A metal-clad laminate, a method for manufacturing the same, and a printed circuit board using the same

Abstract

The application provides a metal-clad laminate and a preparation method and application thereof, and the preparation method comprises the following steps: compounding a metal foil on one side or two sides of a magnetic dielectric plate to obtain a compound; and hot-pressing the compound to obtain a metal-clad laminate; a dynamic magnetic field is applied in the process of hot-pressing, and a dynamic magnetic field generating device comprises a magnetic sub and a rotating magnet, and the magnetic sub rotates under the driving of the magnet; the magnetic dielectric plate material comprises at least one magnetic dielectric prepreg, and the magnetic dielectric prepreg comprises a reinforcing material and a magnetic dielectric resin composition attached to the reinforcing material, and the magnetic dielectric resin composition comprises a combination of a resin and an anisotropic magnetic filler. Through the coupling effect of the dynamic magnetic field and the hot-pressing, a metal-clad laminate with high magnetic permeability, high dielectric constant, low magnetic loss, low dielectric loss and high reliability is obtained, and the performance requirements of the substrate in a small antenna are fully met.

Description

Technical Field

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

[0002] With the rapid development of modern wireless communication services, the demand for antenna miniaturization and wide bandwidth is becoming increasingly urgent. Microstrip antennas, with their advantages of thin profile, small size, light weight, simple structure, and ease of integration with active devices, are widely used in modern wireless technologies such as GSM, GPS, and Bluetooth. To further reduce the size of microstrip antennas, researchers have proposed many theoretical solutions. One approach is to modify the antenna patch and its geometry and structure, such as adding short-circuit probes to the dielectric, slotting the patch, adding capacitors or resistors, or using butterfly-shaped patches. Another approach is to use dielectrics or magnetic materials with high dielectric constants. Since the resonant frequency of a microstrip antenna is inversely proportional to the square root of the product of the equivalent dielectric constant and permeability of the dielectric, using a dielectric with a high dielectric constant as the substrate can reduce the antenna size. Using magnetic materials such as ferrite substrates can also significantly reduce the antenna size. However, there is an unavoidable contradiction in microstrip antenna design: reducing size while obtaining a wider operating bandwidth and high gain. Using a high dielectric constant as the substrate can reduce the antenna size, but at the same time, it will narrow the antenna bandwidth and reduce the gain. Ferrite has too much loss in the microwave band. Therefore, microstrip antennas made of ferrite materials are usually used in the ultra-high frequency band. Using multilayer structures or adding capacitors and resistors will complicate the antenna structure and make it lose its practical value.

[0003] For a miniaturized antenna of a given size, the antenna bandwidth can be improved by increasing the permeability. Therefore, magnetoelectric materials have significant advantages in broadband antenna design. Researchers have achieved diversification of permeability and dielectric constant through the design of dielectric substrates, thereby meeting the performance requirements of dielectric constant and permeability of dielectric materials in miniaturized microwave device applications. For example, CN106797699A discloses a magnetic dielectric substrate, circuit material, and component. The magnetic dielectric 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 a ferrite material. In this magnetic dielectric substrate, the introduction of the magnetic reinforcement layer gives it magnetoelectronic properties combined with good mechanical 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 magnetic filler content to the inorganic filler material is 0.3-3.0, thereby increasing the magnetic permeability of the insulating layer, reducing magnetic loss, and providing good insulation and reliability. CN109553955A discloses a magnetic dielectric resin composition and prepreg, laminate, and copper-clad laminate containing the composition. The magnetic dielectric resin composition comprises 30-100 parts by weight of resin and 50-500 parts by weight of magnetic filler. The resistivity of the magnetic filler is 100 Ω·M-1000 Ω·M, and the permeability is 5-1000, giving the copper-clad laminate containing the composition good magnetic properties and insulation.

[0004] With the miniaturization of dielectric substrates and antennas, existing magnetic dielectric materials have revealed many shortcomings in terms of properties such as dielectric constant and permeability. Improving dielectric constant and permeability is difficult, impedance matching is poor, and miniaturization factors are insufficient. Furthermore, increasing dielectric constant and permeability is accompanied by problems such as increased magnetic loss, increased dielectric loss, and decreased reliability, which greatly limits the application of magnetic dielectric materials in communication equipment and electronic products. Therefore, developing a magnetic dielectric material with high permeability and dielectric constant and low loss is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a metal-clad laminate, its preparation method, and its application. By applying a dynamic magnetic field during the hot pressing process, the resulting metal-clad laminate exhibits significantly improved magnetic permeability and dielectric constant, as well as low magnetic and dielectric losses, and excellent magnetic-dielectric properties and reliability.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a metal foil-coated laminate, the method comprising the following steps: laminating a metal foil onto one or both sides of a magnetic dielectric substrate to obtain a composite; hot-pressing the composite to obtain the metal foil-coated laminate; applying a dynamic magnetic field during the hot-pressing process, the device for generating the dynamic magnetic field comprising a magnet and a rotating magnet, the magnet rotating under the drive of the magnet; a dynamic magnetic field being formed between the magnet and the magnet; the magnetic dielectric substrate comprising at least one magnetic dielectric prepreg, the magnetic dielectric 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.

[0008] In the method for preparing the metal foil laminate provided by this invention, a dynamic magnetic field is applied during hot pressing. This causes the anisotropic magnetic filler (orientable magnetic filler) in the magnetic dielectric substrate to align under the influence of the dynamic magnetic field. Under the combined effects of temperature, pressure, and the dynamic magnetic field during hot pressing, the anisotropic magnetic filler in the magnetic dielectric substrate forms a specific "leaf-like" structure. This makes the arrangement of the anisotropic magnetic filler grains more orderly and the orientation higher, thereby significantly improving the permeability and dielectric constant of the metal foil laminate. Simultaneously, it exhibits low magnetic and dielectric losses, as well as 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 in the prior art through the coupling effect of the dynamic magnetic field and hot pressing. It obtains a metal foil laminate with high permeability, high dielectric constant, low magnetic loss, low dielectric loss, and high reliability, fully meeting the performance requirements of the substrate in miniaturized antennas.

[0009] In this invention, the dynamic magnetic field generating device includes a magnetic particle and a rotating magnet. The magnetic particle rotates under the coupling drive of the rotating magnet, and a dynamic 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 between the dynamic magnetic field (the rotating magnet and the rotating magnetic particle), thereby applying the dynamic magnetic field during the hot-pressing process, coupling the effects of the temperature, pressure, and 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 from the hot-pressing device on the interaction between the dynamic magnetic field and the anisotropic magnetic filler, which would affect the improvement of the magnetic permeability of the metal-coated foil laminate.

[0010] In this invention, the magnetic particle in the dynamic magnetic field generating device 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 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 the dynamic magnetic field generating device of this invention.

[0011] 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).

[0012] Preferably, 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.

[0013] Preferably, 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.

[0014] Preferably, the surface field strength of the magnetic particle 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.

[0015] Preferably, the magnet rotates under the drive of a motor.

[0016] Preferably, 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, 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.

[0017] As a preferred embodiment of the present invention, the magnet rotates under the drive of a motor, with a rotation speed of 1-2500 r / min driven by the electrodes, more preferably 100-2500 r / min, which can effectively drive the magnet to rotate and form a suitable dynamic magnetic field between the magnet and the magnet. If the rotation speed is too low, the magnet cannot be effectively driven to rotate, and a suitable dynamic magnetic field cannot be formed; if the rotation speed is too high, the oriented anisotropic magnetic filler will have completed a new revolution before it can move effectively under the action of high rotation speed, and the anisotropic magnetic filler will not undergo a suitable orientation, resulting in insignificant or ineffective dynamic processing, and thus failing to improve the permeability and dielectric constant of the metal-clad laminate.

[0018] In this 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 form a dynamic magnetic field.

[0019] Preferably, the field strength of the dynamic 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.

[0020] In this invention, the field strength of the dynamic magnetic field is the field strength of the dynamic magnetic field acting on the hot-pressed composite. The "field strength" is combined with "rotation (dynamic)," and coupled with the temperature and pressure effects of hot pressing, causing the anisotropic magnetic fillers in the magnetic dielectric substrate to oriented and form a neat and orderly specific leaf-like structure in the metal-clad laminate. This high degree of orientation endows the metal-clad laminate with higher permeability and dielectric constant, while simultaneously exhibiting low magnetic and dielectric losses, resulting in excellent overall performance. If the field strength of the dynamic magnetic field is too low or the rotation speed is too slow, a suitable dynamic magnetic field cannot be formed, leading to low orientation of the anisotropic magnetic fillers and thus failing to improve permeability. Conversely, if the field strength of the dynamic magnetic field is too high or the rotation speed is too fast, the anisotropic magnetic fillers will have completed a new rotation before effectively moving under the high magnetic field / high rotation speed, resulting in insignificant or ineffective dynamic processing, and a lack of noticeable improvement in the permeability and dielectric constant of the metal-clad laminate.

[0021] Preferably, the application time of the dynamic magnetic field is less than the hot pressing time, and the starting time of applying the dynamic magnetic field is the same as the starting time of the hot pressing.

[0022] In this invention, the starting time of applying the dynamic magnetic field is the same as the starting time of the hot pressing, that is, the dynamic magnetic field is applied at the beginning of the hot pressing process. This causes the anisotropic magnetic filler in the magnetic dielectric material to align under the coupling effect of temperature, pressure, and the dynamic magnetic field, forming a neat and orderly highly oriented structure in the metal foil laminate. As the hot pressing continues, the resin in the magnetic dielectric material solidifies, preventing the anisotropic magnetic filler from moving. Therefore, the dynamic magnetic field does not need to be applied in the later stages of the hot pressing process, and the application time of the dynamic magnetic field is less than the hot pressing time.

[0023] Preferably, the application time of the dynamic magnetic field is 5-30 min, for example, it can be 6 min, 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min or 28 min, as well as specific point values ​​between the above points. 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.

[0024] 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.

[0025] Preferably, the hot pressing temperature is 150-360℃, for example, it can be 160℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 300℃, 320℃, 340℃ or 350℃, 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, and 155-280℃ is further preferred.

[0026] 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.

[0027] 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.

[0028] Preferably, the planar hexagonal ferrite includes any one or a combination of at least two of Y-type planar hexagonal ferrite, Co2Z-type planar hexagonal ferrite, and Co2W-type planar hexagonal ferrite;

[0029] 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.

[0030] For example, the particle size of the anisotropic magnetic filler was obtained by testing with an MS3000 Malvern laser particle size analyzer.

[0031] 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.

[0032] 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, benzoxazine resin, maleimide compound, phenolic resin, fluorinated resin, and benzoxazine resin.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Preferably, the magnetic dielectric resin composition comprises the following components in parts by weight:

[0039]

[0040] Specifically, the epoxy resin is 30-95 parts, for example, it can be 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts or 90 parts, 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.

[0041] The curing agent is 5-70 parts, for example, it can be 10 parts, 20 parts, 30 parts, 40 parts, 50 parts or 60 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Preferably, the reinforcing material includes any one of glass fiber cloth, quartz glass fiber blended cloth, non-woven cloth, quartz cloth, fiber paper or wood pulp paper.

[0049] Preferably, in the magnetic dielectric prepreg, the magnetic dielectric resin composition is attached to the reinforcing material after impregnation and drying.

[0050] Preferably, the method for preparing the magnetic dielectric prepreg includes: impregnating a reinforcing material with a liquid of the magnetic dielectric resin composition, and then drying it to obtain the magnetic dielectric prepreg.

[0051] 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.

[0052] 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.

[0053] Preferably, the number of sheets of magnetic dielectric prepreg in the magnetic dielectric sheet is 1-20, for example, 2, 3, 5, 7, 9, 10, 11, 13, 15, 17 or 19, and the specific point values ​​between the above point values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0054] Preferably, the metal foil includes any one of copper foil, aluminum foil, nickel foil, and alloy foil.

[0055] Preferably, the metal foil is copper foil, and the metal foil laminate is copper clad laminate.

[0056] Preferably, the preparation method specifically includes the following steps:

[0057] (1) A composite material is obtained by laminating a metal foil on one or both sides of a magnetic dielectric sheet; the magnetic dielectric sheet includes at least one magnetic dielectric prepreg, the magnetic dielectric prepreg includes a reinforcing material and a magnetic dielectric resin composition attached to the reinforcing material; the magnetic dielectric resin composition includes a combination of resin and anisotropic magnetic filler; the mass percentage of the anisotropic magnetic filler in the magnetic dielectric resin composition is 10-80%;

[0058] (2) The composite is hot-pressed to obtain the metal foil laminate;

[0059] A dynamic magnetic field is applied during the hot pressing process. The device for generating the dynamic magnetic field includes a magnetic particle and a magnet that rotates under the drive of a motor. The magnetic particle rotates under the drive of the magnet. A dynamic magnetic field is formed between the magnetic particle and the magnet. The rotation speed of the magnet is 1-2500 r / min.

[0060] The starting time of applying the dynamic magnetic field is the same as the starting time of the hot pressing. The field strength of the dynamic magnetic field is 0.1-20 mT, and the application time is 5-30 min.

[0061] The hot pressing temperature is 150-280℃, the pressure is 1-10MPa, and the time is 30-300min.

[0062] On the other hand, the present invention provides a method for improving the magnetic and dielectric properties of metal-clad laminates, wherein the method is the preparation method described in the first aspect. Through the coupling effect of hot pressing and a dynamic magnetic field, the anisotropic magnetic filler grains in the metal-clad laminate form a specific high-orientation structure. Compared with conventional hot pressing processes, the permeability and dielectric constant of the metal-clad laminate are significantly improved, and the magnetic and dielectric losses are low, resulting in superior overall magnetic and dielectric properties.

[0063] In a second aspect, the present invention provides a metal foil-coated laminate, which is prepared by the preparation method described in the first aspect.

[0064] Thirdly, the present invention provides a circuit board, characterized in that the circuit board includes a metal foil laminate as described in the second aspect.

[0065] Fourthly, the present invention provides an application of a metal foil laminate as described in the second aspect or a circuit board as described in the third aspect in a microstrip antenna.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) In the preparation method provided by the present invention, a dynamic magnetic field is applied during the hot pressing process. Under the multiple coupling effects of temperature, pressure and dynamic magnetic field during hot pressing, the anisotropic magnetic filler is oriented and arranged, forming a neat and orderly high-orientation structure in the metal foil laminate. This significantly improves the permeability and dielectric constant of the metal foil laminate, while also resulting in low magnetic loss and dielectric loss, good heat resistance and reliability. The preparation method of the present invention solves the problems of low permeability, poor impedance matching, insufficient miniaturization factor, narrow antenna bandwidth, low gain and design difficulties in the prior art, and obtains a 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.

[0068] (2) Through the design and process optimization of hot pressing and dynamic magnetic field, the present invention achieves a permeability of 2.13-2.47 and a dielectric constant of 5.74-6.36 at 300MHz. Compared with the conventional hot pressing process without applying dynamic magnetic field, the permeability is increased by 15-30% and the dielectric constant is increased by 5.1-8.1%. Moreover, the magnetic loss and dielectric loss are low, with magnetic loss ≤0.038 and dielectric loss ≤0.054, exhibiting excellent heat resistance and reliability. Detailed Implementation

[0069] 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.

[0070] The specific information of the materials used in the following specific embodiments of the present invention is as follows:

[0071] (1) Epoxy resin

[0072] Epoxy resin, SQCN703, purchased from Shandong Shengquan New Material Co., Ltd.

[0073] (2) Curing agent

[0074] Bisphenol A type phenolic resin, SH-2107, was purchased from Shandong Shengquan New Material Co., Ltd.

[0075] (3) Accelerator

[0076] 2-Methylimidazole, 2-MI, purchased from Shikoku Kasei.

[0077] (4) Anisotropic magnetic filler

[0078] Planar hexagonal ferrite, Co2Z type, median particle size D 50 The size is 3-5μm, purchased from Shaanxi Yinghe.

[0079] (5) Isotropic magnetic filler

[0080] Spinel ferrite, median grain size D 50 The size is 3-5μm, purchased from Shaanxi Yinghe.

[0081] (6) Reinforcing materials

[0082] Non-woven fabric, 75g / m 2 Epoxy nonwoven fabric, purchased from Shaanxi Huate.

[0083] (7) Copper foil

[0084] HVLP Luxembourg BF-TZA copper foil.

[0085] (8) Magnet

[0086] Magnetic particle A1 is cylindrical, with a length of 10 mm, a diameter of 6 mm, and a surface electric field strength of 10 mT; Magnetic particle A2 is cylindrical, with a length of 20 mm, a diameter of 8 mm, and a surface electric field strength of 20 mT; Magnetic particle A3 is circular, with a diameter of 30 mm, and a surface electric field strength of 30 mT.

[0087] Magnetic particle A4 is cylindrical, with a length of 20 mm and a diameter of 6 mm, and a surface electric field strength of 40 mT; Magnetic particle A5 is olive-shaped, with a length of 20 mm and a surface electric field strength of 40 mT.

[0088] Magnetic particle A6 is circular with a diameter of 20 mm and a surface electric field strength of 40 mT.

[0089] Magnetic particle A7 is cylindrical, with a length of 10 mm, a diameter of 6 mm, and a surface electric field strength of 5 mT; Magnetic particle A8 is circular, with a diameter of 20 mm, and a surface electric field strength of 100 mT.

[0090] (9) Magnet

[0091] Type A magnet, 6mm×10mm, field strength 10mT, purchased from Bikman Biotechnology Co., Ltd.

[0092] In this invention, the surface field strength of the magnet and the magnetic field generated by the magnetic field generating device is obtained by measuring the magnetic field strength using a magnetic field strength tester (DW-733, digital display millitalas meter).

[0093] Example 1

[0094] A metal foil-clad laminate (copper-clad laminate) and its preparation method are disclosed, wherein the preparation method comprises the following steps:

[0095] (1) Preparation of magnetic dielectric prepreg:

[0096] The magnetic dielectric prepreg comprises a reinforcing material and a magnetic dielectric resin composition attached thereto, the magnetic dielectric resin composition comprising, by weight: 70 parts epoxy resin, 30 parts curing agent bisphenol A phenolic resin, 0.2 parts accelerator, and 60 parts planar hexagonal ferrite.

[0097] The magnetic dielectric resin composition was mixed with methyl ethyl ketone according to the aforementioned formula and 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 magnetic dielectric prepreg.

[0098] (2) Preparation of copper clad laminate:

[0099] Three sheets of magnetic dielectric prepreg are stacked together, and copper foil is covered on the top and bottom sides to obtain a composite. The composite is then placed in a vacuum press for hot pressing at a temperature of 200°C, a pressure of 5 MPa, and a time of 120 min to obtain a copper-clad laminate.

[0100] A dynamic magnetic field is applied during the hot pressing process. The device for generating the dynamic magnetic field includes a magnetic particle A1 and a magnet that rotates at a speed of 1500 r / min driven by a motor. The magnetic particle A1 rotates under the drive of the magnet. A dynamic magnetic field is formed between the magnetic particle A1 and the magnet. The field strength of the dynamic magnetic field is 3 mT, and the application time is 15 min.

[0101] 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℃, 5MPa and 3mT is applied synchronously to the composite in the vacuum press; after 15 minutes, the motor is turned off and the dynamic magnetic field is removed, and hot pressing at 200℃ and 5MPa continues for 105 minutes to obtain copper-clad laminate (denoted as "copper-clad laminate A").

[0102] 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 dynamic magnetic field to obtain a copper-clad laminate (referred to as "copper-clad laminate B") obtained by conventional hot-pressing process.

[0103] The following performance tests were performed on copper-clad laminate A provided in Example 1 and copper-clad laminate B as a comparison:

[0104] (1) Permeability and magnetic loss tangent: Permeability was tested using an impedance analyzer. The instrument was Keysight E4991B impedance analyzer + 16454A test fixture. The frequency was 300MHz and the test temperature was 25℃.

[0105] (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 impedance analyzer E4991B+16453A test fixture at a frequency of 300MHz.

[0106] The test results are shown in Table 1.

[0107] Examples 2-10, Comparative Examples 1-5

[0108] A copper-clad laminate and its preparation method differ from Example 1 in that the formulation and / or process parameters of the magnetic dielectric resin composition 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. In Tables 1 and 2, test data marked "A" represents the test data of the copper-clad laminate provided in this example, and test data marked "B" represents the test data of the copper-clad laminate prepared under conditions without a dynamic magnetic field. Improvement rate = 100% × (Test value A - Test value B) / Test value B.

[0109] Table 1

[0110]

[0111]

[0112] Table 2

[0113]

[0114]

[0115] In Table 2, the preparation method of Comparative Example 4 is as follows: the composite is first treated in a dynamic magnetic field for 15 min. No hot pressing is performed during the dynamic magnetic field treatment stage, that is, the temperature is room temperature and there is no pressure. After the composite is treated in the magnetic field for 15 min, it is transferred to a vacuum press (no magnetic field during the hot pressing process) and hot pressed at 200℃ and 5MPa for 120 min to obtain a copper-clad laminate. No magnetic field is applied during the preparation of Comparative Example 5, and conventional hot pressing process is used.

[0116] According to the performance test data in Tables 1 and 2, the present invention applies a dynamic magnetic field during the hot pressing process. Under the multiple coupling effects of temperature, pressure, and dynamic magnetic field during hot pressing, the anisotropic magnetic filler is oriented and arranged, forming a neat and orderly high-orientation structure in the copper-clad laminate. As a result, the magnetic permeability of the obtained copper-clad laminate is 2.13-2.47, and the dielectric constant is 5.74-6.36. Compared with the conventional hot pressing process without applying a dynamic magnetic field (the raw materials for preparing the board are exactly the same), the magnetic permeability is increased by 15-30%, and the dielectric constant is increased by 5.1-8.1%. While the magnetic permeability and dielectric constant are increased, the magnetic loss and dielectric loss of the board do not change. The magnetic loss is 0.030-0.038, and the dielectric loss is 0.048-0.054. It has good heat resistance and reliability. According to the preparation process and test results of Examples 1-10, the improvement effect of the magnetic dielectric properties of copper-clad laminate can be adjusted by setting and adjusting parameters such as the rotation speed of the magnet and the field strength of the dynamic magnetic field. Under the appropriate combination of magnetic field strength and magnet rotation speed, a more significant improvement effect of magnetic permeability and dielectric constant can be obtained. If the rotation speed is too high or too low (Examples 7-8), or the magnetic field strength is too high or too low (Examples 9-10), the improvement effect of the magnetic dielectric properties of copper-clad laminate will not be obvious.

[0117] In the preparation method provided by this invention, hot pressing and a dynamic magnetic field are coupled, causing the anisotropic magnetic filler to align in an orientation under the combined effects of temperature, pressure, and the dynamic magnetic field, forming a neat and orderly structure in the copper-clad laminate, thus giving the copper-clad laminate higher permeability and dielectric constant. In Comparative Example 1, the magnet rotation speed is 0, and in Comparative Example 2, no magnet is set, so a dynamic magnetic field cannot be formed, and the copper-clad laminate obtained is the same as that obtained by conventional hot pressing. In Comparative Example 3, the magnetic dielectric resin composition uses isotropic spinel ferrite, which is a non-oriented magnetic filler. Even if a dynamic magnetic field is applied, it will not affect the arrangement of the magnetic filler, and the copper-clad laminate obtained is the same as that obtained by conventional hot pressing. In the preparation method of Comparative Example 4, the composite is first treated with a dynamic magnetic field, then the dynamic magnetic field is removed, and pressure is applied for hot pressing to obtain a copper-clad laminate. Since the dynamic magnetic field and pressure are applied stepwise, the anisotropic magnetic filler cannot form a good orientation structure. Therefore, the copper-clad laminate obtained in Comparative Example 4 has no significant performance difference compared with the copper-clad laminate obtained by conventional hot pressing. Comparative Example 5 uses a conventional hot-pressing process to increase 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.

[0118] The applicant declares that the present invention is illustrated through the above embodiments to demonstrate the metal-coated foil laminate, its preparation method, and its application. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a metal foil-coated laminate, characterized in that, The preparation method includes the following steps: laminating a metal foil onto one or both sides of a magnetic dielectric substrate to obtain a composite; hot-pressing the composite to obtain the metal foil-coated laminate. A dynamic magnetic field is applied during the hot pressing process. The device for generating the dynamic magnetic field includes a magnet and a rotating magnet, and the magnet rotates under the drive of the magnet. The magnet rotates under the drive of a motor, and the rotation speed of the magnet is 300-2500 r / min; A dynamic magnetic field is formed between the magnet and the magnet; the field strength of the dynamic magnetic field is 2-20 mT. The magnetic dielectric sheet comprises at least one magnetic dielectric prepreg, the magnetic dielectric 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; The application time of the dynamic magnetic field is less than the hot pressing time, and the starting time of applying the dynamic magnetic field is the same as the starting time of the hot pressing; the application time of the dynamic magnetic field is 5-30 min.

2. The preparation method according to claim 1, characterized in that, The surface field strength of the magnet is 10-100 mT.

3. The preparation method according to claim 1, wherein the hot pressing time is 30-300 min.

4. The preparation method according to claim 1, wherein the hot pressing temperature is 150-360℃.

5. The preparation method according to claim 1, wherein the hot pressing pressure is 1-10 MPa.

6. 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.

7. The preparation method according to claim 6, wherein the planar hexagonal ferrite comprises any one or a combination of at least two of Y-type planar hexagonal ferrite, Co2Z-type planar hexagonal ferrite, and Co2W-type planar hexagonal ferrite.

8. The preparation method according to claim 1, wherein the median particle size of the anisotropic magnetic filler is 0.1-30 μm.

9. The preparation method according to claim 8, wherein the median particle size of the anisotropic magnetic filler is 1-15 μm.

10. The preparation method according to claim 1, wherein the mass percentage of anisotropic magnetic filler in the magnetic dielectric resin composition is 10-80%.

11. 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, benzoxazine resin, phenolic resin, and fluorinated resin.

12. The preparation method according to claim 1, wherein the magnetic dielectric resin composition further comprises 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.

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

14. In the preparation method according to claim 1, the magnetic dielectric prepreg is wherein the magnetic dielectric resin composition is attached to the reinforcing material after impregnation and drying.

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

16. The preparation method according to claim 1, wherein the metal foil comprises any one of copper foil, aluminum foil, nickel foil, and alloy foil.

17. The preparation method according to any one of claims 1-16, characterized in that, The preparation method specifically includes the following steps: (1) A composite material is obtained by laminating a metal foil on one or both sides of a magnetic dielectric sheet; the magnetic dielectric sheet comprises at least one magnetic dielectric prepreg, the magnetic dielectric 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; the mass percentage of the anisotropic magnetic filler in the magnetic dielectric resin composition is 10-80%; (2) The composite is hot-pressed to obtain the metal foil laminate; A dynamic magnetic field is applied during the hot pressing process. The device for generating the dynamic magnetic field includes a magnetic particle and a magnet that rotates under the drive of a motor. The magnetic particle rotates under the drive of the magnet. A dynamic magnetic field is formed between the magnetic particle and the magnet. The rotation speed of the magnet is 300-2500 r / min. The starting time of applying the dynamic magnetic field is the same as the starting time of the hot pressing. The field strength of the dynamic magnetic field is 2-20 mT, and the application time is 5-30 min. The hot pressing temperature is 150-280℃, the pressure is 1-10 MPa, and the time is 30-300 min.

18. A metal foil-coated laminate, characterized in that, The metal foil laminate is prepared by the preparation method according to any one of claims 1-17.

19. A circuit board, characterized in that, The circuit board includes the metal foil laminate as described in claim 18.

20. The application of a metal foil laminate as described in claim 18 or a circuit board as described in claim 19 in a microstrip antenna.

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