JP2007269503A - Ni-Cu-Zn BASED FERRITE MATERIAL AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Ni-Cu-Zn based ferrite material capable of exhibiting the effect of SnO<SB>2</SB>addition at a maximum. <P>SOLUTION: The Ni-Cu-Zn based ferrite material comprises a sintered compact having a composition of main ingredients of 45-49.8 mol% Fe<SB>2</SB>O<SB>3</SB>, <10 mol% CuO, 10-40 mol% ZnO and the balance NiO, contains 0.2-4 wt.% SnO<SB>2</SB>as an auxiliary ingredient to the main ingredients wherein and the variation coefficient CV of Sn is ≥0.2%. It is preferable that the Ni-Cu-Zn based ferrite material contains 0.5-3 wt.% SnO<SB>2</SB>as the auxiliary ingredient to the main ingredients and has 0.25-0.5% variation coefficient CV of Sn and further CuO in the main ingredients is 1-5 mol%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Ni—Cu—Zn based ferrite material, and more particularly to a Ni—Cu—Zn based ferrite material in which a change in inductance L with respect to an external stress is small and a change in inductance L with respect to a temperature change is small.

  Ni-Cu-Zn ferrite materials are used as inductors, transformers, and noise removal cores, and are widely used in mobile devices such as mobile phones and notebook computers. However, when a stress such as a compressive stress is applied to the ferrite material, the inductance L (or magnetic permeability μ) changes and the magnetic characteristics tend to deteriorate. For this reason, when a stress is applied to a product using a ferrite material, there is a problem that the magnetic characteristics change and the characteristics of the product fluctuate. Therefore, it is necessary to obtain a Ni—Cu—Zn-based ferrite material with little change in inductance L (or permeability μ) even when an external stress is applied. Such stability of characteristics against external stress is sometimes referred to as anti-stress characteristics.

  In addition, since portable devices such as mobile phones and notebook computers are used in various environments, the components incorporated in the devices need to be highly resistant to the environment. In particular, resistance to temperature changes is important. Since the temperature changes greatly depending on the season and the place where it is used, a Ni—Cu—Zn ferrite material having a stable inductance L (or magnetic permeability μ) against the temperature change is required.

Regarding this problem, Patent Document 1 (Japanese Patent Laid-Open No. 2003-272912) discloses that the main component composition of the Ni—Cu—Zn-based ferrite material is Fe ₂ O ₃ : 45 to 50 mol%, ZnO: 1 to 32 mol%, Even when a compressive stress of 40 MPa is applied, CuO is 5 to 15 mol%, NiO is the balance, and 0.2 to 3 wt% of SnO ₂ is added to the total composition ratio of the main component composition. It discloses that the rate of change of magnetic susceptibility is suppressed to within ± 10%, and good DC superposition characteristics can be obtained.
Patent Document 2 (Japanese Patent Laid-Open No. 2004-172396) corresponds to the L value of an inductance element by simultaneously adding a specific amount of ZrO ₂ or SiO ₂ to a Ni—Zn-based or Ni—Cu—Zn-based ferrite material. It is disclosed that in the permeability of the ferrite material, the change at the time of direct current superposition becomes small, there is no change in the structure of the element, and the element can be reduced in size and height. Further, it is said that it is effective to add 0.1 to 1.0 wt% of SnO ₂ for improving temperature characteristics.

Patent Document 3 (Japanese Patent No. 314796) discloses Fe ₂ O ₃ , CuO, ZnO, and NiO, Fe ₂ O ₃ : 46.5 to 49.5 mol%, CuO: 5.0 to 12.0 mol. %, ZnO: 2.0 to 30.0 mol%, NiO: Ni—Cu—Zn-based ferrite material containing in the ratio of the balance Co ₃ O ₄ , Bi ₂ O ₃ , SiO ₂ , and SnO ₂ The content ratio is Co ₃ O ₄ : 0.05 to 0.60 wt%, Bi ₂ O ₃ : 0.50 to 2.00 wt%, and the total amount of SiO ₂ and SnO ₂ : 0.10 to ₂ When blended at a ratio of 0.000% by weight (except when either SiO ₂ or SnO ₂ is 0% by weight), the change in inductance L due to stress such as shrinkage during resin mold processing Disclosure of what can be made smaller To have.
Further, Patent Document 4 (Japanese Patent Application Laid-Open No. 2002-124408) discloses that a Ni—Cu—Zn based ferrite material having a predetermined molar ratio contains SnO ₂ in an amount of 0.4 to 3.0 wt% alone, or Li ₂ CO _3. It is disclosed that by adding 0.3 to 0.5 wt%, a multilayer inductor or the like with little fluctuation in characteristics with respect to external stress can be obtained.

JP 2003-272912 A JP 2004-172396 A Japanese Patent No. 314796 JP 2002-124408 A

As described above, it is well known that the addition of SnO ₂ to a Ni—Cu—Zn-based ferrite material is effective in improving the anti-stress characteristics and further improving the temperature characteristics. However, it is desired to further improve the anti-stress characteristics and further the temperature characteristics. Therefore, the present invention aims to provide a Ni—Cu—Zn-based ferrite material in which the effect of adding SnO ₂ is maximized. To do. Moreover, an object of this invention is to provide the manufacturing method of such a Ni-Cu-Zn type ferrite material.

Usually, the Ni—Cu—Zn based ferrite material is manufactured through a process of mixing and crushing raw materials, calcining, crushing, forming and firing. And it was thought that in order to obtain a high characteristic, each raw material component should be more uniformly dispersed before forming. For example, the same applies to Sn compounds based on the addition of SnO _2, which is one of the raw materials, and it is recognized that it is necessary to uniformly disperse the other raw materials Fe ₂ O ₃ , CuO, ZnO and NiO. It was. This can also be seen from the fact that, in Patent Document 1, etc., SnO ₂ is mixed and pulverized together with Fe ₂ O ₃ , CuO, ZnO and NiO which are other raw materials, and calcined. Incidentally, the addition of SnO ₂ as a raw material, the presence form after sintering is a place unclear, for convenience, may also be referred to as SnO ₂ in the sintered body.
However, according to the study by the present inventors, as is clear from the examples described later, in the sintered body of Ni—Cu—Zn based ferrite, the segregation of SnO ₂ has higher antistress characteristics and temperature characteristics. The surprising result was good. The present invention is based on this new knowledge, the composition of the main _{component, Fe 2 O 3: 45~49.8mol%} , CuO: less than 10mol%, ZnO: 10~40mol%, NiO: in balance It consists of a certain sintered body, and this sintered body contains 0.2 to 4 wt% of SnO ₂ with respect to the main component as a subcomponent, and the coefficient of variation CV of Sn is 0.2% or more. Ni-Cu-Zn ferrite material.
In the Ni—Cu—Zn-based ferrite material of the present invention, 0.5 to 3 wt% of SnO ₂ is contained as a subcomponent with respect to the main component, and the Sn variation coefficient CV is 0.25 to 0.5%. It is preferable. Furthermore, it is preferable for this invention that CuO of a main component is 1-5 mol%.

In order to obtain the Ni—Zn—Cu based ferrite material according to the present invention as described above, it is necessary to devise in manufacturing. In this, the addition of the SnO ₂ raw material is performed after calcining the raw material constituting the main component. Are listed as effective means. When calcining together with the raw materials constituting the main component, the dispersion state of SnO ₂ tends to be uniform. Therefore, the main component is calcined to avoid this, and then the SnO ₂ raw material is added. That is, the present invention includes a step of calcining a raw material mixture of main components having a composition of Fe ₂ O ₃ : 45 to 49.8 mol%, CuO: less than 10 mol%, ZnO: 10 to 40 mol%, NiO: the balance, A step of adding 0.2 to 4 wt% of SnO ₂ raw material powder to the reaction product obtained by baking, mixing and pulverizing with the reaction product, and pressing the obtained pulverized product to obtain a molded body There is provided a method for producing a Ni-Cu-Zn-based ferrite material, comprising a step and a step of firing a molded body to form a sintered body.

According to Ni-Cu-Zn ferrite material of the present invention, by controlling the dispersion state in the sintered body of SnO _2, it can be drawn to improve the effect of anti-stress properties and temperature characteristics of SnO ₂ added enough . In addition, according to the method for producing the Ni—Cu—Zn ferrite material of the present invention, the Ni—Cu—Zn ferrite having improved anti-stress characteristics and temperature characteristics by intentionally controlling the dispersion state of SnO _2. Material can be provided.

The Ni—Cu—Zn based ferrite material according to the present invention is characterized in that the coefficient of variation CV (Coefficient of Variance) of Sn is 0.2% or more. Here, the coefficient of variation CV is a value obtained by dividing the standard deviation by the average. The coefficient of variation CV of Sn in the present invention is obtained by elemental mapping of Sn with EPMA (Electron Probe Micro Analyzer) under the conditions shown in the examples described later, and the standard deviation of the Sn concentration at all analysis points is represented by the Sn of all analysis points. The value obtained by dividing by the average value of density. The lower this value, the better the dispersibility of Sn, and the higher this value, the worse the Sn dispersibility. In addition, although the object of element mapping is Sn, this Sn exists as a Sn compound, for example, SnO _{2 in the} sintered body.

  The Ni—Cu—Zn based ferrite material of the present invention can improve the anti-stress characteristics. Here, the anti-stress characteristic in the present invention refers to the degree of change in the inductance L of the Ni—Cu—Zn-based ferrite material with respect to compressive stress. In a resin mold type inductance element, a Ni—Cu—Zn based ferrite material is resin molded, but compressive stress is applied to the Ni—Cu—Zn based ferrite material when the resin is cured. Since the inductance L of Ni—Cu—Zn-based ferrite material changes depending on the magnitude of compressive stress, the resin mold type inductance element has little change in inductance L with respect to compressive stress, and has excellent anti-stress characteristics. -Cu-Zn ferrite material is desired.

In the present invention, with respect to the anti-stress characteristic, the target is to set the change rate ΔL of the inductance L before and after the application of uniaxial compressive stress of 1 ton / cm ² (98 MPa) to ± 7% or less. The change rate ΔL of the inductance L is preferably ± 5% or less, and more preferably ± 3% or less. The change rate ΔL of the inductance L is measured by continuously measuring the inductance L at this time by winding a wire 30 times around a prism sample used in the examples described later and applying a uniaxial compressive stress to the sample at a constant speed. Then, the inductance change rate ΔL is calculated from the obtained measurement value. The uniaxial compressive stress at this time is 1 ton / cm ² and the inductance change rate ΔL is obtained by the following equation.
ΔL = (L ₁ −L ₀ ) / L ₀ × 100 (%)
L ₁ : Inductance value when uniaxial compressive stress is applied L ₀ : Inductance value without applying uniaxial compressive stress

In the present invention, the temperature characteristics were evaluated for the initial permeability μi. Specifically, the temperature characteristics αμ _ir (αμ _{ir (-20 to} 20 ° _C.) ) at _{−20 to} 20 ° C. and the temperature characteristics α μ _ir (αμ _{ir (20 to 100 ° C.)} ) at _{20 to 100 ° C. are} expressed by the following equations. The target is to obtain ± 7 ppm / ° C. or less and ± 6 ppm / ° C. or less, respectively. Preferred αμ _{ir (−20 to 20 ° C.)} and α μ _{ir (20 to 100 ° C.)} are ± 5 ppm / ° C. or less and ± 4 ppm / ° C. or less, respectively, more preferable αμ _{ir (−20 to 20 ° C.)} and αμ _{ir ( 20 to 100 ° C.)} are ± 4 ppm / ° C. or less and ± 2 ppm / ° C. or less, respectively.
αμir _{( −20 to 20 ° C.)} = (μ _{−20 ° C.} −μ _{20 ° C.} ) / (μ _{20 ° C.} ) ²
αμir _{(20 to 100 ° C.)} = (μ _{100 ° C.−} μ _{20 ° C.} ) / (μ _{20 ° C.} ) ²

By setting the variation coefficient CV of Sn to 0.2% or more, both the anti-stress characteristic and the temperature characteristic can be improved. However, if the Sn coefficient of variation CV becomes too high, a decrease in magnetic characteristics, particularly the initial permeability μi, cannot be ignored. Therefore, the Sn variation coefficient CV is preferably 0.5% or less. A more preferable variation coefficient CV of Sn is 0.25 to 0.5%, and a more preferable variation coefficient CV of Sn is 0.3 to 0.5%. There are several methods for controlling the coefficient of variation CV of Sn, as will be described later. However, the SnO ₂ raw material is added after calcining, and the particle size of the SnO ₂ raw material added at this time is increased. It is most effective to do.

Next, the reason for limiting the composition of the Ni—Cu—Zn ferrite material according to the present invention will be described.
In the Ni—Cu—Zn ferrite material of the present invention, Fe ₂ O ₃ , CuO, ZnO and NiO constitute the main component, and SnO ₂ constitutes the subcomponent.
The content of Fe ₂ O ₃ constituting the main component of the Ni—Cu—Zn ferrite material of the present invention is 45 to 49.8 mol%. When the content of Fe ₂ O ₃ is less than 45 mol%, the initial permeability μi and the saturation magnetic flux density Bs are lowered. On the other hand, when the content of Fe ₂ O ₃ exceeds 49.8 mol%, the sintered density is lowered, and the initial magnetic permeability μi, the saturation magnetic flux density Bs, and the anti-stress characteristic are deteriorated. Therefore, in the present invention, the content of Fe ₂ O ₃ is set to 45 to 49.8 mol%. A preferable Fe ₂ O ₃ content is 46 to 49.5 mol%, and a more preferable Fe ₂ O ₃ content is 47 to 49 mol%.

  In the Ni—Cu—Zn-based ferrite material of the present invention, the content of CuO constituting the main component is less than 10 mol% (however, 0 is included). The CuO content also affects the anti-stress properties and magnetic properties. When the CuO content is 10 mol% or more, the initial permeability μi is lowered, and an improvement in the antistress characteristic cannot be expected. The preferable CuO content is 0.5 to 8 mol%, and the more preferable CuO content is 1.5 to 5 mol%, more preferably 2 to 4.8 mol%.

  The content of ZnO constituting the main component of the Ni—Cu—Zn ferrite material of the present invention is 10 to 40 mol%. When the ZnO content is less than 10 mol%, the initial permeability μi is lowered. On the other hand, when the content of ZnO exceeds 40 mol%, the initial permeability μi increases, but the saturation magnetic flux density Bs decreases. Therefore, in the present invention, the ZnO content is set to 10 to 40 mol%. The preferable ZnO content is 15 to 35 mol%, and the more preferable ZnO content is 20 to 30 mol%.

  The balance of the main component of the Ni—Cu—Zn ferrite material of the present invention is NiO. The contents of ZnO and NiO are in a relationship that when one is increased, the other is decreased. By controlling the contents of each other, the initial permeability μi and the saturation magnetic flux density Bs can be adjusted. As one criterion, NiO can be 10 to 40 mol%. When the content of NiO is less than 10 mol%, the saturation magnetic flux density Bs is lowered. On the other hand, when the content of NiO exceeds 40 mol%, the initial permeability μi decreases. The preferred NiO content is 15 to 35 mol%, and the more preferred NiO content is 20 to 30 mol%.

The Ni—Cu—Zn-based ferrite material of the present invention can contain SnO ₂ in the range of 0.2 to 4 wt% with respect to the main component. SnO ₂ has an effect of improving the anti-stress characteristic and the temperature characteristic without impairing the magnetic characteristic. That is, the Ni—Cu—Zn-based ferrite material of the present invention containing SnO ₂ has a small change in the inductance L when no stress is applied and when the stress is applied, and a small change in the initial permeability μi with respect to a temperature change. However, as described above, this effect becomes significant when the variation coefficient CV of Sn is 0.2% or more. Therefore, according to the present invention, it is possible to improve the anti-stress characteristic with respect to the inductance L and further the temperature characteristic of the initial permeability μi with a smaller amount of SnO ₂ content. However, if the SnO ₂ content is less than 0.2 wt%, the effect cannot be sufficiently obtained even if the Sn variation coefficient CV is 0.2% or more. On the other hand, when the content of SnO ₂ exceeds 4 wt%, the antistress characteristics deteriorate and the initial permeability μi decreases. In the present invention, therefore, the amount of SnO ₂ with respect to the main component and 0.2~4wt%. A preferable amount of SnO ₂ is 0.25 to 3.5 wt%, and a more preferable amount of SnO ₂ is 0.4 to 3 wt%.

In the Ni—Cu—Zn-based ferrite material of the present invention, impurities derived from raw materials, and SiO ₂ , Al ₂ O ₃ , MgO, MnO, CaO, Cr ₂ O ₃ , Y ₂ O ₃ , ZrO that are unavoidable in the manufacturing process. It goes without saying that even if an oxide such as ₂ is contained, it is included in the technical scope of the present invention.

The Ni—Cu—Zn-based ferrite material in the present invention is provided as a sintered body. According to the Ni—Cu—Zn based ferrite material of the present invention, it is preferable that this sintered body has a high density in order to have both the antistress characteristic and the magnetic characteristic. 5.1 Mg / m ³ It can have the above sintered density. The sintered body density can be set to 5.2 Mg / m ³ or more, and further to 5.25 Mg / m ³ or more. In the composition defined in the present invention, in order to obtain such a density, it is desirable that the sintering temperature is 1000 ° C. or higher. This point will be mentioned in the description of the manufacturing method described later.

Next, the suitable manufacturing method of the Ni-Cu-Zn type ferrite material by this invention is demonstrated.
The Ni—Cu—Zn based ferrite material of the present invention is characterized in that the coefficient of variation CV of Sn is 0.2% or more. The higher the variation coefficient CV of Sn, the more Se is segregated in the sintered body. The present invention is characterized by segregating rather than improving the dispersibility of Sn.

There are several methods for controlling the dispersibility of Sn. One is to increase the particle size of SnO ₂ powder, which is a raw material of Sn. When SnO ₂ powder having a large particle size is used, SnO ₂ is segregated in the sintered body, and the coefficient of variation CV increases. However, even if SnO ₂ powder having a large particle size is used, care should be taken because if it is mixed and pulverized more than necessary, it becomes finer. Second, SnO ₂ powder as a raw material is added after so-called calcination. The dispersibility of Sn (SnO ₂ ) in the sintered body is lower when added and fired after other raw materials are calcined than when mixed, pulverized, calcined and then fired together with other raw materials. Is to use that. However, even if a step of mixing, pulverizing, and calcining with other raw materials is employed, the dispersibility of Sn (SnO ₂ ) in the sintered body can be adjusted by controlling the mixing and pulverizing conditions.

Hereinafter, it demonstrates in order of a process.
For example, an Fe ₂ O ₃ powder, a CuO powder, a ZnO powder, and a NiO powder are prepared as raw material powders that constitute the main component. In addition to the powders constituting these main components, SnO ₂ powders constituting subcomponents are prepared.
What is necessary is just to select suitably the particle size of each raw material powder to prepare in the range of 0.1-10 micrometers. However, it is preferable for the present invention to select a SnO ₂ powder having a relatively large particle size.
The prepared raw material powder is wet-mixed using, for example, a ball mill. The mixing depends on the operating conditions of the ball mill, but a uniform mixed state can be obtained if it is carried out for about 20 hours. As described above, it is preferable for the present invention that the subcomponent SnO ₂ powder is added not after the wet mixing but after the calcination described later.
In the present invention, not only the above-mentioned main component materials, but also a composite oxide powder containing two or more metals may be used as the main component materials. For example, a complex oxide powder containing Fe and Ni can be obtained by oxidizing and baking an aqueous solution containing iron chloride and Ni chloride. This powder and ZnO powder may be mixed and used as a main component material. In such a case, calcining described later is unnecessary.

After mixing the raw material powder, calcining is performed. In the calcining, the holding temperature may be in the range of 700 to 950 ° C., and the atmosphere may be air. After calcining, preferably after adding SnO ₂ powder, it is pulverized, for example, to an average particle size of about 0.5 to 2 μm. It is preferable to complete this pulverization in a short time in order to make the Sn variation coefficient CV 0.2% or more.

  The pulverized powder composed of the main component and the subcomponent is preferably granulated into granules in order to smoothly execute the subsequent molding step. Granules can be obtained by adding a small amount of a suitable binder such as polyvinyl alcohol (PVA) to the pulverized powder, and spraying and drying it with a spray dryer. The particle size of the obtained granules is preferably about 60 to 200 μm.

  The obtained granule is formed into a desired shape using, for example, a press having a mold having a predetermined shape, and this formed body is subjected to a firing step. Firing is preferably performed in the range of 1010 to 1240 ° C. If it is less than 1010 ° C., it is difficult to obtain a high sintered density, and if it exceeds 1240 ° C., abnormal grain growth occurs and the initial permeability μi decreases. A preferred firing temperature is 1020 to 1210 ° C, and a more preferred firing temperature is 1040 to 1190 ° C.

  As described above, the Ni—Cu—Zn ferrite material according to the present invention can be used as the core of a resin mold type inductance element. In this case, the resin is molded after winding the core, but compressive stress is applied to the core due to curing and shrinkage of the resin. Even when this compressive stress is applied, the Ni-Cu-Zn ferrite material of the present invention has a small variation in inductance L. In addition, the Ni—Cu—Zn ferrite material of the present invention has a small change in initial permeability μi with respect to temperature fluctuation.

Fe ₂ O ₃ powder, ZnO powder, NiO powder and CuO powder were weighed to the composition (mol%) shown in Table 1 as raw material powders constituting the main component.
Next, these raw materials were wet-mixed using a steel ball mill, and the obtained mixed powder was calcined at 900 ° C. for 2 hours. To the obtained calcined powder, SnO ₂ powder of SSA (Specific Surface Area) shown in Table 1 was added in an amount shown in Table 1, and mixed and ground in a steel ball mill. The obtained pulverized powder had an average particle size of 0.5 μm.

Next, an aqueous polyvinyl alcohol solution was added as a binder to each obtained pulverized powder and granulated. Using the thus obtained granules having an average particle diameter of 70 μm, a toroidal sample (outer diameter 20 mm, inner diameter 10 mm, height 5 mm) for electromagnetic property evaluation was obtained by press molding. Moreover, the prism sample (width 5mm, thickness 5mm, length 30mm) for anti-stress characteristic evaluation was obtained by press molding. In addition, all were shape | molded so that a shaping | molding density might be 3.20Mg / m < ³ >. The molded body was fired at 1150 ° C. for 2 hours in the air. 1-7 Ni-Cu-Zn ferrite materials were obtained.

Using the obtained toroidal sample and prism sample, the Sn coefficient of variation CV, the sintered density, the initial permeability μi, the saturation magnetic flux density Bs, the antistress characteristic ΔL, and the temperature characteristic αμir were measured. The measurement conditions are as follows. The obtained results are shown in Table 1. FIG. 1 shows the relationship between the SSA and Sn variation coefficient CV of the SnO ₂ powder, FIG. 2 shows the relationship between the Sn variation coefficient CV and the anti-stress characteristic ΔL, and the relationship between the Sn variation coefficient CV and the temperature characteristic αμir. Is shown in FIG.

Coefficient of variation CV of Sn: Elemental mapping of Sn was performed with EPMA under the following conditions, and the coefficient of variation CV was obtained by dividing the standard deviation of the concentration of Sn at all analysis points by the average value of the concentration of Sn at all analysis points. .
EPMA measurement conditions Equipment used: Field Emission Electron Probe Microanalyzer (FE-EPMA)
JXA-8500F manufactured by JEOL Ltd.
Acceleration voltage: 15 kV
Irradiation current: 0.2 μA
Irradiation time: 45msec / point
Measurement area (X = Y): 204.8 μm × 204.8 μm (0.8 μm step)

Sintering density: The weight of the toroidal sintered body was measured. The volume of the sintered body was determined from the measured values of the outer diameter, inner diameter, and thickness, and the sintered density was determined from this value and the measured weight.
Initial permeability μi: After winding the wire 20 times on the toroidal sample, the initial permeability μi at 100 kHz was measured with an LCR meter (HP4192 manufactured by Hewlett Packard).
Saturation magnetic flux density Bs: A wire was wound around the toroidal sample 40 times, and the applied magnetic field was set to 4000 A / m. The saturation magnetic flux density Bs was measured with a DC magnetization characteristic test apparatus (SY110 manufactured by Metron Giken).

Anti-stress characteristic ΔL: After winding a wire 30 times on the above prismatic sample, an inductance value L ₀ at 100 kHz was measured with an LCR meter (HP4192 manufactured by Hewlett-Packard Company). A compressive stress (1 ton / cm ² = 98 MPa) is applied in the major axis direction of the prismatic sample, the inductance value L ₁ at the time of compressive stress loading is measured, and the inductance change rate ΔL (ΔL = (L ₁ −L ₀ ) / L ₀ ) was calculated.
Temperature characteristic αμir: The initial permeability μi was measured in the range of −20 to 120 ° C., and αμir was determined by the following formula.
αμir: _{−20 to 20 °} C. = (μ _{−20 ° C.} −μ _{20 ° C.} ) / (μ _{20 ° C.} ) ²
αμir: 20 to 100 ° C. = (μ _{100 °} C.−μ _{20 ° C.} ) / (μ _{20 ° C.} ) ²

As shown in FIG. 1, the variation coefficient CV of Sn varies depending on the SSA of the SnO ₂ powder used as a raw material, and the Sn variation coefficient CV can be increased by using the SnO ₂ powder having a low SSA. However, Sample No. From the results of FIG. 1, the SSA of SnO ₂ powder Even if it is lower than 7, it is becoming difficult to obtain a higher coefficient of variation CV of Sn.

Next, as shown in FIG. 2, it can be seen that when the Sn coefficient of variation CV increases, the absolute value of ΔL decreases and the anti-stress characteristic improves. In the present invention, the standard is that ΔL when a compressive stress of 1 ton / cm ² (= 98 MPa) is applied is ± 7% or less, and when the variation coefficient CV of Sn is 0.2% or more, the absolute value of ΔL The value can be 7% or less. If the Sn coefficient of variation CV is 0.25% or more, the absolute value of ΔL can be made 5% or less, and if the Sn coefficient of variation CV is 0.35% or more, the absolute value of ΔL is made 3% or less. It can be seen from FIG. 1 that this can be done.

  As shown in FIG. 3, when the coefficient of variation CV of Sn increases, the temperature characteristic αμir of the initial permeability μi also improves. However, since the temperature characteristic αμir changes from a positive number to a negative number as the Sn coefficient of variation CV increases, it can be said that there is a preferable range. However, even if the Sn variation coefficient CV increases to about 0.5%, the temperature characteristic αμir remains in the range of ± 2 ppm / ° C. Therefore, the preferable variation coefficient CV of Sn for the temperature characteristic αμir is 0.25 to 0.5%, and more preferable variation coefficient CV of Sn is 0.3 to 0.5%.

  On the other hand, since the initial permeability μi tends to decrease as the Sn variation coefficient CV increases, it is necessary to manufacture the Sn variation coefficient CV in consideration of the anti-stress characteristics and the temperature characteristics. It is.

Sample No. 1 in Example 1 was used except that SnO ₂ powder was added at the time of mixing other raw material powders (added before calcination). Similarly to 1 and 4 (added after calcination), a Ni—Cu—Zn-based ferrite material was produced in the same manner, and similarly to Example 1, Sn variation coefficient CV, sintered density, initial permeability μi, saturation The magnetic flux density Bs, the anti-stress characteristic ΔL, and the temperature characteristic αμir were measured. The results are shown in Table 2. Sample No. 8 is the sample No. 1 and sample no. 9 is Sample No. 4 is supported.

As shown in Table 2, the Sn variation coefficient CV can be increased by adding SnO ₂ after calcination. However, if the SSA of SnO _{2 to be} added is lowered, the coefficient of variation CV can be made 0.2% or more even if it is added before calcination. From the results in Table 2, if the mixing and pulverization conditions are the same, the sample No. 5 and 6, it is understood that a coefficient of variation CV of 0.2% or more can be obtained even if SnO ₂ is added before calcination.

Except for the composition shown in Table 3, a Ni—Cu—Zn-based ferrite material was prepared in the same manner as in Example 1, and the Sn variation coefficient CV, the sintered density, and the initial permeability μi as in Example 1. The saturation magnetic flux density Bs, the anti-stress characteristic ΔL, and the temperature characteristic αμir were measured. The results are shown in Table 3. FIG. 4 shows the relationship between the SnO ₂ content and the anti-stress characteristic ΔL, and FIG. 5 shows the relationship between the SnO ₂ content and the temperature characteristic αμir.

As shown in Table 3, FIG. 4 and FIG. 5, by containing SnO ₂ , the anti-stress characteristic ΔL and the initial permeability temperature characteristic αμir can be improved. However, when the amount reaches 5 wt%, the anti-stress characteristic ΔL is remarkably deteriorated and a decrease in the initial permeability μi cannot be ignored. Further, the specific resistance ρ is remarkably lowered. From the above results, the SnO ₂ content is 0.2 to 4 wt%, preferably 0.25 to 3.5 wt%, and more preferably 0.4 to 3 wt%.

  Except for the composition shown in Table 4, a Ni—Cu—Zn-based ferrite material was prepared in the same manner as in Example 1, and the Sn variation coefficient CV, sintered density, and initial permeability μi were also the same as in Example 1. The saturation magnetic flux density Bs, the anti-stress characteristic ΔL, and the temperature characteristic αμir were measured. The results are shown in Table 4.

  As shown in Table 4, when the CuO content increases, the initial permeability μi decreases and the antistress characteristic ΔL and the temperature characteristic αμir tend to deteriorate. Therefore, the CuO content is preferably 8 mol% or less, more preferably 5 mol% or less.

  Except for the composition shown in Table 5, a Ni—Cu—Zn-based ferrite material was prepared in the same manner as in Example 1, and the Sn variation coefficient CV, the sintered density, and the initial permeability μi as in Example 1. The saturation magnetic flux density Bs, the anti-stress characteristic ΔL, and the temperature characteristic αμir were measured. The results are shown in Table 5.

As shown in Table 5, when the Fe ₂ O ₃ content is small, the initial permeability μi and the saturation magnetic flux density Bs are low. Further, when the Fe ₂ O ₃ content is increased, the initial permeability μi is lowered and the anti-stress characteristic ΔL is deteriorated. Therefore, in the present invention, the content of Fe ₂ O ₃ is set to 45 to 49.8 mol%.

  Except for the composition shown in Table 6, a Ni—Cu—Zn-based ferrite material was prepared in the same manner as in Example 1, and the same as in Example 1, Sn variation coefficient CV, sintered density, initial permeability μi, saturation magnetic flux. The density Bs, the anti-stress characteristic ΔL, and the temperature characteristic αμir were measured. The results are shown in Table 6.

  As shown in Table 6, when the NiO content is small, the saturation magnetic flux density Bs tends to be low. Further, when the NiO content is increased, the initial permeability μi is lowered and the anti-stress characteristic ΔL is deteriorated. Therefore, in the present invention, the NiO content is preferably 10 to 40 mol%.

Is a graph showing the relationship between the coefficient of variation CV of the SnO ₂ powder SSA and Sn. It is a graph which shows the relationship between the variation coefficient CV of Sn, and the anti-stress characteristic (DELTA) L. It is a graph which shows the relationship between the variation coefficient CV of Sn, and the temperature characteristic (alpha) microir. Is a graph showing the relationship between the content and the anti-stress characteristic ΔL of SnO _2. Is a graph showing the relationship between the content and the temperature characteristics αμir of SnO _2.

Claims (4)

The composition of the main _{component, Fe 2 O 3: 45~49.8mol%} , CuO: less than 10 mol% (provided that includes 0), ZnO: 10~40mol%, NiO: a sintered body which is a remainder,
The sintered body is
A Ni—Cu—Zn based ferrite material comprising 0.2 to 4 wt% of SnO ₂ as a subcomponent, and having a Sn variation coefficient CV of 0.2% or more. The sintered body is
Containing 0.4 to 3 wt% SnO ₂ with respect to the main component as the subcomponent,
The Ni-Cu-Zn-based ferrite material according to claim 1, wherein a coefficient of variation CV of Sn is 0.25 to 0.5%.   The Ni-Cu-Zn-based ferrite material according to claim 1 or 2, wherein CuO as the main component is 1 to 5 mol%. _{Fe 2 O 3: 45~49.8mol%,} CuO: less than 10 mol% (provided that includes 0), ZnO: 10~40mol%, NiO: a step of a raw material mixture of the main component having a composition of balance calcination ,
Adding 0.2-4 wt% SnO ₂ raw material powder to the reaction product obtained by the calcining, mixing with the reaction product, and crushing;
A step of pressure-molding the obtained pulverized product to obtain a molded body,
Firing the molded body to obtain a sintered body;
The manufacturing method of the Ni-Cu-Zn type ferrite material characterized by including these.

Images