阅读说明：本技术 磁性合金粉及其制造方法、线圈部件和电路板 (Magnetic alloy powder, method for producing same, coil component, and circuit board ) 是由 织茂洋子 柏智男 于 2020-02-26 设计创作，主要内容包括：本发明提供磁性合金粉及其制造方法、线圈部件和电路板。磁性合金粉由合金相(1)被氧化膜(2)覆盖的磁性颗粒(100)构成,将上述合金相(1)形成为Fe的含量为98质量％以上并且含有Si和至少一种比Fe容易氧化的Si以外的元素(M元素)的合金相,上述氧化膜(2)形成为,在膜厚方向的元素分布中,在以质量比例表示的Si的含量成为最大的部位的该Si的含量比在该部位的Fe的含量和上述M元素的含量分别都多。本发明的磁性合金粉,其金属中的Fe的含量多且绝缘性优异。(The invention provides a magnetic alloy powder, a method for producing the same, a coil component and a circuit board. The magnetic alloy powder is composed of magnetic particles (100) in which an alloy phase (1) is covered with an oxide film (2), wherein the alloy phase (1) is formed as an alloy phase containing Si and at least one element (M element) other than Si which is more easily oxidized than Fe, and the content of Fe in a portion where the content of Si is the largest in terms of mass ratio in an element distribution in a film thickness direction is larger than the content of Fe and the content of M element in the portion. The magnetic alloy powder of the present invention has a high Fe content in the metal and is excellent in insulation properties.)

1. A magnetic alloy powder characterized by:

consists of magnetic particles with alloy phase covered by oxide film,

the alloy phase contains Fe in an amount of 98 mass% or more, and contains Si and at least one M element other than Si which is more easily oxidized than Fe,

in the element distribution in the film thickness direction of the oxide film, the content of Si in a portion where the content of Si expressed by mass ratio is maximum is larger than the content of Fe and the content of the M element in the portion.

2. A magnetic alloy powder as claimed in claim 1, wherein:

in the oxide film, the total content of Si is greater than the total content of Fe and the total content of the M element, respectively.

3. A magnetic alloy powder as claimed in claim 1 or 2, wherein:

the oxide film contains the M element.

4. A magnetic alloy powder as claimed in any one of claims 1 to 3, wherein:

the oxide film contains Si and all of the M element contained in the alloy phase in the entire film.

5. The magnetic alloy powder according to any one of claims 1 to 4, wherein:

the M element is Cr, Al, Ti, Zr or Mg.

6. The magnetic alloy powder according to any one of claims 1 to 5, wherein:

the M element contains Cr.

7. A method for producing a magnetic alloy powder, characterized by comprising:

the magnetic alloy powder is composed of magnetic particles with alloy phases covered by oxide films,

the method for manufacturing the magnetic alloy powder comprises the following steps:

a step of preparing a raw material powder of a magnetic alloy containing 96.5 to 99 mass% of Fe and containing Si and at least one M element other than Si that is more easily oxidized than Fe; and

a step of obtaining a magnetic alloy powder by heat-treating the raw material powder to form an oxide film on the surface of each particle constituting the raw material powder,

in the magnetic alloy powder, the magnetic alloy powder is prepared by mixing the magnetic alloy powder,

the Fe content in the alloy phase is higher than that of the raw material powder, and

in the element distribution in the film thickness direction in the oxide film, the content of Si in a portion where the content of Si expressed by mass ratio is maximum is larger than the content of Fe and the content of the M element in the portion.

8. The method for producing a magnetic alloy powder according to claim 7, wherein:

in the oxide film of the magnetic alloy powder, the total content of Si is greater than the total content of Fe and the total content of the M element, respectively.

9. The method for producing a magnetic alloy powder as claimed in claim 7 or 8, wherein:

the content of Fe in the alloy phase is 98 mass% or more.

10. The method for producing a magnetic alloy powder as claimed in any one of claims 7 to 9, wherein:

the heat treatment is carried out at 600 to 850 ℃ for 4 hours or longer in an atmosphere having an oxygen concentration of 5 to 500 ppm.

11. The method for producing a magnetic alloy powder as claimed in any one of claims 7 to 10, wherein:

the heat treatment is performed so that the oxide film contains the M element.

12. The method for producing a magnetic alloy powder as claimed in any one of claims 7 to 11, wherein:

the heat treatment is performed so that the entire film of the oxide film contains Si and all of the M element contained in the alloy phase.

13. The method for producing a magnetic alloy powder as claimed in any one of claims 7 to 12, wherein:

the M element is Cr, Al, Ti, Zr or Mg.

14. The method for producing a magnetic alloy powder as claimed in any one of claims 7 to 13, wherein:

the M element contains Cr.

15. A coil component characterized by:

comprising a coil portion composed of a metal conductor and a magnetic base containing magnetic alloy particles,

the magnetic alloy particles are the magnetic alloy particles constituting the magnetic alloy powder according to any one of claims 1 to 6.

16. A circuit board, characterized by:

the coil component according to claim 15 is mounted on the circuit board.

Technical Field

The present invention relates to a magnetic alloy powder and a method for producing the same, and a coil component produced from the magnetic alloy powder and a circuit board on which the coil component is mounted.

Background

In recent years, with the increase in performance of electric and electronic devices, coil components such as inductors are required to have improved performance and smaller size. Since the performance of the coil component is affected by the amount of the magnetic material contained, the magnetic material is required to have high performance in order to achieve both miniaturization and high performance of the component, which are associated with a reduction in the amount of the magnetic material contained.

In a portion of the coil component through which a relatively large current flows, it is required to reduce a change in inductance due to the current. In order to meet this demand, a method of using a metal containing Fe as a main component as a magnetic material is widely used.

Since a metal material containing Fe as a main component has electrical conductivity, when a magnetic body is formed by molding a powder thereof, it is necessary to electrically insulate particles constituting the powder from each other. Therefore, a step of forming an insulating coating film on the surface of each particle constituting the metal material powder is performed.

For example, patent document 1 discloses that: a metal magnetic powder having a composition of 9.4% by weight of Si, 5.2% by weight of Al and the balance Fe is subjected to an oxidation treatment in an oxygen-nitrogen mixed gas atmosphere having an oxygen concentration of 2% by volume at 850 ℃ for 1 hour to form an insulating oxide film or the like.

Further, patent document 2 discloses the following technical idea: a silicone resin layer is formed on the surface of a particle of pure iron powder, and after molding, heat treatment is performed at a temperature of 600 to 650 ℃ in a non-oxidizing atmosphere, thereby forming an insulating coating on the surface of the particle.

Patent document 3 discloses the following: the atomized Fe-1% Si alloy particles were subjected to oxidation reaction at 450 ℃ for 2 hours in an atmosphere of very low oxygen concentration in which water vapor was mixed into nitrogen gas to have a relative humidity of 100% (normal temperature), and as a result, SiO was formed on the particle surface to have a film thickness of 5nm₂An insulating nano-film composed of an oxide film.

Disclosure of Invention

Technical problem to be solved by the invention

As shown in patent document 1, when an insulating film is formed by heat-treating a metal magnetic powder in an oxidizing atmosphere, it is necessary to contain an element other than Fe, such as Al, in a certain amount in the metal. Therefore, the content of Fe in the metal becomes relatively small, and there is a problem that sufficient magnetic characteristics cannot be obtained.

On the other hand, as shown in patent document 2, when a metal magnetic powder containing a large amount of Fe such as pure iron is used, it is relatively difficult to form an insulating film by oxidation of components in the metal, and therefore it is necessary to form an insulating film by another method such as coating the surface of the metal particles. Therefore, the insulating coating is formed thick, and the distance between the metal particles is increased by the thickness of the insulating coating during molding, which causes a problem of deterioration in magnetic properties. In addition, there is also a problem that: problems such as peeling or chipping of the insulating coating film occur during molding because the bonding strength between the metal particles and the insulating coating film is low; and the cost of the covering process becomes high.

Further, as shown in patent document 3, when Si, which is a component other than Fe contained in a small amount in a metal, is oxidized in a weakly oxidizing atmosphere to form an insulating film, SiO is used as a material for forming the insulating film₂Since the oxide film is thin and brittle, peeling or cracking may occur during handling, exposing the metal portion, and reducing the insulation properties. In addition, since the metal portion is exposed to the atmosphere, it reacts with oxygen and is easily oxidized, which also causes a decrease in magnetic characteristics. Therefore, the pressure applied during the production of the molded article is limited, and it is difficult to achieve both insulation and filling factor.

Accordingly, an object of the present invention is to provide a magnetic alloy powder having a high Fe content and excellent insulation properties, which can solve the above-described problems, and a simple production method thereof.

Technical solution for solving technical problem

The present inventors have conducted various studies to solve the above-described problems, and have found that the problems can be solved by heat-treating a magnetic alloy powder containing a very large amount of Fe and containing Si and an element other than Si which is more easily oxidized than Fe in the presence of oxygen to form a film of an oxide rich in Si on the surface of each particle constituting the magnetic alloy powder, and have completed the present invention.

That is, a first embodiment of the present invention for solving the above-mentioned problems is a magnetic alloy powder characterized in that: the magnetic particle is composed of magnetic particles in which an alloy phase is covered with an oxide film, wherein the alloy phase contains not less than 98 mass% of Fe, and contains Si and at least one M element, wherein the M element is an element other than Si which is more easily oxidized than Fe, and the Si content in a portion where the Si content is the largest in terms of mass ratio in an element distribution in a film thickness direction of the oxide film is larger than both the Fe content and the M element content in the portion.

A second embodiment of the present invention is a method for producing a magnetic alloy powder, including: the magnetic alloy powder is composed of magnetic particles with alloy phases covered by oxide films, and the method for producing the magnetic alloy powder comprises the following steps: a step of preparing a raw material powder of a magnetic alloy containing 96.5 to 99 mass% of Fe and containing Si and at least one M element other than Si that is more easily oxidized than Fe; and a step of obtaining a magnetic alloy powder by heat-treating the raw material powder to form an oxide film on the surface of each particle constituting the raw material powder, wherein the magnetic alloy powder has a higher content of Fe in the alloy phase than the raw material powder, and the content of Si in a portion where the content of Si expressed by mass ratio is largest in an element distribution in a film thickness direction in the oxide film is larger than the content of Fe and the content of the M element in the portion.

Effects of the invention

According to the present invention, a magnetic alloy powder having a high Fe content in the alloy and excellent insulation properties can be provided.

Drawings

Fig. 1 is a schematic view showing the structure of magnetic particles constituting the magnetic alloy powder according to the first embodiment of the present invention.

Fig. 2 is an explanatory diagram of a configuration example of the composite coil component according to the embodiment of the present invention.

Fig. 3 is an explanatory view of a configuration example of a wire-wound coil component according to an embodiment of the present invention, in which fig. 3 (a) is an overall perspective view, and fig. 3 (b) is an a-a sectional view of (a).

Fig. 4 is an explanatory diagram of a structural example of a laminated coil component according to an embodiment of the present invention, in which fig. 4 (a) is an overall perspective view, and fig. 4 (B) is a B-B sectional view of (a).

Fig. 5 is an explanatory diagram of a configuration example of the thin film coil component according to the embodiment of the present invention.

Fig. 6 is a graph showing the results of measuring the element distribution in the thickness direction of the oxide film in the magnetic alloy powder and the raw material powder of example 6, in which the solid line indicates the magnetic alloy powder and the broken line indicates the raw material powder.

Description of reference numerals

100 magnetic particles

1 alloy phase

2, oxidation film.

Detailed Description

The structure and the operation and effects of the present invention will be explained below while interposing the technical idea with reference to the drawings. However, the mechanism of action includes inference, and its correctness is not a limitation of the present invention. Among the components in the following embodiments, components that are not recited in the independent claims representing the uppermost concept can be described as arbitrary components. Note that the description of a numerical range (the description of connecting 2 numerical values by "-") means that the numerical values described as the lower limit and the upper limit are also included.

(magnetic alloy powder)

A magnetic alloy powder according to a first embodiment of the present invention (hereinafter, may be simply referred to as "first embodiment") is characterized by comprising magnetic particles 100 in which an alloy phase 1 is covered with an oxide film 2, as shown in fig. 1, the alloy phase 1 contains not less than 98 mass% of Fe and contains Si and at least one element other than Si which is more easily oxidized than Fe (hereinafter, may be referred to as "M element"), and the oxide film 2 contains, in an element distribution in a film thickness direction, a portion where the content of Si expressed by a mass ratio is maximum in the content of Si in the portion, the content of Si being larger than the content of Fe in the portion and the content of the M element.

The alloy phase 1 in the first embodiment contains not less than 98 mass% of Fe as a constituent element. Since the alloy phase portion contains a large amount of Fe, the magnetic material has excellent magnetic properties such as magnetic permeability when formed into a magnetic body. The content of Fe in alloy phase 1 is preferably 99 mass% or more.

The alloy phase 1 contains at least one M element in addition to Fe. Since the alloy phase 1 contains Si, the oxide film 2 having high electrical insulation and a smooth surface can be formed on the surface of the magnetic particle. Further, since the element M is contained, oxidation of Fe, which is a main component of the alloy phase 1, can be suppressed, and magnetic properties such as magnetic permeability are stabilized when the magnetic material is formed.

Examples of the M element include Cr, Al, Ti, Zr, and Mg. Among these elements, Cr or Al is preferable, and Cr is particularly preferable, in view of the high oxidation inhibiting effect of Fe.

The M element may be contained in the alloy phase 1 by only 1 kind, or may be contained by 2 or more kinds.

In the first embodiment, the magnetic particles 100 are formed by covering the alloy phase 1 with the oxide film 2.

In the oxide film 2 on the surface of the magnetic particle 100, in the element distribution in the film thickness direction, the content ratio of Si at a portion where the content of Si expressed by mass ratio becomes maximum is large, and the content of Fe and the content of M element at the portion are large, respectively. This means that the oxide film 2 has a thin layer containing Si most as a constituent element. Since such a thin layer has excellent insulating properties, the oxide film 2 and the magnetic particles 100 having such a thin layer exhibit high insulating properties.

The oxide film 2 on the surface of the magnetic particle 100 preferably has a large total content of Si, i.e., a large total content of Fe and a large total content of the M element. The oxide film 2 is rich in Si, and thus can obtain higher insulation.

The oxide film 2 preferably contains an M element. Since the oxide film 2 contains the element M, oxidation of Fe in the alloy phase 1 located inside thereof can be suppressed, and magnetic properties such as magnetic permeability are stabilized when the magnetic material is formed.

Here, the mass ratio of each element in the alloy phase 1 and the oxide film 2 was measured by a method in which the content ratio (atomic%) of each element including iron (Fe) constituting the surface of the magnetic particle of the magnetic alloy powder was measured by using an X-ray photoelectron spectrometer (ulivac-PHI, PHI Quantera II manufactured by incorporated), and the sputtering of the surface of the particle was repeated, whereby the distribution of each element in the depth direction (radial direction) of the particle was obtained, the content ratio of each element was measured, and a monochromatic AlK α ray was used as an X-ray source, and the detection region was set to 100 μm

Every 5 nm. In the sputtering conditions, argon (Ar) was used as a sputtering gas, the applied voltage was set to 2.0kV, and the sputtering rate was set to about 5nm/min (in terms of SiO)₂Value of (d). In the concentration distribution of Fe obtained by measurement: (Atomic%), the distance between the measurement points at which the concentration difference between the measurement points first becomes less than 1 atomic% is defined as the boundary between the alloy phase 1 and the oxide film 2 when viewed from the surface side of the particles. Then, the mass ratio (mass%) of the elements is calculated for the oxide film 2, which is a region shallower than the boundary, and the alloy phase 1, which is a region deeper than the boundary.

In the first embodiment, it is preferable that all of the elements contained in the alloy phase 1, of the Si and M elements, be contained in the entire oxide film 2. The case where these elements are contained in the entire oxide film 2 can be said to mean that the oxide film 2 is formed by diffusion of the components in the alloy phase 1. In the magnetic alloy powder having the oxide film 2 formed through this process, the distribution of each element in the particles constituting the powder is continuous from the inside of the particle to the outer peripheral surface of the particle, and therefore, the stress generated inside the particle can be reduced. This can suppress a decrease in the magnetic permeability of the particles themselves.

Here, it can be confirmed that all the elements contained in the alloy phase 1 of the Si and M elements are contained in the entire oxide film 2 as follows: in the distribution of the elements in the depth direction (radial direction) obtained by measuring the mass ratio of the elements in the alloy phase 1 and the oxide film 2, all the elements can be detected at all the measurement points located in the region where the oxide film 2 is formed.

In order to obtain magnetic particles 100 in which all elements contained in the alloy phase 1 of Si and M elements are contained in the entire oxide film 2, it is effective to heat-treat the raw material powder of the magnetic alloy in a low-oxygen atmosphere (approximately 5ppm to 500ppm or less), as described later. By forming such an oxidizing atmosphere, a drastic oxidation reaction can be suppressed. This can selectively oxidize an element that is more easily oxidized than Fe. In particular, as an element that is more easily oxidized than Fe, oxidation of Si can be promoted. Further, when an oxygen atmosphere is formed to be lower than this, although the same oxidation reaction can be obtained, the time required for the heat treatment is long, and the range in which oxygen can be supplied is easily limited, which causes unevenness of the oxidation reaction due to the presence or absence of contact between particles. For this reason, it is preferable to form a low-oxygen atmosphere as described above.

In the first embodiment, the oxide film 2 preferably has a thickness of 10nm or more. By making the thickness of the oxide film 210 nm or more, the electrical insulation between the magnetic particles 100 can be made higher. Further, even if the oxide film 2 is damaged during the treatment, the alloy phase 1 can be prevented from contacting the atmosphere, and oxygen in the atmosphere can be suppressed from reaching the metal portion by diffusion, whereby deterioration of the magnetic properties due to oxidation of Fe can be suppressed. The thickness of the oxide film 2 is more preferably 20nm or more.

The upper limit of the thickness of the oxide film 2 is not particularly limited, but is preferably 500nm or less. When the thickness of the oxide film 2 is 500nm or less, the smoothness of the surface of the oxide film 2 can be maintained. When the thickness is larger than 500nm, the ratio of components other than Si increases, and thus unevenness tends to occur on the surface. The thickness of the oxide film 2 is more preferably 200nm or less. By setting the thickness of the oxide film 2 to 200nm or less, the oxide film 2 can be prevented from being cracked or chipped due to collision of particles or the like during processing. In addition, when the magnetic material is formed, a high magnetic permeability can be obtained. The thickness of the oxide film 2 is more preferably 100nm or less. Further, the thickness of the oxide film 2 is more preferably 50nm or less from the viewpoint of improving the smoothness of the surface of the magnetic particles 100 to form a magnetic alloy powder having excellent fluidity.

Here, the thickness of the oxide film 2 is calculated by: the cross section of the magnetic grains 100 constituting the magnetic alloy powder was observed with a Scanning Transmission Electron Microscope (STEM) (JEM-2100F, manufactured by japan electronics corporation), the oxide film 2 was recognized from the difference in contrast (lightness) from the difference in composition of the alloy phase 1 inside the grains, and the thickness was measured at a magnification of 500,000 times at 10 sites of different grains to find an average value.

The particle size of the first embodiment is not particularly limited, and for example, the average particle size (median diameter (D) calculated from the particle size distribution measured on a volume basis can be used₅₀) ) is 0.5 to 30 μm. The average particle diameter is preferably 1 to 10 μm. The average particle diameter can be measured using a particle size distribution measuring apparatus using, for example, a laser diffraction/scattering method.

In the first embodiment, the specific surface area S (m)²Per g) and average particle diameter D₅₀The relationship (. mu.m) preferably satisfies the following formula (1).

(formula 1)

logS≤-0.98logD₅₀+0.34 (1)

The formula is based on the specific surface area S (m)²Per g) usual logarithm and average particle diameter D₅₀The common logarithm of (mum) is derived from the empirical rule of a linear relationship. The value of the specific surface area of the powder is affected not only by the irregularities on the surface of the particles constituting the powder but also by the particle size of the particles, and therefore it cannot be said that a powder having a small value of the specific surface area is composed of smooth particles having a small number of irregularities on the surface. Therefore, according to the above formula (1), the influence of the surface state of the particles on the surface area is separated from the influence of the particle diameter on the surface area, and the magnetic alloy powder having a small specific surface area due to the former influence is used as the magnetic alloy powder having a smooth surface with few irregularities. By reacting S with D₅₀Satisfies the above formula (1), and can be formed into a powder having more excellent flowability.

Specific surface area S (m)²Per g) and average particle diameter D₅₀The relationship of (μm) more preferably satisfies the following formula (2), and still more preferably satisfies the following formula (3).

(formula 2)

logS≤-0.98logD₅₀+0.30 (2)

(formula 3)

logS≤-0.98logD₅₀+0.25 (3)

Here, the specific surface area S is measured and calculated by a full-automatic specific surface area measuring device (mount tech co., ltd., Macsorb) using a nitrogen adsorption method. First, after the measurement sample is degassed in the heater, the measurement sample is adsorbed and desorbed with nitrogen gas to measure the adsorbed nitrogen amount. Next, the adsorbed amount of the monolayer was calculated using the BET1 point method from the obtained adsorbed nitrogen amount, and the surface area of the sample was calculated from this value using the area occupied by 1 nitrogen molecule and the value of the avergarro' snumber. Finally, the surface area of the obtained sample was divided by the mass of the sample to obtain the specific surface area S of the powder.

Further, the average particle diameter D₅₀The particle size distribution was measured and calculated by a particle size distribution measuring apparatus (LA-950, HORIBA, Ltd.) by laser diffraction/scattering method. First, water as a dispersant was put into a wet flow cell (flow cell), and a sufficiently pulverized powder was put into the cell at a concentration at which an appropriate detection signal can be obtained to measure the particle size distribution. Next, the median diameter in the obtained particle size distribution was calculated and taken as the average particle diameter D₅₀。

(method for producing magnetic alloy powder)

In the method for producing a magnetic alloy powder according to the second embodiment of the present invention (hereinafter, may be simply referred to as "second embodiment"), a raw material powder of a magnetic alloy containing 96.5 to 99 mass% of Fe and containing Si and at least one M element is prepared, and the raw material powder is subjected to a heat treatment to obtain a magnetic alloy powder composed of magnetic particles having an alloy phase covered with an oxide film. The magnetic alloy powder is formed such that the content ratio of Fe in the alloy phase is higher than that of the raw material powder, and the content ratio of Si in a portion where the content of Si expressed by mass ratio is maximum is higher in the element distribution in the film thickness direction in the oxide film than in the portion.

The raw material powder for the magnetic alloy used in the second embodiment contains 96.5 to 99 mass% of Fe as a constituent element. When the Fe content is 96.5 mass% or more, a magnetic alloy powder having an alloy phase with a high Fe content can be obtained by the heat treatment described later, and when a magnetic body is formed, the magnetic body having excellent magnetic properties such as magnetic permeability is obtained. The content of Fe is preferably 97 mass% or more. On the other hand, by setting the Fe content to 99 mass% or less, oxidation of Fe due to heat treatment described later can be suppressed, and a decrease in magnetic properties such as magnetic permeability can be suppressed. The content of Fe in the alloy phase is preferably 98 mass% or less.

The raw material powder contains not only Fe but also Si. Since the raw material powder contains Si, an oxide film rich in Si can be formed on the surface of the magnetic particles by heat treatment described later, and high electrical insulation can be obtained.

In addition, the raw material powder contains at least one M element. Since the raw material powder contains the M element, the M element diffuses on the surface of the magnetic particles by the heat treatment described later, and an oxide film containing the M element can be formed. This can suppress oxidation of Fe and suppress a decrease in magnetic properties such as magnetic permeability. The content of the element M is not particularly limited, but is preferably 0.2 mass% or more, and more preferably 0.5 mass% or more, from the viewpoint of effectively suppressing the oxidation of Fe.

Examples of the M element include Cr, Al, Ti, Zr, and Mg. Among these elements, Cr or Al is preferable, and Cr is particularly preferable, because of its high oxidation inhibiting effect on Fe.

The M element may be contained in the alloy phase by only one kind, or may be contained in 2 or more kinds.

The particle diameter of the raw material powder is not particularly limited, and for example, the average particle diameter (median diameter (D) calculated from the particle size distribution measured on a volume basis can be used₅₀) ) is 0.5 to 30 μm. The average particle diameter is preferably 1 to 10 μm. The average particle diameter can be measured using a particle size distribution measuring apparatus using a laser diffraction/scattering method, for example.

In the second embodiment, the raw powder is preferably heat-treated in an atmosphere having an oxygen concentration of 5ppm to 500 ppm. When the oxygen concentration is in this range, oxidation of Si can be promoted and oxidation other than Si can be suppressed. This enables the production of an oxide film containing a large amount of Si, and enables the formation of a surface state with few irregularities. Further, by setting the oxygen concentration in the heat treatment atmosphere to 5ppm or more, diffusion of Si into the magnetic particle surface can be promoted, and an oxide film rich in Si and excellent in electrical insulation can be formed. At the same time, the diffusion of the M element is promoted, and the oxidation of Fe in the alloy can be effectively suppressed by forming an oxide film containing the M element. The oxygen concentration in the heat treatment atmosphere is more preferably 50ppm or more, and still more preferably 100ppm or more. Further, since an oxide film having a smooth surface with few fine irregularities can be formed on the surface of the magnetic particles by performing the heat treatment in the low-oxygen atmosphere, the oxygen concentration in the heat treatment atmosphere is preferably 500ppm or less, more preferably 400ppm or less, and still more preferably 300ppm or less.

The heat treatment temperature of the raw material powder is preferably 600 ℃ or higher. When the heat treatment temperature is 600 ℃ or higher, Si is sufficiently diffused on the surface of each particle constituting the raw material powder, so that an oxide film having high electrical insulation properties can be formed, the content ratio of Fe in the alloy phase is increased, and magnetic properties such as magnetic permeability are improved. At the same time, the M element is sufficiently diffused to form an oxide film containing the element, whereby the oxidation of Fe in the alloy can be effectively suppressed. The heat treatment temperature is preferably 650 ℃ or higher, more preferably 700 ℃ or higher. The upper limit of the heat treatment temperature is not particularly limited, but is preferably 850 ℃ or less, more preferably 800 ℃ or less, and still more preferably 750 ℃ or less, from the viewpoint of suppressing excessive oxidation of Fe and obtaining a magnetic body having excellent magnetic properties.

The heat treatment time of the raw material powder is preferably 4 hours or more. By performing such heat treatment, oxidation of components other than Fe is promoted while suppressing oxidation of Fe, and the content of Fe with respect to the raw material powder can be increased. Therefore, the content ratio of Fe in the alloy phase increases, and the magnetic saturation characteristics can be improved. Further, Si is oxidized, but Si remains in the alloy phase, whereby the properties of magnetic permeability and loss can be maintained. This can be interpreted microscopically as: by the long-time heat treatment, Si and M elements contained in the raw material powder are sufficiently diffused on the surfaces of the magnetic particles, and the content ratio of Fe in the alloy phase increases, thereby improving magnetic properties such as magnetic permeability. The heat treatment time is preferably 5 hours or more, more preferably 10 hours or more. The upper limit of the heat treatment time is not particularly limited, but the heat treatment time is preferably 24 hours or less, more preferably 12 hours or less, from the viewpoint of improving productivity by completing the heat treatment in a short time.

The heat treatment in the second embodiment may be a batch process or a Flow process. As an example of the pipeline processing, there can be exemplified a method in which: a plurality of heat-resistant containers containing the raw material powder of the magnetic alloy are continuously and continuously charged into a tunnel kiln, and are allowed to pass through a region maintained at a predetermined atmosphere and temperature for a predetermined time.

According to the first and second embodiments described above, a magnetic alloy powder having a large Fe content and excellent insulation properties can be obtained. The magnetic alloy powder can be used to obtain a high-performance coil component. The coil component made of the magnetic alloy powder includes a coil portion that is a so-called Composite coil component, and a core portion in which the coil portion is embedded, the core portion being a portion containing the magnetic alloy powder and a resin, and the above-described advantages of the first and second embodiments are significant, and therefore, the coil component is formed as a component having excellent magnetic characteristics, durability, and reliability, and the component can be downsized. Further, the performance of a circuit board mounted with such a coil component can be improved and the circuit board can be miniaturized. Therefore, a composite coil component and a circuit board, which are preferred embodiments of the present invention, will be described below as a third embodiment and a fourth embodiment, respectively.

(coil component)

A coil component according to a third embodiment of the present invention (hereinafter, may be simply referred to as "third embodiment") is a coil component, characterized in that: the coil component includes a coil portion made of a metal conductor and a magnetic base containing magnetic alloy particles constituting the magnetic alloy powder of the first embodiment.

The coil portion may be disposed in the magnetic base. Alternatively, the magnetic material may be wound around the magnetic substrate.

The magnetic matrix contains magnetic alloy particles constituting the magnetic alloy powder of the first embodiment.

The structure of the magnetic matrix may contain a resin in addition to the magnetic alloy particles, and is a structure that can be conformed by the action of the resin. Further, the magnetic alloy particles may be bonded to each other by the oxide film to form a shape.

As a third embodiment, a composite coil component shown in fig. 2, a wire-wound coil component shown in fig. 3, a laminated coil component shown in fig. 4, a thin-film coil component shown in fig. 5, and the like are exemplified.

As a manufacturing method of the third embodiment, for example, in the case of a composite coil component, a coil component is typically obtained by mixing a magnetic alloy powder and a resin to prepare a mixture, then putting the mixture into a forming die such as a metal die in which an air core coil is arranged in advance, performing press forming, and then curing the resin.

The magnetic alloy powder used is described above, and therefore, the description thereof is omitted.

The resin used is not limited in kind as long as it can be molded and shape-retaining by bonding the particles of the magnetic alloy powder to each other, and various resins such as epoxy resin and silicone resin can be used. The amount of the resin used is not limited, and for example, 1 to 10 parts by mass may be used for 100 parts by mass of the magnetic alloy powder. In the second embodiment, when a magnetic alloy powder obtained by heat-treating a raw material powder in a low-oxygen atmosphere is used, the amount of resin used is preferably 3 parts by mass or less with respect to 100 parts by mass of the magnetic alloy powder, because the magnetic alloy powder has excellent fluidity and the proportion of the magnetic alloy powder can be increased by reducing the amount of resin used.

The mixing of the magnetic alloy powder and the resin and the charging method of the molding die with the charged mixture are not limited, and other than the method of charging the molding die with the mixture in a fluid state in which the two are mixed, a method of charging the molding die with the granulated magnetic alloy powder having the resin applied to the surface thereof may be used. Further, as a method of charging the mixture into a forming die together with press forming described later, a method of introducing the mixture formed into a sheet shape into a forming die by pressing may be employed.

The temperature and pressure for press molding are not limited, and may be appropriately determined depending on the material and shape of the air-core coil disposed in the mold, the fluidity of the magnetic alloy powder to be charged, the type and amount of the resin to be charged, and the like.

The curing temperature of the resin may be appropriately determined depending on the resin used.

The magnetic base according to the third embodiment may be formed by press-molding a mixture of the magnetic alloy powder and the resin, and then heat-treating the resultant molded body at a temperature higher than the curing temperature of the resin. In this case, the resin is decomposed due to the heat treatment, and an oxide film on the surface of the magnetic alloy particles grows, by which the magnetic alloy particles are bonded to each other. In addition, the resin component is substantially decomposed by the heat treatment, but carbon may remain locally.

The magnetic base thus obtained is wound to obtain a wound coil component. The wire-wound coil component is also an example of the coil component of the third embodiment.

When the coil component is a laminated coil component, the coil component can be produced by a sheet method. As a processing procedure of the flake method, first, a mixture is prepared by mixing a magnetic alloy powder and a resin, and then the mixture is coated into a flake shape by a doctor blade method or the like, and after cutting the flake, a through hole is formed at a predetermined position by a laser or the like, and an internal pattern is printed at the predetermined position. Next, these sheets are stacked in a predetermined order, and thermocompression bonding is performed to obtain a laminate. Next, the laminate is cut into individual parts in the size of each part by a cutter such as a cutter or a laser cutter, if necessary. Finally, the laminated body is subjected to a heat treatment to obtain a laminated coil component. The laminated coil component is also an example of the coil component of the third embodiment.

When the coil component is a thin film coil component, photolithography can be used. The thin film coil component is also an example of the third embodiment.

In addition to the above-described exemplary manufacturing methods, it is needless to say that known manufacturing methods corresponding to the shape of the coil component and the like can be adopted.

In the third embodiment, a magnetic alloy powder having a high Fe content and excellent insulating properties is used as the magnetic alloy powder, and thus a high-performance coil component is formed. Thus, the element volume required for obtaining the same inductance can be reduced, and therefore, the coil component can be miniaturized.

(Circuit board)

A circuit board according to a fourth embodiment of the present invention (hereinafter, may be simply referred to as "fourth embodiment") is a circuit board on which the coil component according to the third embodiment is mounted.

The structure of the circuit board and the like are not limited, and a circuit board corresponding to the purpose may be used.

In the fourth embodiment, by using the coil component of the third embodiment, high performance and miniaturization can be achieved.

(examples)

The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(example 1)

A raw material powder of a magnetic alloy having a composition of 96 mass% of Fe, 2 mass% of Si, 1 mass% of Cr and 1 mass% of Al and an average particle size of 4.0 μm was placed in a zirconia container and placed in a vacuum heat treatment furnace.

Subsequently, the furnace was evacuated to an oxygen concentration of 5ppm, the temperature was raised to 650 ℃ at a rate of 5 ℃/min, and the temperature was maintained for 5 hours to conduct heat treatment, and then the furnace was cooled to room temperature to obtain a magnetic alloy powder of example 1.

The mass ratios of the respective elements in the alloy phases of the magnetic particles constituting the magnetic alloy powder were measured by the above-described method, and the mass ratios of Fe, Si, Cr, and Al were 98.0 mass%, 1.0 mass%, and 0.8 mass%, respectively.

In addition, with respect to the obtained magnetic alloy powder, the mass ratios of the respective elements in the oxide films of the magnetic particles constituting the powder were measured by the above-described method, and it was confirmed that Si was contained most in the measurement position where the Si content became the maximum, and Cr and Al were contained in the measurement position.

The thickness of the oxide film formed on the surface of the magnetic particle was measured by the above-described method and found to be 20nm with respect to the obtained magnetic alloy powder.

(example 2)

A magnetic alloy powder of example 2 was obtained in this manner, except that the oxygen concentration of the atmosphere at the time of heat treatment was changed to 100ppm in the same manner as in example 1.

The mass ratios of the elements in the alloy phases of the magnetic particles constituting the obtained magnetic alloy powder were measured in the same manner as in example 1, and the mass ratios were 98.1% for Fe, 0.8% for Si, 0.7% for Cr, and 0.4% for Al.

In addition, with respect to the obtained magnetic alloy powder, the mass ratio of each element in the oxide film of the magnetic particles constituting the powder was measured by the same method as in example 1, and it was confirmed that the most contained element was Si at the measurement position where the Si content became the maximum, and that Cr and Al were contained at the measurement position.

The thickness of the oxide film formed on the surface of the magnetic particle was measured in the same manner as in example 1 and found to be 45nm with respect to the obtained magnetic alloy powder.

(example 3)

A magnetic alloy powder of example 3 was obtained in this manner, except that the retention time of the heat treatment was made 10 hours, in the same manner as in example 1.

The mass ratios of the elements in the alloy phases of the magnetic particles constituting the obtained magnetic alloy powder were measured in the same manner as in example 1, and the mass ratios were 98.3% for Fe, 1.7% for Si, 0.6% for Cr, and 0.4% for Al.

In addition, with respect to the obtained magnetic alloy powder, the mass ratio of each element in the oxide film of the magnetic particles constituting the powder was measured by the same method as in example 1, and it was confirmed that the most contained element was Si at the measurement position where the Si content became the maximum, and that Cr and Al were contained at the measurement position.

Comparative example 1

Raw material powder of a magnetic alloy having a composition of 96 mass% of Fe, 2 mass% of Si and 2 mass% of Cr and an average particle diameter of 4.0 μm was placed in a zirconia container and placed in a heat treatment furnace.

Subsequently, the temperature was raised to 650 ℃ at a rate of 5 ℃/min in the air atmosphere, and the resultant was heat-treated for 5 hours, after which the furnace was cooled to room temperature, to obtain a magnetic alloy powder of comparative example 1.

With respect to the obtained magnetic alloy powder, the mass ratio of each element in the alloy phase of the magnetic particles constituting the same was measured by the above-described method, and Fe was 97.3 mass%, Si was 1.8 mass%, and Cr was 0.9 mass%.

In addition, with respect to the obtained magnetic alloy powder, the mass ratios of the respective elements in the oxide films of the magnetic particles constituting the powder were measured by the same method as in example 1, and it was confirmed that the most contained element was Cr at the measurement position where the Si content became the maximum, and that Si was contained at the measurement position.

Comparative example 2

A magnetic alloy powder of comparative example 2 was obtained in the same manner as in example 3, except that a raw material powder having a composition of 98 mass% Fe and 2 mass% Si and an average particle diameter of 4.0 μm was used as the raw material powder of the magnetic alloy.

The thickness of the oxide film formed on the surface of the magnetic particle was measured in the same manner as in example 1, and found to be 320 nm. In the present comparative example, since the M element is not contained in the raw powder, it can be understood that Si is oxidized in the heat treatment, and an oxide film is formed thickly.

From the comparison of the compositions of the raw material powders and the magnetic alloy powders of examples 1, 2, and 3, it is judged that the mass ratio of Fe in the alloy phase increases by the heat treatment, whereas the mass ratio of Si, Cr, or Al decreases. In the oxide film formed on the surface of the magnetic grains constituting the magnetic alloy powder, since the mass ratio of Si, Cr, or Al is higher than that of the alloy phase, it can be said that Si, Cr, or Al in the alloy phase diffuses to the surface of the magnetic grains by the heat treatment to form an oxide.

The magnetic alloy powder in the present example can be said to form a coil component with a small change in inductance with respect to current, because the mass ratio of Fe in the alloy phase of the magnetic particles is high. Further, since the Si-rich oxide film is formed on the surface of the magnetic particle, the magnetic alloy powder of the present embodiment can be said to be excellent in insulating properties. Further, the magnetic alloy powder of the present example can be said to be excellent in oxidation resistance because Cr or Al as an M element is contained in the oxide film. In fact, after the magnetic alloy powder of the present example was left to stand in the atmosphere for several days, the composition of the magnetic particles and the thickness of the oxide film were measured, and no change was confirmed.

Example 4 (evaluation of coil component)

The magnetic alloy powder of example 1 was mixed with a resin to form a mixture, the mixture was filled into a forming die in which an air-core coil was disposed, and after press-forming, the resin was cured by heating to obtain a magnetic body. An electrode is formed on the surface of the magnetic body, and the coil component is formed by conducting the electrode to the coil.

The obtained coil component has a high specific permeability and saturation magnetic flux density and excellent insulation properties, as expected from the structure of the magnetic particles constituting the magnetic alloy powder, that is, the structure in which the mass ratio of Fe in the alloy phase is high and the Si-rich oxide film is formed on the particle surface.

(example 5)

In order to examine the influence of the heat treatment temperature on the element distribution of the magnetic particles, in examples 5 and 6, magnetic alloy powders were produced while changing the heat treatment temperature of the raw material powder.

A magnetic alloy powder of example 5 was obtained in this manner, except that the heat treatment temperature was set to 700 ℃.

The mass ratios of the elements in the alloy phases of the magnetic particles constituting the obtained magnetic alloy powder were measured in the same manner as in example 1, and the mass ratios were 98.1% for Fe, 1.0% for Si, 0.7% for Cr, and 0.2% for Al.

In addition, with respect to the obtained magnetic alloy powder, the mass ratios of the respective elements in the oxide films of the magnetic particles constituting the powder were measured by the same method as in example 1, and it was confirmed that the most contained element was Si at the measurement position where the Si content became the maximum, and that Cr and Al were contained at the measurement position.

(example 6)

A magnetic alloy powder of example 6 was obtained in this manner, except that the heat treatment temperature was set to 750 ℃.

The mass ratios of the elements in the alloy phases of the magnetic particles constituting the obtained magnetic alloy powder were measured in the same manner as in example 1, and the mass ratios were 98.3% for Fe, 1.1% for Si, 0.4% for Cr, and 0.2% for Al.

The mass ratios of the elements in the oxide films of the magnetic particles constituting the obtained magnetic alloy powder and the used raw material powder were measured by the same method as in example 1. The results are shown in fig. 6. In the figure, the results of the magnetic alloy powder of example 6 are shown by solid lines, and the results of the raw material powder used are shown by broken lines. From the results, it was confirmed that the content of Si in the element distribution in the film thickness direction was larger than that of Fe and M elements (the total amount of Cr and Al) at the measurement position (near 6nm from the surface) where the content of Si became maximum, and that the element was contained at the measurement position.

From the comparison of examples 1, 5, and 6, it was confirmed that the content ratio of Fe in the alloy phase of the magnetic particles increased as the heat treatment temperature became high. From this result, it can be said that the magnetic saturation characteristics can be improved by increasing the heat treatment temperature within a range in which Fe is not excessively oxidized to increase the Fe content in the alloy phase.

(example 7)

In the present example, it was confirmed that a magnetic alloy powder having a desired microstructure could be obtained even if the M element contained in the raw material powder was only 1 type.

A magnetic alloy powder of example 7 was obtained in the same manner as in example 1, except that a magnetic alloy having a composition of 96.5 mass% of Fe, 2 mass% of Si, and 1.5 mass% of Cr was used as the raw material powder.

The mass ratios of the elements in the alloy phases of the magnetic particles constituting the obtained magnetic alloy powder were measured in the same manner as in example 1, and Fe was 98.3 mass%, Si was 1.0 mass%, and Cr was 0.7 mass%.

In addition, with respect to the obtained magnetic alloy powder, the mass ratio of each element in the oxide film of the magnetic particles constituting the powder was measured by the same method as in example 1, and it was confirmed that the most contained element was Si at the measurement position where the Si content became the maximum, and Cr was contained at the measurement position.

Industrial applicability

The invention provides a magnetic alloy powder with high Fe content in alloy phase and excellent insulation property. The magnetic alloy powder is useful for forming a magnetic material having excellent magnetic properties and a high-performance coil component. In a preferred embodiment of the present invention in which the oxide film contains an M element, Fe in the alloy phase is not easily oxidized, and therefore, it is useful in that stable magnetic properties can be obtained.