Flexible circuit board with composite electromagnetic shielding film and manufacturing method thereof

Abstract

The invention discloses a flexible circuit board with a composite electromagnetic shielding film and a manufacturing method of the flexible circuit board. The method comprises the following steps: 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; and providing a flexible board substrate, and coating the flexible board substrate with the electromagnetic shielding film solution, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, and obtaining a target flexible circuit board. The composite electromagnetic shielding film is not prone to layering breakage in dynamic bending application of an FPC product, the higher and higher requirements of the FPC product for the bending performance and the service life can be met at the same time, the technology is simple, the coating shape can be customized, fixed-point and quantitative coating can be achieved, the coating thickness and area and the surface roughness of the formed film are controllable, and the application range is wide. The cost waste can be reduced, and the design of light weight and thinness of the flexible circuit board is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible circuit board manufacturing, in particular to a flexible circuit board with a composite electromagnetic shielding film and a manufacturing method thereof. BACKGROUND

[0002] Flexible Printed Circuit (FPC) is increasingly widely used in electronic devices due to its lightweight, thinness, excellent flexibility, bendability, high-density connectivity, vibration resistance and impact resistance, etc. With the rapid development of the electronic industry, especially the rise of foldable screen mobile phones, portable and wearable devices, the market size of foldable screen FPC is experiencing rapid growth, and the reliability requirements of FPC are becoming higher and higher.

[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, flexibility and harsh environment, which is usually composed of conductive materials (such as silver, copper, carbon, etc.) and high polymer substrates (such as polyimide PI, polyethylene terephthalate PET, etc.).

[0004] Traditional electromagnetic shielding films usually adopt a three-layer structure of "insulating layer-conductive layer-adhesive layer". This structure is prone to delamination and fracture in the dynamic bending application of FPC products, which further leads to shorter service life of FPC products. Therefore, with the future development of FPC towards higher frequency compatibility (such as THz frequency band), adaptability to extreme environment (such as space electronic environment) and intelligentization (such as self-adaptive tuning shielding), the existing electromagnetic shielding film cannot meet the requirements of higher and higher bendability and service life of FPC products. SUMMARY

[0005] Therefore, the present application provides a flexible circuit board with a composite electromagnetic shielding film and a manufacturing method thereof to solve the problem that the existing electromagnetic shielding film is prone to delamination and fracture in the dynamic bending application of FPC products, which cannot meet the requirements of higher and higher bendability and service life.

[0006] The present application provides a manufacturing method of a flexible circuit board with a composite electromagnetic shielding film, which comprises: 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 substrate, coating the electromagnetic shielding film solution on the flexible substrate, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, and obtaining a target flexible circuit board.

[0007] Optionally, providing the elastomeric matrix solution comprises: providing an elastomeric matrix material; dissolving the elastomeric matrix material in a first organic solvent such that the elastomeric matrix material is completely dissolved, forming the elastomeric matrix solution.

[0008] Optionally, the elastomeric matrix material comprises any one or more of polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, polyurethane, thermoplastic polyurethane, and acrylate.

[0009] Optionally, providing the metal conductive solution comprises: providing a metal conductive material; dissolving the metal conductive material in a second organic solvent such that the metal conductive material is completely dissolved, forming the metal conductive solution.

[0010] Optionally, the metal conductive material comprises any one or more of silver, copper, nickel, and aluminum.

[0011] Optionally, based on the elastomeric matrix solution and the metal conductive solution, forming an electromagnetic shielding film solution comprises: adding the elastomeric matrix solution into the metal conductive solution, and mixing the metal conductive solution and the elastomeric matrix solution uniformly by using a gradient stirring method, to obtain the electromagnetic shielding film solution.

[0012] Optionally, 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. wherein 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.

[0013] Optionally, the flexible board substrate is pre-provided with a dynamic bending area; coating the electromagnetic shielding film solution on the flexible board substrate such that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, to obtain a target flexible circuit board, comprising: uniformly coating the electromagnetic shielding film solution on the dynamic bending area of the flexible board substrate according to pre-set coating parameters; According to the preset curing parameters, the flexible board substrate coated with the electromagnetic shielding film solution is subjected to a curing treatment, so that the electromagnetic shielding film solution on the flexible board substrate forms the composite electromagnetic shielding film, and the target flexible circuit board is obtained.

[0014] Optionally, the preset coating parameters include a wet film thickness, and the preset curing parameters include a curing temperature and a curing time.

[0015] In addition, the application further provides a flexible circuit board with a composite electromagnetic shielding film, which is manufactured by the manufacturing method.

[0016] The application has the following beneficial effects: by mixing the elastic matrix solution and the metal conductive solution, a mixed-state electromagnetic shielding film solution with electromagnetic shielding function is formed, which is coated on the flexible board substrate to form a functional film for inhibiting electromagnetic interference, i.e., the composite electromagnetic shielding film. The film with the mixed-state structure has excellent electromagnetic shielding efficiency and can significantly improve the bendability of the target flexible circuit board, thereby effectively overcoming the influence of the product life caused by the fracture of the electromagnetic shielding film during the dynamic bending application of the flexible circuit board with the composite electromagnetic shielding film. Compared with the traditional three-layer structure electromagnetic shielding film, the composite electromagnetic shielding film provided by the application is not prone to delamination and fracture in the dynamic bending application of the FPC product, and can simultaneously meet the requirements of the increasingly high bendability and life of the FPC product, thereby providing important research value for the development of the dynamic bending of the flexible circuit board in the future. Meanwhile, in the manufacturing process of the flexible circuit board with the composite electromagnetic shielding film, no punching and no tearing-off of the transfer film are required, the process is simple, the coating shape can be self-defined, the fixed-point and fixed-quantity coating can be realized, 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. BRIEF DESCRIPTION OF DRAWINGS

[0017] The features and advantages of the application will be more clearly understood through reference to the following detailed description taken in conjunction with the accompanying drawings, which are illustrative in nature and are not intended to be limiting of the application. In the drawings: Figure 1 A flow chart of a manufacturing method of a flexible circuit board with a composite electromagnetic shielding film in the embodiment one of the application is shown; Figure 2 A sectional view structure diagram of a target flexible circuit board formed in the embodiment one of the application is shown.

[0018] The reference signs are explained as follows: 1, flexible board substrate, 2, composite electromagnetic shielding film, 21, elastic matrix material, 22, metal conductive material. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. Embodiment one

[0020] The present embodiment provides a manufacturing method of a flexible circuit board with a composite electromagnetic shielding film, as shown in the following figure, comprising: Figure 1 S1: providing an elastic matrix solution and a metal conductive solution respectively; S2: forming an electromagnetic shielding film solution based on the elastic matrix solution and the metal conductive solution; S3: providing a flexible board substrate, coating the electromagnetic shielding film solution on the flexible board substrate, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, and obtaining a target flexible circuit board. In the present embodiment, by mixing the elastic matrix solution and the metal conductive solution, a mixed-state electromagnetic shielding film solution with electromagnetic shielding function is formed. This solution forms a functional film for suppressing electromagnetic interference, i.e. a composite electromagnetic shielding film, on the flexible board substrate through coating process. This film with mixed-state structure has excellent electromagnetic shielding efficiency and can significantly improve the bendability of the formed target flexible circuit board, thereby effectively overcoming the impact of electromagnetic shielding film rupture on product life during dynamic bending application of the flexible circuit board with the composite electromagnetic shielding film. Compared with the traditional three-layer structure electromagnetic shielding film, the composite electromagnetic shielding film provided by the present application is not prone to delamination and rupture in the dynamic bending application of FPC products, and can simultaneously meet the requirements of higher and higher bendability and life 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 the flexible circuit board with the composite electromagnetic shielding film, there is no need for punching, no need for tearing off the transfer film, the process is simple, the coating shape can be customized, and fixed-point and fixed-quantity coating can be realized. The 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 the flexible circuit board.

[0021] The following will describe each step of the manufacturing method of the present embodiment in detail.

[0022] Preferably, in S1 of the present embodiment, providing the elastic matrix solution comprises:

[0023] S11: providing an elastic matrix material; S12: dissolving the elastic matrix material in a solvent to obtain the elastic matrix solution. S12: 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.

[0024] The elastic matrix material has high elasticity and is mostly soluble in an organic solvent. By completely dissolving the elastic matrix material in the first organic solvent, subsequent mixing with a metal conductive solution is facilitated, and then a coating process is facilitated to form a high-flexibility electromagnetic shielding film, which is suitable for roll-to-roll mass production. Moreover, the elastic matrix solution formed after complete dissolution exhibits strong adhesion to various substrates (such as PET, PI, and silica gel) in the FPC product, facilitating direct coating to form a firm film and effectively improving product quality.

[0025] Preferably, in S11, the elastic matrix material includes any one or several of polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, polyurethane, thermoplastic polyurethane, and acrylate.

[0026] The polystyrene (PS) hard segment and polyisoprene (PI) soft segment of the polystyrene-isoprene-polystyrene block copolymer (SIS) form spherical, columnar, or lamellar phase separation, giving the material excellent flexibility and tear resistance, with a tensile strength of 17.25-20.7 MPa, an elongation at break of over 1000%, and remaining flexible at -40℃ low temperature environment, suitable for the requirements of repeated stretching of FPC products.

[0027] The styrene-butadiene-styrene block copolymer (SBS) has excellent elastic resistance and deformation resistance, with stable molecular structure, remaining elastic at -30℃ to +50℃ temperature environment, and is also suitable for the high flexibility requirements of FPC products.

[0028] The styrene-ethylene-butylene-styrene block copolymer (SEBS) has stable performance at -60℃ to +120℃ temperature environment, also has excellent elastic resistance and deformation resistance, and is suitable for the high flexibility requirements of FPC products.

[0029] The hardness of polyurethane (PU) can be adjusted from Shore A20 (soft rubber roller) to Shore D70 (hard steel roller), and the elastic performance can be adjusted in a large range. Thermoplastic polyurethane (TPU) also has excellent tensile strength and tear strength, and can adapt to different processing environments. Acrylate can continuously work at 150℃ for 1000h, with a permanent deformation of about 30%, and can resist permanent deformation.

[0030] The above-mentioned elastic matrix materials all have high elasticity, and after film formation, the thin film can be bent, folded or even stretched (the strain can reach 100-300%), effectively improving the flexibility of the thin film, and is extremely suitable for dynamic bending environment of flexible electronics, wearable devices and the like.

[0031] Specifically, in S12, each type of elastic matrix material can select a corresponding suitable type of first organic solvent according to actual conditions.

[0032] For the elastic matrix materials such as polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer and acrylate, the form is mostly solid particle form or block solid form, which can be dissolved in first organic solvents such as toluene, cyclohexane, ethyl acetate, etc., to form a uniform transparent, viscoelastic elastic matrix solution.

[0033] For the elastic matrix materials such as polyurethane and thermoplastic polyurethane, the form is mostly viscous paste form or block solid form, which can be dissolved in first organic solvents such as DMF, THF, acetone, butanone, etc., to form an elastic matrix solution.

[0034] Preferably, in S1 of the embodiment, providing a metal conductive solution comprises: S13: providing a metal conductive material; S14: 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.

[0035] Through complete dissolution of the metal conductive material in the solvent, the formed metal conductive solution can better form a continuous conductive path in the elastic matrix solution, and provide efficient shielding through reflection and absorption of electromagnetic waves, so that through subsequent combination with the elastic matrix solution, on the one hand, it is convenient to adopt a coating process to form a film, and on the other hand, it ensures that the formed thin film not only realizes the electromagnetic shielding function, but also effectively improves the stretchability, thereby improving the dynamic bending life of the electromagnetic shielding film in the application of flexible circuit board.

[0036] Preferably, in S13, the metal conductive material comprises any one or any combination of silver, copper, nickel and aluminum.

[0037] Silver is the best conductive metal, with a surface resistivity of less than 0.010 Ω / cm, and a shielding effectiveness of more than 75 dB in the 10 GHz high frequency range, which can be applied to scenarios with extremely high shielding requirements; the conductivity of copper is only second to silver, with a shielding effectiveness of 75 dB at frequencies above 1 GHz, and the conductivity of copper enables it to effectively reflect high-frequency electromagnetic waves and reduce signal leakage; although the conductivity of nickel is lower than that of silver and copper, its permeability is high, the magnetic vector attenuation amplitude is large, and the electromagnetic interference absorption capacity is strong, with a shielding effectiveness of 60-65 dB in the 5-1800 MHz range, especially in the low frequency range (below 30 MHz); the conductivity of aluminum is better than that of nickel but lower than that of copper and silver, which can effectively block high-frequency electromagnetic waves, and its lightweight characteristics (density is only 1 / 3 of copper) make it have an advantage in scenarios where weight reduction is required, and it can maintain a low cost and weight. Through the above metal conductive materials, the combination of high- flexibility elastic matrix solution + high electromagnetic shielding metal conductive solution in the subsequent process can ensure the stretchability of the electromagnetic shielding film in the FPC product, and at the same time meet the increasingly high requirements of the FPC product for bendability and service life.

[0038] 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 sequential execution is not limited.

[0039] Specifically, in S14, the second organic solvent for dissolving the metal conductive material can be selected according to actual conditions, such as ethanol, ethylene glycol, and toluene, etc.

[0040] Preferably, the S2 of the embodiment includes: The elastic matrix solution is added to the metal conductive solution, and a gradient stirring method is used to mix the metal conductive solution and the elastic matrix solution uniformly to obtain the electromagnetic shielding film solution.

[0041] During the mixing process of the metal conductive solution and the elastic matrix solution, a gradient stirring method including three processes (i.e., a low-speed stirring process, a high-speed shearing process, and a vacuum degassing process) is used to eliminate defects between the interfaces of the two solutions, realize effective dispersion between the two solutions, avoid brittleness caused by rigid fillers (materials in the metal conductive solution), enable the metal conductive solution and the elastic matrix solution to be fully mixed, improve the bonding force between the metal conductive material and the elastic matrix material in the solution, and thus ensure that the formed electromagnetic shielding film solution has excellent electromagnetic shielding and flexibility.

[0042] Specifically, 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.

[0043] The low-speed stirring can preliminarily disperse the two material solutions of the metal conductive solution and the elastic matrix solution; the high-speed shearing can break the agglomeration of the conductive material in the metal conductive solution, so that the metal conductive solution is uniformly and stably dispersed into the elastic matrix solution; and the vacuum defoaming can make the gas in the mixed solution escape due to physical expansion, so that a defect-free and uniform electromagnetic shielding film solution is obtained.

[0044] Specifically, 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.

[0045] In the above three processes, by respectively controlling the above process parameters, the expected effects of the processes can be ensured, thereby effectively guaranteeing the quality of the electromagnetic shielding film solution.

[0046] Preferably, in the embodiment S3, the flexible board substrate is provided with a dynamic bending area in advance; In S3, the electromagnetic shielding film solution is coated on the flexible board substrate, so that the electromagnetic shielding film solution forms a composite electromagnetic shielding film, and a target flexible circuit board is obtained, comprising: S31: uniformly coating the electromagnetic shielding film solution on the dynamic bending area of the flexible board substrate according to preset coating parameters; S32: 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, and the target flexible circuit board is obtained.

[0047] The coating according to the preset coating parameters can make the electromagnetic shielding film solution uniformly cover the dynamic bending area of the flexible board substrate, and realize point and quantitative coating according to self-definition, so that the coating thickness and area are controllable, which is conducive to reducing cost and waste; and the curing treatment according to the preset curing parameters can ensure that the electromagnetic shielding film solution on the dynamic bending area is efficiently formed into a film, thereby improving the quality of the composite electromagnetic shielding film.

[0048] Specifically, the flexible board substrate of the embodiment refers to an FPC semi-finished product to be made into an electromagnetic shielding film, which has completed the conventional processes such as line forming, reinforcing, chemical nickel gold plating, etc. in the FPC manufacturing process, and specific details are not described here.

[0049] Specifically, the preset coating parameter includes a wet film thickness, and the preset curing parameter includes a curing temperature and a curing time.

[0050] By the preset coating parameter and the preset curing parameter, the composite electromagnetic shielding film required to be formed on the flexible substrate can be efficiently ensured, and the FPC product capable of simultaneously satisfying the requirements of high bendability and service life can be formed.

[0051] Specifically, the coating in the embodiment includes, but is not limited to, blade coating and spin coating.

[0052] The cross-sectional structure of the target flexible circuit board formed by the embodiment is shown in Figure 2 , wherein Figure 2 1 is a flexible substrate, 2 is a composite electromagnetic shielding film, 21 is an elastic matrix material in the composite electromagnetic shielding film, and 22 is a metal conductive material in the composite electromagnetic shielding film.

[0053] To further show the specific details in the manufacturing process, the embodiment provides the following two specific manufacturing examples.

[0054] Specific manufacturing example 1: (1) Sample preparation: 100 g of SIS solution, 27 g of flaky silver powder, and an FPC test board.

[0055] (2) The flaky silver powder is dispersed in a solvent (such as water, ethanol, ethylene glycol, toluene, etc.), and an appropriate amount of a surfactant (such as polyvinylpyrrolidone PVP, polyvinyl alcohol PVA, etc.) or a dispersant (such as a sulfonate dispersant) is added to stabilize the suspension and prevent agglomeration, forming a silver paste, which is a gray-black or dark gray viscous liquid, that is, a metal conductive solution.

[0056] (3) The silver paste is gradually added to the SIS solution (which is an elastic matrix solution), and is uniformly mixed according to a gradient stirring method, wherein the low-speed stirring process is performed according to a stirring speed of 200-400 rpm and a stirring time of 10 min for preliminary dispersion; the high-speed shearing is performed according to a shearing speed of 800-1200 rpm and a shearing time of 30 min to break the agglomeration of the silver material components; and the vacuum degassing process is performed according to a vacuum pressure of -0.09 MPa and a degassing time of 20 min, so that the solid content in the electromagnetic shielding film solution formed is 33%.

[0057] (4) 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 is cured; wherein the wet film thickness is 50 μm, the curing temperature is 80°C, and the curing time is 20 min, so that the flexible circuit board with the composite electromagnetic shielding film can be obtained.

[0058] Specific manufacturing example 2: (1) Sample preparation: TPU particles 13 g, silver nanowires (AgNW) 25 g, DMF (dimethylformamide) solvent 60 g, FPC test board.

[0059] (2) In the DMF solvent, add TPU particles at a rate of 1-2 g per liter of DMF per minute, and stir at a temperature of 60°C for 2 hours until the TPU particles are completely dissolved, forming a transparent viscous solution TPU solution, which is the elastic matrix solution.

[0060] (3) Add PVP surfactant to the DMF solvent, so that the mass content of PVP surfactant in it is 0.2%; dissolve silver nanowires AgNW in the PVP-containing DMF solvent, and ultrasonic treat under the condition of power 300 W for 20 min, forming an AgNW slurry, which is a metal conductive solution.

[0061] (4) Add the AgNW slurry to the TPU solution and add KH-550 silane coupling agent (which has a surface modification effect and reduces agglomeration), and mix uniformly according to the gradient stirring method, wherein the low-speed stirring process is carried out at a stirring speed of 200-400 rpm and a stirring time of 10 min for preliminary dispersion; high-speed shearing 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; 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; (5) Using the slot 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 is cured; wherein the wet film thickness is 50 μm, and the curing is carried out in two stages, the first stage curing temperature is 80°C, and the curing time is 5 min, the second stage curing temperature is 120°C, and the curing time is 10 min, so that the flexible circuit board with composite electromagnetic shielding film is obtained.

[0062] The flexible circuit boards obtained from the two specific manufacturing examples can be mounted on a bending machine, and by monitoring the resistance change of the electromagnetic shielding film, the bending life of this type of composite electromagnetic shielding film is obtained. Example Two

[0063] This embodiment provides a flexible circuit board with a composite electromagnetic shielding film, which is made by the manufacturing method described in Example One.

[0064] The target flexible circuit board is formed by combining a high-flexibility elastic base solution and a metal conductive solution with high electromagnetic shielding performance and a coating process. The composite electromagnetic shielding film is not prone to delamination and fracture in the dynamic bending application of the FPC product, and can simultaneously meet the requirements of higher bendability and service life of the FPC product, thereby providing important research value for the development of the dynamic bending of the flexible circuit board in the future. Meanwhile, the manufacturing process is simple, the coating shape can be self-defined, the fixed-point and fixed-quantity coating can be realized, 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.

[0065] The manufacturing method of the flexible circuit board with the composite electromagnetic shielding film in the embodiment is the same as the method steps described in Embodiment 1, and thus the details of the embodiment are described in detail in Embodiment 1 and the specific description of Figures 1-2 , and the embodiment will not be described again.

[0066] Although the embodiments of the present application are described in combination with the drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the present application, 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.

2. The production method according to claim 1, characterized by, The providing of the elastic matrix solution comprises: providing an elastic matrix material; 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.

3. The method of manufacturing according to claim 2, wherein, The elastic matrix material comprises any one or several of polystyrene-isoprene-polystyrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer polyurethane, thermoplastic polyurethane, and acrylate.

4. The method of making of claim 1, wherein, The providing of the metal conductive solution comprises: providing a metal conductive material; 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.

5. The method of manufacturing according to claim 4, wherein, The metal conductive material comprises any one or several of silver, copper, nickel, and aluminum.

6. The method of making of claim 1, wherein, The forming of the 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.

7. The method of manufacturing according to claim 6, 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.

8. The method of making of claim 1, wherein, The flexible board substrate is pre-provided with a dynamic bending area; The coating of 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 pre-set coating parameters; performing curing treatment on the flexible board substrate coated with the electromagnetic shielding film solution according to pre-set 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.

9. The method of manufacturing according to claim 8, wherein, The pre-set coating parameters comprise wet film thickness, and the pre-set curing parameters comprise curing temperature and curing time.

10. 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 9.

Images