JPH0851011A - Magnetic oxide material - Google Patents

Abstract

PURPOSE:To obtain a magnetic oxide material in which variation of inductance is suppressed even for a high external stress while suppressing decrease of inductance after application of an external field. CONSTITUTION:The magnetic oxide material is obtained by adding 0-10wt.% of SiO2 (0wt.% is excluded) and 0-10wt.% of Bi2O3 to a composition containing 5-24.5mol% of Fe2O3, 0-30mol% of CuO (0mol% is excluded), and the remainder of NiO or further adding 0-0.5wt.% of Co3O4 (0wt.% is excluded) thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to communication equipment such as PHS,
The present invention relates to an oxide magnetic material serving as a magnetic core material for an inductor having a structure coated with an epoxy resin or the like used in a circuit of a portable VTR or the like.

[0002]

2. Description of the Related Art As an inductor, there is a case where a magnetic core is wound and then molded with resin or the like. In such a case, the stress applied to the core causes a decrease in inductance, and it is possible to temporarily reduce the inductance from the outside. There is a problem in that the inductance is reduced by the magnetic field that is applied. For example, as disclosed in JP-A-3-93667, 25-45 mol% Fe ₂ O ₃ , 0-20
mol% ZnO, the rest NiO and CuO,
A spinel-type composition in which the molar ratio of O is higher than that of CuO, and 0.1 to 12 wt% of Bi as a minor component is used.
It is proposed that the material containing ₂ O ₃ and 0.05 to 4.0 wt% of SiO ₂ has little loss even at a high frequency of 1 MHz or more, and has little decrease in inductance due to external pressure and magnetic field application. Has been done.

[0003]

There is a demand for further improvement with respect to the change of the inductance due to the external stress and the decrease of the inductance after the application of the external magnetic field, and the change of the inductance is small even under the large external stress. ,
It is an object of the present invention to provide an oxide magnetic material whose inductance is less likely to decrease after application of an external magnetic field.

[0004]

SUMMARY OF THE INVENTION The present invention relates to Fe ₂ O ₃ 5
To 24.5 mol%, CuO 0 to 30 mol% (excluding 0 mol%) and the balance NiO to the main component consisting of SiO ₂ 0 to 10 wt% (however, 0 wt%
Not included), Bi ₂ O ₃ 0-10 wt% (however, 0w
(not including t%). The present invention also provides that the above material contains Co ₃ O ₄ in an amount of 0 to 0.5 wt%.
(However, 0 wt% is not included).

[0005]

The present invention has a Fe ₂ O ₃ content of 24.5 mol.
It has been found that the decrease of the inductance after application of the external magnetic field is small when it is less than or equal to%. The reason why each component is limited in the present invention is as follows. Fe
_If the content of ₂ O ₃ exceeds 24.5 mol%, the decrease in inductance after applying a magnetic field becomes large, and
If it is less, the magnetic permeability will be 1.5 or less, and it will not be useful as a magnetic material. When CuO exceeds 30 mol%, the magnetic permeability changes sensitively under the firing conditions and the reproducibility of the characteristics is poor. S
When iO ₂ exceeds 10 wt%, the sinterability deteriorates and the product strength decreases. When Bi ₂ O ₃ exceeds 10 wt%, the magnetic permeability is significantly reduced. When Co ₃ O ₄ exceeds 0.5 wt%, the magnetic field deterioration becomes large.

[0006]

EXAMPLES Fe ₂ O ₃ 20.0 mol%, CuO 2.
5 mol%, NiO 77.5 mol% as the main component, S
iO ₂ 0.6 wt%, Bi ₂ O ₃ 4.0 wt%, Co ₃
The raw materials containing 0.1 wt% of O ₄ are mixed to obtain 900
After calcination for 2 hours at ℃, it was pulverized by a vibration mill and an attritor to prepare a ferrite powder of 1.0 to 1.5 μm.
This was granulated to obtain a 30φ toroidal shaped body and a square bar (5 × 5 × 15 mm) shaped body. A sample was prepared by firing this in air at 1050 ° C. for 2 hours. This is referred to as actual sister example 1.

The fired 30φ toroidal core was used to measure magnetic permeability, Q, relative temperature coefficient (αμr), and sintered density. The square bar was processed into 2 × 2 × 10 mm and demagnetized, and then a coated conductive wire with a diameter of 0.1 mm was wound in a tight winding of 40 turns, and the stress characteristics were measured. This stress characteristic is 5
by applying a pressure of ^{kg / mm 2, 10kg / mm} 2, the inductance before applying pressure and L1, the inductance is measured while applying the above load in the axial direction, and L2, (L2-L1) / Change rate (%) by L1 * 100
And Regarding the magnetic field characteristics, 10 kg / mm ²
The magnetic field of 100 mT is momentarily applied under the condition that the load is applied, and after removing the external magnetic field, the inductance is measured,
L3, and the rate of change (%) was calculated from (L3-L2) / L1 * 100.

Further, each sample was prepared with the composition ratio shown in Table 1 in the same manner as in Example 1 above, and the characteristics were evaluated. The characteristics of each sample are shown in Table 2.

[0009]

[Table 1]

[0010]

[Table 2]

As can be seen from Tables 1 and 2, the actual sisters of the present invention are not much different from the conventional examples in the pressurizing characteristics, but are significantly improved in the magnetic field characteristics as compared with the conventional examples. Further, in the present invention, PbO may be added as an additive,
In this case, PbO is effective in promoting sintering, but 10 wt.
%, The magnetic permeability will drop significantly, so 10 wt%
The following is desirable.

[0012]

According to the present invention, it is possible to obtain a magnetic material in which the change in inductance is small when an external stress is applied and the decrease in inductance due to the influence of an external magnetic field is extremely small. As a result, when used as a chip inductor, there is little change in the inductance due to the stress caused by the resin mold after winding, and the inductance decreases when attracted by the magnet when using an automatic mounting machine. It is possible to obtain a chip inductor with less power consumption, which is industrially beneficial.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C04B 35/28 B

Claims (2)

[Claims] 1. Fe ₂ O _{3 5 to} 24.5 mol%, Cu
O 0~30mol% (however, not including 0 mol%), relative to the main component of the balance of NiO, SiO ₂ 0
-10 wt% (excluding 0 wt%), Bi ₂ O ₃
An oxide magnetic material comprising 0 to 10 wt% (excluding 0 wt%). 2. The method according to claim 1, wherein Co ₃ O ₄ is added to 0 to 0.
An oxide magnetic material containing 5 wt% (excluding 0 wt%).