JP2515184B2 - Method for producing nickel-zinc ferrite - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a nickel-zinc system ferrite, and more specifically, it reduces the initial magnetic permeability by adding a small amount of indium oxide (In ₂ O ₃ ) and firing it. The present invention relates to a method capable of improving the temperature characteristic of the initial magnetic permeability without causing it.

[0002]

2. Description of the Related Art With the miniaturization of circuits, it is becoming more and more important to stabilize the characteristics of high frequency ferrite cores against temperature changes. For example, when a circuit is constructed by combining a coil using a ferrite core and a chip capacitor or the like, one temperature characteristic is set to positive (+) and the other temperature characteristic is set to negative (-) to cancel each other out, and the overall temperature characteristic is set. Is being improved. Due to recent technological advances, the temperature characteristics of chip capacitors are relatively good,
Along with this, it is required to further reduce the temperature characteristics of the ferrite core.

The nickel-zinc type ferrite is manufactured through the steps of calcination, crushing, molding and firing, which are main raw materials such as Fe ₂ O ₃ , NiO, ZnO and CuO. Among the above main raw materials, especially Fe ₂ O ₃ and ZnO
Has a significant effect on the initial permeability μ i. So usually,
A ferrite core having a desired initial magnetic permeability is manufactured by mixing them in an appropriate ratio.

[0004] In such nickel-zinc type ferrite, as a technique for improving temperature characteristics, an appropriate amount of cobalt oxide or silicon oxide is added.
The “improvement of temperature characteristics” described here means “to minimize the amount of change in initial magnetic permeability between certain predetermined temperatures”.

[0005]

However, although the conventional method of adding cobalt oxide or the like improves the temperature characteristics,
There is a drawback that the initial magnetic permeability at room temperature decreases. Considering that the winding parts are naturally downsized as the circuit is downsized, lowering the initial magnetic permeability is disadvantageous for downsizing.
Therefore, it is desirable that the temperature characteristics can be improved without deteriorating the initial magnetic permeability.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method capable of improving the temperature characteristics of nickel-zinc system ferrite without deteriorating the initial magnetic permeability.

[0007]

The present invention, which can achieve the above objects, provides a nickel-based alloy having a composition generally used in the past.
This is a method in which an extremely small amount of indium oxide (In ₂ O ₃ ) is added to a zinc-based ferrite material, and then firing is performed. The amount of indium oxide added is in the range of 0.01 to 0.2% by weight with respect to the main component nickel-zinc ferrite material.

The nickel-zinc ferrite material used here has a composition range that is generally used as an oxide magnetic material for inductors, and Fe ₂ O ₃ is 4
The basic composition is 3 to 50 mol%, NiO is 10 to 35 mol%, ZnO is 10 to 35 mol%, and CuO is 3 to 15 wt%. Although it depends on the basic composition of the nickel-zinc ferrite material, the particularly preferable amount of In ₂ O ₃ added is in the range of 0.05 to 0.1% by weight.

[0009]

The addition of In ₂ O ₃ hardly changes the initial magnetic permeability and changes only the temperature characteristics. The reason has not been fully clarified yet, but since the temperature characteristics are affected by the magnetocrystalline anisotropy constant K ₁ of the ferrite, I
The addition of n ₂ O ₃ causes a phenomenon such as a shift in the Fe ⁺³ site distribution, and the K ₁ temperature characteristic becomes gradual.
As a result, it is considered that the temperature characteristic of the initial magnetic permeability also becomes gentle. However, if the amount of In ₂ O ₃ added is too large, the temperature characteristics are deteriorated, which is not preferable. Therefore, In ₂ O
The addition amount of ₃ is in the range of 0.01 to 0.2% by weight, and particularly preferably in the range of about 0.05 to 0.1% by weight.

[0010]

EXAMPLES In ₂ O ₃ in the range of 0 to 0.2 wt% with respect to nickel-zinc ferrite materials of three basic compositions A to C shown in Table 1 (each unit is mol%). Added in
Various types of ferrite cores were produced by firing at a sintering temperature of 1100 ° C., and the initial magnetic permeability and its temperature characteristics were measured.

[0011]

[Table 1]

FIG. 1 shows the relationship between the amount of In ₂ O ₃ added (% by weight) and the relative temperature coefficient α μr (× 10 ⁻⁶ / ° C.) in the basic composition A. The relative temperature coefficient αμr is a value defined by the following equation. αμr = [μi (at 60 ° C) -μi (at-20 ° C)] / [μi ² (at 60 ° C) × 80 ° C] Relative temperature coefficient when 0.01% by weight or more of In ₂ O ₃ is added αμr begins to decrease and reaches a peak at about 0.1% by weight. After that, as the amount of In ₂ O ₃ added increases, the relative temperature coefficient αμr increases.

[0013] The same basic composition A, the case of In ₂ O ₃ not added, when the In ₂ O ₃ was added 0.05 wt%, for each of the case of adding 0.1 wt%, 2
Temperature coefficient Δμi / μi (%) and temperature (℃) at 0 ℃
The result of obtaining the relationship with is shown in FIG. Than in the case of In ₂ O ₃ not added, if the In ₂ O ₃ was added 0.05 wt% or 0.1 wt%, it can be seen that the temperature characteristics are improved.

FIG. 3 shows the relationship between the added amount (% by weight) of In ₂ O ₃ and the relative temperature coefficient αμr (× 10 ^-6 / ° C.) in the basic compositions B and C. Also in this case, as in the case of FIG.
_If 0.01% by weight or more of ₂ O ₃ is added, the relative temperature coefficient α
μr begins to decrease and reaches a peak at about 0.1% by weight. It can be seen that the relative temperature coefficient αμr also increases as the amount of In ₂ O ₃ added thereafter increases.

As a result of these, the range of the amount of In ₂ O ₃ added is preferably 0.01 to 0.2% by weight, but particularly preferably 0.
The range of 05 to 0.1% by weight is preferable.

FIG. 4 shows the relationship between the amount of In ₂ O ₃ added (% by weight) and the initial magnetic permeability μi in each of the basic compositions A to C.
In any case, the initial magnetic permeability μi did not change regardless of the addition of In ₂ O ₃ .

[0017]

As described above, the present invention is a method of adding a small amount of indium oxide to nickel-zinc type ferrite and firing it. Therefore, the temperature characteristic of the initial magnetic permeability is improved without lowering the initial magnetic permeability. it can. Therefore, there is an advantage that it can be easily combined with a chip capacitor having good temperature characteristics. Further, as described above, since the initial magnetic permeability does not decrease, it is possible to contribute to the miniaturization of the winding parts and the miniaturization of the circuit.

[Brief description of drawings]

FIG. 1 is a graph showing an example of the relationship between the amount of In ₂ O ₃ added and the relative temperature coefficient αμr.

FIG. 2 is a graph showing an example of the relationship between ambient temperature and Δμi / μi.

FIG. 3 is a graph showing another example of the relationship between the amount of In ₂ O ₃ added and the relative temperature coefficient αμr.

FIG. 4 is a graph showing the relationship between the amount of In ₂ O ₃ added and the initial magnetic permeability.

Claims (2)

(57) [Claims] 1. Fe ₂ O ₃ 43 to 50 mol%, NiO
10-35 mol%, ZnO 10-35 mol%, CuO
In ₂ O ₃ is added in an amount of 0.01 to 0.2 with respect to a nickel-zinc ferrite material having a basic composition of ₃ to 15 mol%.
Nickel characterized by adding weight% and firing
Method for producing zinc-based ferrite. 2. The amount of In ₂ O ₃ added is 0.05 to 0.1.
The manufacturing method according to claim 1, wherein the weight percentage is set.