Magnetic film and preparation method thereof, semiconductor packaging module and electronic equipment

Abstract

The present application provides a magnetic film, comprising a substrate and a composite layer. The composite layer comprises a plurality of stacked magnetic layers and a plurality of insulating dielectric layers, and the plurality of magnetic layers and the plurality of dielectric layers are stacked and arranged alternately on one side of the substrate. The thickness of each magnetic layer is 2nm-100nm; the thickness of each dielectric layer is 2nm-10nm. The composite layer comprises a plurality of cracks distributed non-periodically. At least some of the cracks extend in different directions along the cross section perpendicular to the stacking direction of the composite layer, and at least some of the cracks extend in a non-linear manner along the cross section perpendicular to the stacking direction of the composite layer. The present application also provides an electronic device and a semiconductor packaging module using the magnetic film, and a method for preparing the magnetic film. The magnetic film is an absorbing material with high magnetic permeability in the radio frequency microwave band. The magnetic film still has high magnetic permeability and high resistivity when the thickness reaches the micron level.

Description

Technical Field

[0001] The present application relates to a magnetic film and a preparation method thereof, as well as a semiconductor packaging module and electronic equipment using the magnetic film. Background Art

[0002] With the rapid development of communication and terminal technologies, electronic components and terminal devices are becoming increasingly miniaturized, compact, and multi-frequency. This results in a large number of electromagnetic waves of varying frequencies being flooded into confined spaces. This also leads to a sharp increase in electromagnetic interference between electronic components, between electronic devices, and between electronic devices and the external environment. Solutions to electromagnetic interference are generally divided into two categories: shielding and absorption. Using absorbing materials to absorb excess electromagnetic waves is a relatively preferred solution, as it avoids secondary contamination and is more convenient and flexible. However, the high integration density of electronic devices, the very limited physical space, and the complex electromagnetic environment place extremely high demands on the thickness and absorbing properties of absorbing materials. Summary of the Invention

[0003] A first aspect of an embodiment of the present application provides a magnetic film, comprising:

[0004] substrate;

[0005] a composite layer located on one side of the substrate, the composite layer comprising a plurality of stacked magnetic layers and a plurality of insulating dielectric layers, the plurality of magnetic layers and the plurality of dielectric layers being alternately arranged on one side of the substrate;

[0006] The thickness of each magnetic layer is 2nm-100nm; the thickness of each dielectric layer is 2nm-10nm; the thickness of the composite layer is 50nm-10μm; the composite layer includes multiple cracks, the multiple cracks are non-periodically distributed, at least some of the multiple cracks have different extension directions along the cross-section perpendicular to the stacking direction of the composite layer, and at least some of the multiple cracks extend non-linearly along the cross-section perpendicular to the stacking direction of the composite layer.

[0007] After adjacent magnetic layers are separated by a dielectric layer of nanometer thickness, the nanometer size effect and high proportion of interface atoms of the single-layer magnetic thin layer material can be maintained to the maximum extent, and the magnetic anisotropy caused by the shape of the nanometer-thick magnetic layer can be maintained, so that it can still have the characteristics of high magnetic permeability.

[0008] In the embodiment of the present application, the plurality of cracks are caused by the release of internal stress in the plurality of magnetic layers and the plurality of dielectric layers during the process of forming the plurality of magnetic layers and the plurality of dielectric layers by sputtering.

[0009] In the embodiment of the present application, the cracks divide the composite layer into several regions.

[0010] In the embodiment of the present application, the area of ​​each region along the cross-sectional direction is 0.001 mm 2 -0.3mm 2 .

[0011] The cracks divide the continuous composite layer into several tiny regions, significantly increasing the resistivity of the magnetic film as a whole. For example, if the magnetic film is crack-free, the resistivity is approximately 0.01 μΩm. However, in this application, the resistivity of the magnetic film as a whole with the cracks reaches 0.2 μΩm-20,000 μΩm.

[0012] In an embodiment of the present application, the multiple cracks include at least one of the following: cracks extending along the stacking direction of the composite layers, with a depth equal to the stacking height of the composite layers; and cracks extending along the stacking direction of the composite layers, with a depth less than the stacking height of the composite layers.

[0013] The generation of cracks is due to the accumulation of internal stress in the multilayer film of the composite layer to a certain extent, and the substrate softens to a certain extent under the action of sputtering heat, resulting in stress release and cracking. Due to different degrees of stress release, the cracks may penetrate the composite layer or not, but both can significantly increase the resistivity of the multilayer film.

[0014] In the embodiment of the present application, the opening width of each crack is less than 2 μm.

[0015] Based on the mechanism of crack generation, the opening width of the crack is usually small, generally less than 2 microns; cracks with excessive width can easily cause tearing of the substrate or significantly affect the magnetic properties.

[0016] In the embodiment of the present application, the thickness of each magnetic layer is 5 nm-40 nm.

[0017] A magnetic layer that is too thick will cause columnar crystals to grow, resulting in excessively large grains and increased coercivity. It will also lead to the formation of a demagnetizing field within the magnetic layer. A thicker magnetic layer will also cause the layer to be divided into multiple magnetic domains. The domain walls will pin the motion of the magnetization vector, reducing the magnetic permeability and causing deterioration of high-frequency characteristics, thereby significantly reducing the magnetic permeability. A magnetic layer that is too thin will result in poor magnetic properties because a continuous magnetic film layer has not yet formed when the sputtering thickness is small. It may also be because the proportion of the magnetic layer in the total thickness is too low, resulting in a low saturation magnetization intensity, making it impossible to obtain a multilayer film with high magnetic permeability.

[0018] In the embodiment of the present application, the material of each magnetic layer is ferromagnetic metal or ferromagnetic alloy.

[0019] Ferromagnetic metals or ferromagnetic alloys generally have high saturation magnetization and low coercive force, and are more likely to obtain high magnetic permeability than other materials.

[0020] In the embodiment of the present application, the dielectric layer is made of at least one of insulating oxides, nitrides, and fluorides.

[0021] In the embodiment of the present application, a transition layer is formed between each adjacent magnetic layer and dielectric layer, and the thickness of the transition layer is less than or equal to 10 nm; the transition layer contains the magnetic material in the magnetic layer and the insulating material in the dielectric layer.

[0022] The transition layer serves as a buffer transition between the magnetic layer and the dielectric layer, thereby improving the bonding strength between the magnetic layer and the dielectric layer.

[0023] In the embodiment of the present application, the volume proportion of the magnetic material in the transition layer is between 20% and 80%.

[0024] In the embodiment of the present application, the total number of the multiple magnetic layers and the multiple dielectric layers is greater than 50, and the total thickness is greater than 300 nm.

[0025] If the combined thickness of the multiple magnetic layers and the multiple dielectric layers is too small, sufficient absorption performance will not be achieved (i.e., the product of the imaginary part of the magnetic permeability and the thickness will not be high enough). Furthermore, the accumulated stress in the thin film will not be sufficient to cause cracks. Experimental data shows that visible cracks in thin film materials need to be at least 300 nm thick, and cracks can only be stably formed at a thickness of 1 micron or more.

[0026] In the embodiment of the present application, the total thickness of the multiple magnetic layers and the multiple dielectric layers is 1 μm-10 μm.

[0027] The total thickness of the multiple magnetic layers and multiple dielectric layers does not exceed 10 microns at most, otherwise the internal stress will accumulate too much, which will easily cause the film layer adhesion to decrease and thus peel off. On the other hand, too large a thickness will take too long and have low commercial value.

[0028] In the embodiment of the present application, the substrate is flexible, has a thickness of 5 μm-50 μm, a glass transition temperature of 25° C.-100° C., and a melting point greater than 100° C.

[0029] In the embodiment of the present application, the material of the substrate is one of polyethylene terephthalate, polymethyl methacrylate, polybutadiene-styrene, polyphenylene sulfide, acrylonitrile-butadiene-styrene plastic, polyethylene terephthalate-1,4-cyclohexanedimethanol, and polystyrene.

[0030] The substrate has an impact on the generation of cracks. If the substrate is highly rigid, it is not conducive to the generation of cracks and will cause the film layer to break and fall off when a certain film thickness is reached. In the process of sputtering to form the multiple magnetic layers and the multiple dielectric layers, a certain amount of heat is generated and the temperature rises. Usually, the temperature does not exceed 100°C. Therefore, it is required to use a flexible polymer with a glass transition temperature of 25°C-100°C and a melting point greater than 100°C as the film-forming substrate. If the thickness of the flexible polymer substrate is too thin, especially when the thickness is less than 5μm, the process of crack formation will tear the polymer substrate; if the thickness of the flexible polymer substrate is too thick, especially when the thickness is greater than 50μm, it usually does not meet the application requirements for the thickness of the ultra-thin film layer.

[0031] In the embodiment of the present application, the substrate is a plastic packaging material layer with a thickness of 5 μm-500 μm.

[0032] The multiple magnetic layers and the multiple dielectric layers can be deposited on a plastic packaging material layer used to package electronic components, such as chips, to effectively absorb the internal crosstalk noise of the plastic packaging material layer.

[0033] A second aspect of an embodiment of the present application provides a semiconductor packaging module, comprising electronic components, the above-mentioned magnetic film attached to the electronic components, and a metal shielding layer attached to the magnetic film; the base layer of the magnetic film is a plastic packaging material layer.

[0034] The magnetic film absorbs the noise of mutual crosstalk inside the semiconductor packaging module, and the metal shielding layer is used to prevent electromagnetic waves in the semiconductor packaging module from radiating to the outside. The magnetic film and the metal shielding layer can effectively solve the noise interference problem of the semiconductor packaging module.

[0035] A third aspect of an embodiment of the present application provides an electronic device, comprising a circuit board and the semiconductor packaging module according to the second aspect located on the circuit board.

[0036] A fourth aspect of an embodiment of the present application provides an electronic device, comprising the semiconductor packaging module according to the second aspect, wherein a shell is located in the shell.

[0037] A fifth aspect of an embodiment of the present application provides an electronic device, comprising a noise source that radiates electromagnetic waves and the magnetic film described in the first aspect, wherein the magnetic film is attached to the noise source or arranged on a path where the noise source propagates noise.

[0038] The magnetic film is a wave-absorbing material with high magnetic permeability in the radio frequency microwave band, and can be arranged at a position where the electronic device needs to absorb electromagnetic waves to absorb excess electromagnetic waves.

[0039] In an embodiment of the present application, the electronic device includes a middle frame and a metal part made of metal material. The middle frame and the metal part cooperate to form a cavity. The noise source is arranged in the cavity. A signal transmitter is arranged outside the cavity. The magnetic film is located in the cavity.

[0040] The interference noise generated by the noise source usually propagates outward along the cavity between the middle frame and the metal part. Therefore, a magnetic film is set in the cavity. When the electromagnetic waves generated by the noise source pass through the magnetic film, they will be absorbed by the magnetic film and are difficult to transmit out of the cavity, thereby preventing the interference signal from affecting the signal transmitter.

[0041] A sixth aspect of the embodiments of the present application provides a method for preparing a magnetic thin film, comprising:

[0042] providing a substrate;

[0043] forming a composite layer on one side of the substrate by sputtering, wherein the composite layer includes a plurality of magnetic layers and a plurality of dielectric layers, wherein the plurality of magnetic layers and the plurality of dielectric layers are alternately arranged on one side of the substrate;

[0044] The thickness of each magnetic layer is 2nm-100nm; the thickness of each dielectric layer is 2nm-10nm; the thickness of the composite layer is 50nm-10μm;

[0045] During the process of sputtering to form the composite layer, the internal stress in the composite layer is released, resulting in the formation of multiple cracks in the composite layer that are non-periodically distributed, at least some of the multiple cracks have different extension directions along the cross-section perpendicular to the stacking direction of the composite layer, and at least some of the multiple cracks extend non-linearly along the cross-section perpendicular to the stacking direction of the composite layer.

[0046] Compared with existing patterning methods such as photolithography, the method for preparing the magnetic film of the present application has the advantages of being convenient and low-cost, and can adjust the magnetic permeability, magnetic resonance frequency and resistivity.

[0047] In the embodiment of the present application, each magnetic layer is sputtered by DC sputtering, the sputtering pressure is set to 0.1Pa-10.0Pa, the sputtering rate is set to 0.1nm / s-2nm / s, and the sputtering time of each layer is 5s-100s.

[0048] In the embodiment of the present application, each dielectric layer is sputtered by radio frequency sputtering, the sputtering pressure is set to 0.1Pa-10.0Pa, the sputtering rate is set to 0.05nm / s-0.1nm / s, and the sputtering time of each layer is 5s-500s.

[0049] In order for the film to accumulate sufficient internal stress to produce cracks during the sputtering process, the sputtering material should be sputtered at a high sputtering rate. A lower sputtering efficiency results in good film quality, insufficient internal stress accumulation, and difficulty in producing cracks. If the sputtering efficiency is too high, the multilayer structure is easily damaged or even powdered and detached. In addition, during magnetron sputtering, the sputtering gas pressure is crucial to the sputtering rate and film quality. If the sputtering gas pressure is too low, the target material will be difficult to ignite or the glow will be unstable, resulting in poor sputtering effect. If the sputtering gas pressure is too high, the sputtered target particles will have more chances of colliding with the gas, affecting the film adhesion and affecting the magnetic properties.

[0050] In an embodiment of the present application, the preparation method further includes forming a transition layer between each adjacent magnetic layer and dielectric layer, wherein the transition layer contains the magnetic material in the magnetic layer and the insulating material in the dielectric layer, and the thickness of the transition layer is less than or equal to 10 nm.

[0051] In the embodiment of the present application, the transition layer is co-sputtered by DC and RF, the sputtering pressure is set to 0.1Pa-10.0Pa, the sputtering rate ratio between DC and RF sputtering is adjusted between 0.2-5, and the sputtering time of each layer is less than or equal to 50s. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic cross-sectional view of the magnetic film of the first embodiment of the present application.

[0053] Figure 2 It is a schematic cross-sectional view of the magnetic film according to the second embodiment of the present application.

[0054] Figure 3A and Figure 3B It is an exploded schematic diagram and a cross-sectional schematic diagram of the electronic device according to an embodiment of the present application.

[0055] Figure 4 2 is a cross-sectional schematic diagram of a semiconductor packaging module according to an embodiment of the present application.

[0056] Figure 5 This is a flow chart of the method for preparing the magnetic film according to an embodiment of the present application.

[0057] Figure 6 This is a scanning electron microscope cross-sectional view of the magnetic thin film of Example 1.

[0058] Figure 7 This is the absorptivity curve of the magnetic film of Example 1.

[0059] Figure 8 This is the magnetic permeability spectrum of the magnetic film of Example 2.

[0060] Figure 9 This is the magnetic permeability spectrum of the magnetic film of Example 3.

[0061] Figure 10 This is a magnetostatic property curve of the magnetic film of Example 5.

[0062] Figure 11 This is the X-ray diffraction pattern of the magnetic thin film of Example 6.

[0063] Figure 12 This is a transmission microscope photograph of the magnetic thin film of Example 7.

[0064] Figure 13 This is a microscopic reflection photograph of the magnetic thin film of Example 8.

[0065] Description of main component symbols

[0066] Magnetic film 100, 200, 520

[0067] Base 10

[0068] Magnetic layer 20

[0069] Dielectric layer 30

[0070] Crack 31

[0071] Transition layer 40

[0072] Electronic equipment 300

[0073] Middle frame 310

[0074] Metal parts 330

[0075] Cavity 350

[0076] Connection line 305

[0077] Display 301

[0078] Antenna unit 302

[0079] Circuit board 303

[0080] Battery 304

[0081] Semiconductor packaging module 500

[0082] Electronic components 510

[0083] Metal shielding layer 530 DETAILED DESCRIPTION

[0084] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0085] In one type of absorber material, a magnetic absorber is filled into a polymer matrix to form a composite material. This composite material combines the high magnetic permeability and high magnetic loss of magnetic materials with the flexibility and easy processing of polymer composites, while also achieving high insulation properties. The magnetic absorber is typically a high-permeability magnetic micropowder. Depending on the frequency at which the absorber operates, these typically include ferrites (<100 MHz), soft magnetic alloys (100 MHz-3 GHz), and carbonyl iron powders (3-18 GHz). In wireless communication terminals, soft magnetic alloy powders are commonly used as magnetic absorbers, including FeNi alloys, FeSiAl alloys, and FeSi alloys. To improve magnetic permeability, the magnetic absorber is processed into flaky micropowders and oriented and filled as high as possible. The shape anisotropy of the magnetic absorber allows it to exceed the Snoek limit, achieving higher high-frequency magnetic permeability. Its orientation enhances the permeability-enhancing effect of the anisotropy. High filling allows for a higher magnetic content, increasing the material's saturation magnetization and, consequently, permeability. To achieve high resistivity even under high-fill conditions, the surface of the magnetic absorber is typically treated with an insulating treatment to achieve excellent insulation. Typically, these absorbers can achieve a real permeability of up to 250 at 10 MHz, with an imaginary permeability of around 20. The imaginary permeability peaks between 10 and 100 MHz, reaching approximately 60 to 80. As frequency increases, the permeability decreases rapidly, reaching only around 5 to 10 real part values ​​and imaginary part values ​​of approximately 10 to 20 at 1 GHz. Therefore, at high frequencies above 1 GHz, the permeability of absorbers is typically very limited.

[0086] The embodiments of the present application provide a magnetic film, which is a microwave absorbing material with high magnetic permeability in the radio frequency microwave band. The magnetic film still has high magnetic permeability and high resistivity when the thickness reaches the micrometer level.

[0087] See also Figure 1 The magnetic film 100 of the first embodiment of the present application includes a substrate 10 and a composite layer located on one side of the substrate 10. The composite layer includes a plurality of magnetic layers 20 and a plurality of dielectric layers 30 stacked on one surface of the substrate 10. Figure 1 The Z-axis represents the stacking direction of the composite layer, the Y-axis represents the direction perpendicular to the paper, and the X-axis and Y-axis together define the cross-sectional direction of the magnetic film 100. The multiple magnetic layers 20 and the multiple dielectric layers 30 are arranged alternately. The total thickness of the multiple magnetic layers 20 and the multiple dielectric layers 30 is 50 nm to 10 μm, that is, the thickness of the composite layer is 50 nm to 10 μm. Unless otherwise specified, the data ranges mentioned in this application are inclusive.

[0088] In this embodiment, the portion of the magnetic film 100 closest to the substrate 10 is a dielectric layer 30, but this is not limiting and may also be a magnetic layer 20. In this embodiment, the portion of the magnetic film 100 furthest from the substrate 10 is a magnetic layer 20, but this is not limiting. Preferably, the portion furthest from the substrate 10 is a dielectric layer 30.

[0089] The composite layer on the substrate 10 is formed with irregular patterns of multiple cracks 31, which can be clearly seen under a microscope. Figure 12 and Figure 13 The transmission microscope photograph and reflection microscope photograph shown are Figure 12 Irregular light stripes and Figure 13 The irregular dark stripes in the figure are all cracks 31. Figure 12 and Figure 13 The microscope photographs are all taken in a cross-sectional direction perpendicular to the stacking direction of the composite layer, i.e., in the surface direction defined by the X-axis and Y-axis. It can be seen that the irregularity of the plurality of cracks 31 refers to the non-periodic distribution of the plurality of cracks 31. At least some of the plurality of cracks 31 extend in different directions perpendicular to the cross-sectional direction, and at least some of the plurality of cracks 31 extend in a non-linear direction along the cross-sectional direction.

[0090] The cracks 31 are formed when the internal stress in the composite layer is released during the sputtering process, causing the film to crack. The magnetic film 100 is prepared by magnetron sputtering. On the substrate 10, alternating magnetic layers 20 and dielectric layers 30 are formed by sputtering in a DC sputtering mode and an RF sputtering mode. Due to the mismatch between the mechanical and thermal properties of the magnetic layer 20 and the dielectric layer 30 and the substrate 10, as the film defects accumulate and the internal stress continues to increase during the sputtering process, it reaches a release level, resulting in the generation of film cracks 31, which expand to form continuous cracks 31, obtaining a film material with a crack 31 structure, thereby achieving high magnetic permeability while achieving low electrical conductivity. The multiple cracks 31 divide the continuous composite layer into several small areas, thereby significantly improving the overall resistivity of the magnetic film 100. For example, a region can be a region surrounded by three or more cracks 31. In some embodiments, the area of ​​each region along the above-mentioned cross-sectional direction is approximately 0.001mm 2 -0.3mm 2 For example, if no cracks are formed in the magnetic film 100 , the resistivity is about 0.01 μΩm. However, in the present application, the resistivity of the entire magnetic film 100 with the cracks 31 is 0.2 μΩm-20000 μΩm.

[0091] On the other hand, by controlling the sputtering conditions, the composition, thickness, film density, crystal orientation, grain size, internal stress, etc. of the magnetic layer 20 and the dielectric layer 30 can be regulated, and the resonant frequency can be adjusted to obtain high magnetic permeability in different frequency ranges.

[0092] After adjacent magnetic layers 20 are separated by a dielectric layer 30 of nanometer-scale thickness, the nanocrystalline effect of the single-layer magnetic layer 20 material, the high proportion of interface atoms and other characteristics can be maintained to the maximum extent, and the magnetic anisotropy caused by the shape of the nanometer-thick magnetic layer 20 can be maintained, thereby still having the characteristics of high magnetic permeability.

[0093] The composition of the magnetic layer 20 can be a ferromagnetic metal or a ferromagnetic alloy, such as Fe, Co, Ni, FeSiAl alloy, FeNi alloy, FeCo alloy, FeCoNi alloy, FeCr alloy, FeCoCr alloy, and FeB alloy. The selection of magnetic components usually considers materials with a large saturation magnetization, which is very critical for improving magnetic permeability; in addition, the main consideration is that the magnetic resonance frequency is close to the operating frequency of the absorbing film material. Therefore, the selection of the composition of the above-mentioned magnetic layer 20 covers common materials used for GHz operating frequencies, but is not limited to the above-mentioned material selection. Magnetic alloy materials generally have high saturation magnetization and low coercive force, and are easier to obtain high magnetic permeability than other materials. Preferably, the composition of each magnetic layer 20 is a magnetic alloy, and the magnetic alloy includes one or more magnetic alloys such as FeNi alloy, FeSiAl alloy, and FeCo alloy.

[0094] The thickness of each magnetic layer 20 is nanometer-scale, preferably 2nm-100nm, and more preferably 5nm-40nm. A magnetic layer 20 that is too thick will cause the growth of columnar crystals, resulting in excessively large grains and increased coercivity; it will also cause a demagnetization field to form within the magnetic layer 20; a thicker magnetic layer 20 will also cause the layer to be divided into multiple magnetic domains. The domain walls will pin the movement of the magnetization vector, reducing the magnetic permeability and causing deterioration of high-frequency characteristics, thereby significantly reducing the magnetic permeability. A magnetic layer 20 that is too thin will result in poor magnetic properties because a continuous magnetic film layer has not yet been formed when the sputtering thickness is small; it may also be because the proportion of the magnetic layer 20 in the total thickness is too low, resulting in a low saturation magnetization intensity, making it impossible to obtain a multilayer film with high magnetic permeability.

[0095] The dielectric layer 30 is made of at least one of insulating oxides, nitrides, and fluorides, preferably at least one of silicon dioxide, aluminum oxide, magnesium oxide, aluminum nitride, silicon nitride, magnesium fluoride, and calcium fluoride.

[0096] The thickness of each dielectric layer 30 is 2nm-10nm. The dielectric layer 30 separates the adjacent magnetic layers 20 into film layers with a thickness of nanometer level, which is the guarantee for obtaining high magnetic properties. Therefore, it needs to have a certain thickness to form a basically continuous film layer. The dielectric layer 30 also has the function of regulating the internal stress of the entire film. If the thickness of the dielectric layer 30 is too thin and the sputtering time is too short, on the one hand, the dielectric layer 30 will not have enough time to grow into a continuous film layer, resulting in an increase in defects and an increase in internal stress. In addition, the dielectric layer 30 can also be used to regulate the magnetic interaction between adjacent nanomagnetic layers 20. The adjacent magnetic layers 20 can form a magnetic exchange magnetic coupling effect through the non-magnetic layer 20 to improve ferromagnetism. Therefore, the thickness of each dielectric layer 30 is generally within 10nm, with a reference to not exceeding the magnetic exchange effect length of the magnetic layer 20 material. If the thickness of the dielectric layer 30 is too thick, it will also lead to an increase in time cost due to the relatively low sputtering efficiency of the non-magnetic layer 20.

[0097] The total number of the multiple magnetic layers 20 and the multiple dielectric layers 30 is greater than 50, and the total thickness is greater than 300 nm, preferably 1 μm to 10 μm. If the thickness of the composite layer is too small, on the one hand, it will not produce sufficient absorption performance, that is, the product of the imaginary part of the magnetic permeability and the thickness will not be high enough; on the other hand, when the thickness is small, the accumulated stress of the multilayer film will not be enough to cause cracks 31 in the film. Experimental data shows that the film material needs to be at least 300 nm to produce obvious cracks 31, and cracks 31 can only be generated more stably when it is above 1 micron. The maximum thickness of the film should not exceed 10 microns. Otherwise, the internal stress accumulation will be too large, which will easily reduce the adhesion of the film layer and cause it to peel off. On the other hand, if the thickness is too large, it will take too long and have low commercial value.

[0098] The crack 31 includes at least one of a through-type and a semi-through-type. The through-type is: along the stacking direction of the layers of the composite layer (the thickness direction of the composite layer), the extension depth of the crack 31 is equal to the thickness of the composite layer, that is, the crack 31 penetrates the composite layer. The semi-through-type is: along the stacking direction of the layers of the composite layer (the thickness direction of the composite layer), the extension depth of the crack 31 is less than the thickness of the composite layer, that is, the crack 31 does not penetrate the composite layer, for example, it only penetrates part of the magnetic layer 20 and part of the dielectric layer 30. The generation of the crack 31 is due to the fact that after the internal stress of the multilayer film of the composite layer accumulates to a certain extent, the polymer matrix softens to a certain extent under the action of sputtering heat, and the stress is released, causing cracking. Due to the different degrees of stress release, the lines formed by the cracks may be through-type or semi-through-type, but both can significantly increase the resistivity of the multilayer film. Based on the mechanism of the crack 31 , the opening width of the crack 31 is usually small, generally less than 2 μm; a crack 31 with an excessively large opening can easily cause tearing of the polymer substrate or significantly affect the magnetic properties.

[0099] In the present application, the substrate 10 is a flexible substrate with a thickness of 5μm-50μm, a glass transition temperature of 25℃-100℃, and a melting point greater than 100℃. The flexible substrate is a polymer material. Preferably, the material of the flexible substrate can be one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polybutadiene-styrene (PBS), polyphenylene sulfide (PPS), acrylonitrile-butadiene-styrene plastic (ABS), polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), and polystyrene (PS). The substrate 10 has an impact on the generation of cracks 31. If it is a substrate with strong rigidity, it is not conducive to the generation of cracks 31, and will cause the film layer to break and fall off when a certain film thickness is reached. The sputtering process of forming the multiple magnetic layers 20 and the multiple dielectric layers 30 generates a certain amount of heat, resulting in a temperature rise, typically not exceeding 100°C. Therefore, a flexible polymer substrate with a glass transition temperature between 25°C and 100°C and a melting point greater than 100°C is required. If the flexible polymer substrate is too thin, particularly if the thickness is less than 5μm, the cracks 31 may tear the polymer substrate. If the flexible polymer substrate is too thick, particularly if the thickness is greater than 50μm, the ultra-thin film thickness requirement is generally not met.

[0100] See also Figure 2 The magnetic film 200 of the second embodiment of the present application is substantially similar to the magnetic film 100 of the first embodiment and also includes a substrate 10 and a composite layer stacked on the substrate 10. The composite layer includes multiple magnetic layers 20 and multiple dielectric layers 30, and the multiple magnetic layers 20 and the multiple dielectric layers 30 are arranged alternately. The difference is that the composite layer also includes multiple transition layers 40, with a transition layer 40 formed between each adjacent pair of magnetic layers 20 and dielectric layers 30. In one embodiment of the present application, the dielectric layers 30, transition layers 40, magnetic layers 20, and transition layers 40 are sequentially stacked on the substrate 10 in this order.

[0101] In this embodiment, the dielectric layer 30 is closest to the substrate 10 in the magnetic film 200, but this is not limited to this and may also be a magnetic layer 20. In this embodiment, the dielectric layer 30 is furthest from the substrate 10 in the magnetic film 100, but this is not limited to this. Preferably, the magnetic layer 20 is furthest from the substrate 10.

[0102] The transition layer 40 contains the magnetic material of the magnetic layer 20 and the insulating material of the dielectric layer 30. The thickness of the transition layer 40 is less than or equal to 10 nm. The transition layer 40 acts as a buffer transition between the magnetic layer 20 and the dielectric layer 30, thereby improving the bonding strength between the magnetic layer 20 and the dielectric layer 30.

[0103] The total number of the multiple magnetic layers 20 , the multiple transition layers 40 , and the multiple dielectric layers 30 is greater than 50, and the total thickness is greater than 300 nm, preferably 1 μm-10 μm.

[0104] Controlling the internal stress of multilayer thin film materials is key to achieving magnetic properties and the formation of cracks 31. The transition layer 40 can also regulate internal stress and minimize its impact on magnetic properties. Because the dielectric layer 30 is sputtered using radio frequency (RF) technology, it typically exhibits a dense film with low internal stress, in stark contrast to the DC-sputtered magnetic layer 20, which exhibits numerous defects and high internal stress. Therefore, the sputtering of the dielectric layer 30 material can regulate the overall internal stress and defect levels of the multilayer film. Internal stress is closely related to magnetic properties and is also the source of the crack 31 structure in the multilayer film. The transition layer 40 is co-sputtered from the magnetic layer 20 material and the dielectric layer material. The volume fraction of the magnetic material ranges from 20% to 80%, preferably between 50% and 80%. Compared to a pure dielectric layer 30, this reduces the weakening of the magnetic exchange interaction and further regulates the stress of the multilayer film. However, the thickness should not exceed 10 nm to avoid significantly affecting the magnetic properties. For applications with appropriate internal stress levels, the addition of a transition layer is unnecessary. According to the function of the transition layer 40 , the sputtering is not limited to the co-sputtering of the material of the magnetic layer 20 and the material of the dielectric layer 30 , but may also be independent sputtering of a third target material.

[0105] The present application also provides an electronic device utilizing the aforementioned magnetic film 100 or 200. The magnetic film 100 or 200 is an absorbing material with high magnetic permeability in the radio frequency microwave band and can be positioned at a location within the electronic device 300 where electromagnetic waves need to be absorbed, effectively absorbing the electromagnetic waves and preventing interference noise. The magnetic film 100 or 200 can be directly attached to a noise source (not shown, such as a noise-generating circuit, chip, module, high-speed signal line, etc.) that radiates electromagnetic wave noise, or can be positioned along the path from the noise source to a noise receptor (not shown).

[0106] Figure 3A and Figure 3B The internal environment of the electronic device 300 provided in this application is exemplified, and the electronic device 300 is described as a mobile phone. Figure 3A As shown, the electronic device 300 includes: a display screen 301, a middle frame 310, and a circuit board 303 stacked in sequence. Figure 3A and Figure 3B Only some components of the electronic device 300 are schematically shown, and the actual shape, actual size and actual structure of these components are not affected by the present invention. Figure 3A and Figure 3B limited.

[0107] like Figure 3BAs shown, a layered metal member 330 is provided on the surface of the display screen 301 near the middle frame 310. The metal member 330 can prevent the imaging unit in the display screen 301 from being interfered with by electromagnetic signals, and can also provide good heat dissipation for the display screen 301. Optionally, the display screen 301 can be a liquid crystal display (LCD), a light emitting diode (LED), or an organic light-emitting semiconductor (OLED), etc., which is not limited in this application.

[0108] The middle frame 310 is made of metal and mainly supports the entire device. Figure 3B As shown, the metal part 330 of the display screen 301 cooperates with the middle frame 310 to form a cavity 350. The cavity 350 has a metal wall (or metal frame). In this embodiment, the cavity 350 is a non-completely enclosed cavity.

[0109] like Figure 3B As shown, to enable electrical signal transmission between display screen 301 and electronic components (e.g., a processor) on circuit board 303, electronic device 300 is provided with a connecting line 305. Connecting line 305 passes through cavity 350 to electrically connect display screen 301 and circuit board 303. Specifically, one end of connecting line 305 is electrically connected to display screen 301, while the other end extends through midframe 310 to electrically connect to circuit board 303. Connecting line 305 can be a Mobile Industry Processor Interface (MIPI) or a flexible printed circuit board.

[0110] like Figure 3B As shown, the electronic device 300 may further include a battery 304. In this embodiment, the battery 304 and the circuit board 303 are both located on the same side of the middle frame 310 and are arranged adjacent to each other. A metal layer (not shown) may also be provided inside or on the surface of the battery 304.

[0111] like Figure 3B As shown, the electronic device 300 may further include a signal transmitter. In this embodiment, the signal transmitter is an antenna unit 302 for wireless communication, but the present invention is not limited thereto. In one implementation, the antenna unit 302 may be disposed on one or more sides outside the cavity 350. The antenna unit 302 may be a frame antenna, a flexible printed circuit (FPC) antenna, or other types of antennas.

[0112] The components (electronic components) in the electronic device 300 often generate electromagnetic waves when powered on. These electromagnetic waves will interfere with the antenna unit 302, so these components are interference sources / noise sources of the antenna unit 302. For example, the connecting line 305 of this embodiment will generate interference signals as an interference source when transmitting electrical signals. Because the cavity 350 is a metal wall (such as the metal part 330, the middle frame 310 and the side frame), the interference signal cannot penetrate the metal wall and can only be transmitted inside the cavity 350. The direction of the arrow shown in Figure 3 represents the propagation direction of the interference signal. The interference signal is transmitted through the cavity 350 to the antenna unit 302 located at the opening of the cavity 350, which will affect the performance of the antenna unit 302. In order to reduce the impact of the interference source on the antenna unit 302 and other devices, an existing method is to add a shielding cover at the interference source. However, for this connecting line 305 as an interference source, it is difficult to achieve shielding with a shielding cover.

[0113] like Figure 3B As shown, a magnetic film 100 or a magnetic film 200 is provided in the cavity 350. In this embodiment, the magnetic film 100 or the magnetic film 200 is provided on the middle frame 310. When the electromagnetic wave generated by the noise source (connecting line 305) passes through the magnetic film 100 or 200, it will be absorbed by the magnetic film 100 or 200 and is difficult to be transmitted out of the cavity 350, thereby avoiding the interference signal from affecting the antenna unit 302.

[0114] See also Figure 4 The present application also provides a semiconductor packaging module 500, comprising an electronic component 510, a magnetic film 520 attached to the electronic component 510, and a metal shielding layer 530 attached to the magnetic film 520. The structure of the magnetic film 520 is substantially the same as that of the magnetic film 100 and the magnetic film 200 described above, with the only difference being that the base layer of the magnetic film 520 is different, which is a plastic encapsulation material layer with a thickness of 5 μm-500 μm. The plastic encapsulation material layer contains a polymer resin, an inorganic filler (e.g., silica), and other functional components. That is, the alternating arrangement of multiple magnetic layers and the multiple dielectric layers is directly deposited on the plastic encapsulation material layer. The plastic encapsulation material layer is used to both encapsulate the electronic component 510 and serve as a base for the magnetic film 520. The electronic component 510 may be an integrated circuit, a device of an integrated circuit, or a chip (e.g., a chip in a system-level package). The magnetic film 520 absorbs the noise of mutual crosstalk inside the semiconductor packaging module 500, and the metal shielding layer 530 is used to prevent the electromagnetic waves in the semiconductor packaging module 500 from radiating to the outside. The magnetic film 520 and the metal shielding layer 530 can effectively solve the noise interference problem of the semiconductor packaging module 500.

[0115] It is understandable that a bonding layer (not shown) may be selectively provided between the composite laminate of the alternating arrangement of multiple magnetic layers and multiple dielectric layers and the substrate (molding material layer) to improve the connection strength between the two.

[0116] It is understandable that since the material of the metal shielding layer 530 is prone to oxidation, the metal shielding layer 530 may be coated with a protective layer (not shown) to prevent the metal shielding layer 530 from oxidation.

[0117] The present application also provides an electronic device (not shown) comprising the aforementioned semiconductor package module 500. For example, the electronic device further comprises a housing, wherein the semiconductor package module 500 is located within the housing. Alternatively, the electronic device comprises a circuit board, wherein the semiconductor package module 500 is disposed on the circuit board.

[0118] See also Figure 5 , the present application also provides a method for preparing a magnetic film, comprising:

[0119] providing a substrate;

[0120] forming a composite layer on one surface of the substrate, the composite layer comprising a plurality of magnetic layers and a plurality of dielectric layers, the plurality of magnetic layers and the plurality of dielectric layers being arranged alternately, i.e., the magnetic layers and the dielectric layers are sputtered alternately and cyclically; the thickness of each magnetic layer is 2 nm to 100 nm; the thickness of each dielectric layer is 2 nm to 10 nm; and the total thickness of the plurality of magnetic layers and the plurality of dielectric layers is 50 nm to 10 μm;

[0121] During the process of forming the composite layer by sputtering, the internal stress in the composite layer is released, resulting in the formation of non-periodically distributed cracks in the composite layer.

[0122] The substrate can be selected to have a thickness of 5μm-50μm, a glass transition temperature of 25°C-100°C, and a melting point greater than 100°C. The substrate is a polymer material. Preferably, the material of the substrate can be one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polybutadiene-styrene (PBS), polyphenylene sulfide (PPS), acrylonitrile-butadiene-styrene plastic (ABS), polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), and polystyrene (PS). The substrate can also be a plastic encapsulation material layer. Before sputtering, the substrate needs to be cleaned to remove impurities and dirt on its surface.

[0123] The magnetic layer is composed of ferromagnetic metal or ferromagnetic alloy, such as Fe, Co, Ni, FeSiAl alloy, FeNi alloy, FeCo alloy, FeCoNi alloy, FeCr alloy, FeCoCr alloy, or FeB alloy.

[0124] The dielectric layer is composed of at least one of insulating oxides, nitrides, and fluorides, preferably at least one of silicon dioxide, aluminum oxide, magnesium oxide, aluminum nitride, silicon nitride, magnesium fluoride, and calcium fluoride.

[0125] Sputtering uses magnetron sputtering coating equipment with DC and RF multi-target sputtering functions, automatic program control and reciprocating multi-layer sputtering functions as the preparation equipment.

[0126] Each magnetic layer is sputtered using DC sputtering, with the sputtering gas pressure set at 0.1Pa-10Pa, the sputtering power and target-substrate distance adjusted to make the sputtering rate reach 0.1nm / s-2nm / s, and the sputtering time for each layer is 5s-100s.

[0127] Each dielectric layer is sputtered by radio frequency sputtering, with the sputtering gas pressure set at 0.1Pa-10Pa, the sputtering power and the target-substrate distance adjusted to make the sputtering rate reach 0.05nm / s-0.1nm / s, and the sputtering time for each layer is 5s-500s.

[0128] The preparation method also includes forming a transition layer between each adjacent magnetic layer and dielectric layer. The transition layer comprises the ferromagnetic metal or ferromagnetic alloy in the magnetic layer and the insulating material in the dielectric layer. For example, sputtering is performed alternately in a sequence of dielectric layer, transition layer, magnetic layer, and transition layer until the number of layers and thickness reach a predetermined value. The thickness of the transition layer is 10 nm or less. The volume percentage of the magnetic alloy material in the transition layer is between 20% and 80%, preferably between 50% and 80%.

[0129] The transition layer is co-sputtered by DC and RF, the sputtering pressure is set to 0.2Pa-2.0Pa, the sputtering rate ratio between DC and RF sputtering is adjusted between 0.2-5, and the sputtering time of each layer is less than or equal to 50s.

[0130] In addition, in order for the film to accumulate enough internal stress to produce cracks during the sputtering process, the sputtering material should be sputtered at a higher sputtering rate; a lower sputtering efficiency leads to better film quality, insufficient internal stress accumulation, and difficulty in producing cracks; if the sputtering efficiency is too high, the multi-layer structure is easily damaged or even powdered and falls off.

[0131] Furthermore, during magnetron sputtering, the sputtering gas pressure is crucial to the sputtering rate and film quality. If the sputtering pressure is too low, the target will have difficulty igniting or the glow will be unstable, resulting in poor sputtering results. If the sputtering pressure is too high, the chances of sputtered target particles colliding with the gas increase, affecting film adhesion and compromising magnetic properties.

[0132] The present application has the following advantages and beneficial effects: The magnetic film of the present application has a high magnetic permeability, 10-30 times higher than that of traditional absorbing materials, reaching 200-600. Compared to magnetic films prepared by other processes, its resistivity is 10-1000 times higher, significantly increasing the skin depth and improving the impedance matching to electromagnetic waves. Furthermore, the high magnetic permeability can be maintained even at micron-level thicknesses. As a result, the magnetic film of the present application exhibits excellent microwave absorption performance while maintaining an extremely thin thickness, requiring only less than 1 / 10 the thickness of traditional absorbing materials to achieve comparable or even better absorption performance, breaking through the thickness and performance bottlenecks of existing absorbing materials. It also overcomes the bottleneck of magnetic film materials, which suffer from poor impedance matching and weak absorption performance due to high conductivity. As an absorbing material, the magnetic film of the present application has broad application prospects in electronic components, wireless communications, radar absorbing and stealth, and is particularly suitable for electromagnetic interference prevention and control in extremely thin and wearable applications.

[0133] Compared with existing patterning methods such as photolithography, the method for preparing the magnetic film of the present application has the advantages of being convenient and low-cost, and can adjust the magnetic permeability, magnetic resonance frequency and resistivity.

[0134] The technical solutions of the embodiments of the present application are further described below through specific examples.

[0135] Example 1

[0136] A 20 μm thick PET (Polyethylene terephthalate) substrate, which had been cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 Pa, the process parameters were set as follows: argon flow rate of 40sccm, sputtering pressure of 0.15Pa, tray speed of 20r / min, FeSiAl using DC sputtering with a sputtering efficiency of 0.5nm / s, and SiO2 using RF sputtering with a sputtering efficiency of 0.05nm / s. The FeSiAl magnetic alloy layer, co-sputtering transition layer, SiO2 dielectric layer, and co-sputtering layer were sputtered alternately in this order. The thickness of each FeSiAl magnetic alloy layer was 6nm, the thickness of each SiO2 dielectric layer was 2nm, and the thickness of each co-sputtering transition layer was 5nm. After 100 sputtering cycles, the sputtering ended, and a FeSiAl / SiO2 multilayer magnetic film sample was obtained. Scanning electron microscopy characterization results showed that the sample had a total thickness of 1.8μm and had a good layered structure. The single-port short-circuit waveguide method was used to test its magnetic permeability, and the imaginary part of the magnetic permeability reached 250 at 1.5GHz. The four-probe resistance meter was used to test its square resistance and calculated its conductivity to be 5×10 6 S / m.

[0137] Figure 6 This is a cross-sectional view of a sample of the magnetic thin film of Example 1, taken by scanning electron microscopy. Figure 7 The magnetic film obtained in Example 1 was subjected to a microstrip line test to obtain an absorptivity curve. It can be seen that the magnetic film in Example 1 has an absorptivity of more than 90% for electromagnetic waves at 1-2 GHz, showing excellent microwave absorption performance.

[0138] Example 2

[0139] The 20 μm thick PET substrate, which was cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 When the sputtering pressure is 0.2 Pa, the process parameters are set as follows: argon flow rate is 40sccm, sputtering pressure is 0.2Pa, tray speed is 20r / min, FeNi adopts DC sputtering, sputtering efficiency is 0.3nm / s, SiO2 adopts RF sputtering, sputtering efficiency is 0.05nm / s. The FeNi magnetic alloy layer and SiO2 dielectric layer are sputtered alternately in the order of FeNi magnetic alloy layer and SiO2 dielectric layer. The thickness of each FeNi magnetic alloy layer is 5nm, and the thickness of each SiO2 dielectric layer is 2nm. After 100 sputtering cycles, the sputtering ends and the FeNi / SiO2 multilayer magnetic film sample is obtained. The scanning electron microscopy characterization results show that the total thickness of the sample is 0.7μm and it has a good layered structure. The square resistance is tested by a four-probe resistance meter and its conductivity is calculated to be 3×10 5 S / m.

[0140] The magnetic film of Example 2 was tested using a single-port short-circuit waveguide method. Figure 8 As shown in FIG. 2 , the imaginary part of the magnetic permeability of the magnetic film of Example 2 reaches 270 at 0.6 GHz.

[0141] Example 3

[0142] The 20 μm thick PET substrate, which was cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4Pa, set the process parameters as follows: argon flow rate of 40sccm, sputtering pressure of 0.2Pa, tray speed of 20r / min, FeNi using DC sputtering, sputtering efficiency of 0.3nm / s, SiO2 using RF sputtering, sputtering efficiency of 0.05nm / s. Sputtering is carried out alternately in the order of FeNi magnetic alloy layer and SiO2 dielectric layer. The thickness of each FeNi magnetic alloy layer is 15nm, and the thickness of each SiO2 dielectric layer is 2nm. After 40 sputtering cycles, the sputtering ends and a FeNi / SiO2 multilayer magnetic film sample is obtained. Scanning electron microscopy characterization results show that the total thickness of the sample is 0.7μm and it has a good layered structure. The square resistance is tested using a four-probe resistance meter and its conductivity is calculated to be 1.4×10 5 S / m.

[0143] The magnetic film of Example 3 was tested using a single-port short-circuit waveguide method. Figure 9 As shown, the imaginary part of the magnetic permeability of the magnetic film of Example 3 reaches 630 at 0.7 GHz.

[0144] Example 4

[0145] The 20 μm thick PET substrate, which was cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 When the sputtering pressure was 0.2 Pa, the process parameters were set as follows: argon flow rate of 40 sccm, sputtering pressure of 0.2 Pa, tray speed of 20 r / min, DC sputtering of FeNi with a sputtering efficiency of 0.3 nm / s, and RF sputtering of SiO2 with a sputtering efficiency of 0.05 nm / s. FeNi magnetic alloy layers and SiO2 dielectric layers were alternately sputtered in this order. The thickness of each FeNi magnetic alloy layer was 15 nm, and the thickness of each SiO2 dielectric layer was 2.5 nm. Sputtering ended after 70 cycles, resulting in a FeNi / SiO2 multilayer magnetic film sample.

[0146] Scanning electron microscopy results show that the sample has a total thickness of 1.2 μm and a good layered structure. The permeability is measured by a single-port short-circuit waveguide method, and the imaginary part of the permeability reaches 180 at 1.2 GHz. The square resistance is measured by a four-probe resistance meter, and the conductivity is calculated to be 3×10 5 S / m, with semi-through texture.

[0147] Example 5

[0148] The 20 μm thick PET substrate, which was cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4Pa, the process parameters are set as follows: argon flow rate of 40sccm, sputtering pressure of 0.2Pa, tray speed of 20r / min, FeNi using DC sputtering, sputtering efficiency of 0.3nm / s, SiO2 using RF sputtering, sputtering efficiency of 0.05nm / s. The FeNi magnetic alloy layer and SiO2 dielectric layer are sputtered alternately in the order of FeNi magnetic alloy layer and SiO2 dielectric layer. The thickness of each FeNi magnetic alloy layer is 15nm, and the thickness of each SiO2 dielectric layer is 3nm. After 70 sputtering cycles, the sputtering ends and the FeNi / SiO2 multilayer magnetic film sample is obtained. The scanning electron microscopy characterization results show that the total thickness of the sample is 1.1μm and it has a good layered structure. The single-port short-circuit waveguide method is used to test its magnetic permeability. The imaginary part of the magnetic permeability reaches 307 at 0.7GHz. The four-probe resistance meter is used to test its square resistance and its conductivity is calculated to be 3×10 6 S / m.

[0149] The magnetic film of Example 5 was tested using a vibrating sample magnetometer. Figure 10 The static magnetic property curve shown in the figure shows that its coercivity is only 0.6 Oe, which shows excellent magnetic properties.

[0150] Example 6

[0151] The 12.5 μm thick PET substrate, which had been cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 Pa, the process parameters were set as follows: argon flow rate of 40 sccm, sputtering pressure of 0.35 Pa, tray rotation speed of 20 rpm, direct current sputtering of FeNi with a sputtering efficiency of 0.3 nm / s, and radio frequency sputtering of SiO2 with a sputtering efficiency of 0.05 nm / s. FeNi magnetic alloy layers and SiO2 dielectric layers were sputtered alternately, with each FeNi magnetic alloy layer having a thickness of 15 nm and each SiO2 dielectric layer having a thickness of 3 nm. Sputtering was terminated after 120 sputtering cycles, resulting in a FeNi / SiO2 multilayer magnetic film sample. Scanning electron microscopy results showed that the sample had a total thickness of 2.1 μm and exhibited a well-defined layered structure. The imaginary part of the magnetic permeability reached 215 at 1.05 GHz using the single-port short-circuit waveguide method. The square resistance of the sample was measured using a four-probe resistance meter, and the conductivity was calculated to be 500 S / m, indicating a through-crack structure.

[0152] Figure 11 The XRD (X-ray diffraction) pattern of the sample of the magnetic film of Example 6 shows characteristic peaks of the substrate PET and the magnetic alloy layer FeNi3. The average grain size was calculated to be 5 nm based on the XRD diffraction pattern.

[0153] Example 7

[0154] The 12.5 μm thick PET substrate, which had been cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 Pa, the process parameters were set as follows: argon flow rate of 40 sccm, sputtering pressure of 0.35 Pa, tray rotation speed of 20 rpm, direct current sputtering of FeNi with a sputtering efficiency of 0.42 nm / s, and radio frequency sputtering of SiO2 with a sputtering efficiency of 0.063 nm / s. FeNi magnetic alloy layers and SiO2 dielectric layers were sputtered alternately, with each FeNi magnetic alloy layer having a thickness of 15 nm and each SiO2 dielectric layer having a thickness of 3 nm. Sputtering was terminated after 120 cycles, resulting in a FeNi / SiO2 multilayer magnetic film sample. Scanning electron microscopy results indicate that the sample has a total thickness of 2.1 μm and a well-defined layered structure. The imaginary part of the magnetic permeability reached 350 at 1.35 GHz using the single-port short-circuit waveguide method. The sheet resistance was measured using a four-probe resistance meter, and the conductivity was calculated to be 50 S / m.

[0155] Figure 12 This is a transmission microscope photograph of a sample of the magnetic film of Example 7. Figure 12 Through-type cracks can be seen, and the cracks are surrounded by irregular polygonal units. The area of ​​the polygonal units is 0.001mm. 2 -0.3mm 2 .

[0156] Example 8

[0157] The 12.5 μm thick PET substrate, which had been cleaned and dried with anhydrous ethanol, was fixed on the magnetron sputtering sample tray and vacuumed. When the background vacuum of the magnetron sputtering chamber reached 10 -4 Pa, the process parameters were as follows: argon flow rate of 40 sccm, sputtering pressure of 0.35 Pa, tray speed of 20 rpm, direct current sputtering of FeNi with a sputtering efficiency of 0.42 nm / s, and radio frequency sputtering of SiO2 with a sputtering efficiency of 0.063 nm / s. Sputtering was performed alternately in the order of FeNi magnetic alloy layer, co-sputtered transition layer, SiO2 dielectric layer, and co-sputtered transition layer. The thickness of each FeNi magnetic alloy layer was 9.5 nm, each co-sputtered transition layer was 3.5 nm, and each SiO2 dielectric layer was 2 nm. Sputtering was terminated after 120 cycles, resulting in a FeNi / SiO2 multilayer magnetic film sample. Scanning electron microscopy results showed that the sample had a total thickness of 2.1 μm and exhibited a well-defined layered structure. The imaginary part of the magnetic permeability reached 290 at 1.28 GHz using the single-port short-circuit waveguide method. The sheet resistance was measured using a four-probe resistance meter, and the conductivity was calculated to be 1000 S / m.

[0158] Figure 13 This is a microscopic reflection photograph of a sample of the magnetic film of Example 8. Figure 13 Through-type cracks can be seen. The cracks are irregular polygons with a width of about 0.1 μm.

[0159] Example 9

[0160] Fix the plastic-sealed chip module on the magnetron sputtering sample tray, evacuate the chamber, and wait until the background vacuum of the magnetron sputtering chamber reaches 10 -4 When the chip module is sputtered at 1.5 Pa, a bonding layer is first sputtered on the surface of the chip module's plastic encapsulation material layer. The process parameters are then set: an argon flow rate of 40 sccm, a sputtering pressure of 0.35 Pa, a tray speed of 20 r / min, direct current sputtering for FeNi with a sputtering efficiency of 0.42 nm / s, and radio frequency sputtering for SiO2 with a sputtering efficiency of 0.063 nm / s. Sputtering is performed alternately in the order of FeNi magnetic alloy layer, co-sputtered transition layer, SiO2 dielectric layer, and co-sputtered transition layer. Each FeNi magnetic alloy layer has a thickness of 9.5 nm, each co-sputtered transition layer has a thickness of 3.5 nm, and each SiO2 dielectric layer has a thickness of 2 nm. After 120 sputtering cycles, a soft magnetic film layer is grown on the bonding layer surface, resulting in an FeNi / SiO2 multilayer magnetic film. A metal shielding layer and protective layer are then sputtered on the surface of the FeNi / SiO2 multilayer magnetic film.

[0161] It should be noted that the above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application; the embodiments of the present application and the features of the embodiments can be combined with each other unless there is a conflict. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

Claims

1. A magnetic film, characterized in that include: substrate; a composite layer located on one side of the substrate, the composite layer comprising a plurality of stacked magnetic layers and a plurality of dielectric layers, the plurality of magnetic layers and the plurality of dielectric layers being alternately arranged on one side of the substrate; Each magnetic layer has a thickness of 2nm-100nm; each dielectric layer has a thickness of 2nm-10nm; the composite layer has a thickness of 50nm-10µm; the composite layer includes a plurality of cracks, the plurality of cracks are non-periodically distributed, at least some of the plurality of cracks extend in different directions along a cross section perpendicular to the stacking direction of the composite layer, and at least some of the plurality of cracks extend non-linearly along a cross section perpendicular to the stacking direction of the composite layer; The multiple cracks are caused by the release of internal stress in the composite layer during the process of forming the composite layer by sputtering.

2. The magnetic film according to claim 1, wherein The cracks divide the composite layer into several regions.

3. The magnetic film according to claim 2, wherein The area of ​​each region along the cross-sectional direction is 0.001 mm 2 -0.3mm 2 .

4. The magnetic film according to any one of claims 1 to 3, characterized in that The multiple cracks include at least one of the following: cracks extending along the stacking direction of the composite layers to a depth equal to the stacking height of the composite layers; and cracks extending along the stacking direction of the composite layers to a depth less than the stacking height of the composite layers.

5. The magnetic film according to claim 1, wherein The opening width of each crack is less than 2 μm.

6. The magnetic film according to claim 1, wherein The thickness of each magnetic layer is 5nm-40nm.

7. The magnetic film according to claim 1, wherein The material of each magnetic layer is ferromagnetic metal or ferromagnetic alloy.

8. The magnetic film according to claim 1, wherein The dielectric layer is made of at least one of insulating oxides, nitrides or fluorides.

9. The magnetic film according to claim 1, wherein The composite layer further includes a plurality of transition layers, wherein a transition layer is formed between each adjacent magnetic layer and dielectric layer, and the thickness of the transition layer is less than or equal to 10 nm; the transition layer contains the magnetic material in the magnetic layer and the insulating material in the dielectric layer.

10. The magnetic film according to claim 9, wherein The volume proportion of the magnetic material in the transition layer is between 20% and 80%.

11. The magnetic film according to claim 1, wherein The total number of the multiple magnetic layers and the multiple dielectric layers is greater than 50, and the total thickness is greater than 300 nm.

12. The magnetic film according to claim 11, wherein The thickness of the composite layer is 1µm-10µm.

13. The magnetic film according to claim 1, wherein The thickness of the substrate is 5µm-50µm, the glass transition temperature is 25°C-100°C, and the melting point is greater than 100°C.

14. The magnetic film according to claim 13, wherein The material of the substrate is one of polyethylene terephthalate, polymethyl methacrylate, polybutadiene-styrene, polyphenylene sulfide, acrylonitrile-butadiene-styrene plastic, polyethylene terephthalate-1,4-cyclohexanedimethanol, and polystyrene.

15. The magnetic film according to claim 1, wherein The substrate is a plastic packaging material layer with a thickness of 5µm-500µm.

16. A semiconductor packaging module, characterized in that: The invention comprises an electronic component, a magnetic film as claimed in claim 15 attached to the electronic component, and a metal shielding layer attached to the magnetic film.

17. An electronic device, characterized in that: The invention comprises a circuit board and the semiconductor package module according to claim 16 located on the circuit board.

18. An electronic device, characterized in that: The semiconductor package module comprises a housing and the semiconductor package module according to claim 16 located in the housing.

19. An electronic device, characterized in that: The invention comprises a noise source radiating electromagnetic waves and the magnetic film according to any one of claims 1 to 14, wherein the magnetic film is attached to the noise source or arranged on a path where the noise source propagates noise.

20. The electronic device according to claim 19, wherein The electronic device includes a middle frame and a metal part made of metal material. The middle frame and the metal part cooperate to form a cavity. The noise source is arranged in the cavity. A signal transmitter is arranged outside the cavity. The magnetic film is located in the cavity.

21. A method for preparing a magnetic film, characterized in that: include: providing a substrate; forming a composite layer on one side of the substrate by sputtering, wherein the composite layer includes a plurality of magnetic layers and a plurality of dielectric layers, wherein the plurality of magnetic layers and the plurality of dielectric layers are alternately arranged on one side of the substrate; The thickness of each magnetic layer is 2nm-100nm; the thickness of each dielectric layer is 2nm-10nm; the thickness of the composite layer is 50nm-10µm; During the process of sputtering to form the composite layer, the internal stress in the composite layer is released, resulting in the formation of multiple cracks in the composite layer that are non-periodically distributed, at least some of the multiple cracks have different extension directions along the cross-section perpendicular to the stacking direction of the composite layer, and at least some of the multiple cracks extend non-linearly along the cross-section perpendicular to the stacking direction of the composite layer.

22. The method for preparing a magnetic thin film according to claim 21, wherein: Each magnetic layer is sputtered using a DC sputtering method, with the sputtering pressure set to 0.1Pa-10.0Pa, the sputtering rate set to 0.1nm / s-2nm / s, and the sputtering time for each layer set to 5s-100s.

23. The method for preparing a magnetic thin film according to claim 21, wherein: Each dielectric layer is deposited by radio frequency sputtering, with the sputtering pressure set to 0.1 Pa-10.0 Pa, the sputtering rate set to 0.05 nm / s-0.1 nm / s, and the sputtering time for each layer set to 5 s-500 s.

24. The method for preparing a magnetic thin film according to claim 21, wherein: The preparation method further includes forming a transition layer between each adjacent magnetic layer and dielectric layer, wherein the transition layer contains the magnetic material in the magnetic layer and the insulating material in the dielectric layer, and the thickness of the transition layer is less than or equal to 10 nm.

25. The method for preparing a magnetic thin film according to claim 24, wherein: The transition layer is co-sputtered by DC and RF, the sputtering pressure is set to 0.1Pa-10.0Pa, the sputtering rate ratio between DC and RF sputtering is adjusted to be between 0.2-5, and the sputtering time of each layer is less than or equal to 50s.

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