JP3298156B2 - Oxide magnetic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide magnetic material used for a core for a high frequency low loss chip coil and the like.
More specifically, the present invention relates to a low-loss, low-open-porosity oxide magnetic material suitable for use in a high-frequency band of 100 MHz or more.

[0002]

2. Description of the Related Art A wound type chip coil is an electronic component used for an amplification circuit and an oscillation circuit, and is widely used in fields such as video equipment and communication equipment. In particular, in recent years, with the increase in precision and frequency of electronic circuits used in these devices, 100 MHz
A coil having a high Q in the above high frequency band has been required.

As a magnetic core material for such a high frequency chip coil, for example, a magnetic material such as NiZn ferrite is used.

However, this NiZn ferrite has a μi
(Permeability) is large.
Is attenuated.

There is also known a method of obtaining a ferrite having a Q exceeding 100 at 100 MHz by suppressing the grain size of the sintered body to, for example, 1 μm or less. However, when a magnetic core is made of ferrite with controlled grain size, the open porosity is large, and the electrode material penetrates when applying and baking the electrode to the formed chip coil, causing short-circuit failure. There is a problem.

Therefore, at present, a ferrite material suitable for a magnetic core material for a high-frequency chip coil that can maintain a high Q even in a high-frequency band of 100 MHz or more cannot be obtained.

An object of the present invention is to provide an oxide magnetic material which has a low open porosity and maintains a high Q even in a high frequency band of 100 MHz or more.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted various experiments and studies and found that Fe ₂ O ₃ ,
MgO, CuO, V ₂ O ₅ , and NiO are blended at a predetermined ratio, and are fired at a temperature of, for example, about 1000 to 1100 ° C., so that the open porosity is as low as 5% or less, and the And found that a magnetic material maintaining a high Q can be obtained, and completed the present invention.

That is, the oxide magnetic material of the present invention comprises:
Fe ₂ O ₃ , MgO, CuO, V ₂ O ₅ , and NiO, whose contents are Fe ₂ O ₃ : 44.0 to 49.0 mol% MgO: 3.0 to 13.5 mol% CuO: 0 _{.4~ 4.0mol% V 2 O 5:} 0.5~ 2.5mol% NiO: characterized in that it contains in a proportion such that the remaining amount.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be described below in more detail with reference to embodiments.

[Embodiment 1] Fe ₂ O ₃ , NiO, MgO,
A predetermined ratio of CuO and V ₂ O ₅ was mixed, wet-mixed, and dried to prepare a dry powder having a composition ratio (final composition ratio) as shown in Table 1. The dry powder was prepared by changing the ratio of V ₂ O ₅ while keeping the ratio (mol%) of Fe ₂ O ₃ , MgO, and CuO constant, and changing the balance to Ni.
It is prepared by blending each raw material so as to be O.

[0012]

[Table 1]

In Table 1, those marked with * in the sample numbers indicate comparative examples outside the scope of the present invention, and the others indicate examples within the scope of the present invention.

Then, the dry powder having the composition shown in Table 1 was
The mixture was calcined at 900 ° C. for 2 hours, put in a polyethylene pot together with cobblestone and distilled water, mixed and pulverized for 24 hours, and then added with an organic binder and mixed for another 2 hours. The obtained mixture was dried.

Next, this was granulated by a spray drying method, molded into a predetermined shape (shape of a chip coil core), and fired at a temperature of 1050 ° C. for 2 hours to prepare a chip coil core.

The core for the chip coil is 0.1
A mmφ conducting wire was wound five times, and Q at 100 MHz was measured by an impedance analyzer. Q and V ₂ O ₅
FIG. 1 shows the relationship with the content (mol%).

The chip coil core was placed in boiling water and boiled for one hour, and the open porosity was measured. FIG. 2 shows the relationship between the open porosity and the V ₂ O ₅ content (mol%).

When configuring a chip coil for a communication device,
The inductance Q is preferably 100 or more at 100 MHz, and the open porosity is preferably 5% or less.
Therefore, Q and open porosity were examined as one criterion of the oxide magnetic material that preferably satisfies the two requirements that Q at 100 MHz is 100 or more and open porosity is 5% or less. .

First, regarding the open porosity, as shown in FIG. 2, when V ₂ O ₅ is not added, that is, V ₂ O ₅
When the addition amount (content ratio) of 0% is 0 mol%, the open porosity is 5%.
However, as the added amount of V ₂ O ₅ increases, the open porosity decreases, and when the V ₂ O ₅ content exceeds 0.5 mol%, the open porosity becomes 5% or less, Thereafter, it was found that the open porosity did not increase even if the added amount of V ₂ O ₅ was increased.

On the other hand, as for Q, as shown in FIG. 1, when V ₂ O ₅ is not added, Q at 100 MHz is 50%.
0 or more, but as the added amount of V ₂ O ₅ increases, Q
When the V ₂ O ₅ content exceeds about 2.5 mol%, Q
Was found to decrease to less than 100. this is,
It is considered that the addition amount (substitution amount) of V ₂ O ₅ became excessive, which caused abnormal growth of ferrite particles, increased eddy current loss in a high frequency band, and decreased Q at 100 MHz.

Therefore, the added amount (content) of V ₂ O ₅
Is preferably in the range of 0.5 to 2.5 mol%.

Example 2 Fe ₂ O ₃ , NiO, MgO,
A predetermined ratio of CuO and V ₂ O ₅ was blended, wet-pulverized and mixed, and then dried to prepare a dry powder having a composition ratio (final composition ratio) as shown in Table 2. In addition, this dry powder has a ratio (mol) of Fe ₂ O ₃ , CuO, and V ₂ O _5.
%) While keeping the ratio constant by changing the ratio of MgO by 1.0 mol% and blending the respective raw materials so that the balance is NiO.

[0023]

[Table 2]

In Table 2, samples marked with an asterisk (*) indicate comparative examples outside the scope of the present invention, and others indicate examples within the scope of the present invention.

Then, a core for a chip coil was prepared using the dry powder having the composition shown in Table 2 in the same manner and under the same conditions as in Example 1.

Then, 0.1% is added to the core for the chip coil.
A mmφ conducting wire was wound five times, and Q at 100 MHz was measured by an impedance analyzer. Q and MgO
FIG. 3 shows the relationship with the content (mol%).

Further, the chip coil core was placed in boiling water and boiled for 1 hour, and the open porosity was measured. FIG. 4 shows the relationship between the open porosity and the MgO content (mol%).

As shown in FIG. 3, as the amount (content) of MgO increases, the Q at 100 MHz increases. On the other hand, when the addition amount of MgO is less than 3.0 mol%, the effect of increasing Q becomes small, and Q at 100 MHz becomes 10%.
It will drop below 0. On the other hand, as for the open porosity, as shown in FIG. 4, the open porosity increases as the amount of added MgO increases, and the MgO content becomes 13 mol.
%, The open porosity exceeded 5%.

Therefore, the added amount (content) of MgO
Is preferably in the range of 3.0 to 13.5 mol%.

Example 3 Fe ₂ O ₃ , NiO, MgO,
A predetermined ratio of CuO and V ₂ O ₅ was blended, wet-pulverized, mixed, and dried to prepare a dry powder having a composition ratio (final composition ratio) as shown in Table 3. In addition, this dry powder has a ratio (mol) of Fe ₂ O ₃ , MgO and V ₂ O _5.
%) While keeping the ratio constant, while changing the CuO ratio by 0.5 mol% at a time, and blending the respective raw materials so that the balance is NiO.

[0031]

[Table 3]

In Table 3, samples marked with an asterisk (*) indicate comparative examples outside the scope of the present invention, and others indicate examples within the scope of the present invention.

Then, a core for a chip coil was prepared using the dry powder having the composition shown in Table 3 in the same manner and under the same conditions as in Example 1.

[0034] Then, 0.1
A mmφ conducting wire was wound five times, and Q at 100 MHz was measured by an impedance analyzer. Q and CuO
FIG. 5 shows the relationship with the content (mol%).

Further, the chip coil core was placed in boiling water and boiled for 1 hour, and the open porosity was measured. FIG. 6 shows the relationship between the open porosity and the CuO content (mol%).

As shown in FIG. 6, when the added amount (content) of CuO is less than 0.4 mol%, the open porosity exceeds 5%, but the added amount (content) of CuO is 0.1%. When the content exceeds 4 mol%, the open porosity becomes 5% or less, and it is found that the open porosity decreases as the added amount of CuO increases.
On the other hand, as for Q, for example, as shown in FIG.
100 when the added amount (content) of CuO is 1.0 mol%
Although the Q at MHz is about 330, the Q decreases as the added amount of CuO increases, and the CuO content becomes 4.0 mol%.
It was found that Q was less than 100 when it exceeded.

Therefore, the added amount (content) of CuO
Is preferably in the range of 0.4 to 4.0 mol%.

Example 4 Fe ₂ O ₃ , NiO, MgO,
A predetermined ratio of CuO and V ₂ O ₅ was mixed, wet-pulverized and mixed, and then dried to prepare a dry powder having a composition ratio (final composition ratio) as shown in Table 4. In addition, this dry powder contains MgO, CuO and V ₂ O _{5 at} a ratio (mol
%) While maintaining the ratio of Fe ₂ O ₃ to 1.0 mol%.
It was prepared by blending the respective raw materials so that the balance was NiO.

[0039]

[Table 4]

In Table 4, samples marked with an asterisk (*) indicate comparative examples outside the scope of the present invention, and others indicate examples within the scope of the present invention.

Then, using the dry powder having the composition shown in Table 4, a core for a chip coil was prepared in the same manner and under the same conditions as in Example 1 above.

Then, 0.1% is added to the core for the chip coil.
A mmφ conducting wire was wound five times, and Q at 100 MHz was measured by an impedance analyzer. Q and Fe ₂
FIG. 7 shows the relationship with the O ₃ content (mol%).

Further, the chip coil core was placed in boiling water and boiled for 1 hour, and the open porosity was measured. FIG. 8 shows the relationship between the open porosity and the Fe ₂ O ₃ content (mol%).

As shown in FIG. 8, when the added amount (content) of Fe ₂ O ₃ is less than 44.0 mol%, the open porosity exceeds 5% (for example, when the Fe ₂ O ₃ content is 43.0 mol%
, The open porosity is 10%), but as the amount of Fe ₂ O ₃ added increases, the open porosity decreases and the Fe ₂ O ₃ content becomes 4%.
When the content exceeds 4.0 mol%, the open porosity becomes 5% or less. Thereafter, the open porosity decreases as the added amount of Fe ₂ O ₃ increases. However, when the Fe ₂ O ₃ content exceeds 49 mol%, the open porosity decreases. It was found that the porosity increased and the open porosity increased to 20% or more when the Fe ₂ O ₃ content became 50 mol%. On the other hand, Q
As for, as shown in FIG. 7, for example, Fe ₂ O ₃
100 MH when the addition amount (content) of is 33.0 mol%
Although the Q of z is as large as about 230, the Q decreases as the added amount of Fe ₂ O ₃ increases, and the Fe ₂ O ₃ content becomes 49 mol%.
In the process of increasing from 100 to 50 mol%,
It turned out to be 00 or less.

Therefore, the added amount (content) of Fe ₂ O ₃
Is preferably in the range of 44.0 to 49.0 mol%.

[0046]

As described above, the oxide magnetic material of the present invention
The charge is Fe_TwoO_Three, MgO, CuO, V 2O_Five, And NiO
And the content thereof is Fe_TwoO_Three: 44.0-4
9.0 mol%, MgO: 3.0 to 13.5 mol%, Cu
O: 0.4-4.0 mol%, V_TwoO_Five: 0.5 to 2.5 mol
%, NiO: balance
Therefore, loss in high frequency band can be suppressed
And obtain an oxide magnetic material having a low open porosity of the sintered body.
It can be used as a core for high-frequency chip coils.
By using it as a material, Q in the high frequency band
Large and short-circuit failure due to penetration of electrode material
To manufacture high frequency low loss chip coils without causing
It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the V ₂ O ₅ content and Q at 100 MHz.

FIG. 2 is a diagram showing the relationship between the V ₂ O ₅ content and the open porosity.

FIG. 3 is a diagram showing the relationship between the MgO content and Q at 100 MHz.

FIG. 4 is a diagram showing the relationship between the MgO content and the open porosity.

FIG. 5 is a diagram showing the relationship between the CuO content and Q at 100 MHz.

FIG. 6 is a diagram showing the relationship between the CuO content and the open porosity.

FIG. 7 is a graph showing the relationship between the Fe ₂ O ₃ content and Q at 100 MHz.

FIG. 8 is a graph showing the relationship between the Fe ₂ O ₃ content and the open porosity.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 1/12-1/375

Claims (1)

(57) [Claims] 1. The contents of Fe ₂ O ₃ , MgO, CuO, V ₂ O ₅ , and NiO are as follows: Fe ₂ O ₃ : 44.0 to 49.0 mol% MgO: 3.0 to 13. 5mol% CuO: 0.4~ 4.0mol% V 2 O 5: 0.5~ 2.5mol% NiO: oxide magnetic material characterized in that a proportion such that the remaining amount.