JP6051930B2 - Ferrite composition, ferrite core and electronic component - Google Patents

Description

  In particular, the present invention relates to a ferrite composition that constitutes a main part (ferrite part) of a coil component used in an electronic pen or the like, a ferrite core composed of the composition, and a winding around the ferrite core. The present invention relates to an electronic component such as a coil component.

  In recent years, various electronic devices such as portable devices have been rapidly reduced in size and weight, and in order to cope with this, demands for miniaturization, higher efficiency and higher frequency of electronic components used in electric circuits of various electronic devices 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 permeability, high saturation magnetic flux density, and high specific resistance. Can be mentioned. 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, in the core for electronic pens, the operating frequency region is approximately 500 to 700 kHz, and improvement in sensitivity in the frequency region is required. The characteristics required for such an electronic pen core include, for example, a high Q value in the use frequency region and use temperature region, and a small change in inductance value (L value) with respect to temperature. It is done.

  Here, although the above-described oxide magnetic material has improved power loss at 50 kHz, in a frequency range of 500 to 700 kHz that is a use frequency region of the electronic pen core, a high Q value, and an inductance value ( The change in (L value) is not small.

JP 2003-321272 A

  The present invention has been made in view of such a situation, and has a high Q value at 500 to 700 kHz, and has a small change in L value with respect to temperature, and provides a ferrite composition suitable for use in an electronic pen. Objective.

In order to achieve the above object, the ferrite composition according to the present invention comprises:
The main components are 47.0 to 49.95 mol% of iron oxide in terms of Fe ₂ O ₃ , 1.0 to 12.0 mol% of copper oxide in terms of CuO, and 28.0 to 35 in terms of zinc oxide. 0.0 mol%, manganese oxide containing 0.01 to 2.4 mol% in terms of Mn ₂ O ₃ , the balance being composed of nickel oxide, and as an accessory component with respect to 100 parts by weight of the main component ₂ to 65 ppm in terms of phosphorus, 40 to 4500 ppm in terms of zirconium oxide in terms of ZrO ₂ , 50 to 2500 ppm in terms of cobalt oxide in terms of CoO, and an As content of 10 ppm or less,
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 .

  By setting the content of the oxide constituting the main component in the above range, and further containing phosphorus, zirconium oxide and cobalt oxide in the above range as subcomponents, and suppressing the content of As below the above amount, According to the ferrite composition of the present invention, the figure of merit (μ × Q) / (ΔL / L) of ferrite in the frequency region of 500 to 700 kHz can be increased. Note that the figure of merit (μ × Q) / (ΔL / L) of ferrite is an index representing the small change of the L value with respect to the temperature and the sensitivity of the electronic pen when the ferrite is used for the electronic pen. is there. The larger the figure of merit, the less the change of the L value with respect to the temperature, the larger the permeability μ and the Q value, and the higher the performance of the electronic pen when the ferrite composition is used for a ferrite core for an electronic pen. Here, ΔL is the amount of change of the L value with respect to the temperature change of the ferrite.

  In the case of the present invention, the reason why the figure of merit of ferrite improves in the frequency range of 500 to 700 kHz is not necessarily clear, but phosphorus and zirconium oxide coexist in a predetermined range, and the content of cobalt oxide is in a predetermined range. It is considered that the combined effect obtained by controlling the content of As to below the predetermined amount or making the total content of iron oxide and manganese oxide within the above range greatly influences. .

  The ferrite core according to the present invention is preferably composed of the ferrite composition described in any of the above, and is used in a frequency range of 500 to 700 kHz.

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

  Although it does not restrict | limit especially as an electronic component which concerns on this invention, Especially the coil components for electronic pens are mentioned.

  In particular, the ferrite core according to the present invention has a high specific resistance ρ, a high Q value, and a high magnetic permeability μ, and a desired figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz. This can be done. Such a ferrite core is particularly suitable for use in an electronic pen core.

  According to the present invention, a ferrite composition capable of making the figure of merit (μ × Q) / (ΔL / L) of a ferrite to be a desired value or more while maintaining a high Q value, magnetic permeability, and specific resistance at 500 to 700 kHz. Can be obtained.

  By applying such a ferrite composition to the ferrite member of the core for an electronic pen, it is possible to achieve high sensitivity of the coil component for the electronic pen and high performance of the electronic pen.

FIG. 1 shows an elongate toroidal core for an electronic pen. FIG. 2 shows an electronic pen core in which an elongated cylindrical core and a shorter cylindrical core are combined.

  The present invention will be described below with reference to embodiments shown in the drawings.

  An example of the ferrite core according to the present embodiment is the elongated toroidal ferrite core shown in FIG. A desired electronic pen coil component is obtained by winding a predetermined number of windings around the ferrite core.

  Moreover, as another ferrite core which concerns on this embodiment, the elongate cylindrical ferrite core shown in FIG. 2 and the short cylindrical ferrite core can be illustrated. A desired number of coil parts for an electronic pen are obtained by winding a predetermined number of windings around an elongated cylindrical core and holding the interval between ferrite cores variable.

  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 ferrite core 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,} 47.0 to 49.95 mol%, preferably 47.0 to 49.6 mol%, more preferably 48.4～ 49.4 mol%. If the content of iron oxide is too much, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease. When the content of iron oxide is too small, the magnetic permeability μ tends to decrease.

  In 100 mol% of the main component, the content of copper oxide is 1.0 to 12.0 mol%, preferably 4.0 to 12.0 mol% in terms of CuO. If the content of copper oxide is too much or too little, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease.

  In 100 mol% of the main component, the content of zinc oxide is 28.0 to 35.0 mol%, preferably 29.0 to 34.0 mol%, more preferably 29.0 to 32.0 in terms of ZnO. Mol%. If the content of zinc oxide is too much or too little, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz 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 2.4 mol%, preferably from 0.1 to 1.3 mol%. When the content of manganese oxide is too large, the ferrite figure of merit (μ × Q) / (ΔL / L) tends to decrease at 500 to 700 kHz. When the content of manganese oxide is too small, the magnetic permeability μ at 500 to 700 kHz tends to decrease.

Further, in 100 mol% of the main component, the total content of iron oxide and manganese oxide (50.1 mol% or less, preferably 49.90 mol% or less in terms of Fe ₂ O ₃ and Mn ₂ O ₃ ). Good characteristics can be obtained by setting the upper limit of the total content of iron oxide and manganese oxide within the above range, in particular, 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 , the specific resistance ρ tends to decrease, and the figure of merit (μ × Q) of ferrite at 500 to 700 kHz / (ΔL / L) tends to decrease.

  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 cobalt oxide as subcomponents in addition to the above main components.

  The phosphorus content is 2 to 65 ppm, preferably 7 to 30 ppm in terms of P with respect to 100 parts by weight of the main component. If the content of phosphorus is too much or too little, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease.

The content of zirconium oxide is 40 to 4500 ppm, preferably 110 to 1500 ppm in terms of ZrO _{2 with} respect to 100% by weight of the main component. Even if the content of zirconium oxide is too much or too little, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease.

  The content of cobalt oxide is 50 to 2500 ppm, preferably 100 to 2500 ppm in terms of CoO with respect to 100% by weight of the main component. If the content of cobalt oxide is too much or too little, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease.

  The ferrite composition according to this embodiment has an As content of 10 ppm or less, preferably 2 to 5 ppm, in addition to the main component and subcomponents. When the content of As is too large, the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz tends to decrease.

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

  In the ferrite composition according to the present embodiment, the ferrite figure of merit (μ × Q) / (ΔL / L) in a frequency region of 500 to 700 kHz is preferably used as an electronic pen core by setting it to a desired value or more. be able to.

  On the other hand, the individual characteristics of the ferrite composition Q value, ΔL / L value, permeability μ and specific resistance ρ in the frequency range of 500 to 700 kHz are satisfied as well as not satisfying the predetermined evaluation criteria. However, when the figure of merit (μ × Q) / (ΔL / L) of ferrite in the frequency region of 500 to 700 kHz is less than a desired value (that is, the permeability, Q value, and ΔL / L value are poorly balanced). In some cases, there may be problems such as insufficient sensitivity when used in an electronic pen core.

  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.

As raw materials of the main component, iron oxide (α-Fe ₂ O ₃ ), copper oxide (CuO), zinc oxide (ZnO), nickel oxide (NiO), manganese oxide (Mn ₂ O ₃ ) as required, or A composite oxide or the like 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.

As a raw material of the subcomponent, phosphorus (P), zirconium oxide (ZrO ₂ ), cobalt oxide (CoO), and As can be used. Phosphorus is preferably used in the form of phosphoric acid (P ₂ O ₅ ). Zirconium oxide and cobalt oxide may be the same as those of the main component material. As may be the same as that of the main component material, or may be contained as an impurity in the main component material such as iron oxide, zinc oxide, and manganese oxide. In this case, the As content can be controlled by adjusting the amount of raw materials such as various iron oxides having different As contents.

  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.

  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, it can implement with a various aspect in the range which does not deviate from the summary of this invention. .

  For example, in the above-described embodiment, in order to obtain a toroidal shape or a cylindrical 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 for electronic pens, but the application of the ferrite composition according to this embodiment is not limited to the ferrite core for electronic pens. , (Μ × Q) / (ΔL / L) is preferably used as a ferrite part such as an antenna core for an RFID system.

  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 , CoO and arsenic oxide were prepared as the raw materials for the accessory components. The average particle size of the starting material was 0.1 to 3 μm.

  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. This granule is pressure-molded at a pressure of 100 kPa to form a toroidal shaped (dimension = outer diameter 18 mm, inner diameter 10 mm, height 5 mm) and disk shape (dimension = outer diameter 18 mm, height 5 mm). Got the body.

  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.

Permeability (μ)
A copper wire was wound around the obtained toroidal core sample for 10 turns, and an initial transmittance μ was measured using an LCR meter (Hewlett Packard 4284A). The measurement conditions were a measurement frequency of 500 kHz, a measurement temperature of 23 ° C., and a measurement level of 0.4 A / m. At 500 kHz, μ was 500 or more. The results are shown in Tables 1-4.

ΔL / L (20 ° C-60 ° C)
The obtained toroidal core sample is wound with a copper wire wire for 10 turns, and an inductance value (L value) at 20 ° C. and 60 ° C. is measured using a thermostatic bath and an LCR meter (Hewlett Packard 4284A). Was ΔL. L was measured at 23 ° C. and ΔL / L was calculated. Other measurement conditions were a measurement frequency of 500 kHz and a measurement level of 0.4 A / m. The results are shown in Tables 1-4.

Q
A copper wire was wound around the obtained toroidal core sample for 3 turns, and Q was measured using an LCR meter (Hewlett Packard 4284A). The measurement conditions were a measurement frequency of 500 kHz, a measurement temperature of 23 ° C., and a measurement level of 0.4 A / m. The Q at 500 kHz was determined to be 44 or more. The results are shown in Tables 1-4.

  Tables 1 to 4 also show the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 kHz. (Μ × Q) / (ΔL / L) was 1700 or more.

  In addition, by setting the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 to 700 kHz to 1700 or more, it can be suitably used as a ferrite composition for electronic parts such as coil parts for electronic pens.

From Tables 1 to 4, when the subcomponents P, ZrO ₂ and CoO are contained at the same time, the As content is within the scope of the present invention, and the main component content is within the scope of the present invention. (Examples 1 to 38), the specific resistance ρ is sufficiently high, and high magnetic permeability μ and Q value are obtained at 500 kHz, and the ferrite figure of merit (μ × Q) / (ΔL / L) is 1700 or more. It was confirmed that

On the other hand, from Table 1, when one or more of P, ZrO ₂ or CoO is not contained, or when the content of P or ZrO ₂ is outside the scope of the present invention (comparison) Examples 1 to 7) It was confirmed that the figure of merit (μ × Q) / (ΔL / L) of ferrite at 500 kHz was not 1700 or more.

  Further, from Table 2, when the contents of CuO and ZnO are outside the scope of the present invention (Comparative Examples 8 to 11), the ferrite figure of merit (μ × Q) / (ΔL / L) at 1 500 is 1700. It was confirmed that this was not the case.

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, the figure of merit (μ × Q) / (ΔL / L) of the ferrite core at 500 kHz does not become 1700 or more (Comparative Examples 12, 14, 16, 17). Alternatively, it was confirmed that μ was not 500 or more (Comparative Examples 13 and 15). Further, if the _Fe 2 _{O 3} is too large, or _Fe 2 _{O 3} and _Mn 2 when the total amount of _{O 3} is outside the scope of the present invention (Comparative Examples 12, 16, 17), in particular the specific resistance ρ It was confirmed that it deteriorated.

  Furthermore, from Table 4, when CoO or As is outside the scope of the present invention (Comparative Examples 18 to 21), it was confirmed that the performance index of the ferrite core at 500 kHz does not become 1700 or more.

Claims (3)

The main components are 47.0 to 49.95 mol% of iron oxide in terms of Fe ₂ O ₃ , 1.0 to 12.0 mol% of copper oxide in terms of CuO, and 28.0 to 35 in terms of zinc oxide. 0.0 mol%, manganese oxide containing 0.01 to 2.4 mol% in terms of Mn ₂ O ₃ , the balance being composed of nickel oxide, and as an accessory component with respect to 100 parts by weight of the main component ₂ to 65 ppm in terms of phosphorus, 40 to 4500 ppm in terms of zirconium oxide in terms of ZrO ₂ , 50 to 2500 ppm in terms of cobalt oxide in terms of CoO, and As is 10 ppm or less,
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 500 to 700 kHz.   An electronic component having the ferrite core according to claim 2.

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