JP5372481B2 - Powder magnetic core and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the dust core which exhibits excellent ring compression strength and magnetic characteristics even if low-pressure molding is carried out at room temperature. <P>SOLUTION: Powder of an amorphous soft magnetic alloy consists of 85 wt.% of first powder having mean particle diameter of 42 &mu;m, and the reminder of 15 wt.% of second powder of different granularity having mean particle diameter of 4-6 &mu;m. Powder of a plurality kinds of amorphous soft magnetic alloy is mixed with 5 wt.% of low melting point glass having mean particle diameter of 0.8-10.0 &mu;m for the powder of amorphous soft magnetic alloy, mixed with insulating resin binder, dried, and passed through a sieve having sieve mesh of 300 &mu;m for coating. The mixture containing powder of an amorphous soft magnetic alloy coated with the insulating resin binder is then mixed with lubricative resin and pressure molded with molding pressure of 1300 MPa at room temperature to form a molding. The molding thus formed is annealed at 480&deg;C for 30 minutes. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a dust core used for a smoothing choke coil or the like and a method for manufacturing the same.

  With the increase in performance and functionality of various electronic devices, currents have increased, and soft magnetic materials used for magnetic cores such as choke coils used in such electronic devices have characteristics that have small characteristic changes even at large currents, that is, excellent DC superimposition and low loss are required.

  Ferrite cores and dust cores are used as choke coils used at high frequencies. Among these, the ferrite core has a defect that the saturation magnetic flux density is small. On the other hand, a dust core produced by molding metal alloy powder has a higher saturation magnetic flux density than soft magnetic ferrite, and thus has excellent DC superposition characteristics.

  As this metal alloy powder, Sendust, which is an alloy of silicon, aluminum, and iron, Permalloy, which is an alloy of nickel and iron, silicon steel, which is an alloy of silicon and iron, and the like are used. Further, the use of an amorphous alloy, which is an amorphous soft magnetic alloy, has been studied as a lower loss alloy.

  In order to produce a powder magnetic core using this amorphous soft magnetic alloy powder, the amorphous soft magnetic alloy powder is mixed with a low-melting glass and an organic binder and compression molded at a high pressure, followed by heat treatment. The method is known.

  For example, as a conventional technique, as in Patent Document 1, a method of performing high-density molding with a mold and powder at a high temperature during molding, or as disclosed in Patent Document 2, a metal alloy powder is made of a low-melting glass and an organic binder. There is a method of mixing and molding at high pressure at room temperature.

  However, in the methods of Patent Document 1 and Patent Document 2, a low-melting glass powder is fixed on the surface of the amorphous soft magnetic alloy powder, which is higher than the softening point of the glass and higher than the crystallization temperature of the amorphous soft magnetic alloy powder. Also, pressure molding is performed at a low temperature. However, the powder magnetic cores produced by these methods have weak mechanical strength, and there is a problem that the powder magnetic core is damaged such as a step of winding the powder magnetic core and a step of mounting.

  Therefore, as in Examples 3, 6, and 12 of Patent Document 3, two types of amorphous soft magnetic alloy powders, glass powders, and binder resins having different particle sizes are formed, and amorphous soft magnetic particles are formed in the atmosphere. A method of firing at a temperature lower than the crystallization temperature of the magnetic alloy powder is known. This method is a method in which a powder having a small particle size fills a gap between powders having a large particle size, thereby increasing the molding density and increasing the mechanical strength and magnetic properties of the dust core even when the molding pressure is low.

JP-A-10-212503 JP 2001-73062 A JP 2006-176817 A

  However, the dust ring strength of the dust core obtained by the method of Patent Document 3 can be obtained only less than about 15 MPa, and it is difficult to say that it is a strong dust core. In addition, in this method, in order to obtain an amorphous soft magnetic alloy powder having a small particle size, the amorphous soft magnetic alloy is embrittled in a hydrogen atmosphere, and then the embrittled amorphous Since this method pulverizes a soft magnetic alloy, the process becomes complicated and is not suitable for mass production. Furthermore, there has been a problem that, by grinding, distortion occurs in the fine powder and hysteresis loss increases.

  As described above, a powder magnetic core made of amorphous soft magnetic alloy powder has problems such as poor formability compared to other metals and weak mechanical strength despite its excellent magnetic properties. . In addition, since the powder itself is hard, a sufficient density cannot be obtained even if the pressure during molding is increased, and excellent magnetic properties cannot be obtained.

  An object of the present invention is to solve the above-mentioned problems and, like conventional metal alloys, even if low-pressure molding is performed at room temperature, the mechanical strength is strong, and the powder magnetic core has a soft magnetic property and a method for producing the powder magnetic core Is to provide.

Based on the above object, the dust core of the present invention comprises a composite magnetic material powder in which two or more kinds of amorphous soft magnetic alloy powders having different average particle diameters are uniformly dispersed, and an amorphous soft magnetic alloy powder having a softening point. The glass powder having a temperature lower than the crystallization temperature of the mixture is mixed, and the resulting mixture is mixed with a methylphenyl silicone resin and a lubricating resin, whereby two or more kinds of the amorphous soft magnetic alloy powder in the mixture are mixed. And the glass powder are coated, and the coated mixture and a lubricating resin are mixed. The resulting mixture is pressure-molded to produce a molded body, and the molded body is formed into the amorphous soft magnetic alloy. In the powder magnetic core formed by annealing at a temperature lower than the crystallization temperature of the powder, the glass powder is bismuth-based glass or phosphate-based glass, and is produced by performing the annealing treatment in the air. Features.

  In another aspect of the present invention, the glass powder has an average particle size of 0.8 to 10 μm.

  In another aspect of the present invention, the addition amount of the glass powder to the amorphous soft magnetic alloy powder is 2 to 5 vol%.

  In another aspect of the present invention, the amount of the lubricating resin added to the amorphous soft magnetic alloy powder is 0.1 to 2.0 wt%.

  In another embodiment of the present invention, the lubricating resin is a material selected from stearic acid, stearate, stearic acid soap, and ethylene bisstearamide.

In addition, after mixing two or more kinds of amorphous soft magnetic alloy powders having different average particle sizes as described above and glass powder having a softening point lower than the crystallization temperature of the amorphous soft magnetic alloy powder, methylphenyl silicone is used. A manufacturing method for obtaining a dust core excellent in mechanical strength and magnetic properties by coating with a resin, press-molding, and heat-treating in the air is also an embodiment of the present invention.

  According to the present invention as described above, the amorphous soft magnetic alloy powder and the low-melting glass are mixed, covered with a binding insulating resin, mixed with a lubricating resin, and then subjected to pressure molding and annealing treatment. By performing in the air, the surface of the amorphous soft magnetic alloy powder is oxidized, and the binding strength between the low-melting glass and the soft magnetic alloy powder increases. It is possible to provide a dust core excellent in mechanical strength and a method for producing a dust core.

The manufacturing method of the powder magnetic core of the present embodiment includes the following steps.
(1) A first mixing step in which two or more kinds of amorphous soft magnetic alloy powders having different average particle diameters are mixed with low-melting glass.
(2) A coating step of coating the mixture that has undergone the first mixing step with a binding insulating resin.
(3) A second mixing step of mixing the lubricating resin with the composite soft magnetic powder coated with the binding insulating resin and the low melting point glass.
(4) A molding step for producing a molded body by subjecting the mixture that has undergone the second mixing step to pressure molding.
(5) An annealing process for annealing the molded body that has undergone the molding process.
Hereafter, each process is demonstrated concretely.

(1) First mixing step In the first mixing step of the present embodiment, 85 wt% of the amorphous soft magnetic alloy powder is used as the first powder having an average particle size of 42 μm, and the remaining 15 wt% is used as the particle size. The second powder has different average particle diameters of 4 to 6 μm. Further, a low melting point glass having an addition amount of 2 to 5 vol% with respect to the volume of the amorphous soft magnetic alloy powder is mixed for 2 hours using a mixer (V-type mixer).

(2) Coating process The coating process which coat | covers the mixture which passed through the said mixing process with binder insulating resin mixes a binder insulating resin with the mixture which passed through the mixing process, and dries. Then, it is passed through a sieve having an opening of 300 μm. In the coating step, a lubricating resin may be mixed. In this case, the addition amount should not exceed 2.0 wt% with respect to the soft magnetic alloy powder that is amorphous in total with the lubricating resin mixed with the soft magnetic alloy powder that is amorphous in the mixing step. To.

  An acrylic acid copolymer resin (EAA) emulsion is used as the binding insulating resin used in the coating process. The addition amount of the acrylic acid copolymer resin (EAA) emulsion to be mixed is 2.0 wt% with respect to the amorphous soft magnetic alloy powder. In this case, the drying temperature and drying time are 2 hours at 80 ° C. It is.

  This acrylic acid copolymer resin (EAA) emulsion is a soap-free colloidal emulsion in which various crosslinking agents and physical property-imparting agents are blended. An acrylic acid copolymer resin (EAA) emulsion forms a film having a cross-linked structure that is not redissolved in water and hardly absorbs moisture when water is evaporated by heat drying. This film is tacky and works optimally as a binder during molding. The addition amount of acrylic acid copolymer resin (EAA) emulsion is an appropriate amount of 0.5 to 2.0 wt%. If it is less than this, the strength of the molded body will be insufficient and cracks will occur. On the other hand, if the amount is more than 2.0 wt%, there arises a problem that the maximum density reduction due to density reduction and the magnetic characteristics due to an increase in hysteresis loss are reduced.

  Further, instead of the acrylic acid copolymer resin (EAA) emulsion, a methylphenyl silicone resin or a PVA (polyvinyl alcohol) aqueous solution (12% aqueous solution) may be used. The addition amount of methylphenyl silicone resin is an appropriate amount of 0.5 to 2.0 wt%. The addition amount of PVA (polyvinyl alcohol) aqueous solution (12% aqueous solution) is an appropriate amount of 0.5 to 3.0 wt%.

  When a methylphenyl silicone resin or a PVA (polyvinyl alcohol) aqueous solution (12% aqueous solution) is used, if the amount is less than the appropriate amount, the strength of the molded body is insufficient and cracking occurs. On the other hand, when the amount is more than the appropriate amount, there arises a problem that the maximum magnetic flux density is lowered due to the density reduction and the magnetic characteristics are lowered due to the increase in hysteresis loss. The average particle size of the powder is preferably equal to or less than the average particle size of the second powder soft magnetic alloy powder. If it is larger than this, the density will be reduced.

(3) Second Mixing Step In the second mixing step of mixing the lubricating resin with the mixture that has undergone the coating step, the binder insulating resin is mixed with the first mixture in which the lubricating resin is mixed. Lubricating resin in an amount of 0.5 wt% based on the total amount of the composite soft magnetic powder coated with the binding insulating resin and the low melting point glass is mixed for 2 hours using a mixer (V-type mixer).

  As the lubricating resin used in the second mixing step, a wax such as stearic acid, stearate, stearic acid soap, ethylene bisstearamide, or the like is used. Specific examples include ethylene bisstearamide, lithium stearate, and aluminum stearate. In this case, the addition amount of the lubricating resin is 0.1 to 2.0 wt% with respect to the amorphous soft magnetic alloy powder. If it is less than this, a sufficient effect cannot be obtained, and if it is more than this, there arises a problem that the maximum magnetic flux density is reduced due to density reduction and the magnetic characteristics are lowered due to increase in hysteresis loss.

(4) Molding step In the molding step, the soft magnetic alloy coated with the binder as described above is press-molded at a molding pressure of 1300 MPa at room temperature to form a molded body. At this time, the pressure-dried binding insulating resin acts as a binder during molding.

(5) Annealing process In an annealing process, a powder magnetic core is produced by performing an annealing process with respect to the said molded object at 480 degreeC for 30 minutes. Here, the heat treatment is performed at 480 ° C. in order to maintain a certain degree of crushing strength below the crystallization temperature of the amorphous soft magnetic alloy powder. On the other hand, if the annealing temperature is raised too much, the magnetic properties are deteriorated due to the deterioration of the insulation performance, and in particular, the eddy current loss is greatly increased, thereby suppressing the iron loss from increasing.

  At this time, the binding insulating resin is thermally decomposed when it reaches a certain temperature during the annealing process. By performing the heat treatment of the dust core in the atmosphere, the binding insulating resin becomes a film covering the powder of the soft magnetic alloy that is amorphous. Therefore, even if heat treatment is performed at a high temperature, the insulation does not deteriorate and hysteresis loss due to oxidation does not increase. It also serves to improve mechanical strength.

  When the low melting point glass is heated to a temperature higher than the softening point, it softens and exhibits fluidity. The low melting point glass exhibiting fluidity penetrates so as to fill the gaps between the particles of the amorphous soft magnetic alloy powder, thereby increasing the molding density of the dust core. Further, the molded dust core functions as a strong binder and gives mechanical strength to the dust core. Furthermore, it also functions as an insulating agent between the amorphous soft magnetic alloy powders, thereby preventing and suppressing the generation of eddy currents.

Next, Examples 1 to 14 of the present invention will be described below with reference to FIGS. 1 to 4 and Tables 1 to 6.
[1. Measurement item]
As measurement items, permeability, maximum magnetic flux density, and direct current superimposition are measured by the following method. The magnetic permeability was calculated from the inductance at 100 kHz and 0.5 V by applying a primary winding (20 turns) to the produced powder magnetic core and using an impedance analyzer.

  The maximum magnetic flux density is obtained by applying a primary winding (170 turns) and a secondary winding (20 turns) to a dust core, and using a BH analyzer (Iwatori Measurement Co., Ltd .: SY-8232) as a magnetic measurement instrument. The magnetic flux density at an applied magnetic field H = 20000 A / m was measured. In addition, direct current superimposition is performed by applying a primary winding (170 turns) to each dust core and using an LCR meter (HP: 4284A) capable of measuring inductance, capacitance, and resistance. The inductance at each DC bias at 5 V was measured, and the magnetic permeability was determined by calculation.

[2. First characteristic comparison (comparison of addition amount of low melting point glass)]
In the first characteristic comparison, the amount of low melting point glass added to the amorphous soft magnetic alloy powder was compared. The sample used for the first characteristic comparison was prepared as follows. Table 1 is a table showing the types and components of the low-melting glass added to the soft magnetic alloy powder that is amorphous as a comparative example and an example in the present embodiment. Each low melting point glass has an average particle size of 0.9 to 11.0 μm.

  First, 85 wt% of the amorphous soft magnetic alloy powder is used as a first powder having an average particle size of 42 μm, and the remaining 15 wt% is used as a second powder having an average particle size of 4 μm having different particle sizes. Further, 5 wt% of low melting point glass of amorphous soft magnetic alloy powder is mixed for 2 hours using a mixer (V-type mixer).

  Next, an acrylic acid copolymer resin (EAA) emulsion is mixed as a binding insulating resin. The addition amount of the acrylic acid copolymer resin (EAA) emulsion is 2.0 wt% with respect to the amorphous soft magnetic alloy powder, and then drying is performed at 80 ° C. for 2 hours. Then, it is passed through a sieve having an opening of 300 μm. This was press-molded at a pressure of 1300 MPa at room temperature to produce a dust core. And these powder magnetic cores were annealed at 480 ° C. for 30 minutes.

The relationship of the amount of low melting point glass added in the first characteristic comparison is as follows. In Comparative Examples 1 to 11, the amount of addition of low melting point glass having an average particle size of 0.9 μm to 2.9 μm to the amorphous soft magnetic alloy powder is changed, and the sinter treatment is performed in a nitrogen atmosphere. This is a comparative example. Comparative Examples 1 to 3 are Bi ₂ O ₃ —ZnO—B ₂ O ₃ , which is a bismuth glass having an average particle diameter of 1.1 μm as described in Table 1, and Comparative Examples 4 to 7 are tables. Bi ₂ O ₃ —B ₂ O ₃ , which is a bismuth-based glass having an average particle size of bismuth-based 2 described in 1 of 0.9 μm, Comparative Examples 8 to 11 are the average of phosphoric acid-based 1 described in Table 1. SnO—P ₂ O ₅ , which is a phosphate glass having a particle size of 2.9 μm, was added as a low melting point glass.

  In Examples 1 to 11, the amount of addition of low melting point glass having an average particle size of 0.9 μm to 2.9 μm to the powder of amorphous soft magnetic alloy is changed, and squeezing treatment is performed in the air. This is an example. In Examples 1 to 3, bismuth system 1 described in Table 1 was added, in Examples 4 to 7 bismuth system 2 described in Table 1 and phosphoric acid system 1 described in Table 1 were added as low melting glass, respectively. .

Tables 2 to 4 are tables showing the relationship between the particle size and content of the low-melting glass, the relative density of the dust core, and the crushing strength for Examples 1 to 11 and Comparative Examples 1 to 11. 1 to 3 are graphs showing the relationship between the amount of low melting point glass added and the crushing strength.

As can be seen from Table 2, when Bi ₂ O ₃ —B ₂ O ₃ , which is a bismuth glass having an average particle size of 1.1 μm, is used as the low-melting glass, Examples 1 to 3 in which the annealing process was performed in the air It can be seen that the crushing strength of the dust core is higher when the content of the low-melting glass is 0.9 to 4.7 vol% than in Comparative Examples 1 to 3 in which the annealing process is performed in a nitrogen atmosphere. . In addition, it can be seen from FIG. 2 that the crushing strength of the dust core is increased by performing the annealing process in the air and increasing the amount of low-melting glass added. The crushing strength of the dust core can be increased by adding low melting point glass, and the crushing strength of the dust core can be increased to 10 MPa or more when the addition amount is 0.9 vol or more. In particular, a crushing strength of 20 MPa or more can be obtained with an addition amount of 2 vol% or more. However, when the addition amount is 5 vol or more, the relative density is lowered and the magnetic properties of the dust core are lowered.

As can be seen from Table 3, when Bi ₂ O ₃ —ZnO—B ₂ O ₃ , which is a bismuth glass having an average particle size of 0.9 μm, is used as the low-melting glass, Example 4 in which the annealing process was performed in the air. In the case of ~ 7, the crushing strength of the powder magnetic core is higher when the content of the low-melting glass is 1.1 to 4.4 vol% than in Comparative Examples 4 to 7 in which the annealing process is performed in a nitrogen atmosphere. I understand. In addition, it can be seen from FIG. 2 that the crushing strength of the dust core is increased by performing the annealing process in the air and increasing the amount of low-melting glass added. The crushing strength of the dust core can be increased by adding low-melting glass, and a crushing strength of 20 MPa or more can be obtained particularly when the addition amount is 2 vol% or more. However, when the addition amount is 5 vol or more, the relative density is lowered and the magnetic properties of the dust core are lowered.

As can be seen from Table 4, when SnO—P ₂ O ₅ , which is a phosphate glass having an average particle diameter of 2.9 μm, is used as the low melting point glass, Examples 8 to 11 in which the annealing process was performed in the air. However, it turns out that the crushing intensity | strength of a powder magnetic core becomes high in content of low melting glass 1.3-3.8 vol% rather than Comparative Examples 8-11 which performed the annealing process in nitrogen atmosphere. Moreover, it can be seen from FIG. 3 that the crushing strength of the dust core is increased by performing the annealing process in the air and increasing the amount of low-melting glass added. The crushing strength of the dust core can be increased by adding low-melting glass, and a crushing strength of 20 MPa or more can be obtained particularly when the addition amount is 2 vol% or more. However, when the addition amount is 5 vol or more, the relative density is lowered and the magnetic properties of the dust core are lowered.

  As described above, the low melting point glass is added to the amorphous soft magnetic alloy powder, and the annealing process is performed in the atmosphere, so that the surface of the amorphous soft magnetic alloy powder is oxidized and the low melting point glass is oxidized. Since the binding strength between the soft magnetic alloy powder and the soft magnetic alloy powder increases, it is possible to produce a dust core having a high crushing strength even if low pressure molding is performed at room temperature.

[3. Second characteristic comparison (comparison of particle size of low melting point glass)]
In the second characteristic comparison, the particle size of the low-melting glass added to the amorphous soft magnetic alloy powder was compared. The sample used for the second characteristic comparison was prepared as follows. First, 85 wt% of the amorphous soft magnetic alloy powder is used as a first powder having an average particle size of 42 μm, and the remaining 15 wt% is used as a second powder having an average particle size of 4 μm having different particle sizes. Furthermore, Bi ₂ O ₃ —ZnO—B ₂ O ₃ , which is a low-melting glass having an average particle size of 0.8 to 11 μm of 5 wt% of amorphous soft magnetic alloy powder, was mixed (V-type mixer). ) For 2 hours.

  Next, an acrylic acid copolymer resin (EAA) emulsion is mixed as a binding insulating resin. The addition amount of the acrylic acid copolymer resin (EAA) emulsion is 2.0 wt% with respect to the amorphous soft magnetic alloy powder, and then drying is performed at 80 ° C. for 2 hours. Then, it is passed through a sieve having an opening of 300 μm. This was press-molded at a pressure of 1300 MPa at room temperature to produce a dust core. And these powder magnetic cores were annealed at 480 ° C. for 30 minutes.

The relationship of the addition amount of the low melting point glass in the second characteristic comparison is as follows. In Comparative Examples 12 to 15, low melting point glass having an average particle size of 0.8 μm to 11.0 μm was added in an amount of 3.3 vol% of amorphous soft magnetic alloy powder and subjected to a tempering treatment in a nitrogen atmosphere. It is a comparative example. In Examples 12 to 15, low melting point glass having an average particle size of 0.8 μm to 11.0 μm was added in an amount of 3.3 vol% of amorphous soft magnetic alloy powder, and annealing treatment was performed in the air. It is an example.

As can be seen from Table 5, when Bi ₂ O ₃ —ZnO—B ₂ O ₃ , which is a bismuth-based glass having an average particle diameter of 0.8 to 11.0 μm, is used as the low-melting glass, the annealing step is performed in the air. It can be seen that Examples 12 to 15 have higher crushing strength of the dust core than Comparative Examples 12 to 15 in which the annealing process was performed in a nitrogen atmosphere. Moreover, it turns out that the intensity | strength of the crushing intensity | strength of a powder magnetic core falls by making a low melting point glass particle size larger than 0.8 micrometer from FIG. In particular, in comparison between Example 15 and Comparative Example 15 in which the particle size of the low-melting glass is larger than 10 μm, the crushing strength of the dust core of Example 15 is 10 MPa or less, and the crushing strength of the dust core is the same as that of Comparative Example 15. The difference becomes smaller. Further, processing the particle size of the low melting point glass to 0.8 μm or less cannot be performed by the dry pulverization method. Although it is possible with the wet pulverization method, there is a problem that the solvent remains in the low melting point glass.

  As described above, by adding a low-melting glass to the amorphous soft magnetic alloy powder and performing the annealing process in the atmosphere, the surface of the amorphous soft magnetic alloy powder is oxidized, and the nonmagnetic layer Therefore, even if low pressure molding is performed at room temperature, a dust core having high crushing strength can be produced. It can be seen that the particle size of the low melting point glass in that case is preferably between 0.8 and 10.0 μm.

[4. Third characteristic comparison (comparison of magnetic characteristics of dust cores)]
In the third characteristic comparison, low melting point glass was added to the amorphous soft magnetic alloy powder, and the magnetic characteristics of the dust cores were compared when the annealing process was performed in air or nitrogen. The sample used in the third property comparison is a low melting glass used in the property comparison, Bi ₂ O ₃ -B ₂ O ₃ , which is a bismuth-based glass having an average particle size of 1.1 μm, and is soft. The powder magnetic cores of Comparative Example 3 and Example 3 in which 4.7 vol% is added to the magnetic alloy powder and the annealing process is performed in the air or in a nitrogen atmosphere are used.

As can be seen from Table 6, when Bi ₂ O ₃ —B ₂ O ₃ , which is a bismuth-based glass having an average particle diameter of 1.1 μm, is used as the low melting point glass, Example 3 in which the annealing process was performed in the air was better. It can be seen that the permeability at 100 kHz is low and there is almost no difference in core loss.

  From the above, by adding low melting point glass to amorphous soft magnetic alloy powder and performing the annealing process in the air, the surface of amorphous soft magnetic alloy powder is oxidized and nonmagnetic layer increases. By doing so, a strong magnetic powder core can be produced.

[Other Embodiments]
The present invention is not limited to the embodiment described above. Other embodiments such as the following are also included.

(A) The first powder used in the embodiment is not limited to an average particle size of 45 μm, and may have an average particle size in the range of 30 to 100 μm, but the average particle size is larger than this range. On the other hand, if the average particle size is smaller than this range, the hysteresis loss due to density reduction increases.

(B) Amorphous soft magnetic alloy powder produced by the water atomization method may be used as the second powder among the amorphous soft magnetic alloy powder. The water atomization method is a kind of metal powder manufacturing method, and can obtain a soft magnetic powder that has a flat surface and is relatively close to a sphere. It is possible to produce a magnetic core.

(C) The lubricating resin used in the present embodiment may be a wax such as ethylene bisstearite, lithium stearate, aluminum stearate or zinc stearate. By adding the lubricating resin, the slip between the amorphous soft magnetic powders can be improved, so that the density during mixing can be improved and the molding density can be increased. That is, the action of the lubricating resin can provide a dust core having excellent DC superposition characteristics and magnetic characteristics even when low pressure molding is performed at room temperature.

(D) The present invention is not limited to the dust core produced in the embodiment as described above, and includes an embodiment in which a choke coil is produced by winding a coil around the dust core. . As a result, the effects obtained in the first to eleventh embodiments as described above can be similarly achieved in the choke coil.

The graph which showed the change of the crushing intensity | strength of the powder magnetic core at the time of changing the addition amount of the low melting glass (bismuth type | system | group 1) in the 1st characteristic comparison of the Example of this invention. The graph which showed the change of the crushing intensity | strength of the powder magnetic core at the time of changing the addition amount of the low melting glass (bismuth type | system | group 2) in the 1st characteristic comparison of the Example of this invention. The graph which showed the change of the crushing intensity | strength of the powder magnetic core at the time of changing the addition amount of the low melting glass (phosphoric acid type 1) in the 1st characteristic comparison of the Example of this invention. The graph which showed the change of the crushing intensity | strength of the powder magnetic core at the time of changing the particle size of the low melting glass (bismuth type | system | group 3) in the 2nd characteristic comparison of the Example of this invention.

Claims (10)

A composite magnetic material powder in which two or more kinds of amorphous soft magnetic alloy powders having different average particle diameters are uniformly dispersed and a glass powder having a softening point lower than the crystallization temperature of the amorphous soft magnetic alloy powder are mixed,
The obtained mixture is mixed with a methylphenyl silicone resin and a lubricating resin to coat two or more kinds of the amorphous soft magnetic alloy powder and the glass powder in the mixture, and the coating is further performed. The obtained mixture is mixed with a lubricating resin, and the resulting mixture is pressure-molded to produce a molded body, and the molded body is annealed at a temperature lower than the crystallization temperature of the amorphous soft magnetic alloy powder. In the dust core
The glass powder is bismuth glass or phosphate glass,
A dust core produced by performing the annealing treatment in the air.   The dust core according to claim 1, wherein the glass powder has an average particle size of 0.8 to 10 μm.   3. The dust core according to claim 1, wherein an addition amount of the glass powder to the amorphous soft magnetic alloy powder is 2 to 5 vol%.   The dust core according to any one of claims 1 to 3, wherein an amount of the lubricating resin added to the amorphous soft magnetic alloy powder is 0.1 to 2.0 wt%.   The pressure according to any one of claims 1 to 4, wherein the lubricating resin is a material selected from stearic acid, stearate, stearic acid soap, and ethylene bisstearamide. Powder magnetic core. A mixing step of mixing the amorphous soft magnetic alloy powder and a glass powder having a softening point lower than the crystallization temperature of the amorphous soft magnetic alloy powder;
A coating step in which the mixture obtained in the mixing step is mixed with a methylphenyl silicone resin and a lubricating resin to coat two or more kinds of the amorphous soft magnetic alloy powder and the glass powder in the mixture ;
A molding step in which a mixture obtained by mixing a lubricating resin with the mixture obtained in the coating step is subjected to pressure molding treatment to produce a molded body; and
In the method for producing a powder magnetic core having an annealing step of annealing the molded body that has undergone the molding step at a temperature lower than the crystallization temperature of the amorphous soft magnetic alloy powder,
The glass powder is bismuth glass or phosphate glass,
A method of manufacturing a dust core, wherein the annealing step is performed in the atmosphere.   The method for producing a dust core according to claim 6, wherein the glass powder has an average particle size of 0.8 to 10 μm.   The method for manufacturing a dust core according to claim 6 or 7, wherein an addition amount of the glass powder to the amorphous soft magnetic alloy powder is 2 to 5 vol%.   The amount of the lubricating resin added to the amorphous soft magnetic alloy powder is 0.1 to 2.0 wt%, and the dust core according to any one of claims 6 to 8, Production method.   The pressure according to any one of claims 6 to 9, wherein the lubricating resin is a material selected from stearic acid, stearate, stearic acid soap, and ethylene bisstearamide. Manufacturing method of a powder magnetic core.

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