A magnetic dielectric metal-clad laminate and a method of manufacturing and use thereof

Abstract

This invention provides a magnetic dielectric metal foil laminate, its preparation method, and its applications. The preparation method includes: providing a magnetic dielectric sheet; the magnetic dielectric sheet comprising at least one prepreg, the prepreg comprising a reinforcing material and a magnetic dielectric resin composition attached to the reinforcing material; the magnetic dielectric resin composition comprising a combination of resin and anisotropic magnetic filler; laminating a metal foil onto one or both sides of the magnetic dielectric sheet to obtain a composite; hot-pressing the composite to obtain the magnetic dielectric metal foil laminate; and applying a magnetic field during the hot-pressing process. This invention uses a magnetic dielectric sheet containing anisotropic magnetic filler and applies a magnetic field using a specific method during the hot-pressing process, resulting in a magnetic dielectric metal foil laminate with significantly improved permeability and dielectric constant, low magnetic loss and dielectric loss, and excellent magnetic dielectric performance and reliability, thereby improving impedance matching, miniaturization factor, and antenna bandwidth.

Description

Technical Field

[0001] This invention belongs to the field of circuit board technology, specifically relating to a magnetic dielectric metal foil laminate, its preparation method, and its application. Background Technology

[0002] With the continuous development of science and technology, there is an urgent need for high-performance, miniaturized, and electromagnetic interference-resistant high-frequency magnetic materials in electronic information technology, especially in the field of communication antennas, where bandwidth, gain, and small size are of particular concern. Traditional antennas only have certain dielectric functions. With the needs of technological development, high dielectric products can also achieve a certain degree of miniaturization. In recent years, magnetic dielectrics have been proposed to further optimize antenna performance.

[0003] Using a magnetic dielectric material as the substrate, the electromagnetic parameters of the magnetic dielectric material influence the antenna size, primarily through its high refractive index. Miniaturization of antennas is achieved by using materials with a high miniaturization factor as the antenna substrate. Key parameters include relative permeability and relative permittivity. While high permittivity materials are commonly chosen in the industry, this approach results in narrow antenna bandwidth, low gain, and design difficulties. Using a magnetic-dielectric material that possesses both magnetic and dielectric properties is an effective method for reducing antenna size with minimal impact on other antenna performance characteristics. The specific formula is as follows: Where λ, c, f, BW, Zm, and Z0 represent the electromagnetic wave wavelength, light speed, antenna resonant frequency, antenna bandwidth, substrate material impedance, and free-space impedance of the substrate material, respectively. According to the aforementioned formula, the larger the miniaturization factor n, the smaller the size can be. An increase in the dielectric constant εr leads to a decrease in bandwidth BW, and simultaneously a decrease in impedance. This makes impedance matching between the antenna and the feed end difficult. In other words, materials with high dielectric constants increase the confinement of electromagnetic waves within the dielectric region, further narrowing the antenna's operating bandwidth, reducing gain, and making design difficult. However, increasing the permeability can effectively reduce the antenna size while maintaining the antenna's gain and bandwidth.

[0004] Currently, the industry is attempting to diversify the permeability and dielectric constant through substrate design to meet the performance requirements of dielectric materials in miniaturized antenna applications. For example, CN109553955A discloses a magnetic dielectric resin composition and prepreg, laminate, and copper-clad laminate containing the composition. This composition comprises 30-100 parts by weight of resin and 50-500 parts by weight of magnetic filler. The magnetic filler has a resistivity of 100 Ω·M-1000 Ω·M and a permeability of 5-1000, giving the copper-clad laminate containing it good magnetic properties and insulation. CN106797699A discloses a magnetic dielectric substrate, circuit material, and components. This substrate includes a first dielectric layer and a second dielectric layer, and at least one magnetic reinforcement layer disposed between and in close contact with the two dielectric layers. The magnetic reinforcement layer contains ferrite material, thereby giving the substrate good mechanical and magnetoelectronic properties. CN104910823A discloses an adhesive film capable of forming an insulating layer, comprising a support and a resin composition layer disposed on the support. The resin composition layer contains a thermosetting resin, a magnetic filler, and an inorganic filler material, wherein the content of the magnetic filler is ≥10% by volume, and the ratio of the content of the magnetic filler to the inorganic filler material is 0.3-3.0, thereby increasing the magnetic permeability of the insulating layer and reducing magnetic loss.

[0005] With the advancement of antenna miniaturization, existing magnetic dielectric materials have significant shortcomings in simultaneously improving both dielectric constant and permeability. They struggle to achieve a balance between increasing both, resulting in poor impedance matching, narrow antenna bandwidth, low gain, and insufficient miniaturization factor. Furthermore, improving dielectric constant and permeability is accompanied by increased magnetic loss, increased dielectric loss, and decreased reliability, severely limiting the application of magnetic dielectric materials in antennas, communication equipment, and electronic products. Therefore, developing a magnetic dielectric material with high permeability and dielectric constant, low magnetic loss and dielectric loss, and achieving a high miniaturization factor and antenna bandwidth is a pressing issue in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a magnetic dielectric metal foil laminate, its preparation method, and its applications. By employing a magnetic dielectric material containing anisotropic magnetic fillers and applying a magnetic field using a specific method during hot pressing, the resulting magnetic dielectric metal foil laminate exhibits significantly improved permeability and dielectric constant, as well as low magnetic and dielectric losses, excellent magnetic dielectric performance, and high reliability. This improves impedance matching, enhances miniaturization factor and antenna bandwidth, and meets the performance requirements of miniaturized antennas.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a magnetically dielectric metal foil laminate, the method comprising:

[0009] A magnetic dielectric sheet is provided; the magnetic dielectric sheet comprises at least one prepreg, the prepreg comprising a reinforcing material and a magnetic dielectric resin composition attached to the reinforcing material; the magnetic dielectric resin composition comprises a combination of resin and anisotropic magnetic filler;

[0010] A composite material is obtained by laminating a metal foil onto one or both sides of the magnetic dielectric substrate;

[0011] The composite is hot-pressed to obtain the magnetic dielectric metal foil laminate;

[0012] A magnetic field is applied during the hot pressing process, and the method of applying the magnetic field includes any one of method A, method B or method C;

[0013] Method A includes: placing the composite in a non-magnetic mold located in a first magnetic field, wherein the non-magnetic mold rotates in the first magnetic field;

[0014] Method B includes: placing the composite between a magnet and a rotating magnet, wherein a second magnetic field is formed between the magnet and the rotating magnet;

[0015] Method C includes: placing the composite material in a third magnetic field, wherein the device generating the third magnetic field includes n groups of magnets with coincident center points, where n is an integer ≥2; each group of magnets is independently composed of a first magnet and a second magnet, wherein the N pole of the first magnet and the S pole of the second magnet in each group of magnets are arranged opposite each other, and a third magnetic field is formed between the N pole and the S pole; the included angle between any two adjacent groups of magnets is equal.

[0016] To improve the permeability and dielectric constant of magnetic dielectric metal-coated foil laminates and reduce their magnetic and dielectric losses, this invention provides a method for preparing magnetic dielectric metal-coated foil laminates with an applied magnetic field. This method utilizes a magnetic dielectric material containing anisotropic magnetic fillers and applies a magnetic field during hot pressing using a specific method. The anisotropic magnetic fillers (orientable magnetic fillers) are oriented under the influence of the magnetic field. Under the combined effects of temperature, pressure, and magnetic field during hot pressing, the anisotropic magnetic fillers in the magnetic dielectric material form a specific "leaf-like" structure, resulting in a more orderly and higher-oriented grain arrangement of the anisotropic magnetic fillers. This significantly improves the permeability and dielectric constant of the resulting magnetic dielectric metal-coated foil laminate, while also exhibiting low magnetic and dielectric losses, excellent heat resistance, and reliability. This invention solves the problems of low permeability, poor impedance matching, insufficient miniaturization factor, narrow antenna bandwidth, low gain, and design difficulties of existing magnetic dielectric materials by coupling the magnetic field, temperature, and pressure of hot pressing. It obtains a magnetic dielectric metal foil laminate with high permeability, high dielectric constant, low magnetic loss, low dielectric loss, and high reliability, which fully meets the performance requirements of the substrate in miniaturized antennas.

[0017] In this invention, there are three methods for applying a magnetic field, as detailed below:

[0018] In Method A, the hot-pressed composite is placed in a non-magnetic mold, and the non-magnetic mold is rotated in the first magnetic field. That is, the composite to be hot-pressed rotates in the first magnetic field, so that the anisotropic magnetic filler in the composite is actually subjected to the rotating magnetic field (the first magnetic field is relatively stationary, and the sample rotates, resulting in the sample being actually subjected to the rotating magnetic field). Under the coupled synergistic effect of the magnetic field, the temperature and pressure of hot pressing, the anisotropic magnetic filler is oriented and forms a specific high-orientation structure.

[0019] In Method B, a second dynamic magnetic field is formed between the magnetic particle and the rotating magnet. Specifically, the magnetic particle rotates under the coupling drive of the rotating magnet, and a dynamic second magnetic field is formed between the rotating magnet and the rotating magnetic particle. The composite to be hot-pressed is placed in a hot-pressing device and positioned within the dynamic second magnetic field (between the rotating magnet and the rotating magnetic particle), thereby applying the dynamic magnetic field during the hot-pressing process. The sample in this method remains relatively stationary, and the second magnetic field has dynamic characteristics. The temperature, pressure, and dynamic magnetic field of the hot-pressing process are coupled together, causing the anisotropic magnetic filler to form a specific high-orientation structure.

[0020] In method C, the third magnetic field is generated by n (n≥2) magnet groups with coincident center points. Each magnet group consists of a first magnet and a second magnet, with the N pole of the first magnet and the S pole of the second magnet positioned opposite each other, thus forming a magnetic field between the N and S poles. Since a magnetic field (which can be understood as a "sub-magnetic field") is formed between the N pole of the first magnet and the S pole of the second magnet in each magnet group, the center points of the n "sub-magnetic fields" also coincide. The n sub-magnetic fields couple with each other and form a third magnetic field with dynamic rotational characteristics based on the characteristics of magnetic field lines. The hot-pressed composite is located in the third magnetic field, causing the anisotropic magnetic filler in the composite to align in a specific high-orientation structure under the coupled synergistic effect of the magnetic field, the temperature, and the pressure of hot pressing.

[0021] Therefore, in the preparation method provided by the present invention, a magnetic field is applied during the hot pressing process using three different methods, so that the anisotropic magnetic filler in the composite is oriented and arranged under the coupled synergistic effect of a specific magnetic field, hot pressing temperature and pressure, forming a specific high orientation structure. This endows the magnetic dielectric metal foil laminate with high permeability, high dielectric constant, low magnetic loss and low dielectric loss performance characteristics, thereby improving impedance matching, enhancing miniaturization factor, antenna bandwidth and gain, and fully meeting the performance requirements of the substrate in miniaturized antennas.

[0022] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0023] Preferably, the anisotropic magnetic filler includes any one or a combination of at least two of planar hexagonal ferrite, magnetoplumbago ferrite, and other soft magnetic ferrites.

[0024] Preferably, the planar hexagonal ferrite includes any one or a combination of at least two of the following: Y-type planar hexagonal ferrite, Co2Z-type planar hexagonal ferrite, and Co2W-type planar hexagonal ferrite.

[0025] Preferably, the median particle size of the anisotropic magnetic filler is 0.1-30 μm, for example, it can be 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm or 28 μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 1-15 μm is further preferred.

[0026] For example, the particle size of the anisotropic magnetic filler was obtained by testing with an MS3000 Malvern laser particle size analyzer.

[0027] Preferably, the mass percentage of anisotropic magnetic filler in the magnetic dielectric resin composition is 10%-80%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] Preferably, the resin comprises any one or a combination of at least two of epoxy resin, phenolic resin, cyanate ester resin, polyphenylene ether resin, polyolefin resin, styrene-butadiene resin, maleimide compound, phenolic resin, fluorinated resin, and benzoxazine resin.

[0029] Preferably, the epoxy resin comprises any one or a combination of at least two of the following: bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, dicyclopentadiene (DCPD) type epoxy resin, phenolic epoxy resin, biphenyl type epoxy resin, phenolic epoxy resin, bisphenol A phenolic epoxy resin, organosilicon modified epoxy resin, phosphorus-containing epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, and o-cresol epoxy resin.

[0030] Preferably, the polyphenylene ether resin is an unsaturated polyphenylene ether, and more preferably, it is a polyphenylene ether with unsaturated groups at the end; wherein the unsaturated groups can be any one or a combination of at least two of vinyl, vinyl benzyl, vinyl phenyl, acrylate, and methacrylate groups.

[0031] Preferably, the polyolefin resin includes polybutadiene.

[0032] Preferably, the polybutadiene contains butadiene 1,2-polymer structural units.

[0033] Preferably, the maleimide compound comprises a bismaleimide resin.

[0034] Preferably, the styrene-butadiene resin is a butadiene-styrene copolymer, specifically a butadiene-styrene random copolymer and / or a butadiene-styrene block copolymer.

[0035] Preferably, the magnetic dielectric resin composition further includes any one or a combination of at least two of the following: curing agent, accelerator, crosslinking agent, initiator, flame retardant, coupling agent, and non-magnetic filler.

[0036] Preferably, the resin includes epoxy resin, and the curing agent includes any one or a combination of at least two of phenolic resin, amine curing agent, cyanate ester curing agent, reactive ester curing agent, carboxylic acid curing agent, and acid anhydride curing agent.

[0037] Preferably, the accelerator comprises any one or a combination of at least two of imidazole compounds, organometallic complexes, tertiary amines, tertiary phosphine, quaternary ammonium salts, and peroxides.

[0038] Preferably, the imidazole compound includes any one or a combination of at least two of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2-phenyl-4-methylimidazole, 2-dodecylimidazole, and 1-cyanoethyl-2-methylimidazole.

[0039] Preferably, the peroxide comprises any one or a combination of at least two of the following: dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyn-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and α,α'-bis(tert-butylperoxy)dicumyl peroxide.

[0040] In a preferred embodiment, the magnetic dielectric resin composition comprises the following components in parts by weight:

[0041]

[0042] Specifically, the unsaturated polyphenylene ether is 10-50 parts, for example, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts or 45 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0043] The polybutadiene and / or styrene-butadiene copolymer is 20-80 parts, for example, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts or 75 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0044] The bismaleimide resin is 5-30 parts, for example, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts or 28 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0045] The anisotropic magnetic filler is 10-400 parts, for example, it can be 20 parts, 50 parts, 80 parts, 100 parts, 120 parts, 150 parts, 180 parts, 200 parts, 220 parts, 250 parts, 280 parts, 300 parts, 320 parts, 350 parts, 380 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0046] The accelerator is 0.01-2 parts, for example, it can be 0.01 parts, 0.03 parts, 0.05 parts, 0.07 parts, 0.09 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1 part, 1.2 parts, 1.5 parts or 1.8 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0047] Preferably, there is no particular limitation on the type of flame retardant. Flame retardants with flame retardant effect can be used in the magnetic dielectric resin composition, including but not limited to: any one or a combination of at least two of the following: inorganic flame retardants, phosphorus-based organic flame retardants, nitrogen-based organic flame retardants, silicon-containing organic flame retardants, and halogen-containing flame retardants (e.g., chlorine-containing flame retardants and / or bromine-containing flame retardants).

[0048] Preferably, the coupling agent includes any one or a combination of at least two of silane coupling agents, titanate coupling agents, and organosilicon oligomers; the coupling agent helps to improve the compatibility between the anisotropic magnetic filler and the resin.

[0049] Solvents may also be added to the magnetic dielectric resin composition. The amount of solvent added is selected by those skilled in the art based on experience and process requirements, so that the magnetic dielectric resin composition reaches a suitable viscosity for use, facilitating impregnation, coating, and other processes. Subsequently, during drying, semi-curing, or complete curing stages, the solvent in the magnetic dielectric resin composition will partially or completely evaporate.

[0050] The type of solvent is not particularly limited, but can generally be ketones such as acetone, butanone, and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; alcohols such as methanol, ethanol, or butanol; alcohols such as ethyl cellosolve, butyl cellosolve, ethylene glycol monomethyl ether, carbitol, or butyl carbitol; and nitrogen-containing solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, or N-methyl-2-pyrrolidone. The solvent can be used alone or in mixtures of two or more. Ketones such as butanone, acetone, and cyclohexanone, and aromatic hydrocarbons such as toluene and xylene are preferred.

[0051] Preferably, the number of prepreg sheets in the magnetic dielectric sheet is 1-20, for example, 2, 3, 5, 7, 9, 10, 11, 13, 15, 17 or 19, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0052] Preferably, the magnetic dielectric resin composition is attached to the reinforcing material after impregnation and drying to obtain a prepreg.

[0053] Preferably, the method for preparing the prepreg includes: impregnating a reinforcing material with a solution of the magnetic dielectric resin composition, and then drying it to obtain the prepreg.

[0054] Preferably, the drying temperature is 80-180℃, for example 90℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃ or 175℃, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0055] Preferably, the drying time is 1-30 min, for example, it can be 2 min, 5 min, 8 min, 10 min, 15 min, 20 min or 25 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0056] Preferably, the reinforcing material includes any one of glass fiber cloth, non-woven fabric, quartz cloth, quartz glass fiber blended fabric, fiber paper, or wood pulp paper;

[0057] Preferably, the metal foil includes any one or a combination of at least two of copper foil, aluminum foil, nickel foil, and alloy foil.

[0058] Preferably, the metal foil is copper foil, and the magnetic dielectric metal foil laminate is a magnetic dielectric copper clad laminate.

[0059] Preferably, in method A, the composite is placed in a non-magnetic mold located in a first magnetic field and rotated under the electric power of a motor.

[0060] Preferably, the material of the non-magnetic mold includes any one or a combination of at least two of the following: magnetic shielding material, copper material, aluminum material, polymer (plastic) material, and stainless steel material.

[0061] Optionally, the non-magnetic mold in method A can be understood as a component located in the hot pressing device. The composite is placed in the non-magnetic mold and is subjected to the temperature and pressure of hot pressing on one hand, and the action of the first magnetic field on the other. All components of this hot pressing device are made of non-magnetic materials, so that only the anisotropic magnetic filler in the magnetic dielectric sheet responds to the magnetic field. This avoids interference between the hot pressing device and the interaction between the magnetic field and the anisotropic magnetic filler, which would affect the improvement of the magnetic permeability and dielectric constant of the magnetic dielectric metal foil laminate.

[0062] Preferably, in method A, the rotation speed of the non-magnetic mold is 1-100 r / min, for example, it can be 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min or 90 r / min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0063] As a preferred embodiment of the present invention, the non-magnetic mold (composite) rotates under the drive of a motor at a speed of 1-100 r / min. The composite rotates in a relatively static first magnetic field, thereby subjecting the anisotropic magnetic filler therein to a magnetic field with dynamic characteristics. This effect is coupled with the temperature and pressure of hot pressing, promoting the directional alignment of the anisotropic magnetic filler. If the rotation speed of the non-magnetic mold (composite) is too low, the anisotropic magnetic filler cannot be subjected to a magnetic field with suitable dynamic characteristics, thus making it difficult to promote the directional alignment of the anisotropic magnetic filler. If the rotation speed is too high, the anisotropic magnetic filler will have completed a new revolution before it can move effectively at high speeds, and the anisotropic magnetic filler will not achieve effective directional alignment, thus failing to improve the permeability and dielectric constant of the magnetic dielectric metal foil laminate.

[0064] Preferably, the field strength of the first magnetic field is 1-50 mT, for example, it can be 2 mT, 5 mT, 8 mT, 10 mT, 12 mT, 15 mT, 18 mT, 20 mT, 22 mT, 25 mT, 28 mT, 30 mT, 35 mT, 40 mT or 45 mT, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 3-30 mT is further preferred.

[0065] As a preferred technical solution of the present invention, in method A, there is no special limitation on the type of magnet and the surface field strength of the magnet that generates the first magnetic field, as long as it can generate a first magnetic field of 1-30mT and provide a magnetic field effect for the composite.

[0066] In method A of this invention, the field strength of the first magnetic field is the field strength of the magnetic field acting on / applied to the hot-pressed composite. The "field strength" is combined with the "rotation (dynamic) of the sample" and coupled with the temperature and pressure effects of hot pressing, causing the anisotropic magnetic filler in the magnetic dielectric substrate to oriented and form a neat and orderly specific leaf-like structure in the metal foil laminate. This structure exhibits high orientation and, without increasing the amount of anisotropic magnetic filler, imparts higher permeability and dielectric constant to the substrate. Simultaneously, it exhibits low magnetic loss and dielectric loss, resulting in excellent overall performance, including reliability. If the magnitude of the field strength or the rotation speed exceeds the preferred range of this invention, it will affect the oriented arrangement of the anisotropic magnetic filler, leading to a less significant increase in the permeability and dielectric constant of the substrate.

[0067] In method B of the present invention, the composite to be hot-pressed is placed in a hot-pressing device and located in a dynamic second magnetic field (between a rotating magnet and a rotating magnetic particle). This applies a dynamic magnetic field during the hot-pressing process, coupling the effects of temperature, pressure, and the dynamic magnetic field. It should be noted that the hot-pressing device is a non-magnetic product; that is, the materials of each component in the hot-pressing device are non-magnetic. Only the anisotropic magnetic filler in the magnetic dielectric sheet is responsive to the magnetic field, thus avoiding interference between the hot-pressing device and the interaction between the dynamic magnetic field and the anisotropic magnetic filler, which would otherwise affect the improvement of the permeability of the metal-clad laminate.

[0068] In this invention, the magnetic particle used to form the second magnetic field can be understood as a magnetic stirrer, which rotates under the coupling drive of the magnetic field provided by the rotating magnet, and together with the rotating magnet, constructs a dynamic second magnetic field. Any magnetic particle (magnetic stirrer) capable of rotating under the drive of a rotating magnet and forming a dynamic magnetic field can be used in method B of this invention.

[0069] Preferably, the shape of the magnetic particle includes cylindrical (C-type), olive-shaped (A-type), cylindrical with segmented shape (B-type), elliptical (C-type), X-shaped (C-type), spindle-shaped (C-type), or circular (C-type).

[0070] Preferably, in method B, the length of the magnet is 5-50mm, for example, it can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm or 45mm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0071] Preferably, in method B, the diameter of the magnet is 1-20mm, for example, it can be 3mm, 5mm, 8mm, 10mm, 12mm, 15mm, 16mm or 18mm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0072] Preferably, in method B, the surface field strength of the magnet is 10-100 mT, for example, it can be 20 mT, 30 mT, 40 mT, 50 mT, 60 mT, 70 mT, 80 mT or 90 mT, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0073] Preferably, in method B, the magnet rotates under the drive of a motor.

[0074] Preferably, in method B, the rotational speed of the magnet is 1-2500 r / min, for example, it can be 10 r / min, 30 r / min, 50 r / min, 80 r / min, 100 r / min, 300 r / min, 500 r / min, 800 r / min, 1000 r / min, 1200 r / min, 1500 r / min, 1800 r / min, 2000 r / min, 2200 r / min or 2400 r / min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0075] As a preferred embodiment of the present invention, in method B, the magnet rotates under the drive of a motor, and the rotation speed driven by the electrodes is 1-2500 r / min, more preferably 100-2500 r / min, thereby effectively driving the rotation of the magnet and forming a suitable second magnetic field with dynamic characteristics between the magnet and the magnet. If the rotation speed is too low, the magnet cannot be effectively driven to rotate, and a suitable second magnetic field cannot be formed; if the rotation speed is too high, a new revolution will have already passed before the anisotropic magnetic filler in the magnetic field formed by the high rotation speed has moved effectively, and the orientation effect of the anisotropic magnetic filler will be insignificant or impossible.

[0076] In method B of the present invention, the field strength of the magnet is not specifically limited, as long as it can drive the magnet to rotate and together with the magnet to construct a dynamic second magnetic field.

[0077] Preferably, in method B, the field strength of the second magnetic field is 0.1-20 mT, for example, it can be 0.5 mT, 1 mT, 2 mT, 3 mT, 4 mT, 5 mT, 6 mT, 8 mT, 10 mT, 12 mT, 15 mT or 18 mT, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0078] Optionally, in method C, the composite to be hot-pressed is placed in a hot-pressing apparatus and located in a third magnetic field. All components of the hot-pressing apparatus are made of non-magnetic materials. Only the anisotropic magnetic filler in the magnetic dielectric substrate is responsive to the magnetic field in the third magnetic field. This avoids interference between the hot-pressing apparatus and the interaction between the magnetic field and the anisotropic magnetic filler, thus preventing any impact on the permeability and dielectric constant of the magnetic dielectric metal foil laminate.

[0079] Preferably, in method C, the number n of magnet groups in the third magnetic field generating device can be 2, 3, 4, 5, 6, 7 or 8, more preferably 2-4, and even more preferably 2 or 3.

[0080] Preferably, in method C, the surface field strength of the first magnet and the second magnet are each independently 0.1mT-1T, for example, 0.2mT, 0.5mT, 0.8mT, 1mT, 5mT, 8mT, 10mT, 30mT, 50mT, 80mT, 100mT, 200mT, 300mT, 400mT, 500mT, 600mT, 700mT, 800mT, or 900mT, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0081] The distance between the first magnet and the second magnet in each magnet group is adjustable. Preferably, the distance between the N pole of the first magnet and the S pole of the second magnet in each magnet group is ≥1cm, for example, it can be 2cm, 5cm, 10cm, 15cm, 20cm, 25cm, 30cm, 35cm, 40cm, 45cm, 50cm, 55cm, 60cm, 65cm, 70cm, 80cm, 90cm or 100cm, as well as specific point values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range, and 2-60cm is further preferred.

[0082] Preferably, the field strength of the third magnetic field is 0.1-50 mT, for example, it can be 0.5 mT, 1 mT, 3 mT, 5 mT, 8 mT, 10 mT, 12 mT, 15 mT, 18 mT, 20 mT, 22 mT, 25 mT, 28 mT, 30 mT, 32 mT, 35 mT, 38 mT, 40 mT, 42 mT, 45 mT or 48 mT, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 5-30 mT is further preferred.

[0083] In method C of this invention, the field strength of the third magnetic field is the field strength of the magnetic field acting on / applied to the hot-pressed composite. The sub-magnetic fields generated by the n magnet groups work together to form a rotating magnetic field with a specific field strength, which couples with the temperature and pressure of the hot pressing, causing the anisotropic magnetic fillers in the magnetic dielectric sheet to be oriented. This forms a highly oriented specific structure in the magnetic dielectric metal-coated laminate. With a fixed amount of anisotropic magnetic fillers, the magnetic dielectric metal-coated laminate is endowed with higher permeability and dielectric constant, while having low magnetic loss and dielectric loss, resulting in excellent overall performance. If the field strength of the magnetic field is too low, the force on the anisotropic magnetic fillers is insufficient, resulting in the magnetic fillers in the magnetic dielectric metal-coated laminate not forming a suitable orientation structure, thus failing to improve the permeability and dielectric constant. If the field strength of the magnetic field is too high, it is difficult to form a magnetic field with rotational characteristics, thereby weakening the force of the magnetic field on the anisotropic magnetic fillers, and the magnetic dielectric properties of the sheet are not significantly improved.

[0084] In this invention, the first magnet and the second magnet in the n magnet groups can be the same or different magnets, and are more preferably the same magnets. The positional relationship between the N pole and the S pole of the magnets can satisfy the requirements of this invention for forming a specific magnetic field.

[0085] Preferably, the time for applying the magnetic field is less than the time for hot pressing, and the start time of applying the magnetic field is the same as the start time of hot pressing.

[0086] In this invention, the starting time of applying the magnetic field is the same as the starting time of hot pressing. That is, the magnetic field is applied in a specific way at the beginning of hot pressing, so that the anisotropic magnetic filler in the magnetic dielectric sheet is oriented and aligned under the coupling effect of a specific magnetic field, temperature and pressure, forming a neat and orderly high-orientation structure in the magnetic dielectric metal foil laminate. As hot pressing continues, the resin in the magnetic dielectric sheet gradually solidifies, and the anisotropic magnetic filler no longer moves. Therefore, it is not necessary to apply the magnetic field in the later stage of hot pressing, and the time for applying the magnetic field is less than the time for hot pressing.

[0087] Preferably, the duration of the applied magnetic field is 5-30 minutes, for example, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 22 minutes, 25 minutes or 28 minutes, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0088] Preferably, the hot pressing time is 30-300 min, for example, it can be 60 min, 80 min, 100 min, 120 min, 150 min, 180 min, 200 min, 220 min, 240 min, 260 min or 280 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 30-180 min is further preferred.

[0089] Preferably, the hot pressing temperature is 150-360℃, for example, it can be 160℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, 350℃, 340℃ or 350℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 150-240℃ is further preferred.

[0090] Preferably, the pressure of the hot pressing is 1-10 MPa, for example, it can be 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa or 9 MPa, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0091] On the other hand, the present invention provides a method for improving the magnetic dielectric properties of a magnetic dielectric metal-coated foil laminate, wherein the method is the preparation method described in the first aspect. Through the coupling effect of hot pressing and a magnetic field constructed by a specific method, the anisotropic magnetic filler grains in the magnetic dielectric metal-coated foil laminate form a specific high-orientation structure. Compared with conventional hot pressing processes, the magnetic permeability and dielectric constant of the magnetic dielectric metal-coated foil laminate are significantly improved, and the magnetic loss and dielectric loss are low, resulting in high reliability and superior overall performance.

[0092] In a second aspect, the present invention provides a magnetic dielectric metal foil laminate, which is prepared by the preparation method described in the first aspect.

[0093] Thirdly, the present invention provides a circuit board comprising a magnetic dielectric metal foil laminate as described in the second aspect.

[0094] Preferably, the circuit board is a circuit board used in an antenna.

[0095] Fourthly, the present invention provides the application of a magnetically dielectric metal foil laminate as described in the second aspect or a circuit board as described in the third aspect in an antenna.

[0096] Preferably, the antenna includes a microstrip antenna.

[0097] Compared with the prior art, the present invention has the following beneficial effects:

[0098] (1) In the preparation method provided by the present invention, a magnetic dielectric plate containing anisotropic magnetic filler is used, and a magnetic field is applied in a specific way during the hot pressing process. Under the multiple coupling effects of temperature, pressure and magnetic field during hot pressing, the anisotropic magnetic filler is oriented and arranged to form a neat and orderly high orientation structure in the plate, thereby significantly improving the permeability and dielectric constant of the magnetic dielectric metal foil laminate, while the magnetic loss and dielectric loss are low, and the heat resistance and reliability are good. This solves the problems of low permeability, poor impedance matching, insufficient miniaturization factor, narrow antenna bandwidth, low gain and design difficulty in the prior art, and obtains a magnetic dielectric metal foil laminate with high permeability, high dielectric constant, low magnetic loss, low dielectric loss and high reliability, which fully meets the performance requirements of the substrate in miniaturized antennas.

[0099] (2) Through the design and process optimization of hot pressing and magnetic field, the present invention achieves a magnetic permeability of 1.60-2.48 and a dielectric constant of 4.6-6.25 at 300MHz. Compared with the conventional hot pressing process without applying a magnetic field, the magnetic permeability is increased by 15%-25% and the dielectric constant is increased by 3.6%-9.5%. Moreover, the magnetic loss is ≤0.038 and the dielectric loss is ≤0.055. With the significant improvement in both dielectric constant and magnetic permeability, it has low magnetic loss and low dielectric loss, and excellent reliability and comprehensive performance. Attached Figure Description

[0100] Figure 1 This is a schematic diagram of the structure of a second magnetic field generating device in a specific embodiment of the present invention;

[0101] Wherein, 1-magnet, 2-magnet, and A-complex placement;

[0102] Figure 2 This is a schematic diagram of the structure of a third magnetic field generating device in a specific embodiment of the present invention;

[0103] Among them, 10 - first magnet group, 11 - first magnet of first magnet group, 12 - second magnet of first magnet group, 20 - second magnet group, 21 - first magnet of second magnet group, 22 - second magnet of second magnet group, and A - placement position of complex. Detailed Implementation

[0104] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0105] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0106] In this invention, features specified as "first" and "second" may explicitly or implicitly include one or more of these features, used to distinguish and describe features, without any order or emphasis. In the description of this invention, unless otherwise stated, "multiple" means two or more.

[0107] In one specific embodiment, a magnetic field is applied using method B, and a schematic diagram of the device for generating the second magnetic field is shown below. Figure 1 As shown, it includes a magnet 1 and a magnet 2. The magnet 1 rotates under the drive of a motor, which in turn drives the magnet 2 to rotate as well. The position A between the magnet 1 and the magnet 2 is the placement position of the composite material to be hot-pressed.

[0108] In one specific embodiment, a magnetic field is applied using method C. A schematic diagram of the third magnetic field generating device is shown below. Figure 2 As shown, the system includes two magnet groups with coincident center points: a first magnet group 10 and a second magnet group 20, with an included angle of 90°. The first magnet group 10 consists of a first magnet 11 and a second magnet 12, with the N pole of the first magnet 11 and the S pole of the second magnet 12 facing each other to form a first sub-magnetic field. The second magnet group 20 consists of a first magnet 21 and a second magnet 22, with the N pole of the first magnet 21 and the S pole of the second magnet 22 facing each other to form a second sub-magnetic field. The center points of the first and second sub-magnetic fields also coincide, and the first and second sub-magnetic fields work together to form a rotating magnetic field. Point A is the location where the composite to be hot-pressed is placed.

[0109] The specific information of the materials used in the following specific embodiments of the present invention is as follows:

[0110] (1) Resin

[0111] Polyphenylene oxide resin: SABIC SA9000;

[0112] Polybutadiene resin: Nippon Soda B3000;

[0113] Bismaleimide resin (D939): Sichuan Dongcai.

[0114] (2) Accelerator: Benzoyl peroxide, BPO, purchased from Merck Chemicals.

[0115] (3) Anisotropic magnetic filler: planar hexagonal ferrite Co2Z type, median particle size D 50 The size is 3-5μm, purchased from Shaanxi Yinghe.

[0116] (4) Isotropic magnetic filler: spinel ferrite, median particle size D 50 The size is 3-5μm, purchased from Shaanxi Yinghe.

[0117] (5) Reinforcing material: Non-woven fabric, 75g / m 2 Purchased from Shaanxi Huate.

[0118] (6) Copper foil: HVLP Luxembourg BF-TZA copper foil.

[0119] (7) Magnet used to form the second magnetic field in method B

[0120] Magnetic particle B1 is cylindrical, with a length of 10 mm and a diameter of 6 mm, and a surface electric field strength of 10 mT.

[0121] The magnetic particle B2 is olive-shaped, 20 mm in length, and has a surface electric field strength of 40 mT.

[0122] (8) The magnet used to form the second magnetic field in method B

[0123] Magnet B, 6mm×10mm, surface field strength 10mT, Bikman Biotechnology Co., Ltd.

[0124] (9) The magnet used to form the third magnetic field in method C

[0125] Magnet C1 has a surface electric field strength of 0.5T;

[0126] Magnet C2 has a surface electric field strength of 0.2T.

[0127] In this invention, the surface field strength of the magnet and the field strength generated by the magnetic field generating device are obtained by measuring the magnetic field strength using a magnetic field strength tester (DW-733, digital display millitalas meter).

[0128] Example 1

[0129] A magnetic dielectric copper-clad laminate (magnetically dielectric copper-clad laminate) and its preparation method are disclosed. The preparation method comprises the following steps:

[0130] (1) Preparation of prepreg:

[0131] The prepreg includes a reinforcing material and a magnetic dielectric resin composition attached thereto, the magnetic dielectric resin composition comprising, by weight: 30 parts polyphenylene ether SA900, 60 parts polybutadiene B3000, 10 parts bismaleimide resin D939, 0.1 parts accelerator BPO, and 50 parts planar hexagonal ferrite.

[0132] The magnetic dielectric resin composition was mixed with xylene / butanone (mass ratio 1:1) according to the aforementioned formula, and the mixture was mixed evenly at room temperature to prepare a resin solution with a solid content of 65%. The resin solution was impregnated with a reinforcing material and then dried in an oven at 130°C for 3 minutes to obtain a prepreg.

[0133] (2) Preparation of magnetic dielectric copper clad laminate:

[0134] Three prepreg sheets are stacked together, and copper foil is placed on both sides to obtain a composite. The composite is then placed in a vacuum press for hot pressing. A magnetic field with a strength of 10 mT is applied simultaneously with the start of hot pressing. The composite rotates at a speed of 10 r / min in the magnetic field for 15 min. The hot pressing temperature is 200℃, the pressure is 5 MPa, and the time is 120 min to obtain a magnetic dielectric copper-clad laminate. The start time of applying the magnetic field and the rotation is the same as the start time of hot pressing, that is, a magnetic field of 200℃, 5 MPa, and 10 mT is applied to the composite in the vacuum press simultaneously, and the composite rotates under the drive of a motor. After 15 min, the motor is turned off and the magnetic field is removed. Hot pressing at 200℃ and 5 MPa is continued for 105 min to obtain a magnetic dielectric copper-clad laminate (denoted as "copper-clad laminate A").

[0135] In comparison, the same composite material and copper foil as in Example 1 were used to prepare the same composite material. The composite material was hot-pressed at 200°C and 5MPa for 120 min without the application of a magnetic field to obtain a magnetic dielectric copper clad laminate (denoted as "copper clad laminate B") obtained by conventional hot pressing process.

[0136] The following performance tests were performed on copper-clad laminate A provided in Example 1 and copper-clad laminate B as a comparison:

[0137] (1) Permeability and magnetic loss tangent: The test was conducted using an impedance analyzer. The test instrument was a Keysight E4991B impedance analyzer with a 16454A test fixture. The test frequency was 300MHz and the test temperature was 25℃.

[0138] (2) Dielectric constant Dk and dielectric loss factor Df: The dielectric constant Dk and dielectric loss factor Df of the copper-clad laminate were tested using a Keysight E4991B impedance analyzer + 16453A test fixture at a frequency of 300MHz.

[0139] The test results are shown in Table 1.

[0140] Examples 2-9, Comparative Examples 1-4

[0141] A magnetic dielectric copper-clad laminate and its preparation method differ from Example 1 in that the formulation of the magnetic dielectric resin composition and / or the preparation process parameters are different, as shown in Tables 1 and 2. The unit for the amount of the magnetic dielectric resin composition is "parts," and "--" indicates that the component was not added or the condition was not applied. Parameters not shown in Tables 1 and 2 are the same as in Example 1, and the performance testing method for the copper-clad laminate is the same as in Example 1.

[0142] In Tables 1 and 2, the test data marked "A" are the test data of the copper-clad laminate provided in this embodiment, and the test data marked "B" are the test data of the copper-clad laminate prepared under conditions without a magnetic field applied; the improvement rate = 100% × (test value A - test value B) / test value B.

[0143] Table 1

[0144]

[0145]

[0146] Table 2

[0147]

[0148]

[0149] The preparation method of Comparative Example 3 in Table 2 is as follows: the composite is first treated in a magnetic field for 15 minutes. No hot pressing is performed during the magnetic field treatment stage, that is, the temperature is room temperature and there is no pressure. After the composite is treated in a magnetic field for 15 minutes, it is transferred to a vacuum press (no magnetic field during the hot pressing process) and hot pressed at 200℃ and 5MPa for 120 minutes to obtain a magnetic dielectric copper-clad laminate. No magnetic field is applied during the preparation of Comparative Example 4, and a conventional hot pressing process is used.

[0150] According to the performance test data in Tables 1 and 2, this invention applies a magnetic field using a specific method during the hot pressing process. Under the multiple coupling effects of temperature, pressure, and magnetic field during hot pressing, anisotropic magnetic fillers are oriented and arranged, forming a neat and orderly high-orientation structure in the magnetic dielectric copper-clad laminate. As a result, the magnetic permeability of the obtained copper-clad laminate is 1.60-2.48, and the dielectric constant is 4.6-6.25. Compared with the conventional hot pressing process without applying a dynamic magnetic field (using the same raw materials for preparing the board), the magnetic permeability is increased by 15%-25%, the dielectric constant is increased by 3.6%-9.5%, the magnetic loss of the board is 0.028-0.038, and the dielectric loss is 0.048-0.055. While the dielectric constant and magnetic permeability are increased, the dielectric loss and magnetic loss remain unchanged, resulting in good heat resistance and reliability. According to the preparation process and test results of Examples 1-9, it can be seen that by setting and adjusting parameters such as the field strength of the magnetic field and the rotation speed of the sample, the improvement effect of the magnetic dielectric properties of the copper-clad laminate can be adjusted. The rotation speed of the sample in Example 8 was too fast, and the rotation speed of the sample in Example 9 was too slow, which affected the effect of magnetic field treatment and resulted in an insignificant improvement in magnetic permeability.

[0151] This invention couples hot pressing with a specific magnetic field, causing anisotropic magnetic fillers to align under the combined effects of temperature, pressure, and magnetic field, forming a neat and orderly structure in the copper-clad laminate (CCL) and imparting higher permeability and dielectric constant. In Comparative Example 1, only a magnetic field was applied, but the sample was not rotated, resulting in the magnetic field acting on the anisotropic magnetic filler lacking dynamic characteristics. The resulting CCL had the same performance as that obtained by conventional hot pressing. In Comparative Example 2, isotropic spinel ferrite was used, which is a non-oriented magnetic filler. Even with a magnetic field, it did not affect the alignment of the magnetic filler, and the resulting CCL had the same performance as that obtained by conventional hot pressing. In the preparation method of Comparative Example 3, the composite was first subjected to magnetic field treatment while rotating, then the magnetic field was removed, and pressure and temperature were applied for hot pressing to obtain the CCL. Because the magnetic field and pressure / temperature were applied stepwise, the anisotropic magnetic filler could not form a good orientation structure, and the performance difference between the resulting CCL and that obtained by conventional hot pressing was not significant. Comparative Example 4 uses a conventional hot-pressing process and increases the magnetic permeability of the board by adding magnetic fillers. However, the increase in magnetic permeability is accompanied by a significant increase in magnetic loss and dielectric loss, resulting in poor overall magnetic and dielectric performance of the board.

[0152] Example 10

[0153] A magnetic dielectric copper-clad laminate and its preparation method, wherein the preparation method comprises the following steps:

[0154] (1) Preparation of prepreg:

[0155] The prepreg includes a reinforcing material and a magnetic dielectric resin composition attached thereto, the magnetic dielectric resin composition comprising, by weight: 20 parts polyphenylene ether SA900, 60 parts polybutadiene resin B3000, 20 parts bismaleimide resin D939, 0.05 parts accelerator BPO, and 50 parts planar hexagonal ferrite.

[0156] The magnetic dielectric resin composition was mixed with xylene / butanone (mass ratio 1:1) according to the aforementioned formula, and the mixture was mixed evenly at room temperature to prepare a resin solution with a solid content of 65%. The resin solution was impregnated with a reinforcing material and then dried in an oven at 150°C for 5 minutes to obtain a prepreg.

[0157] (2) Preparation of magnetic dielectric copper clad laminate:

[0158] Three prepreg sheets are stacked together, and copper foil is covered on the top and bottom sides to obtain a composite. The composite is placed in a vacuum press for hot pressing. A magnetic field is applied at the beginning of the hot pressing. The hot pressing temperature is 200°C, the pressure is 5MPa, and the time is 120min to obtain a magnetic dielectric copper-clad laminate.

[0159] A schematic diagram of the device for applying the magnetic field in this embodiment is shown below. Figure 1 As shown, the device includes magnet 1 (specifically magnet B, with a surface field strength of 10 mT) and magnet 2 (specifically magnet B1, cylindrical, with a length of 10 mm and a diameter of 6 mm, and a surface field strength of 10 mT). Magnet 1 rotates under the drive of a motor at a speed of 1000 r / min, which also drives magnet 2 to rotate. The magnetic field strength is 2 mT, and the application time is 15 min. The starting time of the magnetic field application is the same as the starting time of the hot pressing, that is, a magnetic field of 200℃, 5 MPa and 5 mT is applied to the composite in the vacuum press simultaneously. After 15 min, the motor is turned off and the magnetic field is removed. The hot pressing continues at 200℃ and 5 MPa for 105 min to obtain a magnetic dielectric copper-clad laminate (denoted as "copper-clad laminate A").

[0160] In contrast, the same composite material and copper foil were prepared using the same prepreg and copper foil as in this embodiment. The composite material was then hot-pressed at 200°C and 5MPa for 120 min without the application of a magnetic field to obtain a magnetic dielectric copper-clad laminate (referred to as "copper-clad laminate B") obtained by conventional hot-pressing process.

[0161] Example 11

[0162] A magnetic dielectric copper clad laminate and its preparation method are disclosed. The only difference between this laminate and Example 10 is the parameter of the applied magnetic field. The magnetic particle used is a B2 (olive-shaped, 20 mm long, with a surface field strength of 40 mT), the rotation speed of the magnet is 500 r / min, the magnetic field strength is 20 mT, and the application time is 15 min. All other materials, steps, and process parameters are the same as in Example 10.

[0163] Example 12

[0164] A magnetic dielectric copper clad laminate and its preparation method are disclosed. The only difference between this laminate and Example 10 is the parameter of the applied magnetic field. The magnetic particle used is a B2 (olive-shaped, 20 mm long, with a surface field strength of 40 mT), the rotation speed of the magnet is 100 r / min, the strength of the magnetic field is 10 mT, and the application time is 15 min. All other materials, steps, and process parameters are the same as in Example 10.

[0165] Example 13

[0166] A magnetic dielectric copper-clad laminate and its preparation method, wherein the preparation method comprises the following steps:

[0167] (1) Preparation of prepreg:

[0168] The prepreg includes a reinforcing material and a magnetic dielectric resin composition attached thereto, the magnetic dielectric resin composition comprising, by weight: 20 parts polyphenylene ether SA900, 60 parts polybutadiene resin B3000, 20 parts bismaleimide resin D939, 0.05 parts accelerator BPO, and 50 parts planar hexagonal ferrite.

[0169] The magnetic dielectric resin composition was mixed with xylene / butanone (mass ratio 1:1) according to the aforementioned formula, and the mixture was mixed evenly at room temperature to prepare a resin solution with a solid content of 65%. The resin solution was impregnated with a reinforcing material and then dried in an oven at 150°C for 5 minutes to obtain a prepreg.

[0170] (2) Preparation of magnetic dielectric copper clad laminate:

[0171] Three prepreg sheets are stacked together, and copper foil is covered on the top and bottom sides to obtain a composite. The composite is placed in a vacuum press for hot pressing. A magnetic field is applied at the beginning of the hot pressing. The hot pressing temperature is 200°C, the pressure is 5MPa, and the time is 120min to obtain a magnetic dielectric copper-clad laminate.

[0172] A schematic diagram of the device for applying the magnetic field in this embodiment is shown below. Figure 2As shown, the system includes a first magnet group 10 and a second magnet group 20 with two coincident center points, and the included angle between the two magnet groups is 90°. The first magnet group 10 consists of a first magnet 11 and a second magnet 12, with the N pole of the first magnet 11 and the S pole of the second magnet 12 facing each other to form a first sub-magnetic field. The second magnet group 20 consists of a first magnet 21 and a second magnet 22, with the N pole of the first magnet 21 and the S pole of the second magnet 22 facing each other to form a second sub-magnetic field. The center points of the first and second sub-magnetic fields coincide, and the first and second sub-magnetic fields work together to form a rotating magnetic field. Point A is the position where the composite to be hot-pressed is placed. The four magnets in the aforementioned two magnet groups are the same magnet, all of which are magnet C1 (surface field strength of 0.5T). The distance between the N pole of the first magnet 11 and the S pole of the second magnet 12 is 20cm, and the distance between the N pole of the first magnet 21 and the S pole of the second magnet 22 is 20cm. The magnetic field strength generated by the generating device (i.e., the magnetic field strength applied to the composite) is 15 mT, and the application time is 15 min. The starting time of applying the dynamic magnetic field is the same as the starting time of hot pressing, that is, a dynamic magnetic field of 200°C, 5 MPa and 20 mT is applied to the composite in the vacuum press simultaneously. After 15 min, the motor is turned off and the dynamic magnetic field is removed. Hot pressing at 200°C and 5 MPa continues for 105 min to obtain a magnetic dielectric copper-clad laminate (denoted as "copper-clad laminate A").

[0173] In contrast, the same composite material and copper foil were prepared using the same prepreg and copper foil as in this embodiment. The composite material was then hot-pressed at 200°C and 5MPa for 120 min without the application of a dynamic magnetic field to obtain a magnetic dielectric copper-clad laminate (referred to as "copper-clad laminate B") obtained by conventional hot-pressing process.

[0174] Example 14

[0175] A magnetic dielectric copper-clad laminate and its preparation method are disclosed. The only difference between this laminate and Example 13 is the parameter of the applied magnetic field. All four magnets in the two magnet groups are magnet C2 (surface field strength 0.2T). The distance between the N pole of the first magnet 11 and the S pole of the second magnet 12 is 20cm, and the distance between the N pole of the first magnet 21 and the S pole of the second magnet 22 is 20cm. The strength of the magnetic field generated by this device (i.e., the strength of the magnetic field applied to the composite) is 20mT, and the application time is 15min. All other materials, steps, and process parameters are the same as in Example 13.

[0176] Example 15

[0177] A magnetic dielectric copper-clad laminate and its preparation method are disclosed. The only difference between this laminate and Example 13 is the parameter of the applied magnetic field. All four magnets in the two magnet groups are magnet C2 (surface field strength 0.2T). The distance between the N pole of the first magnet 11 and the S pole of the second magnet 12 is 10cm, and the distance between the N pole of the first magnet 21 and the S pole of the second magnet 22 is 10cm. The strength of the magnetic field generated by this device (i.e., the strength of the magnetic field applied to the composite) is 5mT, and the application time is 15min. All other materials, steps, and process parameters are the same as in Example 13.

[0178] The same test method as in Example 1 was used to perform performance tests on the magnetic dielectric copper-clad laminates provided in Examples 10-15. The data are shown in Table 3.

[0179] Table 3

[0180]

[0181]

[0182] Based on the performance test data in Table 3, it can be seen that in Examples 10-12, method B is used to apply a magnetic field, forming a dynamic magnetic field between the magnet and the rotating magnet. In Examples 13-15, method C is used to apply a magnetic field, and the two sub-magnetic fields generated by the two sets of magnets are coupled to each other and form a magnetic field with dynamic characteristics according to the characteristics of the magnetic field lines. The hot-pressed composite is located in the aforementioned specific magnetic field. The anisotropic magnetic filler is oriented and arranged under the coupled synergistic effect of the magnetic field, the temperature and pressure of hot pressing, forming a specific high orientation structure. As a result, the dielectric constant of the magnetic dielectric copper clad laminate is increased by 5%-8%, the magnetic permeability is increased by 13%-16%, and the dielectric loss and magnetic loss remain unchanged, with good heat resistance and reliability.

[0183] The applicant declares that this invention illustrates the magnetic dielectric coated metal foil laminate, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above process steps, meaning that this invention does not necessarily rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A method for preparing a magnetically dielectric metal foil laminate, characterized in that, The preparation method includes: A magnetic dielectric sheet is provided; the magnetic dielectric sheet comprises at least one prepreg, the prepreg comprising a reinforcing material and a magnetic dielectric resin composition attached to the reinforcing material; the magnetic dielectric resin composition comprises a combination of resin and anisotropic magnetic filler; A composite material is obtained by laminating a metal foil onto one or both sides of the magnetic dielectric substrate; The composite is hot-pressed to obtain the magnetic dielectric metal foil laminate; A magnetic field is applied during the hot pressing process, and the method of applying the magnetic field includes any one of method A, method B or method C; Method A includes: placing the composite in a non-magnetic mold located in a first magnetic field, the non-magnetic mold rotating in the first magnetic field; the rotation speed of the non-magnetic mold is 10-100 r / min; the field strength of the first magnetic field is 10-50 mT; Method B includes: placing the composite material between a magnet and a rotating magnet, forming a second magnetic field between the magnet and the rotating magnet; the rotational speed of the magnet is 100-2500 r / min; the field strength of the second magnetic field is 2-20 mT. Method C includes: placing the composite material in a third magnetic field, wherein the device generating the third magnetic field comprises n groups of magnets with coincident center points, where n is an integer ≥2; each group of magnets is independently composed of a first magnet and a second magnet, wherein the N pole of the first magnet and the S pole of the second magnet in each group of magnets are arranged opposite each other, and a third magnetic field is formed between the N pole and the S pole; the included angle between any two adjacent groups of magnets is equal; the distance between the N pole of the first magnet and the S pole of the second magnet in each group of magnets is 2-60 cm; and the field strength of the third magnetic field is 5-30 mT. The time for applying the magnetic field is less than the time for hot pressing, and the starting time for applying the magnetic field is the same as the starting time for hot pressing; the time for applying the magnetic field is 5-30 min.

2. The preparation method according to claim 1, characterized in that, The anisotropic magnetic filler includes one or a combination of two of planar hexagonal ferrite and magnetoplumbago ferrite.

3. The preparation method according to claim 2, characterized in that, The planar hexagonal ferrite includes any one or a combination of at least two of the following: Y-type planar hexagonal ferrite, Co2Z-type planar hexagonal ferrite, and Co2W-type planar hexagonal ferrite.

4. The preparation method according to claim 1, characterized in that, The median particle size of the anisotropic magnetic filler is 0.1-30 μm.

5. The preparation method according to claim 4, characterized in that, The median particle size of the anisotropic magnetic filler is 1-15 μm.

6. The preparation method according to claim 1, characterized in that, The anisotropic magnetic filler content in the magnetic dielectric resin composition is 10%-80% by mass.

7. The preparation method according to claim 1, characterized in that, The resin includes any one or a combination of at least two of the following: epoxy resin, phenolic resin, cyanate ester resin, polyphenylene ether resin, polyolefin resin, styrene-butadiene resin, phenolic resin, fluorinated resin, and benzoxazine resin.

8. The preparation method according to claim 1, characterized in that, The magnetic dielectric resin composition further includes any one or a combination of at least two of the following: curing agent, accelerator, crosslinking agent, initiator, flame retardant, coupling agent, and non-magnetic filler.

9. The preparation method according to claim 1, characterized in that, The number of prepreg sheets in the magnetic dielectric sheet is 1-20.

10. The preparation method according to claim 1, characterized in that, The magnetic dielectric resin composition is attached to the reinforcing material after impregnation and drying to obtain a prepreg.

11. The preparation method according to claim 1, characterized in that, The reinforcing material includes any one of glass fiber cloth, non-woven fabric, quartz cloth, quartz glass fiber blended fabric, or fiber paper.

12. The preparation method according to claim 1, characterized in that, The metal foil includes any one or a combination of at least two of the following: copper foil, aluminum foil, nickel foil, and alloy foil.

13. The preparation method according to claim 12, characterized in that, The metal foil is copper foil.

14. The preparation method according to claim 1, characterized in that, In method B, the surface field strength of the magnetic particle is 10-100 mT.

15. The preparation method according to claim 1, characterized in that, In method C, the surface field strength of the first magnet and the second magnet are each independently 0.1 mT-1 T.

16. The preparation method according to claim 1, characterized in that, The hot pressing time is 30-300 min.

17. The preparation method according to claim 1, characterized in that, The hot pressing temperature is 150-360℃.

18. The preparation method according to claim 17, characterized in that, The hot pressing temperature is 150-240℃.

19. The preparation method according to claim 1, characterized in that, The pressure of the hot pressing is 1-10 MPa.

20. A magnetically dielectric metal foil laminate, characterized in that, The magnetic dielectric clad metal foil laminate is prepared by the preparation method according to any one of claims 1-19.

21. A circuit board, characterized in that, The circuit board includes the magnetic dielectric metal foil laminate as described in claim 20.

22. The application of a magnetically dielectric metal foil laminate as described in claim 20 or a circuit board as described in claim 21 in an antenna.

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