TW201909199A - Near field noise suppression sheet including a substrate and a soft magnetic alloy powder - Google Patents

Abstract

This invention provides a near-field noise suppression sheet capable of coping with high frequency of mutual decoupling even if the thickness of the noise suppression sheet is reduced. The near-field noise suppression sheet of this invention is characterized by including a substrate made of an organic material and a soft magnetic alloy powder supported in the substrate, wherein the soft magnetic alloy powder has an average particle diameter of 12 [mu]m or less, and an average value of an aspect ratio of 1.00 or more and 1.30 or less.

Description

Near field noise suppression film

The present invention relates to a near-field noise suppression sheet used for suppressing excessive radiated electromagnetic waves (noise) of an electronic device or a communication device or magnetic coupling between a line or an electronic component.

In recent years, with the miniaturization and weight reduction of electronic equipment and communication equipment, the mounting density of electronic components mounted on electronic circuits has also increased. Therefore, due to electromagnetic wave noise radiated from an electronic component or magnetic coupling between a line or an electronic component, malfunction of an electronic device or a communication device caused by electromagnetic wave interference between electronic components or between electronic circuits becomes a problem.

In order to prevent this problem, a near-field noise suppression sheet that converts excess radiated electromagnetic waves (noise) into heat is mounted on a device or the like. Since the noise suppressing sheet has a thickness of 0.1 mm to 2 mm, it can be used by directly bonding to an electronic component or an electronic circuit as a noise generating source or adhering to an electronic component or an electronic circuit, and the processing is easy and the degree of freedom of the shape is used. Also high. Therefore, the noise suppression sheet can be adapted to miniaturization and weight reduction of an electronic device or a communication device, and widely used as a noise countermeasure component of an electronic device or a communication device.

The following three types of use methods of the noise suppression sheet are mentioned. That is, (i) the case where the noise suppression sheet is mounted in parallel with respect to the line or the electronic component, and (ii) the noise suppression sheet is mounted on the line, for the spatial coupling of the parallel parallel lines or electronic components. Or the case of the gap of the electronic component, and (iii) the case where the noise suppression sheet is mounted so as to cover the line. In the case of the above (i), the internal decoupling property of the noise suppression sheet becomes important, and in the case of the above (ii), the mutual decoupling property of the noise suppression sheet becomes important, in the above (iii) In this case, the transmission decoupling of the noise suppression sheet becomes important. That is, the internal decoupling ratio, mutual decoupling ratio, or transmission decoupling ratio of the internal decoupling property, the mutual decoupling property, or the transmission decoupling property of the noise suppression sheet becomes 0 dB according to the above (i)~( The method of use of iii) is highly sensitive to the frequency of the electromagnetic wave noise to be absorbed.

Here, a typical noise suppressing sheet is composed of a soft magnetic alloy powder processed into a flat shape and an organic binder, and the noise is converted into heat by magnetic loss caused by magnetic resonance of the soft magnetic alloy powder. Therefore, the noise suppression performance of the noise suppression sheet depends on the magnetic permeability of the soft magnetic alloy powder contained in the noise suppression sheet. Usually, the magnetic permeability is expressed by the complex magnetic permeability μ' and the imaginary magnetic permeability μ" and the complex magnetic permeability μ = μ'-j·μ", but the magnetic loss is used as in the noise suppression sheet. In the meantime, the imaginary magnetic permeability μ" is important. Moreover, the reason why the soft magnetic alloy powder processed into a flat shape is used is that the soft magnetic alloy with respect to the in-plane direction of the noise suppression sheet can be improved by performing the flat processing. Since the magnetic anisotropy of the powder is utilized, by using the magnetic anisotropy, the distribution of the imaginary magnetic permeability μ" can be controlled in accordance with the frequency of the electromagnetic wave noise to be absorbed.

Patent Document 1 describes a noise suppressing sheet characterized by having a flat magnetic powder and an organic binder. Further, Patent Document 2 describes an electromagnetic interference suppressor mainly containing flat soft magnetic particles composed of an iron-based amorphous alloy and an organic binder. [Prior Art Document] [Patent Literature]

[Patent Document 1] JP-A-2013-17465 (Patent Document 2) JP-A-2015-46538

[Problems to be Solved by the Invention] In recent years, the performance of electronic devices and communication devices has rapidly increased, and the frequency of use has been increasing. For example, in the personal computer, further speeding is required, and the driving frequency of the CPU is up to the GHz band. Moreover, the capacity of digital content processed in a communication device such as a wireless LAN is increased, and the communication frequency is also gradually dominant in the GHz band. In addition, satellite communications such as digital TV broadcasting or road traffic information systems have also rapidly expanded, and the ubiquitous network era is gradually being realized. The multi-functionality and integration of such information communication devices are progressing. On the other hand, the frequency of unnecessary electromagnetic wave noise radiated from electronic devices or communication devices is also increased, and the functional interference or malfunction caused by the electromagnetic wave noise is also higher than that of the past. Increased and worrying. Therefore, it is desirable to effectively absorb electromagnetic wave noise in the GHz band.

Further, a typical noise suppressing sheet has a structure in which flat soft magnetic alloy powders are horizontally arranged along the in-plane direction of the noise suppressing sheet, and therefore the imaginary magnetic permeability μ of the in-plane direction of the noise suppressing sheet is "" It is large, but the imaginary magnetic permeability μ" in the thickness direction of the noise suppression sheet is small. Therefore, when such a noise suppression sheet is used in the same in-plane direction as the noise source as in the above (i) or (iii), the case where the imaginary magnetic permeability μ" in the in-plane direction is large is the cause. Excellent internal decoupling and transmission fading can be obtained. However, in the case where the noise suppression sheet is used in the direction opposite to the noise source as in the above (ii), the thickness of the noise suppression sheet is imaginary. The case where the magnetic permeability μ" is small is a cause, and the mutual decoupling property of the noise suppression sheets is poor. In Patent Document 1 and Patent Document 2, flat alloy powders subjected to flat processing are used. Therefore, the techniques described in Patent Document 1 and Patent Document 2 are related to the imaginary magnetic permeability μ of the noise suppression sheet or the electromagnetic interference suppressing body in the in-plane direction, and the thickness of the noise suppression sheet or the electromagnetic interference suppressing body. Since the imaginary magnetic permeability μ" of the direction is not considered, it is possible to cope with the high frequency of the internal decoupling property and the transmission fading property, but it is not possible to cope with the high frequency of the mutual decoupling property.

In addition, even if a noise suppressing sheet made of a soft magnetic alloy powder processed into a flat shape is inserted into a conductor sheet such as a metal foil to the noise suppressing sheet, excellent mutual decoupling property can be obtained by the eddy current loss of the conductor sheet. However, with the miniaturization and weight reduction of electronic equipment and the like, when a conductor piece is inserted into an electronic circuit in which a line or an electronic component is dense, the inserted conductor piece may become a noise source instead. Therefore, a multilayer noise suppressing sheet in which a conductor layer is inserted between two layers having a flat soft magnetic alloy powder aligned in the in-plane direction of the sheet has been developed. However, in the multilayer noise suppression sheet, since the thickness of the structural upper sheet is increased, it is impossible to cope with the thinning of electronic equipment and the like in recent years. Further, the structure of the multilayer noise suppression sheet is complicated as compared with the noise suppression sheet having no conductor layer, and the manufacturing cost is also increased.

In view of the above, it is an object of the present invention to provide a near-field noise suppressing sheet capable of coping with high frequency decoupling properties even when the thickness of the noise suppressing sheet is reduced.

[Means for Solving the Problem] In order to achieve the above object, the inventors of the present invention have conducted intensive studies and obtained the following findings. In order to obtain a noise suppression sheet which can cope with mutual decoupling even if the thickness of the noise suppression sheet is reduced, it is preferable to make the long diameter direction of the flat soft magnetic alloy powder and the thickness direction of the noise suppression sheet. The flat soft magnetic alloy powder is aligned in a parallel manner. However, it is practically difficult to arrange the flat soft magnetic alloy powders in such a manner as to be aligned. Therefore, the inventors of the present invention have found that the thickness of the soft magnetic alloy powder can be changed even if the shape of the soft magnetic alloy powder is close to a spherical shape and the average particle diameter of the soft magnetic alloy powder is reduced. Thin can also cope with high-frequency noise suppression sheets that are decoupled from each other.

The present invention has been completed based on the above findings, and its main structure is as follows. (1) A near-field noise suppression sheet, wherein the near-field noise suppression sheet includes a substrate made of an organic substance and a soft magnetic alloy powder carried in the substrate, wherein The soft magnetic alloy powder has an average particle diameter of 12 μm or less, and an average value of the aspect ratio is 1.00 or more and 1.30 or less.

(2) The near-field noise suppression sheet according to the above (1), wherein the soft magnetic alloy powder has an average particle diameter of 5 μm or less.

(3) The near-field noise suppression sheet according to the above (1) or (2), wherein the soft magnetic alloy powder is composed of an alloy powder composed of only an amorphous phase and an alloy having an amorphous phase and a crystalline phase. It is composed of one or more alloy powders selected from the powder.

(4) The near-field noise suppression sheet according to the above (3), wherein the soft magnetic alloy powder includes one or more alloy powders selected from the group consisting of Fe-based alloy powders and Co-based alloy powders.

(5) The near-field noise suppression sheet according to the above (4), wherein a total concentration of Fe and Co of the one or more alloy powders selected from the Fe-based alloy powder and the Co-based alloy powder is 83 More than % by mass.

(6) The near-field noise suppression sheet according to the above (1) or (2), wherein the soft magnetic alloy powder is composed of an alloy powder composed only of a crystal phase.

(7) The near-field noise suppression sheet according to any one of the above aspects, wherein the surface resistance is 10 ⁸ Ω/□ or more.

The near-field noise suppression sheet according to any one of the above aspects, wherein the thickness is 0.5 mm or less.

[Effects of the Invention] According to the present invention, it is possible to provide a near-field noise suppression sheet capable of coping with high frequency decoupling properties even when the thickness of the noise suppression sheet is reduced.

Hereinafter, an embodiment of the near field noise suppression sheet of the present invention will be described.

A near-field noise suppression sheet (hereinafter simply referred to as a "noise suppression sheet") according to an embodiment of the present invention includes a substrate made of an organic material and a soft magnetic alloy carried on the substrate. The powder, wherein the soft magnetic alloy powder has an average particle diameter of 12 μm or less, and an average value of the aspect ratio is 1.00 or more and 1.30 or less. When the average particle diameter of the soft magnetic alloy powder is 12 μm or less and the average value of the aspect ratio is 1.00 or more and 1.30 or less, it is possible to cope with mutual decoupling even if the thickness of the noise suppression sheet is reduced. High frequency noise suppression sheet. Moreover, the noise suppression sheet of the present invention has a simpler structure than the multilayer noise suppression sheet having a conductor layer, and thus the manufacturing cost can be suppressed. In addition, since the depth of penetration of the electromagnetic wave into the magnetic material is shallower as the frequency is higher, it is preferable to further reduce the average particle diameter of the soft magnetic alloy powder from the viewpoint of further increasing the mutual decoupling property. The average particle diameter of the soft magnetic alloy powder is 5 μm or less, and the average value of the aspect ratio is 1.00 or more and 1.30 or less.

As the soft magnetic alloy powder used in the present invention, any soft magnetic alloy powder can be used. However, the depth of penetration of electromagnetic waves into the magnetic material is deeper as the resistance of the magnetic material is higher. Therefore, in consideration of the fact that the electric resistance in the amorphous phase is higher than the electric resistance in the crystal phase, a soft magnetic alloy powder containing a specific composition having an amorphous phase may be selected from the soft magnetic alloy powder. Therefore, from the viewpoint of further increasing the mutual decoupling property by increasing the electric resistance of the magnetic material, it is preferable to use an alloy composed of only an amorphous phase including a resistor having a higher electrical resistance than an alloy powder composed only of a crystal phase. A soft magnetic alloy powder of one or more alloy powders selected from the group consisting of powders and alloy powders having an amorphous phase and a crystalline phase. Further, from the viewpoint of further increasing the mutual decoupling property by obtaining a higher electric resistance, it is more preferable to use an alloy powder composed of only an amorphous phase and an alloy powder having an amorphous phase and a crystalline phase. A soft magnetic alloy powder composed of one or more kinds of alloy powders.

When a soft magnetic alloy powder containing one or more alloy powders selected from the group consisting of an alloy powder composed only of an amorphous phase and an alloy powder having an amorphous phase and a crystal phase is used, it is preferably used from the viewpoint of practicality. A soft magnetic alloy powder containing one or more alloy powders selected from Fe-based alloy powders and Co-based alloy powders. Further, it is more preferable to use a soft magnetic alloy powder composed of one or more alloy powders selected from Fe-based alloy powders and Co-based alloy powders. In addition, it is more preferable that the total concentration of Fe and Co in one or more alloy powders selected from the Fe-based alloy powder and the Co-based alloy powder is 83% by mass or more from the viewpoint of practicality. Here, examples of the alloy powder composed of only amorphous materials include Fe-based alloy powders such as FeCo-based, FeSiB-based, FePC-based, and FeCoSiB-based alloys, and Co-based alloy powders such as CoFe-based, CoSiB-based, and CoFeSiB-based alloy powders. In addition, the alloy powder which has an amorphous phase and a crystal phase is an alloy powder which precipitates the α-Fe microcrystal by performing the process mentioned later on the alloy powder which consists of only the amorphous phase mentioned above.

Further, as the soft magnetic alloy powder used in the present invention, a soft magnetic alloy powder containing an alloy powder composed only of a crystal phase may be used. In this case, it is preferable to use a soft magnetic alloy powder containing one or more alloy powders selected from Fe-based alloy powders and Co-based alloy powders from the viewpoint of practicality. Further, from the viewpoint of practicality, it is more preferable to use a soft magnetic alloy powder composed of one or more alloy powders selected from Fe-based alloy powders and Co-based alloy powders. Here, examples of the alloy powder composed only of the crystal phase include Fe-based alloy powders such as FeSi-based, FeMn-based, FeNi-based, FeSiAl-based, and FeSiCr-based alloys, and Co-based alloy powders such as CoNi and CoMn.

In addition, the soft magnetic alloy powder to be used in the present invention may be selected from two or more selected from the group consisting of an alloy powder composed only of a crystal phase, an alloy powder composed only of an amorphous phase, and an alloy powder having an amorphous phase and a crystal phase. A mixed powder of alloy powders. The ratio of the powder in this case is not particularly limited, but the total of the alloy powder composed only of the amorphous phase and the alloy powder having the amorphous phase and the crystal phase is preferably 50% by mass or more. Further, Fe powder may be added to the soft magnetic alloy powder used in the present invention to form a mixed powder. The ratio of the powder in this case is not particularly limited, but the total of the soft magnetic alloy powders in the mixed powder is preferably 50% by mass or more.

The surface resistance of the noise suppression sheet is preferably 10 ⁸ Ω/□ or more. This is because if the surface resistance of the noise suppression sheet is 10 ⁸ Ω/□ or more, even if the noise suppression sheet is directly attached to the electronic circuit and used, the impedance of the electronic circuit is not disturbed.

The thickness of the noise suppression sheet is preferably 0.5 mm or less. This is because, if the thickness of the noise suppression sheet is 0.5 mm or less, it can be applied to recent electronic devices or communication devices that are light, thin, and high-frequency. In addition, it is more preferable that the thickness of the noise suppression sheet is 0.2 mm or less.

Hereinafter, an example of a method of manufacturing the noise suppression sheet of the present embodiment will be described.

In the method for producing a noise suppression sheet of the present embodiment, first, a soft magnetic alloy powder, an organic material, and an organic solvent are mixed to prepare a slurry.

In the present invention, it is characterized in that the anisotropy of the shape of the soft magnetic alloy powder is reduced and becomes a shape close to a spherical shape. Therefore, it is important that the average value of the aspect ratio (=long diameter/thickness) of the soft magnetic alloy powder of the present invention is 1.00 or more and 1.30 or less. From such a viewpoint, the soft magnetic alloy powder of the present invention is preferably an atomized powder which is not subjected to flat processing. Here, it is assumed that the atomized powder is easily formed into a shape close to a spherical shape by an atomization method. In addition, although the atomized powder can be obtained by a gas atomization method or a water atomization method which is a general powder synthesis method, it is particularly preferable to use water from the viewpoint of obtaining a powder having a small average particle diameter as in the present invention. Atomization method. In addition, the soft magnetic alloy powder of the present invention is not limited to the structure obtained by the atomization method, and a powder obtained by pulverizing a block or a strip of a soft magnetic alloy may be used. The average particle diameter of the soft magnetic alloy powder is adjusted to 12 μm or less, and more preferably 5 μm or less by the above method.

In the present specification, the "average particle diameter" is a polished surface of a cross section in the thickness direction of the noise suppression sheet at a magnification of 5000 times by a scanning electron microscope (SEM). The powder has an average value of the long diameter of the soft magnetic alloy powder. In addition, the "average aspect ratio" is a long diameter/thickness of all the powder in the field of view with respect to the soft magnetic alloy powder when the polishing surface of the cross section of the noise suppression sheet in the thickness direction is observed by SEM at a magnification of 5000 times. The value is averaged after the value.

Further, as described above, as the soft magnetic alloy powder of the present invention, an alloy powder having an amorphous phase and a crystalline phase can be used. In the case of using an alloy powder having an amorphous phase and a crystalline phase, after an alloy powder composed only of an amorphous phase is produced, heat treatment is performed in an inert atmosphere such as nitrogen or argon to make, for example, α-Fe. Microcrystalline precipitation. The soft magnetic properties are improved by precipitating the ferromagnetic α-Fe microcrystals. That is, the magnetic flux density increases, and the coercive force and magnetostriction decrease. Thus, an alloy powder having an amorphous phase and a crystalline phase can be obtained. The heat treatment conditions can be, for example, a temperature of 300 to 600 ° C for 0.1 to 2 hours.

Examples of the organic material constituting the substrate include an epoxy resin, a phenol resin, a cellulose resin, a polyethylene resin, a polyester resin, a polyvinyl chloride resin, a polyacetal resin, a polyvinyl alcohol resin, and a chlorinated polyethylene resin. Any of various rubber-based materials such as resin-based materials, ruthenium rubber, acrylic rubber, nitrile rubber, and butyl rubber, and non-woven fabrics, polyester fibers, and acrylic fibers. The selection of organic materials is appropriately selected according to the purpose. Just fine. The above organic substance has a function of bonding, imparting plasticity, and insulating peeling of alloy powders. Further, in order to increase the flexibility of the noise suppression sheet, a plasticizer such as dioctyl phthalate may be added as needed. Further, in order to improve the compatibility between the soft magnetic alloy powder and the organic substance, a surface modifier such as a decane coupling agent may be added. Further, in order to obtain flame retardancy, a flame retardant such as aluminum hydroxide, magnesium hydroxide or red phosphorus may be added as needed.

The mixing ratio of the soft magnetic alloy powder to the organic material is preferably adjusted so that the ratio of the soft magnetic alloy powder in the noise suppression sheet finally obtained is 70% or more and 90% or less by volume. When the ratio of the soft magnetic alloy powder is 70% or more, the magnetic permeability required for functioning as a noise suppressing sheet can be obtained. Further, by setting the ratio of the soft magnetic alloy powder to 90% or less, a noise suppressing sheet having flexibility can be obtained. In the case where the flat soft magnetic alloy powder is used as the noise suppression sheet in the related art, in order to secure the surface resistance of 10 ⁸ Ω/□ or more and the flexibility of the noise suppression sheet, it is necessary to make the flat soft. In the present invention, the volume fraction of the soft magnetic alloy powder can be increased to 70% or more and 90% or less. Thus, the surface resistance of 10 ⁸ Ω/□ or more and the softness of the noise suppression sheet can be ensured, and a high noise suppression effect can be obtained by increasing the volume ratio of the soft magnetic alloy powder.

The organic solvent is not particularly limited, and toluene, butyl acetate, ethyl acetate or the like can be used. The organic solvent evaporates in the subsequent step and is therefore not included in the noise suppression sheet.

As a molding method of the noise suppression sheet, a known or arbitrary method such as a calender roll method or a doctor blade method can be mentioned. For example, in the case of using the squeegee method, a slurry composed of a soft magnetic alloy powder, an organic substance, or an organic solvent is molded and dried into a sheet shape to prepare a molded body. This molded body has a structure in which a soft magnetic alloy powder close to a spherical shape is supported on a base material made of an organic material. However, the present invention is not particularly limited to the above-described molding method, and any or a known molding method can be used as long as it can produce a noise suppression sheet having a thickness of 0.5 mm or less. [Examples]

(Examples 1, 2 and Comparative Examples 1 and 2) In Examples 1, 2 and Comparative Example 1, a crystal phase represented by Fe ₈₅ Si _9.5 Al _5.5 expressed by mass % was produced by a water atomization method. The atomized alloy powder which is not subjected to flat processing. Further, in Comparative Example 2, the atomized alloy powder which was produced by the water atomization method and which was not composed of a crystal phase expressed by mass% of Fe ₈₅ Si _9.5 Al _5.5 was not subjected to flat processing, and was flattened by a grinder. In order to remove the processing stress accompanying the flat processing, a flat atomized alloy powder composed only of a crystal phase was produced by performing an annealing treatment at 650 ° C for 5 hours in an argon atmosphere. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 2 was the same as the atomized alloy powder used in Example 2.

Next, the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powders of Comparative Example 2 of Examples 1, 2 and Comparative Example 1 were respectively made such that the volume ratio of each alloy powder became each slurry. Each of the alloy powder, the acryl rubber, and the toluene was mixed in a manner of 70% or more and 80% or less of the whole to prepare a slurry. Next, each slurry was processed into a sheet-shaped molded body on a film of polyethylene terephthalate by a doctor blade method. Then, each of the sheet-shaped molded articles was subjected to hot press at 100 ° C for 1 minute under a pressure of 10 MPa to prepare a noise suppressing sheet having a thickness of 0.15 mm. In the mean value of the average particle diameter and the aspect ratio of each alloy powder, the ion-grinding and polishing surface of the cross section of each noise suppression sheet in the thickness direction is observed by SEM, and the method described above is used based on the image. Measurements were taken. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Examples 3 and 4 and Comparative Examples 3 and 4) In Examples 3 and 4 and Comparative Example 3, a liquid crystal phase method was used to prepare a crystal phase composed of only Fe ₉₄ Si ₆ expressed by mass%. A flat processed atomized alloy powder is applied. Further, in Comparative Example 4, the atomized alloy powder which was produced by the water atomization method and which was not composed of a crystal phase expressed as Fe ₉₄ Si ₆ by mass%, which was not subjected to flat processing, was subjected to the same operation as in Comparative Example 2. A flat atomized alloy powder composed only of a crystal phase was produced by the treatment. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 4 was the same as the atomized alloy powder used in Example 4.

Next, in each of Examples 3, 4 and Comparative Example 3, each of the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powder of Comparative Example 4 were used so that the volume ratio of each alloy powder became each slurry. A noise suppressing sheet having a thickness of 0.15 mm was produced in the same manner as in Example 1 in a manner of 70% or more and 80% or less of the whole. In addition, the average value of the average particle diameter and the aspect ratio of each alloy powder was measured by the same method as Example 1. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Examples 5 and 6 and Comparative Examples 5 and 6) In Examples 5 and 6 and Comparative Example 5, a liquid phase formed by only a mass phase expressed as Fe ₅₀ Ni ₅₀ was produced by a water atomization method. A flat processed atomized alloy powder is applied. Further, in Comparative Example 6, the atomized alloy powder which was produced by the water atomization method and which was not subjected to the flat processing of only the crystal phase expressed as Fe ₅₀ Ni ₅₀ by mass% was subjected to the same operation as in Comparative Example 2. A flat atomized alloy powder composed only of a crystal phase was produced by the treatment. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 6 was the same as the atomized alloy powder used in Example 6.

Next, the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powders of Comparative Example 6 of Examples 5, 6 and Comparative Example 5 were respectively made such that the volume ratio of each alloy powder became each slurry. A noise suppressing sheet having a thickness of 0.15 mm was produced in the same manner as in Example 1 in a manner of 70% or more and 80% or less of the whole. In addition, the average value of the average particle diameter and the aspect ratio of each alloy powder was measured by the same method as Example 1. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Examples 7 and 8 and Comparative Examples 7 and 8) In Examples 7, 8 and Comparative Example 7, an amorphous phase represented by Fe _90.1 Si _6.1 B _3.8 by mass % was produced by a water atomization method. An atomized alloy powder which is not subjected to flat processing. Further, in Comparative Example 8, the atomized alloy powder which was produced by the water atomization method and which was not composed of an amorphous phase expressed as Fe _90.1 Si _6.1 B _3.8 by mass %, which was not subjected to flat processing, was passed through a grinder. In the flat processing, in order to remove the processing stress associated with the flat processing, an annealing treatment at 430 ° C for 1 hour was performed in an argon atmosphere to prepare a flat atomized alloy powder composed only of an amorphous phase. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 8 was the same as the atomized alloy powder used in Example 8.

Next, the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powders of Comparative Example 8 of Examples 7 and 8 and Comparative Example 7 were respectively made so that the volume ratio of each alloy powder became each slurry. A noise suppressing sheet having a thickness of 0.15 mm was produced in the same manner as in Example 1 in a manner of 70% or more and 80% or less of the whole. In addition, the average value of the average particle diameter and the aspect ratio of each alloy powder was measured by the same method as Example 1. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Examples 9 and 10 and Comparative Examples 9 and 10) In Examples 9, 10 and Comparative Example 9, by the water atomization method, only a non-cobalt of Co _81.8 Fe _5.1 Si _10.1 B _3.0 was produced by mass%. An atomized alloy powder composed of a crystal phase which is not subjected to flat processing. Further, in Comparative Example 10, the atomized alloy powder which was produced by the water atomization method and which was not composed of an amorphous phase expressed by mass% of Co _81.8 Fe _5.1 Si _10.1 B _3.0 was subjected to grinding. The machine was subjected to flat processing, and in order to remove the processing stress associated with the flat processing, an annealing treatment at 500 ° C for 1 hour was performed in an argon atmosphere to prepare a flat atomized alloy powder composed only of an amorphous phase. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 10 was the same as the atomized alloy powder used in Example 10.

Next, the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powders of Comparative Example 10 of Examples 9, 10 and Comparative Example 9 were respectively made such that the volume ratio of each alloy powder became each slurry. A noise suppressing sheet having a thickness of 0.15 mm was produced in the same manner as in Example 1 in a manner of 70% or more and 80% or less of the whole. In addition, the average value of the average particle diameter and the aspect ratio of each alloy powder was measured by the same method as Example 1. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Examples 11 and 12 and Comparative Examples 11 and 12) In Examples 11, 12 and Comparative Example 11, by water atomization, only Fe _83.3 Si _7.7 B _2.0 Nb _5.7 Cu _{1.3 was} produced by mass %. After the atomized alloy powder which is not subjected to the flat processing, which is formed of an amorphous phase, is subjected to a heat treatment at 540 ° C for 1 hour in an argon atmosphere, whereby the atomized alloy powder which is not composed of an amorphous phase and which is not subjected to flat processing is formed. In the middle, microcrystals composed of α-Fe were precipitated, and an atomized alloy powder having an amorphous phase and a crystal phase which was not subjected to flat processing was produced. Further, in Comparative Example 12, the atomized alloy powder which was produced by the water atomization method and which was not composed of an amorphous phase expressed by mass% of Fe _83.3 Si _7.7 B _2.0 Nb _5.7 Cu _1.3 was passed through. The attritor was subjected to flat processing to produce a flat atomized alloy powder composed only of an amorphous phase. Then, after heat treatment at 540 ° C for 1 hour in an argon atmosphere, microcrystals composed of α-Fe are precipitated in a flat atomized alloy powder composed only of an amorphous phase, thereby producing amorphous A flat atomized alloy powder of a phase and a crystalline phase. It should be noted that the atomized alloy powder before the flat processing used in Comparative Example 12 was the same as the atomized alloy powder used in Example 12.

Next, the atomized alloy powders which were not subjected to the flat processing and the flat atomized alloy powders of Comparative Example 12 of Examples 11 and 12 and Comparative Example 11 were respectively used so that the volume ratio of each alloy powder became each slurry. A noise suppressing sheet having a thickness of 0.15 mm was produced in the same manner as in Example 1 in a manner of 70% or more and 80% or less of the whole. In addition, the average value of the average particle diameter and the aspect ratio of each alloy powder was measured by the same method as Example 1. The average particle diameter and the average aspect ratio of each alloy powder are shown in Table 1.

(Evaluation Method) The surface resistance of each of the noise suppression sheets produced in each of the examples and the comparative examples was measured using a Hiresta-UP manufactured by Mitsubishi Chemical Corporation. The measurement results are shown in Table 1. Further, the mutual decoupling ratio of each noise suppression sheet was measured in accordance with the IEC standard (IEC62333-2). The measurement results are shown in Figures 1 to 6.

[Table 1]

(Description of Evaluation Results) The average value of the aspect ratio when the atomized alloy powder which was not subjected to the flat processing was used was in the range of 1.00 or more and 1.30 or less. That is, it is understood that the shape of the atomized alloy powder which is not subjected to the flat processing is closer to a spherical shape than the shape of the flat atomized alloy powder. Further, any of the noise suppression sheets exhibits a surface resistance value higher than 10 ⁸ Ω/□, which satisfies the surface resistance characteristics as a noise suppression sheet.

Next, regardless of the composition of the soft magnetic alloy powder, in Comparative Examples 2, 4, 6, 8, 10, and 12 in which the flat atomized alloy powder was used, the frequency at which the mutual decoupling ratio became 0 dB was 1.0~. The range of 1.5GHz. On the other hand, in Examples 1 to 12 in which alloy powder having an average particle diameter of 12 μm or less and an average aspect ratio of 1.00 or more and 1.30 or less was not subjected to flat processing, regardless of the composition of the soft magnetic alloy powder, The frequency at which the mutual decoupling ratio becomes 0 dB is higher than 1.5 GHz, and the mutual decoupling property can be made high frequency.

Next, in Comparative Examples 1, 3, 5, 7, 9, and 11 in which the alloy powder which was not subjected to the flat processing having an average particle diameter of 12 μm was used, the average value of the aspect ratio of the soft magnetic alloy powder was 1.00 or more. Further, in the range of 1.30 or less, regardless of the composition of the soft magnetic alloy powder, the frequency at which the mutual decoupling ratio becomes 0 dB is located on the low frequency side as compared with Examples 1 to 12. In the examples 1, 3, 5, 7, 9, and 11 in which the average particle diameter is 5 μm or less and the average value of the aspect ratio is 1.00 or more and 1.30 or less, the alloy powder which is not subjected to the flat processing is used. Regardless of the composition of the soft magnetic alloy powder, the frequency at which the mutual decoupling ratio becomes 0 dB is higher than that of the examples 2, 4, 6, 8, 10, and 12.

Next, Examples 7 to 10 using an alloy powder which is not only subjected to flat processing, which is composed only of an amorphous phase, and Example 11 using an alloy powder which has an amorphous phase and a crystal phase and which is not subjected to flat processing, In the case of 12, regardless of the composition of the soft magnetic alloy powder, the frequency at which the mutual decoupling ratio became 0 dB exceeded 2 GHz, and the frequency was higher than that of Examples 1 to 6 in which only the alloy powder composed of the crystal phase was used. [Industrial availability]

According to the present invention, it is possible to provide a near-field noise suppression sheet which can cope with high frequency decoupling properties even if the thickness of the noise suppression sheet is reduced.

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1 is a graph showing the frequency dependence of mutual decoupling ratios in Examples 1 and 2 and Comparative Examples 1 and 2. Fig. 2 is a graph showing the frequency dependence of the mutual decoupling ratios of Examples 3 and 4 and Comparative Examples 3 and 4. Fig. 3 is a graph showing the frequency dependence of the mutual decoupling ratios of Examples 5 and 6 and Comparative Examples 5 and 6. 4 is a graph showing the frequency dependence of mutual decoupling ratios of Examples 7 and 8 and Comparative Examples 7 and 8. Fig. 5 is a graph showing the frequency dependence of mutual decoupling ratios of Examples 9 and 10 and Comparative Examples 9 and 10. Fig. 6 is a graph showing the frequency dependence of mutual decoupling ratios of Examples 11 and 12 and Comparative Examples 11 and 12.

Claims (8)

A near-field noise suppression sheet, comprising: a substrate made of an organic substance; and a soft magnetic alloy powder carried in the substrate, wherein the soft magnetic alloy The powder has an average particle diameter of 12 μm or less, and an average value of the aspect ratio is 1.00 or more and 1.30 or less. The near-field noise suppression sheet according to claim 1, wherein the soft magnetic alloy powder is selected from an alloy powder composed only of an amorphous phase and an alloy powder having an amorphous phase and a crystalline phase. More than one alloy powder composition. The near-field noise suppression sheet according to the second aspect of the invention, wherein the soft magnetic alloy powder includes one or more alloy powders selected from the group consisting of Fe-based alloy powders and Co-based alloy powders. The near-field noise suppression sheet according to the third aspect of the invention, wherein the total concentration of Fe and Co in the one or more alloy powders selected from the Fe-based alloy powder and the Co-based alloy powder is 83% by mass or more. The near-field noise suppression sheet according to the first aspect of the invention, wherein the soft magnetic alloy powder is composed of an alloy powder composed only of a crystal phase. The near-field noise suppression sheet according to any one of the first to fifth aspect, wherein the soft magnetic alloy powder has an average particle diameter of 5 μm or less. The near-field noise suppression sheet according to any one of claims 1 to 5, wherein the surface resistance is 10 ⁸ Ω/□ or more. The near-field noise suppression sheet according to any one of claims 1 to 5, wherein the thickness is 0.5 mm or less.