JP2014175580A - Dust core, coil component using the same and method of producing dust core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration suitable for reducing core loss, in a dust core composed of soft magnetic material powder and a coil component using the same.SOLUTION: In a dust core composed of soft magnetic material powder 1, the soft magnetic material powder 1 is Fe-based amorphous alloy atomization powder, and Cu2 is dispersed between the soft magnetic material powder. A method of producing a dust core composed of soft magnetic material powder includes a first step for mixing the soft magnetic material powder, i.e., Fe-based amorphous alloy atomization powder, and Cu powder, and a second step for pressure molding a mixed powder obtained in the first step. A dust core in which Cu is dispersed between the Fe-based amorphous alloy atomization powder is obtained.

Description

  The present invention relates to a dust core used in, for example, home appliances such as televisions and air conditioners, solar power generation, power supply circuits of motor-driven vehicles, and the like, a coil component using the same, and a method of manufacturing a dust core.

  The first stage part of the power supply circuit of the home appliance is composed of an AC / DC converter circuit that converts an AC (alternating current) voltage into a DC (direct current) voltage. In this AC / DC converter circuit, a PFC circuit is used to control the waveform of the AC input current to be shaped into the same phase and waveform as the AC input voltage, and to reduce reactive power and harmonic noise. In order to reduce the size and height of a choke used in such a PFC circuit, a magnetic core used for the choke is required to have a high saturation magnetic flux density, a low core loss, and excellent direct current superposition characteristics.

  In recent years, a reactor that can withstand a large current is used in a power supply device mounted on a motor-driven vehicle such as a hybrid vehicle or an electric vehicle or a solar power generation device that has begun to spread rapidly. The reactor core is similarly required to have a high saturation magnetic flux density and a low loss.

  In order to meet the above requirements, a dust core excellent in the balance between high saturation magnetic flux density and low loss is employed. The dust core is obtained by molding a soft magnetic material powder such as Fe—Si, and the electrical resistance is increased by the insulation treatment of the powder and eddy current loss is suppressed. Fe-based amorphous alloys are also used as soft magnetic material powder with lower loss. As the powder of the Fe-based amorphous alloy, for example, atomized powder obtained by a water atomization method or the like is commercially available. In Patent Document 1, an amorphous soft magnetic alloy powder is used as a soft magnetic material powder having a low loss, and a glass powder and a binder resin are mixed with the powder to obtain a low loss powder magnetic core. A method is disclosed.

JP 2010-27854 A

  As in Patent Document 1, it is possible to reduce eddy current loss by adding an insulating material such as glass powder. However, as the eddy current loss is reduced, the ratio of the insulating material increases. At the same time, there is a problem that the magnetic properties such as the space factor and the magnetic permeability of the dust core are greatly reduced.

  Therefore, in view of the above problems, the present invention provides a dust core capable of effectively reducing core loss while suppressing a decrease in space factor, a coil component using the same, and a method of manufacturing a dust core The purpose is to provide.

  The dust core of the present invention is a dust core composed of soft magnetic material powder, wherein the soft magnetic material powder is Fe-based amorphous alloy atomized powder, and Cu is interposed between the soft magnetic material powders. It is distributed. By adopting a configuration in which Cu is dispersed between soft magnetic material powders, it is possible to reduce core loss while suppressing a decrease in space factor.

  Moreover, in the said powder magnetic core, it is preferable that content of the said Cu is 0.01-3 mass% with respect to the total mass of the said soft-magnetic material powder and the said Cu.

  The coil component of the present invention includes any one of the powder magnetic cores and a coil wound around the powder magnetic core.

  The method for producing a dust core according to the present invention is a method for producing a dust core composed of soft magnetic material powder, wherein the soft magnetic material powder is Fe-based amorphous alloy atomized powder, and the Fe-based amorphous A first step of mixing the alloy atomized powder and the Cu powder, and a second step of pressure forming the mixed powder obtained in the first step. A powder magnetic core in which Cu is dispersed is obtained.

  Moreover, in the manufacturing method of the said powder magnetic core, it is preferable that content of the said Cu powder is 0.01-3 mass% with respect to the total mass of the said soft-magnetic material powder and the said Cu powder.

  Furthermore, in the method of manufacturing a dust core, in the first step, it is preferable that the soft magnetic material powder and the Cu powder are mixed first, and then a binder is added and further mixed.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the powder magnetic core which can reduce core loss effectively while suppressing the fall of a space factor, the coil components using this, and a powder magnetic core can be provided.

It is a mimetic diagram of a dust core section for showing a concept of a dust core concerning the present invention.

  Hereinafter, embodiments of the powder magnetic core and the coil component according to the present invention will be specifically described, but the present invention is not limited thereto.

  FIG. 1 is a schematic view showing a cross section of a dust core according to the present invention. The dust core 100 is configured using soft magnetic material powder. As the soft magnetic material powder 1, Fe-based amorphous alloy atomized powder is used. Fe-based amorphous alloys have a lower loss than crystalline soft magnetic material powders such as Fe-Si. In addition, atomized powder obtained by an atomizing method such as a water atomizing method or a gas atomizing method typically has a granular shape and is excellent in fluidity as compared with a flat powder or a needle-shaped powder.

  In the dust core 100 in FIG. 1, Cu (metallic copper) 2 is dispersed between granular soft magnetic material powders 1. Such a configuration can be obtained by compacting a mixed powder of soft magnetic material powder and Cu powder. The mixed Cu powder is interposed between the soft magnetic material powders 1. In the following description, Cu interposed between the soft magnetic material powders 1 in the dust core may also be referred to as Cu powder for convenience.

  Since Cu is usually softer than soft magnetic material powder, it tends to be plastically deformed during consolidation and contributes to improving density in this respect. Moreover, the effect that the stress to soft magnetic material powder is relieved by such plastic deformation can also be expected. Moreover, in order to disperse Cu between soft magnetic material powder, the method of adding Cu powder during a manufacturing process is employable. At this time, the Cu powder is preferably spherical. By containing such Cu powder, the fluidity of the powder is improved during pressure molding, and the density and space factor of the powder magnetic core are also improved.

  Here, an important feature of the present invention will be described. The present inventor has found a unique and remarkable effect by addition of Cu powder, which is different from the addition of an insulating material such as glass powder as disclosed in Patent Document 1, and has reached the present invention. That is, by adding Cu powder, the dispersion of Cu between soft magnetic material powders has a particularly remarkable effect not only for increasing the density as described above but also for reducing the loss.

  By using Cu powder smaller than the soft magnetic material powder, Cu 2 can be dispersed between the soft magnetic material powders 1. With this configuration, the core loss is reduced as compared with the case where Cu powder is not included, that is, Cu is not dispersed. Since Cu exhibits a remarkable core loss reduction effect even in a very small amount, the amount of Cu used can be suppressed. Conversely, if the amount used is increased, the effect of significant core loss reduction can be obtained. Therefore, it can be said that the structure containing Cu powder and dispersing Cu between the soft magnetic material powders is suitable for reducing the core loss.

The remarkable effect by the Cu dispersion cannot be obtained for crystalline low-loss materials such as Fe-6.5Si soft magnetic materials and Fe-3.5Si soft magnetic materials. The magnetostriction constant of Fe-6.5Si soft magnetic material or the like is 1 × 10 ⁻⁵ or less, whereas the magnetostriction constant of Fe-based amorphous alloy exceeds 1 × 10 ⁻⁵ and is extremely large. A typical magnetostriction constant of the Fe-based amorphous alloy is 2.7 × 10 ⁻⁵ . By applying the structure of Cu dispersion to the atomized powder of the Fe-based amorphous alloy, a unique and remarkable core loss reduction effect can be obtained. It is considered that Cu dispersion contributes to core loss reduction through stress relaxation to the soft magnetic material powder during molding.

  In the present invention, Cu is dispersed between soft magnetic material powders, and it is not always necessary that Cu is present in the gaps between all soft magnetic material powders, and at least a part of the soft magnetic material powders. The purpose is that Cu may be present in the gap between the two. Further, since the core loss is reduced as the amount of dispersed Cu is increased, the content of Cu is not limited from the viewpoint of reducing the core loss. However, since Cu itself is a non-magnetic material, considering the function as a magnetic core, the content of Cu (Cu powder) is, for example, 15 with respect to the total mass of the soft magnetic material powder and Cu (Cu powder). A mass% or less is a practical range.

  Cu exhibits a sufficient loss-reducing effect even with a small amount, while the magnetic permeability decreases when the Cu content is excessive. The content of Cu (Cu powder) is more preferably 0.01 to 3% by mass with respect to the total mass of the soft magnetic material powder and Cu (Cu powder). According to such a configuration, it is possible to suppress the reduction rate of the magnetic permeability within 2% with respect to the case of not containing Cu while enhancing the effect of reducing the loss.

  In the present invention, the hysteresis loss can be mainly reduced among the core loss by dispersing Cu in the soft magnetic material powder. The conventional method of adding an insulating material such as an oxide is aimed at reducing eddy current loss by improving insulation resistance. Therefore, in order to reduce eddy current loss, it is necessary to increase the amount of addition, and the above method involves sacrifice of other characteristics such as space factor and magnetic permeability. On the other hand, in this invention, Cu can be disperse | distributed and core loss can be reduced, suppressing the fall of a space factor etc. by reducing the ratio of hysteresis loss.

For example, it is possible to reduce the overall core loss by setting the hysteresis loss under the measurement conditions of a frequency of 20 kHz and an applied magnetic flux density of 150 mT to 80 kW / m ³ or less. By reducing the core loss, it is possible to increase the efficiency and miniaturization of coil parts and devices using the core loss.

  The form of dispersed Cu is not particularly limited. Further, the form of Cu powder that can be used as a raw material for Cu dispersed in the dust core is not limited thereto. However, from the viewpoint of improving fluidity during pressure molding, the Cu powder is more preferably granular, particularly spherical. Such Cu powder is obtained by, for example, an atomizing method, but is not limited thereto. Moreover, although it is possible for Cu powder to contain elements other than Cu, it is preferable to comprise Cu other than unavoidable impurities.

  The particle size of Cu powder should just be a magnitude | size which is smaller than soft-magnetic material powder, and can be disperse | distributed among soft-magnetic material powder. The granular powder softer than the soft magnetic alloy, such as Cu powder, improves the fluidity of the soft magnetic material powder and plastically deforms during consolidation, thereby reducing the gap between the soft magnetic material powders. The average particle diameter (median diameter D50) of the Cu powder used for the dust core is more preferably 50% or less of the average particle diameter (median diameter D50) of the soft magnetic material powder. The finer the Cu powder, the easier it is to disperse between the soft magnetic material powders, and the range of the average particle diameter of the applicable soft magnetic material powders is widened. Therefore, the average particle diameter of the Cu powder is preferably 20 μm or less, preferably 10 μm or less. More preferred. On the other hand, if the particle size becomes too small, the cohesive force between the Cu powders becomes large and dispersion becomes difficult, so the average particle size of the Cu powder is more preferably 2 μm or more.

  The particle diameter of Cu powder used as a raw material for the dust core can be evaluated as a median diameter D50 (particle diameter corresponding to 50% by volume) measured by a laser diffraction / scattering method. The diameter of the Cu particles dispersed and softly deformed between the soft magnetic material powders is slightly larger than the particle diameter of the Cu powders in the above-mentioned powder state. The numerical value of the particle size of the Cu powder observed and measured by (hereinafter referred to as SEM) is approximately the same as the median diameter D50 of the Cu powder as a raw material. Therefore, also in the SEM observation of the dust core, it can be confirmed that the particle diameter of Cu is smaller than that of the soft magnetic material powder and Cu is dispersed between the soft magnetic material powders.

  The atomized powder used as the soft magnetic material powder is obtained by quenching a melt of a soft magnetic material alloy using a fluid, such as a water atomizing method or a gas atomizing method. The specific alloy composition is not particularly limited, and can be selected according to required characteristics. For example, as an Fe-based amorphous alloy atomized powder having a high saturation magnetic flux density Bs of 1.4 T or higher, an amorphous alloy atomized powder such as Fe—Si—B type can be used.

On the other hand, instead of Fe-based amorphous alloy atomized powder, Fe-based nanocrystals having a large magnetostriction constant exceeding 1 × 10 ⁻⁵ such as Fe—Cu—Si—B and Fe—Ni—Cu—Si—B Alloy atomized powder can also be used. As described above, when the Fe-based nanocrystalline alloy atomized powder is used as the magnetic material, the soft magnetic material powder only needs to have a nanocrystalline structure in the finally obtained dust core. Therefore, at the time of forming, the soft magnetic material powder may be an Fe-based nanocrystalline alloy or an Fe-based amorphous alloy that can develop an Fe-based nanocrystalline structure. An alloy capable of developing an Fe-based nanocrystalline structure means that even if it is in the state of an amorphous alloy at the time of molding or the like, the soft magnetic material powder has an Fe-based nanocrystalline structure in the final dust core after crystallization treatment. Says what you are doing. For example, this is the case when the crystallization heat treatment is performed after molding.

  The particle diameter of the soft magnetic material powder used for the dust core can be selected according to the required characteristics. For example, soft magnetic material powder having an average particle size of 5 to 100 μm can be used. From the viewpoint of moldability and cost, the average particle diameter of the soft magnetic material powder is preferably 40 μm or more. On the other hand, when importance is attached to the frequency characteristics, the average particle diameter is preferably 20 μm or less. The average particle diameter of the soft magnetic material powder used for the dust core can also be evaluated as a median diameter D50 (particle diameter corresponding to 50% by volume) measured by a laser diffraction / scattering method.

  Moreover, in this invention, in addition to the above-mentioned atomized powder, it is also possible to contain other magnetic powder. However, in order to maximize the effect of the Cu powder, it is more preferable that the magnetic powder is composed only of the atomized powder. Moreover, in this invention, it is also possible to contain nonmagnetic metal powders other than Cu powder. However, in order to maximize the effect of Cu powder, it is more preferable that the nonmagnetic metal powder is only Cu powder.

  In the dust core, eddy current loss can be suppressed and low core loss can be realized by applying means for insulating between soft magnetic material powders. Therefore, it is preferable to provide a thin insulating film on the surface of the soft magnetic material powder. It is also possible to oxidize the soft magnetic material powder itself to form an oxide film on the surface. However, since it is not always easy to form a uniform and reliable oxide film while suppressing damage to the soft magnetic material powder by such a method, an oxidation different from the oxide of the alloy component of the soft magnetic material powder. It is preferable to provide a physical coating.

  In this regard, a configuration in which a silicon oxide film is provided on the surface of the soft magnetic material powder is preferable. Silicon oxide is excellent in insulating properties, and it is easy to form a uniform film by a method described later. In order to ensure insulation, the thickness of the silicon oxide film is preferably 50 nm or more. On the other hand, when the silicon oxide film becomes too thick, the space factor of the powder magnetic core decreases, the distance between the soft magnetic material powders increases, and the magnetic permeability decreases. Therefore, the film is preferably 500 nm or less.

  Next, the manufacturing process of the powder magnetic core in which Cu is dispersed will be described. The manufacturing method of the present invention is a manufacturing method of a powder magnetic core configured using soft magnetic material powder, wherein the soft magnetic material powder is Fe-based amorphous alloy atomized powder, and the Fe-based amorphous alloy atomized powder and It has the 1st process of mixing Cu powder, and the 2nd process of pressure-molding the mixed powder obtained at the 1st process. Through the first step and the second step, a dust core in which Cu is dispersed between the Fe-based amorphous alloy atomized powders is obtained. About content of Cu (Cu powder), it is more preferable that it is 0.01-3 mass% with respect to the total mass of soft-magnetic material powder and Cu (Cu powder) as mentioned above. The preferred range of the configuration other than the content of Cu (Cu powder) is also as described above.

  What is necessary is just to apply suitably the structure which concerns on the manufacturing method of the powder magnetic core conventionally known to parts other than a 1st process and a 2nd process as needed.

  First, an example of a method for producing a soft magnetic material powder used in the first step will be described. The atomized powder used as the soft magnetic material powder is obtained by rapidly cooling the molten metal of the soft magnetic material alloy using a fluid as described above. The obtained atomized powder may be used as it is or may be further classified in order to control the particle size distribution. The classification method is not particularly limited, but a method using a sieve is simple and preferable.

  As described above, an insulating film can be formed on the soft magnetic material powder in order to reduce the loss. The formation method will be described below. For example, by heat-treating Fe-based amorphous alloy atomized powder at 100 ° C. or higher in a humid atmosphere, Fe on the surface is oxidized or hydroxylated to form an insulating film of iron oxide or iron hydroxide.

  In addition, a silicon oxide film can be formed on the surface of the soft magnetic material powder by impregnating the soft magnetic material powder in a mixed solution of TEOS (tetraethoxysilane), ethanol, and ammonia water, stirring, and drying. . According to this method, it is not necessary to oxidize the surface of the soft magnetic material powder itself, and silicon and oxygen are combined, and a silicon oxide film is formed in a planar and network form on the surface of the soft magnetic alloy powder. A strong insulating film can be formed on the surface of the soft magnetic material powder with a uniform thickness.

  Next, the first step of mixing soft magnetic material powder and Cu powder will be described. The mixing method of the soft magnetic material powder and the Cu powder is not particularly limited, but for example, a dry stirring mixer can be used. Furthermore, the organic binder etc. which are mentioned later can be mixed in a 1st process. Soft magnetic material powder, Cu powder, organic binder and the like can be mixed at the same time. However, from the viewpoint of mixing soft magnetic material powder and Cu powder uniformly and efficiently, in the first step, soft magnetic material powder and Cu powder are mixed first, and then a binder is added. Further mixing is more preferable. By doing so, uniform mixing can be performed in a shorter time, and the mixing time can be shortened.

  An organic binder can be used to bind the powders and maintain the strength of the compact. On the other hand, application of post-molding heat treatment, which will be described later, is effective for removing the processing distortion of molding. When the heat treatment is applied, the organic binder is generally lost by thermal decomposition. Therefore, in the case of only the organic binder, the binding force between the soft magnetic material powder and the Cu powder after heat treatment is lost, and the strength of the compact may not be maintained. Therefore, it is effective to add a high-temperature binder together with the organic binder in order to bind the powders even after the heat treatment. The binder for high temperature represented by the inorganic binder is preferably one that starts to exhibit fluidity in a temperature range where the organic binder is thermally decomposed, spreads on the powder surface, and binds the powders together. By applying a high-temperature binder, the binding force can be maintained even after cooling to room temperature.

  Organic binders can be easily pyrolyzed by heat treatment after molding while maintaining the binding force between the powders so that chipping and cracks do not occur in the molded body during handling before the molding process and heat treatment. preferable. As the binder for which thermal decomposition is almost completed by heat treatment after molding, an acrylic resin or polyvinyl alcohol is preferable.

  As the binder for high temperature, a low-melting glass capable of obtaining fluidity at a relatively low temperature and a silicone resin excellent in heat resistance and insulation are preferable. As the silicone resin, methyl silicone resin and phenylmethyl silicone resin are more preferable. The amount to be added is determined by the fluidity of the binder for high temperature, the wettability with the powder surface and the binding force, the surface area of the metal powder, the mechanical strength required for the core after heat treatment, and the required core loss Pcv. Increasing the amount of high-temperature binder added increases the mechanical strength of the dust core, but also increases the stress on the soft magnetic material powder. For this reason, the core loss Pcv also increases. Therefore, the low core loss Pcv and the high mechanical strength are in a trade-off relationship. In view of the required core loss Pcv and mechanical strength, the addition amount is optimized.

  Furthermore, in order to reduce the friction between the powder and the mold at the time of pressure molding, stearinate such as stearic acid or zinc stearate, soft magnetic material powder and Cu powder, organic binder, high temperature binder It is preferable to add 0.5 to 2.0 mass% with respect to the mass. In a state where the organic binder is mixed, the mixed powder is an agglomerated powder having a wide particle size distribution due to the binding action of the organic binder. By passing through a sieve using a vibrating sieve or the like, a granulated powder having a uniform particle diameter can be obtained.

The mixed powder obtained in the first step is granulated as described above and provided for the second step. In the second step, the granulated mixed powder is pressure-molded into a predetermined shape such as a toroidal shape or a rectangular parallelepiped shape using a molding die. For example, molding is performed at a pressure of 1 GPa or more and 3 GPa or less with a holding time of about several seconds. The pressure and holding time are optimized depending on the content of the organic binder and the required strength of the molded body. From the viewpoint of strength and characteristics, the dust core is preferably compacted to 5.3 × 10 ³ kg / m ³ or more practically.

  In order to obtain good magnetic properties, it is preferable to relieve stress strain in the second step of molding. In the case of an Fe-based amorphous alloy atomized powder, heat treatment in a temperature range of 350 ° C. or higher and lower than the crystallization temperature (typically 420 ° C. or lower) has a large effect of stress strain relaxation, and a low core loss Pcv can be obtained. The crystallization temperature can be determined by measuring the exothermic behavior with a differential scanning calorimeter (DSC). When the temperature is lower than 350 ° C., the stress relaxation is insufficient, and when the temperature exceeds the crystallization temperature, coarse crystal grains are precipitated in a part of the soft magnetic material powder, so that the core loss Pcv is remarkably increased. Further, in order to obtain a stable and low core loss Pcv, the heat treatment temperature is more preferably 380 ° C. or more and 410 ° C. or less. The holding time is appropriately set according to the size of the dust core, the processing amount, the allowable range of variation in characteristics, and the like, but is preferably 0.5 to 3 hours.

  The coil component of the present invention includes the dust core obtained as described above, and a coil wound around the dust core. The coil may be configured by winding a conductive wire around a powder magnetic core, or may be configured by winding it around a bobbin. The coil component is, for example, a choke, an inductor, a reactor, a transformer, or the like. The coil parts are used in, for example, PFC circuits used in household appliances such as televisions and air conditioners, and power circuits for photovoltaic power generation, hybrid vehicles, and electric vehicles. Low loss and high efficiency in these devices and devices Contributes to

(First step (mixing of soft magnetic material powder and Cu powder))
As raw materials for the powder magnetic core, spherical Fe-Si-B-Cr-based Fe-based amorphous alloy atomized powder (Epson Atmix Co., Ltd. KUAMET 6B2) with an average particle diameter of 50 μm and spherical Cu powder with an average particle diameter of 5 μm (Nippon Atomize Co., Ltd. HXR-Cu M-01) was used. 1.4 parts by weight of phenylmethyl silicone (SILRES H44 manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) as a high-temperature binder with respect to a total of 100 parts by weight of the soft magnetic material powder and the Cu powder weighed to have the ratio shown in Table 1. After adding 2.0 parts by weight of an acrylic resin (Polysol AP-604 manufactured by Showa Polymer Co., Ltd.) as a binder and mixing, the mixture was dried at 120 ° C. for 10 hours to obtain a mixed powder.

(Second step (pressure forming) and heat treatment)
Each mixed powder obtained in the first step was passed through a sieve having an opening of 425 μm to obtain granulated powder. By passing through a sieve having an opening of 425 μm, a granulated powder having a particle size of about 600 μm or less is obtained. After mixing this granulated powder with zinc stearate at a ratio of 0.4 parts by weight with respect to a total of 100 parts by weight of the soft magnetic material powder and the Cu powder, a toroidal shape having an outer diameter of 14 mm, an inner diameter of 8 mm, and a height of 6 mm is obtained. In this way, press molding was performed using a mold at a pressure of 2 GPa and a holding time of 2 seconds. The obtained molded body was subjected to heat treatment in an atmosphere at 450 ° C. for 1 hour in an oven to obtain a dust core (Nos. 1 to 8).

  For comparison, Fe-3.5Si powder having an average particle size of 20 μm is used instead of Fe-based amorphous alloy atomized powder, and Cu powder is not contained (No 9) and 2.0 mass% (No 10). Two types of dust cores were produced. An acrylic resin (Polysol AP-604 manufactured by Showa Polymer Co., Ltd.) was used as the binder, and the amount added was 1.5 parts by weight with respect to 100 parts by weight of the total soft magnetic material powder and Cu powder. The heat treatment was performed in an air atmosphere at 450 ° C. for 1 hour.

  The density of the obtained powder magnetic core is calculated from its size and mass, and the calculated density of the powder magnetic core is divided by the true density calculated from the mass ratio of the soft magnetic material powder and the Cu powder to obtain a space factor. (Relative density) was calculated. In addition, the primary and secondary windings of 29 turns were applied to the dust core, and the core loss Pcv was measured with a BH analyzer SY-8232 manufactured by Iwatatsu Measurement Co., Ltd. under the conditions of a maximum magnetic flux density of 150 mT and a frequency of 20 kHz. did. The initial permeability μi was measured at a frequency of 100 kHz using a 4284A manufactured by Hewlett-Packard Co., Ltd., with the toroidal powder magnetic core wound with 30 turns. The results are shown in Table 1.

For some dust cores, the frequency dependence of the core loss when the frequency f is changed between 10 kHz and 100 kHz is measured separately from the core loss measurement, and the portion a proportional to the frequency f Hysteresis loss and eddy current loss were separated and evaluated, where xf was hysteresis loss Phv and a portion b × f ² proportional to the square f ^{2 of} frequency f was eddy current loss Pev. The results are shown in Table 2.

The sample No. 1 in Table 1 was a dust core of a comparative example not containing Cu powder, and the core loss Pcv was as large as 115 kW / m ³ . The sample of No. 2 is a dust core of the present invention containing 0.01 mass% of Cu (Cu powder), the core loss Pcv is 100 kW / m ³ or less, and the loss is 15% compared to the case where Cu is not added. The above has been reduced. That is, it can be seen that the core loss is greatly reduced by containing Cu powder even in a very small amount.

  Nos. 2 to 8 in Table 1 indicate the core loss Pcv of the dust core when the Cu powder content is increased from 0.01% by mass to 7.0% by mass in the present invention example. The core loss Pcv decreased as the amount of Cu powder increased. From the results in Table 1, it can be seen that the core loss Pcv can be reduced by 40% or more when the Cu powder content is 1.0% by mass or more, and can be reduced by 50% or more when the content is 2.0% by mass or more. In addition, when Cu powder was added, the space factor was equal to or higher than that when Cu powder was not added, and a space factor of 80% or higher was ensured.

  Furthermore, when the content of Cu powder is relatively small, a decrease in initial magnetic permeability with respect to an increase in the content of Cu powder was also suppressed. The results of Table 1 show that the decrease in the permeability with respect to the dust core not containing Cu powder is 25 by setting the content of Cu powder to 5.0 mass% or less, and further to 3.0 mass% or less. It is shown that it can be suppressed to within 2% or within 2%. In particular, it can be seen that when the Cu powder content is 2.0% or less, an initial permeability higher than that of a dust core not containing Cu powder is obtained even though Cu is a non-magnetic material.

By containing Cu as described above, core loss can be reduced while suppressing a decrease in space factor and initial permeability. For example, it is possible to obtain a dust core having an initial permeability μi of 50 or more at a frequency of 100 kHz and a core loss Pcv of 100 kW / m ³ or less at a frequency of 20 kHz and a magnetic flux density of 150 mT. By using such a powder magnetic core, it is possible to increase the efficiency and miniaturization of the coil component and the apparatus using the same. Using a powder magnetic core having an initial permeability μi of 55 or more at a frequency of 100 kHz, a core loss Pcv of 80 kW / m ³ or less at a frequency of 20 kHz and a magnetic flux density of 150 mT, further improving the efficiency and miniaturization of a coil component and a device using the same. It is also possible to

Table 2 shows the results of evaluating the eddy current loss Pev and the hysteresis loss Phv for the Nos. 1-7 dust cores. Since the core loss itself of the No. 8 dust core was very small and the eddy current loss Pev and the hysteresis loss Phv could not be clearly separated, they were excluded from the evaluation. As is clear from Table 2, the eddy current loss Pev was in the range of ^{30 to} 33 kW / m ³ regardless of the Cu powder content, and showed no significant change. That is, it can be seen that the effect of reducing the core loss by containing the Cu powder is mainly brought about by the reduction of the hysteresis loss. The ratio of the hysteresis loss Phv to the sum of the eddy current loss Pev and the hysteresis loss Phv under the measurement conditions of a frequency of 20 kHz and an applied magnetic flux density of 150 mT is 60% or less when the Cu powder content is 1.0 mass% or more. When the content was 3.0% by mass or more, the content decreased to 50% or less, and each contributed to the reduction of the entire core loss.

  On the other hand, Nos. 9 and 10 are dust cores using Fe-3.5Si powder instead of Fe-based amorphous alloy atomized powder. The core loss Pcv of the No. 10 dust core containing 2.0% by mass of Cu powder is increased with respect to the core loss Pcv of the No. 9 dust core containing no Cu powder, and the No. 5 containing the same amount of Cu powder. The core loss reduction effect by Cu content confirmed in the dust core was not obtained. That is, it was confirmed that effects such as core loss reduction by containing Cu powder could not be obtained when applied to magnetic powder made of Fe-3.5Si powder.

1: Soft magnetic material powder 2: Cu (Cu powder)

Claims (6)

A dust core made of soft magnetic material powder,
The soft magnetic material powder is Fe-based amorphous alloy atomized powder,
A dust core in which Cu is dispersed between the soft magnetic material powders. 2. The dust core according to claim 1, wherein a content of the Cu is 0.01 to 3 mass% with respect to a total mass of the soft magnetic material powder and the Cu. The dust core according to claim 1 or 2,
A coil component comprising a coil wound around the powder magnetic core. A method of manufacturing a powder magnetic core composed of soft magnetic material powder,
The soft magnetic material powder is Fe-based amorphous alloy atomized powder,
A first step of mixing the Fe-based amorphous alloy atomized powder and Cu powder;
A second step of pressure-molding the mixed powder obtained in the first step,
A method for producing a dust core, comprising obtaining a dust core in which Cu is dispersed between the Fe-based amorphous alloy atomized powder.   The method for producing a dust core according to claim 4, wherein a content of the Cu powder is 0.01 to 5 mass% with respect to a total mass of the soft magnetic material powder and the Cu powder.   The method of manufacturing a dust core according to claim 4 or 5, wherein in the first step, the soft magnetic material powder and the Cu powder are first mixed, and then a binder is added and further mixed. .

Images