Magnetic material

Abstract

The present disclosure provides a magnetic material which is a sintered body comprising a metal magnetic body and a metal oxide or a metal nitride obtained by oxidizing or nitriding a non-magnetic metal, the metal oxide or the metal nitride being dispersed in the metal magnetic body, and the filling rate of the metal magnetic body being 81.4-99.2%.

Description

Technical Field

[0001] The present disclosure relates to magnetic materials. Background Art

[0002] Composite magnetic materials are sometimes used as magnetic materials for magnetic components, etc. One example of such composite magnetic materials is a resin containing soft magnetic powder and the like in a dispersed state (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-143827 Summary of the Invention

[0006] When a composite magnetic material contains a resin, if an electric current flows through a magnetic component having a blank and wiring containing the magnetic material, local concentration of magnetic flux occurs between the powder particles of the soft magnetic powder in the magnetic material, thereby increasing eddy current losses and possibly leading to deterioration of high-frequency characteristics.

[0007] An object of the present disclosure is to provide a magnetic material capable of achieving improved high-frequency characteristics.

[0008] In order to achieve the above object, the present disclosure provides a magnetic material.

[0009] It is a sintered body containing a metal magnetic body and a metal oxide or metal nitride formed by oxidation or nitridation of a non-magnetic metal.

[0010] The metal oxide or the metal nitride is dispersed in the metal magnetic body.

[0011] The filling rate of the metal magnetic body is 81.4% to 99.2%.

[0012] According to the present disclosure, it is possible to improve high-frequency characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a photograph of the magnetic material disclosed herein.

[0014] Figure 2 is with Figure 1 Corresponding schematic diagram.

[0015] Figure 3 This is a perspective view schematically showing an electronic component including one embodiment of the magnetic material disclosed herein.

[0016] Figure 4 yes Figure 3Schematic cross-sectional view between line segment a-a.

[0017] Figure 5 This is a perspective view schematically showing an electronic component according to another embodiment. DETAILED DESCRIPTION

[0018] Below, with reference to the attached Figure 1 While the following description will refer to the accompanying drawings as needed, the contents of the drawings are merely schematic and illustrative for understanding the present invention, and the appearance, dimensional ratios, etc. may differ from the actual objects.

[0019] Figure 1 This is a photograph schematically showing the magnetic material of the present disclosure. Figure 2 is with Figure 1 Corresponding schematic diagram.

[0020] Because conventional magnetic materials comprising soft magnetic powder dispersed in resin may have deteriorated high-frequency characteristics, the inventors of the present application conducted intensive research on a new magnetic material having a different structure from the conventional magnetic materials and thus came up with the present invention.

[0021] Specifically, if Figure 1 and Figure 2 As shown, the magnetic material 5 of the present disclosure is a sintered body 3 including a metal magnetic body 1 and a metal oxide or metal nitride 2 obtained by oxidizing or nitriding a non-magnetic metal.

[0022] In the present disclosure, the metal oxide or metal nitride 2 is dispersed in the metal magnetic body 1. Furthermore, in the present disclosure, the filling rate of the metal magnetic body 1 in the magnetic material 5 is 81.4% to 99.2%.

[0023] Because the metal oxide or metal nitride 2 is formed by oxidizing or nitriding a non-magnetic metal, its resistivity may be higher than that of the aforementioned magnetic metal. For example, the resistivity of the metal oxide or metal nitride may range from 1×10^11 Ω·cm to 1×10^16 Ω·cm. Alternatively, the resistivity of the magnetic metal may range from 0.089 μΩ·m to 1.76 μΩ·m. Furthermore, the metal oxide or metal nitride 2 itself may be non-magnetic.

[0024] The metal magnetic material 1 described above contains the element Fe. Furthermore, the metal oxide or metal nitride 2 dispersed in the metal magnetic material 1 can be selected from at least one of Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb, and Ta, elements that are more easily oxidized than Fe. The area ratio of the metal oxide or metal nitride 2 in the magnetic material 5 disclosed herein can be 0.8% to 17.1%. The porosity of the magnetic material 5 disclosed herein can be 0% to 1.5%.

[0025] Figure 3 This is a perspective view schematically showing an electronic component including the magnetic material of the present disclosure. Figure 4 yes Figure 3 Schematic cross-sectional view between line segment a-a.

[0026] like Figure 3 and Figure 4 As shown, electronic component 100 includes a green body 10 containing the magnetic material 5 of the present disclosure, wiring 20, and external electrodes 30 and 40. By including the magnetic material 5 of the present disclosure, green body 10 includes a sintered body 11. Sintered body 11 itself has at least one metallic magnetic sintered layer. As an example, green body 10 can have a hexahedral structure. In addition to external electrodes 30 and 40, an insulating coating layer 60 can also be provided covering the surface of green body 10.

[0027] It should be noted that in the aforementioned sintered body 11, when metal magnetic layers of the same composition are continuously stacked, the boundaries between the metal magnetic layers are difficult to discern. Therefore, even a sintered body comprising multiple metal magnetic layers is treated as a single sintered body unless the first insulating layer, described below, is interposed between them. Furthermore, even when multiple metal magnetic layers of different compositions are stacked and distinguishable, they are treated as a single sintered body unless the first insulating layer, described below, is interposed between them.

[0028] As an example, the wiring 20 can be provided in the base body 10. The wiring 20 is a conductive material, for example, at least one selected from silver, copper, aluminum, etc. As the form of the wiring 20, in one example, Figure 3 The wiring shown may be a straight line. However, the wiring may be a coiled line. External electrodes 30 and 40 are provided on the surface of the base body 10. These external electrodes are connected to both ends of the wiring 20, and are spaced apart and arranged opposite each other via the base body 10.

[0029] Since the green body 10 includes the magnetic material 5 disclosed herein, it contains a relatively high-resistance metal oxide or metal nitride. This increases the resistance of the path of eddy current flowing through the sintered body 11 of the green body 10, thereby reducing eddy current losses. Since these eddy current losses increase with higher frequencies, reducing these losses improves high-frequency characteristics.

[0030] In the present disclosure, the filling rate of the metal magnetic material 1 in the magnetic material 5 is 81.4% to 99.2%, and the filling rate of the metal magnetic material 1 in the sintered body 11 of the green body 10 can also be within the same range. By having a filling rate of the metal magnetic material 1 of 81.4% or greater, the magnetic permeability, or in other words, the inductance value (L value), can be appropriately ensured in the electronic component 100. Furthermore, by having a filling rate of the metal magnetic material 1 of 99.2% or less, the portion of the magnetic material 5 other than the metal magnetic material (0.8% or greater), excluding voids, contains relatively high-resistance metal oxides or metal nitrides. This reduces the eddy current loss described above.

[0031] Furthermore, in the present disclosure, the area ratio of the metal oxide or metal nitride 2 in the magnetic material 5 is 0.8% to 17.1%, and the area ratio of the metal oxide or metal nitride 2 in the sintered body 11 of the green body 10 can also be within the same range. Therefore, the electrical conductivity of the sintered body 11 as a whole can be reduced, and the Joule loss of the metal magnetic sintered body can be reduced. Furthermore, in the present disclosure, the porosity of the magnetic material 5 is 0% to 1.5%, and the porosity of the sintered body 11 of the green body 10 can also be within the same range. Therefore, the space factor of the metal magnetic material can be appropriately ensured for the sintered body 11 as a whole. As a result, the reduction in the storable magnetic energy can be suppressed, and the DC superposition characteristics can be improved.

[0032] like Figure 3 and Figure 4 As shown, the green body 10 includes a sintered body 11 and a first insulating layer 13. The first insulating layer 13 can be formed in a continuous layer form from one side to the other side of the sintered body 11 in a direction intersecting the stacking direction L. With this form, two or more sintered bodies 11 divided by the first insulating layer 13 can be provided.

[0033] In this case, the green body 10 has two or more sintered bodies 11 and a first insulating layer 13, and the adjacent sintered bodies 11 and the adjacent sintered bodies 11 can be stacked with the first insulating layer 13 interposed therebetween. By configuring the first insulating layer 13, a magnetic gap function can be provided compared to a case where it is not configured. In addition, the first insulating layer 13 is preferably non-magnetic. As a result, it is possible to achieve an improvement in the DC superposition characteristics brought about by a reduction in the magnetic permeability of the green body 10. It should be noted that this is not limited to the above, and the first insulating layer 13 may not be non-magnetic, but may be a low-magnetic-permeability insulating layer having a lower magnetic permeability than the sintered body 11. In this case, it is also possible to achieve an improvement in inductance compared to the non-magnetic case.

[0034] The first insulating layer is not limited to a first insulating layer; wiring 20 may also be covered with an insulator. In this structure, the portion of wiring 20 other than the ends connected to the external electrodes 30 and 40 is directly surrounded by the insulator. This allows the insulator to function as a magnetic gap. Furthermore, the insulator is preferably nonmagnetic.

[0035] This improves the DC superposition characteristics by reducing the magnetic permeability of the green body 10. However, this is not limiting, and the insulator may not be non-magnetic, but may be a low-permeability insulator with a lower magnetic permeability than the sintered body 11. In this case, the inductance can also be improved compared to the non-magnetic case.

[0036] The first insulating layer 13 may be provided in two or more layers separated from each other. Figure 3 and Figure 4 In the illustrated embodiment, the green body 10 includes four sintered bodies 11. In this case, the wiring 20 is arranged between the first insulating layers 13, and the green body 10 may include three or more sintered bodies 11. Furthermore, providing two or more first insulating layers 13 allows for a stacked structure in which two or more sintered bodies 11 and first insulating layers 13 are alternately stacked. Providing two or more first insulating layers 13 further provides a magnetic gap function, and if the magnetic permeability of each insulating layer 13 is lower than that of the sintered body 11, the DC superposition characteristics can be further improved.

[0037] In addition, if Figure 3 and Figure 4 As shown, when the green body 10 has two or more sintered bodies 11, the first external electrode 30 and the second external electrode 40 are arranged on different surfaces of the sintered bodies 11. With the arrangement of the external electrodes 30 and 40, the green body 10 may further include a second insulating layer 50.

[0038] Specifically, the first external electrode 30 and the second external electrode 40 are disposed on the surfaces of adjacent sintered bodies 11, with the first external electrode 30 disposed on the surface of one sintered body 11 and the second external electrode 30 disposed on the surface of the other sintered body 11. In this configuration, a second insulating layer 50 can be disposed between the sintered body 11 on which the first external electrode 30 is disposed and the sintered body 11 on which the second external electrode 40 is disposed. The provision of this second insulating layer 50 prevents short circuits between the first external electrode 30 and the second external electrode 40.

[0039] In one example, the second insulating layer 50 is arranged to extend in a direction intersecting, for example, perpendicular to, the extending direction of the first insulating layer 13, and may be a slit-shaped structure. It should be noted that the second insulating layer 50 is not arranged to penetrate and divide the wiring within the base body 10.

[0040] It should be noted that in the present disclosure, the wiring does not necessarily need to be arranged inside the blank. Figure 5 As shown, the wiring 20A may be arranged in a state of being wound around the outside of the base body 10A.

[0041] Hereinafter, a method for producing an electronic component including the magnetic material of the present disclosure will be described.

[0042] <Metal Magnetic Particle Preparation Step>

[0043] First, metal magnetic particles (e.g., FeNiCo particles) containing an Fe component are prepared. Then, in one example, a sol-gel method is used to hydrolyze a metal alkoxide containing a non-magnetic metal element that is more easily oxidized than Fe and a solvent (water, alcohol, etc.) in a slurry prepared by mixing the metal alkoxide. The slurry is then dried to obtain metal magnetic particles whose surface is covered with a coating containing an element that is more easily oxidized than Fe. At this time, a metal alkoxide containing a non-magnetic metal element different from the non-magnetic metal material used in the coating of the first layer can be further used to form a second layer of coating on the coating of the first layer. The coating can be one layer, two layers, or more than three layers.

[0044] Metal alkoxides are represented by the chemical formula M(OR) x (M: non-magnetic metal element, OR: alkoxy group). The metal species M constituting the metal alkoxide may be at least one selected from Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb, and Ta.

[0045] Although not particularly limited, the metal alkoxide is preferably an alkoxide of at least one selected from the group consisting of Si, Ti, Al, and Zr. In this specification, Si, which is generally referred to as a semimetal, is treated as a metal element.

[0046] When the metal alkoxide is an alkoxide of at least one selected from the group consisting of Si, Ti, Al, and Zr, a metal oxide having higher strength and higher resistivity can be formed.

[0047] The alkoxy group OR constituting the metal alkoxide is not particularly limited and may be, for example, an alkoxy group having 10 or less carbon atoms, particularly 5 or less carbon atoms, and more particularly 3 or less carbon atoms. The smaller the number of carbon atoms, the easier the hydrolysis reaction is. The alkoxy group is preferably at least one selected from the group consisting of a methoxy group, an ethoxy group, and a propoxy group.

[0048] Specifically, the metal alkoxide is preferably at least one selected from tetraethyl orthosilicate, titanium tetraisopropoxide, zirconium n-butoxide, and aluminum isopropoxide.

[0049] The slurry may contain a water-soluble polymer. The water-soluble polymer may be selected from polyvinyl pyrrolidone, polyvinyl alcohol, hydroxypropyl cellulose, poly (2-methyl-2- At least one of oxazoline, polyethyleneimine, polyacrylic acid and carboxymethyl cellulose.

[0050] It should be noted that this is not limited to the sol-gel method described above; a coating containing an element that is more easily oxidized than Fe can also be formed on the surface of the metal magnetic particles. Furthermore, the metal magnetic particles themselves can further contain an element that is more easily oxidized than Fe as a component. Furthermore, a metal nitride component can be imparted to the surface of the metal magnetic particles. It should be noted that metal oxides and metal nitrides of non-magnetic metals are naturally non-magnetic.

[0051] <Metal Magnetic Paste Preparation Process>

[0052] After the above-mentioned metal magnetic particles are prepared, the metal magnetic particles, varnish, and a solvent (eg, terpineol) are mixed with a stirrer and then dispersed with a roll mill to obtain a metal magnetic paste.

[0053] <Insulation paste preparation process>

[0054] Prepare non-magnetic insulator particles. Then, use a blender to mix the insulator particles, varnish, and a solvent (e.g., terpineol). Then, use a roller mill to disperse the mixture to obtain an insulator paste. Examples of non-magnetic insulators used in the insulator paste include a mixture of a dielectric material such as aluminum oxide, silicon dioxide, glass, calcium zirconate, strontium zirconate, and / or barium zirconate, and borosilicate glass.

[0055] Wiring paste preparation process

[0056] Conductive particles, varnish, and a solvent (e.g., terpineol) are mixed using a stirrer and then dispersed using a roll mill to obtain a wiring paste. Conductive particles can be selected from copper particles, silver particles, and the like.

[0057] <Preparation Step of Unfired Laminated Body>

[0058] After preparing the respective pastes, the aforementioned metal magnetic paste is used to form a metal magnetic layer of a predetermined thickness, for example, by screen printing, and then dried. After drying, a slit groove of a predetermined width is formed by laser processing, and the aforementioned insulating paste is then filled into the slit groove by screen printing or other methods, and then dried. The slit groove is not limited to post-processing using laser processing; a pre-patterned pattern can also be formed using a screen printing plate or the like.

[0059] After the slit grooves are filled with an insulating paste and dried, an insulating layer of a predetermined thickness is formed on the metal magnetic layer using the insulating paste by screen printing and dried. The insulating paste used to form the insulating layer may be of a different type than the insulating paste used to fill the slit grooves.

[0060] Using a wiring paste, wiring of a desired shape (e.g., a straight shape, a coil shape, a meandering shape, etc.) is formed thereon by screen printing. In the case of forming a coil-shaped wiring, a through-hole pattern that connects the wiring pattern to the wiring pattern is formed on a plurality of metal magnetic layers using a wiring paste. The through-hole pattern can be formed by pre-forming a hole in the metal magnetic layer using laser processing or the like and then filling it with a wiring paste. After the wiring is formed, an insulating layer can be further formed thereon. By repeatedly performing the above formation of the metal magnetic layer and the formation of an arbitrary insulating layer, an unfired laminate is obtained.

[0061] It should be noted that in the resulting electronic component, if the L value exceeds the desired characteristics, the number of insulating layers can be reduced or removed. This allows for adjustment of the balance between the L value and the DC superposition characteristics. Furthermore, the above method involves laminating screen-printed layers formed using a screen printing method, but the present invention is not limited to this method. Separate sheets can also be prepared and laminated.

[0062] <Unfired Laminated Body Singulation and Firing Steps>

[0063] The unfired laminated body is cut into individual pieces using a slicer or the like, and then the individual pieces are degreased in a calcining furnace using a nitrogen atmosphere, and then calcined at a temperature of 900 to 1000 degrees Celsius for a predetermined time (e.g., 1 hour) in a reducing atmosphere of H2:3% / N2:97%. In this way, the calcined laminated body comprising the green body (sintered body) and the insulating layer of the magnetic material disclosed herein can be obtained. In the obtained calcined laminated body, an oxide or nitride of an element that is more easily oxidized than Fe may be contained in the sintered body as the green body. It should be noted that even elements that are more difficult to oxidize than Fe can be oxidized in other steps and then contained in the calcined laminated body.

[0064] In addition, the above is based on the premise of forming a non-magnetic insulating layer, but by extending the holding time of the maximum temperature during the above calcination, the metal magnetic component can be diffused from the metal magnetic layer into the non-magnetic insulating layer to obtain an insulating layer with low magnetic permeability and a little magnetism.

[0065] <Formation of External Electrodes>

[0066] The outer surface of the sintered body is then coated with an insulating resin or the like, and the coating is removed from the portion where the wiring is connected to the external electrodes using a laser or the like. Plating is then performed to form the external electrodes, ultimately completing the electronic component. The external electrodes can be made of silver, for example.

[0067] Example

[0068] Hereinafter, embodiments of the present disclosure will be described.

[0069] <Acquisition of B-H data (for simulation)>

[0070] First, metal magnetic particles, varnish (resin type: ethyl cellulose, product name: ETHOCEL), and terpineol as a solvent were mixed in a mortar. The resulting paste was oven-dried to evaporate the solvent, and the dried product was passed through a mesh to produce granulated powder. The granulated powder was then press-molded at 80°C and 120 MPa for 2 minutes to produce a toroidal core and a cylindrical sample, respectively. After degreasing in a nitrogen atmosphere, the mixture was calcined at 900°C for 60 minutes in a reducing atmosphere of H2:3% / N2:97%, resulting in a toroidal core and cylindrical sample consisting of a metallic magnetic sintered body.

[0071] The toroidal core was wound, and the magnetic permeability μ (100 Hz) was measured using an impedance analyzer E4990A (Keysight). The cylindrical sample was measured using a vibrating sample magnetometer VSM-5 (Toei Kogyo Co., Ltd.), and the saturation magnetic flux density Bs (16,000 Oe) was measured. The measured μ and Bs were substituted into the following formula to calculate the B-H data.

[0072] B=Bs×tanh(4π×10 －7 ×μ×H / Bs)

[0073] Bs is calculated using the density of the metal material (Fe: 7.87 g / cm 3 , Ni: 8.9g / cm 3 , Co: 8.9g / cm 3 ) and the composition ratio of each alloy to calculate the alloy density. The calculated alloy density is as follows.

[0074] Fe10Ni20Co:8.16g / cm 3

[0075] <Obtaining electrical conductivity (for simulation)>

[0076] Metal magnetic particles, a varnish (resin type: ethyl cellulose, product name: ETHOCEL), and a solvent, terpineol, were mixed in a mortar. The resulting paste was then printed onto an alumina substrate using a metal mask in a size of 30 mm x 5 mm x 0.2 mm. The printed material was degreased in a nitrogen atmosphere and then calcined at 900 degrees Celsius for 60 minutes in a reducing atmosphere of 3% H2 / 97% N2. The electrical conductivity was calculated using the four-probe method for resistance measurement.

[0077] <Calculation of Metal Magnetic Material Filling Factor, Void Ratio, and High-Resistance Portion Area Ratio (for Simulation)>

[0078] Each calcined sample was fixed with resin and ground using a Tegramin-25 milling device (manufactured by Struers). Ion milling was then performed using an ion milling device IM-3000 (manufactured by Hitachi High Technologies Co., Ltd.). SEM images and elemental mapping images were then acquired using a field emission scanning electron microscope SU8230 (manufactured by Hitachi High-Technologies Co., Ltd.). The acquisition magnification was 2000x. These acquired images were analyzed using the image analysis software WinROOF2021 (manufactured by Mitani Shoji Co., Ltd.) and the area ratios were calculated.

[0079] The average value of the analytical values ​​at three random locations around the 1 / 2 of the sintered toroidal core's thickness is used. Note that when calculating the final electronic component, the average value of the analytical values ​​at six locations, including three random locations at a position equal to one times the wiring thickness upward from the top surface of the internal wiring and three random locations at a position equal to one times the wiring thickness downward from the bottom surface of the internal wiring, is used. The visualization method for high-resistance portions will be described later.

[0080] <Simulation conditions and model>

[0081] The simulation used Femtet (registered trademark) from Murata Software Co., Ltd. The software used was Femtet 2022. The solver was magnetic field analysis (harmonic analysis), and the option was set to "Calculate inductance." The model was three-dimensional, with a standard mesh size of 0.03 mm.

[0082] The B-H curve for the magnetic material uses the values ​​calculated above. Note that the B-H curve uses the portion with a relative magnetic permeability μr of 1 or greater to prevent it from falling below the permeability of a vacuum. The Femtet2022 function further extrapolates the permeability to the vacuum. The conductivity of the magnetic material uses the values ​​calculated above, and the iron loss is "Joule loss only (calculated based on the current distribution)." The wiring is made of silver.

[0083] As an electronic component model, a silver linear wiring (length, width, and thickness of 1.0 mm, 0.0625 mm, and 0.02 mm) was formed inside a green body with a length dimension (L), width dimension (W), and height dimension (T) of 1.0 mm, 0.5 mm, and 0.629 mm, 0.315 mm from the bottom surface and at the center of the width dimension. Furthermore, non-magnetic insulating layers (length, width, and thickness of 1.0 mm, 0.5 mm, and 0.002 mm) were formed in contact with the upper and lower surfaces of the linear wiring. Furthermore, a non-magnetic insulating layer (width of 0.01 mm) was formed in the center of the long side dimension (L), dividing the sintered body into two between the two external electrodes.

[0084] Although simulation is used this time, electronic components can be manufactured through the following steps.

[0085] Related Examples 1 to 12 and Comparative Example 1

[0086] <Metal Magnetic Particle Preparation Step>

[0087] First, Fe10Ni20Co particles with a D50 particle size of 0.40 μm are prepared. Next, Si alkoxide and a solvent (water) are mixed together using a sol-gel method to prepare a slurry, and the alkoxide is hydrolyzed in the slurry. Then, by drying the slurry, metal magnetic particles having a surface covered with a sol-gel coating containing Si are obtained. The target film thickness described later is appropriately set by adjusting the amount of Si alkoxide. The D50 particle size is not particularly limited and can be 0.40 μm to 3.10 μm.

[0088] <Metal Magnetic Paste Preparation Process>

[0089] After the above-mentioned metal magnetic particles are prepared, the metal magnetic particles, varnish, and terpineol as a solvent are mixed with a stirrer and then dispersed with a roll mill to obtain a metal magnetic paste.

[0090] <Insulation paste preparation process>

[0091] Non-magnetic insulating particles of aluminum oxide with a D50 particle size of approximately 0.1 to 0.5 μm and non-magnetic insulating particles of borosilicate glass with a D50 particle size of approximately 0.1 to 0.5 μm were prepared. These insulating particles, varnish, and terpineol as a solvent were then mixed in a blender. The mixture was then dispersed using a roll mill to obtain an insulating paste.

[0092] Wiring paste preparation process

[0093] Silver particles having a D50 particle size of about 1 to 5 μm, varnish, and terpineol as a solvent were mixed with a stirrer and then dispersed with a roll mill to obtain a wiring paste.

[0094] <Preparation Step of Unfired Laminated Body>

[0095] After preparing the pastes, the metal magnetic paste is screen-printed to form a metal magnetic layer of a predetermined thickness and dried. After drying, a slit groove of a predetermined width is formed by laser processing, and the insulator paste is filled into the slit groove by screen printing or other methods, and dried.

[0096] After the slit groove is filled with the insulating paste and dried, an insulating layer having a predetermined thickness is formed thereon by screen printing using the above-mentioned insulating paste and dried.

[0097] Using the wiring paste, wiring of a desired shape is formed thereon by screen printing. By forming the metal magnetic material layer and the insulating layer as described above, an unfired laminate is obtained.

[0098] <Unfired Laminated Body Singulation and Firing Steps>

[0099] The unfired laminate is cut into individual pieces using a slicer or the like. These pieces are then degreased in a calcining furnace in a nitrogen atmosphere and then calcined at 900°C for one hour in a reducing atmosphere of H2:3% / N2:97%. This produces a sintered laminate having a high-resistance portion and an insulating layer within.

[0100] <Formation of External Electrodes>

[0101] Then, the outer surface of the sintered body is coated with an insulating resin, the coating of the portion connecting the wiring to the external electrode is removed by laser, and then plating is performed to form the external electrode. The material of the external electrode can be silver, for example.

[0102] An electronic component is obtained through the above operations.

[0103] Table 1 shows the results of actual sintered materials produced by firing the metal magnetic paste as described in the "Metal Magnetic Paste Preparation Process" and "Unfired Laminated Body Singulation and Firing Process" sections, not simulations. Sintered materials alone were produced without wiring or insulating layers. Table 2 shows the simulation results using the measured data in Table 1.

[0104] As the judgment criteria, the inductance (L) at 100 Hz is set to be greater than 9 nH, and ΔL (the rate of change of the inductance (L) at 100 kHz relative to the inductance (L) at 100 Hz) is set to be greater than -7%. The situation where both judgment criteria are met is set to the overall judgment of 0 (suitable).

[0105] [Table 1] Measurement results 1

[0106]

[0107] [Table 2] Measurement results 2

[0108]

[0109] In the electronic component obtained through the above operation, the sintered body (magnetic material), which is a component of the green body, consists of a metallic magnetic body and Si oxides dispersed within the metallic magnetic body. The filling ratio of the metallic magnetic body in the sintered body ranges from 81.4% to 99.2%. In contrast, Comparative Example 1, which does not use SiO2, achieves the highest electrical conductivity. Consequently, the Joule loss, or eddy current loss, of the resulting metallic magnetic sintered body increases, resulting in a ΔL of -7.8%, resulting in an overall rating of -.

[0110] In contrast, in Examples 1 to 12, compared with Comparative Example 1, there are Si oxides dispersed in the high-resistance portion of the metal magnetic body. Specifically, the area ratio of the high-resistance portion is 0.8% to 17.1%. Therefore, the electrical conductivity decreases, and at the same time, the Joule loss of the obtained metal magnetic sintered body decreases. Therefore, in any one of Examples 1 to 12, ΔL is greater than -7%. In addition, the metal magnetic body is filled in the metal magnetic sintered body within a specified range, specifically, the filling rate is 81.4% to 99.2%, so the magnetic permeability is also ensured to be above the specified value (above 25). As a result, the inductance (L) at 100 Hz is ensured to be greater than 9 nH. Based on the above, in any one of Examples 1 to 12, the comprehensive judgment is 0.

[0111] The following method can be used to visualize the high-resistance portion. Specifically, each calcined sample is fixed with resin, ground using a Tegramin-25 grinding machine (manufactured by Struers), then processed using FIB (focused ion beam) to a shape suitable for subsequent SPM (scanning probe microscopy) measurement, and finally cleaned using Ar flat milling.

[0112] Using this processed sample, the spread was measured in the SPM's SSRM (Scanning Spreading Microscope) mode. In SSRM mode, a conductive probe is scanned across the sample while applying a bias voltage, converting the current flowing through each point into a resistance value, thereby visualizing high-resistance areas.

[0113] It should be noted that in this case, the portion having a resistance value that is 10^3 times or more of the maximum measured resistance value of the metal magnetic body is defined as a high resistance portion, and its threshold value can be appropriately adjusted by referring to the element mapping image so as to match the position of high resistance materials such as oxides and nitrides.

[0114] Figure 1 This image, taken at a 2000x magnification, visualizes the SiO2, a high-resistance portion, in the sintered body produced in this example. The colored portion represents elemental mapping of the Si element. The remaining portions are the metal magnetic material or voids. At this point, even using a microscope, the grain boundary phases of the metal magnetic particles within the metal magnetic material cannot be identified.

[0115] This can be explained by the fact that the metal magnetic particles, the material of the metal magnetic body, undergo grain growth, and adjacent metal magnetic particles push SiO2 away from each other while sintering. As a result, it is believed that the SiO2 applied to the metal magnetic particles during production does not remain in the grain boundary phase of the metal magnetic particles, but instead aggregates and solidifies after sintering at locations where it was in contact with three or more metal magnetic particles before composite. In this way, the high-resistance particles are dispersed in the sintered body, thereby suppressing eddy current losses in the sintered body. Therefore, it is known that a sintered body with high magnetic permeability can be produced even at high frequencies.

[0116] The present invention includes the following aspects, but is not limited to these aspects.

[0117] <1>

[0118] A magnetic material is a sintered body comprising a metal magnetic body and a metal oxide or metal nitride formed by oxidation or nitridation of a non-magnetic metal.

[0119] The metal oxide or the metal nitride is dispersed in the metal magnetic body.

[0120] The filling rate of the metal magnetic body is 81.4% to 99.2%.

[0121] <2>

[0122] The magnetic material according to <1>, wherein the metal magnetic body contains Fe element,

[0123] The above-mentioned metal oxide or the above-mentioned metal nitride is an oxide or nitride of at least one metal selected from Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb and Ta, which are elements more easily oxidized than Fe.

[0124] <3>

[0125] The magnetic material according to <1> or <2>, wherein an area ratio of the metal oxide or the metal nitride in the magnetic material is 0.8% to 17.1%.

[0126] <4>

[0127] The magnetic material according to any one of <1> to <3>, wherein the porosity is 0% to 1.5%.

[0128] <5>

[0129] An electronic component includes a base body made of the magnetic material according to any one of <1> to <4>, and wiring.

[0130] <6>

[0131] The electronic component according to <5> is an inductor.

[0132] While one embodiment of the present invention has been described above, this is merely a typical example within the applicable scope of the present invention, and it will be readily understood by those skilled in the art that the present invention is not limited thereto but can be variously modified.

[0133] Industrial applicability

[0134] Electronic components including the magnetic material of the present disclosure may be used as inductors.

[0135] Explanation of symbols

[0136] 100 electronic components

[0137] 60 coating layer

[0138] 50 Second insulation layer

[0139] 30, 40 external electrodes

[0140] 20 Wiring

[0141] 13. First insulation layer

[0142] 11 Sintered body

[0143] 10 green body

[0144] 5 Magnetic Materials

[0145] 3 Sintered body

[0146] 2 Metal oxides or metal nitrides with higher resistivity than sintered bodies

[0147] 1 Metal magnetic body

Claims

1. A magnetic material comprising a metal magnetic body and a sintered body of a metal oxide or metal nitride obtained by oxidation or nitridation of a non-magnetic metal, The metal oxide or the metal nitride is dispersed in the metal magnetic body, The filling rate of the metal magnetic body is 81.4% to 99.2%.

2. The magnetic material according to claim 1, wherein The metal magnetic body contains Fe element, The metal oxide or the metal nitride is an oxide or nitride of at least one metal selected from Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb and Ta, which are elements more easily oxidized than Fe.

3. The magnetic material according to claim 1 or 2, wherein The area ratio of the metal oxide or the metal nitride in the magnetic material is 0.8% to 17.1%.

4. The magnetic material according to any one of claims 1 to 3, wherein The porosity is 0% to 1.5%. 5 . An electronic component comprising a base body comprising the magnetic material according to claim 1 , and wiring. The electronic component according to claim 5 , wherein The electronic component is an inductor.

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