Flexible wiring board with composite electromagnetic shielding film and method for manufacturing the same

Abstract

The application discloses a flexible circuit board with a composite electromagnetic shielding film and a manufacturing method thereof. The method comprises the following steps: providing an elastic matrix solution and a metal conductive solution respectively; forming an electromagnetic shielding film solution based on the elastic matrix solution and the metal conductive solution; providing a flexible board substrate; coating the electromagnetic shielding film solution on the flexible board substrate; and making the electromagnetic shielding film solution form a composite electromagnetic shielding film to obtain a target flexible circuit board. The composite electromagnetic shielding film is not prone to delamination and fracture in the dynamic bending application of the FPC product, can simultaneously meet the requirements of the increasingly high bendability and service life of the FPC product, has a simple process, a self-defined coating shape, and can realize fixed-point and fixed-quantity coating; the thickness, area and surface roughness of the formed film can be controlled; the cost waste can be reduced; and the design of the lightweight and thin flexible circuit board is facilitated.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing, specifically to a flexible circuit board with a composite electromagnetic shielding film and its manufacturing method. Background Technology

[0002] Flexible printed circuits (FPCs) are increasingly widely used in electronic devices due to their lightweight, thinness, and excellent flexibility, bendability, high-density connectivity, vibration resistance, and shock resistance. With the rapid development of the electronics industry, especially the rise of foldable screen phones, portable and wearable devices, the foldable screen FPC market is experiencing rapid growth, and the reliability requirements for FPCs are becoming increasingly stringent.

[0003] Electromagnetic shielding film (EMI shielding film) is a functional film used in FPC to block external electromagnetic interference (EMI), suppress internal signal leakage, and improve signal integrity. It is the core material for FPC to work stably in high-frequency, flexible, and harsh environments. It is usually composed of conductive materials (such as silver, copper, carbon, etc.) and polymer substrates (such as polyimide PI, polyethylene terephthalate PET, etc.).

[0004] Traditional electromagnetic shielding films typically employ a three-layer structure: an insulating layer, a conductive layer, and an adhesive layer. This structure is prone to delamination and breakage during dynamic bending applications of FPC products, leading to a shorter product lifespan. Therefore, as FPCs evolve towards higher frequency band compatibility (e.g., THz band), extreme environment adaptability (e.g., space electronic environments), and intelligent features (e.g., adaptive tuning shielding), existing electromagnetic shielding films cannot simultaneously meet the increasingly stringent requirements for flexibility and lifespan in FPC products. Summary of the Invention

[0005] In view of this, the present invention provides a flexible circuit board with a composite electromagnetic shielding film and a method for manufacturing the same, in order to solve the problem that existing electromagnetic shielding films are prone to delamination and breakage in dynamic bending applications of FPC products, which makes it impossible to meet the increasingly high requirements for bendability and lifespan.

[0006] This invention provides a method for manufacturing a flexible circuit board with a composite electromagnetic shielding film, the method comprising:

[0007] Elastic matrix solution and metallic conductive solution are provided respectively;

[0008] An electromagnetic shielding film solution is formed based on the elastic matrix solution and the metallic conductive solution.

[0009] A flexible circuit board substrate is provided, and the electromagnetic shielding film solution is coated on the flexible circuit board substrate to form a composite electromagnetic shielding film, thereby obtaining the target flexible circuit board.

[0010] Optionally, the elastic matrix solution includes:

[0011] Provide elastic matrix materials;

[0012] The elastic matrix material is dissolved in a first organic solvent to completely dissolve the elastic matrix material, forming the elastic matrix solution.

[0013] Optionally, the elastic matrix material includes any one or more of polystyrene-isoprene-polystyrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-ethylene-butene-styrene block copolymers, polyurethanes, thermoplastic polyurethanes, and acrylates.

[0014] Optionally, the metal conductive solution includes:

[0015] Provide metallic conductive materials;

[0016] The conductive metal material is dissolved in a second organic solvent to completely dissolve the conductive metal material, forming the conductive metal solution.

[0017] Optionally, the metallic conductive material includes any one or more of silver, copper, nickel, and aluminum.

[0018] Optionally, an electromagnetic shielding film solution is formed based on the elastic matrix solution and the metallic conductive solution, comprising:

[0019] The elastic matrix solution is added to the conductive metal solution, and the conductive metal solution and the elastic matrix solution are mixed evenly using a gradient stirring method to obtain the electromagnetic shielding film solution.

[0020] Optionally, the gradient stirring method includes a low-speed stirring process with a first process parameter, a high-speed shearing process with a second process parameter, and a vacuum degassing process with a third process parameter, wherein the low-speed stirring process, the high-speed shearing process, and the vacuum degassing process are executed sequentially.

[0021] The first process parameter includes stirring speed and stirring time, the second process parameter includes shearing speed and shearing time, and the third process parameter includes vacuum pressure and degassing time.

[0022] Optionally, the flexible substrate has a pre-set dynamic bending zone;

[0023] The electromagnetic shielding film solution is coated onto the flexible circuit board substrate to form a composite electromagnetic shielding film, thereby obtaining the target flexible circuit board, comprising:

[0024] According to the preset coating parameters, the electromagnetic shielding film solution is uniformly coated on the dynamic bending area of ​​the flexible board substrate;

[0025] According to preset curing parameters, the flexible circuit board substrate coated with the electromagnetic shielding film solution is cured to form the composite electromagnetic shielding film on the flexible circuit board substrate, thereby obtaining the target flexible circuit board.

[0026] Optionally, the preset coating parameters include wet film thickness, and the preset curing parameters include curing temperature and curing time.

[0027] In addition, the present invention also provides a flexible circuit board with a composite electromagnetic shielding film, which is manufactured using the aforementioned manufacturing method.

[0028] The beneficial effects of this invention are as follows: By mixing an elastic matrix solution with a conductive metal solution, a hybrid electromagnetic shielding film solution with electromagnetic shielding function is formed. This solution is then coated onto a flexible circuit board substrate to form a functional thin film for suppressing electromagnetic interference, namely a composite electromagnetic shielding film. This hybrid structure film has excellent electromagnetic shielding performance and can significantly improve the bendability of the resulting flexible circuit board. This effectively overcomes the impact of electromagnetic shielding film breakage on the product lifespan during dynamic bending applications of flexible circuit boards with composite electromagnetic shielding films. Compared to traditional three-layer electromagnetic shielding films... The composite electromagnetic shielding film provided by this invention is less prone to delamination and breakage in the dynamic bending application of FPC products. It can simultaneously meet the increasingly high requirements of flexibility and lifespan of FPC products, providing important research value for the future development of dynamic bending of flexible circuit boards. At the same time, in the manufacturing process of flexible circuit boards with composite electromagnetic shielding film, there is no need for punching or tearing off the transfer film, the process is simple, the coating shape can be customized, and fixed-point and quantitative coating can be achieved. The coating thickness, area and surface roughness of the formed film can be controlled, which can reduce cost waste and is conducive to the lightweight and thin design of flexible circuit boards. Attached Figure Description

[0029] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0030] Figure 1 A flowchart of a method for manufacturing a flexible circuit board with a composite electromagnetic shielding film according to Embodiment 1 of the present invention is shown.

[0031] Figure 2 A cross-sectional view of the target flexible circuit board formed in Embodiment 1 of the present invention is shown.

[0032] The labels in the attached figures are explained as follows:

[0033] 1. Flexible board substrate; 2. Composite electromagnetic shielding film; 21. Elastic matrix material; 22. Metallic conductive material. Detailed Implementation

[0034] 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. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0035] This embodiment provides a method for manufacturing a flexible circuit board with a composite electromagnetic shielding film, such as... Figure 1 As shown, it includes:

[0036] S1: Provides an elastic matrix solution and a metal conductive solution respectively;

[0037] S2: An electromagnetic shielding film solution is formed based on the elastic matrix solution and the metallic conductive solution;

[0038] S3: Provide a flexible circuit board substrate, and coat the electromagnetic shielding film solution onto the flexible circuit board substrate so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, thereby obtaining the target flexible circuit board.

[0039] In this embodiment, a hybrid electromagnetic shielding film solution with electromagnetic shielding function is formed by mixing an elastic matrix solution with a conductive metal solution. This solution is then coated onto a flexible circuit board substrate to form a functional thin film for suppressing electromagnetic interference, namely a composite electromagnetic shielding film. This hybrid structure film has excellent electromagnetic shielding performance and can significantly improve the bendability of the resulting flexible circuit board. This effectively overcomes the impact of electromagnetic shielding film breakage on product life during dynamic bending applications of flexible circuit boards with composite electromagnetic shielding films. Compared with traditional three-layer electromagnetic shielding films, the composite electromagnetic shielding film provided by this invention is less prone to delamination and breakage during dynamic bending applications of FPC products. It can simultaneously meet the increasingly high requirements of bendability and lifespan of FPC products, providing important research value for the future development of dynamic bending of flexible circuit boards. At the same time, in the manufacturing process of flexible circuit boards with composite electromagnetic shielding films, there is no need for punching or tearing off the transfer film. The process is simple, the coating shape can be customized, and fixed-point and quantitative coating can be achieved. The coating thickness, area, and surface roughness of the formed film can all be controlled, which can reduce cost waste and is conducive to the lightweight and thin design of flexible circuit boards.

[0040] The following provides a detailed description of each step of the manufacturing method in this embodiment.

[0041] Preferably, in this embodiment S1, the elastic matrix solution includes:

[0042] S11: Provides an elastic matrix material;

[0043] S12: Dissolve the elastic matrix material in a first organic solvent to completely dissolve the elastic matrix material and form the elastic matrix solution.

[0044] Elastic matrix materials are highly elastic and mostly soluble in organic solvents. The complete dissolution of the elastic matrix material in the first organic solvent facilitates subsequent mixing with the conductive metal solution, which in turn facilitates film formation through coating processes, forming a highly flexible electromagnetic shielding film suitable for roll-to-roll mass production. Furthermore, the elastic matrix solution formed after complete dissolution exhibits strong adhesion to various substrates in FPC products (such as PET, PI, and silicone), facilitating direct coating to form a strong film and effectively improving product quality.

[0045] Preferably, in S11, the elastic matrix material includes any one or more of polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, polyurethane, thermoplastic polyurethane, and acrylate.

[0046] Polystyrene-isoprene-polystyrene block copolymer (SIS) features polystyrene (PS) hard segments and polyisoprene (PI) soft segments separated into spherical, columnar, or layered phases, giving the material excellent flexibility and tear resistance. Its tensile strength can reach 17.25~20.7 MPa, and its elongation at break exceeds 1000%. It maintains flexibility even at a low temperature of -40℃, making it suitable for FPC products that require repeated stretching.

[0047] Styrene-butadiene-styrene block copolymer (SBS) has excellent elasticity and deformation resistance, stable molecular structure, and maintains elasticity in a temperature range of -30℃ to +50℃. It is also suitable for the high flexibility requirements of FPC products.

[0048] Styrene-ethylene-butene-styrene block copolymer (SEBS) has stable properties in a temperature range of -60℃ to +120℃ and also has excellent elasticity and deformation resistance, making it suitable for the high flexibility requirements of FPC products.

[0049] Polyurethane (PU) has an adjustable hardness from Shore A20 (soft rubber roller) to Shore D70 (hard steel rolling roller), with a wide range of adjustable elastic properties; thermoplastic polyurethane (TPU) also has excellent tensile strength and tear strength, and can adapt to different processing environments; acrylic ester can withstand permanent deformation after continuous operation at 150℃ for 1000 hours with a permanent deformation of about 30%.

[0050] The aforementioned elastic matrix materials all possess high elasticity, allowing the film to be bent, folded, or even stretched (with strain reaching 100-300%) after film formation, effectively enhancing the film's flexibility and making it extremely suitable for dynamic bending environments such as flexible electronics and wearable devices.

[0051] Specifically, in S12, each type of elastic matrix material can be selected according to the appropriate type of first organic solvent based on the actual situation.

[0052] For elastic matrix materials such as polystyrene-isoprene-polystyrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-ethylene-butene-styrene block copolymers, and acrylates, their forms are mostly solid particles or block solids. They can be dissolved in primary organic solvents such as toluene, cyclohexane, and ethyl acetate to form a homogeneous, transparent, viscoelastic elastic matrix solution.

[0053] For elastic matrix materials such as polyurethane and thermoplastic polyurethane, their forms are mostly viscous paste or block solid form, which can be dissolved in primary organic solvents such as DMF, THF, acetone, and methyl ethyl ketone to form elastic matrix solutions.

[0054] Preferably, in this embodiment S1, the metal conductive solution provided includes:

[0055] S13: Provides metallic conductive materials;

[0056] S14: Dissolve the conductive metal material in a second organic solvent to completely dissolve the conductive metal material and form the conductive metal solution.

[0057] By completely dissolving the conductive metal material in the solvent, the resulting conductive metal solution can better form a continuous conductive path in the elastic matrix solution. It provides efficient shielding by reflecting and absorbing electromagnetic waves. Therefore, by combining it with the elastic matrix solution, it is convenient to form a film using a coating process. On the other hand, it ensures that the formed film not only achieves electromagnetic shielding function, but also effectively improves stretchability, thereby improving the dynamic bending life of the electromagnetic shielding film in flexible circuit board applications.

[0058] Preferably, in S13, the metallic conductive material includes any one or more of silver, copper, nickel, and aluminum.

[0059] Silver is the metal with the best conductivity, with a surface resistivity of less than 0.010 Ω / cm. Its shielding effectiveness can reach more than 75dB in the 10GHz high-frequency range, making it suitable for scenarios with extremely high shielding requirements. Copper's conductivity is second only to silver, with a shielding effectiveness of 75dB at frequencies above 1GHz. Copper's conductivity allows it to effectively reflect high-frequency electromagnetic waves and reduce signal leakage. Although nickel's conductivity is lower than silver and copper, its high permeability, large magnetic vector attenuation, and strong ability to absorb electromagnetic interference make it effective at 60-65dB in the 5-1800MHz range, especially performing well in the low-frequency range (below 30MHz). Aluminum's conductivity is better than nickel but lower than copper and silver. It can effectively block the penetration of high-frequency electromagnetic waves. Its lightweight characteristics (density is only 1 / 3 of copper) make it advantageous in scenarios where weight reduction is required, maintaining a low cost and weight. This embodiment utilizes the aforementioned conductive metal material to ensure the stretchability of the electromagnetic shielding film in FPC products through a subsequent combination of a highly flexible elastic matrix solution and a highly electromagnetically shielding conductive metal solution. This simultaneously addresses the increasingly stringent requirements for bendability and lifespan of FPC products.

[0060] It should be noted that the steps of preparing the elastic matrix solution described in S11~S12 and the steps of preparing the metal conductive solution described in S13~S14 can be performed simultaneously or sequentially, and the order of execution is not limited.

[0061] Specifically, in S14, the second organic solvent for dissolving the conductive metal material can be selected according to the actual situation, such as ethanol, ethylene glycol, and toluene.

[0062] Preferably, embodiment S2 includes:

[0063] The elastic matrix solution is added to the conductive metal solution, and the conductive metal solution and the elastic matrix solution are mixed evenly using a gradient stirring method to obtain the electromagnetic shielding film solution.

[0064] During the mixing process of the conductive metal solution and the elastic matrix solution, a gradient stirring method involving three processes (i.e., low-speed stirring process, high-speed shearing process, and vacuum degassing process) is adopted. This method can eliminate defects at the interface between the two solutions, achieve effective dispersion between the two solutions, avoid the brittleness caused by rigid filler (material in the conductive metal solution), and ensure that the conductive metal solution and the elastic matrix solution can be fully mixed. This enhances the bonding force between the conductive metal material and the elastic matrix material in the solution, thereby ensuring that the formed electromagnetic shielding film solution has both excellent electromagnetic shielding and flexibility.

[0065] Specifically, the gradient stirring method includes a low-speed stirring process with a first process parameter, a high-speed shearing process with a second process parameter, and a vacuum degassing process with a third process parameter, and the low-speed stirring process, the high-speed shearing process, and the vacuum degassing process are executed sequentially.

[0066] Low-speed stirring enables the initial dispersion of the two material solutions: the conductive metal solution and the elastic matrix solution. High-speed shearing breaks up the agglomeration of conductive materials in the conductive metal solution, allowing the conductive metal solution to be uniformly and stably dispersed into the elastic matrix solution. Vacuum degassing allows the gas in the mixed solution to escape due to physical expansion, thereby obtaining a defect-free and uniform electromagnetic shielding film solution.

[0067] Specifically, the first process parameter includes stirring speed and stirring time, the second process parameter includes shearing speed and shearing time, and the third process parameter includes vacuum pressure and degassing time.

[0068] By controlling the process parameters mentioned above in the three processes, it can be ensured that each process achieves the expected results, thereby effectively guaranteeing the quality of the electromagnetic shielding film solution.

[0069] Preferably, in this embodiment S3, the flexible substrate has a pre-set dynamic bending area;

[0070] In step S3, the electromagnetic shielding film solution is coated onto the flexible circuit board substrate, thereby forming a composite electromagnetic shielding film to obtain the target flexible circuit board, comprising:

[0071] S31: According to the preset coating parameters, the electromagnetic shielding film solution is uniformly coated on the dynamic bending area of ​​the flexible board substrate;

[0072] S32: According to preset curing parameters, the flexible circuit board substrate coated with the electromagnetic shielding film solution is cured to form the composite electromagnetic shielding film on the flexible circuit board substrate, thereby obtaining the target flexible circuit board.

[0073] Coating according to preset coating parameters allows the electromagnetic shielding film solution to be evenly covered on the dynamic bending area of ​​the flexible board substrate. It enables fixed-point and quantitative coating according to customization, and the coating thickness and area are controllable, which helps to reduce costs and waste. Then, curing according to preset curing parameters ensures that the electromagnetic shielding film solution on the dynamic bending area forms a film efficiently, thereby improving the quality of the composite electromagnetic shielding film.

[0074] Specifically, in this embodiment, the flexible board substrate refers to the FPC semi-finished product to be used to make the electromagnetic shielding film. It has already completed conventional processes such as circuit forming, reinforcement, and electroless nickel plating in the FPC manufacturing process. Specific details will not be repeated here.

[0075] Specifically, the preset coating parameters include wet film thickness, and the preset curing parameters include curing temperature and curing time.

[0076] By using the aforementioned preset coating and curing parameters, the required composite electromagnetic shielding film can be efficiently formed on the flexible board substrate, thereby creating an FPC product that can simultaneously meet the requirements of high flexibility and lifespan.

[0077] Specifically, the coating in this embodiment includes, but is not limited to, blade coating and spin coating.

[0078] The cross-sectional structure of the target flexible circuit board formed in this embodiment is as follows: Figure 2 As shown, in Figure 2 In the diagram, 1 represents the flexible substrate, 2 represents the composite electromagnetic shielding film, 21 represents the elastic matrix material in the composite electromagnetic shielding film, and 22 represents the metallic conductive material in the composite electromagnetic shielding film.

[0079] To further demonstrate the specific details of the production process, this embodiment provides the following two specific production examples.

[0080] Specific production example 1:

[0081] (1) Sample preparation: 100g SIS solution, 27g flake silver powder, FPC test plate.

[0082] (2) Disperse the flake silver powder in a solvent (such as water, ethanol, ethylene glycol, toluene, etc.) and add an appropriate amount of surfactant (such as polyvinylpyrrolidone PVP, polyvinyl alcohol PVA, etc.) or dispersant (such as sulfonate dispersant) to stabilize the suspension and prevent agglomeration, forming silver paste, which is a gray-black or dark gray viscous liquid, which is a metal conductive solution.

[0083] (3) The silver paste is gradually added to the SIS solution (i.e., the elastic matrix solution) and mixed evenly according to the gradient stirring method. The low-speed stirring process is carried out for initial dispersion at a stirring speed of 200~400 rpm and a stirring time of 10 min; the high-speed shearing process is carried out at a shearing speed of 800~1200 rpm and a shearing time of 30 min to break the agglomeration of the silver material components; the vacuum degassing process is carried out at a vacuum pressure of -0.09 MPa and a degassing time of 20 min. The solid content in the electromagnetic shielding film solution is 33%.

[0084] (4) The electromagnetic shielding film solution obtained after stirring is evenly coated on the area of ​​the FPC test board that needs to be dynamically bent and cured; wherein, the wet film thickness is 50μm, the curing temperature is 80℃, and the curing time is 20min, and a flexible circuit board with composite electromagnetic shielding film can be obtained.

[0085] Specific production example 2:

[0086] (1) Sample preparation: 13g TPU particles, 25g silver nanowires (AgNW), 60g DMF (dimethylformamide) solvent, and FPC test plate.

[0087] (2) Add TPU particles to DMF solvent at a rate of 1~2g per minute per liter of DMF, and stir at 60°C for 2 hours until the TPU particles are completely dissolved to form a transparent viscous solution, which is the elastic matrix solution.

[0088] (3) Add PVP surfactant to DMF solvent to make the mass content of PVP surfactant 0.2%; dissolve silver nanowires AgNW in DMF solvent containing PVP, and sonicate for 20 min under a power of 300 W to form AgNW slurry, which is a metal conductive solution.

[0089] (4) Add AgNW slurry to TPU solution and add KH-550 silane coupling agent (for surface modification and to reduce agglomeration). Mix evenly according to gradient stirring method. The low-speed stirring process is carried out for initial dispersion at a stirring speed of 200~400 rpm and a stirring time of 10 min. The high-speed shearing process is carried out at a shearing speed of 800~1200 rpm and a shearing time of 30 min to break the agglomeration of silver material components. The vacuum degassing process is carried out at a vacuum pressure of -0.09 MPa and a degassing time of 20 min to form an electromagnetic shielding film solution.

[0090] (5) Using a slit coating method, the electromagnetic shielding film solution obtained after stirring is uniformly coated on the area of ​​the FPC test board that needs to be dynamically bent and then cured; wherein, the wet film thickness is 50μm, and the curing is carried out in two stages. The curing temperature of the first stage is 80℃ and the curing time is 5min, and the curing temperature of the second stage is 120℃ and the curing time is 10min, so that a flexible circuit board with a composite electromagnetic shielding film can be obtained.

[0091] The flexible circuit boards obtained from the two specific manufacturing examples can be mounted on a bending machine. By monitoring the change in the resistance of the electromagnetic shielding film, the bending life of this type of composite electromagnetic shielding film can be obtained. Example 2

[0092] This embodiment provides a flexible circuit board with a composite electromagnetic shielding film, which is manufactured using the method described in Embodiment 1.

[0093] This embodiment utilizes a high-flexibility elastic matrix solution and a high-electromagnetic-shielding metallic conductive solution, combined with a coating process to form a target flexible circuit board. The composite electromagnetic shielding film in this board is less prone to delamination and breakage during dynamic bending applications of FPC products. It can simultaneously meet the increasingly stringent requirements of bendability and lifespan for FPC products, providing significant research value for the future development of dynamic bending of flexible circuit boards. Furthermore, the manufacturing process is simple, the coating shape is customizable, and point-to-point and quantitative coating can be achieved. The coating thickness, area, and surface roughness of the formed film are all controllable, reducing cost waste and facilitating the lightweight and thin design of flexible circuit boards.

[0094] The manufacturing method of the flexible circuit board with composite electromagnetic shielding film in this embodiment is the same as the method described in Embodiment 1. Therefore, for details not covered in this embodiment, please refer to Embodiment 1 and... Figures 1-2 The specific description will not be repeated in this embodiment.

[0095] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method of manufacturing a flexible wiring board having a composite electromagnetic shield film, characterized by, The method comprises: respectively providing an elastic matrix solution and a metal conductive solution; forming an electromagnetic shielding film solution based on the elastic matrix solution and the metal conductive solution; providing a flexible board substrate, and coating the electromagnetic shielding film solution on the flexible board substrate, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, to obtain a target flexible circuit board; forming an electromagnetic shielding film solution based on the elastic matrix solution and the metal conductive solution comprises: adding the elastic matrix solution into the metal conductive solution, and mixing the metal conductive solution and the elastic matrix solution uniformly by using a gradient stirring method, to obtain the electromagnetic shielding film solution; providing an elastic matrix solution comprises: providing an elastic matrix material; the elastic matrix material comprises any one or any combination of polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer polyurethane, thermoplastic polyurethane, and acrylate; dissolving the elastic matrix material in a first organic solvent, so that the elastic matrix material is completely dissolved to form the elastic matrix solution; providing a metal conductive solution comprises: providing a metal conductive material; the metal conductive material comprises any one or any combination of silver, copper, nickel, and aluminum; dissolving the metal conductive material in a second organic solvent, so that the metal conductive material is completely dissolved to form the metal conductive solution.

2. The method of manufacturing according to claim 1, wherein, The gradient stirring method comprises a low-speed stirring process with first process parameters, a high-speed shearing process with second process parameters, and a vacuum defoaming process with third process parameters, and the low-speed stirring process, the high-speed shearing process, and the vacuum defoaming process are executed in sequence. The first process parameters comprise stirring speed and stirring time, the second process parameters comprise shearing speed and shearing time, and the third process parameters comprise vacuum pressure and defoaming time.

3. The method of claim 1, wherein The flexible board substrate is pre-provided with a dynamic bending area; coating the electromagnetic shielding film solution on the flexible board substrate, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, to obtain a target flexible circuit board, comprises: uniformly coating the electromagnetic shielding film solution on the dynamic bending area of the flexible board substrate according to preset coating parameters; performing curing treatment on the flexible board substrate coated with the electromagnetic shielding film solution according to preset curing parameters, so that the electromagnetic shielding film solution on the flexible board substrate forms the composite electromagnetic shielding film, to obtain the target flexible circuit board.

4. The method of manufacturing according to claim 3, wherein, The preset coating parameters comprise wet film thickness, and the preset curing parameters comprise curing temperature and curing time.

5. A flexible wiring board having a composite electromagnetic shield film, characterized by, The target flexible circuit board is made by using the manufacturing method according to any one of claims 1 to 4.

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