Manufacturing method of powder magnetic core

Abstract

To provide a manufacturing method of powder magnetic core capable of achieving both magnetic properties and insulation properties.SOLUTION: The manufacturing method of a powder magnetic core includes: a first step of obtaining granular powder by mixing a metal magnetic powder consisting of multiple metal magnetic particles with a resin and metal soap (step S10); and a second step of obtaining a molded body by pressing and molding the obtained granulated powder (step S20). In the first step, the mixed metal soap is liquid at 25°C and contains a Zr element.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a powder magnetic core. [Background technology]

[0002] Conventionally, oxide magnetic materials such as ferrite and metal magnetic materials have been used as magnetic materials for the magnetic cores of inductors and transformers. Magnetic cores using these magnetic materials include, for example, powder magnetic cores formed by compressing metal magnetic powder. Such powder magnetic cores have a high saturation magnetic flux density and are advantageous for miniaturizing components such as inductors and transformers. Furthermore, because powder magnetic cores can be molded using a mold, there is a high degree of freedom in the shape of the magnetic core. Furthermore, even complex shapes can be manufactured with a simple process and with high precision, making their usefulness highly sought after.

[0003] For example, Patent Document 1 discloses a molding material containing a metal magnetic powder surface-treated with a zirconium-based coupling agent and a resin. The molding material disclosed in Patent Document 1 uses a metal magnetic powder surface-treated with a coupling agent, thereby improving the flowability of the molding material. By improving the flowability of the molding material, the filling ability of the compact can be increased, making it easier to form a powder magnetic core with excellent magnetic properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-135416 Summary of the Invention [Problem to be solved by the invention]

[0005] When a metal magnetic powder is used as the magnetic powder in a powder magnetic core, it is necessary to improve the insulation between the particles of the metal magnetic powder in order to prevent damage to the powder magnetic core. However, in a powder magnetic core, increasing the packing density of the metal magnetic powder to improve the magnetic properties reduces the gaps between the particles of the metal magnetic powder, which tends to reduce the insulation. Therefore, there is a problem in that it is difficult to achieve both magnetic properties and insulation in a powder magnetic core using a metal magnetic powder.

[0006] Therefore, an object of the present disclosure is to provide a method for producing a powder magnetic core that can achieve both magnetic properties and insulating properties. [Means for solving the problem]

[0007] A method for manufacturing a powder magnetic core according to one embodiment of the present disclosure includes a first step of mixing a metal magnetic powder composed of a plurality of metal magnetic particles, a resin, and a metal soap to obtain a granular granulated powder, and a second step of pressure-molding the obtained granulated powder, wherein the metal soap mixed in the first step is liquid at 25°C and contains Zr element. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to achieve both magnetic properties and insulating properties of a powder magnetic core. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view showing the configuration of an electrical component including a powder magnetic core according to an embodiment. [Figure 2] FIG. 2 is a diagram schematically showing a cross section of a powder magnetic core according to an embodiment. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing a powder magnetic core according to an embodiment. [Figure 4] FIG. 4 is a flowchart showing the steps of producing granulated powder according to the embodiment. [Figure 5]FIG. 5 is a diagram showing the relationship between breakdown voltage and magnetic permeability in samples of powder magnetic cores. [Figure 6] FIG. 6 is a diagram showing the relationship between the amount of Zr-based additive added and the magnetic permeability×breakdown voltage in the powder magnetic core samples. [Figure 7] FIG. 7 is a diagram showing the relationship between the heat treatment temperature and the breakdown voltage for the powder magnetic core samples. [Figure 8] FIG. 8 is a diagram showing the relationship between the heat treatment temperature and the magnetic permeability in the powder magnetic core samples. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings.

[0011] Note that the embodiments described below each illustrate a specific example of the present disclosure. The numerical values, shapes, materials, components, component placement positions, connection configurations, steps (processes), and order of steps (processes) shown in the following embodiments are examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in independent claims are described as optional components.

[0012] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0013] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or perpendicular, terms indicating the shape of elements, such as rectangle or rectangular parallelepiped, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0014] (Embodiment) Hereinafter, a powder magnetic core according to an embodiment and an electrical component using the powder magnetic core will be described.

[0015] [composition] First, the configuration of an electrical component using a powder magnetic core according to an embodiment will be described with reference to FIGS.

[0016] Fig. 1 is a schematic perspective view showing the configuration of an electrical component including a powder magnetic core according to an embodiment. Fig. 1 shows the general shape of a powder magnetic core 10, which will be described later, and further shows a see-through view of the interior of the powder magnetic core 10. For example, components such as a coil member 40 that are hidden by being embedded in the powder magnetic core 10 are shown with dashed lines, indicating that they can be seen through the powder magnetic core 10.

[0017] As shown in FIG. 1, the electrical component 100 includes a powder magnetic core 10, a coil member 40, a first terminal member 25, and a second terminal member .

[0018] As an example, the electrical component 100 is a rectangular parallelepiped inductor, and the approximate outer shape is determined by the shape of the powder core 10. The powder core 10 can be formed into any shape by pressure molding. In other words, the electrical component 100 can be formed into any shape depending on the shape of the powder core 10 during pressure molding. Therefore, the shape of the powder core is not limited to a rectangular parallelepiped, and other shapes are also possible.

[0019] The electrical component 100 is a passive element that stores electrical energy flowing between the first terminal member 25 and the second terminal member 35 as magnetic energy using the coil member 40. In this embodiment, the electrical component 100 will be described as one example of use of the powder magnetic core 10, but the powder magnetic core 10 can simply be used as a magnetic material, and use examples are not limited to the electrical component 100 according to this embodiment.

[0020] The powder magnetic core 10 has rectangular opposing surfaces on which the first terminal member 25 and the second terminal member 35 are respectively formed, and has a substantially square prism shape in which the four sides of each opposing surface are connected by a top surface, a bottom surface, and two side surfaces. In this embodiment, the powder magnetic core 10 has a rectangular shape with bottom and top surfaces measuring, for example, about 14.0 mm x 12.5 mm, and the distance from the bottom surface to the top surface is about 8.0 mm.

[0021] 2 is a diagram schematically showing a cross section of the powder magnetic core 10. FIG. 2 is an enlarged view of a portion of the cross section of the powder magnetic core 10.

[0022] As shown in FIG. 2, the powder magnetic core 10 has a metal magnetic powder 11 made up of a plurality of metal magnetic particles, and a binder 12 that binds the plurality of metal magnetic particles of the metal magnetic powder 11 together.

[0023] Metal magnetic powders such as Fe-Si-Al, Fe-Si, Fe-Si-Cr, Fe-Si-Cr-B, or Fe-Si-Cr-BC are used as the metal magnetic powder 11. The metal magnetic powder 11 has a higher saturation magnetic flux density than magnetic powders such as ferrite, and is therefore useful for use under large currents.

[0024] Metal magnetic powders such as Fe-Si-Al, Fe-Si, Fe-Si-Cr, Fe-Si-Cr-B, or Fe-Si-Cr-BC are used as the metal magnetic powder 11. The metal magnetic powder 11 has a higher saturation magnetic flux density than magnetic powders such as ferrite, and is therefore useful for use under large currents.

[0025] For example, when using an Fe-Si-Al-based metal magnetic powder, the composition elements are Si with a content of 8 wt% to 12 wt%, Al with a content of 4 wt% to 6 wt%, and the remaining composition elements are Fe and unavoidable impurities. Here, examples of unavoidable impurities include Mn, Ni, P, S, and C. By setting the contents of the composition elements that make up the metal magnetic powder 11 within the above composition ranges, high magnetic permeability and low coercive force can be obtained.

[0026] For example, when using an Fe-Si based metal magnetic powder, the composition elements are Si with a content of 1 wt% to 8 wt%, with the remaining composition elements being Fe and unavoidable impurities, which are the same as those described above.

[0027] For example, when using an Fe-Si-Cr based metal magnetic powder, the composition elements are Si with a content of 1 wt% to 8 wt%, Cr with a content of 2 wt% to 8 wt%, and the remaining composition elements are Fe and unavoidable impurities, which are the same as those described above.

[0028] For example, when using an Fe-Si-Cr-B based metal magnetic powder, the composition elements are Si with a content of 1 wt% to 8 wt%, Cr with a content of 2 wt% to 8 wt%, B with a content of 1 wt% to 8 wt%, and the remaining composition elements are Fe and unavoidable impurities, which are the same as those described above.

[0029] For example, when using an Fe-Si-Cr-BC based metal magnetic powder, the composition elements are Si with a content of 1 wt% to 8 wt%, Cr with a content of 2 wt% to 8 wt%, B with a content of 1 wt% to 8 wt%, C with a content of 0.01 wt% to 1 wt%, and the remaining composition elements are Fe and unavoidable impurities, such as Mn, Ni, P, and S.

[0030] The role of Si in the composition elements of the above-mentioned metal magnetic powder 11 is to reduce magnetic anisotropy and magnetostriction constant, increase electrical resistance, and reduce eddy current loss. By making the Si content in the composition elements 1 wt% or more, it is possible to obtain an improvement effect on soft magnetic properties, and by making it 8 wt% or less, it is possible to suppress a decrease in saturation magnetization and thus a decrease in DC bias characteristics.

[0031] Furthermore, the effect of improving weather resistance can be imparted by including Cr in the metal magnetic powder 11. By making the Cr content in the composition elements 2 wt% or more, the weather resistance improvement effect can be obtained, and by making it 8 wt% or less, the deterioration of soft magnetic properties can be suppressed.

[0032] The method for producing the metal magnetic powder 11 according to this embodiment is not particularly limited, and various atomization methods and various pulverization methods can be used.

[0033] The median diameter D50 of these metal magnetic powders 11 is, for example, 1.0 μm or more and 35 μm or less. In order to alleviate electric field concentration between particles, insulating properties can be ensured by making the median diameter D50 of the metal magnetic powder 11 small. Furthermore, by setting the median diameter D50 as described above, a high filling rate and ease of handling can be ensured. Furthermore, by setting the median diameter D50 of the metal magnetic powder 11 to 35 μm or less, core loss, particularly eddy current loss, can be reduced in the high-frequency range. Furthermore, the metal magnetic powder 11 may be a mixture of two or more types of powders with different median diameters D50. The median diameter D50 of the metal magnetic powder 11 is the particle diameter measured by a particle size distribution analyzer using a laser diffraction scattering method, counting from the smallest particle diameter to the total, and the cumulative value reaches 50% of the total.

[0034] The binder 12 is provided so as to cover the periphery of the metal magnetic particles of the metal magnetic powder 11. The binder 12 is located between the metal magnetic particles of the metal magnetic powder 11. The binder 12 is an insulating resin material containing resin as a main component. The binder 12 is formed, for example, from a resin and a metal soap. The binder 12 may further contain a coupling agent and / or insulating particles (for example, inorganic particles such as talc).

[0035] The resin is, for example, a thermosetting resin. Examples of thermosetting resins include epoxy resin, phenol resin, silicone resin, and polyimide resin. The resin may be a thermoplastic resin. Examples of thermoplastic resins include acrylic resin, polyethylene, polypropylene, and polystyrene. The binder 12 may contain multiple types of resins.

[0036] The binder 12 may contain Zr element derived from a metal soap. For example, the binder 12 contains, as a component containing Zr element, a metal soap containing Zr element and / or a reaction product of a metal soap containing Zr element.

[0037] Furthermore, in the powder magnetic core 10, a coating derived from a metal soap containing Zr may be formed between the metal magnetic particles of the metal magnetic powder 11 and the binder 12. This coating is formed, for example, so as to cover the entire surface of the metal magnetic particles of the metal magnetic powder 11.

[0038] Continuing with reference to FIG. 1, the coil member 40, the first terminal member 25, and the second terminal member 35 will be described.

[0039] The coil member 40 is wound with a long conductor wire coated with an insulating film (winding portion), and both ends of the wire are connected to the first terminal member 25 and the second terminal member 35, respectively (lead portions 20 and 30). In this embodiment, a round conductor wire with a cross-sectional diameter of approximately 0.65 mm is used as the conductor wire. There are no particular limitations on the thickness or shape of the conductor wire. As long as the thickness allows for winding and other processes, round conductor wires and flat conductor wires with rectangular cross sections can be appropriately selected and used. The winding portion is embedded near the center of the powder core 10. In the lead portions 20 and 30, each end of the conductor wire extends continuously from the winding portion to the opposing surfaces and protrudes outside the powder core 10. Here, portions of the lead portions are flattened and bent to fit along the opposing surfaces and the bottom surface. The insulating film coating is removed from the extended portions, allowing for electrical connection to the outside.

[0040] The first terminal member 25 and the second terminal member 35 are made of a conductive plate such as phosphor bronze or copper. Each of the first terminal member 25 and the second terminal member 35 has a recess near the center along the opposing surface and is configured to recess into the powder core 10. The lead portions 20 and 30 are disposed outside this recess. The lead portion 20 and the first terminal member 25 are electrically connected. The lead portion 30 and the second terminal member 35 are electrically connected. The lead portions 20 and 30 are connected to the first terminal member 25 and the second terminal member 35 by resistance welding or the like. The first terminal member 25 and the second terminal member 35 are bent so as to be inserted toward the inside of the powder core 10, and the first terminal member 25 and the second terminal member 35 are fixed to the powder core 10 with the bent portions inserted into the powder core 10.

[0041] Additionally, the first terminal member 25 and the second terminal member 35 are bent together with the lead portions 20 and 30 so as to fit along the bottom surface of the powder magnetic core 10. As a result, the lead portions 20 and 30 are held by the first terminal member 25 and the second terminal member 35 and routed around the underside of the bottom of the electrical component 100. In other words, the lead portions 20 and 30 can be directly connected to lands (not shown) of a mounting board or the like on which the electrical component 100 is mounted.

[0042] The first terminal member 25 and the second terminal member 35 are not essential components. If the lead portions 20 and 30 have the strength to maintain their shape independently, the first terminal member 25 and the second terminal member 35 do not have to be provided.

[0043] [Manufacturing method] Next, an example of a method for manufacturing the above-mentioned powder magnetic core 10 will be described.

[0044] FIG. 3 is a flowchart showing a method for manufacturing a powder magnetic core according to this embodiment.

[0045] 3, in the method for manufacturing the dust core 10 according to the present embodiment, first, the metal magnetic substance powder 11, resin, and metal soap are mixed together to produce a granular granulated powder containing the metal magnetic substance powder 11, resin, and metal soap (step S10). Step S10 is an example of the first step. In step S10, for example, after obtaining a mixture of the metal magnetic substance powder 11 and the metal soap, the mixture is mixed with resin to obtain a granulated powder.

[0046] 4 is a flowchart showing the steps of producing granulated powder according to this embodiment. In step S10, granulated powder is obtained by performing the steps shown in FIG.

[0047] As shown in FIG. 4, in producing the granulated powder, first, the metal magnetic powder 11 and the metal soap are mixed (step S11). This results in a mixture of the metal magnetic powder 11 and the metal soap. In step S11, the mixture does not substantially contain resin. Furthermore, the mixing in step S11 is performed at room temperature, for example, of about 25°C, without any particular temperature control such as heating or cooling. Note that if the ambient temperature is low, the mixture may be heated to a temperature of about 40°C or less before mixing in order to maintain the metal soap in a liquid state.

[0048] The metal soap contains Zr element. Specifically, the metal soap is a fatty acid zirconium. The mixed metal soap is liquid at 25°C (room temperature). That is, the melting point of the metal soap is below 25°C. Therefore, in step S11, the metal magnetic powder 11 and the liquid metal soap are mixed. The liquid metal soap has, for example, a branch in the hydrocarbon chain of the fatty acid to lower the melting point. The metal soap is produced, for example, by a direct method or a metathesis method. The direct method is a method in which a fatty acid is directly reacted with a metal oxide or metal hydroxide. The metathesis method is a method in which a basic compound is reacted with a fatty acid in an aqueous solution to form a basic compound of the fatty acid, and then a metal salt containing a metal or metalloid is reacted with the basic compound.

[0049] In this way, by mixing the metal magnetic powder 11 with the liquid metal soap before mixing with the resin, the surfaces of the metal magnetic particles of the metal magnetic powder 11 and the hydrophilic parts of the metal soap can easily interact with each other, allowing the metal soap to function effectively. In addition, because the metal soap is in liquid form, it has high dispersibility, making it easier for the metal soap to act uniformly on the surfaces of the metal magnetic particles of the metal magnetic powder 11.

[0050] In step S11, a solvent may be further added to facilitate mixing of the metal magnetic powder 11 and the metal soap. If a solvent is added, the mixture is evaporated and removed from the mixture after mixing by heating at a temperature of, for example, 65°C or higher and 150°C or lower. Examples of the solvent that can be used include toluene, xylene, ethanol, isopropyl alcohol, acetone, and methyl ethyl ketone.

[0051] Next, the mixture of metal magnetic powder 11 and metal soap obtained in step S11 is subjected to heat treatment (step S12). By such heat treatment, a strong coating derived from the metal soap is formed on the surface of the metal magnetic particles of metal magnetic powder 11. The heating method is not particularly limited, but heating is performed using a heating furnace such as an electric furnace. Note that, if the mixture is heated in step S11 to remove the solvent, the heat treatment may be performed immediately after the solvent is removed.

[0052] The heat treatment in step S12 is carried out, for example, at a temperature of 200°C or higher and 800°C or lower. This allows the heat treatment to be carried out at a temperature higher than the resin hardening temperature and at a temperature at which sintering of the metal magnetic powder 11 is unlikely to occur, thereby effectively forming a coating derived from the metal soap. From the viewpoint of enhancing the functionality of the coating derived from the metal soap, the temperature condition for the heat treatment may be 200°C or higher and 600°C or lower, or 500°C or higher and 600°C or lower. The time for the heat treatment (the time for treatment at the target temperature) is, for example, 20 minutes or higher and 120 minutes or lower.

[0053] In step S12, the mixture is heat-treated in a non-oxidizing atmosphere such as nitrogen gas, for example, which prevents the mixture from being altered due to oxidation.

[0054] In this way, in the production of granulated powder, after obtaining the mixture, the mixture is subjected to heat treatment before mixing the mixture with the resin.

[0055] Next, resin is further added to the mixture that has been heat-treated in step S12, and the mixture and resin are mixed (step S13). This results in a granular granulated powder that is a mixture of the metal magnetic powder 11, resin, and metal soap. The mixing in step S13 is performed at room temperature, for example, at about 25°C, without any temperature control such as heating or cooling.

[0056] The resin to be mixed in step S13 is used in a state in which it has been dissolved in a solvent in advance, for example. Note that the resin to be mixed in step S13 does not have to be dissolved in a solvent. As the solvent, for example, the solvents exemplified as those used in step S11 above can be used. The resin is a resin that is the main component of the binder 12 described above. Two or more types of resins may be mixed in step S13.

[0057] In step S13, the mixture heat-treated in step S12 is mixed with resin, and then heated at a temperature of, for example, 65°C to 150°C to evaporate the solvent. The mixture after solvent evaporation is pulverized to obtain a granular granulated powder (composite magnetic material) with good moldability. Furthermore, this granulated powder may be classified to obtain granulated powder with particle sizes within a predetermined range. This can further improve moldability.

[0058] The mixing in steps S11 and S13 is carried out using, for example, a mortar, a mixer, a ball mill, a V-type mixer, a cross rotary, or the like.

[0059] In step S11 and / or step S13, other materials such as a coupling agent may be further added and mixed as needed. The other materials may also include insulating particles.

[0060] In the production of granulated powder through the above-described steps, the metal magnetic substance powder 11, the resin, and the metal soap are mixed to obtain granular granulated powder containing the metal magnetic substance powder 11, the resin, and the metal soap. The obtained granulated powder can also be said to be granulated powder containing the metal magnetic substance powder 11 and the above-described binder 12.

[0061] In producing the granulated powder, the mixing ratio of the metal soap to the metal magnetic powder 11 (i.e., the ratio of the amount of metal soap added to the amount of metal magnetic powder 11 added) is, for example, 0.01 wt% or more. This effectively improves the magnetic properties and insulating properties of the powder core 10. Furthermore, from the viewpoint of further improving the magnetic properties and insulating properties of the powder core 10, the mixing ratio of the metal soap may be 0.05 wt% or more and 1 wt% or less, or 0.3 wt% or more and 1 wt% or less.

[0062] In producing the granulated powder, the mixing ratio of the resin to the metal magnetic powder 11 (that is, the ratio of the amount of resin added to the amount of metal magnetic powder 11 added) is, for example, 1 wt % or more and 10 wt % or less.

[0063] Alternatively, the granulated powder may be obtained by not performing step S12, but by mixing the mixture of the metal magnetic powder 11 that has not been subjected to heat treatment and the metal soap with the resin in step S13.

[0064] In the above, the mixing of the metal magnetic powder 11, the resin, and the metal soap is performed in separate steps S11 and S13, but this is not limited to this. The mixing procedure of the metal magnetic powder 11, the resin, and the metal soap may be different from that described above as long as a granular granulated powder containing the metal magnetic powder 11, the resin, and the metal soap is obtained. For example, the metal magnetic powder 11, the resin, and the metal soap may be mixed at once. Furthermore, a combination of materials different from the above may be mixed in two or more steps.

[0065] 3, after step S10, the granulated powder obtained in step S10 is put into a mold and subjected to pressure molding into a desired shape to obtain a powder core 10 (step S20). Step S20 is an example of the second step. In step S20, for example, a pressure of 3 ton / cm 2 More than 7ton / cm 2 The pressure molding is performed with a pressure in the following range: The pressure-molded powder core 10 is then cured, for example, by heating. The conditions for the curing process are set according to the type of resin used.

[0066] The above steps produce powder magnetic core 10. The produced powder magnetic core 10 is used as part of electric component 100 in which a coil is embedded. In addition, in step S20, granulated powder may be pressure-molded together with coil member 40.

[0067] As described above, the method for manufacturing the dust core 10 includes a first step (step S10) of mixing the metal magnetic powder 11, resin, and metal soap to obtain a granulated powder, and a second step (step S20) of pressure-molding the obtained granulated powder to obtain a compact. The metal soap mixed in the first step is liquid at 25°C and contains Zr element.

[0068] As a result, during the manufacturing process of the powder core 10, the liquid metal soap containing Zr element coats the surfaces of the metal magnetic particles of the metal magnetic substance powder 11. As a result, the metal soap containing Zr element protects the metal magnetic particles by, for example, forming a coating on the surfaces of the metal magnetic particles of the metal magnetic substance powder 11. This makes it less likely that the metal magnetic particles will come into contact with each other, improving the insulating properties of the powder core 10. Furthermore, because the metal soap improves the affinity between the metal magnetic substance powder 11 and the resin, the gaps between the metal magnetic particles of the metal magnetic substance powder 11 are more likely to be reduced during compaction, improving the magnetic properties of the powder core 10. Therefore, the manufacturing method of the powder core 10 according to this embodiment can achieve both good magnetic properties and good insulating properties for the powder core 10.

[0069] Furthermore, since the Zr element contained in the liquid metal soap is a tetravalent metal element, the number of fatty acids relative to the metal element is greater than in the case of metal soaps containing divalent or trivalent metal elements, and metal soaps containing the Zr element can further increase the affinity between the metal magnetic powder 11 and the resin.

[0070] [Evaluation of powder magnetic cores] Next, evaluation results of the powder magnetic cores according to the embodiments will be described. Specifically, the powder magnetic cores were fabricated as described below, and the characteristics of the fabricated powder magnetic cores were evaluated. Note that the present embodiments are not limited to the evaluations described below.

[0071] <Production of powder magnetic core> First, the preparation of the powder magnetic core samples used for evaluation will be described.

[0072] In preparing the samples used for evaluation, first, a metal magnetic powder, a resin, and a Zr-based additive were prepared.

[0073] The metallic magnetic powder used was Fe-Si based metallic magnetic powder.

[0074] The resin used was a modified silicone resin with methyl and phenyl groups on the side chains, dissolved in a solvent (isopropyl alcohol) in advance (concentration: 50 wt%). The amount of resin added relative to the amount of metal magnetic powder added was 3.0 wt%. Note that the amount of resin added is the amount added by weight excluding the solvent.

[0075] The Zr-based additives used were metal soaps containing Zr element (hereinafter also referred to as "Zr-containing metal soaps") or zirconium-based coupling agents (hereinafter also referred to as "Zr-based coupling agents"). The Zr-containing metal soaps used were fatty acid zirconium salts that were liquid at 25°C and had a branched hydrocarbon chain. The Zr-based coupling agents used were those that were liquid at 25°C. The amounts of Zr-based additives added relative to the amount of metal magnetic powder added were the amounts (wt%) shown in Tables 1 and 2. As shown in Table 1, no Zr-based additives were added to some samples.

[0076] Using these materials, first, a metal magnetic powder, a liquid Zr-based additive, and toluene were mixed. The mixture of the metal magnetic powder and Zr-based additive was then heated at 90°C for 90 minutes to remove the toluene, and then heat-treated for 30 minutes under the temperature conditions shown in Table 2. The heat treatment was performed under nitrogen gas. For the samples shown in Table 1, only the toluene was removed, and no heat treatment was performed. Next, resin was further added to the mixture and mixed, and the mixture was heated to remove the solvent, and then pulverized to produce granular granulated powder. In other words, the granulated powder was produced using the method described above with reference to Figure 4.

[0077] The granulated powder was heated at room temperature for 4 ton / cm 2 The resin was pressed at a pressure of 1000 kJ / cm2, and a ring core with an outer diameter of 14.4 mm, an inner diameter of 10.3 mm, and a thickness of 4.4 mm was produced for evaluation of magnetic permeability. The ring core was then dried at a temperature of 150°C for 2 hours to harden the resin, thereby producing a ring-shaped powder magnetic core sample.

[0078] The granulated powder was then heated at room temperature for 4 ton / cm2 The resin was then pressed at a pressure of 1200 kJ / cm2 to produce a plate-shaped compact measuring 12 mm in length, 12 mm in width, and 0.70 mm in thickness for evaluation of breakdown voltage. The plate-shaped compact was then dried at 150°C for 2 hours to harden the resin, thereby producing a plate-shaped powder core sample.

[0079] <Method of calculating magnetic permeability> The magnetic permeability was determined by measuring the inductance L of the ring-shaped powder core using an LCR meter in an applied magnetic field of 0 oersted (Oe), and calculating the initial magnetic permeability (magnetic permeability μi below) using the following formula (1) (measurement frequency: 100 kHz). A high magnetic permeability μi indicates that the magnetic properties of the powder core are good.

[0080] μi=(L×le) / (μ0×Ae×n 2 ) ···(1)

[0081] Here, le is the effective magnetic path length, μ0 is the magnetic permeability of a vacuum, Ae is the cross-sectional area, and n is the number of turns of the measuring coil.

[0082] <Evaluation method for breakdown voltage> To measure the breakdown voltage, which is an indicator of insulation, a plate-shaped powder core sample was sandwiched between conductive rubber on both main surfaces, and an initial DC voltage of 10 V was applied. The applied voltage was then increased continuously at a rate of 5 V / min, and the breakdown voltage of each powder core was determined by dividing the applied voltage just before breakdown occurred by the thickness of the compact (V / mm). A high breakdown voltage indicates high insulation properties of the powder core.

[0083] <Evaluation result 1> First, the results of evaluating the magnetic properties and insulating properties by changing the type and amount of Zr-based additive used to prepare the granulated powder will be described with reference to Table 1, FIGS. 5 and 6.

[0084] Table 1 shows the type and amount of Zr-based additive, magnetic permeability, breakdown voltage, and the value obtained by multiplying magnetic permeability and breakdown voltage (magnetic permeability × breakdown voltage) for each powder magnetic core sample used in the evaluation. FIG. 5 shows the relationship between breakdown voltage and magnetic permeability for the samples shown in Table 1. In other words, FIG. 5 is a graph of the data in Table 1. In FIG. 5, the vertical axis represents magnetic permeability, and the horizontal axis represents breakdown voltage. FIG. 6 shows the relationship between the amount of Zr-based additive added and magnetic permeability × breakdown voltage for the samples shown in Table 1. In FIG. 6, the vertical axis represents magnetic permeability × breakdown voltage, and the horizontal axis represents the amount of Zr-based additive added. It can be said that a sample with a higher magnetic permeability × breakdown voltage is one that is able to achieve both better magnetic properties and better insulation properties. 5 and 6, the evaluation results of sample A1, which did not use a Zr-based additive ("no Zr-based additive" in the legend in the figure), the evaluation results of samples B1 and B2, which used a Zr-based coupling agent as a Zr-based additive ("Zr-based coupling agent" in the legend in the figure), and the evaluation results of samples C1 to C5, which used a Zr-containing metallic soap ("Zr-containing metallic soap" in the legend in the figure), are shown with markers of different shapes. Furthermore, each marker in Figure 5 is labeled with the identification code of the sample.

[0085] [Table 1]

[0086] As shown in Table 1, sample A1 is a sample to which no Zr-based additive was added. Samples B1 and B2 are samples prepared using a Zr-based coupling agent as the Zr-based additive, with the amount of Zr-based coupling agent added being varied. Samples C1 to C5 are samples prepared using a Zr-containing metallic soap as the Zr-based additive, with the amount of Zr-containing metallic soap added being varied. As described above, the samples shown in Table 1 were not subjected to heat treatment in the production of the granulated powder.

[0087] As shown in Table 1 and Figure 5, samples C1 to C5, which use Zr-containing metallic soap as a Zr-based additive, have higher magnetic permeability and breakdown voltage than sample A1, which does not contain a Zr-based additive. In this way, adding Zr-containing metallic soap in the production of granulated powder improves both the magnetic properties and insulating properties, achieving a balance between magnetic properties and insulating properties.

[0088] Furthermore, compared to samples B1 and B2, which used a Zr-based coupling agent as the Zr-based additive, samples C1 to C5, which used a Zr-containing metallic soap, showed a significant increase in breakdown voltage relative to sample A1. Therefore, it can be said that using a Zr-containing metallic soap as a Zr-based additive is more effective in improving the insulation properties of powder magnetic cores than using a Zr-based coupling agent.

[0089] Because Zr-containing metallic soap has a long hydrocarbon chain, it has a higher affinity with resins than Zr-based coupling agents, making it easier to close the gaps between metal magnetic particles during molding.This is thought to be why the magnetic permeability improved in powder magnetic cores that use Zr-containing metallic soap.In addition, Zr-containing metallic soap is more likely to be present on the surfaces of metal magnetic particles, such as by forming a coating on the surfaces of metal magnetic particles more easily than Zr-based coupling agents, which is why the breakdown voltage improved in powder magnetic cores that use Zr-containing metallic soap.

[0090] Furthermore, as shown in Figure 6, when a Zr-containing metallic soap is used as the Zr-based additive, the value of magnetic permeability x breakdown voltage can be increased compared to when a Zr-based coupling agent is used as the Zr-based additive, even when the amount of Zr-based additive added is small.The results shown in Figure 6 show that when the amount of Zr-containing metallic soap added is 0.01 wt% or more, the magnetic permeability x breakdown voltage is higher than when a Zr-based coupling agent is used as the Zr-based additive.

[0091] <Evaluation result 2> Next, the results of evaluation of the magnetic properties and insulating properties of samples that were heat-treated in the production of granulated powder will be described with reference to Table 2, FIGS. 7 and 8.

[0092] Table 2 shows the type and amount of Zr-based additive, heat treatment temperature, magnetic permeability, breakdown voltage, and the value obtained by multiplying magnetic permeability and breakdown voltage (magnetic permeability × breakdown voltage) for each powder magnetic core sample used in the evaluation. FIG. 7 is a graph showing the relationship between the heat treatment temperature and breakdown voltage for the samples shown in Table 2. FIG. 8 is a graph showing the relationship between the heat treatment temperature and magnetic permeability for the samples shown in Table 2. In other words, FIGS. 7 and 8 are graphs of the data in Table 2. In FIG. 7, the vertical axis represents breakdown voltage, and the horizontal axis represents the heat treatment temperature for the heat treatment of the mixture of the metal magnetic powder and the Zr-based additive. In addition, in FIG. 8, the vertical axis represents magnetic permeability, and the horizontal axis represents the heat treatment temperature for the heat treatment of the mixture of the metal magnetic powder and the Zr-based additive. In addition, in Figures 7 and 8, the evaluation results of samples B2, B3, and B4, which contained 0.50 wt% of Zr-based coupling agent as a Zr-based additive ("0.5 wt% Zr-based coupling agent" in the legend in the figures), the evaluation results of samples C1, C6, and C7, which contained 0.05 wt% of Zr-containing metallic soap ("0.05 wt% Zr-containing metallic soap" in the legend in the figures), and the evaluation results of samples C3, C8, and C9, which contained 0.50 wt% of Zr-containing metallic soap ("0.5 wt% Zr-containing metallic soap" in the legend in the figures), are shown with markers of different shapes.

[0093] [Table 2]

[0094] Table 2 also shows the evaluation results of some of the samples of the powder magnetic cores shown in Table 1. The same samples in Table 2 as those in Table 1 are given the same identification symbols.

[0095] As shown in Table 2, samples B3 and B4 were prepared by using 0.50 wt% of a Zr-based coupling agent as a Zr-based additive and varying the heat treatment temperature. Samples C6 and C7 were prepared by using 0.05 wt% of a Zr-containing metallic soap as a Zr-based additive and varying the heat treatment temperature. Samples C8 and C9 were prepared by using 0.50 wt% of a Zr-containing metallic soap as a Zr-based additive and varying the heat treatment temperature.

[0096] As shown in Table 2, Figures 7 and 8, samples B3 and B4, which were heat-treated mixtures of metal magnetic powder and Zr-based coupling agent, had higher breakdown voltages but lower magnetic permeabilities than sample B2, which was not heat-treated.

[0097] On the other hand, samples C6 to C9, which were heat-treated mixtures of metal magnetic powder and Zr-containing metallic soap, exhibited higher breakdown voltages and magnetic permeabilities than samples C1 and C3, which were not heat-treated. In other words, heat treatment of a mixture of metal magnetic powder and Zr-containing metallic soap improves both the insulating and magnetic properties. The improved insulating properties are thought to be due to the Zr-based additives being immobilized on the surfaces of the metal magnetic particles through heat treatment to form a coating, thereby suppressing contact between the metal magnetic powder. The improved magnetic properties are thought to be due to the Zr-containing metallic soap being immobilized on the surfaces of the metal magnetic particles through heat treatment to form a coating, effectively increasing the affinity between the metal magnetic powder and the resin, making it easier to reduce the gap between the metal magnetic particles during molding.

[0098] <Summary> The above evaluation results of the powder magnetic cores showed that by mixing liquid Zr-containing metallic soap with metal magnetic powder at 25°C when producing the granulated powder, the magnetic permeability and breakdown voltage of the powder magnetic core increased, making it possible to achieve both the magnetic properties and insulating properties of the powder magnetic core.

[0099] Furthermore, it was found that by subjecting a mixture of Zr-containing metallic soap and metallic magnetic powder to heat treatment in the production of granulated powder, the magnetic permeability and breakdown voltage of the powder core can be further increased, and the magnetic properties and insulating properties of the powder core can be further improved.

[0100] (Other embodiments, etc.) Although the powder magnetic core according to the embodiment of the present disclosure has been described above, the present disclosure is not limited to this embodiment.

[0101] For example, the present disclosure also includes electrical components using the above-described powder magnetic cores. Examples of electrical components include inductance components such as high-frequency reactors, inductors, and transformers. The present disclosure also includes power supply devices equipped with the above-described electrical components.

[0102] Furthermore, the present disclosure is not limited to the above-described embodiments, and various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of one or more aspects, as long as they do not deviate from the spirit of the present disclosure.

[0103] Below, an example of the method for manufacturing a powder magnetic core according to the present disclosure, which has been described based on the above embodiment, will be shown. The method for manufacturing a powder magnetic core according to the present disclosure is not limited to the following example.

[0104] For example, a method for manufacturing a powder magnetic core according to a first aspect of the present disclosure includes a first step of mixing a metal magnetic powder composed of a plurality of metal magnetic particles, a resin, and a metal soap to obtain a granular granulated powder, and a second step of pressure-molding the obtained granulated powder, wherein the metal soap mixed in the first step is liquid at 25°C and contains Zr element.

[0105] Also, for example, a method for manufacturing a powder magnetic core according to a second aspect of the present disclosure is the method for manufacturing a powder magnetic core according to the first aspect, wherein in the first step, the mixing ratio of the metal soap to the metal magnetic powder is 0.01 wt% or more.

[0106] Furthermore, for example, a method for manufacturing a powder magnetic core according to a third aspect of the present disclosure is a method for manufacturing a powder magnetic core according to the first or second aspect, in which, in the first step, a mixture is obtained by mixing the metal magnetic powder and the metal soap, and then the mixture is mixed with the resin to obtain the granulated powder.

[0107] Furthermore, for example, a method for producing a powder magnetic core according to a fourth aspect of the present disclosure is the method for producing a powder magnetic core according to the third aspect, wherein in the first step, after obtaining the mixture, the mixture is heat-treated at a temperature of 200°C or higher and 800°C or lower before mixing the mixture with the resin.

[0108] Furthermore, for example, a method for producing a powder magnetic core according to a fifth aspect of the present disclosure is the method for producing a powder magnetic core according to the fourth aspect, wherein the temperature condition for the heat treatment is 500°C or higher and 600°C or lower.

[0109] Furthermore, for example, a method for producing a powder magnetic core according to a sixth aspect of the present disclosure is the method for producing a powder magnetic core according to the fourth or fifth aspect, wherein in the first step, the heat treatment is carried out in a non-oxidizing atmosphere. [Industrial Applicability]

[0110] The powder magnetic core according to the present disclosure can be used as a material for the magnetic core of high-frequency inductors, transformers, and the like. [Explanation of symbols]

[0111] 10 powder magnetic core 11 Metal magnetic powder 12 Binder 20, 30 Lead section 25 First terminal member 35 Second terminal member 40 Coil material 100 Electrical Components

Claims

1. A first step of mixing a metal magnetic powder composed of a plurality of metal magnetic particles, a resin, and a metal soap to obtain a granulated powder; A second step of press-molding the obtained granulated powder, In the first step, the metal soap to be mixed is liquid at 25°C and contains Zr element. A method for manufacturing a powder magnetic core.

2. In the first step, the mixing ratio of the metal soap to the metal magnetic powder is 0.01 wt % or more. A method for producing the powder magnetic core according to claim 1.

3. In the first step, the metal magnetic substance powder and the metal soap are mixed to obtain a mixture, and then the mixture is mixed with the resin to obtain the granulated powder. The method for producing the powder magnetic core according to claim 1 or 2.

4. In the first step, after obtaining the mixture, the mixture is subjected to a heat treatment under a temperature condition of 200° C. or more and 800° C. or less before mixing the mixture with the resin. The method for producing the powder magnetic core according to claim 3 .

5. The temperature condition of the heat treatment is 500°C or higher and 600°C or lower. The method for producing the powder magnetic core according to claim 4 .

6. In the first step, the heat treatment is performed in a non-oxidizing atmosphere. The method for producing the powder magnetic core according to claim 4 .

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