JP5580961B2 - Oxidized magnetic material and manufacturing method thereof - Google Patents

Description

  The present invention relates to an oxidized magnetic material and a method for manufacturing the same, and more particularly to a material that can be applied in a high frequency region.

  As one of magnetic materials used for various electronic circuit components such as filters, inductors, transformers, and antennas, there is an oxidized magnetic material of Ni—Cu—Zn ferrite. For example, the magnetic characteristics required for inductors are required to have high magnetic characteristics and low magnetic loss at the operating frequency. Low loss materials are required. This tendency is not limited to inductors, and the same applies to magnetic materials used for other electronic components.

  In this type of Ni—Cu—Zn-based oxidized magnetic material, Co is added as an additive in addition to Fe, Ni, Cu, and Zn as main components for the purpose of reducing loss in a high frequency region. Is done. In addition, additional additives may be added for various purposes. This type of technology is disclosed in, for example, Patent Documents 1 and 2. In order to produce these various oxidized magnetic materials, a mixture of main components and additives mixed at a predetermined composition ratio is calcined, pulverized, and then fired.

JP 2005-306668 A JP 2004-172396 A

  In conventional oxide magnetic materials, Co is added in order to reduce loss at high frequencies. However, when Co is added in a large amount, the temperature characteristic of the L value is lowered. That is, the change of the L value with respect to the temperature change becomes large. In order to improve the temperature characteristics, for example, glass materials are added simultaneously. However, the addition of a glass material, which is a nonmagnetic material, reduces the abundance ratio of the magnetic material, resulting in a new problem that the magnetic loss at a high frequency is increased compared to the addition of Co alone.

  The present invention provides an oxidized magnetic material and a method for producing the same, which can prevent deterioration of magnetic loss at high frequencies while reducing the temperature change of L with respect to Ni-based ferrite containing Co.

To solve the above problems, a manufacturing method of the oxide magnetic material of the present invention, (1) _Fe 2 _{O 3} is 45～50.5Mol% as a main component, ZnO is 5~33mol%, CuO is 5 to 15 mol% In the method for producing a ferrite oxide magnetic material with the balance being NiO, each material constituting the main component is weighed, mixed, and calcined so as to match the above composition range. And, with respect to the powder obtained by pulverization after the calcining, CoO is 2.0 wt% or less (not including 0), and the total addition amount including both SiO ₂ and ZrO ₂ is 0.2 wt% or less. MgO was added at 0.15 wt% or less (excluding 0), mixed and fired.

(2) Preferably, the total amount of the SiO ₂ and ZrO ₂ added is 0.2 wt%.

(3) oxidation magnetic material of the present invention, the main component is _Fe 2 _{O 3} is 45~50.5mol%, ZnO is 5~33mol%, CuO is at 5 to 15 mol%, oxide magnetic material of the rest of NiO ferrite In addition, CoO is 2.0 wt% or less (excluding 0), SiO ₂ and ZrO ₂ are both included and the total addition amount is 0.2 wt% or less, and MgO is 0.15 wt% or less (not including 0). It was assumed that it was added after calcination.

In the Ni-based ferrite composed of the main component, the loss at high frequency is reduced by adding Co as an additive. From this point, it is better to add Co (CoO) than the one without any addition, and the higher the addition amount, the higher the frequency response becomes, and this is preferable. However, when a large amount of Co is added, the temperature change of L increases, but in the present invention, a slight amount of Si and Zr are added and mixed after calcining, and they are added at the same time. Becomes ZrSiO ₄ . Since ZrSiO ₄ has a thermal expansion coefficient close to that of ferrite, it is possible to prevent L from being reduced due to a stress generated due to a difference in expansion coefficient accompanying a temperature change. Therefore, the temperature characteristics can be improved by adding appropriate amounts of SiO ₂ and ZrO ₂ after calcination. The addition amount is preferably a certain amount rather than a slight amount close to 0 because the conversion effect is exhibited. However, when the addition amount is more than necessary, the amount that does not become ZrSiO ₄ increases, so the above effect is reduced. According to the experimental results, the total value of the added amounts of SiO ₂ and ZrO ₂ is 0.2 wt% or less.

In addition, since ZrO ₂ , SiO ₂ , and MgO are vitrified, CoO mixed and added together after calcination is uniformly dispersed in the ferrite, so that the magnetic properties are improved and the glass is sintered. The temperature characteristics of L can be improved while improving the magnetic characteristics at high frequencies with the addition of CoO by controlling the crystal grain size by improving the properties. When CoO is added to the base material together with the main component and calcined, it reacts with the main component, so that uniform dispersion of CoO accompanying the above vitrification hardly occurs.

  Furthermore, the more Co is added to improve the magnetic properties, the better. The present invention is premised on an oxide magnetic material to which Co is added, and therefore the lower limit is greater than 0 (0 is not included). Become. And CoO cannot add the amount exceeding 2.0 wt% as an additive after calcination because it brings about a significant reduction in μ value. Therefore, the upper limit of CoO is 2.0 wt% in order to configure the oxidized magnetic material as an additive after calcining.

  Furthermore, in the present invention, the additive is added after calcination. This is because of the following reasons. That is, when Co is added at the time of blending, Co is more uniformly dispersed and is present in the ferrite, and the magnetic properties show good results. However, in order to improve the temperature change of L, it is not preferable that all of the added Co uniformly enter the ferrite. By simultaneously adding Si, Zr, etc., other additives and Co react with each other, segregate between ferrite particles, and exist in a different phase. Since the temperature change of L is reduced due to the local difference in microstructure due to the heterogeneous phase present in these ferrites, the strain, etc. where the heterogeneous phase exists, it is not added at the time of blending where Co is uniformly dispersed. It was added after calcination.

  In the present invention, the composition has a desired composition ratio, and the additive is mixed after calcining, so that the magnetic characteristics can be extended to a high frequency, the increase in magnetic loss can be reduced, and the temperature change rate of L can be reduced. be able to.

6 is a graph showing frequency characteristics of μ ′ and μ ″. It is a figure which shows the temperature characteristic of L.

Hereinafter, preferred embodiments of the present invention will be described. The oxidized magnetic material according to the present invention is composed mainly of ferric oxide (Fe ₂ O ₃ ), zinc oxide (ZnO), copper oxide (CuO), nickel oxide (NiO), and Ni containing Fe, Ni, and Zn. The composition of the system ferrite (NiCuZn system ferrite).
Specifically, the main component is
Fe ₂ O ₃ is 45~50.5mol%,
ZnO is 5 to 33 mol%,
CuO is 5 to 15 mol%, and the balance is NiO. Each composition range constituting the main component includes a boundary value.

And with respect to this main component,
CoO is added at 2.0 wt% or less. The total amount of SiO ₂ and ZrO ₂ added is 0.2 wt% or less. MgO is added at 0.15 wt% or less. Since both CoO and MgO are added, 0 wt% is not included. Each of these additives is added after calcining the base material composed of the main component. More preferably, the additives are added simultaneously. At this time, the total amount of addition of SiO ₂ and ZrO ₂ should be 0.2 wt%.

  Next, a preferred embodiment of the method for producing an oxidized magnetic material will be described. First, each raw material component constituting the above-described base material (main component) is weighed so as to satisfy the conditions within the above composition range, wet-mixed to produce a mixed powder, dried, and crushed And calcining. The calcination temperature is calcination at 700 to 850 degrees and pulverized with a ball mill. Each processing step up to these calcinations is the same as that generally performed. However, conventionally, the additive is also mixed with the base material before calcining and calcined together with the main component, but in this embodiment, it is not added to the starting material.

Next, CoO, SiO ₂ , ZrO ₂ , and MgO that are weighed so as to be within the above range are added to the obtained powder after calcining, and polyvinyl alcohol (PVA) is added as a binder. To obtain a powder having a predetermined particle diameter.

  Next, a pressure for molding is applied to the granulated powder to form, for example, a ring shape, followed by firing. Firing, for example, produces a sintered body by firing at a temperature in the range of 900 to 1200 ° C. for a predetermined time.

  Various samples were manufactured by the manufacturing procedure described above. In other words, in order to demonstrate the effect of the present invention, a plurality of samples are manufactured by changing the kind and amount of additives added to the main component, and magnetic characteristics μ ′, loss μ ″, resonance frequency fr for each sample. , Density, core loss, saturation magnetic flux density (Bm), holding force Hc, temperature change rate of L, etc. The results are shown in Tables 1 and 2 and FIGS.

As the reference values for evaluating these values, the main components are the same, and the values of the sample (comparative reference sample: sample 1) manufactured by adding only CoO to the additive are used, and fr is greater than the reference value. And the temperature change rate of L was smaller than the standard. In Tables 1 and 2, Co means CoO, Si means SiO ₂ , Zr means ZrO ₂ , and Mg means MgO.

First, Table 1 shows that, in order to evaluate at 10 MHz, the amount of CoO is fixed at 0.3 wt% as a reference for comparison, and the composition ratio of other additives (SiO ₂ , ZrO ₂ , MgO) is changed. It is the result of the manufactured sample. This sample had a ring shape (outer diameter 25 mm, inner diameter 15 mm, height 5 mm). The main component of the formulation, _Fe 2 _{O 3} is 45~50.5mol%, ZnO is 5~33mol%, CuO is the remainder as in the range of 5 to 15 mol% was NiO.

  As conditions at the time of manufacture, calcination was performed at a top temperature of 750 ° C. in the atmosphere, and pulverization after calcination was performed by a ball mill for 20 hours. And it baked with respect to the ring-shaped molded object at the top temperature of 1100 degreeC in air | atmosphere, and obtained the sintered compact.

  From the results of Samples 2 to 4, when the added amount of MgO is 0 (Sample 2), the rate of change in temperature of L is bad, which is outside the scope of the present invention. In this case, the desired effect (improvement of the temperature characteristic of L in the high frequency region) can be obtained only by 0.1 wt%. As shown in Sample 5, when MgO is 0.2 wt%, the temperature characteristics of L and the resonance frequency fr are below the reference value. Therefore, from the experimental results of Sample 4 and Sample 5, the upper limit criticality of MgO is 0.15 wt%, and based on the experimental results of Sample 2 to Sample 5, the range of MgO is 0 to 0.15 wt% or less (0 Not included) is good.

Samples 6 to 14 are experimental results in which the addition amount of MgO is fixed to 0.1 wt% and the addition amounts of SiO ₂ and ZrO ₂ are changed. From the experimental results of Samples 6 and 12, when either ZrO ₂ or SiO ₂ is not added, it can be confirmed that the temperature characteristics of L are poor even if the amount of other additives added satisfies the conditions. Therefore, it can be confirmed that both SiO ₂ and ZrO ₂ are essential. As shown in Sample 7 to Sample 11, if the total of these two additives is 0.2 wt% or less, desired characteristics can be obtained under other conditions including the temperature characteristic of L. As shown in the experimental results of Samples 13 and 14, it was confirmed that the temperature characteristics of L deteriorated when the total amount of SiO ₂ and ZrO ₂ exceeds 0.2 wt%. Therefore, it can be said that both SiO ₂ and ZrO ₂ are added, and the total addition amount of both is preferably 0.2 wt% or less. The base material composition in the experimental results shown in Table 1 is 49.5 mol% for Fe ₂ O ₃ , 23.5 mol% for ZnO, 21 mol% for NiO, and 6 mol% for CuO. When the experiment was performed while changing the composition of the base material, the same kind of tendency was observed although the numerical values of the specific characteristics were different, and if the composition ratio of the base material and the additive amount were within the scope of the present invention, L The temperature change was good.

  On the other hand, Table 2 shows the experimental results when the amount of CoO added is also changed. As shown in Sample 15, Sample 16, Sample 22, and Sample 23, it can be confirmed that the temperature characteristic of L is good up to 2.0 wt% of CoO. As shown in Sample 24, the amount of CoO added is 2. It has been confirmed that the temperature characteristic of L is deteriorated when it exceeds 5 wt%. Thereby, it can be said that the addition amount of CoO is preferably 2.0 wt% or less. In addition, as shown in Samples 17 to 21, even if the addition amount of CoO is 1.5 wt% within the range, if the addition amount of other additives is out of the range of the present invention, the temperature characteristics of L deteriorate. Was confirmed.

Incidentally, the base material composition of the sample 15 to 21 shown in Table 2 is, _Fe 2 _{O 3} is 49.5 mol%, ZnO is 30 mol%, NiO is 14.5mol%, CuO is 6 mol%. The base material compositions of Samples 22 to 24 are 49.5 mol% for Fe ₂ O ₃ , 33 mol% for ZnO, 11.5 mol% for NiO, and 6 mol% for CuO. Furthermore, when the experiment was performed by changing the base material composition, the same kind of tendency was seen although the numerical values of the specific characteristics were different, and if the composition ratio of the base material and the additive amount were within the scope of the present invention, The L temperature change was good.

Claims (3)

_Fe 2 _{O 3} is 45～50.5Mol% as a main component, ZnO is 5~33mol%, CuO is at 5 to 15 mol%, the balance being a process for the preparation of oxide magnetic material ferrite and NiO,
Each material constituting the main component is weighed so as to match the above composition range, mixed, calcined,
To powder obtained by grinding after calcining, (not including 0) 2.0 wt% or less CoO, total together comprise the added amount of SiO ₂ and ZrO ₂ is less 0.2 wt%, the MgO A method for producing an oxidized magnetic material, wherein 0.15 wt% or less (excluding 0) is added, mixed, and fired. The method for producing an oxidized magnetic material according to claim 1, wherein the total amount of SiO ₂ and ZrO ₂ is 0.2 wt%. Main components _Fe 2 _{O 3} is 45~50.5mol%, ZnO is 5~33mol%, CuO is at 5 to 15 mol%, the remainder in the ferrite NiO,
CoO less 2.0 wt% (not including 0), the total of both include the added amount of SiO ₂ and ZrO ₂ is less 0.2 wt%, MgO less 0.15 wt% of (not including 0) calcining An oxidized magnetic material characterized by being added later.

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