Magnetic shield material

Abstract

To provide a magnetic shielding material which is flexible, can be easily punched into a required shape, and has both high magnetic shielding property and bending workability in a wide frequency range from a low frequency to a high frequency.SOLUTION: In order to solve this problem, the magnetic shield material of the present invention is a magnetic shield material that surrounds a magnetic field generation source to suppress magnetic field leakage, wherein the shield material is a magnetically annealed metal-based soft magnetic material, and SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic shielding material that shields against magnetic fields, and more particularly to a magnetic shielding material that has both high magnetic shielding properties over a wide range of frequencies from low to high and bendability. [Background technology]

[0002] The development of wireless power supply systems that use magnetic resonance-based non-contact power transmission is being actively pursued, and room temperature plasma is being used for wafer surface treatment in semiconductor manufacturing.

[0003] However, these devices and processing equipment are subject to external and self-generated magnetic fields, which can cause electromagnetic noise. Magnetic shielding materials are used to mitigate the effects of these magnetic fields. Magnetic shielding materials reduce the effects of magnetic fields that cause electromagnetic noise by attracting and diverting magnetic flux that would otherwise reach signal and power lines.

[0004] During wireless power transfer, multiple receiving coils are placed near the top surface of the power transfer coil to receive power from the power transfer coil. At this time, a magnetic shield is installed between the receiving coil and the equipment to be powered by the vehicle to prevent magnetic flux from the power transfer coil from interfering with the operation of electronic circuits installed inside the vehicle. The frequency used for wireless power transfer is around 100 kHz.

[0005] In addition, the wafer surface treatment chamber of semiconductor manufacturing equipment consists of an RF source coil for generating atmospheric pressure plasma and a backshell, and the backshell is equipped with a magnetic shield made of ferromagnetic material to protect against electromagnetic compatibility and radio frequency (RF) interference. The plasma discharge frequencies used in atmospheric pressure plasma are in the kHz to MHz range for radio frequency discharge, MHz for RF plasma discharge, and MHz to GHz for microwave discharge, with higher frequencies providing better treatment performance.

[0006] For example, a magnetic shielding material has been disclosed that is 2 to 5 mm thick and contains Fe—Si—Al soft magnetic particles that have been surface-treated with a thermoplastic resin and an inorganic compound (see, for example, Patent Document 1).

[0007] Additionally, it has been disclosed that a magnetic shielding material made of a ferromagnetic material such as nickel zinc ferrite, magnesium zinc ferrite, or nickel magnesium ferrite is arranged in the back shell as a magnetic shielding material for plasma irradiation (see, for example, Patent Document 2).

[0008] Furthermore, a coating film containing a binder and a magnetic filler has been disclosed with the objective of providing a coating film that can be formed by a simple coating process and has excellent magnetic shielding properties (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2023-91105 A [Patent Document 2] Special Publication No. 2021-530852 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-21490 Summary of the Invention [Problem to be solved by the invention]

[0010] Magnetic shielding technologies are disclosed in Patent Documents 1, 2, and 3. The magnetic shielding material of the invention in Patent Document 1 discloses a magnetic shield body used in a wireless power transfer system that uses an Fe-Si-Al alloy and is capable of adequately shielding magnetic fields caused by complex shapes and high power. However, there is also the problem that the Fe-Si-Al alloy cannot provide sufficient magnetic shielding properties at high frequencies such as the discharge frequency of atmospheric pressure plasma.

[0011] The invention of Patent Document 2 can be used as a magnetic shield at the discharge frequency of atmospheric pressure plasma, and the magnetic shield can be made of ferromagnetic materials such as nickel-zinc (NiZn) ferrite, magnesium-zinc (MgZn) ferrite, ferrite made from nickel-magnesium (NiMg) alloy, and manganese-zinc (MnZn) ferrite. However, wireless power supply is not particularly taken into consideration, and there is an issue that the shielding properties at low frequencies are reduced.

[0012] Another possible method is to form a coating film with magnetic shielding properties on the surface, as described in Patent Document 3. However, such a coating film made of magnetic shielding paint has a problem in that it is thin and difficult to adequately shield the magnetic field generated by high power. The present invention has been made to solve the above-mentioned problems and relates to a magnetic shielding material that has both high magnetic shielding properties over a wide range of frequencies from low to high and bendability. [Means for solving the problem]

[0013] When it comes to magnetic shielding materials, simply laminating a low-frequency magnetic shielding sheet and a high-frequency magnetic shielding sheet results in a large thickness. While increasing the thickness can be considered to improve high-voltage magnetic shielding, increasing the thickness results in a loss of flexibility as a sheet or foil, reducing bendability and flexibility. To prevent this, a magnetic shielding material that not only has magnetic shielding properties but also bendability is required.

[0014] In order to solve the above problems, the magnetic shielding material of the present invention is a magnetic shielding material that surrounds a magnetic field generation source to suppress magnetic field leakage, and is characterized in that the shielding material is a magnetically annealed metallic soft magnetic material.

[0015] In the above configuration, the metallic soft magnetic material preferably has a saturation magnetic flux density of 0.5 T or more. The metallic soft magnetic material is preferably permalloy or permendur. Furthermore, the magnetic shielding characteristic is preferably 10 dB or more over the entire frequency range of 10 kHz to 30 GHz. Furthermore, the average particle size after magnetic annealing may be 0.3 mm or more, and the particle size regulation rate may be 70% or less. By using such a thermal shielding material, a high thermal shielding effect can be obtained over a wide range of frequencies from low to high frequencies. [Effects of the Invention]

[0016] The magnetic shielding material of the present invention is a magnetically annealed metallic soft magnetic material, and therefore has high magnetic shielding properties, excellent bending workability, and the required tensile strength, making it highly effective when used in fields where magnetic shielding properties and flexibility are required. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing a process flow of a method for manufacturing a metal-based soft magnetic material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below. (Metallic soft magnetic material)

[0019] To solve the above problems, soft magnetic metals can be used. Specifically, iron, electromagnetic soft iron, silicon steel, permalloy, sendust, permendur, ferrite, amorphous magnetic alloy, nanocrystalline magnetic alloy, ferrite material, electromagnetic stainless steel, etc. can be used. It is also possible to use a laminated material in which two or more materials are laminated. Among these magnetic metals, permalloy and permendur are preferable due to their high magnetic permeability and high saturation magnetic flux density. Permalloy is generally an alloy primarily composed of iron and nickel, and some also contain copper, molybdenum, etc. Permendur generally refers to an alloy in which iron and cobalt are mixed in a 1:1 ratio, but some also contain vanadium, etc.

[0020] The metallic soft magnetic material is in the form of a foil (sheet), and the thickness of the metallic soft magnetic material is usually 0.001 to 2 mm, preferably 0.005 to 0.8 mm, particularly preferably 0.01 to 0.2 mm, and further preferably 0.025 to 0.1 mm. If the thickness is too large, flexibility is lost, resulting in reduced bendability and softness, while if the thickness is too small, magnetic shielding properties are reduced.

[0021] In this way, the metallic soft magnetic material can be designed to have a thin overall thickness, and can be attached without any problems to the complex shapes of the inner and outer surfaces of the housings of electric and electronic devices, curved portions, wiring boards (FPC, rigid-flexible boards, rigid boards, etc.), cables (single wire, stranded wire, shielded wire, flat cable, FFC, etc.), etc. Therefore, it is possible to achieve a significant weight reduction in electric and electronic devices that have been provided with electromagnetic countermeasures. (Magnetic annealing)

[0022] A simple process flow for manufacturing metallic soft magnetic materials is shown in Figure 1. First, an alloy for soft magnetic components having a predetermined composition is melted and cast (Process 1: Melting and Casting). The cast metallic soft magnetic material is then hot-worked (Process 2: Hot Working). Subsequently, annealing is performed to remove processing strain, yielding an alloy material for the metallic soft magnetic material (Process 3: Annealing). The annealed alloy material is then cold-rolled to obtain a metallic soft magnetic material preform with processing strain (Process 4: Cold Working). The obtained soft magnetic component preform is heated and subjected to a magnetic adjustment process (Process 5: Magnetic Annealing). In order to achieve both magnetic shielding properties and bending workability, the magnetic shield material of the present invention requires magnetic annealing after the metallic soft magnetic material is worked into the product shape.

[0023] The magnetic annealing conditions are as follows: in the case of permendur, treatment is preferably performed at 700°C to 1000°C for 30 minutes to 10 hours, and more preferably at 800°C to 900°C for 1 hour to 5 hours. In the case of permalloy, treatment is preferably performed at 700°C to 1500°C for 30 minutes to 10 hours, and more preferably at 900°C to 1200°C for 1 hour to 6 hours. Good magnetic properties cannot be obtained below the lower limit temperature, and above the upper limit temperature, the material becomes non-magnetic and the magnetic properties deteriorate. Furthermore, the magnetic properties cannot be obtained if the heating time is below the lower limit time, and the magnetic properties do not change even if the heating time is above the upper limit time, so the above conditions are preferred. (crystal grain size, grain size ratio)

[0024] The crystal grain size after magnetic annealing is a factor that significantly affects the magnetic properties. Since the magnetic shielding material of the present invention has high magnetic shielding properties over a wide range of frequencies from low to high, the crystal grain size is 0.3 mm or more, preferably 0.35 mm or more, and more preferably 0.4 mm or more, and the crystal grain size is preferably 1 mm or less. On the other hand, the grain size regulation is 70% or less, preferably 60% or less, and more preferably 50% or less, with no particular lower limit. As the crystal grain size increases, the AC magnetic properties deteriorate, and as the crystal grain size decreases, the DC magnetic properties deteriorate. By reducing the grain size regulation and providing a distribution in the crystal grain size, a high level of magnetic shielding properties can be obtained over a wide range of frequencies.

[0025] The magnetic shielding material of the present invention may also be formed into a magnetic shielding adhesive sheet having an adhesive layer laminated on one or both sides thereof. By providing an adhesive layer on the magnetic shielding material, the magnetic shielding material can be attached and fixed to the desired location at any time using this adhesive layer. For ease of handling, it is desirable to cover the surface of the adhesive layer with a release liner. Even when the magnetic shielding material is not attached using an adhesive layer, a film may be attached using the adhesive layer laminated on one or both sides. Furthermore, a support film may be attached using one adhesive layer, and a release liner may be attached using the other adhesive layer. When using the magnetic shielding material of the present invention, the magnetic shielding material may be used as a single layer or multiple layers may be laminated. When multiple magnetic shielding materials are laminated, the thicknesses and compositions of the multiple magnetic shielding materials may be the same or different. (Example)

[0026] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples. The measurement methods for each property value in the following examples and comparative examples are as follows. (1) Thickness: Measured in accordance with JIS Z-0237 under a load of 60 kPa. (2) Flexibility: In accordance with JIS-P8115, the manufactured magnetic shielding material was bent 100 times. After bending, the surface condition was observed for wrinkles and cracks, and the shape was evaluated according to the following criteria. ○: No wrinkles or cracks on the surface. △: There are slight wrinkles on the surface, but no cracks. ×: Wrinkles are clearly visible on the surface and cracks have occurred. (3) Grain size and grain size ratio: In accordance with JIS G-0551, a cross section perpendicular to the rolling direction was measured using an optical microscope at 12 mm 2The diameter of the grain boundaries was measured and the average value was calculated. The proportion of grain boundaries with diameters of 0.15 mm or more was taken as the uniform grain size. (4) Magnetic properties: The maximum magnetic permeability, coercivity, and saturation magnetic flux density were measured according to JIS C-2531. The magnetic shielding material of the present invention is characterized by having a large magnetic permeability and a large saturation magnetic flux density. The saturation magnetic flux density (T) is preferably 0.5 T or more, and more preferably 0.65 T or more. The upper limit of the saturation magnetic flux density may be the maximum value possessed by the metallic soft magnetic material of the present invention. (5) Electromagnetic shielding: The electromagnetic shielding characteristics were measured below 1 GHz using the KEC method (magnetic field) and above 1 GHz using the GHz-KEC method. The target value for magnetic shielding characteristics was 10 dB or more across the entire frequency range from 10 kHz to 30 GHz. Note that, since high magnetic shielding characteristics are desirable, no upper limit was specified. The magnetic shielding material described below was prepared. (Comparative Example 1, Example 1)

[0027] An alloy consisting of 49 wt% Fe-49 wt% Co-2 wt% V was melted in a vacuum, followed by hot forging and hot rolling to obtain a hot-rolled plate material. The hot-rolled material was allowed to cool in the air without water cooling. The cooled hot-rolled material was then cold-rolled to obtain a magnetic shielding material made of permendur with a thickness of 0.05 mm (Comparative Example 1). The obtained magnetic shielding material was heated at 850°C for 3 hours for magnetic annealing. After annealing, it was cooled to room temperature at a rate of 100°C / hour to obtain a magnetic shielding material (Example 1). (Comparative Example 2, Example 2)

[0028] An alloy consisting of 16 wt% Fe-80 wt% Ni-4 wt% Mo was melted in a vacuum, followed by hot forging and hot rolling to obtain a hot-rolled plate material. The hot-rolled material was allowed to cool in the air without water cooling. The cooled hot-rolled material was then cold-rolled to obtain a magnetic shielding material made of Permalloy C with a thickness of 0.05 mm (Comparative Example 2). The obtained magnetic shielding material was heated at 1100°C for 3 hours for magnetic annealing. After annealing, it was cooled to room temperature at a rate of 100°C / hour to obtain a magnetic shielding material (Example 2). (Comparative Example 3, Example 3)

[0029] An alloy consisting of 55 wt% Fe-45 wt% Ni was melted in a vacuum, followed by hot forging and hot rolling to obtain a hot-rolled plate material. The hot-rolled material was allowed to cool in the air without water cooling. The cooled hot-rolled material was then cold-rolled to obtain a magnetic shielding material made of Permalloy B with a thickness of 0.03 mm (Comparative Example 3). The obtained magnetic shielding material was heated at 1100°C for 3 hours for magnetic annealing. After annealing, the material was cooled to room temperature at a rate of 100°C / hour to obtain a magnetic shielding material (Example 3). Table 1 shows the compositions, magnetic annealing conditions, shapes, magnetic properties, and electromagnetic shielding properties of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3.

[0030] [Table 1]

[0031] Example 1 and Comparative Example 1 were made of permendur, a soft magnetic material. Example 1 was characterized by the fact that the material of Comparative Example 1 was further subjected to magnetic annealing. The average particle size and sizing rate for Example 1 were 0.4 mm and 40%, respectively, while those for Comparative Example 1 were 0.3 mm and 87%. Reflecting the annealing effect, the magnetic properties were as follows: maximum permeability was 2000 for Comparative Example 1 compared to 2000 for Example 1, coercivity was 250 A / m for Comparative Example 1 compared to 50 A / m for Example 1, and saturation magnetic flux density was 2.1 T for Comparative Example 1 compared to 2.5 T for Example 1. Furthermore, Example 1 achieved electromagnetic shielding properties of 10 dB or more in all frequency ranges from 40 kHz to 18 GHz. On the other hand, Comparative Example 1 achieved electromagnetic shielding properties of 10 dB or more above 200 kHz, but less than 10 dB below 100 kHz. These results demonstrate that magnetic annealing of permendur can provide excellent electromagnetic shielding properties.

[0032] Example 2 and Comparative Example 2 consisted of Permalloy C composed of 16 wt% Fe, 80 wt% Ni, and 4 wt% Mo. Example 2 was characterized by the fact that the material of Comparative Example 2 was further subjected to magnetic annealing. The average particle size and granularity of Example 2 were 0.42 mm and 45%, respectively, while those of Comparative Example 2 were 0.3 mm and 92%. Reflecting the annealing effect, the magnetic properties were as follows: maximum permeability was 70,000 for Comparative Example 2 versus 200,000 for Example 2, coercivity was 3 A / m for Comparative Example 2 versus 0.5 A / m for Example 2, and saturation magnetic flux density was 0.7 T for Comparative Example 2 versus 0.8 T for Example 2. Furthermore, Example 2 achieved electromagnetic shielding characteristics of 10 dB or greater across all frequency ranges from 40 kHz to 18 GHz. On the other hand, Comparative Example 2 achieved values ​​less than 10 dB across all frequency ranges from 40 kHz to 18 GHz. As a result, it was found that magnetic annealing of Permalloy C can provide good electromagnetic shielding properties.

[0033] Example 3 and Comparative Example 3 were made of Permalloy B composed of 55 wt% Fe and 45 wt% Ni, and Example 3 was characterized by the fact that the material of Comparative Example 3 was further subjected to magnetic annealing. The average particle size and sizing rate of Example 3 were 0.45 mm and 40%, respectively, while those of Comparative Example 3 were 0.40 mm and 90%. Reflecting the annealing effect, the magnetic properties were as follows: maximum permeability was 10,000 for Comparative Example 3 and 50,000 for Example 3; coercivity was 50 A / m for Comparative Example 3 and 12 A / m for Example 3; and saturation magnetic flux density was 1.5 T for Comparative Example 3 and 1.6 T for Example 3. Furthermore, Example 3 achieved electromagnetic shielding properties of 10 dB or more in all frequency ranges from 40 kHz to 18 GHz. Comparative Example 3 achieved electromagnetic shielding properties of 10 dB or more at frequencies above 200 kHz, but less than 10 dB below 100 kHz. As a result, it was found that magnetic annealing of Permalloy B can provide good electromagnetic shielding properties.

[0034] Since the magnetic shielding material of the present invention is in a foil form, it can be easily processed into an appropriate size, shape, etc., by applying known methods according to its purpose and application. It can also be deformed into any shape so as to cover a magnetic source. The shape is not limited to a linear shape, but can also be a curved shape. Therefore, it can be used for a variety of applications.

[0035] For example, the housing of a plasma processing apparatus can be made of the magnetic shielding material of the present invention or the magnetic shielding material of the present invention can be attached thereto. Furthermore, the housing of a mobile terminal such as a mobile phone, a smartphone, a tablet terminal, or a notebook personal computer can be made of the magnetic shielding material of the present invention or the magnetic shielding material of the present invention can be attached thereto. This makes it possible to shield the plasma processing apparatus, modular equipment, elements, batteries, wire harnesses, wireless charging systems, and the like mounted on the mobile terminal from leaking magnetism to the outside. [Industrial Applicability]

[0036] The magnetic shielding material of the present invention is in foil form, and therefore is flexible and can be easily punched into the required shape. It is also thin and lightweight, and has both high magnetic shielding properties over a wide range of frequencies from low to high frequencies and bendability, making it useful in a wide range of fields.

Claims

1. A magnetic shielding material that surrounds a magnetic field source to suppress magnetic field leakage, characterized in that the shielding material is a magnetically annealed metallic soft magnetic material.

2. 2. The magnetic shield material according to claim 1, wherein the metallic soft magnetic material has a saturation magnetic flux density of 0.5 T or more.

3. 2. The magnetic shield material according to claim 1, wherein the metallic soft magnetic material is permalloy or permendur.

4. 2. The magnetic shielding material according to claim 1, wherein the magnetic shielding effect is 10 dB or more over the entire frequency range from 10 kHz to 30 GHz.

5. 2. The magnetic shield material according to claim 1, wherein the average grain size after magnetic annealing is 0.3 mm or more and the grain size regulation rate is 70% or less.

Images