 For Ni XPS high-resolution Cr 2p spectra on the patterned film were used to confirm the presence of Cr in the patterned film and to demonstrate its stable surface chemical characteristics, thereby jointly supporting the gradient matrix, transition layer buffer, and Ni. The rationality and feasibility of Cr patterned film composite structure.

[0116] As can be seen from the performance of the embodiments and comparative examples in Table 1, the embodiments as a whole have synergistic advantages in hardness, wear resistance, corrosion resistance, interface reliability and linewidth retention: the Ni-P-B gradient structure balances surface hardness and core toughness, thereby improving lifespan and reducing Δw; the Ni-Cr film and appropriate Cr content improve corrosion resistance, while comparative examples 5 / 6 show significant deterioration due to salt spray and wear; when the P content of the transition layer is insufficient (comparative example 7), the interface strength decreases and lifespan is reduced; a low porosity (comparative example 3) limits ink flow, while a high porosity (comparative example 4) easily leads to deformation and increases Δw; an excessively thin substrate (comparative example 2) results in insufficient rigidity and decreased dimensional stability.

[0117] Table 1 Performance summary of examples and comparative examples Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A nickel screen printing plate for anti-counterfeiting printing, characterized in that, It includes a Ni–P–B gradient nickel mesh substrate and a metal pattern film disposed on one side of the Ni–P–B gradient nickel mesh substrate; The Ni–P–B gradient nickel mesh substrate includes a surface region and a core region sequentially from the outer surface inward along the thickness direction; the thickness of the surface region is 2–8 μm, the mass fraction of phosphorus in the surface region is 6–10 wt%, the mass fraction of boron is 0.05–0.20 wt%, and the balance is nickel and unavoidable impurities; The core region contains 1–5 wt% phosphorus and 0.01–0.049 wt% boron, with the balance being nickel and unavoidable impurities. The metal pattern film is a Ni-Cr alloy pattern metal film, wherein the mass fraction of chromium in the Ni-Cr alloy pattern metal film is 1-5 wt%, and the balance is nickel and unavoidable impurities. A metallurgical bonding transition layer is sandwiched between the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate. The metallurgical bonding transition layer is metallurgically bonded to both the Ni-Cr alloy patterned metal film and the surface region of the Ni-P-B gradient nickel mesh substrate.

2. The nickel screen printing plate for anti-counterfeiting printing according to claim 1, characterized in that, The metallurgical bonding transition layer is a Ni–P alloy transition layer; the thickness of the metallurgical bonding transition layer is 1–5 μm, and the mass fraction of phosphorus in the metallurgical bonding transition layer is 4–8 wt%, with the balance being nickel and unavoidable impurities.

3. The nickel screen printing plate for anti-counterfeiting printing according to claim 1, characterized in that, The total thickness of the Ni–P–B gradient nickel mesh substrate is 60–80 μm; The Ni–P–B gradient nickel mesh substrate has a mesh opening ratio of 30–45%, and the mesh of the Ni–P–B gradient nickel mesh substrate is quadrilateral or rhomboid, with a mesh wall width of 15–30 μm.

4. The nickel screen printing plate for anti-counterfeiting printing according to claim 1, characterized in that, The Ni–P–B gradient nickel mesh matrix is ​​prepared by the following steps: A1. Preparation of Ni–P–B electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid, phosphorous acid, and dimethylamine borane sequentially in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 240–320 g / L, nickel chloride hexahydrate 40–60 g / L, boric acid 30–45 g / L, phosphorous acid 10–15 g / L, and dimethylamine borane 0.5–1.0 g / L. Adjust the pH of the solution to 3.5–4.0 to obtain the Ni–P–B electroplating solution. A2. Prepare the patterned cathode mold: First, form a resist layer on the surface of the conductive substrate, and then remove the selected area of ​​the resist layer by laser direct writing to form a resist pattern layer corresponding to the mesh pattern, so that the exposed area corresponds to the future mesh position and the covered area corresponds to the future mesh wall position, thus obtaining the patterned cathode mold; A3. Electroforming: The patterned cathode mold is immersed in the Ni-P-B electroplating solution for pulse electroforming. The total electroforming time is 60–100 min. During the first 40–60 min of electroforming, the phosphorous acid concentration is maintained at 10–20 g / L and the dimethylamine borane concentration is maintained at 0.5–1.5 g / L by controlling the replenishment amount to form a core region with low phosphorus and boron content. During the last 20–40 min of electroforming, the replenishment amount of phosphorous acid and dimethylamine borane is gradually increased to raise the phosphorous acid concentration to 20–40 g / L and the dimethylamine borane concentration to 1.5–3.0 g / L, so that the mass fraction of phosphorus in the surface region with a thickness of 2–8 μm near the outer surface of the Ni-P-B gradient nickel mesh substrate is 6–10 wt% and the mass fraction of boron is 0.05–0.20 wt%. A4. Termination and Demolding: When the total thickness of the coating reaches 60–80 μm, stop electroforming, remove the patterned cathode mold from the electroplating solution, wash with water and peel off the coating to obtain the Ni–P–B gradient nickel mesh substrate.

5. The nickel screen printing plate for anti-counterfeiting printing according to claim 4, characterized in that, In the electroforming process of step A3, the temperature of the Ni–P–B electroplating solution is 52–56℃, the cathode current density is 2.5–3.5A / dm², the pulse duty cycle is 30–60%, and the pulse frequency is 100–300Hz. By adding phosphorous acid and dimethylamine borane in stages, a gradient distribution of phosphorus and boron content is formed in the thickness direction of the Ni–P–B gradient nickel mesh substrate.

6. The nickel screen printing plate for anti-counterfeiting printing according to claim 1, characterized in that, The thickness of the Ni–Cr alloy patterned metal film is 2–6 μm; The minimum linewidth of the Ni–Cr alloy patterned metal film is 10–30 μm, and the linewidth tolerance is no greater than ±1 μm.

7. The nickel screen printing plate for anti-counterfeiting printing according to claim 6, characterized in that, The Ni–Cr alloy patterned metal film is prepared by the following steps: B1. Preparation of Ni-Cr electroplating solution: Dissolve nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and chromium chloride hexahydrate in deionized water. The concentrations of each component in the resulting solution are: nickel sulfate hexahydrate 200–280 g / L, nickel chloride hexahydrate 30–50 g / L, boric acid 30–45 g / L and chromium chloride hexahydrate 5–20 g / L. Adjust the pH of the solution to 3.0–4.0 to obtain the Ni-Cr electroplating solution. B2. Preparation of graphic substrate: A hollow pattern is formed on the surface of a conductive metal substrate by laser etching, so that the substrate surface has hollow areas and non-hollow areas corresponding to the target anti-counterfeiting graphic. The minimum line width of the hollow pattern is 10–30 μm, thus obtaining the graphic substrate. B3. Electroplating to form a Ni-Cr alloy patterned metal film: The patterned substrate is immersed in the Ni-Cr electroplating solution as a cathode and subjected to DC electroplating for 10–60 min to form a Ni-Cr alloy patterned metal film with a thickness of 2–6 μm in the non-cutout area, wherein the mass fraction of chromium in the Ni-Cr alloy patterned metal film is 1–5 wt%. B4. Demolding: Peel the Ni-Cr alloy patterned metal film from the patterned substrate to obtain the Ni-Cr alloy patterned metal film.

8. The nickel screen printing plate for anti-counterfeiting printing according to claim 7, characterized in that, In step B3, the temperature of the Ni–Cr electroplating solution is 45–60℃, and the cathode current density is 1.0–3.0 A / dm².

9. The method for preparing a nickel screen printing plate for anti-counterfeiting printing according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Composite Connection: The Ni-Cr alloy patterned metal film is bonded to the ink-emitting side surface of the Ni-P-B gradient nickel mesh substrate, so that the patterned area of ​​the Ni-Cr alloy patterned metal film corresponds to the area to be imaged on the screen, forming a bond; under the condition of 45-60℃, the bond is immersed in Ni-P electroplating solution, so that the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate are electrically connected as the same cathode, and at least one side of the bonded area is kept in communication with the electrolyte in the circumferential direction. Electroplating is performed at a cathode current density of 1.0-2.0 A / dm² for 10-30 min, forming a metallurgical bonding transition layer between the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate, realizing the metallurgical bonding between the Ni-Cr alloy patterned metal film and the Ni-P-B gradient nickel mesh substrate; the Ni-P electroplating solution contains nickel sulfate hexahydrate, nickel chloride hexahydrate, boric acid and phosphorous acid; S2. Cleaning and drying: Take out the composite nickel screen printing plate, rinse it with deionized water in sequence, and dry it to obtain the nickel screen printing plate for anti-counterfeiting printing.

10. The application of the nickel screen printing stencil for anti-counterfeiting printing according to any one of claims 1-8 or the nickel screen printing stencil for anti-counterfeiting printing prepared by the preparation method according to claim 9 in anti-counterfeiting printing, characterized in that, Used for printing fine-line graphics, microtext, or grayscale patterns with a line width of 10–30 μm on banknotes, certificates, tickets, brand labels, or high-end packaging substrates.

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