JP2020038923A - Soft magnetic material composition, core, and coil-type electronic component - Google Patents

Abstract

To provide a soft magnetic material composition, a core, and a coil-type electronic component that can achieve a low core loss.SOLUTION: A soft magnetic material composition includes a plurality of soft magnetic alloy particles 21 and 22. The soft magnetic alloy particles contain an element M and iron. The element M has a stronger ionization tendency than silicon, and the maximum value of the mass ratio of silicon to the element M in regions 30 and 31 between the soft magnetic alloy particles is (Si/M), (Si/M)satisfies 1≤(Si/M)≤10.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a soft magnetic material composition, a core, and a coil-type electronic component.

  The metal magnetic material has an advantage that a higher saturation magnetic flux density can be obtained as compared with ferrite. As such a metal magnetic material, an Fe-Si-Al alloy, an Fe-Si-Cr alloy, and the like are known.

  Patent Document 1 proposes a coil-type electronic component using a magnetic material containing chromium, aluminum, and silicon and having improved magnetic permeability.

  Examples of the coil-type electronic component include an inductor, an EMC coil, and a transformer.

  In recent years, magnetic materials used in these coil-type electronic components have been required to further reduce core loss.

JP 2011-249774 A

  The present invention has been made in view of such circumstances, and has as its object to provide a soft magnetic material composition, a core, and a coil-type electronic component that can achieve low core loss.

In order to achieve the above object, the soft magnetic composition according to the present invention,
Having a plurality of soft magnetic alloy particles,
The soft magnetic alloy particles include an element M and iron,
The element M has a stronger ionization tendency than silicon,
When the maximum value of the mass ratio of silicon to the element M in the region between the soft magnetic alloy particles is (Si / M) _MAX ,
The (Si / M) _MAX satisfies 1 ≦ (Si / M) _MAX ≦ 10.

In the soft magnetic material composition according to the present invention, the soft magnetic alloy particles include the element M, and (Si / M) _MAX satisfies 1 ≦ (Si / M) _MAX ≦ 10, whereby the core loss can be reduced. .

Preferably, an amorphous layer is present at the (Si / M) _MAX .

The core loss can be reduced by the presence of the amorphous layer at (Si / M) _MAX .

Preferably, the element M is continuously present in a predetermined range including the location of (Si / M) _MAX ,
The predetermined range is a range of 50% or more of a distance between adjacent soft magnetic alloy particles.

(Si / M) The core loss can be reduced by the continuous presence of the element M in a predetermined range including the location of _MAX .

  Further, the core according to the present invention is composed of the soft magnetic material composition described in any of the above.

  Preferably, a coating layer is formed on at least a part of the surface of the core.

  A coil electronic component according to the present invention has the above-described core. The coil-type electronic component is not particularly limited, and examples thereof include electronic components such as an inductor, an EMC coil, and a transformer. In particular, it is suitable for miniaturized coil-type electronic components that can be surface-mounted on a circuit board.

FIG. 1 shows a core according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of the core shown in FIG. FIG. 3 is an enlarged cross-sectional view of a main part of the core, showing observation points when performing EDS analysis. FIG. 4 is a selected area diffraction pattern of the crystal lattice. FIG. 5 is a selected area diffraction pattern of the amorphous layer. FIG. 6 is a result of the EDS analysis of the fourth embodiment according to the embodiment of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  The core of the coil-type electronic component according to the present embodiment is a core (dust core) formed by dust molding. Powder compaction is a method in which a mold containing a soft magnetic alloy powder is filled in a mold of a press machine, pressurized at a predetermined pressure, and subjected to compression molding to obtain a compact.

  As the shape of the core (magnetic core) according to the present embodiment, in addition to the toroidal type shown in FIG. 1, FT type, ET type, EI type, UU type, EE type, EER type, UI type, drum type, pot Examples include a mold, a cup mold, and the like. By winding a single wire or a plurality of wires around the core, a desired coil-type electronic component can be obtained.

  The core for the coil-type electronic component according to the present embodiment is composed of a soft magnetic material composition.

  The soft magnetic material composition according to the present embodiment has a plurality of soft magnetic alloy particles 21 and 22, as shown in FIG. In the present embodiment, the region from one adjacent soft magnetic alloy particle 21 to the other soft magnetic alloy particle 22 is defined as regions 30 and 31 between the soft magnetic alloy particles.

  The soft magnetic alloy particles 21 and 22 according to the present embodiment include the element M and iron (Fe). Although not particularly limited, the soft magnetic alloy particles 21 and 22 according to the present embodiment may further include silicon (Si), carbon (C), or zinc (Zn).

  The element M has a stronger ionization tendency than silicon (Si). The element M has a tendency to form an oxide film on the surfaces of the soft magnetic alloy particles 21 and 22. Examples of the element M include chromium (Cr), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), manganese (Mn), and zinc (Zn). From the viewpoint of forming a uniform oxide film, chromium (Cr) or aluminum (Al) is preferable. Further, the element M is not limited to one kind, and a plurality of elements may be used.

  For example, when the element M is chromium (Cr), the soft magnetic alloy particles 21 and 22 according to this embodiment have a chromium (Cr) content of 1 to 9% by mass in terms of Cr and a silicon (Si) content of 0 to 0 in terms of Si. 9 mass%, with the balance being iron (Fe).

  In addition, for example, when the element M is aluminum (Al), the soft magnetic alloy particles 21 and 22 according to the present embodiment include aluminum (Al) in an amount of 1 to 9% by mass in terms of Al and silicon (Si) in an amount equivalent to Si. It is contained in an amount of 0 to 14% by mass, with the balance being iron (Fe).

The content of chromium (Cr) in the soft magnetic alloy particles 21 and 22 according to the present embodiment is preferably 1 to 9% by mass in terms of Cr. This makes it easier to keep (Si / M) _MAX within a predetermined range. From the above viewpoint, the content of chromium (Cr) in the soft magnetic alloy particles 21 and 22 is more preferably 3 to 7% by mass in terms of Cr.

The content of aluminum (Al) in the soft magnetic alloy particles 21 and 22 according to the present embodiment is preferably 1 to 9% by mass in terms of Al. This makes it easier to keep (Si / M) _MAX within a predetermined range. From the above viewpoint, the content of aluminum (Al) in the soft magnetic alloy particles 21 and 22 is more preferably 3 to 7% by mass in terms of Al.

  The content of silicon (Si) in the soft magnetic alloy particles 21 and 22 according to the present embodiment is preferably 0 to 9% by mass, and more preferably 2 to 8.5% by mass in terms of Si.

  The balance of the soft magnetic alloy particles 21 and 22 according to the present embodiment may be made of only iron (Fe).

  The soft magnetic material composition according to this embodiment may include components such as carbon (C) and zinc (Zn) in addition to the components of the soft magnetic alloy particles 21 and 22.

  The content of carbon (C) in the soft magnetic material composition according to the present embodiment is preferably less than 0.05% by mass, and more preferably 0.01 to 0.04% by mass.

  The content of zinc (Zn) in the soft magnetic material composition according to the present embodiment is preferably 0.004 to 0.2% by mass, and more preferably 0.01 to 0.2% by mass.

  The soft magnetic material composition according to the present embodiment may contain unavoidable impurities in addition to the above components.

  The average crystal particle diameter of the soft magnetic alloy particles 21 and 22 according to the present embodiment is preferably 4 to 60 μm. By setting the average crystal particle diameter in the above range, the core can be easily made thinner.

  Hereinafter, the mass of silicon (Si), element M or iron (Fe) with respect to the total mass of silicon (Si), element M, and iron (Fe) in regions 30, 31 between soft magnetic alloy particles 21 and 22 is described. "Ratio" is referred to as "3 element mass ratio".

  In the following, “oxygen (O), silicon (Si) with respect to the total mass of oxygen (O), silicon (Si), element M and iron (Fe) in regions 30 and 31 between soft magnetic alloy particles 21 and 22 will be described. The mass ratio of Si), element M, or iron (Fe) is referred to as “4 element mass ratio”.

In the present embodiment, the amorphous layer exists at the position of (Si / M) _MAX . Thereby, a soft magnetic material composition that can achieve low core loss can be obtained.

  From the above viewpoint, it is preferable that the Si-M oxide or the Si-M composite oxide, which is an amorphous layer, exists in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22.

  Note that the Si-M oxide is an oxide mainly composed of silicon (Si), the element M, and oxygen (O). The Si-M composite oxide is an oxide containing silicon (Si), the element M and oxygen (O), and further containing elements other than these three components (Si, M and O).

  Elements other than the three components (Si, elements M and O) contained in the Si-M composite oxide include vanadium (V), nickel (Ni), and copper (Cu).

  In the Si-M oxide, an element other than silicon (Si), the element M and oxygen (O) has a total of 0.1% with respect to the total mass of 100% by mass of the silicon (Si), the element M and oxygen (O). Less than 1% by mass is contained.

  Elements other than the three components (Si, elements M and O) contained in the Si-M oxide include vanadium (V), nickel (Ni), and copper (Cu).

  In the present embodiment, it is considered that the regions 30 and 31 between the soft magnetic alloy particles 21 and 22 contain silicon (Si) not derived from the elements contained in the soft magnetic alloy particles 21 and 22. Silicon (Si) not derived from the elements contained in the soft magnetic alloy particles 21 and 22 is not particularly limited, but is considered to be derived, for example, from silicon (Si) contained in the silicone resin used as the binder.

In this embodiment, when the maximum value of the mass ratio of silicon (Si) to the element M in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22 is (Si / M) _MAX , (Si / M) _MAX satisfies 1 ≦ (Si / M) _MAX ≦ 10. Thereby, a soft magnetic material composition that can achieve low core loss can be obtained.

Si-M oxide or Si-M composite oxide, which is an amorphous layer existing in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22, is formed in the region between the soft magnetic alloy particles 21 and 22 due to its randomness. It tends to contribute to the reduction of eddy current loss crossing 30, 30. Therefore, the (Si / M) _MAX is within a predetermined range, and the presence of the Si-M oxide or the Si-M composite oxide, which is an amorphous layer, at the (Si / M) _MAX places an eddy current. Loss is reduced, and core loss tends to be further reduced.

In the present embodiment, a method for calculating (Si / M) _MAX is not particularly limited, but a specific method will be described below.

  First, the soft magnetic alloy particles 21 and 22 and the regions 30 and 31 between the soft magnetic alloy particles 21 and 22 are determined by observing the cross section of the core using a scanning transmission electron microscope (STEM). Specifically, a cross section of the core is photographed by a STEM to obtain a bright field (BF) image. In this bright-field image, the regions present between the soft magnetic alloy particles 21 and 22 and the soft magnetic alloy particles 21 and 22 and having a contrast different from those of the soft magnetic alloy particles 21 and 22 are defined as the soft magnetic alloy particles 21 and 22. And the areas 30 and 31 between. The determination as to whether or not they have different contrasts may be made visually, or may be made by software or the like that performs image processing.

  Regarding the composition of the regions 30 and 31 between the soft magnetic alloy particles 21 and 22, as shown in FIG. 3, an arbitrarily selected observation line X is obtained by using an EDS device with sufficiently high resolution attached to the STEM. Perform EDS analysis. FIG. 6 shows the result of the EDS analysis of the present embodiment. In FIG. 6, the first vertical axis indicates the three element mass ratio, the second vertical axis indicates the Si / M mass ratio, and the horizontal axis indicates the distance from the starting point. Here, the “start point” is an arbitrary point in the soft magnetic alloy particles 21.

  In FIG. 6, the three element mass ratios of silicon (Si) are indicated by solid lines, the three element mass ratios of chromium (Cr) are indicated by dotted lines, and the three element mass ratios of iron (Fe) are indicated by alternate long and short dash lines. , And the Si / M mass ratio is indicated by a two-dot chain line.

  In FIG. 6, in a section where the distance from the starting point is 0 to 0.35 μm, the three element mass ratio of iron (Fe) is almost constant at around 95 wt%. This section is one soft magnetic alloy particle 21.

  In FIG. 6, in the section from 0.35 μm to 0.66 μm from the start point, the mass ratio of the three elements of iron (Fe) decreases, becomes almost constant around 0 wt%, and then increases. This section is a region 31 between the soft magnetic alloy particles 21 and 22.

  In FIG. 6, the section whose distance from the start point is 0.66 μm to 1.0 μm is almost constant again when the three element mass ratio of iron (Fe) is around 95 to 98 wt%. This section is the other soft magnetic alloy particles 22.

Then, (Si / M) _MAX in the region 31 between the soft magnetic alloy particles 21 and 22 is determined based on the obtained numerical values.

  Although not particularly limited, in the present embodiment, the four element mass ratio of oxygen (O) at the same position is 8 to 65% by mass, the four element mass ratio of silicon (Si) is 8 to 65% by mass, and When the four element mass ratio of the element M is 8 to 65% by mass, it is determined that the position is the Si-M oxide or the Si-M composite oxide.

  In addition, the mapping image of oxygen (O), the mapping image of silicon (Si), and the mapping image of element M are compared, and if oxygen (O), silicon (Si), and element M exist at the same position, For example, the position can be determined to be a Si-M oxide or a Si-M composite oxide.

  In the present embodiment, the method for determining whether or not the amorphous layer exists in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22 is not particularly limited. For example, a scanning transmission electron microscope (TEM) Alternatively, the determination may be made by analyzing a selected area diffraction pattern (SADP) in the reciprocal lattice space. In the selected area diffraction pattern, when the crystal has a regular crystal structure, each diffraction spot reflecting the crystal structure is observed as shown in FIG. On the other hand, in the case of an amorphous layer having no regular crystal structure, as shown in FIG. 5, a concentric circle centered on the center spot is observed. In the case of the amorphous layer, no clear diffraction spot other than the center spot is observed.

In the present embodiment, as shown in FIG. 6, it is preferable that the element M is continuously present in a predetermined range including the location of (Si / M) _MAX . Thereby, a soft magnetic material composition that can achieve low core loss can be obtained.

From the above viewpoint, it is preferable that silicon (Si) is continuous in a predetermined range including the location of (Si / M) _MAX .

  Here, the predetermined range is preferably a range of 50% or more of the distance between the adjacent soft magnetic alloy particles 21 and 22.

  In addition, that the element M is continuous in the predetermined range means that the three element mass ratio of the element M is preferably 8% by mass or more, more preferably 10% by mass or more in the predetermined range. Say.

  Further, that the silicon (Si) is continuous in the predetermined range means that the three element mass ratio of silicon (Si) is preferably 5% by mass or more, more preferably 8% by mass or more in the predetermined range. It means that.

  The length of the predetermined range is preferably 0.01 to 0.4 μm, more preferably 0.01 to 0.1 μm.

  A coating layer may be formed on at least a part of the surface of the core according to the present embodiment. Thereby, the core loss of the core can be further reduced.

The material of the coating layer is not particularly limited, and examples thereof include a glass composition, SiO ₂ , B ₂ O ₃ , ZrO _{2 and a} resin. Note that the coating layer may be composed of a plurality of materials, or may have a laminated structure composed of a plurality of layers.

  The coating layer is formed, for example, on at least a part of the surface of the core. The ratio of the formation of the coating layer to the surface area of the core (coverage) is preferably 50 to 100%. The higher the coverage, the greater the role of the protective layer for preventing chipping of the core. From the above viewpoint, the coverage is more preferably from 90 to 100%.

Next, an example of a method for manufacturing a core according to the present embodiment will be described.
The core of the present embodiment can be manufactured by firing a molded body containing a soft magnetic alloy powder and a binder (binder resin). Hereinafter, a preferred method of manufacturing the core of the present embodiment will be described in detail.

The manufacturing method according to the present embodiment is preferably
Mixing a soft magnetic alloy powder and a binder to obtain a mixture,
Drying the mixture to form a granulated powder;
Forming the mixture or granulated powder into the shape of the core to be produced, and obtaining a molded body,
Heating the obtained molded body to obtain a core.

  Further, a coating layer may be formed on the core.

  The core obtained by the manufacturing method according to the present embodiment is constituted by the soft magnetic material composition according to the present embodiment.

  As the soft magnetic alloy powder, alloy particles containing 1 to 9% by mass of chromium (Cr) in terms of Cr and 0 to 9% by mass of silicon (Si) in terms of Si, with the balance being iron (Fe). What is contained can be used.

  The shape of the soft magnetic alloy powder is not particularly limited, but is preferably spherical or ellipsoidal from the viewpoint of maintaining inductance even in a high magnetic field region. Among these, an ellipsoidal shape is desirable from the viewpoint of increasing the strength of the core.

  The average particle size of the soft magnetic alloy powder is preferably 3 to 80 μm. When the average particle size of the soft magnetic alloy powder is in the above range, the magnetic permeability is improved, eddy current loss is less likely to occur, and abnormal loss tends to be reduced. In addition, handling becomes easy. From the above viewpoint, the average particle size of the soft magnetic alloy powder is more preferably 5 to 20 μm.

  The soft magnetic alloy powder can be obtained by a method similar to a known method for preparing a soft magnetic alloy powder. At this time, it can be prepared using a gas atomizing method, a water atomizing method, a rotating disk method, or the like. Among these, a water atomizing method is preferable in order to easily produce a soft magnetic alloy powder having desired magnetic properties.

  As the binder, a material containing a silicone resin is used. By using a silicone resin as the binder, silicon (Si) not derived from the elements contained in the soft magnetic alloy particles 21 and 22 is effectively contained in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22. It is. As a result, an amorphous layer is easily formed in the regions 30, 31 between the soft magnetic alloy particles 21, 22.

  In addition, other binders may be included as long as the effects of the present invention are not impaired. Examples of other binders include various organic polymer resins, phenol resins, epoxy resins, water glass, and the like.

  As the binder, a silicone resin can be used alone or in combination with another binder. Since the content of carbon (C) in the soft magnetic material composition is preferably limited to less than 0.05% by mass, it is preferable to mainly use a silicone resin as the binder. When the content of carbon (C) in the soft magnetic material composition is within the above range, the strength of the obtained core can be improved.

  The amount of the binder added depends on the required properties of the core, but is preferably 0.2 to 10% by mass with respect to 100% by mass of the soft magnetic alloy powder. When the amount of the binder added is within the above range, an amorphous layer is easily formed in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22. From the above viewpoint, the addition amount of the binder is more preferably 0.5 to 6% by mass based on 100% by mass of the soft magnetic alloy powder.

  The addition amount of the silicone resin is preferably 0.2 to 8% by mass based on 100% by mass of the soft magnetic alloy powder. When the addition amount of the silicone resin is in the above range, an amorphous layer is easily formed in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22. From the above viewpoint, the addition amount of the silicone resin is more preferably 0.5 to 5% by mass based on 100% by mass of the soft magnetic alloy powder.

  Further, an organic solvent may be added to the mixture or the granulated powder, if necessary, as long as the effects of the present invention are not impaired.

  The organic solvent is not particularly limited as long as it can dissolve the binder, and examples thereof include various solvents such as toluene, isopropyl alcohol, acetone, methyl ethyl ketone, chloroform, and ethyl acetate.

  In addition, various additives, lubricants, plasticizers, thixotropic agents, and the like may be added to the mixture or the granulated powder, as long as the effects of the present invention are not impaired.

  Examples of the lubricant include aluminum stearate, barium stearate, magnesium stearate, calcium stearate, zinc stearate, and strontium stearate. These may be used alone or in combination of two or more. Among these, it is preferable to use zinc stearate as a lubricant from the viewpoint that so-called springback is small.

  When a lubricant is used, its amount is preferably 0.1 to 0.9% by mass based on 100% by mass of the soft magnetic alloy powder.

  In particular, when zinc stearate is used as a lubricant, the content of zinc (Zn) in the obtained soft magnetic material composition is in the range of 0.004 to 0.2% by mass. Adjustment is preferred. Thereby, the strength of the core tends to be better.

  The method for obtaining the mixture is not particularly limited, but is obtained by mixing a soft magnetic alloy powder, a binder and an organic solvent by a conventionally known method. In addition, you may add various additives as needed.

  At the time of mixing, for example, a mixer such as a pressure kneader, an atariter, a vibration mill, a ball mill, a V mixer, or a granulator such as a fluidized granulator or a tumbling granulator can be used.

  Further, the temperature and time of the mixing treatment are preferably about 1 to 30 minutes at room temperature.

  The method for obtaining the granulated powder is not particularly limited, and is obtained by drying the mixture by a known method.

  The temperature and time of the drying treatment are preferably from room temperature to about 200 ° C. for 1 to 60 minutes.

  If necessary, a lubricant may be added to the granulated powder. After adding the lubricant to the granulated powder, it is desirable to mix for 1 to 60 minutes.

  The method for obtaining the molded body is not particularly limited, and a known method is used. A molding die having a cavity of a desired shape is used. Preferably, the mixture is compression molded at a molding pressure of

  The molding conditions in the compression molding are not particularly limited, and may be appropriately determined according to the shape and size of the soft magnetic alloy powder and the shape, size and density of the dust core. For example, the maximum pressure is usually about 100 to 1000 MPa, preferably about 400 to 800 MPa, and the time for maintaining the maximum pressure is about 0.5 seconds to 1 minute.

  In the manufacturing method according to the present embodiment, since the binder contains the silicone resin, an amorphous layer is easily formed in the regions 30 and 31 between the soft magnetic alloy particles 21 and 22 constituting the core.

  The molding temperature is not particularly limited, but is usually preferably room temperature to about 200 ° C. This increases the density of the molded body and improves the performance of the obtained core.

  Next, the molded body obtained after molding is fired to obtain a core (firing step).

The holding temperature in the firing step is not particularly limited, but is usually preferably about 600 to 900 ° C. This makes it easier to keep (Si / M) _MAX within a predetermined range. From the above viewpoint, the holding temperature at the time of firing is preferably 700 to 850 ° C.

The rate of temperature rise in the firing step is not particularly limited, but it is preferable to achieve the holding temperature in a short time after the start of heating the molded body. Thus, by heating in a short time, (Si / M) _MAX can be easily set within a predetermined range.

  The heating method in the firing step is not particularly limited. For example, a thin and small-area container having good heat transfer is prepared, and a small number of the compacts (1 to 10) are sufficiently separated from the container. Put on. Specifically, adjacent compacts are placed 10 to 100 mm apart. Next, there is a method of directly putting the molded body together with the container into a furnace that has reached the holding temperature. In addition, there is also a method in which a heating body that has reached the holding temperature is sandwiched from above and below the molded body and directly placed in a furnace.

  The atmosphere in the firing step is not particularly limited, and the firing may be performed in an oxygen-containing atmosphere. Here, the oxygen-containing atmosphere is not particularly limited, but may be an air atmosphere (usually containing 20.95% of oxygen), or a mixed atmosphere with an inert gas such as argon or nitrogen. Can be Alternatively, the treatment may be performed under an inert gas such as argon or nitrogen.

  The holding time of the firing step is not particularly limited, and is, for example, 10 minutes to 5 hours.

  Next, a coating layer made of a glass composition, a binder resin and the like before heat treatment is formed on the surface of the core obtained as necessary.

  After the heat treatment, a coating layer is formed on the surface of the core.

  The core thus obtained can be used as a magnetic core.

(Si / M) _{MAX according} to the present embodiment is the composition of the soft magnetic alloy powder, the type or amount of the binder, the other additive components, the heating rate in the firing step, the holding temperature in the method of manufacturing the core. Alternatively, it can be controlled by the atmosphere or the like.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it is a matter of course that the present invention can be implemented in various modes without departing from the gist of the present invention. .

  For example, in the above-described embodiment, a core (compacted powder core) is manufactured by compacting a mixture or a granulated powder, but a core is produced by forming the mixture into a sheet and laminating the mixture. Is also good. Moreover, you may obtain a molded object by wet molding, extrusion molding, etc. other than dry molding.

  In the embodiment described above, a silicone resin is used as a binder in order to form a layer containing silicon (Si) at the grain boundary of the soft magnetic material composition. However, instead of the silicone resin, silica gel or an additive is used as an additive. A silicon (Si) -containing component such as silica particles may be used.

  In the above-described embodiment, the toroidal type core made of the soft magnetic material composition is shown. In addition, the soft magnetic material composition of the present embodiment may constitute the core in which the coil is embedded. it can. Specifically, the core in which the coil is embedded is a core that surrounds the coil and includes a soft magnetic material composition and a resin.

  The application of the core according to the present embodiment is not particularly limited, and can be suitably used as a core of various electronic components such as a coil-type electronic component, a switching power supply, a DC-DC converter, a transformer, and a choke coil. .

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1)
[Preparation of soft magnetic alloy powder]
Ingots, chunks (chunks), or shots (particles) of iron (Fe) alone, chromium (Cr) alone, and silicon (Si) alone were prepared. Next, they were mixed so as to have a composition of 4% by mass of chromium (Cr), 5% by mass of silicon (Si), and the balance of iron (Fe), and stored in a crucible arranged in a water atomizing apparatus. Next, the crucible was heated to 1600 ° C. or higher by high frequency induction using a work coil provided outside the crucible in an inert atmosphere, and the ingot, chunk or shot in the crucible was melted and mixed to obtain a melt.

  Next, a melt provided in the crucible is ejected from a nozzle provided in the crucible, and at the same time, a high-pressure (50 MPa) water stream collides with the ejected melt to rapidly cool the melt, thereby forming a soft magnetic material comprising Fe-Si-Cr-based particles. An alloy powder (average particle size; 11 μm) was produced.

  The composition of the obtained soft magnetic alloy powder was analyzed by a fluorescent X-ray analysis method.

[Preparation of core]
To 100% by mass of the obtained soft magnetic alloy powder, 4% by mass of a silicone resin (SR2414LV manufactured by Toray Dow Corning Silicone Co., Ltd.) was added, and these were mixed by a pressure kneader at room temperature for 30 minutes. The mixture was then dried in air at 150 ° C. for 20 minutes. To the soft magnetic alloy powder after drying, zinc stearate (Ninto Kasei: zinc stearate) was added as a lubricant, and mixed for 10 minutes by a V mixer. The addition amount of zinc stearate was 0.5% by mass with respect to 100% by mass of the soft magnetic alloy powder.

  Subsequently, the obtained mixture was molded into a toroidal sample having an outer diameter of 20 mm, an inner diameter of 10 mm, and a thickness of 5 mm to produce a molded body. The molding pressure was 600 MPa.

  The heating body reaching the holding temperature was sandwiched from above and below the molded body, and was placed in a furnace. In Tables 1 and 2, when the temperature of the molded body is increased by such a method, the column of "firing conditions" indicates "heated for a short time". The molded body was fired in the atmosphere at a holding temperature of 650 ° C. for 60 minutes to obtain a core.

(Examples 2 to 5 and Comparative Examples 3 and 4)
A core was obtained in the same manner as in Example 1 except that the holding temperature of the molded body was changed as shown in Table 1.

(Comparative Examples 1 and 2)
In Comparative Example 1, the temperature was raised to the holding temperature in 6 hours after the molded body was put in the furnace, and in Comparative Example 2, the temperature was raised to the holding temperature in 2 hours in the furnace. A core was obtained in the same manner as described above. In Comparative Examples 1 and 2, the heating body was not sandwiched from above and below the molded body.

(Examples 11 to 15 and Comparative Examples 13 and 14)
Using a simple substance of Al instead of a simple substance of Cr, a mixture of 91% by mass of iron (Fe), 5% by mass of aluminum (Al), and 4% by mass of silicon (Si) is mixed to form an Fe—Si—Al based A soft magnetic alloy powder (average particle size: 9 μm) composed of particles was prepared, and a core was obtained in the same manner as in Example 1 except that the holding temperature of the compact was changed as shown in Table 2.

(Comparative Examples 11 and 12)
In Comparative Example 11, the temperature of the compact was raised to the holding temperature over 6 hours in the furnace. In Comparative Example 12, the temperature of the compact was raised to the holding temperature over 2 hours in the furnace. A core was obtained in the same manner as described above. In Comparative Examples 11 and 12, the heating body was not sandwiched from above and below the molded body.

[Various evaluations]

<Confirmation of (Si / M) _MAX >
The cross section of the core was observed with a scanning transmission electron microscope (STEM) to determine “soft magnetic alloy particles” and “region between soft magnetic alloy particles”.

Next, as shown in FIG. 3, EDS analysis was performed on an observation line X arbitrarily selected using an EDS device provided with the STEM and having sufficiently high resolution. (Si / M) _MAX was determined based on the obtained numerical values. The results are shown in Tables 1 and 2. In particular, the results of Example 4 are shown in FIG. In FIG. 6, the first ordinate indicates the mass ratio of the three elements, the second ordinate indicates the mass ratio of Si / M, and the abscissa indicates the distance from the starting point.

<Confirmation of amorphous layer>
The presence of an amorphous layer was determined by analyzing a selected area diffraction pattern (SADP) in a reciprocal lattice space of a scanning transmission electron microscope (TEM).

<Core loss>
A copper wire was wound around the toroidal dust core sample for 10 turns, and the core loss was measured using an LCR meter (Hewlett-Packard 4284A). The measurement conditions were a measurement frequency of 1 MHz, a measurement temperature of 23 ° C., and a measurement level of 0.4 A / m. The results are shown in Tables 1 and 2.

From STEM observation and EDS analysis, (Si _{/ M) MAX} is Examples 1-5 is less than 0.5 super 10.6, Comparative Examples 1 to 3 and is (Si _{/ M) MAX} 10.6 or more (Si / M) It was confirmed that the core loss was lower than that of Comparative Example 4 in which _MAX was 0.5.

From the TEM observation, it was confirmed that Examples 1-4 have an amorphous layer at the position of (Si / M) _MAX . In Comparative Example 4, since the holding temperature was high, the soft magnetic alloy particles were partially melted and alloyed, and no amorphous layer was formed at the (Si / M) _MAX .

From STEM observation and EDS analysis, (Si _{/ M) MAX} is less than 0.7 Ultra 14.0 Examples 11 to 15 are Comparative Examples 11 to 13 and is (Si _{/ M) MAX} 14.0 or more (Si / M) It was confirmed that the core loss was lower than that of Comparative Example 14 in which _MAX was 0.7.

From TEM observation, it was confirmed that Examples 11 to 14 had an amorphous layer at (Si / M) _MAX . In Comparative Example 14, the soft magnetic alloy particles were partially melted and alloyed because the holding temperature was high, and no amorphous layer was formed.

From FIG. 6, it was confirmed that silicon (Si) and chromium (Cr) were continuously present in a predetermined range including (Si / M) _MAX of Example 4.

  In Example 4, it was confirmed by the following method whether or not silicon (Si) not derived from the element contained in the soft magnetic alloy particles was contained in the region between the soft magnetic alloy particles of the core. .

  In FIG. 6 (Example 4), most of chromium (Cr) is present in the region between the soft magnetic alloy particles, and hardly contained in the soft magnetic alloy particles. On the other hand, iron (Fe) is mostly present in the soft magnetic alloy particles, and is hardly contained in the region between the soft magnetic alloy particles.

  Therefore, it is considered that chromium (Cr) of the soft magnetic alloy powder moved to the region between the soft magnetic alloy particles and iron (Fe) of the soft magnetic alloy powder remained in the soft magnetic alloy particles during the manufacturing process of the core.

  Therefore, the mass ratio of iron (Fe) and silicon (Si) as the raw materials of the soft magnetic alloy powder and the mass ratio of iron (Fe) and silicon (Si) in the soft magnetic alloy particles in FIG. If so, it can be said that silicon (Si), which is the raw material of the soft magnetic alloy powder, has directly become silicon (Si) of the soft magnetic alloy particles. As a result, it can be said that silicon (Si) existing in the region between the soft magnetic alloy particles is not silicon (Si) derived from the raw material of the soft magnetic alloy powder, but silicon (Si) derived from the silicone resin.

  Then, as a result of the calculation, the mass ratio of iron (Fe) and silicon (Si) as the raw materials of the soft magnetic alloy powder and the mass ratio of iron (Fe) and silicon (Si) in the portion of the soft magnetic alloy particles in FIG. Were generally consistent. For this reason, it can be said that silicon (Si) existing in the region between the soft magnetic alloy particles is not silicon (Si) derived from the raw material of the soft magnetic alloy powder but silicon (Si) derived from the silicone resin.

  The core composed of the soft magnetic material composition according to the present invention can achieve low core loss.

21, 22, soft magnetic alloy particles 30, 31, regions between soft magnetic alloy particles

Claims (6)

Having a plurality of soft magnetic alloy particles,
The soft magnetic alloy particles include an element M and iron,
The element M has a stronger ionization tendency than silicon,
When the maximum value of the mass ratio of silicon to the element M in the region between the soft magnetic alloy particles is (Si / M) _MAX ,
(Si / M) _MAX is a soft magnetic material composition satisfying 1 ≦ (Si / M) _MAX ≦ 10. The soft magnetic material composition according to claim 1, wherein an amorphous layer exists at the (Si / M) _MAX . The element M is continuously present in a predetermined range including the (Si / M) _MAX portion,
The soft magnetic material composition according to claim 1, wherein the predetermined range is at least 50% of a distance between adjacent soft magnetic alloy particles.   A core comprising the soft magnetic material composition according to claim 1.   The core according to claim 4, wherein a coating layer is formed on at least a part of the surface of the core.   A coil-type electronic component having the core according to claim 4.

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