JP2015151299A - Ferrite composition, ferrite core and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a ferrite composition having high initial permeability and excellent balance between the saturation magnetic flux density and low power loss (MHz region); a ferrite core composed of the ferrite composition; and an electronic component having the ferrite core.SOLUTION: There is provided a ferrite composition which mainly comprises: 44.0 to 49.95 mol% of iron oxide in terms of FeO, 1.0 to 20.0 mol% of copper oxide in terms of CuO, 20.0 to 27.9 mol% of zinc oxide in terms of ZnO, 0.01 to 5.4 mol% of manganese oxide in terms of MnOand the balance of nickel oxide, where the ferrite composition contains 2 to 65 ppm of phosphor in terms of P, 40 to 5000 ppm of zirconium oxide in terms of ZrO, 500 to 4000 ppm of tungsten oxide in terms of WOand 10 ppm or less of As in terms of As based on 100 wt.% of the main components and the total content of the iron oxide and the manganese oxide is 50.1 mol% or less in terms of FeOand MnO.

Description

  The present invention relates to a ferrite composition constituting a main part (ferrite part) of an electronic component such as a transformer, a choke coil and an inductor, a ferrite core composed of the composition, and a winding wound around the ferrite core. The present invention relates to an electronic component such as a rotating coil component.

  In recent years, various electronic devices such as portable devices have been rapidly reduced in size and weight, and in response to this, there has been a demand for miniaturization, higher efficiency, and higher frequency of electronic components used in electric circuits of various electronic devices. It is growing rapidly.

  For example, a transformer for a liquid crystal backlight is required to have a smaller and thinner shape and a characteristic equal to or higher than that of a conventional one as the display becomes thinner. The characteristics required for the core used in such a transformer include, for example, low power loss in the operating frequency region and operating temperature region, high initial permeability, high saturation magnetic flux density, and specific resistance. It is expensive. Conventionally, as a core material used in such a transformer, Mn—Zn-based ferrite with low power loss has been used in many cases.

  However, Mn—Zn ferrite has a low specific resistance and cannot be directly wound. Moreover, since the eddy current loss increases as the operating frequency becomes higher, there is a problem that it is not suitable for use in a high frequency region, for example, the MHz region.

  On the other hand, Ni—Zn-based ferrite has higher power loss than the above-mentioned Mn—Zn-based ferrite, but has a high specific resistance and can be directly wound. For this reason, various proposals for reducing the loss of Ni—Zn ferrite have been made.

For example, in Patent Document 1, as a main component, iron oxide is 46.0 to 49.95 mol% in terms of Fe ₂ O ₃ , copper oxide is 2.3 to 12.0 mol% in terms of CuO, and zinc oxide is ZnO. 24.0 to 30.0 mol% in terms of conversion, manganese oxide in an amount of 0.01 to 3.5 mol% in terms of Mn ₂ O ₃ , the balance being composed of nickel oxide, and phosphorus as a subcomponent in terms of P An oxide magnetic material containing 2 to 63 ppm and 0.001 to 0.5 wt% of tungsten oxide in terms of WO ₃ has been proposed.

  However, although the above-mentioned oxide magnetic material improves power loss at 50 kHz, no consideration is given to power loss in a high frequency region, for example, MHz region, and realization of low loss in the high frequency region is desired. It was. In particular, in portable small electronic devices and the like, there is a demand for a ferrite composition having a good balance between high initial magnetic permeability and saturation magnetic flux density and low power loss (MHz region) characteristics.

JP 2003-321272 A

  The present invention has been made in view of such circumstances, and has a high specific resistance, a ferrite composition excellent in the balance between high initial magnetic permeability and saturation magnetic flux density, and low power loss (MHz region), and the ferrite composition An object of the present invention is to provide a ferrite core made of a product and an electronic component having the ferrite core.

In order to achieve the above object, the ferrite composition according to the present invention comprises:
Iron oxide is 44.0 to 49.95 mol% in terms of Fe ₂ O ₃ , copper oxide is 1.0 to 20.0 mol% in terms of CuO, and zinc oxide is 20.0 to 27.9 mol% in terms of ZnO. , manganese oxide containing 0.01 to 5.4 mol% in _Mn 2 _{O 3} in terms of the balance to a ferrite composition comprising a main component composed of nickel oxide,
₂ to 65 ppm in terms of P, zirconium oxide in the range of 40 to 5000 ppm in terms of ZrO ₂ , tungsten oxide in the range of 500 to 4000 ppm in terms of WO ₃ and 10 ppm or less in terms of As with respect to 100% by weight of the main component And
The total content of the iron oxide and the manganese oxide is 50.1 mol% or less in terms of Fe ₂ O ₃ and Mn ₂ O ₃ .

  According to the ferrite composition according to the present invention, the content of the oxide constituting the main component is in the above range, and further, phosphorus, zirconium oxide, tungsten oxide and arsenic are contained in the above range as subcomponents. While maintaining a high initial magnetic permeability (for example, μi is 270 or more) and a high specific resistance, a high saturation magnetic flux density (for example, Bs is 405 mT or more) is obtained, and a figure of merit (μi × Bs) / Pcv of ferrite is desired. (Preferably 3501 or more). Note that the figure of merit (μi × Bs) / Pcv of ferrite is an index representing the good balance of the characteristics of the initial permeability μi, the saturation magnetic flux density Bs, and the power loss Pcv in a high frequency region (for example, 1 MHz or more). .

  In the case of the present invention, the reason why the figure of merit of ferrite improves in the high frequency region is not necessarily clear, but it is necessary that phosphorus, zirconium oxide and tungsten oxide coexist in the above range, and besides the main component and subcomponent. It is considered that the combined effect obtained by controlling the content of arsenic within a predetermined range and the total content of iron oxide and manganese oxide within the above range greatly influences.

  The ferrite core according to the present invention is composed of the above ferrite composition and is used in a frequency region of 1 MHz or more.

  An electronic component according to the present invention is an electronic component having the above ferrite core.

  Although it does not restrict | limit especially as an electronic component which concerns on this invention, A coil component, a transformer component, a magnetic head component, etc. are mentioned. Since the electronic component according to the present invention has a high inductance and a high saturation magnetic flux density, it is suitable as a coil component such as an inductor or a choke coil. It is also suitable for transformer parts such as power transformers for switching and inverters.

  In particular, the ferrite core according to the present invention has a high specific resistance ρ, can maintain a good balance between the initial magnetic permeability μi, the saturation magnetic flux density Bs, and the power loss Pcv, and in a high frequency region (for example, 1 MHz or more). The figure of merit (μi × Bs) / Pcv of ferrite can be set to a desired value (preferably 3501 or more). Such a ferrite core is particularly suitable for use in noise filter parts and inductor parts for EMC that require Z characteristics, such as DC-DC conversion parts for mobile phones and smartphones.

  The upper limit of the frequency to be used is not particularly limited, but is about 20 MHz in consideration of the usage frequency of the device in which the ferrite core or electronic component according to the present invention is used.

  According to the present invention, power loss (core loss) is maintained even in a high frequency region (eg, 1 MHz or more) while maintaining high initial magnetic permeability (eg, μi is 270 or more), saturation magnetic flux density (eg, Bs is 405 mT or more), and specific resistance. ) Is reduced, and a ferrite composition can be obtained in which the figure of merit (μi × Bs) / Pcv of ferrite can be set to a desired value (for example, 3501 or more).

  By applying such a ferrite composition to a ferrite member such as a ferrite core, it is possible to reduce the size, increase the efficiency, and increase the frequency of an electronic component.

  Embodiments of the present invention will be described below.

  Examples of the ferrite core according to the present embodiment include toroidal type, FT type, ET type, EI type, UU type, EE type, EER type, UI type, drum type, pot type, cup type, and the like. A desired transformer is obtained by winding a predetermined number of turns around the ferrite core.

  The ferrite core according to the present embodiment is composed of the ferrite composition according to the present embodiment.

  The ferrite composition according to this embodiment is a Ni—Cu—Zn-based ferrite and contains iron oxide, copper oxide, zinc oxide, manganese oxide, and nickel oxide as main components.

In the main component 100 mol%, the content of iron oxide, calculated as _Fe 2 _{O 3,} 44.0 to 49.95 mol%, preferably 48.1 to 49.8 mol%, more preferably 48.4～ It is 49.6 mol%. Whether the content of iron oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, if the content of iron oxide is too small, power loss (core loss) increases and saturation magnetic flux density tends to decrease.

  In 100 mol% of the main component, the content of copper oxide is 1.0 to 20 mol%, preferably 4.0 to 5.6 mol% in terms of CuO. Whether the content of copper oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, when the content of copper oxide is too large, power loss (core loss) increases and saturation magnetic flux density tends to decrease.

  In 100 mol% of the main component, the content of zinc oxide is 20.0-27.9 mol%, preferably 23.0-27.0 mol% in terms of ZnO. Whether the content of zinc oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, when the content of zinc oxide is too small, the initial permeability tends to decrease, and when it is too large, the power loss (core loss) increases and the saturation magnetic flux density tends to decrease.

In the main component 100 mol%, the content of manganese oxide is a _Mn 2 _{O 3} in terms of, 0.01 to 5.4 mol%, preferably from 0.1 to 1.0 mol%. Whether the content of manganese oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, when the content of manganese oxide is too large, power loss (core loss) increases and initial permeability and saturation magnetic flux density tend to decrease.

Further, in the main component 100 mol%, the total content of iron oxide and manganese oxide _{(Fe 2 O 3 + Mn 2} O 3) is, in terms _{of Fe} 2 _{O 3} and _Mn 2 _{O 3} in terms of 50.1 mol% or less, Preferably it is 49.90 mol% or less. By setting the upper limit of the total content of iron oxide and manganese oxide within the above range, good characteristics can be obtained. In particular, when the total content of iron oxide and manganese oxide (Fe ₂ O ₃ + Mn ₂ O ₃ ) exceeds 50.1 mol% in terms of Fe ₂ O ₃ and Mn ₂ O ₃ , power loss (core loss) , The specific resistance tends to decrease, and the performance index (μi × Bs) / Pcv of the ferrite core in a high frequency region (for example, 1 MHz or more) tends to be lower than a desired value (for example, 3501 or more).

  The remainder of the main component may be composed only of nickel oxide.

  The ferrite composition according to the present embodiment contains phosphorus, zirconium oxide, and tungsten oxide as subcomponents in addition to the above main components.

  The phosphorus content is 2 to 65 ppm, preferably 2 to 30 ppm in terms of P with respect to 100 parts by weight of the main component. Even if the phosphorus content is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). In particular, when the phosphorus content is too large, power loss (core loss) tends to increase.

The content of zirconium oxide is 40 to 5000 ppm, preferably 40 to 1500 ppm in terms of ZrO _{2 with} respect to 100 parts by weight of the main component. Whether the content of zirconium oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, when the content of zirconium oxide is too large, power loss (core loss) tends to increase.

The content of tungsten oxide, relative to 100 parts by weight of the main component, in terms _of WO _3, 500～4000Ppm, preferably 1000-2000 ppm. Whether the content of tungsten oxide is too much or too little, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (eg, 1 MHz or more) tends to be lower than a desired value (eg, 3501 or more). . In particular, when the content of tungsten oxide is too large, power loss (core loss) tends to increase.

  Further, the ferrite composition according to the present embodiment contains arsenic in addition to the main component and the subcomponent. By controlling such components within a predetermined range, high initial permeability (for example, μi is 270 or more) and saturation magnetic flux density (for example, Bs is 405 mT or more) while maintaining power loss (core loss) in a high frequency region. ) And the performance index (μi × Bs) / Pcv of the ferrite core in a high frequency region (for example, 1 MHz or more) can be controlled to a desired value (for example, 3501 or more).

  The content of arsenic is 10 ppm or less, preferably 2 to 5 ppm in terms of As with respect to 100% by weight of the main component. When the arsenic content exceeds 10 ppm in terms of As with respect to 100% by weight of the main component, the saturation magnetic flux density tends to decrease, and the ferrite core figure of merit (μi in a high frequency region (for example, 1 MHz or more)). × Bs) / Pcv tends to be lower than a desired value (for example, 3501 or more).

  In the ferrite composition according to this embodiment, arsenic may be contained in iron oxide, zinc oxide, and manganese oxide, which are main component materials. The inventors of the present application have found that when the arsenic content exceeds a predetermined range, the figure of merit (μi × Bs) / Pcv of the ferrite core in a high frequency region (for example, 1 MHz or more) tends to deteriorate. It was. Therefore, in the present invention, the arsenic content in the raw material is strictly controlled so as to be within the above range. Furthermore, it has been found by the present inventors that the figure of merit in the low magnetic field tends to be good by controlling the arsenic content to 2 to 5 ppm. The method for controlling the arsenic content within a predetermined range is not particularly limited, and may be controlled within a predetermined range by adding an arsenic oxide or the like as a main component.

  In addition, the ferrite composition according to the present embodiment may contain about several ppm to several hundred ppm of inevitable impurity element oxides in the raw material.

  Specifically, B, C, S, Cl, Se, Br, Te, I, Li, Na, Mg, Al, K, Ga, Ge, Sr, In, Sn, Sb, Ba, Pb, Bi, etc. And transition metal elements such as Sc, Ti, V, Cr, Y, Nb, Mo, Pd, Ag, Cd, Hf, and Ta.

  Conventionally, as a ferrite composition suitable as an electronic component such as a portable small electronic device, the power loss Pcv is small even in a high frequency region (for example, 1 MHz or more), and the initial permeability μi, the saturation magnetic flux density Bs, and the ratio A ferrite composition having a high resistance ρ has been demanded.

  However, in the conventional ferrite composition, even if each of the characteristics of the power loss Pcv, the initial magnetic permeability μi, the saturation magnetic flux density Bs, and the specific resistance ρ individually satisfies the predetermined evaluation criteria, When used in specific applications (for example, electronic parts such as DC-DC converted parts used in mobile phones, smartphones, etc.), sufficient performance (for example, core loss, direct current superimposition, inductance, etc.) cannot be obtained. In some cases, defects occurred, and the actual conditions of the evaluation criteria and required characteristics did not match.

  In view of such circumstances, the present inventors have intensively studied and reduced power loss (core loss) and high initial permeability (for example, μi is 270 or more) even in a high frequency region (for example, 1 MHz or more). And by controlling the balance with the saturation magnetic flux density (for example, Bs is 405 mT or more), the present inventors have found a ferrite composition that can be suitably used for a specific application and completed the present invention.

  That is, the present inventors pay attention to the balance between the power loss in the high frequency region (for example, 1 MHz or more) and the initial permeability and the saturation magnetic flux density, and as a new evaluation standard, in the high frequency region (for example, 1 MHz or more). The figure of merit (μi × Bs) / Pcv of the ferrite core was defined.

  In the ferrite composition according to the present embodiment, the performance index (μi × Bs) / Pcv of the ferrite core in a high frequency region (for example, 1 MHz or more) is set to a desired value (for example, 3501 or more). For example, it can be suitably used as an electronic component such as a DC-DC converted component.

  On the other hand, even if the individual characteristics of the power loss Pcv, initial permeability μi, saturation magnetic flux density Bs and specific resistance ρ of the ferrite composition do not satisfy the predetermined evaluation criteria, When the performance index (μi × Bs) / Pcv of the ferrite core at (for example, 1 MHz or more) does not become a desired value (for example, 3501 or more) (that is, the power loss Pcv, the initial permeability μi, and the saturation magnetic flux density Bs are unbalanced) In some cases, problems such as inability to obtain sufficient performance (for example, core loss, DC superimposition, inductance, etc.) may occur.

  Next, an example of a method for producing a ferrite composition according to this embodiment will be described.

  First, starting materials (raw materials of main components and raw materials of subcomponents) are weighed and mixed so as to have a predetermined composition ratio to obtain a raw material mixture. Examples of the mixing method include wet mixing using a ball mill and dry mixing using a dry mixer. It is preferable to use a starting material having an average particle size of 0.1 to 3 μm.

Examples of the main component material include iron oxide (α-Fe ₂ O ₃ ), copper oxide (CuO), zinc oxide (ZnO), nickel oxide (NiO), manganese oxide (Mn ₂ O ₃ ), and composite oxides. Can be used. In addition, various compounds that become oxides or composite oxides by firing can be used. Examples of the oxide that becomes the above-described oxide upon firing include simple metals, carbonates, oxalates, nitrates, hydroxides, halides, organometallic compounds, and the like.

Phosphorus (P), zirconium oxide (ZrO ₂ ), or tungsten oxide (WO ₃ ) can be used as a raw material for the accessory component. Phosphorus is preferably used in the form of phosphoric acid (P ₂ O ₅ ). Zirconium oxide and tungsten oxide may be the same as those of the main component material.

  Arsenic may be contained in iron oxide, zinc oxide, and manganese oxide, which are raw materials of the main component. Therefore, the content of arsenic can be adjusted by adjusting the amount of various iron oxide, zinc oxide and manganese oxide raw materials having different arsenic contents. The method for controlling the arsenic content within a predetermined range is not particularly limited, and may be controlled within a predetermined range by adding an arsenic oxide or the like as a main component.

  Next, the raw material mixture is calcined to obtain a calcined material. Calcining causes thermal decomposition of raw materials, homogenization of ingredients, formation of ferrite, disappearance of ultrafine powder due to sintering and grain growth to an appropriate particle size, and converts the raw material mixture into a form suitable for the subsequent process. Done for. Such calcination is preferably performed at a temperature of 800 to 1100 ° C. for about 1 to 3 hours. The calcination may be performed in the air (air), or may be performed in an atmosphere having a higher oxygen partial pressure or in a pure oxygen atmosphere than in the air. The mixing of the main component raw material and the subcomponent raw material may be performed before calcining or after calcining.

  Next, the calcined material is pulverized to obtain a pulverized material. The pulverization is performed in order to break down the coagulation of the calcined material to obtain a powder having appropriate sinterability. When the calcined material forms a large lump, wet pulverization is performed using a ball mill or an attritor after coarse pulverization. The wet pulverization is performed until the average particle diameter of the calcined material is preferably about 1 to 2 μm.

  Next, the pulverized material is granulated (granular) to obtain a granulated product. The granulation is performed in order to convert the pulverized material into aggregated particles having an appropriate size and convert it into a form suitable for molding. Examples of such a granulation method include a pressure granulation method and a spray drying method. The spray drying method is a method in which a commonly used binder such as polyvinyl alcohol is added to the pulverized material, and then atomized in a spray dryer and dried at a low temperature.

  Next, the granulated product is molded into a predetermined shape to obtain a molded body. Examples of the molding of the granulated product include dry molding, wet molding, and extrusion molding. The dry molding method is a molding method in which a granulated product is filled in a mold and compressed and pressed (pressed). The shape of the molded body is not particularly limited, and may be appropriately determined according to the application. In the present embodiment, the shape is a toroidal shape.

  Next, the compact is fired to obtain a sintered body (the ferrite composition of the present embodiment). This firing is performed in order to obtain a dense sintered body by causing sintering in which the powder adheres at a temperature below the melting point between the powder particles of the molded body containing many voids. Such firing is preferably performed at a temperature of 900 to 1300 ° C. for usually 2 to 5 hours. The main calcination may be performed in the atmosphere (air) or in an atmosphere having a higher oxygen partial pressure than in the atmosphere.

  Through such steps, the ferrite composition according to the present embodiment is manufactured.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  For example, in the above-described embodiment, in order to obtain a toroidal shape, the shape is formed before the main firing, but the shape may be formed (processed) after the main firing.

  In the above-described embodiment, the ferrite composition according to this embodiment is used as a ferrite core, but is not particularly limited, and is also suitable as a ferrite part of a coil component such as a magnetic head component, an inductor, or a choke coil. Can be used. Moreover, you may comprise the ferrite part of transformer components, such as power supply transformers for switching, an inverter, etc. with the ferrite composition of this invention.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

First, Fe ₂ O ₃ , NiO, CuO, ZnO, and Mn ₂ O ₃ were prepared as main component materials. P ₂ O ₅ , ZrO _2, and WO ₃ were prepared as subcomponent raw materials. The average particle size of the starting material was 0.1 to 3 μm.

  Arsenic is contained in iron oxide, zinc oxide, and manganese oxide, which are raw materials of the main component. Therefore, it prepared by adjusting the usage-amounts of various iron oxides, zinc oxides, and manganese oxide raw materials from which arsenic content differs so that the sample finally obtained may contain As amount of Table 1-4. .

  Next, the prepared raw material powders of the main component and subcomponent were weighed and then wet mixed by a ball mill for 5 hours to obtain a raw material mixture.

  Next, the obtained raw material mixture was calcined in air at 900 ° C. for 2 hours to obtain a calcined material, and then wet pulverized with a ball mill for 20 hours to obtain a pulverized material.

  Next, after drying this pulverized material, 1.0 part by weight of polyvinyl alcohol as a binder was added to 100 parts by weight of the pulverized material, granulated, and sized with a 20 mesh sieve to obtain granules. The granules are pressure-molded at a pressure of 100 kPa to form a toroidal shaped body (dimension = outer diameter 18 mm × inner diameter 10 mm × height 5 mm) and a disk shape (dimension = diameter 25 mm × thickness 5 mm). Got.

  Next, each of these molded bodies was fired in air at 1000 to 1250 ° C. for 2 hours to obtain a toroidal core sample and a disk core sample as a sintered body. The obtained sample was subjected to fluorescent X-ray analysis to measure the composition of the ferrite core. The results are shown in Tables 1-4. The phosphorus (P) content was measured by absorptiometry. Furthermore, the following characteristics evaluation was performed with respect to the sample.

Specific resistance (ρ)
An In—Ga electrode was applied to both surfaces of the obtained disk core sample, a direct current resistance value was measured, and a specific resistance ρ was determined (unit: Ωm). The measurement was performed using an IR meter (SUPER MEGOHMMETERMODEL SM-5E manufactured by TOA Electronics). ρ was determined to be 10 ⁸ Ωm or more. The results are shown in Tables 1-4.

Power loss (Pcv)
A primary winding and a secondary winding were wound five times on the obtained toroidal core sample, and power loss Pcv at 1 MHz, 10 mT, and 23 ° C. was measured (unit: kW / m ³ ). The measurement was performed using a BH analyzer (SY-8232 manufactured by Iwasaki Tsushinki Co., Ltd.). Pcv at 1 MHz was determined to be 60 kW / m ³ or less. The results are shown in Tables 1-4.

  In addition, since a ferrite core and an electronic component having a use frequency of 1 MHz or more are applied to, for example, a DC-DC conversion component used for a mobile phone, a smartphone, or the like, in the present embodiment, such a device is usually used. Pcv was measured in the temperature region and the magnetic field region.

Initial permeability (μi)
A copper wire was wound around the obtained toroidal core sample for 10 turns, and an initial magnetic permeability μi was measured using an LCR meter (Hewlett Packard 4284A). The measurement conditions were a measurement frequency of 100 kHz, a measurement temperature of 23 ° C., and a measurement level of 0.4 A / m. The μi at 100 kHz was considered good at 270 or more. The results are shown in Tables 1-4.

Saturation magnetic flux density (Bs)
After winding the winding 60 times on the obtained toroidal core sample, the saturation magnetic flux density Bs when a magnetic field of 4 kA / m was applied using a BH curve tracer (Model BHS40 manufactured by Riken Denshi Co., Ltd.) Measurement was performed at 23 ° C. (unit: mT). Bs made 405 mT or more favorable. The results are shown in Tables 1-4.

  Tables 1 to 4 also show (μi × Bs) / Pcv indicating the performance index of the ferrite core at 1 MHz. (Μi × Bs) / Pcv was determined to be 3501 or more. More preferably, it is 5000 or more.

  In addition, a high initial permeability (for example, μi is 270 or more) and a saturation magnetic flux density (for example, Bs is 405 mT or more), and a ferrite core figure of merit (μi × Bs) / Pcv at 1 MHz is obtained as described above. By setting the value (for example, 3501 or more), it can be suitably used as an electronic component such as a DC-DC conversion component used in, for example, a mobile phone or a smartphone.

From Tables 1 to 4, subcomponents P, ZrO ₂ and WO ₃ are simultaneously contained in a content within the scope of the present invention, and the arsenic content is within the scope of the present invention, and the main composition is contained. When the amount is within the range of the present invention (Examples 1 to 38), the specific resistance ρ is sufficiently high, the power loss Pcv is good at 1 MHz, and the high initial permeability (for example, μi is 270 or more). And a saturation magnetic flux density (for example, Bs is 405 mT or more), and it has been confirmed that the figure of merit (μi × Bs) / Pcv of the ferrite core at 1 MHz is a desired value (for example, 3501 or more) as described above. .

On the other hand, from Table 1, when P and / or ZrO ₂ is not contained, or when the content of P or ZrO ₂ is outside the scope of the present invention (Comparative Examples 1 to 7) It was confirmed that the figure of merit (μi × Bs) / Pcv of the ferrite core at 1 MHz does not become a desired value (for example, 3501 or more).

  Further, from Table 2, when the content of CuO or ZnO falls outside the scope of the present invention (Comparative Examples 8 to 11), the figure of merit (μi × Bs) / Pcv of the ferrite core at 1 MHz is a desired value ( For example, it was confirmed that it was not 3501 or more.

Furthermore, from Table 3, when the content of Fe ₂ O ₃ is outside the scope of the present invention, when the content of Mn ₂ O ₃ is outside the scope of the present invention, or Fe ₂ O ₃ and Mn ₂ O ₃ When the total amount is outside the range of the present invention (Comparative Examples 12 to 17), it is confirmed that the performance index (μi × Bs) / Pcv of the ferrite core at 1 MHz does not become a desired value (for example, 3501 or more). It was done. Furthermore, when the total amount of Fe ₂ O ₃ and Mn ₂ O ₃ was outside the range of the present invention (Comparative Examples 16 and 17), it was confirmed that the specific resistance ρ was particularly deteriorated.

Furthermore, from Table 4, when the content of As and / or WO ₃ is outside the scope of the present invention (Comparative Examples 18 to 21), the ferrite core figure of merit (μi × Bs) / Pcv at 1 MHz. Is not a desired value (for example, 3501 or more). Further, when As is 2 to 5 ppm (Examples 1, 32 and 33), the ferrite core at 1 MHz is compared with the case where As is less than 1 ppm (Example 31) and 10 ppm (Example 34). It was confirmed that the figure of merit (μi × Bs) / Pcv was high.

Claims (3)

Iron oxide is 44.0 to 49.95 mol% in terms of Fe ₂ O ₃ , copper oxide is 1.0 to 20.0 mol% in terms of CuO, and zinc oxide is 20.0 to 27.9 mol% in terms of ZnO. , manganese oxide containing 0.01 to 5.4 mol% in _Mn 2 _{O 3} in terms of the balance to a ferrite composition comprising a main component composed of nickel oxide,
₂ to 65 ppm in terms of P, zirconium oxide in the range of 40 to 5000 ppm in terms of ZrO ₂ , tungsten oxide in the range of 500 to 4000 ppm in terms of WO ₃ and 10 ppm or less in terms of As with respect to 100% by weight of the main component. ,
The ferrite composition, wherein the total content of the iron oxide and the manganese oxide is 50.1 mol% or less in terms of Fe ₂ O ₃ and Mn ₂ O ₃ .   A ferrite core composed of the ferrite composition according to claim 1 and used in a frequency region of 1 MHz or more. An electronic component having the ferrite core according to claim 2.