JP5582279B2 - Inductance element comprising Ni-Zn-Cu ferrite sintered body - Google Patents

Description

  The present invention relates to an inductance element using a Ni—Zn—Cu ferrite material having excellent direct current superposition characteristics.

  In recent years, electronic devices such as portable devices and information devices have been required to be rapidly downsized and highly functional, and components such as inductance elements used in these devices are also required to be downsized and highly functional. Has been. In particular, an inductance element used in a power supply circuit is required to have a reduction in inductance and an increase in core loss as much as possible as a DC superimposition characteristic when an alternating current and a direct current are passed.

  Conventionally, an inductance element uses Mn—Zn ferrite or Ni—Zn ferrite as a material, and structurally provides a magnetic gap to improve DC superposition characteristics and adjust the ferrite composition. The core loss was reduced by adding additives.

  In particular, multilayer inductance elements are manufactured by laminating a ferrite material and a nonmagnetic material, which is a magnetic gap, and firing them at the same time, so the adhesion between them, the difference in shrinkage during firing, the difference in thermal expansion coefficient Therefore, there is a problem that it is difficult to obtain desired characteristics.

  In order to solve this problem, the development of a ferrite material having excellent DC superposition characteristics in the magnetic material itself without structurally providing a magnetic gap has been promoted, and Ni-Zn doped with silicon oxide and zircon oxide is added. Ni-Zn-Cu ferrite (Patent Document 1 and Patent Document 2) and silicon-added Ni-Zn-Cu ferrite (Patent Document 3) are known.

On the other hand, a technique (Patent Document 4 and Patent Document 5) for controlling a change in inductance caused by a stress change by incorporating Zn ₂ SiO ₄ into a Ni—Zn—Cu-based ferrite has been proposed.

JP 2003-112968 A JP 2004-172396 A JP 2005-145781 A JP-A-2-137301 JP 2004-296865 A

  In the aforementioned Patent Documents 1 to 3, by adding silicon oxide and zircon oxide to Ni—Zn or Ni—Zn—Cu ferrite, it is possible to suppress a decrease in magnetic permeability when DC current is superimposed. It is shown. However, no consideration is given to the core loss, and it is difficult to apply the ferrite material to the magnetic material itself having excellent DC superposition characteristics.

  In the aforementioned Patent Documents 4 and 5, a technique for controlling a change in inductance caused by a stress change is described, but the DC superimposition characteristic is not considered, and the magnetic material itself has an excellent DC superimposition characteristic. It is difficult to apply the ferrite material.

  Accordingly, an object of the present invention is to provide an inductance element having excellent direct current superposition characteristics using a ferrite material in which the magnetic material itself has excellent direct current superposition characteristics.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention comprises a Ni—Zn—Cu ferrite sintered body obtained by firing a mixture of spinel ferrite and zinc silicate at 880 to 1050 ° C., and comprises spinel ferrite and zinc silicate. a inductance element consisting including Ni-Zn-Cu ferrite sintered body, the composition of the Ni-Zn-Cu ferrite sintered body, in terms of oxide, 36.0～48.5Mol% of Fe ₂ O _{3, 7.0~38mol%} of NiO, 4.5~40mol% of ZnO, 5.0~17mol% of CuO, consists of SiO ₂ 1.0~8.0mol%, the spinel ferrite 311 A ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the plane is 0.005 to 0.065. An inductance element characterized by comprising (present invention 1).

Further, according to the present invention, in the Ni—Zn—Cu ferrite sintered body constituting the inductance element according to the first aspect of the present invention, the sintered density is 4.9 to 5.25 g / cm ³ , and a DC superimposed magnetic field is applied. The real part μ ₀ ′ of the magnetic permeability measured in a state where the magnetic field is not measured is 20 to 170, the core loss P ₀ is 100 to 1400 kW / m ³ , and the magnetic permeability measured in a state where a DC superposition magnetic field of 1000 A / m is applied. The ratio μ ₁₀₀₀ ′ / μ ₀ ′ of the real part μ ₁₀₀₀ ′ to μ ₀ ′ is 0.5 to 1.0, and the core losses P ₁₀₀₀ and P ₀ measured with a DC superposition magnetic field of 1000 A / m applied An inductance element having a ratio P ₁₀₀₀ / P ₀ of 0.7 to 2.0 (Invention 2).

  Further, the present invention provides an inductance element made of the Ni—Zn—Cu ferrite sintered body according to the first or second aspect of the present invention, wherein the inductance measured in a state where a DC superimposed current flows is not flowing a DC superimposed current. The inductance element has a DC superposition current of 55 to 2600 mA when the measured inductance becomes 90% (Invention 3).

  The inductance element according to the present invention is suitable as an inductance element for a DC power line because it has excellent direct current superposition characteristics.

  The configuration of the present invention will be described in more detail as follows.

In the present invention, as an index of the DC superposition characteristics of the ferrite material, the real part μ ₀ ′ of the permeability measured without applying the DC superposition magnetic field and the permeability measured with the DC superposition magnetic field of 1000 A / m applied. The ratio μ ₁₀₀₀ ′ / μ ₀ ′ with the real part μ ₁₀₀₀ ′ was used. This ratio μ ₁₀₀₀ ′ / μ ₀ ′ indicates the degree of decrease in magnetic permeability when the DC superimposed magnetic field is 1000 A / m with reference to the permeability when the DC superimposed magnetic field is 0 A / m. This value is usually 1 or less, but as this value is closer to 1, it means that the real part of the magnetic permeability is less likely to decrease when a DC superimposed magnetic field is applied. Indicates that the direct current superposition characteristics are excellent.

Furthermore, in the present invention, as an index of the DC superposition characteristics of the ferrite material, the core loss P ₀ measured with no DC superposition magnetic field applied and the core loss P ₁₀₀₀ measured with the DC superposition magnetic field 1000 A / m applied, The ratio P ₁₀₀₀ / P ₀ was used. This ratio P ₁₀₀₀ / P ₀ indicates the degree of change in the core loss when the DC superimposed magnetic field is 1000 A / m with reference to the core loss when the DC superimposed magnetic field is 0 A / m. When this value is greater than 1, it indicates that the core loss increases when a DC superimposed magnetic field is applied.

Furthermore, in the present invention, as an index of the DC superposition characteristic of the inductance element, 90% of the inductance L ₀ measured in the state where the DC superposition current is not passed is measured when the DC superposition current is passed at the frequency of 2 MHz. The DC superimposed current I ₉₀ when It can be said that the larger the I ₉₀ , the larger the DC superimposed current can flow without causing a decrease in inductance, and the DC superimposed characteristic is excellent.

  The inductance element according to the present invention will be described.

The inductance L _{0 of the} inductance element according to the present invention is preferably 0.4 to 55 μH. More preferably, it is 0.5-50 microH. When the inductance L ₀ is less than 0.4, the value is small and it is difficult to use it in an electronic circuit. In the method of the present invention, an inductance element exceeding 55 μH cannot be obtained.

In the inductance element according to the present invention, the DC superimposed current I ₉₀ is 55 to 2600 mA when the inductance in a state where the DC superimposed current flows is 90% of L ₀ . Preferably, it is 60-2400 mA. More preferably, it is 65-2300 mA.

  Next, a method for manufacturing an inductance element according to the present invention will be described.

  In the inductance element according to the present invention, a Ni—Zn—Cu ferrite powder having a characteristic composition is manufactured, then a green sheet is manufactured using the Ni—Zn—Cu ferrite powder, and the obtained green sheet is obtained. An inductance element can be obtained by forming a laminated body using the sintered body and sintering the laminated body at a predetermined temperature.

  First, the Ni—Zn—Cu ferrite powder in the present invention will be described.

The Ni—Zn—Cu ferrite powder in the present invention is a Ni—Zn—Cu ferrite powder composed of spinel ferrite and zinc silicate, and 36.0 to 48.5 mol% Fe ₂ O in terms of oxide. _3, it has 7.0～38Mol% of NiO, 4.5~40mol% of ZnO, 5.0~17mol% of CuO, a composition composed of SiO ₂ of 1.0～8.0Mol%, the Ni- In X-ray diffraction of Zn—Cu ferrite powder, the ratio of the X-ray diffraction intensity of the 113 plane of zinc silicate to the X-ray diffraction intensity of the 311 plane of the spinel ferrite (113 plane of zinc silicate / 311 of spinel ferrite) Surface) is 0.01 to 0.12.

When the composition of Fe ₂ O ₃ is outside the above range, the sinterability of the ferrite powder is poor and the sintered density is low. The composition of Fe ₂ O ₃ is preferably 36.0 to 48.0 mol%, more preferably 37.0 to 47.5 mol%.

When the composition of NiO is less than 7.0 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small when the ferrite powder is used as a sintered body, and the direct current superimposition characteristics are deteriorated. When the composition of NiO exceeds 38 mol%, μ ₀ ′ becomes small when the ferrite powder is used as a sintered body, so that it is difficult to obtain a large inductance value when an inductance element is used. A preferable composition of NiO is 7.0 to 37 mol%, more preferably 8.0 to 37 mol%.

When the composition of ZnO is less than 4.5 mol%, μ ₀ ′ becomes small when the ferrite powder is used as a sintered body, so that it is difficult to obtain a large inductance value when an inductance element is used. When the composition of ZnO exceeds 40 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small when the ferrite powder is used as a sintered body, and the direct current superimposition characteristic is deteriorated. A preferable composition of ZnO is 5.0 to 39 mol%.

  When the composition of CuO is less than 5.0 mol%, the sinterability of the ferrite powder is poor and the sintered density is low. When the composition of CuO exceeds 17 mol%, the sintered body is likely to be deformed, and it becomes difficult to obtain a sintered body having a desired shape. A preferable composition of CuO is 6.0 to 17 mol%, more preferably 6.0 to 16 mol%.

When the composition of SiO ₂ is less than 1.0 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small when the ferrite powder is used as a sintered body, and the direct current superimposition characteristic is deteriorated. When the composition of SiO ₂ exceeds 8.0 mol%, the sinterability of the ferrite powder is poor and the sintered density is lowered. A preferable composition of SiO ₂ is 1.0 to 7.0 mol%.

The composition of the Ni—Zn—Cu ferrite powder in the present invention is such that Fe ₂ O ₃ is 36 to 48 mol%, NiO is 7.0 to 25.5 mol%, ZnO is 16 to 36 mol%, and CuO is 7.0 to 17 mol%. % And SiO _{2 in} the range of 1.0 to 8.0 mol%, sintering at 950 ° C. or lower, so-called low temperature sintering is possible. A circuit can be easily formed inside the assembly.

When the ratio of the X-ray diffraction intensity of 113 of zinc silicate to the X-ray diffraction intensity of the 311 surface of spinel ferrite is less than 0.01, the Ni-Zn-Cu ferrite powder in the present invention is When the sintered body is used, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small, and the direct current superimposition characteristics deteriorate. When the ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of the spinel ferrite exceeds 0.120, the sinterability of the ferrite powder is poor and the sintering density Becomes lower. The ratio of the X-ray diffraction intensity of the 113 plane of zinc silicate to the X-ray diffraction intensity of the 311 plane of spinel ferrite is preferably 0.01 to 0.115.

  The ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of the spinel ferrite (113 plane of zinc silicate / 311 plane of the spinel ferrite) is 0.01 to 0.12. For example, there is a method of adding 2 to 15 wt% of zinc silicate as described later to a ferrite powder prepared in advance.

The composition of the zinc silicate, ZnO is a 55~70mol% SiO ₂ is in the range of 30～45Mol% preferred. If it is outside this range, the sinterability of the ferrite powder may be poor and the sintered density may be lowered. A more preferable composition of zinc silicate is that ZnO is 60 to 67 mol% and SiO ₂ is 33 to 40 mol%. The stoichiometric composition of zinc silicate is 66.7 mol% for ZnO and 33.3 mol% for SiO _{2. By} shifting the composition from this, ZnO or SiO ₂ is mixed in zinc silicate. May be.

  The average particle size of zinc silicate is preferably 0.1 to 30 μm. When the average particle size is out of the above range, the ferrite powder may have poor sinterability and the sintered density may be lowered. A preferable average particle diameter is 0.2 to 20 μm.

The BET specific surface area of the Ni—Zn—Cu ferrite powder in the present invention is preferably 4 to 12 m ² / g. When the BET specific surface area is less than 4 m ² / g, the sinterability of the ferrite powder is poor and the sintered density is low. When the BET specific surface area exceeds 12 m ² / g, the ferrite powder cannot be uniformly dispersed in the solvent in the green sheet manufacturing process described later. A preferred BET specific surface area is 6 to 11 m ² / g.

  The Ni—Zn—Cu based ferrite powder in the present invention is a raw material mixture obtained by mixing raw materials such as oxides, carbonates, hydroxides, oxalates and the like of each element constituting the ferrite by a conventional method. After calcining in the temperature range of 650 to 900 ° C. for 1 to 20 hours in the air, the calcined product added with zinc silicate prepared by the following method can be pulverized. Alternatively, it can be obtained by mixing the zinc silicate produced by the following method after pulverizing the calcined product alone.

  In the present invention, zinc silicate is obtained by mixing a raw material mixture obtained by mixing raw materials such as silicon and zinc oxides, carbonates, hydroxides, and oxalates in the temperature range of 1000 to 1300 ° C. It can be obtained by firing for 1 to 20 hours.

  Next, the green sheet in the present invention will be described.

  The green sheet is a paint by mixing the Ni-Zn-Cu ferrite powder with a binder, a plasticizer, a solvent, and the like, and the paint is formed to a thickness of several μm to several hundred μm with a doctor blade type coater or the like. The sheet is formed after being formed and then dried.

  The green sheet in the present invention contains 2 to 20 parts by weight of the binder and 0.5 to 15 parts by weight of the plasticizer with respect to 100 parts by weight of the Ni—Zn—Cu ferrite powder in the present invention. Preferably, the binder contains 4 to 15 parts by weight and the plasticizer contains 1 to 10 parts by weight. Further, the solvent may remain due to insufficient drying after film formation. Furthermore, you may add well-known additives, such as a viscosity modifier, as needed.

  Examples of the binding material include polyvinyl butyral, polyacrylic acid ester, polymethyl methacrylate, vinyl chloride, polymethacrylic acid ester, ethylene cellulose, abietic acid resin, and the like. A preferred binding material is polyvinyl butyral.

  When the binding material is less than 2 parts by weight, the green sheet becomes brittle, and in order to have strength, a content exceeding 20 parts by weight is not necessary.

  Examples of the plasticizer include benzyl-n-butyl phthalate, butyl butyl phthalyl glycolate, dibutyl phthalate, dimethyl phthalate, polyethylene glycol, phthalate ester, butyl stearate, and methyl agitate.

  When the plasticizer is less than 0.5 parts by weight, the green sheet becomes hard and cracks are likely to occur. When the plasticizer exceeds 15 parts by weight, the green sheet becomes soft and difficult to handle.

  In the production of the green sheet in the present invention, 15 to 150 parts by weight of the solvent is used with respect to 100 parts by weight of the Ni—Zn—Cu ferrite powder. When the solvent is out of the above range, a uniform green sheet cannot be obtained. Therefore, the inductance element obtained by sintering the sheet tends to vary in characteristics.

  The kind of solvent is acetone, benzene, butanol, ethanol, methyl ethyl ketone, toluene, propyl alcohol, isopropyl alcohol, n-butyl acetate, 3methyl-3methoxy-1 butanol, and the like.

The lamination pressure is preferably 0.2 × 10 ^{4 to} 0.6 × 10 ⁴ t / m ² .

  Next, the Ni—Zn—Cu ferrite sintered body in the present invention will be described.

The Ni—Zn—Cu ferrite sintered body in the present invention is a Ni—Zn—Cu ferrite sintered body composed of spinel ferrite and zinc silicate, and is 36 to 48.5 mol% Fe in terms of oxide. Spinel having a composition comprising ₂ O ₃ , 7.0-38 mol% NiO, 4.5-40 mol% ZnO, 5.0-17 mol% CuO, 1.0-8.0 mol% SiO ₂ The ratio of the X-ray diffraction intensity of the 113 plane of zinc silicate to the X-ray diffraction intensity of the 311 plane of the type ferrite (113 plane of zinc silicate / 311 plane of spinel type ferrite) is 0.005 to 0.065.

When the composition of Fe ₂ O ₃ is out of the above range, the sintered density is lowered. A preferable composition of Fe ₂ O ₃ is 37 to 47.5 mol%.

When the composition of NiO is less than 7 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small and the direct current superimposition characteristic is deteriorated. When the composition of NiO exceeds 38 mol%, μ ₀ ′ becomes small, so that it is difficult to obtain a large inductance value when an inductance element is used. A preferred NiO composition is 8.0 to 37 mol%.

When the composition of ZnO is less than 4.5 mol%, μ ₀ ′ is small, and it is difficult to obtain a large inductance value when an inductance element is used. When the composition of ZnO exceeds 40 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small and the direct current superimposition characteristic is deteriorated. A preferable composition of ZnO is 5.0 to 39 mol%.

  When the composition of CuO is less than 5.0 mol%, the sintered density becomes low. When the composition of CuO exceeds 17 mol%, the sintered body is likely to be deformed, and it becomes difficult to obtain a sintered body having a desired shape. A preferable composition of CuO is 6.0 to 16 mol%.

When the composition of SiO ₂ is less than 1.0 mol%, μ ₁₀₀₀ ′ / μ ₀ ′ becomes small and the direct current superimposition characteristic is deteriorated. When the composition of SiO ₂ exceeds 8.0 mol%, the sintered density becomes low. A preferable composition of SiO ₂ is 1.0 to 7.0 mol%.

The composition of the Ni—Zn—Cu ferrite sintered body in the present invention is such that Fe ₂ O ₃ is 36 to 48 mol%, NiO is 7.0 to 25.5 mol%, ZnO is 16 to 36 mol%, and CuO is 7.0. When ˜17 mol% and SiO ₂ are in the range of 1.0 to 8.0 mol%, sintering at 950 ° C. or lower, so-called low temperature sintering is possible. A circuit can be easily formed inside the sintered body.

In the Ni—Zn—Cu ferrite sintered body in the present invention, when the ratio of the X-ray diffraction intensity of the 113 plane of zinc silicate to the X-ray diffraction intensity of the 311 plane of the spinel ferrite is less than 0.005, μ ₁₀₀₀ ′ / μ ₀ ′ becomes smaller, and the DC superimposition characteristic becomes worse. When the ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of the spinel ferrite exceeds 0.065, the sintered density becomes low. The ratio of the X-ray diffraction intensity of the 113 plane of zinc silicate to the X-ray diffraction intensity of the 311 plane of spinel ferrite is preferably 0.005 to 0.060.

The sintered density of the Ni—Zn—Cu ferrite sintered body in the present invention is 4.9 to 5.25 g / cm ³ . When the sintered density is less than 4.9 g / cm ³ , the sintered body has low mechanical strength and may be damaged during use. The higher the sintered density, the better, but the upper limit of the sintered density obtained in the present invention is 5.25 g / cm ³ . A preferable sintered density is 4.95 to 5.2 g / cm ³ .

The real part μ ₀ ′ of the magnetic permeability of the Ni—Zn—Cu ferrite sintered body in the present invention is 20 to 170. When the real part μ ₀ ′ of the magnetic permeability is less than 20, it is difficult to obtain a large inductance value when an inductance element is used. When the real part μ ₀ ′ of the magnetic permeability exceeds 170, the direct current superimposition characteristics deteriorate. The real part μ ₀ ′ of preferable magnetic permeability is 30 to 160.

The μ ₁₀₀₀ ′ / μ ₀ ′ of the Ni—Zn—Cu ferrite sintered body in the present invention is 0.5 or more. When μ ₁₀₀₀ ′ / μ ₀ ′ is less than 0.5, only an inductance element having inferior DC superimposition characteristics can be obtained. The upper limit is 1.0.

The core loss P ₀ of the Ni—Zn—Cu ferrite sintered body in the present invention is 1400 kW / m ³ or less. When the core loss P ₀ exceeds 1400 kW / m ³ , the loss as a sintered body increases, so that only inefficient inductance elements can be obtained. The core loss P ₀ is preferably 1300 kW / m ³ or less, more preferably 1200 kW / m ³ or less, and even more preferably 1000 kW / m ³ or less. The lower limit is about 100 kW / m ³ .

_P 1000 / _{P 0} of the Ni-Zn-Cu-based ferrite sintered body of the present invention is 0.7 to 2.0. If it is out of this range, the direct current superimposition characteristic is deteriorated. P ₁₀₀₀ / P ₀ is preferably 0.8 to 1.9.

The Ni—Zn—Cu based ferrite sintered body in the present invention is obtained by using the Ni—Zn—Cu based ferrite powder in the present invention at a pressure of 0.3 to 3.0 × 10 ⁴ t / m ² using a mold. Obtained by a so-called green sheet method obtained by laminating green sheets containing Ni-Zn-Cu ferrite powder in the present invention, or a molded body obtained by so-called powder pressure molding method. The obtained laminate can be obtained by sintering at 880 to 1050 ° C. for 1 to 20 hours, preferably 1 to 10 hours. As a molding method, a known method can be used, but the above-mentioned powder pressure molding method and the green sheet method are preferable.

  When the sintering temperature is lower than 880 ° C., the sintered density is lowered, so that the mechanical strength of the sintered body is lowered. When the sintering temperature exceeds 1050 ° C., the sintered body is likely to be deformed, making it difficult to obtain a sintered body having a desired shape.

  In the inductance element according to the present invention, first, a winding wiring is formed with a conductive paste on the green sheet obtained above, and these are laminated and pressed, and then cut into a predetermined size. Thereafter, the obtained laminate can be obtained by sintering at 880 to 1050 ° C. for 1 to 20 hours, preferably 1 to 10 hours.

  The type of the conductive paste can be appropriately selected according to the sintering temperature. For example, Ag paste can be used at about 900 ° C., and noble metal-containing Ag paste or noble metal paste can be used at around 1000 ° C.

  When the sintering temperature is lower than 880 ° C., the sintered density is lowered, so that the mechanical strength of the sintered body is lowered. When the sintering temperature exceeds 1050 ° C., the sintered body is likely to be deformed, making it difficult to obtain a sintered body having a desired shape.

<Action>
The most important point in the present invention is the sintering of Ni—Zn—Cu ferrite powder comprising spinel ferrite and zinc silicate, and Fe ₂ O ₃ , NiO, ZnO, CuO and SiO ₂ in a specific composition range. The Ni—Zn—Cu ferrite sintered body obtained in this way is the fact that the magnetic material itself has excellent direct current superposition characteristics. The reason why the direct current superimposition characteristic is improved is not yet clear, but the presence of zinc silicate at the grain boundary of Ni-Zn-Cu ferrite having a specific ferrite composition range causes Ni-Zn-Cu ferrite sintering. The inventor presumes that the magnetization curve of the body is caused by a linear change with a gentle inclination.

  Further, the inductance element using the Ni—Zn—Cu ferrite sintered body exhibits excellent DC superposition characteristics without providing a magnetic gap. This is presumed to be because leakage magnetic flux can be reduced because there is no magnetic gap.

  A typical embodiment of the present invention is as follows.

  The compositions of the Ni—Zn—Cu ferrite powder and the Ni—Zn—Cu ferrite sintered body were measured using a fluorescent X-ray analyzer RIX2100 (manufactured by Rigaku Corporation).

  The ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of the spinel type ferrite and the crystal phase constituting the Ni—Zn—Cu ferrite powder and the sintered body is X-ray Measurement was performed using a diffractometer RINT2500 (manufactured by Rigaku Corporation).

  The sintered density of the Ni—Zn—Cu ferrite sintered body was calculated from the volume and weight determined from the outer diameter of the sample.

The magnetic permeability μ ₀ ′ of the Ni—Zn—Cu ferrite sintered body is determined by applying a winding to the ring-shaped sintered body, setting the frequency to 1 MHz, the magnetic flux density to 25 mT, and applying B—H in a state where no DC superimposed magnetic field is applied. / Z analyzer E5060A (manufactured by Agilent Technologies) was used as the value of the real part of the magnetic permeability.

The permeability μ ₁₀₀₀ ′ of the Ni—Zn—Cu ferrite sintered body is determined by applying a winding to the ring-shaped sintered body, applying a frequency of 1 MHz, a magnetic flux density of 25 mT, and applying a DC superimposed magnetic field of 1000 A / m. -It was set as the value of the real part of the magnetic permeability measured using H / Z analyzer E5060A (manufactured by Agilent Technologies). μ ₁₀₀₀ ′ / μ ₀ ′ was obtained by calculation from μ ₀ ′ and μ ₁₀₀₀ ′.

The core loss P ₀ of the Ni—Zn—Cu ferrite sintered body is obtained by applying a winding to the ring-shaped sintered body, setting the frequency to 1 MHz, the magnetic flux density to 25 mT, and applying BH / and the value of _{P cv} measured using Z analyzer E5060A (manufactured by Agilent technologies Inc.).

The core loss _{P 1000} of the Ni-Zn-Cu ferrite sintered body is subjected to winding to the ring-shaped sintered body, 1MHz frequency, the magnetic flux density 25 mT, the DC bias magnetic field while applying 1000A / m B- and the value of _{P cv} measured using the H / Z analyzer E5060A (manufactured by Agilent technologies Inc.). _{P 1000} / P ₀ was calculated from _{P 0} and _{P 1000.}

The inductance of the inductance element was evaluated by an inductance L ₀ measured using an E4991A RF impedance / material analyzer (manufactured by Agilent Technologies) with no DC superimposed current flowing at a frequency of 2 MHz. In addition, the DC superposition characteristics of the inductance were evaluated by the DC superposition current I ₉₀ when the inductance became 90% of L ₀ when a DC superposition current was passed at a frequency of 2 MHz with the same measuring device. In these measurements, the alternating current of E4991A was set to 2 mA.

Example 1
<Production of Ni-Zn-Cu ferrite powder>
Each oxide raw material is weighed so that the composition of the Ni-Zn-Cu ferrite becomes a predetermined composition, wet mixed using a ball mill for 20 hours, and then the mixed slurry is filtered and dried to mix the raw materials. A powder was obtained. The calcined product obtained by calcining the raw material mixed powder at 720 ° C. for 4 hours was pulverized with an atomizer to obtain a pulverized ferrite powder.

On the other hand, zinc oxide and silicon oxide were weighed so that the composition of zinc silicate was a predetermined composition, and wet mixed using a ball mill for 20 hours. The mixed slurry was filtered and dried, and then calcined at 1200 ° C. for 3 hours to obtain zinc silicate. The composition of the obtained zinc silicate was ZnO = 66.5 mol%, SiO ₂ = 33.5 mol%, and the average particle diameter was 5.2 μm.

  Next, the zinc silicate was added to the ferrite pulverized powder so as to have a predetermined composition, and mixed and pulverized with a ball mill to obtain the Ni—Zn—Cu ferrite powder in the present invention.

The composition of the obtained Ni—Zn—Cu ferrite powder was Fe ₂ O ₃ = 47.5 mol%, NiO = 14.0 mol%, ZnO = 27.0 mol%, CuO = 10.5 mol% and SiO ₂ = 1. 0.0 mol%. The ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of spinel ferrite was 0.010. The BET specific surface area was 8.8 m ² / g.

<Manufacture of green sheets>
8 parts by weight of polyvinyl butyral as a binding material, 3 parts by weight of benzyl-n-butyl phthalate as a plasticizer, and 3 methyl-3methoxy-1-butanol as a solvent with respect to 100 parts by weight of the obtained Ni—Zn—Cu ferrite powder After adding 50 parts by weight, the mixture was mixed well to obtain a slurry. This slurry was applied onto a PET film by a doctor blade type coater to form a coating film, and then dried to obtain a green sheet having a thickness of 45 μm. This was cut into a size of 100 mm in length and 100 mm in width, and 12 sheets were laminated, and then pressed with a pressure of 0.35 × 10 ⁴ t / m ² to obtain a green sheet laminate having a thickness of 0.53 mm. It was.

<Production of Ni-Zn-Cu ferrite sintered body>
The obtained green sheet laminate was sintered at 890 ° C. for 2 hours to obtain a Ni—Zn—Cu ferrite sintered body having a thickness of 0.44 mm.
The composition of the obtained Ni—Zn—Cu-based ferrite sintered body was as follows: Fe ₂ O ₃ = 47.5 mol%, NiO = 14.2 mol%, ZnO = 27.1 mol%, CuO = 10.2 mol% and SiO ₂ = 1.0 mol%. In the Ni—Zn—Cu ferrite sintered body, the ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of spinel ferrite was 0.005. The sintered density was 5.01 g / cm ³ .
Further, a ring-shaped sintered body having an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 0.48 mm was cut out from the Ni—Zn—Cu ferrite sintered body by an ultrasonic machine, and the magnetic properties were evaluated. The sintered body had a μ ₀ ′ of 152, a μ ₁₀₀₀ ′ / μ ₀ ′ of 0.50, a core loss P ₀ of 380 kW / m ³ , and a P ₁₀₀₀ / P ₀ of 1.88.

<Manufacture of inductance elements>
The green sheet obtained by the above-described method was cut into a size of 160 mm long × 160 mm wide, through holes were opened and filled with Ag paste, and then the winding wire of the inductor was printed with a thickness of 20 μm with Ag paste. After laminating the green sheets in such an order that the inductor wiring enters from one end of the piece, rolls out and then exits from the other end, 0.35 × 10 ⁴ t / m ² A green sheet laminate having a thickness of 1.2 mm was obtained by applying pressure. At this time, the total number of stacked green sheets was 27, and the winding wiring was 15.5 turns. The obtained green sheet laminate was cut into a size of 2.4 mm in length × 1.9 mm in width, sintered at 890 ° C. for 2 hours, and an inductance element of 2 mm in length × 1.6 mm in width × 1 mm in height. Got. The inductance L ₀ of the obtained inductance element was 55.2 μH, and I ₉₀ was 86 mA.

Example 2 to Example 7
In the same manner as in Example 1, a Ni—Zn—Cu ferrite sintered body was obtained. Tables 1, 2, and 3 show the manufacturing conditions and the characteristics of the obtained Ni—Zn—Cu ferrite sintered body. Further, an inductance element was manufactured in the same manner as in Example 1. Table 4 shows the manufacturing conditions and various characteristics of the obtained inductance element.

Example 8
A Ni—Zn—Cu ferrite powder similar to that in Example 1 was prepared, and a mixed powder obtained by mixing 10 parts by weight of a 6% aqueous polyvinyl alcohol solution with 100 parts by weight of the Ni—Zn—Cu ferrite powder. 7.0 g was molded into a disk shape having an outer diameter of 30 mm and a thickness of 2.9 mm using a mold at a molding pressure of 1.0 × 10 ⁴ t / m ² . This molded body was sintered at a sintering temperature of 900 ° C. for 5 hours to obtain a Ni—Zn—Cu ferrite sintered body.

  After measuring the composition, X-ray diffraction intensity ratio, and sintering density of the obtained Ni—Zn—Cu ferrite sintered body, ring sintering with an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 2 mm was performed using an ultrasonic machine. The body was cut out and evaluated for magnetic properties.

  Tables 1, 2, and 3 show the manufacturing conditions and the characteristics of the obtained Ni—Zn—Cu ferrite sintered body.

  Further, an inductance element was manufactured through a green sheet in the same manner as in Example 1. Table 4 shows the manufacturing conditions and the characteristics of the obtained inductance element.

Example 9 to Example 10
In the same manner as in Example 8, a Ni—Zn—Cu ferrite sintered body was obtained. Tables 1, 2, and 3 show the manufacturing conditions and the characteristics of the obtained Ni—Zn—Cu ferrite sintered body.

  Further, an inductance element was manufactured through a green sheet in the same manner as in Example 1. Table 4 shows the manufacturing conditions and the characteristics of the obtained inductance element.

Comparative Examples 1 to 3
A Ni—Zn-Cu ferrite sintered body was obtained in the same manner as in Example 1. Tables 1, 2, and 3 show the manufacturing conditions and the characteristics of the obtained Ni—Zn—Cu ferrite sintered body.

Comparative Example 4 to Comparative Example 5
In the same manner as in Example 8, a Ni—Zn—Cu ferrite sintered body was obtained. Tables 1, 2, and 3 show the manufacturing conditions and the characteristics of the obtained Ni—Zn—Cu ferrite sintered body.

  Further, an inductance element was manufactured through a green sheet in the same manner as in Example 1. Table 4 shows the manufacturing conditions and the characteristics of the obtained inductance element.

Comparative Example 6
Each oxide raw material was weighed so that the composition of the ferrite was Fe ₂ O ₃ = 49.5 mol%, NiO = 20.7 mol%, ZnO = 22.8 mol%, CuO = 7 mol%, and 20 using a ball mill. After wet mixing for a period of time, the mixed slurry was filtered and dried to obtain a raw material mixed powder. The calcined product obtained by calcining the raw material mixed powder at 750 ° C. for 4 hours was pulverized with an atomizer to obtain a pulverized ferrite powder.

On the other hand, zinc oxide and silicon oxide were weighed so that the composition of zinc silicate was Zn ₂ SiO ₄ and wet mixed for 20 hours using a ball mill. The mixed slurry was filtered and dried, and then calcined at 1200 ° C. for 3 hours to obtain zinc silicate. The composition of the obtained zinc silicate was ZnO = 66.7 mol%, SiO ₂ = 33.3 mol%, and the average particle diameter was 5.0 μm.

  Next, 1.5 wt% of the zinc silicate was added to the ferrite pulverized powder, and mixed and pulverized with a ball mill to obtain the Ni—Zn—Cu ferrite powder in the present invention.

The composition of the obtained Ni—Zn—Cu based ferrite powder is as follows: Fe ₂ O ₃ = 48.4 mol%, NiO = 20.4 mol%, ZnO = 23.6 mol%, CuO = 6.8 mol% and SiO ₂ = 0. 0.8 mol%. The ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of spinel ferrite was 0.006. The BET specific surface area was 7.5 m ² / g.

7.0 × 10 ⁴ t of 7.0 g of a mixed powder obtained by mixing 10 parts by weight of a 6% aqueous solution of polyvinyl alcohol with 100 parts by weight of the obtained Ni—Zn—Cu ferrite powder using a mold. It was molded into a disk shape having an outer diameter of 30 mm and a thickness of 2.9 mm with a molding pressure of / m ² . This molded body was sintered at a sintering temperature of 1000 ° C. for 2 hours to obtain a Ni—Zn—Cu ferrite sintered body.

The composition of the obtained Ni—Zn—Cu ferrite sintered body was as follows: Fe ₂ O ₃ = 48.5 mol%, NiO = 20.5 mol%, ZnO = 23.3 mol%, CuO = 6.9 mol% and SiO _2. = 0.8 mol%. The ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the X-ray diffraction intensity from the 311 plane of the spinel ferrite in the Ni—Zn—Cu ferrite sintered body was 0.003. The sintered density was 5.19 g / cm ³ . Furthermore, a ring-shaped sintered body having an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 2 mm was cut out from the Ni—Zn—Cu ferrite sintered body with an ultrasonic machine, and the magnetic properties were evaluated. The sintered body had a μ ₀ ′ of 242, a μ ₁₀₀₀ ′ / μ ₀ ′ of 0.28, a core loss P ₀ of 198 kW / m ³ , and a P ₁₀₀₀ / P ₀ of 2.97.

  In Comparative Example 6, since the amount of zinc silicate added to the spinel ferrite is small, the X of the 113 plane of zinc silicate with respect to the X-ray diffraction intensity of the 311 plane of the spinel ferrite in the Ni—Zn—Cu ferrite powder. The ratio of the line diffraction intensity became small, and the sintered body prepared using the Ni—Zn—Cu ferrite powder was hardly said to have excellent DC superposition characteristics.

  Further, an inductance element was manufactured through a green sheet in the same manner as in Example 1. Table 4 shows the manufacturing conditions and the characteristics of the obtained inductance element.

As is apparent from the above examples, the Ni—Zn—Cu ferrite sintered body composed of spinel ferrite and zinc silicate, which is 36 to 48.5 mol% Fe ₂ O ₃ and 7 to 38 mol in terms of oxide. Zinc silicate with respect to the X-ray diffraction intensity from the 311 plane of spinel-type ferrite having a composition consisting of 1% NiO, 4.5 to 40 mol% ZnO, 5 to 17 mol% CuO, and 1 to 8 mol% SiO ₂ An inductance element made of a Ni—Zn—Cu ferrite sintered body having a ratio of X-ray diffraction intensity from the 113 plane of 0.005 to 0.065 has excellent direct current superposition characteristics. It is suitable as.

An inductance element using the Ni—Zn—Cu ferrite sintered body exhibits excellent direct current superposition characteristics, and is therefore suitable as an inductance element for a DC power line.

Claims (3)

It consists spinel ferrite and zinc silicate and mixture 880-1050 firing-obtained Ni-Zn-Cu ferrite sintered body ℃ of, including a spinel ferrite and zinc silicate Ni-Zn- a inductance element consisting of Cu ferrite sintered body, the composition of the Ni-Zn-Cu ferrite sintered body, in terms of oxide, 36.0～48.5Mol% of _Fe 2 _O 3, 7. X-ray diffraction from 311 plane of spinel type ferrite consisting of 0-38 mol% NiO, 4.5-40 mol% ZnO, 5.0-17 mol% CuO, 1.0-8.0 mol% SiO ₂ A ratio of the X-ray diffraction intensity from the 113 plane of zinc silicate to the strength is 0.005 to 0.065, and is characterized by comprising a Ni—Zn—Cu ferrite sintered body characterized by Inductance element. The Ni—Zn—Cu ferrite sintered body constituting the inductance element according to claim 1, wherein the sintered density is 4.9 to 5.25 g / cm ³ , and the permeability is measured without applying a DC superimposed magnetic field. The real part μ ₀ ′ of the magnetic permeability is 20 to 170, the core loss P ₀ is 100 to 1400 kW / m ³ , and the real part of the magnetic permeability μ ₁₀₀₀ ′ measured with a DC superimposed magnetic field of 1000 A / m applied, mu ₀ 'ratio _{μ 1000'} / _{μ 0} 'is is 0.5-1.0, the ratio _P 1000 / _{P 0} of the core loss _{P 1000} and _{P 0} measured in a state in which a DC bias magnetic field was applied 1000A / m Is an inductance element of 0.7 to 2.0. The inductance element comprising the Ni-Zn-Cu ferrite sintered body according to claim 1 or 2, wherein the inductance measured in a state where a DC superimposed current is passed is 90% of the inductance measured in a state where no DC superimposed current is passed. An inductance element having a DC superposition current of 55 to 2600 mA.