Magnetic material

Abstract

The present disclosure provides a magnetic material that is a sintered article containing a metal magnetic article and a metal oxide or metal nitride obtained by oxidizing or nitriding a non-magnetic metal, wherein the metal oxide or metal nitride is dispersed in the metal magnetic article and the metal magnetic article has a filling rate of 81.4%-99.2% inclusive.

Description

magnetic material

[0001] The present disclosure relates to magnetic materials.

[0002] Composite magnetic materials are sometimes used as magnetic materials for magnetic components, etc. Some composite magnetic materials include a resin containing dispersed soft magnetic powder or the like made of powder particles (see Patent Document 1).

[0003] JP 2016-143827 A

[0004] When a composite magnetic material contains resin, passing a current through a magnetic component comprising a base body containing this magnetic material and wiring can cause localized concentration of magnetic flux between the powder particles of the soft magnetic powder in the magnetic material, which can increase eddy current loss and lead to deterioration of high-frequency characteristics.

[0005] An object of the present disclosure is to provide a magnetic material that can improve high-frequency characteristics.

[0006] In order to achieve the above object, the present disclosure provides a magnetic material that is a sintered body containing a metal magnetic body and a metal oxide or metal nitride in which a non-magnetic metal is oxidized or nitrided, the metal oxide or metal nitride being dispersed in the metal magnetic body, and the filling rate of the metal magnetic body being 81.4% or more and 99.2% or less.

[0007] According to the present disclosure, it is possible to improve high-frequency characteristics.

[0008] Fig. 3 is a photograph of a magnetic material according to the present disclosure. Fig. 4 is a schematic diagram corresponding to Fig. 1. Fig. 5 is a perspective view schematically showing an electronic component according to an embodiment including the magnetic material according to the present disclosure. Fig. 6 is a schematic cross-sectional view taken along line a-a in Fig. 3. Fig. 7 is a perspective view schematically showing an electronic component according to another embodiment.

[0009] Hereinafter, a magnetic material according to an embodiment of the present disclosure will be described with reference to the drawings. Although the description will be made with reference to the drawings as necessary, the contents shown in the drawings are merely shown as schematic examples for understanding the present invention, and the appearance, dimensional ratios, etc. may differ from the actual product.

[0010] Fig. 1 is a photographic diagram showing a magnetic material according to the present disclosure, and Fig. 2 is a schematic diagram corresponding to Fig. 1 .

[0011] The inventors of the present application have conducted extensive research into and devised a new magnetic material with a different structure from conventional magnetic materials, as conventional magnetic materials in which soft magnetic powder is dispersed in resin may lead to deterioration of high-frequency characteristics.

[0012] 1 and 2, 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 in which a non-magnetic metal is oxidized or nitrided. 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% or more and 99.2% or less.

[0013] The metal oxide or metal nitride 2 may have a higher electrical resistivity than the metal magnetic material because it is formed by oxidizing or nitriding a non-magnetic metal. For example, the electrical resistivity of the metal oxide or metal nitride may be 1×10^11 Ω·cm or more and 1×10^16 Ω·cm or less. Furthermore, the electrical resistivity of the metal magnetic material may be 0.089 μΩ·m or more and 1.76 μΩ·m or less. Furthermore, the metal oxide or metal nitride 2 may itself be non-magnetic.

[0014] The metal magnetic body 1 contains elemental Fe. The metal oxide or metal nitride 2 dispersed in the metal magnetic body 1 may be selected from at least one element that is more easily oxidized than Fe: Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb, and Ta. The area ratio of the metal oxide or metal nitride 2 in the magnetic material 5 of the present disclosure may be 0.8% or more and 17.1% or less. The porosity of the magnetic material 5 of the present disclosure may be 0% or more and 1.5% or less.

[0015] Fig. 3 is a perspective view schematically showing an electronic component including the magnetic material of the present disclosure, and Fig. 4 is a schematic cross-sectional view taken along line a-a in Fig. 3.

[0016] 3 and 4 , the electronic component 100 includes an element body 10 including the magnetic material 5 of the present disclosure, wiring 20, and external electrodes 30, 40. By including the magnetic material 5 of the present disclosure, the element body 10 includes a sintered body 11. The sintered body 11 itself has at least one magnetic metal sintered layer. As an example, the element body 10 may have a hexahedral structure. An insulating covering layer 60 may be provided to cover the surface of the element body 10 except for the external electrodes 30, 40.

[0017] In the above-mentioned sintered body 11, when metal magnetic layers of the same composition are stacked consecutively, it is difficult to distinguish the boundaries between the metal magnetic layers. Therefore, even if a sintered body has multiple metal magnetic layers stacked, it is treated as a single sintered body if the first insulating layer described below is not located between them. Also, even if multiple metal magnetic layers of different compositions are stacked and these layers can be distinguished, it is treated as a single sintered body as long as the first insulating layer described below is not located between them.

[0018] As an example, the wiring 20 may be provided within the element body 10. The wiring 20 is made of a conductive material, and may be at least one selected from the group consisting of, for example, silver, copper, aluminum, etc. As an example, the form of the wiring 20 may be straight wiring as shown in FIG. 3 . Without being limited to this, the wiring may also be coil-shaped wiring. The external electrodes 30, 40 are provided on the surface of the element body 10. These external electrodes are connected to both ends of the wiring 20, respectively, and are arranged to face each other at a distance via the element body 10.

[0019] Because the element body 10 contains the magnetic material 5 of the present disclosure, it contains a metal oxide or metal nitride with a relatively high resistance. This makes it possible to increase the electrical resistance of the path of eddy currents flowing through the sintered body 11 of the element body 10, thereby reducing eddy current loss. This eddy current loss increases as the current frequency increases, so reducing eddy current loss makes it possible to improve high-frequency characteristics.

[0020] In the present disclosure, the filling rate of the metal magnetic body 1 in the magnetic material 5 is 81.4% or more and 99.2% or less, and the filling rate of the metal magnetic body 1 in the sintered body 11 of the base body 10 can also be in the same range. Having a filling rate of the metal magnetic body 1 of 81.4% or more makes it possible to preferably ensure magnetic permeability, i.e., inductance value (L value), in the electronic component 100. Furthermore, having a filling rate of the metal magnetic body 1 of 99.2% or less means that the portion of the magnetic material 5 other than the metal magnetic body (0.8% or more), excluding the voids, contains a relatively high-resistivity metal oxide or metal nitride. This allows the above-mentioned eddy current loss to be reduced.

[0021] Furthermore, in the present disclosure, the area ratio of the metal oxide or metal nitride 2 in the magnetic material 5 is 0.8% or more and 17.1% or less, and the area ratio of the metal oxide or metal nitride 2 in the sintered body 11 of the element 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. Also, in the present disclosure, the porosity of the magnetic material 5 is 0% or more and 1.5% or less, and the porosity of the sintered body 11 of the element body 10 can also be within the same range. Therefore, the space factor of the metal magnetic material can be suitably secured in the sintered body 11 as a whole. As a result, a decrease in storable magnetic energy can be suppressed, and the DC bias characteristics are improved.

[0022] 3 and 4, the element body 10 further includes a first insulating layer 13 in addition to the sintered body 11. This first insulating layer 13 can be continuous in a layer form from one side to the other side of the sintered body 11 in a direction intersecting the stacking direction L. In this form, two or more sintered bodies 11 separated by the first insulating layer 13 can be provided.

[0023] In this case, the element body 10 has two or more sintered bodies 11 and a first insulating layer 13, and adjacent sintered bodies 11 and the other sintered body can be stacked with the first insulating layer 13 sandwiched between them. By providing the first insulating layer 13, a magnetic gap function can be provided compared to when the first insulating layer 13 is not provided. Furthermore, the first insulating layer 13 is preferably nonmagnetic. This makes it possible to improve the DC bias characteristics by reducing the magnetic permeability of the element body 10. However, without being limited thereto, the first insulating layer 13 can be a low-permeability insulating layer that is not nonmagnetic but has a magnetic permeability lower than that of the sintered body 11. In this case, inductance can also be improved compared to when it is nonmagnetic.

[0024] The wiring 20 is not limited to the form of the first insulating layer, and may be covered with an insulator. In such a structure, the portions of the wiring 20 other than the ends connected to the external electrodes 30, 40 are directly surrounded by the insulator. This allows the insulator to function as a magnetic gap. It is also preferable that the insulator be non-magnetic.

[0025] This makes it possible to improve the DC bias characteristics by reducing the magnetic permeability of the element body 10. However, without being limited to this, the insulator can be a low-permeability insulator that is not nonmagnetic and has a magnetic permeability lower than that of the sintered body 11. In this case, it is possible to improve the inductance compared to a nonmagnetic case.

[0026] Two or more of the above-mentioned first insulating layers 13 may be provided, spaced apart from each other. In the embodiment shown in FIGS. 3 and 4, the element body 10 has four sintered bodies 11. In this case, the wiring 20 is disposed between the first insulating layers 13, and the element body 10 may include three or more sintered bodies 11. Furthermore, when two or more first insulating layers 13 are provided, a layered structure can be formed in which two or more sintered bodies 11 and first insulating layers 13 are alternately stacked. The arrangement of two or more first insulating layers 13 further provides a magnetic gap function, and if each insulating layer 13 has a lower magnetic permeability than the sintered bodies 11, the DC bias characteristics can be further improved.

[0027] 3 and 4, when the element body 10 has two or more sintered bodies 11, the first external electrode 30 and the second external electrode 40 are arranged on the surfaces of different sintered bodies 11. With such an arrangement of the external electrodes 30, 40, the element body 10 can further have a second insulating layer 50.

[0028] Specifically, the first external electrode 30 and the second external electrode 40 are respectively arranged on the surfaces of adjacent sintered bodies 11, with the first external electrode 30 arranged on the surface of the sintered body 11 on one side and the second external electrode 30 arranged on the surface of the sintered body 11 on the other side. Under this configuration, a second insulating layer 50 can be arranged between one sintered body 11 on which the first external electrode 30 is arranged and the sintered body 11 on which the second external electrode 40 is arranged. By providing such a second insulating layer 50, it is possible to prevent a short circuit between the first external electrode 30 and the second external electrode 40.

[0029] In one example, the second insulating layer 50 may be a slit-shaped tangible object that has an arrangement form extending in a direction intersecting, for example, a direction perpendicular to, the extending direction of the first insulating layer 13. Note that the second insulating layer 50 is not arranged so as to penetrate into and divide the wiring located inside the element body 10.

[0030] In the present disclosure, the wiring does not necessarily have to be arranged inside the element body, and as shown in FIG. 5, the wiring 20A may be arranged in a wound state outside the element body 10A.

[0031] A method for manufacturing an electronic component including the magnetic material of the present disclosure will now be described.

[0032] <Metal Magnetic Particle Preparation Process> First, metal magnetic particles containing an Fe component (e.g., FeNiCo-based particles) are prepared. Next, in one example, a metal alkoxide containing a non-magnetic metal element that is more easily oxidized than Fe is mixed with a solvent (water, alcohol, etc.) by a sol-gel method to produce a slurry, in which the alkoxide is hydrolyzed. The slurry is then dried to obtain metal magnetic particles whose surfaces are covered with a coating film containing an element that is more easily oxidized than Fe. At this time, a second coating film may be formed on the first coating film using a metal alkoxide containing a non-magnetic metal element different from the non-magnetic metal material used in the first coating film. The coating film may be one layer, two layers, or three or more layers.

[0033] Metal alkoxides have 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 the group consisting of Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb, and Ta.

[0034] Although not particularly limited, the metal alkoxide is preferably at least one alkoxide selected from the group consisting of Si, Ti, Al, and Zr. In this specification, Si, which is generally called a semimetal, is treated as a metallic element.

[0035] When the metal alkoxide is at least one alkoxide selected from the group consisting of Si, Ti, Al and Zr, a metal oxide having higher strength and higher resistivity can be formed.

[0036] 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, and more particularly 3 or less. The smaller the carbon number, the more easily the hydrolysis reaction can proceed. The alkoxy group is preferably at least one selected from the group consisting of a methoxy group, an ethoxy group, and a propoxy group.

[0037] Specifically, the metal alkoxide is preferably at least one selected from the group consisting of tetraethyl orthosilicate, titanium tetraisopropoxide, zirconium n-butoxide, and aluminum isopropoxide.

[0038] The slurry may contain a water-soluble polymer, which may be at least one selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, hydroxypropyl cellulose, poly(2-methyl-2-oxazoline), polyethyleneimine, polyacrylic acid, and carboxymethyl cellulose.

[0039] It should be noted that the method is not limited to the sol-gel method described above, and a coating film containing an element that is more easily oxidized than Fe may be formed on the surface of the metal magnetic particles. Furthermore, the metal magnetic particles themselves may further contain an element that is more easily oxidized than Fe as a composition. Furthermore, a metal nitride component may be applied to the surface of the metal magnetic particles. Naturally, metal oxides and metal nitrides of non-magnetic metals are non-magnetic.

[0040] <Metallic Magnetic Substance Paste Preparation Step> After preparing the metallic magnetic particles, the metallic magnetic particles, varnish, solvent (e.g., terpineol), etc. are mixed in a stirrer, and then dispersed in a roll mill to obtain a metallic magnetic substance paste.

[0041] <Insulator Paste Preparation Step> Non-magnetic insulator particles are prepared. Then, the insulator particles, varnish, and a solvent (e.g., terpineol) are mixed in a mixer. A dispersion process is then performed in a roll mill to obtain an insulator paste. The non-magnetic insulator used in the insulator paste may be, for example, a mixture of alumina, silica, glass, or a dielectric material such as calcium zirconate, strontium zirconate, and / or barium zirconate with borosilicate glass or the like.

[0042] <Process for preparing wiring paste> Conductive particles, varnish, a solvent (e.g., terpineol), etc. are mixed in a mixer. Then, a dispersion process is performed in a roll mill to obtain a wiring paste. The conductive particles can be selected from copper particles, silver particles, etc.

[0043] <Preparation process of unfired laminate> After preparing each paste, the above-mentioned metal magnetic paste is used to form a metal magnetic layer of a predetermined thickness by, for example, screen printing, and then dried. After drying, slit grooves of a predetermined width are formed by laser processing, and the above-mentioned insulating paste is filled into these slit grooves by screen printing or the like, and then dried. Note that the slit grooves are not limited to post-processing by laser processing, and may also be patterned in advance using a screen printing plate or the like.

[0044] After filling the slit grooves with an insulating paste and drying it, an insulating layer of a predetermined thickness is formed on the metal magnetic layer using the insulating paste by screen printing, and then dried. The insulating paste used to form the insulating layer may be of a different type from the insulating paste filled in the slit grooves.

[0045] On top of that, wiring of the desired shape (for example, straight shape, coil shape, meander shape, etc.) is formed by screen printing using a wiring paste. When forming coil-shaped wiring, via patterns that connect wiring patterns to each other are formed in multiple metal magnetic layers using the wiring paste. The via pattern can be formed by first forming holes in the metal magnetic layer by laser processing or the like and filling them with wiring paste. After forming the wiring, an insulating layer may be further formed thereon. The formation of the above metal magnetic layer and, optionally, the formation of an insulating layer are repeated to obtain an unsintered laminate.

[0046] If the L value of the resulting electronic component is higher than the desired characteristic, the number of insulating layers may be reduced or eliminated. This makes it possible to adjust the balance between the L value and the DC bias characteristic. Furthermore, while the above embodiment shows a case in which screen-printed layers formed using a screen printing method are laminated, the present invention is not limited to this, and the electronic component may also be produced by laminating separately prepared sheets.

[0047] <Single-piece and Firing Process of Unfired Laminate> The unfired laminate is cut into pieces using a dicer or the like, and the pieces are then degreased in a firing furnace in a nitrogen atmosphere. ２ :3% / N ２ : Firing is performed in a 97% reducing atmosphere at a temperature of 900°C to 1000°C for a predetermined time (e.g., 1 hour). This allows for the production of a sintered laminate containing the magnetic material of the present disclosure and an insulating layer. The sintered laminate obtained may contain oxides or nitrides of elements that are more easily oxidized than Fe. Note that elements that are more difficult to oxidize than Fe may be oxidized in a separate process and then included in the sintered laminate.

[0048] Furthermore, although the above is based on the premise that a non-magnetic insulating layer is formed, it is also possible to obtain an insulating layer with low magnetic permeability and some magnetic properties by, for example, extending the holding time at the maximum temperature during the firing step, thereby diffusing and penetrating the metal magnetic material components from the metal magnetic material layer into the non-magnetic insulating layer.

[0049] <Formation of External Electrodes> The outer surface of the sintered body is then coated with an insulating resin or the like, and the coating is removed from the areas where the wiring and external electrodes are connected using a laser or the like. Then, a plating process is performed to form external electrodes, and finally, an electronic component is obtained. The material for the external electrodes can be, for example, silver.

[0050] Hereinafter, examples of the present disclosure will be described.

[0051] <Acquisition of B-H Data (for Simulation)> First, metal magnetic particles, varnish (resin type: ethyl cellulose, product name: Ethocel), and terpineol as a solvent were mixed in a mortar, and the resulting paste was oven-dried to remove the solvent, and the dried product was passed through a mesh to produce granulated powder. The granulated powder was press-molded at 120 MPa for 2 minutes while heated to 80°C, to produce a toroidal core and a cylindrical sample, respectively. After that, the powder was degreased in a nitrogen atmosphere and then molten under H ２ :3% / N ２ The mixture was fired at 900°C for 60 minutes in a 97% reducing atmosphere to obtain a toroidal core and a cylindrical sample made of a magnetic metal sintered body.

[0052] 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.) to measure the saturation magnetic flux density Bs (16,000 Oe). The measured μ and Bs were substituted into the following equation to calculate the B-H data: B = Bs × tanh(4π × 10 －７ ×μ×H / Bs)

[0053] To calculate Bs, the density of the metal material itself (Fe: 7.87 g / cm 3 , Ni: 8.9g / cm ３ , Co: 8.9g / cm ３ The alloy densities calculated from the composition ratio of each alloy were as follows: Fe10Ni20Co: 8.16 g / cm ３

[0054] <Acquisition of Electrical Conductivity (for Simulation)> After mixing metal magnetic particles, varnish (resin type: ethyl cellulose, product name: Ethocel), and terpineol as a solvent in a mortar, the paste was printed on an alumina substrate using a metal mask with dimensions of 30 mm x 5 mm x 0.2 mm. The printed material was degreased in a nitrogen atmosphere and then immersed in H ２ :3% / N ２ The sample was baked at 900°C for 60 minutes in a 97% reducing atmosphere, and the electrical resistance was measured using the four-terminal method to calculate the conductivity.

[0055] <Calculation of Metal Magnetic Material Filling Rate, Void Fraction, and High-Resistance Area Fraction (for Simulation)> Each sintered sample was resin-solidified, polished with a Tegramin-25 polishing machine (manufactured by Struers), and subjected to ion milling with an IM-3000 ion milling machine (manufactured by Hitachi High-Technologies Corporation). SEM images and element mapping images were then acquired using a field-emission scanning electron microscope SU8230 (manufactured by Hitachi High-Technologies Corporation). The imaging magnification was 2000x. These acquired images were analyzed using image analysis software WinROOF2021 (manufactured by Mitani Shoji Co., Ltd.), and the respective area fractions were calculated.

[0056] The average value of analytical values ​​at three arbitrary locations about halfway along the thickness direction of the sintered toroidal core was used. When calculating for the final electronic component, the average value was taken from analytical values ​​at six locations in total: three arbitrary locations located above the top surface of the internal wiring at a distance equal to the wiring thickness, and three arbitrary locations located below the bottom surface of the internal wiring at a distance equal to the wiring thickness. The method for visualizing high resistance portions will be described later.

[0057] <Simulation Conditions and Model> In the simulation, Femtet (registered trademark) from Murata Software Co., Ltd. was used. The software used was Femtet2022. The solver was set to magnetic field analysis (harmonic analysis), and the option was set to "Calculate inductance." The model was three-dimensional. The standard mesh size was set to 0.03 mm.

[0058] The B-H curve of the magnetic material was calculated using the values ​​calculated above. Note that the B-H curve used the portion where the relative permeability μr was 1 or more so that it would not become less than the permeability of a vacuum, and was then extrapolated to the permeability of a vacuum using the functions of Femtet2022. The conductivity of the magnetic material was calculated using the values ​​calculated above, and the iron loss was "only Joule loss (calculated from the current distribution)." The wiring material was silver.

[0059] The electronic component model consisted of a silver straight wiring (length: width: thickness: 1.0 mm: 0.0625 mm: 0.02 mm) formed inside an element body with a length (L): width (W): height (T) of 1.0 mm: 0.5 mm: 0.629 mm, 0.315 mm from the bottom surface at the center of the width. Nonmagnetic insulating layers (length (L): width (W): height (T) of 1.0 mm: 0.5 mm: 0.002 mm) were formed on the top and bottom surfaces of the straight wiring. Furthermore, a nonmagnetic insulating layer (width: 0.01 mm) was formed at the center of the length (L) between the two external electrodes, separating the sintered body into two.

[0060] Although we used simulation this time, electronic components can be manufactured through the following process.

[0061] Related to Examples 1 to 12 and Comparative Example 1 <Metal Magnetic Particle Preparation Process> First, Fe10Ni20Co particles with a D50 particle size of 0.40 μm were prepared. Next, a sol-gel method was used to mix Si alkoxide and a solvent (water) to prepare a slurry, and the alkoxide was hydrolyzed in this slurry. The slurry was then dried to obtain metal magnetic particles whose surfaces were covered with a sol-gel coating film containing Si. The amount of this Si alkoxide was adjusted to appropriately set the target film thickness described below. There are no particular restrictions on the D50 particle size, but it may be 0.40 μm or more and 3.10 μm or less.

[0062] <Preparation of Metallic Magnetic Substance Paste> After preparing the metallic magnetic substance particles, the metallic magnetic substance particles, the varnish, and terpineol as a solvent were mixed in a stirrer, followed by a dispersion treatment in a roll mill to obtain a metallic magnetic substance paste.

[0063] <Insulator Paste Preparation Process> Non-magnetic insulating particles of alumina 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 were then mixed with varnish and terpineol as a solvent using a stirrer. The mixture was then dispersed using a roll mill to obtain an insulator paste.

[0064] <Process for preparing wiring paste> Silver particles with a D50 particle size of about 1 to 5 μm, varnish, and terpineol as a solvent were mixed in a stirrer, and then dispersed in a roll mill to obtain a wiring paste.

[0065] <Preparation of Unfired Laminate> After preparing each paste, the above-mentioned metal magnetic paste was used to form a metal magnetic layer of a predetermined thickness by screen printing, followed by drying. After drying, slit grooves of a predetermined width were formed by laser processing, and the above-mentioned insulating paste was filled into the slit grooves by screen printing or the like, followed by drying.

[0066] The slit grooves were filled with an insulating paste and dried, and then an insulating layer of a predetermined thickness was formed thereon using the above insulating paste by screen printing, and then dried.

[0067] Wiring paste was used to form wiring of a desired shape on the laminate by screen printing. By forming the metal magnetic material layer and the insulating layer as described above, an unfired laminate was obtained.

[0068] <Single-piece and Firing Process of Unfired Laminate> The unfired laminate is cut into pieces using a dicer or the like, and the pieces are then degreased in a firing furnace in a nitrogen atmosphere. ２ :3% / N ２ The mixture was fired at 900° C. for 1 hour in a 97% reducing atmosphere. This resulted in a sintered body having a high resistance portion inside and a fired laminate of insulating layers.

[0069] <Formation of External Electrodes> The outer surface of the sintered body was then coated with an insulating resin, and the coating was removed from the areas where the wiring and external electrodes were to be connected using a laser. Then, a plating process was performed to form external electrodes. The material for the external electrodes may be, for example, silver. This completes the process to obtain an electronic component.

[0070] Table 1 shows the results of measurements taken for each item, rather than a simulation, in which a sintered material was actually produced by firing the metal magnetic paste as described in the "Metal Magnetic Paste Preparation Process" and "Unfired Laminate Slicing and Firing Process" sections. No wiring or insulating layers were provided, and only the sintered material was produced. Table 2 shows the results of a simulation using the actual measurement data in Table 1.

[0071] The evaluation criteria were set as follows: inductance (L) at 100 Hz is 9 nH or more, and ΔL (the rate of change of inductance (L) at 100 kHz relative to inductance (L) at 100 Hz) is -7% or more. Products that met both criteria were given an overall evaluation of ◯ (suitable).

[0072] [Table 1] Measurement results 1

[0073] [Table 2] Measurement results 2

[0074] In the electronic component obtained as described above, the sintered body (magnetic material) which is a constituent element of the element body contains a metal magnetic body and silicon oxide dispersed in the metal magnetic body, and the filling rate of the metal magnetic body in the sintered body is 81.4% or more and 99.2% or less. ２ As a result, the Joule loss, i.e., the eddy current loss, of the obtained magnetic metal sintered body was large, which resulted in a ΔL of -7.8%, resulting in an overall rating of ×.

[0075] In contrast, in Examples 1 to 12, compared to Comparative Example 1, Si oxides in the high-resistivity portions dispersed in the metal magnetic material were present; specifically, the area ratio of the high-resistivity portions was 0.8% or more and 17.1% or less. Therefore, the electrical conductivity was reduced, and the Joule loss of the resulting metal magnetic sintered body was accordingly reduced. As a result, ΔL was -7% or more in all of Examples 1 to 12. Furthermore, the metal magnetic material was filled in the metal magnetic sintered body within a predetermined range, specifically, the filling rate was 81.4% or more and 99.2% or less, ensuring a magnetic permeability above a predetermined value (25 or more). As a result, an inductance (L) of 9 nH or more at 100 Hz was ensured. For these reasons, the overall evaluation was ◯ for all of Examples 1 to 12.

[0076] The following method can be used to visualize the high-resistance portions: Specifically, each fired sample was hardened with resin, polished with a Tegramin-25 polishing machine (manufactured by Struers), and then processed by FIB (focused ion beam) processing into a shape suitable for subsequent SPM (scanning probe microscope) measurement, and finally cleaned by Ar flat milling.

[0077] Using such processed samples, spreading resistance was measured using the SPM's SSRM (Scanning Spreading Resistance Microscopy) mode, in which a conductive probe is scanned across the sample while applying a bias voltage, and the current flowing at each point is converted into a resistance value, thereby visualizing high-resistance regions.

[0078] In this study, the high resistance portion was defined as the portion having a resistance value 10^3 times or more of the maximum measured resistance value of the metal magnetic material. However, the threshold value can be adjusted appropriately by referring to the element mapping image so as to match the position of high resistance materials such as oxides and nitrides.

[0079] FIG. 1 shows the SiO2 high resistance portion of the sintered body produced in this example. ２ This is an image taken at a magnification of 2000 times, visualizing the above. The colored areas are element mapping using Si elements. The remaining areas are metal magnetic material or voids. In this case, the grain boundary phase of the metal magnetic material particles could not be confirmed even with a microscope.

[0080] This is because the grain growth of the metal magnetic particles that are the material of the metal magnetic body occurs, and the adjacent metal magnetic particles are bonded to each other. ２ As a result, the SiO that was coated on the metal magnetic particles during the manufacturing process was pushed aside. ２ It is believed that the high-resistivity grains do not remain in the grain boundary phase of the metal magnetic particles, but rather gather and solidify after sintering at positions that were in contact with three or more metal magnetic particles before compounding. In this way, the high-resistivity grains are dispersed throughout the sintered body, which suppresses eddy current loss in the sintered body. Therefore, it was found that a sintered body with high magnetic permeability can be produced, even at high frequencies.

[0081] The present invention includes the following embodiments, but is not limited to these. <1> A magnetic material that is a sintered body containing a metal magnetic body and a metal oxide or metal nitride formed by oxidizing or nitriding a non-magnetic metal, the metal oxide or metal nitride being dispersed in the metal magnetic body, and the filling factor of the metal magnetic body being 81.4% to 99.2%. <2> The magnetic material according to <1>, wherein the metal magnetic body contains Fe element, and the metal oxide or metal nitride is an oxide or nitride of at least one metal selected from the group consisting of Si, Al, Cr, Ca, Mg, Ti, Mn, V, Zr, Nb, and Ta, which are elements that are more easily oxidized than Fe. <3> The magnetic material according to <1> or <2>, wherein the area ratio of the metal oxide or metal nitride in the magnetic material is 0.8% to 17.1%. <4> The magnetic material according to any one of <1> to <3>, wherein the porosity is 0% to 1.5%. <5> An electronic component comprising an element body including the magnetic material according to any one of <1> to <4> and wiring. <6> The electronic component according to <5>, which is an inductor.

[0082] Although one embodiment of the present invention has been described above, it is merely a typical example within the scope of application of the present invention. Therefore, it will be readily understood by those skilled in the art that the present invention is not limited to this embodiment and that various modifications can be made.

[0083] An electronic component including the magnetic material of the present disclosure can be used as an inductor.

[0084] REFERENCE SIGNS LIST 100 Electronic component 60 Covering layer 50 Second insulating layer 30, 40 External electrode 20 Wiring 13 First insulating layer 11 Sintered body 10 Base body 5 Magnetic material 3 Sintered body 2 Metal oxide or metal nitride having higher electrical resistivity than the sintered body 1 Metal magnetic body

Claims

1. A sintered body containing a metal magnetic material and a metal oxide or metal nitride in which a non-magnetic metal is oxidized or nitrided, the metal oxide or the metal nitride is dispersed in the metal magnetic material, A magnetic material in which the filling rate of the metal magnetic material is 81.4% or more and 99.2% or less.

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

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

4. 2. The magnetic material according to claim 1, wherein the porosity is 0% or more and 1.5% or less.

5. An electronic component comprising an element body containing the magnetic material according to any one of claims 1 to 4 and wiring.

6. The electronic component according to claim 5 , which is an inductor.