Method for manufacturing a magnetic body and coil component comprising a magnetic body

Abstract

The technical problem of the present invention is to obtain a coil component having excellent direct current superimposition characteristics and magnetic permeability, wherein, in a magnetic body made of a Ni-Zn ferrite material, no additive other than the main component in the Ni-Zn ferrite material is contained as a necessary component. In manufacturing a magnetic body having a Ni-Zn ferrite as a main component, an iron oxide powder having a Mn content of 0.20 to 0.85 mass% is used as a raw material powder, or an iron oxide powder having a Mn content of 0.20 mass% or more is used as a raw material powder, and a molar ratio (Ni / Zn) of Ni to Zn in the ferrite material is determined based on the Mn content in the iron oxide powder, and the raw material powder is adjusted to obtain the molar ratio.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a magnetic material and a coil component comprising a magnetic material. Background Technology

[0002] Coil components, such as inductors that combine magnetic materials and windings, are sometimes used to convert voltage in power supply circuits. In this case, a direct current of about 1 to 10 A flows through the coil component. Therefore, it is required that the inductive characteristics of the current in the coil component change little, that is, that is, excellent DC superposition characteristics. As a method to obtain coil components with excellent DC superposition characteristics, one example is to use a component with high saturation magnetic flux density as the magnetic material. To obtain such a magnetic material, research has been conducted on materials.

[0003] Among magnetic materials used in coil components, Mn-Zn ferrites are excellent for forming coil components with superior DC superposition characteristics due to their high saturation magnetic flux density and low loss. However, because of their low resistivity and insufficiently high resistance relative to the applied voltage, they require winding through an insulator when used as coil components. Therefore, the increase in coil component volume is equivalent to the amount of insulator, making it difficult to obtain small-sized coil components.

[0004] On the other hand, Ni-Zn ferrites are advantageous in terms of miniaturization because of their excellent insulation properties, allowing them to be directly wound on magnetic materials. However, compared to Mn-Zn ferrites, they tend to have lower saturation flux density and poorer DC superposition characteristics. Therefore, various studies have been conducted to improve these aspects.

[0005] For example, in Patent Document 1, the composition of Ni-Zn ferrite is set to include a specific composition containing manganese oxide (Mn2O3). Patent Document 1 states: "Compared with conventional NiCuZn ferrite, by replacing the Fe2O3 sites of NiCuZn ferrite with Mn2O3, an oxide magnetic material with high saturation magnetic flux density, low loss and very high resistivity can be obtained" (paragraph

[0048] ).

[0006] Furthermore, in Patent Document 2, in order to further improve the DC superposition characteristics compared to Patent Document 1, calcium silicate (CaSiO3) and antimony oxide (Sb2O3) are added as secondary components to the pre-calcined powder whose main component composition is adjusted to a specific range by adding manganese oxide (MnO), thereby obtaining Ni-Zn ferrite. Patent Document 2 states as follows: "This Ni-Zn ferrite material has added manganese (Mn), thereby resulting in a large saturation magnetic flux density and good DC superposition characteristics." (Paragraph

[0050] ).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2002-289421

[0010] Patent Document 2: Japanese Patent Application Publication No. 2017-197417 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] However, as disclosed or implied in Patent Documents 1 and 2 (both paragraph

[0050] ), the inclusion of Mn in Ni-Zn ferrites may lead to a decrease in magnetic permeability.

[0013] In Patent Document 2, by adding a secondary component, an increase in the relative permeability and saturation flux density of the magnetic material, as well as a decrease in core loss, were confirmed. Therefore, it can be said that the method described in Patent Document 2 improves the DC superposition characteristics of the coil component and suppresses the decrease in permeability caused by Mn. However, this method has the following problems: because a harmful substance, namely Sb2O3, is used as an additive, it needs to be strictly managed; and because the amount of the secondary component is very small relative to the main component, it is difficult to disperse it uniformly.

[0014] The present invention was made in view of the above-mentioned problems, and its object is to obtain a coil component with excellent DC superposition characteristics and magnetic permeability characteristics, wherein the magnetic body made of Ni-Zn ferrite material does not contain any additives other than the main component of the Ni-Zn ferrite material as essential components.

[0015] Solutions for solving technical problems

[0016] In their research aimed at achieving the aforementioned objectives, the inventors of this invention discovered that even when raw materials are formulated to obtain Ni-Zn ferrite materials of the same composition, the characteristics of the resulting magnetic material and the coil components obtained using that magnetic material differ depending on the type of raw materials used. Specifically, they found that in the manufacture of magnetic materials made from Ni-Zn ferrite materials, existing methods that add Mn as a trace additive relative to the main raw material cannot completely eliminate the influence of poor dispersion, inevitably causing adverse effects on the characteristics of the coil components. Furthermore, they discovered that by using iron oxide powder containing a specific amount of Mn as the raw material for manufacturing the magnetic material instead of additives such as manganese oxide, and by formulating the raw material powder as needed to achieve a suitable molar ratio (Ni / Zn) of Ni and Zn in the iron oxide powder with appropriate Mn content, the aforementioned technical problems can be solved, thus completing this invention.

[0017] That is, one embodiment of the present invention for solving the above-mentioned technical problems is a method for manufacturing a magnetic body made of a ferrite material containing Fe, Ni and Zn. The method is characterized in that iron oxide powder with a Mn content of 0.20% to 0.85% by mass is used as the raw material powder.

[0018] Another embodiment of the present invention for solving the above-mentioned technical problems is a method for manufacturing a magnetic body made of a ferrite material containing Fe, Ni and Zn. The method is characterized in that iron oxide powder with a Mn content of 0.2% by mass or more is used as the raw material powder, and the molar ratio of Ni to Zn in the ferrite material (Ni / Zn) is determined based on the Mn content in the iron oxide powder, and the raw material powder is prepared to obtain the molar ratio.

[0019] The effects of the invention

[0020] According to the present invention, a coil component with excellent DC superposition characteristics and magnetic permeability characteristics can be provided, wherein the magnetic body made of a ferrite material containing Fe, Ni and Zn does not contain any additives other than the main components of the ferrite material. Attached Figure Description

[0021] Figure 1 This is a graph showing the relationship between the Mn content and relative permeability of the coil components in the embodiments and comparative examples of the first embodiment of the present invention (black circle: no additional Mn added, white circle: additional Mn added).

[0022] Figure 2 This is a graph showing the relationship between the Mn content and DC superposition characteristics of the coil components in the embodiments and comparative examples of the first embodiment of the present invention (black circle: no additional Mn added, white circle: additional Mn added).

[0023] Figure 3 This is a graph showing the relationship between the Mn content and the temperature dependence of the inductance of the coil component in the embodiments and comparative examples of the first embodiment of the present invention (black circle: no additional Mn added, white circle: additional Mn added). Detailed Implementation

[0024] The present invention and its effects will now be described with reference to the accompanying drawings and in conjunction with the technical concept. However, the mechanism of action includes conjecture, and its correctness does not limit the present invention. Furthermore, in the constituent elements of the following embodiments, constituent elements not described in the independent claims representing the highest concept will be described as arbitrary constituent elements. In addition, the description of numerical ranges (a description connecting two numerical values ​​with "~") also includes numerical values ​​described as lower and upper limits.

[0025] In one embodiment of the present invention, the ferrite material comprising Fe, Ni, and Zn constituting the magnetic body is also referred to as a Ni-Zn ferrite material. This ferrite material contains Fe, Ni, and Zn as main components, and in most cases, it also contains Cu. Depending on the circumstances, it may also contain trace amounts of additives or impurities. A method for manufacturing a magnetic body made from the above-mentioned ferrite material according to one embodiment of the present invention (hereinafter, sometimes simply referred to as "First Embodiment") includes: a step of preparing raw material powder; a step of mixing the above-mentioned raw material powder to prepare a mixed powder; a step of heat-treating the above-mentioned mixed powder to prepare a pre-calcined powder with Fe, Ni, and Zn as the main components; a step of molding the above-mentioned pre-calcined powder to form a molded body; and a step of firing the above-mentioned molded body to form a magnetic body. The First Embodiment is characterized in that, as the above-mentioned raw material powder, iron oxide powder with a Mn content of 0.20% to 0.85% by mass is used.

[0026] In the first embodiment, the iron oxide powder used as a raw material contains 0.20% to 0.85% Mn by mass. By setting the Mn content in the iron oxide to 0.20% or more by mass, the coil component made of the resulting magnetic material can be a component with excellent DC superposition characteristics. From the viewpoint of obtaining a coil component with relatively excellent DC superposition characteristics, it is preferable to set the Mn content in the iron oxide powder to 0.30% or more by mass. On the other hand, by setting the Mn content in the iron oxide powder to 0.85% or less by mass, a magnetic material with excellent permeability can be obtained. From the viewpoint of obtaining a magnetic material with even better permeability, it is preferable to set the Mn content to 0.80% or less by mass. In addition, by setting the Mn content in the aforementioned iron oxide powder to 0.80% or less by mass, a coil component with even better DC superposition characteristics can also be obtained.

[0027] The Mn content in the iron oxide powder of the first embodiment refers to the value obtained by analyzing the obtained iron oxide powder using ICP emission spectroscopy. Alternatively, if the obtained iron oxide powder is accompanied by an analysis table based on ICP emission spectroscopy or an analysis method of equivalent or higher precision, the value shown in that analysis table can be directly used as the Mn content.

[0028] In the first embodiment, the raw material powder used, excluding iron oxide, is not particularly limited as long as it contains the essential components of a magnetic material, namely nickel (Ni) and zinc (Zn). Various compounds, such as elemental metals, alloys, or oxides, can be used. The compound can be a compound containing multiple metallic elements, such as a composite oxide. Among these, NiO and ZnO as oxides are preferred because they exhibit small deviations in particle shape and size, making it easy to obtain powders composed of small-diameter particles.

[0029] The proportions of the aforementioned raw material powders are not particularly limited as long as a Ni-Zn ferrite material can be obtained. For example, the raw material powders can be formulated such that the contents of Fe, Zn, and Ni in the Ni-Zn ferrite material, calculated as Fe2O3, ZnO, and NiO, are 47.3–49.8 mol% Fe2O3, 15.0–36.9 mol% ZnO, and 15.0–36.9 mol% NiO. As an example of raw material powder formulation expressed in mass percent, the contents of the aforementioned components in the Ni-Zn ferrite material can be formulated such that, calculated as Fe2O3, ZnO, and NiO, the contents are 64.4–67.4 wt% Fe2O3, 10.4–25.6 wt% ZnO, and 9.4–23.8 wt% NiO. The proportions of the raw material powders are determined to account for the reduction of various components due to volatilization and other factors during the manufacturing process, in order to obtain a Ni-Zn ferrite material with the desired composition. If the components are almost not reduced during manufacturing, the proportions can be set to be the same as the composition of the desired Ni-Zn ferrite material. Furthermore, generally speaking, the composition of the formulated powder and the resulting Ni-Zn ferrite material are almost identical.

[0030] In the first embodiment, one of the raw material powders preferably contains copper (Cu). Since the Ni-Zn ferrite material contains Cu, its sinterability during firing is improved, resulting in a magnetic material with excellent magnetic properties and mechanical strength. Regarding the Cu content in the raw material powder, to fully utilize the aforementioned improvement in sinterability, it is more preferable to adjust the Cu content in the Ni-Zn ferrite material, calculated as CuO, to be 1 mol% or more, and more preferably to 3 mol% or more. On the other hand, regarding suppressing deformation of the molded or sintered body during firing, regarding the Cu content in the raw material powder, it is more preferable to adjust the Cu content in the Ni-Zn ferrite material, calculated as CuO, to be 13 mol% or less, and more preferably to 11 mol% or less. Examples of raw material powder formulation for Ni-Zn ferrite materials containing Cu include the following: The raw material powders are formulated such that the contents of Fe, Zn, Ni, and Cu in the Ni-Zn ferrite material, converted from Fe2O3, ZnO, NiO, and CuO, are 41.6–49.3 mol% Fe2O3, 13.3–36.5 mol% ZnO, 13.3–36.5 mol% NiO, and 1.0–12.1 mol% CuO. Examples of raw material powder formulation, expressed as mass%, include the following: The contents of the above components in the Ni-Zn ferrite material, converted from Fe2O3, ZnO, NiO, and CuO, are formulated such that the contents are 58.9–66.9 wt% Fe2O3, 9.5–25.4 wt% ZnO, 8.6–23.6 wt% NiO, and 0.6–8.6 wt% CuO. The Cu content (converted to CuO) is preferably 2% by mass or more, and more preferably 8% by mass or less.

[0031] The raw material powder containing Cu is not particularly limited, and various compounds, such as metallic copper, copper alloys, or oxides, can be used. The compound can be a compound containing metallic elements other than Cu, such as a composite oxide. Among these, CuO as an oxide is preferred because it has small deviations in particle shape and size, and can easily produce powder composed of small-diameter particles.

[0032] In the first embodiment, unavoidable impurities of up to several hundred ppm are permitted in the raw material powder or even the magnetic material.

[0033] Examples of unavoidable impurities include typical metallic elements such as B, C, S, Cl, Se, Br, Te, I, or Li, Na, Mg, Al, K, Ga, Ge, Sr, In, Sn, Sb, Ba, Pb, and Bi, as well as transition elements such as Sc, Ti, V, Cr, Y, Nb, Mo, Pd, Ag, Cd, Hf, and Ta.

[0034] Even without using the additives other than the main component, the first embodiment can provide a coil component with excellent DC superposition characteristics. However, in order to obtain a coil component with higher performance, various secondary components can be added to the Ni-Zn ferrite material to manufacture a magnetic body.

[0035] In the first embodiment, the mixing method of the raw material powder is not particularly limited as long as impurities are prevented from being mixed in and the powders are mixed evenly; either dry mixing or wet mixing can be used. When using wet mixing with a ball mill, the mixing time is, for example, approximately 8 to 24 hours.

[0036] The heat treatment conditions for the mixed powder are not limited as long as the raw materials react to obtain the pre-calcined Ni-Zn ferrite powder (Ni-Zn ferrite material) with the desired composition. For example, the following conditions are acceptable: in an atmospheric atmosphere, at 800℃~1000℃ for 1 hour to 3 hours. If the firing temperature is too low or the firing time is too short, unreacted raw materials or intermediate products may remain. Conversely, if the firing temperature is too high or the firing time is too long, the desired composition of the compound may not be obtained due to component volatilization, or the productivity may be reduced due to the product solidification being difficult to break.

[0037] In the first embodiment, if the pre-fired powder obtained by the above heat treatment agglomerates, it is preferable to crush it before molding. Crushing is performed to break up the agglomeration of the pre-fired powder and produce a powder with appropriate sintering properties. Crushing can be carried out dry using a vibratory mill, hammer mill, roller mill, etc., but if the pre-fired powder forms large lumps, it is preferable to perform wet crushing using a ball mill or ultrafine mill after coarse crushing. In terms of formability, shape retention, and sintering properties, it is preferable to crush until the average particle size of the pre-fired powder is about 0.5 μm to 2 μm.

[0038] In the first embodiment, the pre-calcined powder may also be granulated before molding to obtain granules. Granulation is performed to make the pulverized material into aggregated particles of appropriate size, in a form suitable for molding. Examples of such granulation methods include pressure granulation or spray drying.

[0039] In the first embodiment, the pre-fired powder obtained therefrom is molded into a predetermined shape to obtain a molded body. The molding method is not particularly limited; examples include uniaxial pressure molding of the powder, extrusion molding of a clay containing the powder, and casting molding of a slurry containing dispersed powder. The shape of the molded body is also not particularly limited; it can be appropriately selected from known shapes such as rods, plates, rings, and drums, depending on the application.

[0040] In the first embodiment, the resulting molded body is fired to produce a magnetic body. This causes the powder particles contained in the molded body to sinter together, forming a dense sintered body. The firing conditions are not limited as long as a dense magnetic body can be obtained; for example, conditions such as firing at 900–1200°C in an atmospheric atmosphere for approximately 1–5 hours are acceptable. If the firing temperature is too low or the firing time is too short, insufficient densification may result in a magnetic body with the desired properties not being obtained. Conversely, if the firing temperature is too high or the firing time is too long, compositional deviations may occur due to component volatilization, or the properties may decrease due to the formation of coarse particles. Furthermore, firing can also be carried out in an atmosphere with an oxygen partial pressure higher than atmospheric pressure.

[0041] Another embodiment of the present invention, a method for manufacturing a magnetic body made of the above-described ferrite material (hereinafter sometimes simply referred to as "the second embodiment"), differs from the first embodiment in only the following two aspects. First, the Mn content in the iron oxide powder used as the raw material powder is 0.20% by mass or more, without limitation on its upper limit. Second, the molar ratio (Ni / Zn) of Ni in the ferrite material is determined based on the Mn content in the iron oxide powder, and the raw material powder is prepared to obtain this molar ratio. The above two points will now be described in detail.

[0042] In the second embodiment, the iron oxide powder used as a raw material contains 0.20% by mass or more of Mn. Similar to the first embodiment, by setting the Mn content in the iron oxide to 0.20% by mass or more, the coil component made of the resulting magnetic material can be made into a component with excellent DC superposition characteristics. From the viewpoint of obtaining a coil component with even better DC superposition characteristics, it is preferable to set the Mn content in the iron oxide powder to 0.30% by mass or more. In the second embodiment, the upper limit of the Mn content in the iron oxide powder is not particularly limited. This is because by adjusting the molar ratio of Ni to Zn (Ni / Zn), which will be described later, the decrease in permeability accompanying the increase in the Mn content can be compensated. From the viewpoint of obtaining a magnetic material with excellent permeability, it is preferable to set the Mn content to 0.85% by mass or less, more preferably to 0.80% by mass or less. Furthermore, by setting the Mn content in the iron oxide powder to 0.80% by mass or less, a coil component with even better DC superposition characteristics can also be obtained.

[0043] In the second embodiment, the molar ratio (Ni / Zn) of Ni to Zn in the Ni-Zn ferrite material is determined based on the Mn content in the iron oxide powder used as a raw material, and the raw material powder is prepared to obtain this molar ratio. Specifically, the higher the Mn content in the iron oxide powder, the smaller the molar ratio (Ni / Zn). This was determined by the inventors based on the following recently known fact: when the Mn content in the iron oxide powder used as a raw material is high, the final coil component exhibits particularly excellent DC superposition characteristics, but the permeability is slightly reduced. In Ni-Zn ferrite materials, by reducing the Ni / Zn molar ratio, although the DC superposition characteristics are slightly reduced, the permeability can be increased, thereby compensating for the slight reduction in permeability. In fact, when determining the Ni / Zn molar ratio of the Ni-Zn ferrite material, the following steps can be repeatedly performed: a magnetic body composed of a Ni-Zn ferrite material with a specific composition is prepared and its characteristics are measured, and the composition is changed based on the measurement results. Alternatively, the Ni / Zn molar ratio can be determined through simulation based on a database of pre-determined and collected composition and properties.

[0044] As mentioned above, reducing the Ni / Zn molar ratio leads to a reduction in the amount of Ni-containing raw materials used in the raw material powder for manufacturing Ni-Zn ferrite materials. Ni-containing raw materials, represented by NiO, are the most expensive raw materials used in the raw material powder for manufacturing Ni-Zn ferrite materials. Therefore, by reducing the Ni / Zn molar ratio, the manufacturing cost of Ni-Zn ferrite materials and magnetic materials made from them can also be reduced.

[0045] A magnetic material obtained according to the manufacturing method of the first or second embodiment is wound around a conductor to form a coil component. Compared with a component formed from a magnetic material of the same composition using iron oxide powder with a Mn content outside the desired range as raw material, this coil component has a higher relative permeability and superior DC superposition characteristics.

[0046] Example

[0047] The present invention will be further described in detail below through embodiments, but the present invention is not limited to these embodiments.

[0048] [Example 1-1]

[0049] <Fabrication of Magnetic Body and Coil Components>

[0050] First, Fe₂O₃, ZnO, CuO, and NiO containing 0.20% by mass Mn were prepared as raw material powders. Next, these raw material powders were weighed to achieve a composition of 66.2% by mass (49 mol%) for Fe₂O₃, 15.8% by mass (23 mol%) for ZnO, 4.7% by mass (7 mol%) for CuO, and 13.3% by mass (21 mol%) for NiO, and then mixed using a wet mill. Next, the mixed powder obtained by evaporating and removing the dispersion medium was heat-treated at 800°C for 2 hours in an atmospheric atmosphere to obtain a pre-calcined powder. Then, the obtained pre-calcined powder was crushed to achieve a BET specific surface area of ​​2.0–3.0 m². 2 Within the range of / g. Next, distilled water as a dispersion medium and PVA (polyvinyl alcohol) as a binder were added to the crushed pre-calcined powder, and spray-dried using a spray dryer to obtain granulated powder. Next, the obtained granulated powder was fed into a mold and uniaxially compressed under a pressure of 10 MPa to obtain a ring-shaped body. Next, the obtained body was fired at 1100°C for 1 hour in an atmospheric atmosphere to obtain a magnetic body with an outer diameter of 25 mm × inner diameter of 12 mm × thickness of 15 mm. Finally, a wire was wound 20 turns on the obtained magnetic body to obtain the coil component of Example 1-1.

[0051] <Determination of Magnetic Permeability>

[0052] The relative permeability of the obtained coil component was measured using an impedance analyzer (Keysight Technologies, Inc., E4990A) at room temperature, OSC level of 500mV, and frequency of 1MHz. The obtained relative permeability was 450.

[0053] <Determination of DC superposition characteristics and temperature dependence of inductance>

[0054] Using an LCR meter (Keysight Technologies, Inc., E4980A), under conditions of room temperature, OSC level of 20mA, and frequency of 100kHz, the inductance of the aforementioned coil component was measured while gradually increasing the current from 0A. Furthermore, the current value at which the inductance decreased by 30% from the 0A state was defined as the DC superposition characteristic. A higher current value indicates a coil component with superior DC superposition characteristics. The obtained DC superposition characteristic was 515mA.

[0055] Furthermore, using the same apparatus, with the current set to 0A, the inductance was measured by raising the temperature of the coil components from room temperature (25°C) to 150°C. Moreover, the rate of change of inductance from room temperature to 150°C (L...) was also measured. 150℃ -L 25℃) / L 25℃ ×100%) is used as the temperature dependence of inductance. Here, L 25℃ The inductance measured at room temperature (25°C), L 150℃ This refers to the measured inductance value at 150℃. The temperature dependence of the obtained inductance is 65%.

[0056] The above results are compared with those of other embodiments and comparative examples described below in Table 1 and Table 2, respectively. Figures 1-3 middle.

[0057] [Examples 1-2 to 1-9]

[0058] Except that the Fe2O3 powder used as raw material was changed to Fe2O3 powder with Mn content of 0.25% by mass (Examples 1-2), 0.30% by mass (Examples 1-3), 0.40% by mass (Examples 1-4), 0.50% by mass (Examples 1-5), 0.60% by mass (Examples 1-6), 0.70% by mass (Examples 1-7), 0.80% by mass (Examples 1-8), and 0.85% by mass (Examples 1-9), the coil components of Examples 1-2 to 1-9 were made by the same steps as in Example 1-1.

[0059] For the obtained coil components, the temperature dependence of permeability, DC superposition characteristics, and inductance was measured using the same method as in Example 1-1. The results are summarized and shown in Table 1 below. Figures 1-3 middle.

[0060] [Comparative Examples 1-1 to 1-2]

[0061] Except that the Fe2O3 powder used as raw material was changed to Fe2O3 powder with Mn content of 0.15% by mass (Comparative Example 1-1) and 0.90% by mass (Comparative Example 1-2), the coil components of Comparative Examples 1-1 to 1-2 were manufactured by the same steps as in Example 1.

[0062] In Fe2O3 raw material powders commonly used for synthesizing Ni-Zn ferrite materials in electronic components, raw materials with extremely low Mn content are used. This is because Mn is considered a detrimental component that partially reduces insulation resistivity in the formation of Mn-Zn ferrites. Theoretically, such Fe2O3 raw material powders could be made with a purity level of almost Mn-free, with an Mn content of less than 0.001% by mass. However, in actual manufacturing, considering factors such as cost, raw materials with an Mn content of approximately 0.15% by mass are used. Therefore, in Comparative Examples 1-1 described here and Comparative Examples 1-3 to 1-8 described later, raw materials with an Mn content of 0.15% by mass are used as Fe2O3 raw material powders. Furthermore, in Comparative Example 1-2 described here, Fe raw material powder with an Mn content of 0.90% by mass is used to confirm the upper limit of the permissible Mn content. For the obtained coil components, the permeability, DC superposition characteristics, and temperature dependence of inductance were measured using the same method as in Example 1-1. The results are summarized and shown in Table 1 and below. Figures 1-3 middle.

[0063] [Comparative Examples 1-3 to 1-8]

[0064] Except that Mn3O4 powder was further used as an additive in the raw material powder to make the total amount of Mn contained in the mixed powder or Ni-Zn ferrite material the same as in Examples 1-1, 1-3 to 1-6 and 1-8, the coil components of Comparative Examples 1-3 to 1-8 were manufactured by following the same steps as in Comparative Example 1-1. That is, in terms of the total amount of Mn in the Ni-Zn ferrite material, Comparative Example 1-3 is the same as in Example 1-1, Comparative Example 1-4 is the same as in Example 1-3, Comparative Example 1-5 is the same as in Example 1-4, Comparative Example 1-6 is the same as in Example 1-5, Comparative Example 1-7 is the same as in Example 1-6, and Comparative Example 1-8 is the same as in Example 1-8.

[0065] For the obtained coil components, the temperature dependence of permeability, DC superposition characteristics, and inductance was measured using the same method as in Example 1-1. The results are summarized and shown in Table 1 below. Figures 1-3 middle.

[0066] Table 1

[0067]

[0068] According to Table 1 and Figure 1It can be determined that, compared to the coil component of the comparative example, which is manufactured using Fe2O3 powder with low Mn content as a raw material and additionally adding Mn for the industrial synthesis of common Ni-Zn ferrite materials, the coil component of the embodiment, manufactured without additionally adding Mn except for using Fe2O3 powder containing a desired amount of Mn as a raw material, has a higher permeability under the same Mn content conditions. Furthermore, it can be determined that, in the coil component of the comparative example, the permeability decreases sharply with increasing Mn content, while the coil component of the embodiment suppresses this decrease in permeability. In particular, when the Mn content is 0.80% by mass or less, the decrease in permeability is significantly suppressed.

[0069] According to Table 1 and Figure 2 It can be determined that, compared to the coil components of the comparative example used in the industrial synthesis of common Ni-Zn ferrite materials, which are manufactured using Fe2O3 powder with low Mn content as a raw material and with additional Mn added, the coil components of the embodiment manufactured without additional Mn added, except for using Fe2O3 powder containing a desired amount of Mn as a raw material, exhibit superior DC superposition characteristics under the same Mn content conditions. The difference is particularly significant in the range of 0.30% to 0.80% by mass of Mn content.

[0070] According to Table 1 and Figure 3 It can be determined that, compared to the coil component of the comparative example, which is manufactured using Fe2O3 powder with low Mn content as a raw material and additionally adding Mn for industrial synthesis of common Ni-Zn ferrites, the coil component of the embodiment, manufactured without additionally adding Mn except for using Fe2O3 powder containing a desired amount of Mn as a raw material, exhibits a smaller temperature dependence of inductance. Furthermore, it can also be determined that, compared to the coil component of the comparative example, the coil component of the embodiment also shows a smaller change in the temperature dependence of inductance with variations in Mn content.

[0071] As described above, the reason why the coil component of the embodiment manufactured without adding Mn, except for using Fe2O3 powder containing a desired amount of Mn as a raw material, exhibits superior properties compared to the coil component of the comparative example used for industrial synthesis of common Ni-Zn ferrites, which uses Fe2O3 powder with a low Mn content as a raw material and adds Mn, is unclear. The inventors attempted to measure the cross-sections of two types of coil components—one without added Mn and one with added Mn—using EDX to confirm the difference in the in-plane distribution of Mn. However, almost no localized Mn presence was observed in either sample, and the difference could not be confirmed. However, in Fe2O3 powder containing Mn, the fine Mn particles are uniformly dispersed, but it is also considered to improve the properties in some way. That is, when Mn is added as a trace component as a raw material powder, it is difficult to uniformly disperse it in the raw material powder because the amount of this component is less than that of other components. Therefore, microscopic compositional inhomogeneities that are difficult to detect even by EDX are generated in the resulting magnetic material, preventing the full realization of its properties. In contrast, it can be inferred that by using Fe2O3 powder with uniformly dispersed Mn as raw material, the above-mentioned compositional inhomogeneity is reduced, resulting in superior properties.

[0072] [Example 2-1]

[0073] The coil components of Example 2-1 were fabricated using the same steps as in Examples 1-3. Furthermore, in this example, the total Ni and Zn content in the raw material powder was 44 mol%, and the Ni / Zn molar ratio was 0.913.

[0074] For the obtained coil components, the permeability, DC superposition characteristic, and temperature dependence of inductance were measured using the same method as in Examples 1-1. The results showed a relative permeability of 451, a DC superposition characteristic of 536 mA, and a temperature dependence of 72% for the inductance. These results are summarized and shown in Table 2 below. Furthermore, the obtained values ​​for relative permeability and DC superposition characteristic differ slightly from those of Examples 1-3, but these differences are due to minor variations in the manufacturing conditions of the coil components and measurement errors, and are not statistically significant.

[0075] [Examples 2-2, 2-3]

[0076] The Fe2O3 powder used as raw material was changed to Fe2O3 powder with a Mn content of 0.60% by mass (Example 2-2) and 0.80% by mass (Example 2-3), respectively. While maintaining the same total Ni and Zn content of 44 mol% as in Example 2-1, the mixing ratio of the raw material powder was changed to achieve Ni / Zn molar ratios of 0.90 (Example 2-2) and 0.89 (Example 2-3), respectively. Otherwise, coil components for Examples 2-2 and 2-3 were fabricated using the same steps as in Example 2-1. In the actual mixing, Example 2-2 used 15.9% by mass ZnO and 13.2% by mass NiO, while Example 2-3 used 16.0% by mass ZnO and 13.1% by mass NiO.

[0077] For the obtained coil components, the permeability, DC superposition characteristic, and temperature dependence of inductance were measured using the same method as in Examples 1-1. As a result, in the coil components of Example 2-2, the relative permeability was 451, the DC superposition characteristic was 535 mA, and the temperature dependence of inductance was 85%. Furthermore, in the coil components of Example 2-3, the relative permeability was 452, the DC superposition characteristic was 517 mA, and the temperature dependence of inductance was 75%. These results are summarized and shown in Table 2 below.

[0078] [Comparative Examples 2-1 to 2-3]

[0079] The Fe2O3 powder used as a raw material was changed to Fe2O3 powder with a Mn content of 0.15% by mass. While maintaining the same total Ni and Zn content of 44 mol% as in Example 2-1, the mixing ratio of the raw material powder was changed to achieve Ni / Zn molar ratios of 0.92 (Comparative Example 2-1), 0.90 (Comparative Example 2-2), and 0.89 (Comparative Example 2-3), respectively. Otherwise, coil components for Comparative Examples 2-1 to 2-3 were fabricated using the same steps as in Example 2-1. In the actual mixing, Comparative Example 2-1 used 15.8% by mass ZnO and 13.3% by mass NiO; Comparative Example 2-2 used 15.9% by mass ZnO and 13.2% by mass NiO; and Comparative Example 2-3 used 16.0% by mass ZnO and 13.1% by mass NiO.

[0080] Furthermore, in Comparative Examples 2-1 to 2-3 described here and Comparative Examples 2-4 to 2-6 described later, the reason for using Fe2O3 raw material powder with a Mn content of 0.15% by mass as Fe2O3 raw material powder is the same as that in Comparative Examples 1-1 to 1-2. For the obtained coil components, the permeability, DC superposition characteristics, and temperature dependence of inductance were measured according to the same method as in Example 1-1. As a result, in the coil component of Comparative Example 2-1, the relative permeability was 451, and the temperature change rate of the inductance was 64%, which were values ​​similar to those in the above-described examples. However, the DC superposition characteristic was 500 mA, which was lower than that in the above-described examples. The same trend was also confirmed in Comparative Examples 2-2 and 2-3. In Comparative Example 2-2, the relative permeability was 457, the temperature change rate of the inductance was 69%, and the DC superposition characteristic was 492. In Comparative Example 2-3, the relative permeability was 465, the temperature change rate of the inductance was 72%, and the DC superposition characteristic was 484. These results are summarized and shown in Table 2 below.

[0081] In Comparative Examples 2-4 to 2-6 described below, it was also confirmed that when using manganese oxide (Mn3O4) as an additive, even if the Mn content in the Ni-Zn ferrite material is the same as in the above examples, it is not possible to simultaneously achieve excellent DC superposition characteristics and high permeability by adjusting the Ni / Zn molar ratio.

[0082] [Comparative Examples 2-4]

[0083] Except for the following points, the coil components of Comparative Examples 2-4 were manufactured using the same steps as in Example 2-1. The Fe2O3 powder used as a raw material was changed to Fe2O3 powder with a Mn content of 0.15% by mass. Furthermore, Mn3O4 powder was used as an additive in the raw material powder to ensure that the total amount of Mn contained in the mixed powder and even the Ni-Zn ferrite material was consistent with the amount of Fe2O3 powder before the change (Example 2-1). Moreover, while maintaining the same total Ni and Zn content of 44 mol% as in Example 2-1, the Ni / Zn molar ratio was set to 0.86 to ensure that the relative permeability of the coil component was the same as that of the coil component in Example 2-1. In the actual formulation, ZnO was set to 16.3% by mass and NiO to 12.9% by mass.

[0084] For the obtained coil component, the permeability, DC superposition characteristics and temperature dependence of inductance were measured using the same method as in Example 1-1. The results showed that the relative permeability was 452, but the DC superposition characteristics deteriorated to 450 mA and the temperature dependence of inductance deteriorated to 121%.

[0085] [Comparative Examples 2-5]

[0086] Except for the following points, the coil components of Comparative Examples 2-5 were manufactured using the same steps as in Examples 2-2. The Fe2O3 powder used as a raw material was changed to Fe2O3 powder with a Mn content of 0.15% by mass. Furthermore, Mn3O4 powder was further used as an additive in the raw material powder to ensure that the total amount of Mn contained in the mixed powder and even the Ni-Zn ferrite material was consistent with the amount of Fe2O3 powder before the change (Example 2-2). Moreover, while maintaining the same total Ni and Zn content of 44 mol% as in Example 2-1, the Ni / Zn molar ratio was set to 0.82 to ensure that the relative permeability of the coil component was the same as that of the coil component in Example 2-2. In the actual formulation, ZnO was set to 16.6% by mass and NiO to 12.5% ​​by mass.

[0087] For the obtained coil component, the permeability, DC superposition characteristics and temperature dependence of inductance were measured using the same method as in Example 1-1. The results showed that the relative permeability was 450, but the DC superposition characteristics deteriorated to 430 mA and the temperature dependence of inductance deteriorated to 174%.

[0088] [Comparative Examples 2-6]

[0089] Except for the following points, the coil components of Comparative Examples 2-6 were manufactured using the same steps as in Examples 2-3. The Fe2O3 powder used as a raw material was changed to Fe2O3 powder with a Mn content of 0.15% by mass. Furthermore, Mn3O4 powder was further used as an additive in the raw material powder to ensure that the total amount of Mn contained in the mixed powder and even the Ni-Zn ferrite material was consistent with the amount of Mn before the change in Fe2O3 powder (Examples 2-3). Moreover, while maintaining the same total Ni and Zn content of 44 mol% as in Example 2-1, the Ni / Zn molar ratio was reduced to 0.80 to make the relative permeability of the coil component close to that of the coil components of Examples 2-3. In the actual formulation, ZnO was set to 16.8% by mass and NiO to 12.3% by mass.

[0090] For the obtained coil component, the permeability, DC superposition characteristics, and temperature dependence of the inductance were measured using the same method as in Example 1-1. The results showed a relative permeability of only 435. At this point, the DC superposition characteristics deteriorated to 401 mA, and the temperature dependence of the inductance worsened to 188%.

[0091] The results of Comparative Examples 2-4 to 2-6 are shown in Table 2 together with the above-described Examples and Comparative Examples.

[0092] Table 2

[0093]

[0094] Based on the comparison between Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3, it can be determined that the coil components of Examples 2-1 to 2-3, which use Fe2O3 powder containing a desired amount of Mn as a raw material, differ from the coil components of Comparative Examples 2-1 to 2-3, which use Fe2O3 powder with a low Mn content and are used for industrial synthesis of common Ni-Zn ferrite materials. By adjusting the Ni / Zn molar ratio of the Ni-Zn ferrite material, it is possible to achieve both excellent DC superposition characteristics and relative permeability. Based on the results of Comparative Examples 2-1 to 2-3, it can be determined that when using Fe2O3 powder with a low Mn content as a raw material, simply adjusting the Ni / Zn molar ratio of the Ni-Zn ferrite material is insufficient to manufacture a coil component that maintains excellent DC superposition characteristics while preserving relative permeability. Furthermore, by adjusting the Ni / Zn molar ratio as in Examples 2-1 to 2-3, the amount of expensive raw material NiO used can be reduced, thereby controlling raw material costs.

[0095] Furthermore, based on the comparisons between Example 2-1 and Comparative Example 2-4, Example 2-2 and Comparative Example 2-5, and Example 2-3 and Comparative Example 2-6, it can be determined that the coil component of the embodiment that does not add Mn except for using Fe2O3 powder containing a desired amount of Mn as a raw material differs from the coil component of the comparative example used for industrial synthesis of common Ni-Zn ferrites, which uses Fe2O3 powder with low Mn content as a raw material and adds Mn. By adjusting the Ni / Zn molar ratio of the Ni-Zn ferrite material, it is possible to achieve both excellent DC superposition characteristics and relative permeability. Moreover, it can be determined that when using Fe2O3 powder with low Mn content as a raw material, even if Mn is added to increase the total amount of Mn in the Ni-Zn ferrite material, it is not possible to manufacture a coil component that maintains excellent DC superposition characteristics and low temperature dependence of inductance while maintaining relative permeability simply by adjusting the Ni / Zn molar ratio.

[0096] Furthermore, based on the comparison of Examples 2-1 to 2-3, it can be determined that the higher the Mn content of the Fe2O3 powder used as a raw material, the smaller the Ni / Zn molar ratio with the desired relative permeability can be obtained.

[0097] As described above, the coil component of the embodiment, manufactured without adding Mn other than using Fe2O3 powder containing a desired amount of Mn as a raw material, differs from the coil component of the comparative example used for industrial synthesis of common Ni-Zn ferrites, which uses Fe2O3 powder with a low Mn content as a raw material and adds Mn. The reason for its superior DC superposition characteristics is unclear. However, based on the examples and comparative examples of the first embodiment described above, it is speculated that in the second embodiment, the uniform dispersion of fine Mn-containing particles in the Mn-containing Fe2O3 powder may improve the characteristics in some way.

[0098] Industrial availability

[0099] According to the present invention, a coil component with excellent DC superposition characteristics and permeability can be provided even without the use of additives other than the main component. Furthermore, according to a preferred embodiment of the present invention, the DC superposition characteristics and permeability are easily adjustable. Therefore, high-performance coil components can be manufactured through simple operations, and the present invention is useful in reducing manufacturing costs or, consequently, development costs. Additionally, the present invention is considered useful in reducing microscopic compositional inhomogeneities in magnetic materials and suppressing deviations in the characteristics of the manufactured coil components. Moreover, according to a preferred embodiment of the present invention, the amount of expensive Ni-containing raw materials used in the raw material powder for manufacturing Ni-Zn ferrite materials can be reduced, thus reducing manufacturing costs.

Claims

1. A manufacturing method of a magnetic body made of a ferrite material containing Fe, Ni, Zn, and Cu, characterized by: manufacturing the magnetic body without adding Mn separately, using an iron oxide powder having a Mn content of 0.30 to 0.80 mass% as a raw material powder, the ferrite material containing Fe, Zn, Ni, and Cu in the following proportions, in terms of Fe2O3, ZnO, NiO, and CuO: Fe2O3 58.9 to 66.9 mass%; ZnO 9.5 to 25.4 mass%; NiO 8.6 to 23.6 mass%; CuO 0.6 to 8.6 mass%.

2. A manufacturing method of a magnetic body made of a ferrite material containing Fe, Ni, Zn, and Cu, characterized by: manufacturing the magnetic body without adding Mn separately, using an iron oxide powder having a Mn content of 0.30 mass% or more as a raw material powder, and determining a molar ratio of Ni to Zn (Ni / Zn) in the ferrite material based on the Mn content in the iron oxide powder, and adjusting the raw material powder to obtain the molar ratio, the ferrite material containing Fe, Zn, Ni, and Cu in the following proportions, in terms of Fe2O3, ZnO, NiO, and CuO: Fe2O3 58.9 to 66.9 mass%; ZnO 9.5 to 25.4 mass%; NiO 8.6 to 23.6 mass%; CuO 0.6 to 8.6 mass%.

3. The manufacturing method of a magnetic body according to claim 2, characterized in that: the Mn content in the iron oxide powder is 0.80 mass% or less.

4. A coil member characterized by: being made by combining a magnetic body obtained by the manufacturing method of a magnetic body according to any one of claims 1 to 3 and a conductor. ​ ​

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