Ferrite compositions, ferrite sintered bodies, and electronic components

Abstract

To provide: a ferrite sintered body capable of being suitably used in a high frequency band and having excellent mechanical strength; a composition thereof; and an electronic component having the composition.SOLUTION: A ferrite composition has a main component and a sub-component. The main component comprises: 40.5 to 50.0 mol% of iron oxide in terms of Fe2O3; 6.0 to 14.0 mol% of copper oxide in terms of CuO; 7.0 to 25.0 mol% of zinc oxide in terms of ZnO; and nickel oxide as the remainder. Based on 100 pts.wt. of the main component, the sub-component comprises: 3.1 to 10.0 pts.wt of cobalt oxide in terms of Co3O4; 0.5 to 4.0 pts.wt of tin oxide in terms of SnO2; and 0.50 pt.wt or less (including 0) of bismuth oxide in terms of Bi2O3. When A=(α-18) / β, where α is a content expressed by mol% of zinc oxide in terms of ZnO in the main component and β is a content by weight of cobalt oxide in terms of Co3O4 based on 100 pts.wt. of the main component, A is -3.5 or more and 1.0 or less.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a ferrite composition, a ferrite sintered body, and an electronic component. 【Background Art】 【0002】 For example, Patent Document 1 shown below discloses a ferrite composition containing Fe2O3, NiO, CuO, ZnO, and CoO in a predetermined ratio, and it is expected that noise can be favorably removed in a high-frequency band. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2008-300548 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In view of such a situation, the present invention has been made, and its object is to provide a ferrite sintered body that can be suitably used in a high-frequency band and has excellent mechanical strength, its composition, and an electronic component having the composition. 【Means for Solving the Problems】 【0005】 As a result of intensive studies on a ferrite composition used for an electronic component suitable in a high-frequency band, the present inventors have found that in the case of a ferrite composition containing a large amount of Co oxide, in an electronic component manufactured using this ferrite composition, the strength of the element body (sintered body) tends to be insufficient, and problems such as cracks are likely to occur, resulting in a problem that the reliability of the electronic component decreases. 【0006】 When obtaining electronic components to which ferrite compositions are applied, if the strength of the sintered body made of the ferrite composition is insufficient, it is likely to have insufficient durability against mechanical stresses such as bending and tensile stress, which can lead to defects such as chipping and cracking. Therefore, the development of ferrite compositions that can exhibit higher strength is desired. 【0007】 As a result of diligent research to solve the above-mentioned problems, the present inventors have found that a ferrite sintered body having a ferrite composition in which Co oxide and Sn oxide are within a predetermined numerical range has high bending strength and a large real part μ' of complex permeability at high frequencies (for example, around 900 MHz, i.e., 700 MHz to 1.7 GHz), thus completing the present invention. 【0008】 In other words, the ferrite composition according to the present invention is A ferrite composition having a main component and a secondary component, The aforementioned main components consist of 40.5 to 50.0 mol% iron oxide (in Fe2O3 equivalent), 6.0 to 14.0 mol% copper oxide (in CuO equivalent), 7.0 to 25.0 mol% zinc oxide (in ZnO equivalent), and the remainder being nickel oxide. With respect to 100 parts by weight of the main component, the minor components contain cobalt oxide in amounts of 3.1 to 10.0 parts by weight (in terms of Co3 O4), tin oxide in amounts of 0.5 to 4.0 parts by weight (in terms of SnO2), and bismuth oxide in amounts of 0.50 parts by weight or less (including 0) (in terms of Bi2 O3). When α is the content of the zinc oxide in the main component expressed in mol% in terms of ZnO, and β is the content of the cobalt oxide in terms of Co3O4 per 100 parts by weight of the main component, and A = (α - 18) / β, A is between -3.5 and 1.0. 【0009】 Preferably, when γ is the weight content of the tin oxide in terms of SnO2 relative to 100 parts by weight of the main component, β / γ may be 1.6 or more. 【0010】 Preferably, the ferrite sintered body has the above-mentioned ferrite composition. 【0011】 Preferably, the electronic component has the above-mentioned ferrite composition. [Brief explanation of the drawing] 【0012】 [Figure 1] Figure 1 is an internal perspective view of a chip coil as an electronic component according to one embodiment of the present invention. [Figure 2] Figure 2 is an internal perspective view of a chip coil as an electronic component according to another embodiment of the present invention. [Modes for carrying out the invention] 【0013】 Embodiments of the present invention will be described below. As shown in Figure 1, a chip coil 1 as an electronic component according to one embodiment of the present invention has a chip body 4 in which ceramic layers 2 and internal electrode layers 3 are alternately stacked in the Y-axis direction. 【0014】 Each internal electrode layer 3 has a square ring or C-shape and is spirally connected by through-hole electrodes (not shown) or stepped electrodes for internal electrode connection that penetrate the adjacent ceramic layer 2, thereby forming a coil conductor 30. 【0015】 Terminal electrodes 5, 5 are formed at both ends of the chip body 4 in the Y-axis direction. The end of a through-hole electrode 6 for terminal connection, which penetrates the stacked ceramic layer 2, is connected to each terminal electrode 5, and each terminal electrode 5, 5 is connected to both ends of a coil conductor 30 that constitutes a closed magnetic circuit coil (winding pattern). 【0016】 In this embodiment, the stacking direction of the ceramic layer 2 and the internal electrode layer 3 coincides with the Y-axis, and the end faces of the terminal electrodes 5, 5 are parallel to the X-axis and Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other. In the chip coil 1 shown in Figure 1, the winding axis of the coil conductor 30 substantially coincides with the Y-axis. 【0017】 There are no particular restrictions on the outer shape and dimensions of the chip body 4, which can be appropriately set according to the application and are not particularly limited. Usually, the outer shape is approximately a rectangular parallelepiped shape. For example, the X-axis dimension is 0.15 to 0.8 mm, the Y-axis dimension is 0.3 to 1.6 mm, and the Z-axis dimension is 0.1 to 1.0 mm. 【0018】 Also, there are no particular restrictions on the thickness between electrodes and the base thickness of the ceramic layer 2. The thickness between electrodes (the interval between the internal electrode layers 3 and 3) can be set to 3 to 50 μm, and the base thickness (the length in the Y-axis direction of the through-hole electrode 6 for terminal connection) can be set to about 5 to 300 μm. 【0019】 In this embodiment, the terminal electrode 5 is not particularly limited and is formed by attaching a conductive paste mainly composed of Ag, Pd, etc. to the outer surface of the main body 4, baking it, and then performing electroplating. For electroplating, Cu, Ni, Sn, etc. can be used. 【0020】 The coil conductor 30 contains Ag (including Ag alloys), and is composed of, for example, pure Ag, Ag-Pd alloys, etc. As sub-components of the coil conductor, Zr, Fe, Mn, Ti, and their oxides can be included. 【0021】 The ceramic layer 2 is composed of a ferrite composition according to an embodiment of the present invention. Hereinafter, the ferrite composition will be described in detail. 【0022】 The ferrite composition according to this embodiment contains iron oxide, copper oxide, zinc oxide, and nickel oxide as main components. 【0023】 In 100 mol% of the main component, the iron oxide content is 40.5 mol% or more, preferably 42.0 mol% or more, more preferably 43.0 mol% or more, and 50.0 mol% or less, preferably 48.0 mol% or less, and more preferably 47.0 mol% or less, in terms of Fe2O3. If the iron oxide content is too low, the real part μ' of the complex permeability tends to decrease at high frequencies around 900 MHz, and the resistivity tends to decrease. If the iron oxide content is too high, the mechanical strength tends to decrease, and the temperature characteristics of the initial permeability μi tend to deteriorate. 【0024】 In 100 mol% of the main component, the copper oxide content is 6.0 mol% or more, preferably 8.0 mol% or more, and 14.0 mol% or less, preferably 12.5 mol% or less, in terms of CuO. If the copper oxide content is too low, the bending strength tends to decrease and the resistivity tends to decrease. If the copper oxide content is too high, the real part μ' of the complex permeability tends to decrease and the resistivity tends to decrease. 【0025】 In 100 mol% of the main component, the zinc oxide content (α) is 7.0 mol% or more, preferably 9.0 mol% or more, more preferably 11.0 mol% or more, and 25.0 mol% or less, preferably 23.0 mol% or less, in terms of ZnO. If the zinc oxide content is too low, the resistivity tends to decrease. If the zinc oxide content is too high, the Curie temperature tends to decrease too much. In addition, the real part μ' of the complex permeability at high frequencies around 900 MHz tends to decrease, and the resistivity also tends to decrease. 【0026】 The remainder of the main component consists of nickel oxide. While there are no particular restrictions on the nickel oxide content in the main component, it is typically between 15.0 and 40.0 mol% in terms of NiO. If the nickel oxide content is too low, the Curie temperature tends to decrease excessively. Conversely, if the nickel oxide content is too high compared to the iron oxide content, the real part μ' of the complex permeability tends to decrease at high frequencies around 900 MHz. 【0027】 The ferrite composition according to this embodiment contains, in addition to the main components described above, at least cobalt oxide and tin oxide as minor components. 【0028】 The cobalt oxide content (β) is 3.1 parts by weight or more, preferably 3.5 parts by weight or more, and 10.0 parts by weight or less, preferably 8.0 parts by weight or less, in terms of Co3 O4, per 100 parts by weight of the main component. If the cobalt oxide content is too low, the real part μ' of the complex permeability tends to decrease at high frequencies around 900 MHz. If the cobalt oxide content is too high, the real part μ' of the complex permeability tends to decrease, and the resistivity tends to worsen. 【0029】 The tin oxide content (γ) is 0.5 parts by weight or more, preferably 0.8 parts by weight or more, and 4.0 parts by weight or less, preferably 3.0 parts by weight or less, in terms of SnO2, per 100 parts by weight of the main component. If the tin oxide content is too low, the improvement effect on bending strength and the improvement effect on the temperature change rate of the initial permeability μi tend not to be sufficiently obtained. If the tin oxide content is too high, the real part μ' of the complex permeability at high frequencies around 900 MHz tends to decrease, the resistivity decreases, and the bending strength tends to decrease. 【0030】 In this embodiment, it is preferable that the relationship between the zinc oxide content and the cobalt oxide content satisfies the following equation. That is, if α is the content of zinc oxide in the main component expressed in mole percent in terms of ZnO, and β is the content of cobalt oxide in terms of Co3O4 per 100 parts by weight of the main component, and A = (α - 18) / β, then A is between -3.5 and 1.0, preferably between -3.5 and 0.9. If A is too low or too high, the real part μ' of the complex permeability at high frequencies around 900 MHz tends to be low. 【0031】 In this embodiment, when γ is the content (parts by weight) of tin oxide in terms of SnO2 relative to 100 parts by weight of the main component, β / γ is preferably 1.6 or more, and more preferably 1.6 or more and 10.0 or less. By setting it within this range, it becomes possible to further increase the real part μ' of the complex permeability at high frequencies around 900 MHz, and the bending strength is also improved. 【0032】 Furthermore, the ferrite composition according to this embodiment may also contain bismuth oxide in addition to the above-mentioned auxiliary components. The bismuth oxide content is preferably 0.5 parts by weight or less (including 0), more preferably less than 0.3 parts by weight (including 0), and particularly preferably less than 0.2 parts by weight (including 0), in terms of Bi2O3, per 100 parts by weight of the main component. If the bismuth oxide content is too high, the bending strength tends to decrease. This is thought to be because grain growth progresses too much. 【0033】 Furthermore, the ferrite composition according to this embodiment may also contain silicon oxide in addition to the above components. The silicon oxide content is not particularly limited, but may be preferably 0.3 parts by weight (including 0) or less in terms of SiO2 per 100 parts by weight of the main component, may be less than 0.2 parts by weight (including 0), may be less than 0.15 parts by weight (including 0), or may be less than 0.1 parts by weight (including 0). 【0034】 Furthermore, the ferrite composition according to this embodiment may also contain additional components such as manganese oxides like Mn3O4, zirconium oxides, magnesium oxides, and glass compounds, in addition to the above-mentioned components, to the extent that they do not impair the effects of this embodiment. The content of these additional components is not particularly limited, but is, for example, 1 part by weight or less (including 0). 【0035】 Furthermore, the ferrite composition according to this embodiment may contain oxides of unavoidable impurity elements. 【0036】 Specifically, unavoidable impurity elements include typical metal elements such as C, S, Cl, As, Se, Br, Te, I, Li, Na, Mg, Al, Ca, Ga, Ge, Sr, Cd, In, Sb, Ba, and Pb, as well as transition metal elements such as Sc, Ti, V, Cr, Y, Nb, Mo, Pd, Ag, Hf, and Ta. Furthermore, it is preferable that oxides of unavoidable impurity elements are present in the ferrite composition in an amount of approximately 0.05 parts by weight or less. 【0037】 The average particle size of the crystalline particles in the ferrite composition according to this embodiment is not particularly limited, but is, for example, 0.2 to 2.0 μm. The content of each main component and each minor component does not change much during the manufacturing process of the ferrite composition, from the raw material powder stage to after calcination. 【0038】 In the ferrite composition according to this embodiment, in addition to the composition range of the main component being controlled within the above range, tin oxide and cobalt oxide are included as minor components within the above range, and A is controlled within a predetermined range. Therefore, in the ferrite composition according to this embodiment, the real part μ' of the complex permeability is large, especially at high frequencies around 900 MHz, making it possible to obtain a ferrite sintered body with high mechanical strength such as bending strength and excellent reliability. Furthermore, in the ferrite composition according to this embodiment, it is possible to obtain a ferrite sintered body with high resistivity and good temperature characteristics of the initial permeability μi. 【0039】 The large real part μ' of the complex permeability of the ferrite sintered body results in a high impedance for chip coils (chip beads) using the ferrite sintered body. Furthermore, the large real part μ' of the complex permeability, especially at high frequencies around 900 MHz, leads to particularly high impedance at high frequencies. 【0040】 Generally, due to the snake limit, the real part μ' of the complex permeability decreases at high frequencies, making it difficult to obtain high impedance at high frequencies. In this embodiment, the real part μ' of the complex permeability can be improved at high frequencies, making it suitable for use in chip coils (chip beads) used at high frequencies, and providing a significant noise reduction effect, especially at high frequencies. Furthermore, the ferrite sintered body made of the ferrite composition according to this embodiment can be used not only as a chip coil, but also as a composite electronic component that combines a coil with other elements such as a capacitor, such as an inductor or an LC composite component. 【0041】 Next, an example of a method for producing the ferrite composition according to this embodiment will be described. First, the starting materials (the main component raw material and the secondary component raw material) are weighed and mixed in a predetermined composition ratio to obtain a raw material mixture. Mixing methods include, for example, wet mixing using a ball mill or dry mixing using a dry mixer. It is preferable to use starting materials with an average particle size of 0.05 to 3.0 μm. 【0042】 As the main raw materials, iron oxide (α-Fe2O3), copper oxide (CuO), nickel oxide (NiO), zinc oxide (ZnO), or composite oxides can be used. Furthermore, various compounds that become the above-mentioned oxides or composite oxides upon firing can also be used. Examples of substances that become the above-mentioned oxides upon firing include elemental metals, carbonates, oxalates, nitrates, hydroxides, halides, organometallic compounds, and so on. 【0043】 As raw materials for the auxiliary components, tin oxide and cobalt oxide can be used, and bismuth oxide or other oxides can be used as needed. There are no particular limitations on the oxides used as raw materials for the auxiliary components, and composite oxides can be used. Furthermore, various compounds that become the above-mentioned oxides or composite oxides upon firing can also be used. Examples of substances that become the above-mentioned oxides upon firing include elemental metals, carbonates, oxalates, nitrates, hydroxides, halides, organometallic compounds, etc. 【0044】 Next, the raw material mixture is calcined to obtain calcined material. Calcination is performed to convert the raw material mixture into a form suitable for subsequent processes by causing thermal decomposition of the raw materials, homogenization of the components, formation of ferrite, disappearance of ultrafine powder through sintering, and grain growth to an appropriate particle size. There are no particular restrictions on the calcination time or calcination temperature. Calcination is usually performed in the atmosphere (air), but it may also be performed in an atmosphere with a lower oxygen partial pressure than the atmosphere. 【0045】 Next, the calcined material is pulverized to obtain pulverized material. Pulverization is performed to break down the agglomeration of the calcined material and obtain a powder with appropriate sinterability. If the calcined material forms large lumps, coarse pulverization is performed first, followed by wet pulverization using a ball mill or attritor. Wet pulverization is performed until the average particle size of the pulverized material is preferably about 0.1 to 1.0 μm. 【0046】 In the above-described method for manufacturing the pulverized material, the main component powder and the secondary component powder are all mixed together before calcination. However, the method for manufacturing the pulverized material is not limited to the above method. For example, some of the raw material powders mixed before calcination can be mixed after calcination, during the pulverization of the calcined material, instead of being mixed with the other raw material powders before calcination. 【0047】 Next, the chip coil 1 shown in Figure 1 according to this embodiment is manufactured using the obtained crushed material. 【0048】 First, the obtained pulverized material is slurryed with a solvent and additives such as a binder to produce a ferrite paste. Then, the ferrite paste and an internal electrode paste containing Ag are alternately printed and laminated, and the laminate is then fired to form the chip body 4 (printing method). Alternatively, a green sheet may be made using the ferrite paste, the internal electrode paste may be printed on the surface of the green sheet, and the laminate formed by laminating these sheets may be fired to form the chip body 4 (sheet method). In any case, after the chip body is formed, the terminal electrodes 5 can be formed by baking or plating. 【0049】 There are no restrictions on the binder and solvent content in the ferrite paste. For example, the binder content can be set in the range of 1 to 10% by weight, and the solvent content in the range of 10 to 50% by weight. In addition, dispersants, plasticizers, etc. can be included in the paste in a range of 10% by weight or less, as needed. Internal electrode pastes containing Ag, etc., can be prepared in the same manner. Furthermore, there are no particular restrictions on firing conditions, but when Ag, etc., is included in the internal electrode layer, the firing temperature is preferably 930°C or lower, and more preferably 900°C or lower. 【0050】 The ferrite composition according to this embodiment also exhibits excellent sinterability, enabling low-temperature sintering. For example, it can be sintered at approximately 900°C (950°C or lower), which is below the melting point of Ag, which can be used as an internal electrode, making it possible to easily manufacture a chip coil 1 as shown in Figure 1. 【0051】 It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention. 【0052】 For example, the ceramic layer 2 of the chip coil 1a shown in Figure 2 may be made using the ferrite composition of the embodiment described above. The chip coil 1a shown in Figure 2 has a chip body 4a in which the ceramic layer 2 and the internal electrode layer 3a are alternately stacked in the Z-axis direction. 【0053】 Each internal electrode layer 3a has a square ring or C-shape and is spirally connected by through-hole electrodes (not shown) or stepped electrodes for internal electrode connection that penetrate the adjacent ceramic layer 2, forming a coil conductor 30a. 【0054】 Terminal electrodes 5, 5 are formed at both ends of the chip body 4a in the Y-axis direction. The ends of the lead electrodes 6a located above and below in the Z-axis direction are connected to each terminal electrode 5, and each terminal electrode 5, 5 is connected to both ends of the coil conductor 30a that constitutes the closed magnetic circuit coil. 【0055】 In this embodiment, the stacking direction of the ceramic layer 2 and the internal electrode layer 3 coincides with the Z-axis, and the end faces of the terminal electrodes 5, 5 are parallel to the X-axis and Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other. In the chip coil 1a shown in Figure 2, the winding axis of the coil conductor 30a approximately coincides with the Z-axis. 【0056】 In the chip coil 1 shown in Figure 1, the winding axis of the coil conductor 30 is in the Y-axis direction, which is the longitudinal direction of the chip body 4. Therefore, compared to the chip coil 1a shown in Figure 2, it is possible to increase the number of turns, which has the advantage of making it easier to achieve high impedance up to high frequency bands. In the chip coil 1a shown in Figure 2, the other configurations and effects are the same as those of the chip coil 1 shown in Figure 1. 【0057】 Furthermore, the ferrite composition of this embodiment can be used in electronic components other than the chip coil shown in Figure 1 or Figure 2. For example, the ferrite composition of this embodiment can be used as a ceramic layer laminated together with a coil conductor. Also, the chip coil does not necessarily have to be a laminated type chip coil; the ferrite composition of this embodiment can also be used in a wound type chip coil. In addition, the ferrite composition of this embodiment can be used in composite electronic components that combine a coil with other elements such as a capacitor, such as an LC composite component. Furthermore, the ferrite composition of this embodiment can also be used in other electronic components where ferrite is commonly used, such as capacitors. [Examples] 【0058】 The present invention will be described below based on more detailed examples, but it is not limited to these examples. 【0059】 Example 1 First, Fe2O3, NiO, CuO, and ZnO were prepared as the main components of the ferrite composition. SnO2 and Co3O4 were prepared as the secondary components. The average particle size of the starting materials was in the range of 0.1 to 3.0 μm. 【0060】 Next, the prepared main component powders and secondary component powders were weighed to form a sintered body with the compositions shown in Tables 1A to 2. 【0061】 In the table, α represents the content of zinc oxide in the main component expressed as mol% in terms of ZnO, and β represents the content of cobalt oxide in terms of Co3 O4 per 100 parts by weight of the main component. The weighing was performed so that A = (α - 18) / β equals the value in the table. In addition, γ represents the content of tin oxide in terms of SnO2 per 100 parts by weight of the main component. The weighing was performed so that β / γ equals the value in the table. 【0062】 After weighing, the prepared main component raw materials were wet-mixed in a ball mill for 24 hours to obtain a raw material mixture. Next, the obtained raw material mixture was dried and then calcined in air to obtain a calcined product. The calcination temperature was appropriately selected within the range of 500 to 900°C depending on the composition of the raw material mixture. Subsequently, the calcined product was ground in a ball mill while adding the aforementioned auxiliary component raw materials to obtain a ground powder. 【0063】 Next, after drying the pulverized powder, 10.0 parts by weight of a 6 wt% aqueous solution of polyvinyl alcohol as a binder was added to 100 parts by weight of the pulverized powder to granulate it. These granules were then pressure-molded to obtain toroidal-shaped molded bodies, disc-shaped molded bodies, and rectangular prism-shaped molded bodies, corresponding to sample numbers 1 to 80, respectively. 【0064】 Two types of toroidal molded bodies were prepared, corresponding to sample numbers 1 through 80: Toroidal A (dimensions: outer diameter 8 mm x inner diameter 4 mm x height 2.5 mm) and Toroidal B (dimensions: outer diameter 13 mm x inner diameter 6 mm x height 3 mm). In addition, a disc-shaped molded body with dimensions of 12 mm diameter x 2 mm height was prepared, corresponding to sample numbers 1 through 80. Furthermore, a rectangular prism-shaped molded body with dimensions of 5 mm width x 25 mm length x 3 mm thickness was prepared, corresponding to sample numbers 1 through 80. 【0065】 Next, each of these molded bodies was fired in air at 860-900°C (below the melting point of Ag, 962°C) for 2 hours to obtain toroidal A sample, toroidal B sample, disk sample, and rectangular prism-shaped sample as sintered bodies. Furthermore, the following characteristics were evaluated for each of the obtained samples. It should be noted that there was almost no change in composition between the weighed raw material powder and the molded bodies after firing using an X-ray fluorescence analyzer. This was confirmed by [method / method]. 【0066】 (The real part μ' of the complex permeability) The permeability μ' of toroidal A samples was measured using an RF impedance analyzer (Keysight Technologies E4991A) and a test fixture (Keysight Technologies 16454A). The measurement conditions were a measurement frequency of 10 MHz and 900 MHz, and a measurement temperature of 25°C. In this example, a μ' of 4.7 or higher at 10 MHz and a μ' of 5.2 or higher at 900 MHz were considered good. A μ' of 5.5 or higher at 900 MHz was more preferable. 【0067】 (Temperature change rate) A copper wire was wound around a toroidal B sample 20 times, and the initial permeability μi at room temperature (25°C) and the initial permeability μi at 85°C were measured using an LF impedance analyzer (Keysight Technologies E4192A). Then, the rate of change of the initial permeability μi at 85°C was determined, using the initial permeability μi at room temperature as the reference. 【0068】 (specific resistance ρ) In-Ga electrodes were applied to both sides of a disk sample, and the DC resistance was measured to determine the resistivity ρ (unit: Ω·m). The measurement was performed using an IR meter (ADC R8340). The resistivity ρ was 1.0 × 10⁻⁶. 6 A reading of Ω·m or higher (1.0E+06Ω·m or higher) was considered good. 【0069】 (Bending strength) A three-point bending test was performed on a rectangular prism-shaped sample to induce fracture, and the bending strength at the time of fracture was measured. A universal material testing machine (Instron Japan 5543) was used for the three-point bending test. A bending strength of 140 MPa or higher was considered good. 【0070】 The test results (evaluation results) are shown in Tables 1A to 2. 【0071】 (Rating 1) As shown in Table 1A, sample numbers 1 to 17, provided that components other than Fe2O3 satisfy the specified conditions, the following was confirmed. Specifically, compared to the comparative example with a Fe2O3 content of less than 40.5 mol% (sample number 1), the example with a Fe2O3 content of 40.5 to 50.0 mol% showed improved μ' at 900 MHz, as well as improved resistivity and flexural strength. Furthermore, compared to the comparative example with a Fe2O3 content of more than 50.0 mol% (sample number 17), the example with a Fe2O3 content of 40.5 to 50.0 mol% showed improved μ' at 900 MHz, as well as improved flexural strength. 【0072】 Furthermore, even when the Fe2O3 content was within the range of 40.5 to 50.0 mol%, comparative examples with a SnO2 content (γ) less than 0.5 parts by weight (sample numbers 3 to 5, 7, and 9) showed a decrease in bending strength and a tendency for the temperature characteristics of the initial permeability μi to deteriorate compared to the examples. In addition, even when the Fe2O3 content was within the range of 40.5 to 50.0 mol%, comparative example (sample number 16) with a ZnO content (α) higher than 25.0 mol% showed a decrease in μ' at 900 MHz. 【0073】 As shown in Table 1A, sample numbers 18-22, in comparative examples (sample numbers 18-22) with a SnO2 content (γ) less than 0.5 parts by weight, it was confirmed that the bending strength decreased, the temperature characteristics of the initial permeability μi deteriorated, or μ' at 900 MHz deteriorated compared to the examples. 【0074】 As shown in Table 1B, sample numbers 23 to 41, provided that the components other than ZnO satisfy the specified conditions, the following was confirmed. Specifically, in the examples with a ZnO content (α) of 7.0 to 25.0 mol%, the resistivity was improved compared to the comparative example (sample number 23) with a ZnO content (α) of 5.0 mol%. Furthermore, compared to the comparative example (sample number 41) with a ZnO content (α) of 27.0 mol%, the μ' at 900 MHz was improved, and the resistivity was also improved in the examples with a ZnO content (α) of 7.0 to 25.0 mol%. 【0075】 Furthermore, even when the ZnO content was within the range of 7.0 to 25.0 mol%, it was confirmed that μ' at 900 MHz decreased in comparative examples (sample numbers 25 and 26) where the Co3 O4 content (β) was less than 3.1 parts by weight. In addition, even when the ZnO content was within the range of 7.0 to 25.0 mol%, it was confirmed that μ' at 900 MHz decreased compared to the examples in comparative examples (sample number 25) where the value of A, expressed as A = (α - 18) / β, was less than -3.5, and in comparative examples (sample number 38) where it was greater than 1.0. 【0076】 Furthermore, by comparing the example with a β / γ ratio of less than 1.6 (sample number 30) with the example with a β / γ ratio of 1.6 or higher (sample numbers 24, 27-29, 31-37, 39-40), it was confirmed that increasing the β / γ ratio to 1.6 or higher improves μ' at least at 900 MHz. 【0077】 As shown in Table 1C, sample numbers 42-63, provided that components other than CuO satisfy the specified conditions, the following was confirmed. Specifically, in the examples with a CuO content of 6.0-14.0 mol%, improvements were observed in μ' at 900 MHz, resistivity, and flexural strength compared to the comparative example (sample number 42) with a CuO content of 5.5 mol%. Furthermore, compared to the comparative example (sample number 51) with a CuO content of 15.5 mol%, improvements were observed in μ' at 10 MHz and 900 MHz, as well as improvements in resistivity and flexural strength. 【0078】 Furthermore, even when the CuO content was within the range of 6.0 to 14.0 mol%, in the comparative example (sample number 57) with an Fe2O3 content of less than 40.5 mol%, it was confirmed that μ' at 900 MHz decreased, as did the resistivity and flexural strength. It is thought that the reason why the comparative example related to sample number 57 in Table 1C had higher flexural strength compared to the comparative example related to sample number 1 in Table 1A was because the Co3O4 content (β) was low, at 5.0 parts by weight or less. 【0079】 As shown in Table 2, sample numbers 64-80, provided that components other than SnO2 satisfy the specified conditions, the following was confirmed. Specifically, in the examples with a SnO2 content of 0.5 to 4.0 parts by weight, the temperature change rate of the initial permeability μi and the bending strength were improved compared to the comparative example with a SnO2 content of less than 0.5 parts by weight (sample number 64). Furthermore, compared to the comparative example with a SnO2 content of 4.5 parts by weight (sample number 72), the μ' at 900 MHz was improved, and the resistivity and bending strength were also improved. 【0080】 Furthermore, compared to the examples where β / γ was less than 1.6 (sample numbers 71 and 76), it was confirmed that the μ' at 900 MHz was improved in the examples where β / γ was 1.6 or higher (sample numbers 65-70, 73-74, 77-78 and 80). 【0081】 Example 2 Except for adding Bi2O3 as a secondary component to the sintered body in a quantity that matches the composition shown in Table 3, a sintered body sample was prepared in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 3. 【0082】 As shown in Table 3, it was confirmed that while the bending strength decreased with increasing Bi2O3 content, the μ' at 900MHz improved and the resistivity also improved. 【0083】 Example 3 A sintered body sample was prepared in the same manner as in Example 1, except that SiO2 was added as a secondary component, weighed to achieve the composition of the sintered body shown in Table 4. The same evaluation was performed as in Example 1. The results are shown in Table 4. 【0084】 As shown in Table 4, even with a relatively small amount of SiO2, it was confirmed that the μ' at 900 MHz, the temperature change rate of the initial permeability μi, resistivity, and bending strength were at a sufficiently satisfactory level. 【0085】 [Table 1A] 【0086】 [Table 1B] 【0087】 [Table 1C] 【0088】 [Table 2] 【0089】 [Table 3] 【0090】 [Table 4] [Explanation of symbols] 【0091】 1,1a… Chip coil 2… Ceramic layer 3,3a… Internal electrode layer 4,4a… Chip body 5…Terminal electrode 6… Through-hole electrodes for terminal connection 6a… Drawer electrode 30,30a… Coil conductor

Claims

[Claim 1] A ferrite composition having a main component and a secondary component, The aforementioned main component contains 40.5 to 50.0 mol% iron oxide (in terms of Fe₂O₃), 6.0 to 14.0 mol% copper oxide (in terms of CuO), 7.0 to 25.0 mol% zinc oxide (in terms of ZnO), and the remainder being nickel oxide. With respect to 100 parts by weight of the main component, the minor component contains cobalt oxide in the amount of 3.1 to 10.0 parts by weight in terms of Co3 O4, tin oxide in the amount of 0.5 to 4.0 parts by weight in terms of SnO2, bismuth oxide in the amount of 0.50 parts by weight or less (including 0) in terms of Bi2 O3, and silicon oxide in the amount of less than 0.2 parts by weight (including 0) in terms of SiO2. When α is the content of the zinc oxide in the main component expressed in mol% in terms of ZnO, and β is the content of the cobalt oxide in terms of Co3O4 per 100 parts by weight of the main component, and A = (α - 18) / β, A is a ferrite composition having a value of -3.5 or higher and 1.0 or lower. [Claim 2] The ferrite composition according to claim 1, wherein β / γ is 1.6 or more, when γ is the content of the tin oxide in terms of SnO2 relative to 100 parts by weight of the main component. [Claim 3] A ferrite sintered body having the ferrite composition according to claim 1 or 2. [Claim 4] An electronic component having the ferrite composition according to claim 1 or 2.

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