Metal ferrite composite magnetic shielding material

Abstract

The present application relates to a kind of metal ferrite composite magnetic shielding materials, comprising: substrate, the substrate is non-magnetic material;At least one shielding unit fixed on the surface of the substrate, the shielding unit includes ferrite layer composed of several similar shapes, different sizes and concentrically arranged ferrite rings, and metal layer composed of several similar shapes, different sizes and concentrically arranged metal rings, several the metal ring and several the ferrite ring are one-to-one corresponding and fixed, the ferrite layer is fixed on the substrate.The composite magnetic shielding material of the present application can have smaller eddy current heat effect and smaller mass and volume of shielding body under the premise of ensuring higher shielding efficiency.

Description

Technical Field

[0001] This invention relates to the field of magnetic shielding technology, and in particular to a metal ferrite composite magnetic shielding material. Background Technology

[0002] Composite magnetic shielding structures are effective shielding mechanisms against magnetic field interference. Composed of both magnetic and non-magnetic materials, they are manufactured using advanced processes to achieve excellent magnetic shielding performance. They are widely used in applications susceptible to electromagnetic interference, such as ultrasonic gas meters, ultrasonic probes, and wireless power transmission. Precision instruments and equipment like ultrasonic gas meters typically require high levels of protection to prevent interference and damage from external magnetic fields. In wireless power transmission, external magnetic field interference can affect transmission efficiency, and strong magnetic field radiation from both sides of the coil can cause serious harm to the surrounding environment and human health. The application of composite magnetic shielding structures effectively solves these problems, improves the performance and reliability of instruments and equipment, and enhances the stability of wireless power transmission.

[0003] In practical applications, both metallic and ferrite materials can provide magnetic shielding, but their application in the high-frequency range is limited. Metallic shields can block high-frequency alternating magnetic fields, which induce large eddy currents. Due to the demagnetizing effect of these eddy currents, the magnetic field at the shield is significantly weakened. The high-frequency alternating magnetic field inside the shield cannot escape, and the magnetic field outside the shield cannot penetrate, thus achieving magnetic shielding. However, in high-power equipment, this can lead to eddy current heating, causing overheating and affecting normal operation, posing a significant safety hazard. Ferrite magnetic materials are characterized by a much higher resistivity than metallic magnetic materials, resulting in smaller eddy currents, making them suitable for high-power applications. However, ferrite magnetic materials suffer from high high-frequency power loss and poor shielding effectiveness. Furthermore, the shielding effectiveness of ferrite magnetic materials is related to their thickness; therefore, achieving high shielding effectiveness typically requires ferrite magnetic materials with greater mass and volume, making them unsuitable for miniaturization and lightweight requirements. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a metal ferrite composite magnetic shielding material that, while ensuring high shielding effectiveness, exhibits a small eddy current heating effect and a small shielding mass and volume.

[0005] This invention is achieved through the following scheme: a metal ferrite composite magnetic shielding material, comprising:

[0006] A substrate, wherein the substrate is a non-magnetic material;

[0007] At least one shielding unit is fixed to the surface of the substrate. The shielding unit includes a ferrite layer composed of several ferrite rings of similar shape, different size and concentrically arranged, and a metal layer composed of several metal rings of similar shape, different size and concentrically arranged. Several metal rings are attached and fixed one-to-one with several ferrite rings. The ferrite layer is fixed to the substrate.

[0008] A further improvement of the metal ferrite composite magnetic shielding material of the present invention is that the material of the metal ring is selected from copper, iron, aluminum, silver, gold and their alloys.

[0009] A further improvement of the metal ferrite composite magnetic shielding material of the present invention is that the innermost ferrite ring extends inward to form a solid ferrite plate, and the innermost metal ring extends inward to form a solid metal plate.

[0010] A further improvement of the metal ferrite composite magnetic shielding material of the present invention is that the outer diameter of the innermost ferrite ring does not exceed 1 / 3 of the outer diameter of the outermost ferrite ring.

[0011] A further improvement of the metal-ferrite composite magnetic shielding material of the present invention is that the thickness of the metal layer is the same as the thickness of the ferrite layer.

[0012] A further improvement of the metal-ferrite composite magnetic shielding material of the present invention is that the thickness of the substrate is equal to the sum of the thickness of the metal layer and the thickness of the ferrite layer.

[0013] A further improvement of the metal ferrite composite magnetic shielding material of the present invention is that the number of shielding units is multiple, and the multiple shielding units are fixed on the surface of the substrate in a matrix distribution.

[0014] A further improvement of the metal ferrite composite magnetic shielding material of the present invention is that the substrate is a flexible substrate.

[0015] This invention employs a concentric double-layer structure of metal rings and ferrite rings to shield magnetic fields. On one hand, the high permeability of the ferrite layer compresses the magnetic field to be shielded, thereby weakening the magnetic field penetrating the metal layer and reducing the eddy current heating effect of the metal layer. On the other hand, the high shielding performance of the metal layer avoids the need to increase the mass and volume of the ferrite layer to improve shielding effectiveness. This invention uses a flexible substrate to fix the metal and ferrite rings, allowing the composite magnetic shielding material to be freely bent and folded, and resulting in a thinner, flatter structure that improves overall structural flexibility. Furthermore, arranging multiple sets of metal and ferrite rings in an array increases the magnetic shielding area, making it suitable for a wider range of magnetic shielding applications. Attached Figure Description

[0016] Figure 1A front view of the layered state of the composite magnetic shielding material of the present invention is shown.

[0017] Figure 2 A side view of the composite magnetic shielding material of the present invention in a layered state is shown.

[0018] Figure 3 A schematic diagram of the ferrite layer and equivalent current flow direction of the present invention is shown.

[0019] Figure 4 A schematic diagram of the metal layer and equivalent current flow direction of the present invention is shown.

[0020] Figure 5 A schematic diagram of the metal magnetic shielding structure of the present invention is shown.

[0021] Figure 6 A schematic diagram of the composite magnetic shielding structure of the present invention is shown.

[0022] Figure 7 A schematic diagram illustrating the shielding effectiveness of the composite magnetic shielding structure and the metal magnetic shielding structure of the present invention is shown. Detailed Implementation

[0023] To address the limitations of traditional shielding materials in simultaneously achieving high shielding effectiveness, low eddy current heating, and small shield size, this invention provides a metal-ferrite composite magnetic shielding material that, while maintaining high shielding effectiveness, exhibits low eddy current heating and a small shield mass and volume. The following detailed description, in conjunction with accompanying drawings, illustrates this metal-ferrite composite magnetic shielding material with specific embodiments.

[0024] See Figure 1 and Figure 2 As shown, a metal ferrite composite magnetic shielding material includes: a substrate 1, which is a non-magnetic material; at least one shielding unit fixed to the surface of the substrate 1, the shielding unit including a ferrite layer 2 composed of a plurality of ferrite rings 21 of similar shape but different size and concentrically arranged, and a metal layer 3 composed of a plurality of metal rings 31 of similar shape but different size and concentrically arranged, wherein the plurality of metal rings 31 are attached and fixed one-to-one with the plurality of ferrite rings 21, and the ferrite layer 2 is fixed to the substrate 1.

[0025] Specifically, in coordination Figure 3 and Figure 4As shown, the composite magnetic shielding material includes a shielding unit consisting of a metal ring 31, a ferrite ring 21, and a substrate 1 from top to bottom. The unit measures 30mm x 30mm. Both the ferrite layer 2 and the metal layer 3 are concentric square rings. The outermost ferrite ring 21 and the outermost metal ring 31 have a side length L1 of 30mm. The innermost ferrite ring 21 extends inward and closes, forming a solid square ferrite plate in the center. The innermost metal ring 31 extends inward and closes, forming a solid square metal plate in the center. The side length L2 of the solid ferrite plate and the solid metal plate is generally no greater than 1 / 3 of the shielding unit size; in this embodiment, L2 is 10mm. The metal ring 31 can be made of copper, iron, aluminum, silver, gold, or their alloys. In this embodiment, copper, which has high conductivity and relatively low cost, is chosen to make the metal ring 31. Preferably, the thickness of the metal layer 3 is the same as the thickness of the ferrite layer 2, both being d = 0.1 mm, and the thickness of the substrate 1 is equal to the sum of the thicknesses of the metal layer 3 and the ferrite layer 2, which is 2d = 0.2 mm, specifically as follows: Figure 2 As shown.

[0026] Let the effective induced currents of ferrite ring 21 and metal ring 31 be represented by I1 and I2, respectively. Assuming the magnetic field to be shielded has a current I flowing from the inside out, then the current I1 in the ferrite region is in the same direction as I. Since the metal is diamagnetic, the current I2 is in the opposite direction to I1 and I. By generating a clockwise and counterclockwise alternating magnetic moment distribution between the air and the metal, the entire structure ultimately forms a Halbach-like magnetic circuit in the magnetic field. The Halbach-like magnetic moment structure constructed under the excitation magnetic field of the magnetic dipole source is similar to the magnetic circuit of the Halbach permanent magnet array. It should be noted that the distance between the ferrite layer 2 and the metal layer 3 in each shielding unit, as well as the number of ferrite rings 21 and metal rings 31, can be designed. Theoretically, the more rings, the higher the equivalent permeability of the system, and the closer the system is to a Halbach-like magnetic circuit. This type of Halbach magnetic circuit structure, on the one hand, utilizes the high permeability of the ferrite layer to compress the magnetic field to be shielded, thereby weakening the magnetic field penetrating the metal layer and reducing the eddy current heating effect of the metal layer. On the other hand, it leverages the high shielding performance of the metal layer, avoiding the need to increase the mass and volume of the ferrite layer to improve shielding effectiveness. Furthermore, this type of Halbach structure can also control the asymmetric magnetic field distribution by adjusting the corresponding angles of the two shielding units to change the magnetic moment. This has significant advantages in achieving efficient near-field magnetic shielding and suppressing boundary leakage magnetic field.

[0027] As a preferred embodiment, for applications with a large shielding space, a larger substrate 1 can be used, and multiple shielding units can be fixed in a matrix on the surface of the substrate 1 to increase the shielding area. Furthermore, for ease of storage, the substrate 1 can be made of a flexible substrate, such as PCB material, allowing the composite magnetic shielding material to be freely bent and folded, and resulting in a lighter, thinner, and flatter overall structure, thus improving the overall flexibility of the structure.

[0028] The shielding effectiveness of traditional metallic magnetic shielding materials and the composite magnetic shielding material of this invention will be compared through experiments below.

[0029] See Figures 5-7 As shown, Figure 5 The diagram shows a metal magnetic shielding structure using traditional metal magnetic shielding material as the shield. The transmitting coil 3 and receiving coil 2 used in the experiment have the same structure and dimensions, and are both non-resonant coils, measuring 30mm x 30mm. The receiving coil 2 is connected to port 1 of the network analyzer, and the transmitting coil 3 is connected to port 2 of the network analyzer. The shield 1 between the two coils is a copper plate. The distance between the transmitting coil 3 and the shield 1 is 5mm, and the distance between the shield 1 and the receiving coil 2 is S, which is set to 280mm here.

[0030] Figure 6 The diagram shows a composite magnetic shielding structure using the composite magnetic shielding material of the present invention as the shielding body. The transmitting coil 3, receiving coil 2, and the distance between them and the shielding body 1 used in the experiment are the same as those in the metal magnetic shielding structure. The difference is that the shielding body 1 is replaced by a metal ferrite composite magnetic shielding material instead of a copper plate.

[0031] Figure 7 The figures show the shielding effectiveness curves of the metallic magnetic shielding structure and the composite magnetic shielding structure in the range of 400kHz to 600kHz. Specifically, the straight line represents the shielding effectiveness curve of the composite magnetic shielding structure, and the dashed line represents the shielding effectiveness curve of the metallic magnetic shielding structure. It is clearly evident that, within the range of 400kHz to 600kHz, the shielding effectiveness of the composite magnetic shielding structure is consistently higher than that of the metallic magnetic shielding structure. Therefore, the metallic ferrite composite magnetic shielding material of this invention can achieve high shielding effectiveness while exhibiting a smaller eddy current heating effect and a smaller mass and volume of the shielding body.

[0032] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A metal ferrite composite magnetic shielding material, characterized in that, include: A substrate, wherein the substrate is a non-magnetic material; Multiple shielding units are fixed on the surface of the substrate. The multiple shielding units are fixed on the surface of the substrate in a matrix arrangement. Each shielding unit includes a ferrite layer composed of several ferrite rings of similar shape but different size and concentrically arranged, and a metal layer composed of several metal rings of similar shape but different size and concentrically arranged. Several metal rings and several ferrite rings are attached and fixed one-to-one. The ferrite layer is fixed on the substrate. The ferrite layer and the metal layer form a Halbach-like magnetic circuit under the excitation magnetic field of the magnetic dipole source. The corresponding angles of the two shielding units are adjustable to control the asymmetrical magnetic field distribution.

2. The metal ferrite composite magnetic shielding material as described in claim 1, characterized in that, The metal ring is made of copper, iron, aluminum, silver, gold, or their alloys.

3. The metal ferrite composite magnetic shielding material as described in claim 1, characterized in that, The innermost ferrite ring extends inward to form a solid ferrite plate, and the innermost metal ring extends inward to form a solid metal plate.

4. The metal ferrite composite magnetic shielding material as described in claim 3, characterized in that, The outer diameter of the innermost ferrite ring does not exceed 1 / 3 of the outer diameter of the outermost ferrite ring.

5. The metal ferrite composite magnetic shielding material as described in claim 1, characterized in that, The thickness of the metal layer is the same as the thickness of the ferrite layer.

6. The metal ferrite composite magnetic shielding material as described in claim 1, characterized in that, The thickness of the substrate is equal to the sum of the thickness of the metal layer and the thickness of the ferrite layer.

7. The metal ferrite composite magnetic shielding material as described in claim 1, characterized in that, The substrate is a flexible substrate.

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