A high-permeability multilayer flexible soft magnetic thin film, its preparation method and application

Abstract

This invention provides a high-permeability multilayer flexible soft magnetic film, its preparation method, and its applications. The multilayer flexible soft magnetic film is composed of alternating layers of magnetic metal layers and polymer insulating dielectric layers. Each magnetic metal layer is precisely controlled to be 200–900 nm thick, and each polymer insulating dielectric layer is controlled to be 100–500 nm thick, with the total thickness of the magnetic metal layers accounting for 30%–80%. Through this structural design, the polymer insulating dielectric layer effectively blocks interlayer eddy current paths, significantly suppressing high-frequency eddy current losses. Simultaneously, the high proportion of magnetic layers provides sufficient magnetic flux and magnetic loss contribution, avoiding insufficient magnetic performance due to excessively thick insulating layers or exacerbated eddy current losses due to excessively thick magnetic layers. Therefore, the imaginary peak value of the film's effective permeability is greater than 400, exhibiting excellent high-frequency magnetic loss, wave absorption, and noise suppression capabilities. Furthermore, the structure is stable and flexible, making it suitable for high-frequency filtering, electromagnetic compatibility, and other applications.

Description

Technical Field

[0001] This invention relates to the field of magnetic absorbing thin film materials technology, specifically to a high-permeability multilayer flexible soft magnetic thin film, its preparation method and application, and is particularly suitable for high-frequency electronic devices, microwave absorbing materials and electromagnetic shielding. Background Technology

[0002] With the rapid development of electronic devices such as mobile communications, IoT sensors, and automotive electronics, the demand for high-frequency, highly integrated, and high-performance magnetic devices is becoming increasingly urgent. Flexible magnetic metal thin films, with their advantages of high permeability, good flexibility, and high integration adaptability, are widely used in high-frequency fields such as microwave filtering, noise suppression, and electromagnetic wave absorption, and also show great application potential in flexible sensing and electronic skin. However, magnetic metal thin films experience significant eddy current losses under high-frequency alternating magnetic fields, causing a rapid decrease in permeability. Furthermore, due to the skin effect, simply increasing the film thickness has limited effectiveness, making it difficult to simultaneously achieve high high-frequency permeability and suitable magnetic loss levels.

[0003] Existing technologies typically involve introducing insulating media into magnetic materials to form nanoparticle films, or fabricating multilayer film structures by placing non-magnetic insulating layers between magnetic layers, in order to improve the resistivity of the system and suppress in-plane and interlayer eddy currents. Among these, nanoscale multilayer film structures can block eddy current paths by utilizing nanoscale insulating media layers, thereby achieving superior high-frequency magnetic properties and showing promising application prospects in fields such as electromagnetic compatibility.

[0004] Currently, nanoscale magnetic multilayer films are mostly prepared using vacuum deposition methods such as magnetron sputtering, molecular beam epitaxy, and atomic layer deposition. These methods produce high-quality, uniform films with a high proportion of magnetic materials, effectively suppressing interlayer eddy currents and maintaining high permeability even at micrometer-thickness levels through interlayer exchange coupling. For example, patent CN202110586639.2 describes the alternating deposition of FeNi and SiO2 multilayer films on a flexible substrate using magnetron sputtering. The resulting film, with a thickness of 0.7 μm, exhibits an imaginary part of permeability of 630 at 0.7 GHz. However, vacuum deposition processes generally suffer from slow deposition rates and high production costs, particularly when preparing thicker, high-permeability magnetic films. Furthermore, during prolonged deposition, plasma and high-energy particles continuously transfer heat to the flexible PET substrate. Since heat dissipation is slow in a vacuum environment, the substrate is prone to deformation due to accumulated thermal stress, affecting film quality and device stability. Therefore, current technology still lacks an effective method for rapidly and cost-efficiently preparing high-permeability multilayer flexible soft magnetic films.

[0005] Electroplating offers advantages such as rapid deposition rates and low raw material and process costs, making it suitable for the efficient preparation of thick magnetic films. For example, patent CN202410046253.6 describes an electroplating method for preparing iron-nickel films, achieving a film thickness of approximately 850 nm in just one minute. Furthermore, the electroplating solution system is inexpensive, making it suitable for large-scale production. Related literature also describes pulsed electrodeposition for preparing Ni... 45 Fe 55 Studies on thin films have shown that when the film thickness increases from 1 μm to 5 μm, the permeability resonance peak shifts significantly to lower frequencies due to the eddy current effect; the imaginary part of the permeability decreases from 1000 to 400 at 0.1 GHz. This indicates that the thickness of a single electroplated magnetic layer should ideally be controlled at around 500 nm. However, this has significant limitations in applications requiring high permeability and film thickness, such as those demanding electromagnetic compatibility. Therefore, an insulating spacer layer needs to be introduced to mitigate the eddy current problem.

[0006] However, due to limitations in the process principle, electroplating cannot directly deposit an insulating layer, making it difficult to directly achieve a multilayer structure with alternating magnetic and insulating layers. Existing technologies use 5μm double-sided adhesive as a spacer layer, alternately layered with a 1.7μm electroplated FeNiCo magnetic film to prepare multilayer films, but this has significant drawbacks: firstly, the relatively thick magnetic layer reduces the imaginary resonance peak of the permeability to below 0.1GHz, limiting high-frequency application performance; secondly, the spacer layer thickness is much greater than the magnetic layer thickness, resulting in a magnetic layer ratio of only 25% and an overall low effective permeability.

[0007] In summary, existing technologies struggle to simultaneously achieve low-cost, rapid fabrication, high magnetic layer ratio, and excellent high-frequency permeability. Therefore, there is an urgent need to develop a simple, low-cost, multilayer flexible soft magnetic thin film with both high permeability and good high-frequency performance, along with its fabrication method. Summary of the Invention

[0008] The purpose of this invention is to provide a multilayer flexible soft magnetic film with high magnetic permeability, its preparation method and application, to solve the technical problems of high preparation cost, low efficiency, large eddy current loss and poor magnetic permeability of existing multilayer flexible soft magnetic films.

[0009] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a multilayer flexible soft magnetic film with high magnetic permeability, comprising at least two magnetic metal layers and at least one polymer insulating dielectric layer alternately stacked, wherein each polymer insulating dielectric layer is sandwiched between two adjacent magnetic metal layers. The thickness of each magnetic metal layer is 200–900 nm, the thickness of each polymer insulating dielectric layer is 100–500 nm, and the total thickness of the multilayer magnetic metal layers accounts for 30%–80% of the thickness of the multilayer flexible soft magnetic film; the peak value of the imaginary part of the effective magnetic permeability of the multilayer flexible soft magnetic film is greater than 400.

[0010] Specifically, by controlling the total thickness of the multilayer magnetic metal layers to be between 30% and 80%, this invention effectively blocks interlayer eddy current paths and significantly suppresses high-frequency eddy current losses through the polymer insulating dielectric layer, while ensuring a sufficiently high proportion of magnetic materials and magnetic flux contribution. This allows the thin film to achieve an effective permeability peak value greater than 400, demonstrating excellent high-frequency magnetic loss and wave absorption and noise suppression capabilities. At the same time, the polymer insulating dielectric layer has good flexibility, adhesion, and acid and alkali resistance, which can effectively buffer the stress generated during sputtering and electroplating processes, preventing the film from cracking, breaking, or delaminating. This achieves rapid and low-cost preparation while ensuring the stability of the thin film structure and reliable performance.

[0011] Preferably, the number of magnetic metal layers in the multilayer flexible soft magnetic film is 2 to 20.

[0012] Specifically, a layer count of 2 to 20 layers achieves the optimal balance between magnetic properties, structural stability, and fabrication economy. Too few layers result in insufficient overall magnetic flux, making it difficult to guarantee an imaginary peak value greater than 400 for effective permeability; too many layers not only significantly increase processing steps and fabrication costs but also easily lead to stress accumulation in the film layers and insulation layer failure. Employing an alternating structure of 2 to 20 layers ensures sufficient magnetic flux and excellent high-frequency magnetic loss capability through multilayer stacking, while effectively controlling processing difficulty and film defects. This results in multilayer flexible soft magnetic films that possess a high imaginary permeability while exhibiting greater structural stability and more efficient fabrication.

[0013] Preferably, the magnetic metal layer includes a conductive seed layer and an electroplated magnetic layer stacked from bottom to top; the conductive seed layer is a conductive metal or an organic conductive polymer, the conductive metal is selected from at least one of iron, nickel, iron-nickel alloy, copper or molybdenum, and the organic conductive polymer is selected from polypyrrole or polyaniline; the electroplated magnetic layer is selected from at least one of iron, nickel, cobalt, iron-nickel alloy, iron-cobalt alloy or iron-nickel-cobalt alloy.

[0014] Specifically, the conductive seed layer is not limited to magnetic materials; it only needs to meet conductivity requirements. Conductive metals such as copper and molybdenum, or conductive polymers such as polypyrrole and polyaniline, can be used. This ensures conductivity and adhesion while broadening the range of material choices, reducing material costs and process complexity, and allowing for good compatibility with the upper electroplated magnetic layer. Furthermore, introducing an ultra-thin conductive seed layer significantly improves the conductivity of the substrate surface and the adhesion of the electroplated magnetic layer, providing a uniform and continuous conductive path for the subsequent electroplating of the magnetic layer. This ensures a uniform electric field distribution during electroplating and avoids defects such as incomplete plating, pinholes, roughness, or poor adhesion in the electroplated magnetic layer. Simultaneously, the aforementioned magnetic materials possess both high saturation magnetization and good soft magnetic properties, ensuring both the conductivity and nucleation ability of the conductive seed layer and enabling the electroplated magnetic layer to acquire excellent magnetic properties.

[0015] Preferably, the polymer insulating dielectric layer is a flexible polymer layer prepared by dip-coating method, and the material is selected from polyvinyl butyral or polymethyl methacrylate.

[0016] Specifically, the polymer insulating dielectric layer is prepared using the dip-coating method, selecting water-resistant and acid- and alkali-resistant polyvinyl butyral (PVB) or polymethyl methacrylate (PMMA) polymer materials. This method is not only simple, rapid, and inexpensive, but also allows for precise control of the film thickness to suit the overall structural design. Furthermore, its excellent flexibility and interfacial adhesion effectively buffer coating stress, prevent film damage and cracking, and reliably block eddy current paths. At the same time, its excellent resistance to electroplating solution corrosion ensures the stability of the multilayer structure. Without significantly reducing the proportion of magnetic layer thickness, it truly achieves a balance between low-cost preparation and excellent high-frequency magnetic performance.

[0017] Secondly, the present invention also provides a method for preparing a multilayer flexible soft magnetic thin film with high magnetic permeability, the method comprising the following steps: S10, a conductive seed layer is prepared on the substrate, and an electroplated magnetic layer is deposited on the conductive seed layer by electroplating to obtain a magnetic metal layer with a thickness of 200-900 nm. S20, the obtained structure is immersed in a flexible polymer solution, and a polymer insulating dielectric layer with a thickness of 100-500 nm is formed by dip-coating method; S30, repeat steps S10 to S20 to obtain a multilayer flexible soft magnetic film with alternating layers of magnetic metal layer and polymer insulating dielectric layer. Each polymer insulating dielectric layer is sandwiched between two adjacent magnetic metal layers, and the total thickness of the magnetic metal layers accounts for 30% to 80% of the total thickness of the multilayer flexible soft magnetic film; the peak value of the imaginary part of the effective magnetic permeability of the multilayer flexible soft magnetic film is greater than 400.

[0018] Specifically, this invention employs a combined electroplating and dip-coating process to obtain multilayer flexible soft magnetic films. Electroplating rapidly deposits the magnetic metal layer, ensuring high film formation rate and low raw material and process costs, effectively solving the problems of low efficiency and high cost associated with traditional vacuum deposition. Simultaneously, the dip-coating process is used to prepare a polymer insulating dielectric layer in situ, offering a simple process with controllable thickness, eliminating the need for complex vacuum equipment, and allowing for efficient integration with the electroplating process. The combined use of these two methods not only suppresses high-frequency eddy current losses through alternating layer structures, resulting in an effective permeability peak value greater than 400, but also controls the total thickness of the magnetic metal layer to within 30%–80%. This achieves rapid, low-cost, and scalable fabrication while maintaining excellent high-frequency magnetic properties and structural stability, significantly outperforming single vacuum deposition or single electroplating processes.

[0019] Preferably, in step S10, the method for preparing the conductive seed layer is selected from one of magnetron sputtering, chemical vapor deposition, atomic layer deposition, or electroless plating.

[0020] Specifically, the conductive seed layer can be prepared using mature processes such as magnetron sputtering, chemical vapor deposition, atomic layer deposition, or electroless plating. The resulting film is uniform and dense with excellent adhesion, providing a stable and uniform conductive substrate for subsequent electroplating. At the same time, these methods are highly controllable and widely applicable, and can be flexibly selected according to requirements, ensuring the quality of the ultrathin seed layer without significantly increasing the overall preparation cost.

[0021] Preferably, in step S10, the conductive seed layer is prepared by magnetron sputtering on the substrate for 3–15 min; the electroplated magnetic layer is an iron-nickel-cobalt alloy, and the process conditions for depositing the electroplated magnetic layer are: pH value of the electroplating solution 2–5, electroplating temperature 20–50℃, and pulse current density 1–2 A / dm³. 2 .

[0022] Specifically, if the conductive seed layer is too thin, it will easily cause discontinuity and uneven thickness of the electroplated magnetic layer; if it is too thick, it will increase the interfacial stress, reduce the proportion of the electroplated magnetic layer and increase the cost. Only an appropriate thickness can ensure uniform and stable electroplating. The above electroplating process conditions can stably deposit a magnetic layer with uniform thickness and high density in a short time. It can accurately achieve the target coating thickness and avoid problems such as excessive coating stress, coarse grains, pinholes and poor adhesion caused by excessive current, excessive time or improper pH / temperature. It ensures the stability of the magnetic properties of the magnetic layer and makes the peak value of the imaginary part of the effective magnetic permeability of the thin film stably greater than 400, further improving the preparation efficiency and protecting the flexible substrate and the insulating layer.

[0023] Preferably, in step S20, the flexible polymer solution is prepared by mixing a flexible polymer with an organic solvent at a mass fraction of 5-20 wt%, and the lifting speed of the immersion lifting method is 10-480 mm / min. The flexible polymer is polyvinyl butyral or polymethyl methacrylate, and the organic solvent is selected from at least one of ethanol, ethyl acetate, and butyl acetate.

[0024] Specifically, by controlling the polymer solution mass fraction at 5–20 wt% and using a pulling speed of 10–480 mm / min, the film thickness and mechanical properties of the polymer insulating dielectric layer can be precisely controlled. While ensuring the polymer insulating dielectric layer thickness is 100–500 nm, it also possesses good flexibility, adhesion, and corrosion resistance. This process parameter range can effectively balance film thickness and structural stability, reliably blocking eddy currents and maintaining a high proportion of magnetic layers, while also buffering coating stress and preventing film damage.

[0025] Preferably, in step S30, the number of magnetic metal layers in the multilayer flexible soft magnetic film is 2 to 20.

[0026] Specifically, controlling the number of magnetic metal layers to 2 to 20 layers can ensure sufficient magnetic flux and an effective permeability peak value greater than 400, while avoiding stress accumulation, process complexity, and cost increases caused by too many layers, thus balancing magnetic properties, structural stability, and fabrication economy.

[0027] Thirdly, the present invention also provides an application of the multilayer flexible soft magnetic film as described in any of the above claims. The multilayer flexible soft magnetic film is applied in the field of high-frequency electronic devices or the field of 5G communication electromagnetic compatibility. The high-frequency electronic devices include at least one of microwave filters, noise suppression sheets, and flexible sensors.

[0028] Specifically, the multilayer flexible soft magnetic film provided by this invention has excellent magnetic permeability, high-frequency magnetic properties and flexible bendability. It can significantly suppress high-frequency noise and improve electromagnetic shielding and absorption effects. It can meet the stringent requirements of 5G communication and high-frequency microwave devices for electromagnetic compatibility, thinness, flexibility and high-frequency stability. It is suitable for microwave filters, noise suppression sheets, flexible sensors and other devices, and broadens the application range of soft magnetic materials in the field of high frequency and flexible electronics.

[0029] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention provides a high-permeability multilayer flexible soft magnetic film, its preparation method, and its applications. The multilayer flexible soft magnetic film achieves this by precisely controlling the thickness of each magnetic metal layer to 200–900 nm and the thickness of each polymer insulating dielectric layer to 100–500 nm, while strictly ensuring that the total thickness of the multilayer magnetic metal layers accounts for 30%–80% of the total thickness of the multilayer flexible soft magnetic film. This allows the polymer insulating dielectric layer to effectively block eddy current paths between adjacent magnetic metal layers, significantly suppressing high-frequency eddy current losses. Simultaneously, the high proportion of magnetic metal layers provides sufficient magnetic flux and magnetic loss contribution, thus avoiding the problem of insufficient magnetic content and decreased magnetic performance due to excessively thick polymer insulating dielectric layers. It also prevents excessively thick magnetic metal layers from exacerbating eddy current losses. This results in an excellent range where the imaginary peak value of the effective permeability of the multilayer flexible soft magnetic film is greater than 400, fully utilizing its high-frequency magnetic loss, wave absorption, and noise suppression capabilities. Ultimately, a high-permeability multilayer flexible soft magnetic film is obtained, possessing excellent high-frequency magnetic performance, good structural stability, and flexibility, and is suitable for practical applications such as high-frequency filtering and electromagnetic compatibility. Attached Figure Description

[0030] Figure 1A This is a schematic diagram of the structure of the high permeability multilayer flexible soft magnetic thin film provided in Example 1; Figure 1B This is a flowchart of the preparation method of the high magnetic permeability multilayer flexible soft magnetic thin film provided in Example 1; Figure 2 This is a scanning electron microscope (SEM) comparison of the thickness of the multilayer flexible soft magnetic film prepared in Example 1 and the magnetic film prepared in Comparative Example 1. Figure 3A This is a scanning electron microscope (SEM) image of the polymer insulating dielectric layer in the multilayer flexible soft magnetic film prepared in Example 2; Figure 3B This is a scanning electron microscope (SEM) image of the polymer insulating dielectric layer in the multilayer magnetic thin film prepared in Comparative Example 3. Figure 4 The imaginary part (μ'') of the permeability of the multilayer flexible soft magnetic films prepared in Examples 1-3 and the magnetic films prepared in Comparative Examples 1-3 are measured in the full frequency band from 0.1 to 2.5 GHz. Figure 5 A photograph of the damaged polymer insulating dielectric layer in the multilayer magnetic film provided for Comparative Example 4. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention addresses the inherent high cost and low efficiency of existing vacuum thin-film deposition methods for preparing high-permeability multilayer flexible soft magnetic films. It provides a rapid and low-cost method for preparing high-permeability multilayer flexible soft magnetic films, as detailed below: To address the high cost and low efficiency of existing vacuum thin film deposition methods, this invention first employs electroplating to prepare a magnetic metal layer, and simultaneously uses a dip-coating method to prepare a polymer insulating dielectric layer. However, in practical implementation, it was found that to ensure high frequency and high permeability of the film, the thickness of the magnetic metal layer prepared by electroplating is typically no more than 500 nm, while the insulating layer obtained by the traditional dip-coating method is generally thicker. This leads to a low proportion of magnetic metal layer, reduced effective permeability, and the insulating layer is easily damaged during subsequent deposition processes, thus affecting the overall quality of the multilayer thin film. Therefore, this invention further improves upon these problems by employing specific process parameters and formulations to prepare a thinner, high-quality insulating layer, ultimately achieving the fabrication of a multilayer flexible soft magnetic thin film with high magnetic layer proportion and high permeability.

[0033] Specifically, the specific preparation principle and implementation basis of the above-mentioned multilayer flexible soft magnetic thin film are as follows: The thickness of the polymer insulating dielectric layer has a significant impact on the magnetic properties of the thin film: when the polymer insulating dielectric layer is too thin, the interlayer coupling is too strong, which leads to the deterioration of high-frequency magnetic properties. Furthermore, during the subsequent magnetron sputtering of the conductive seed layer, it is prone to cracking or damage due to sputtering stress and insufficient adhesion of the dielectric layer. When the polymer insulating dielectric layer is too thick, the overall magnetic layer ratio of the thin film decreases, and even if the total film thickness remains unchanged, it is difficult to achieve ideal magnetic loss performance. Therefore, controlling the thickness of the polymer insulating dielectric layer and balancing the mechanical stress generated by the conductive seed layer are key to the realization of this invention. Simultaneously, since the preparation process uses electroplating, the introduced polymer insulating dielectric layer must also possess water resistance and acid / alkali resistance to prevent dissolution and damage by the electroplating solution.

[0034] Based on the above principles, the core implementation method of this invention is as follows: the main coating process uses electroplating to quickly prepare the magnetic metal layer, while the polymer insulating dielectric layer is prepared by dip-coating. This method can quickly form a polymer insulating dielectric layer on the surface of the magnetic metal layer that is fast-drying, has controllable thickness, and excellent flexibility. This layer can effectively isolate the magnetic metal layer and increase the proportion of the magnetic layer, thereby improving the magnetic loss capability of the film. Compared with the preparation of multilayer films entirely by magnetron sputtering, this method has higher preparation efficiency and lower cost.

[0035] It should be noted that when preparing multilayer flexible soft magnetic films by electroplating, a thin conductive seed layer needs to be deposited on the flexible polymer film substrate using magnetron sputtering. During magnetron sputtering, the atomic clusters generated by argon gas impacting the target material are deposited on the substrate surface, which will generate significant stress. At the same time, during the electroplating process, when metal ions are reduced to atoms at the cathode and embedded in the lattice, they will change from a loose adsorption state to a close arrangement. The shortening of the interatomic spacing leads to the compression of the lattice, which in turn generates crystallization shrinkage stress.

[0036] To address the aforementioned stress issues, the dip-coating polymer used in this invention possesses high flexibility and adhesion, acting as a stress buffer during sputtering without altering the structure and grain size of the deposited atoms. For example, the selected PVB polymer has a long molecular chain structure, and its ether and acetal bonds provide internal rotational freedom, resulting in a lower glass transition temperature and thus making the prepared insulating film flexible and highly impact-resistant. Simultaneously, the small number of hydroxyl groups in the PVB polymer can form strong hydrogen bonds with the surface of the magnetic metal substrate, providing excellent adhesion and effectively preventing delamination or peeling. Furthermore, the dip-coating polymer used in this invention also exhibits good acid and alkali resistance and is insoluble in water, preventing corrosion and dissolution by the electroplating solution, while also buffering the stress generated by the electroplated magnetic layer.

[0037] According to the classic Landau-Levich (LL) theory, the film thickness h of the polymer layer is mainly determined by the viscosity η of the liquid and the pulling speed ν, where the viscosity depends on factors such as the type and concentration of the polymer and the type of solvent. Therefore, this invention achieves precise control of the polymer insulating dielectric layer thickness by accurately controlling parameters such as the polymer type, polymer concentration, and pulling speed of the flexible polymer solution, thereby optimizing interlayer coupling strength and improving magnetic loss efficiency. Furthermore, the polymer insulating dielectric layer prepared by the above method can have its thickness controlled within the range of 100–500 nm by controlling the polymer molecular weight, pulling speed, and solution concentration. This thickness can withstand the stress generated during subsequent coating or bending processes without cracking or damage.

[0038] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and are not intended to limit the scope of protection of the present invention to the parameter ranges of the following embodiments. Unless otherwise specified, the reagents or instruments used in the present invention are all conventional products that can be purchased through commercial channels.

[0039] Example 1 (lifting speed is 15mm / min): In the first aspect, Embodiment 1 provides a multilayer flexible soft magnetic film with high magnetic permeability, comprising at least two magnetic metal layers and at least one polymer insulating dielectric layer alternately stacked, wherein each polymer insulating dielectric layer is sandwiched between two adjacent magnetic metal layers. The total thickness of the multilayer magnetic metal layer accounts for 30% to 80% of the thickness of the multilayer flexible soft magnetic film, and the number of magnetic metal layers in the multilayer flexible soft magnetic film is 4.

[0040] In Example 1, each magnetic metal layer includes a conductive seed layer and an electroplated magnetic layer stacked from bottom to top; wherein the conductive seed layer is made of Ni. 80 Fe 20 The thickness is 50nm; the electroplated magnetic layer is made of Fe-Ni-Co alloy prepared by electroplating method, with a thickness of 450nm.

[0041] In Example 1, the polymer insulating dielectric layer was prepared by dip-coating method, and its material was polyvinyl butyral (molecular weight of 40,000 to 70,000) with an average thickness of 300 nm.

[0042] Secondly, Example 1 also provides a method for preparing a multilayer flexible soft magnetic film with high magnetic permeability. The structure and specific preparation steps of the multilayer flexible soft magnetic film are described in detail below. Figure 1A and Figure 1B As shown: Step (1) Selecting a substrate: Take a PET (polyethylene terephthalate) substrate with a thickness of 5μm as the substrate for preparing multilayer flexible soft magnetic films.

[0043] Step (2) Preparation of electroplating seed layer: Ni is deposited on the surface of PET substrate by magnetron sputtering. 80 Fe 20 The alloy was sputtered for approximately 6 minutes to form a 50 nm conductive seed layer.

[0044] Step (3) Electroplating to prepare the electroplated magnetic layer: First, the PET substrate with the deposited conductive seed layer is immersed in the electroplating solution, which consists of: 0.06 mol / L ferrous sulfate heptahydrate, 0.6 mol / L nickel sulfate hexahydrate, 0.06 mol / L nickel chloride, and 0.06 mol / L cobalt chloride; then, the pH of the electroplating solution is adjusted to 3.5, and the temperature of the electroplating solution is controlled at 30℃; finally, using the PET substrate as the cathode and the platinum electrode as the anode, 2A / dm² is applied. 2 With a pulsed current density and an electroplating time of 90s, a 450nm Fe-Ni-Co alloy electroplated magnetic layer was formed on the surface of the conductive seed layer.

[0045] Step (4) Preparation of polymer insulating dielectric layer: The electroplated PET substrate is immersed in a 5.2 wt% polyvinyl butyral (PVB, molecular weight 40,000-70,000) / ethanol solution and is wetted and pulled into a film at a pulling speed of 15 mm / min. After film formation, it is dried for 10 min to obtain a polymer insulating dielectric layer with an average thickness of 300 nm.

[0046] Step (5) Cyclic operation to prepare multilayer flexible soft magnetic film: Repeat steps (2), (3) and (4) above multiple times, cycle 3 times, to obtain multilayer flexible soft magnetic film. The morphology of the obtained multilayer flexible soft magnetic film is as follows. Figure 2 As shown in the left figure, the number of magnetic metal layers in the multilayer flexible soft magnetic film is 4.

[0047] Example 2 (lifting speed 30mm / min): Example 2 provides a high permeability multilayer flexible soft magnetic film and its preparation method. The preparation method is largely the same as the preparation method of the high permeability multilayer flexible soft magnetic film provided in Example 1, except for step (4): Step (4) Preparation of the polymer insulating dielectric layer: The electroplated PET substrate was immersed in a 5.2 wt% polyvinyl butyral (PVB, molecular weight 40,000-70,000) / ethanol solution, and the film was formed by wetting and pulling at a pulling speed of 30 mm / min. After film formation, it was dried for 10 min to obtain a polymer insulating dielectric layer with an average thickness of 500 nm. Its scanning electron microscope morphology is as follows. Figure 3A As shown.

[0048] Example 3 (PMMA / ethyl acetate and butyl acetate, lifting speed 360 mm / min): Example 3 provides a high permeability multilayer flexible soft magnetic film and its preparation method. The preparation method is largely the same as the preparation method of the high permeability multilayer flexible soft magnetic film provided in Example 1, except for step (4): Step (4) Preparation of polymer insulating dielectric layer: The electroplated PET substrate is immersed in a solution of polymethyl methacrylate (PMMA) / ethyl acetate and butyl acetate (mass ratio 1:1) with a mass fraction of 7.7 wt%, and the film is formed by wetting and pulling at a pulling speed of 360 mm / min. After film formation, it is dried for 10 min to obtain a polymer insulating dielectric layer with an average thickness of 500 nm.

[0049] Comparative Example 1 (using only electroplating process): Comparative Example 1 provides a method for preparing a magnetic thin film, the specific steps of which are as follows: Step (1) Selecting a substrate: Take a PET substrate with a thickness of 5μm as the substrate for preparing the magnetic film.

[0050] Step (2) Preparation of electroplating seed layer: Ni is deposited on the surface of PET substrate by magnetron sputtering. 80 Fe 20 The alloy was sputtered for approximately 6 minutes to form a 50 nm conductive seed layer.

[0051] Step (3) Electroplating to prepare the electroplated magnetic layer: First, the PET substrate with the deposited conductive seed layer is immersed in the electroplating solution, which consists of: 0.06 mol / L ferrous sulfate heptahydrate, 0.6 mol / L nickel sulfate hexahydrate, 0.06 mol / L nickel chloride, and 0.06 mol / L cobalt chloride; then, the pH of the electroplating solution is adjusted to 3.5, and the temperature of the electroplating solution is controlled at 30℃; finally, using the PET substrate as the cathode and the platinum electrode as the anode, 2A / dm² is applied. 2 A pulsed current density of 360 s was used to form an electroplated magnetic layer of Fe-Ni-Co alloy on the surface of the conductive seed layer. Finally, the electroplated magnetic layer and the conductive seed layer together constituted a magnetic thin film with a total thickness of 2 μm. The morphology of the resulting film is as follows: Figure 2 As shown in the figure on the right.

[0052] Comparative Example 2 (Non-dense silicon dioxide layer): Comparative Example 2 provides a method for preparing a multilayer magnetic thin film, the specific steps of which are as follows: Step (1) Selecting a substrate: Take a PET substrate with a thickness of 5 μm as the substrate for preparing multilayer magnetic films.

[0053] Step (2) Preparation of electroplating seed layer: Ni is deposited on the surface of PET substrate by magnetron sputtering. 80 Fe 20 The alloy was sputtered for approximately 6 minutes to form a 50 nm conductive seed layer.

[0054] Step (3) Electroplating to prepare the electroplated magnetic layer: First, the PET substrate with the deposited conductive seed layer is immersed in the electroplating solution, which consists of: 0.06 mol / L ferrous sulfate heptahydrate, 0.6 mol / L nickel sulfate hexahydrate, 0.06 mol / L nickel chloride, and 0.06 mol / L cobalt chloride; then, the pH of the electroplating solution is adjusted to 3.5, and the temperature of the electroplating solution is controlled at 30℃; finally, using the PET substrate as the cathode and the platinum electrode as the anode, 2A / dm² is applied. 2 With a pulsed current density and an electroplating time of 90s, a 450nm Fe-Ni-Co alloy electroplated magnetic layer was formed on the surface of the conductive seed layer.

[0055] Step (4) Preparation of non-dense silica layer: The electroplated PET substrate is immersed in a 7wt% tetraethyl orthosilicate / ethanol solution and pulled into a film at a pulling speed of 480mm / min. After film formation, it is dried for 10min to obtain a non-dense silica layer with an average thickness of 300nm.

[0056] Step (5) Cyclic operation to prepare multilayer magnetic thin film: Repeat the above steps (2), (3) and (4) multiple times, cycle 3 times to obtain multilayer magnetic thin film; wherein, the number of magnetic metal layers in the multilayer magnetic thin film is 4.

[0057] Comparative Example 2 uses a non-dense silica layer prepared by the Czochralski method, which has low density and high porosity. Four-probe resistance testing shows that the resistivity of this layer is close to that of the electroplated magnetic layer, and its conductivity is relatively high. Therefore, it cannot form an effective insulating barrier layer and cannot suppress high-frequency eddy current losses. Ultimately, its high-frequency permeability curve is basically consistent with that of Comparative Example 1, which did not introduce an insulating dielectric layer. Specifically, as shown below... Figure 4 As shown.

[0058] Comparative Example 3 (lifting speed 6mm / min): Comparative Example 3 provides a method for preparing a multilayer magnetic thin film, the specific steps of which are as follows: Step (1) Selecting a substrate: Take a PET substrate with a thickness of 5 μm as the substrate for preparing multilayer magnetic films.

[0059] Step (2) Preparation of electroplating seed layer: Ni is deposited on the surface of PET substrate by magnetron sputtering. 80 Fe 20 The alloy was sputtered for approximately 6 minutes to form a 50 nm conductive seed layer.

[0060] Step (3) Electroplating to prepare the electroplated magnetic layer: First, the PET substrate with the deposited conductive seed layer is immersed in the electroplating solution, which consists of: 0.06 mol / L ferrous sulfate heptahydrate, 0.6 mol / L nickel sulfate hexahydrate, 0.06 mol / L nickel chloride, and 0.06 mol / L cobalt chloride; then, the pH of the electroplating solution is adjusted to 3.5, and the temperature of the electroplating solution is controlled at 30℃; finally, using the PET substrate as the cathode and the platinum electrode as the anode, 2A / dm² is applied. 2 With a pulsed current density and an electroplating time of 90s, a 450nm Fe-Ni-Co alloy electroplated magnetic layer was formed on the surface of the conductive seed layer.

[0061] Step (4) Preparation of the polymer insulating dielectric layer: The electroplated PET substrate was immersed in a 5.2 wt% polyvinyl butyral (PVB, molecular weight 40,000-70,000) / ethanol solution, and the film was formed by wetting and pulling at a pulling speed of 6 mm / min. After film formation, it was dried for 10 min to obtain a polymer insulating dielectric layer with an average thickness of about 100 nm. Its scanning electron microscope morphology is as follows. Figure 3B As shown.

[0062] Step (5) Cyclic operation to prepare multilayer flexible soft magnetic film: Repeat the above steps (2), (3) and (4) multiple times, cycle 3 times, to obtain multilayer magnetic film; wherein, the number of magnetic metal layers in the multilayer magnetic film is 4.

[0063] The pulling speed used in Comparative Example 3 was too low, and the thickness of the polymer insulating dielectric layer was only 100 nm, resulting in limited insulation effect. The high-frequency magnetic permeability was slightly improved, as shown in the attached figure. Figure 4 As shown.

[0064] Comparative Example 4 (PMMA / ethyl acetate and butyl acetate + lifting speed of 240 mm / min): Comparative Example 4 provides a method for preparing a multilayer magnetic thin film, the specific steps of which are as follows: Step (1) Selecting a substrate: Take a PET substrate with a thickness of 5 μm as the substrate for preparing multilayer magnetic films.

[0065] Step (2) Preparation of electroplating seed layer: Ni is deposited on the surface of PET substrate by magnetron sputtering. 80 Fe 20 The alloy was sputtered for approximately 6 minutes to form a 30 nm conductive seed layer.

[0066] Step (3) Electroplating to prepare the electroplated magnetic layer: First, the PET substrate with the deposited conductive seed layer is immersed in the electroplating solution, which consists of: 0.06 mol / L ferrous sulfate heptahydrate, 0.6 mol / L nickel sulfate hexahydrate, 0.06 mol / L nickel chloride, and 0.06 mol / L cobalt chloride; then, the pH of the electroplating solution is adjusted to 3.5, and the temperature of the electroplating solution is controlled at 30℃; finally, using the PET substrate as the cathode and the platinum electrode as the anode, 2A / dm² is applied. 2 With a pulsed current density and an electroplating time of 90s, a 450nm Fe-Ni-Co alloy electroplated magnetic layer was formed on the surface of the conductive seed layer.

[0067] Step (4) Preparation of polymer insulating dielectric layer: The electroplated PET substrate is immersed in 7.7wt% polymethyl methacrylate (PMMA) / ethyl acetate and butyl acetate (mass ratio 1:1), and the film is formed by immersion and pulling at a pulling speed of 240mm / min. After film formation, it is dried for 10min to obtain a polymer insulating dielectric layer with an average thickness of about 300nm.

[0068] Step (5) Cyclic operation to prepare multilayer flexible soft magnetic film: Repeat the above steps (2), (3) and (4) multiple times, cycle 3 times, to obtain multilayer magnetic film.

[0069] Results and Analysis: Please see Figure 2 , Figure 2 The multilayer flexible soft magnetic film prepared in Example 1 ( Figure 2 (Left figure) and the magnetic thin film prepared in Comparative Example 1 ( Figure 2 The image on the right shows a comparison of the thickness measured by scanning electron microscopy. Figure 2 It can be seen that: Example 1, using an alternating cycle process of "electroplating to prepare a magnetic metal layer + dip-coating to prepare a PVB polymer insulating dielectric layer," produces a multilayer flexible soft magnetic film exhibiting a clear and complete layered stacked structure. The interfaces between each layer are distinct, without delamination or damage. The PVB polymer insulating layer has a uniform thickness (average approximately 300 nm), effectively isolating adjacent magnetic metal layers and achieving a multilayer structure with a high magnetic layer ratio. Comparative Example 1, without using the polymer dip-coating process, directly electroplated to a total thickness of 2 μm in a single step. The resulting film is a single thick magnetic layer structure with no delamination interfaces in the cross-section. Furthermore, due to the lack of an insulating layer to buffer stress, the overall film density is poor, exhibiting obvious interlayer cracking, film lifting, and peeling defects (such as...). Figure 2 The bulging and damaged morphology of the upper film layer in the right figure shows that a stable multilayer structure cannot be formed, further confirming the key role of the polymer pulling insulating layer process in improving the structural integrity and magnetic properties of the thin film.

[0070] Please refer to Figure 3. Figure 3 shows the imaginary part (μ'') of the permeability of the multilayer flexible soft magnetic films prepared in Examples 1-3 and the magnetic films prepared in Comparative Examples 1-3 in the full frequency band of 0-2.5 GHz. As can be seen from Figure 3, the imaginary part of the permeability of all samples decreases with increasing frequency. Among them, the imaginary part of the permeability of Examples 1-3 is significantly higher than that of Comparative Examples 1-3 in the full frequency band, and the peak value of the imaginary part of the permeability of the three (about 700-800) is much higher than that of the comparative examples. They maintain a higher magnetic loss level in the high frequency band of 0.1-2.5 GHz. Specifically, the imaginary part of the permeability of Example 2 is the best in the full frequency band, followed by Example 3. Example 1 is slightly lower than Example 2 but still significantly better than all comparative examples. Comparative Example 1, which did not use the Czochralski method to prepare the polymer insulating dielectric layer, is a single thick magnetic layer structure. Due to the eddy current effect, the imaginary part of the magnetic permeability decays rapidly after the low frequency band, resulting in a significant decrease in high-frequency magnetic loss capability. Comparative Example 2, which uses the tetraethyl orthosilicate Czochralski method to prepare a non-dense silica insulating layer, failed to achieve effective insulation barrier. Its imaginary part of magnetic permeability curve highly overlaps with that of Comparative Example 1, and there is no significant improvement in high-frequency magnetic performance. Comparative Example 3, which uses a PVB material polymer insulating dielectric layer with a thickness of less than 100 nm prepared with an excessively low Czochralski speed, has limited interlayer isolation effect. Its imaginary part of magnetic permeability is only slightly higher than that of Comparative Examples 1 and 2, and far lower than that of Examples 1 to 3 of this invention.

[0071] Furthermore, the real part, imaginary part, and magnetic layer occupancy of the permeability at 1 GHz for Examples 1-3 and Comparative Examples 1-3 are shown in Table 1: Table 1

[0072] As shown in Table 1, under 1GHz test conditions, the imaginary part of the permeability of Examples 1-3 is significantly higher than that of Comparative Examples 1-3, with Example 2 having the highest imaginary part of permeability. Although the proportion of magnetic layers in Examples 1-3 is much lower than that in Comparative Example 1 (100%), the introduction of a polymer insulating layer with controllable thickness effectively suppresses the eddy current effect and optimizes interlayer coupling. While significantly reducing the amount of magnetic material used, it achieves a significant improvement in high-frequency magnetic loss performance, fully verifying the superiority of the multilayer structure design and process parameters of this invention.

[0073] Please see Figure 5 , Figure 5 This is a photograph of the damaged polymer insulating dielectric layer in the multilayer magnetic thin film provided in Comparative Example 4; by Figure 5As can be seen, the surface of the multilayer magnetic thin film prepared in Comparative Example 4 showed severe damage and cracking, with obvious film peeling, wrinkles, and fragmentation in local areas. This is because the pull-up speed of the PMMA insulating layer in Comparative Example 4 was set too low, resulting in a thin insulating layer with insufficient mechanical strength. During the cyclic magnetron sputtering and electroplating process, the internal stress generated by the process continuously accumulated and was transmitted to the fragile PMMA dielectric layer. When the stress reached the withstand limit of the fourth insulating layer, the insulating layer cracked or even fell off, thereby destroying the overall structural integrity of the multilayer thin film. This directly demonstrates the necessity of the present invention to optimize the insulating layer thickness and ensure the stability of the interlayer structure by controlling the pull-up speed.

[0074] Specifically, the core innovation of Examples 1-3, which employ electroplating combined with polymer lamination to suppress eddy current losses and improve high-frequency permeability, lies in the design and realization of a rapidly and cost-effective method for fabricating a multilayer thin film structure with controllable thickness of alternating metal / insulating dielectric materials. This technology is not a simple superposition of two processes, but rather, through their synergistic effect, it decouples and reconstructs the magnetic flux path and current path of the material at the micro-nano scale, fundamentally breaking through the physical bottleneck of traditional soft magnetic materials in high-frequency applications. Its core mechanism is as follows: First, the electrodeposition process constructs a continuous Fe-Ni-Co magnetic metallic phase with high saturation magnetization and low coercivity, providing an intrinsic magnetic basis for the high permeability of the thin film. However, thick metal conductors are prone to forming large-scale eddy current loops under alternating magnetic fields, leading to severe skin effect and eddy current loss, resulting in a sharp decay of high-frequency magnetic properties. The subsequent polymer pulling process (such as wetting and pulling polymer solutions such as PVB and PMMA) plays a crucial role in dielectric phase control: the polymer precursor solution fully penetrates and covers the surface and micro-defects of the electroplated layer, forming a continuous, dense insulating dielectric layer with nanometer-scale thickness after solvent evaporation. By precisely controlling process parameters such as the pulling speed, the thickness of the dielectric layer can be stably controlled within the target range, maximizing the magnetic layer ratio while ensuring insulation effect, and further improving magnetic loss efficiency.

[0075] This insulating layer constructs a distributed high-resistance network in three-dimensional space. Its core innovative value lies in physically blocking the transverse eddy current paths within and between layers, dividing the originally macroscopically continuous conductor into numerous microscopic magnetic units surrounded by insulating boundaries. Under high-frequency magnetic field excitation, eddy currents are strictly confined within each microscopic unit, significantly reducing the effective flow cross-sectional area and significantly increasing the loop resistance, thus directly suppressing eddy current losses from a physical perspective. At the same time, the magnetic exchange coupling between magnetic units is not completely severed, and the overall soft magnetic properties of the material are fully preserved. This microscopic heterostructure of "magnetic flux conduction, current isolation" enables the composite film to maintain a high real permeability while significantly increasing the imaginary permeability, achieving synergistic optimization of intrinsic magnetic properties and macroscopic electromagnetic performance.

[0076] In summary, this invention essentially solves the high-frequency eddy current bottleneck of soft magnetic materials in a single material system through nanoscale heterogeneous interface engineering, providing a novel material and process solution for high-performance high-frequency integrated magnetic devices. Compared with existing technologies, the beneficial effects of this invention include: (1) High efficiency and low cost: The use of electroplating and polymer pulling process to quickly prepare thick magnetic layer and insulating dielectric layer significantly improves preparation efficiency and reduces production cost, making it suitable for large-scale production.

[0077] (2) High magnetic layer ratio: By controlling the polymer insulation layer thickness between 100 and 500 nm through polymer concentration, solvent selection and wetting and pulling speed, the volume ratio of non-magnetic layer is minimized, thereby improving the overall magnetic properties.

[0078] (3) Excellent eddy current suppression: The thin and continuous polymer insulating dielectric layer effectively blocks the interlayer eddy current path and reduces high-frequency eddy current loss.

[0079] (4) Good mechanical properties and flexibility: The polymer insulating layer can effectively absorb and release stress. It will not crack due to stress during the magnetron seed layer and electroplating process, and prevents the multilayer structure from cracking under bending or thermal shock, making it suitable for applications in the field of flexible electronics.

[0080] (5) Improve the magnetic properties of the thin film: the thickness of the magnetic layer reaches 30-80%, and the peak value of the effective magnetic permeability can reach 600-800. The imaginary part of the magnetic permeability of the multilayer thin film prepared by the Czochralski process is increased by about 2 times at 1 GHz, providing a new solution for the preparation of electroplated multilayer thin films.

[0081] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0082] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A multilayer flexible soft magnetic thin film with high magnetic permeability, characterized in that, It includes at least two magnetic metal layers and at least one polymer insulating dielectric layer that are alternately stacked, and each of the polymer insulating dielectric layers is sandwiched between two adjacent magnetic metal layers; The thickness of each magnetic metal layer is 200–900 nm, the thickness of each polymer insulating dielectric layer is 100–500 nm, and the total thickness of the multiple magnetic metal layers accounts for 30%–80% of the thickness of the multilayer flexible soft magnetic film; the peak value of the imaginary part of the effective magnetic permeability of the multilayer flexible soft magnetic film is greater than 400.

2. The multilayer flexible soft magnetic film according to claim 1, characterized in that, The number of magnetic metal layers in the multilayer flexible soft magnetic film is 2 to 20.

3. The multilayer flexible soft magnetic film according to claim 2, characterized in that, The magnetic metal layer includes a conductive seed layer and an electroplated magnetic layer stacked from bottom to top; the conductive seed layer is a conductive metal or an organic conductive polymer, wherein the conductive metal is selected from at least one of iron, nickel, iron-nickel alloy, copper or molybdenum, and the organic conductive polymer is selected from polypyrrole or polyaniline; the electroplated magnetic layer is selected from at least one of iron, nickel, cobalt, iron-nickel alloy, iron-cobalt alloy or iron-nickel-cobalt alloy.

4. The multilayer flexible soft magnetic film according to claim 2, characterized in that, The polymer insulating dielectric layer is a flexible polymer layer prepared by dip-coating method, and its material is selected from polyvinyl butyral or polymethyl methacrylate.

5. A method for preparing a multilayer flexible soft magnetic thin film with high magnetic permeability, characterized in that, The method includes the following steps: S10, a conductive seed layer is prepared on a substrate, and an electroplated magnetic layer is deposited on the conductive seed layer by electroplating to obtain a magnetic metal layer with a thickness of 200-900 nm. S20, the obtained structure is immersed in a flexible polymer solution, and a polymer insulating dielectric layer with a thickness of 100-500 nm is formed by dip-coating method; S30, repeat steps S10 to S20 to obtain a multilayer flexible soft magnetic film with alternating layers of magnetic metal layer and polymer insulating dielectric layer; Each of the polymer insulating dielectric layers is sandwiched between two adjacent magnetic metal layers, and the total thickness of the magnetic metal layers accounts for 30-80% of the total thickness of the multilayer flexible soft magnetic film; the peak value of the imaginary part of the effective magnetic permeability of the multilayer flexible soft magnetic film is greater than 400.

6. The method for preparing a multilayer flexible soft magnetic thin film according to claim 5, characterized in that, In step S10, the method for preparing the conductive seed layer is selected from one of magnetron sputtering, chemical vapor deposition, atomic layer deposition, or electroless plating.

7. The method for preparing a multilayer flexible soft magnetic thin film according to claim 6, characterized in that, In step S10, the conductive seed layer is prepared by magnetron sputtering on the substrate for 3–15 min; the electroplated magnetic layer is an iron-nickel-cobalt alloy, and the process conditions for depositing the electroplated magnetic layer are: pH value of the electroplating solution 2–5, electroplating temperature 20–50℃, and pulse current density 1–2 A / dm³. 2 .

8. The method for preparing a multilayer flexible soft magnetic thin film according to claim 5, characterized in that, In step S20, the flexible polymer solution is prepared by mixing a flexible polymer with an organic solvent at a mass fraction of 5-20 wt%, and the lifting speed of the immersion lifting method is 10-480 mm / min. The flexible polymer is polyvinyl butyral or polymethyl methacrylate, and the organic solvent is selected from at least one of ethanol, ethyl acetate, and butyl acetate.

9. The method for preparing a multilayer flexible soft magnetic thin film according to claim 5, characterized in that, In step S30, the number of magnetic metal layers in the multilayer flexible soft magnetic film is 2 to 20.

10. An application of a multilayer flexible soft magnetic thin film as described in any one of claims 1 to 4, characterized in that, The multilayer flexible soft magnetic film is applied in the field of high-frequency electronic devices or the field of 5G communication electromagnetic compatibility. The high-frequency electronic devices include at least one of microwave filters, noise suppression sheets, and flexible sensors.

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