KR102040207B1 - Powder pressed magnetic body, magnetic core, and coil-type electronic component - Google Patents

Abstract

Provided are a compacted molded magnetic body, a magnetic core formed of the magnetic body, and a coil-type electronic component having the magnetic body, which are easy to manufacture, can stabilize quality, and have excellent insulation characteristics and low deterioration of magnetic properties. It is a compaction forming magnetic body containing the alloy particle 2 comprised from Fe-Si-Cr type soft magnetic alloy. Phosphorus is contained 40 to 100 ppm, and the Cr oxide film 4 containing phosphorus is formed on the surface of the alloy particles 2.

Description

Powder compacted magnetic material, magnetic core and coil type electronic component {POWDER PRESSED MAGNETIC BODY, MAGNETIC CORE, AND COIL-TYPE ELECTRONIC COMPONENT}

The present invention relates to a green compacted magnetic body, a magnetic core and a coil type electronic component.

In general, a magnetic core made of a conventionally formed compacted magnetic body having soft magnetic alloy particles has a problem of inferior insulation characteristics. Therefore, coating the surface of an alloy particle with a phosphate chemical conversion film etc., for example is examined (for example, patent document 1).

However, the technique of coating the surface of an alloy particle with a phosphate conversion film etc. has a subject that the manufacturing process number increases. In addition, there is also a problem that magnetic properties such as mu deteriorate by coating the surface of alloy particles.

Therefore, various countermeasures, such as mixing alloy particles having different particle diameters, have been used in combination. However, there is a fear that the quality of the magnetic body may become unstable and the manufacturing process is complicated.

Japanese Patent Publication No. 2008-63651

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and an object thereof is to provide a magnetic core composed of a compacted molded magnetic body and its magnetic body, which are easy to manufacture, can stabilize the quality, and have excellent insulation characteristics and low deterioration of magnetic properties. The branch provides a coiled electronic component.

In order to achieve the above object, the compacted compacted magnetic body according to the first aspect of the present invention is a compacted compacted magnetic body including alloy particles composed of Fe-Si-Cr-based soft magnetic alloy, and contains 40 to 100 ppm of phosphorus, A Cr oxide film containing phosphorus is formed on the surface of the alloy particles.

According to the green compacted magnetic body according to the first aspect of the present invention, since the Cr oxide film containing phosphorus is formed on the surface of the alloy particles, the insulating property is significantly improved as compared with the green compacted magnetic body containing no phosphorus. In addition, according to the green compacted magnetic body according to the first aspect of the present invention, it was confirmed by the present inventors that the deterioration of magnetic properties such as μ was different.

In addition, the green compacted magnetic body according to the first aspect of the present invention can be produced by simply including a predetermined amount of phosphorus in the soft magnetic alloy powder as a raw material and appropriately selecting heat treatment conditions. Therefore, manufacture is easy and quality can be stabilized.

In order to achieve the above object, the compacted compacted magnetic body according to the second aspect of the present invention is a compacted compacted magnetic body including alloy particles composed of Fe-Si-Cr-based soft magnetic alloy, and contains 40 to 100 ppm of phosphorus, Phosphorus is included in the grain boundaries between the alloy particles.

According to the green compacted magnetic body according to the second aspect of the present invention, since phosphorus is included in the grain boundaries of the alloy particles, the insulating property is significantly improved as compared with the green compacted magnetic body containing no phosphorus. Further, according to the green compacted magnetic body according to the second aspect of the present invention, it was confirmed by the present inventors that the deterioration of magnetic properties such as μ was different.

In addition, the green compacted magnetic body according to the second aspect of the present invention can be produced by simply including a predetermined amount of phosphorus in the soft magnetic alloy powder as a raw material and appropriately selecting heat treatment conditions. Therefore, manufacture is easy and quality can be stabilized.

The magnetic core according to the present invention is characterized by comprising the green compacted magnetic body described above.

The coiled electronic component according to the present invention has the magnetic core described above.

1 is a STEM image of a cross-section of a green compacted magnetic body according to one embodiment of the present invention.
2 is a graph showing changes in phosphorus content, insulation properties, and μi properties of the green compacted magnetic body according to the Examples and Comparative Examples of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on embodiment.

The magnetic core for coil type electronic components which concerns on this embodiment is a magnetic core which consists of a powder compacted magnetic body shape | molded by powder compaction. The compaction molding is a method of obtaining a molded body by filling a mold containing a soft magnetic alloy powder into a mold of a press machine, and pressing the mold at a predetermined pressure to perform compression molding.

As a shape of the magnetic core which concerns on this embodiment, besides a toroidal type, FT type, ET type, EI type, UU type, EE type, EER type, UI type, drum type, pot type, cup type, etc. can be illustrated. By winding the winding by a predetermined number of turns around the magnetic core, a desired coil type electronic component can be obtained.

The magnetic core for coil type electronic components which concerns on this embodiment is comprised from the green compacted magnetic body which concerns on this embodiment.

The green compacted magnetic body according to the present embodiment has a plurality of soft magnetic alloy particles 2 and grain boundaries 6 present between the soft magnetic alloy particles as shown in FIG. 1. The soft magnetic alloy particles 2 are composed of a Fe-Si-Cr based soft magnetic alloy.

In the Fe—Si—Cr based soft magnetic alloy, silicon is preferably contained in an amount of 0.1 to 9% by mass in terms of Si, and chromium in an amount of 0.1 to 15% by mass in terms of Cr, and the balance is composed of iron (Fe). More preferably, silicon is contained 1.4 to 9% by mass, particularly preferably 4.5 to 8.5% by mass, and chromium to 1.5 to 8% by mass, particularly preferably 3 to 7% by mass, in terms of Si, It is preferable that the balance consists of iron (Fe).

In the Fe-Ni-Si-Cr based soft magnetic alloy, 3 to 15 mass% of nickel in terms of Ni, 0.1 to 9 mass% of silicon in terms of Si, and 0.1 to 15 mass% of chromium in terms of Cr, It is preferable that it is comprised from iron (Fe). More preferably, 3 to 10% by mass of nickel in terms of Ni, 1.4 to 9% by mass of silicon in terms of Si, particularly preferably 4.5 to 8.5% by mass, and 1.5 to 8% by mass of chromium in terms of Cr, in particular Preferably it is 3-7 mass%, and it is preferable that remainder is comprised from iron (Fe).

Preferably the average crystal grain diameter of the soft magnetic alloy particle 2 which concerns on this embodiment is 30-60 micrometers. By making an average crystal grain diameter into the said range, thickness reduction of a magnetic core can be easily implement | achieved.

A Cr oxide film 4 is formed on the surface of the soft magnetic alloy particles 2. The Cr oxide film 4 is a phase containing oxygen and Cr, and may be a complex oxide containing elements other than Cr and oxygen, for example, Si. The Cr oxide film 4 may be a Si-Cr composite oxide phase having more Cr than the inside of the particles of the alloy particles 2. The Si-Cr composite oxide phase is not particularly limited, and examples thereof include an amorphous phase containing Si and Cr.

In addition, in the green compacted magnetic body according to the present embodiment, the oxide phase may further contain any one or both of Bi and V. As the oxide phase containing Bi and V, for example, an oxide phase in which Bi oxide, V oxide, or the like is dispersed, or Bi or V are formed by chemically bonding with a part of the components constituting the soft magnetic alloy particles. A composite oxide phase etc. are mentioned.

The Cr oxide film 4 preferably covers the entire surface of the particles 2, but may be formed intermittently. Although the film thickness of Cr oxide film 4 is not specifically limited, Preferably it is 0.05-0.2 micrometer, More preferably, it is 0.1-0.2 micrometer. The film thickness of the Cr oxide film 4 may not be uniform, and its composition may not be homogeneous.

In this embodiment, phosphorus is contained in the Cr oxide film 4. In addition, in this embodiment, phosphorus is contained also in the grain boundary 6. The method of detecting that phosphorus is included in the Cr oxide film 4 and that phosphorus is included in the grain boundary 6 is not particularly limited, and can be determined, for example, by analyzing a mapping image of phosphorus (P).

In addition, the distinction of the alloy particle 2 and the grain boundary 6 can be performed by observing a magnetic core using a scanning transmission electron microscope (STEM). Specifically, the cross section of the magnetic core is imaged by STEM to obtain a bright field (BF) image. In this bright field image, a region existing between the soft magnetic alloy particles and the soft magnetic alloy particles and having a contrast different from the soft magnetic alloy particles is used as the grain boundary. The determination of whether or not it has a different contrast can be made by the naked eye or by software or the like which performs image processing.

In addition, whether or not the Cr oxide film 4 is present on the surface of the alloy particles 2 can be detected by EDS or EPMA. In addition, the film formed on the surface of the alloy particle 2 as the Cr oxide film 4 can be detected by mapping whether Cr and O are overlapped by mapping Cr and O, respectively, by mapping of EDS or EPMA.

For example, a point where P exists can be observed by determining an observation point from an arbitrary cross section of the magnetic core and performing an EDS analysis or an EPMA analysis. Specifically, a mapping image can be obtained using the qualitative analysis function of this analysis. In a mapping image, the point where there are many elements to observe can be discriminated by color. Visual or analysis software can determine whether P is present in the Cr oxide film 4 or in the grain boundary 6.

Moreover, according to this analysis, concentration distribution of various components in the inside of the alloy particle 2 or its surface can also be confirmed. In addition, according to the STEM analysis, it is possible to specify whether the Cr oxide film 4 formed on the surface of the alloy particles 2 is amorphous or crystalline. In this embodiment, the Cr oxide film 4 may be amorphous or crystalline.

On the other hand, in the green compacted magnetic body according to the present embodiment, elements other than P (Fe, Si, Cr, O, etc.) also exist on the surface and grain boundaries of the soft magnetic alloy particles by the same method as in the case of P. You can determine whether or not you are doing.

In the green compacted magnetic body according to the present embodiment, the content of phosphorus (P) is 40 to 100 ppm with respect to 100 mass% of the green compacted magnetic body, more preferably 60 to 100 ppm. By satisfying the above ranges, the insulation is particularly improved without deteriorating the magnetic properties (particularly the initial permeability μi) in the magnetic core according to the present embodiment. The content of phosphorus (P) in the green compacted magnetic body can be measured by ICP.

According to the green compacted magnetic body according to the present embodiment, since the Cr oxide film 4 containing phosphorus is formed on the surface of the alloy particles 2, and P is included in the grain boundary 6, insulation is particularly improved. do. Moreover, according to the green compacted magnetic body which concerns on this embodiment, there is little deterioration of magnetic characteristics, such as (micro).

In addition, the compaction forming magnetic body according to the present embodiment can be produced by simply including a predetermined amount of phosphorus in the soft magnetic alloy powder as a raw material and appropriately selecting heat treatment conditions as described later. Therefore, manufacture is easy and quality can be stabilized.

The green compacted magnetic body according to the present embodiment may include components such as carbon (C) and zinc (Zn) in addition to the components of the soft magnetic alloy particles.

In addition, it is thought that C originates in the organic compound component used at the manufacturing process of a green compacted magnetic body. In addition, it is thought that Zn originates in the zinc stearate added to a metal mold | die in order to reduce the punching pressure of an apparatus, when a powder compaction magnetic body is obtained by compaction molding.

Content of carbon (C) in the green compacted magnetic body which concerns on this embodiment becomes like this. Preferably it is less than 0.25 mass%, More preferably, it is 0.10-0.20 mass%.

Content of zinc (Zn) in the green compacted magnetic body which concerns on this embodiment becomes like this. Preferably it is 0.004-0.2 mass%, More preferably, it is 0.01-0.2 mass%.

On the other hand, the green compacted magnetic body according to the present embodiment may contain inevitable impurities in addition to the above components.

In another embodiment, Si may further exist at the grain boundaries of the green compacted magnetic body. As a result, the strength can be further improved while maintaining high magnetic properties. In particular, even when molded at a relatively low molding pressure, since sufficient strength can be obtained as a magnetic core, the burden on the mold is also reduced and productivity is improved.

In the green compacted magnetic body according to the present embodiment, Si may exist as a phase containing Si at grain boundaries 6 formed between two particles or grain boundaries (such as triple points) existing between three or more particles. .

As such, the Si-containing phase is present at the grain boundaries, and even when the magnetic core according to the present embodiment is molded at a relatively low molding pressure, sufficient strength can be obtained as the magnetic core. In addition, Si-containing phases serve as an insulator by being present at grain boundaries.

The phase containing Si according to the present embodiment is preferably a Si oxide phase or a Si composite oxide phase. Although it does not specifically limit as a Si oxide phase and a Si composite oxide phase, For example, an amorphous phase containing Si, amorphous silicon, silica, a Si-Cr composite oxide, etc. are mentioned.

In addition, in the green compacted magnetic body according to the present embodiment, the Si-containing phase may also exist on the surface of the soft magnetic alloy particles 2 (interface with the grain boundary 6). For example, the Cr oxide film 4 may be composed of a Si—Cr composite oxide phase. The phase containing Si which concerns on this embodiment, Preferably, it is comprised from amorphous. On the other hand, some may be composed of crystalline.

Next, an example of the manufacturing method of the magnetic core which concerns on this embodiment is demonstrated.

The magnetic core made of the green compacted magnetic body of the present embodiment can be produced by heat-treating a molded body containing a soft magnetic alloy powder and a binder (binder resin). Hereinafter, a preferable manufacturing method is explained in full detail.

The method for producing a compacted compacted magnetic body according to the present embodiment preferably includes a process of mixing a soft magnetic alloy powder and a binder to obtain a mixture,

Drying the mixture to obtain a dried body in a lump state, and then pulverizing the dried body to form granulated powder;

Forming a mixture by molding the mixture or granulated powder into a shape of a compacted compacted magnetic body to be produced;

It has a process of obtaining a powdered magnetic core by heating the obtained molded object.

The shape of the soft magnetic alloy powder is not particularly limited, but is preferably spherical or ellipsoidal in view of maintaining inductance up to a high magnetic field region. Among these, an ellipsoid shape is preferable from the viewpoint of increasing the strength of the green powder core. In addition, the average particle diameter of the soft magnetic alloy powder is preferably 10 to 80 µm, more preferably 30 to 60 µm.

The soft magnetic alloy powder can be obtained by the same method as the preparation method of known soft magnetic alloy powder. At this time, it can prepare using the gas atomization method, the water atomization method, the rotating disk method, etc. Among these, the water atomization method is preferable in order to easily produce the soft magnetic alloy powder having the desired magnetic properties.

Although the method of including phosphorus in the soft magnetic alloy powder is not particularly limited, for example, several methods shown below can be considered.

In the production of the soft magnetic alloy powder, when melting and mixing the raw materials, phosphorus can be included in the soft magnetic alloy powder by mixing phosphorus alone in addition to the phosphorus contained in the raw material of iron alone. In addition, the addition amount of phosphorus (P) is adjusted so that it may become 40-100 ppm after the heat processing of a molded object. It is thought that content of phosphorus (P) does not change before and after heat processing.

When the soft magnetic alloy powder and the binder are mixed to obtain a mixture, the low melting point oxide may be included. The low melting oxide may comprise at least one of Bi and V. As a result, at least one of Bi and V can be efficiently formed at the grain boundary. As such a low melting point oxide, bismuth oxide, vanadium oxide, etc. are mentioned, for example.

The amount of such low melting oxide added is preferably 0.1 to 5.0 parts by mass in terms of Bi ₂ O ₃ or V ₂ O ₅ , based on 100 parts by weight of the soft magnetic alloy powder. By satisfy | filling the said range, Bi and V can be formed efficiently in the grain boundary of a soft magnetic composition, and the intensity | strength of a magnetic core can be improved.

More preferably, the low melting oxide contains at least Bi. The addition amount of the low melting point oxide containing such bismuth (Bi) is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 1.0% by mass in terms of Bi ₂ O ₃ with respect to 100% by mass of the soft magnetic alloy. By satisfy | filling the said range, magnetic property (especially initial permeability (micro)) can be kept high, improving strength.

As the binder, known resins can be used, and various organic polymer resins, silicone resins, phenol resins, epoxy resins, water glass, and the like can be given.

Especially, in this embodiment, what contains a silicone resin preferably is used as a bonding material. By using silicon as the binder, a phase containing Si is effectively formed at the grain boundaries of the soft magnetic composition. The magnetic core formed of such a compacted magnetic body exhibits sufficient strength even when molded at a relatively low molding pressure.

The amount of the binder added depends on the characteristics of the magnetic core required, but preferably 1 to 10 parts by weight can be added to 100 parts by weight of the soft magnetic alloy powder, and more preferably 100 parts by weight of the soft magnetic alloy powder. 2 to 5 parts by weight.

Moreover, an organic solvent can be added to the said mixture or granulated powder as needed in the range which does not prevent the effect of this invention.

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.

Moreover, various additives, lubricants, plasticizers, thixotropic agents, etc. can be added to the said mixture or granulated powder as needed in the range which does not prevent the effect of this invention.

Examples of the lubricant include aluminum stearate, barium stearate, magnesium stearate, calcium stearate, zinc stearate, strontium stearate, and the like. These can be used individually by 1 type or in combination of 2 or more type. Among them, it is preferable to use zinc stearate as a lubricant from the viewpoint of the so-called spring back being small.

When using a lubricant, the addition amount becomes like this. Preferably it is 0.1-0.9 weight part with respect to 100 weight part of soft magnetic alloy powder, More preferably, it is 0.3-0.7 weight part with respect to 100 weight part of soft magnetic alloy powder. When there are too few lubricants, demolding after shaping becomes difficult and there exists a tendency for shaping | molding cracks to occur easily. On the other hand, when there are too many lubricants, a fall of the molding density will result and permeability will reduce.

In particular, when zinc stearate is used as a lubricant, it is preferable to adjust the amount added so that the content of zinc (Zn) in the obtained green compacted magnetic body is within the range of 0.004 to 0.2% by mass.

Although the method of obtaining a mixture is not specifically limited, It can obtain by mixing a soft magnetic alloy powder, a binder, and an organic solvent by a conventionally well-known method. In addition, various additives can be added as needed.

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

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, but after drying the mixture according to a conventionally known method, it can be obtained by pulverizing the dry mixture.

The temperature and time of the drying treatment are preferably 5 to 60 minutes at room temperature to about 200 ° C.

If necessary, a lubricant may be added to the granulated powder. After adding a lubricant to granulated powder, it is preferable to mix for 5 to 60 minutes.

The method for obtaining the molded article is not particularly limited, but the mixture or granulated powder is filled into the cavity using a molding die having a cavity having a desired shape according to a conventionally known method, and the molded article is formed at a predetermined molding temperature and a predetermined molding pressure. Preference is given to compression molding the mixture.

The molding conditions in compression molding are not particularly limited and can be appropriately determined according to the shape and dimensions of the soft magnetic alloy powder, the shape, the size and the density of the powder magnetic 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.

On the other hand, when the molding pressure is too low, it becomes difficult to attain high density and high permeability by molding and tends to be difficult to obtain sufficient mechanical strength. On the other hand, if the molding pressure at the time of molding is too high, the pressure application effect tends to be saturated, the manufacturing cost increases, and the productivity and economy tend to be impaired. There is a tendency.

Although molding temperature is not specifically limited, Usually, room temperature to about 200 degreeC is preferable. On the other hand, although the density of the molded article tends to increase as the molding temperature is increased at the time of molding, if it is too high, the oxidation of the soft magnetic alloy particles is promoted, and the performance of the obtained green powder core tends to be deteriorated, and the production cost increases. Productivity and economics may be lowered.

Although the method of heat-processing the molded object obtained after shaping | molding is not specifically limited, It is preferable to carry out by heat-processing the molded object shape | molded to arbitrary shape by shaping | molding at predetermined temperature using an annealing furnace.

Although the processing temperature at the time of heat processing is not specifically limited, About 700-1000 degreeC is preferable, More preferably, it is 800-1000 degreeC, Especially preferably, it is 800-900 degreeC. If the processing temperature at the time of heat treatment is too low, it becomes difficult to form the Cr oxide film 4 containing P, and it becomes difficult to form the grain boundary 6 containing P, and it becomes difficult to aim at insulation improvement. . Moreover, when heat processing temperature is too high, there exists a tendency for the alloy particle 2 to oxidize and insulation falls.

It is preferable to perform a heat processing process in oxygen-containing atmosphere. Here, the oxygen-containing atmosphere is not particularly limited, but may be an atmospheric atmosphere (usually containing 20.95% oxygen) or a mixed atmosphere with an inert gas such as argon or nitrogen. Preferably it is in an atmospheric atmosphere. By heat-processing in an oxygen containing atmosphere, it becomes easy to form the Cr oxide film 4 containing P, and it is easy to form the grain boundary 6 containing P.

Moreover, it is preferable that the compacted magnetic core obtained in this way is 5.50g / cm <3> or more. The compacted magnetic core, which has a high molding density of 5.50 g / cm 3 or more, also tends to be excellent in various performances such as high permeability, high strength, high core resistance, and low core loss.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, It can change into various forms within the range of this invention.

For example, in the above-described embodiment, magnetic cores (pressing magnetic cores) are produced by press-molding a mixture or granulated powder, but magnetic cores can also be produced by molding and laminating the mixture into a sheet shape. In addition to the dry molding, a molded product can be obtained by wet molding, extrusion molding, or the like.

In addition, although the magnetic core which concerns on this embodiment is used as a coil-type electronic component in embodiment mentioned above, it does not restrict | limit especially, The magnetic core of various electronic components, such as a motor, a switching power supply, a DC-DC converter, a transformer, a choke coil, etc. It can also use suitably as. Among them, it is more preferable to use it as a portable DC-DC converter.

In addition, in the above-described embodiment, the magnetic core is constituted by the green compacted magnetic body according to the present invention. In addition to the magnetic core, the body body or other molded body of the electronic component can be constituted by the compacted magnetic body according to the present invention.

<Example>

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]

First, an ingot, chunk (lump), or shot (particle) of Fe alone, Cr alone, and Si alone was prepared. Next, these were mixed so as to have a composition of 89.5% by mass of Fe, 6.5% by mass of Si, and 4.0% by mass of Cr, and placed in a crucible arranged in a water atomizing device. Subsequently, the crucible was heated to 1600 degreeC or more by high frequency induction using the work coil provided outside the crucible in inert atmosphere, and the ingot, the chunk, or the short in a crucible were melted and mixed, and the melt was obtained.

Subsequently, the melt in the crucible is ejected from the nozzle provided in the crucible, and at the same time, the high-pressure (50 MPa) water stream is collided with the ejected melt and quenched, thereby producing a soft magnetic alloy powder composed of Fe-Si-Cr-based particles (average particle diameter; 50 µm). ) Was produced.

As a result of composition analysis of the obtained soft magnetic alloy powder by fluorescence X-ray spectroscopy, it was confirmed that it coincided with the addition composition. In addition, adjustment of the content of phosphorus contained in the soft magnetic alloy powder was performed by adjusting the amount of phosphorus contained in the raw material of iron alone, when melting and mixing a raw material at the time of preparation of a soft magnetic alloy powder.

[Production of powdered magnetic core]

To 100 parts by weight of the obtained soft magnetic alloy powder, 6 parts by weight of a silicone resin (manufactured by Toray Dow Corning Silicon Co., Ltd .: SR2414LV) was added, and these were mixed for 30 minutes at room temperature with a pressure kneader. The mixture was then dried for 20 minutes at 150 ° C. in air. To 100 parts by weight of the soft magnetic alloy powder, 0.5 parts by weight of zinc stearate (nitto chemical: zinc stearate) was added to the magnetic powder after drying, and mixed for 10 minutes by a V mixer.

Subsequently, the obtained mixture was molded into a 5 mm x 5 mm x 10 mm square sample to form a molded body. On the other hand, the molding pressure was set to 600 MPa. By heat-processing the molded object after pressurization at 800 degreeC for 60 minute (s) in air | atmosphere, the magnetic core which consists of a powder compacted magnetic body (pressed powder magnetic core) was obtained.

[Various evaluation]

<Observation of grain boundary>

 First, the green magnetic core was cut. This cut surface was observed with the scanning transmission electron microscope (STEM), and the soft magnetic alloy particle 2 and the grain boundary 6 were discriminated. In addition, about Cr, O, P, and Si, EDS analysis confirmed the presence of the surface of the particle | grains 2 and the grain boundary 6, respectively.

<Initial permeability (μi)>

The green magnetic core sample was wound 10 turns of copper wire to measure an initial permeability (μi) using an LCR meter (Hewlett Packard 4284A). As measurement conditions, the measurement frequency was 1 MHz, the measurement temperature was 23 ° C., and the measurement level was 0.4 A / m.

<Insulation Resistance (IR)>

Insulation resistance IR was calculated | required on 50 V conditions using High-Resistance-Meter (Agilent # 4339B) for the green magnetic core sample.

<Evaluation>

The result of having investigated the change of initial permeability and insulation resistance by changing content of phosphorus (P) contained in a powder magnetic core from 0.003 mass% (30 ppm) to 0.011 mass% (110 ppm) is shown in FIG.

As shown in FIG. 2, when the content of phosphorus (P) was set from 0.004% by mass (40 ppm) to 0.010% by mass (100 ppm), the IR was significantly improved, and it was confirmed that the deterioration of μi was small. If the content of phosphorus (P) is less than 0.004% by mass (40 ppm), the insulation resistance is too low, which is not preferable. If the content of phosphorus (P) is more than 0.010% by mass (100 ppm), the reduction ratio of μi is preferably 20% or more. Not.

Moreover, the green magnetic core sample whose content of phosphorus (P) is 0.010 mass% (100 ppm) is cut out from 0.004 mass% (40 ppm), and this cut surface is observed with a scanning transmission electron microscope (STEM), and Cr, O, As a result of performing EDS analysis about P and Si, as shown in FIG. 1 which is a STEM image, the Cr oxide film 4 containing phosphorus is formed in the surface of the alloy particle 2, and phosphorus also exists in the grain boundary 6; It was confirmed that it was included.

(Comparative Example 1)

Except having made heat processing temperature into 500 degreeC, the pressed magnetic core sample was created like Example 1, and the same measurement was performed. No Cr oxide film containing phosphorus was observed on the surface of the alloy particles, and no phosphorus was observed at grain boundaries. Moreover, even if content of phosphorus was 40-100 ppm, as shown in FIG. 2, the increase of insulation resistance was not observed. Since the heat treatment temperature is low, it is considered that Cr oxide film containing phosphorus is not observed on the surface of the alloy particles, phosphorus is not observed even at grain boundaries, and no increase in insulation resistance is observed.

(Example 2)

Except having used non-silicone-type resin (made by Nagase ChemteX Corp .: DENATITE XNR 4338) as binder resin, the same powdered magnetic core sample as Example 1 was created, and the same measurement was performed. The same result as in Example 1 was obtained.

2… Soft magnetic alloy particles 4... Contains phosphorus
6... Cr oxide film

Claims (5)

As a green compacted magnetic body comprising alloy particles composed of a Fe-Si-Cr based soft magnetic alloy,
Phosphorus is contained 40 to 100ppm,
Cr oxide film containing phosphorus is formed on the surface of the alloy particles,
A compacted compacted magnetic body, wherein phosphorus and Cr contained in the Cr oxide film are derived from the alloy particles. The method of claim 1,
A powder compacted magnetic body, wherein phosphorus is included in grain boundaries between the alloy particles. The method of claim 2,
The green compacted magnetic body, wherein the phosphorus contained in the grain boundary is derived from the alloy particles. The magnetic core comprised from the green compacted magnetic body of any one of Claims 1-3. It has a magnetic core of Claim 4, The coil type electronic component characterized by the above-mentioned.

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