JPH07211535A - Method of manufacturing mn-zn based ferrite - Google Patents

Abstract

PURPOSE:To obtain a material having high magnetic permeability up to high frequency (to 500kHz) and a lower loss. CONSTITUTION:In Mn-Zn based ferrite, CaO 0.05 to 0.12wt.%, Bi2O3 0.04wt.% or less (however unincluding 0wt.%), and SiO2 0.01 to 0.02wt.% (however unincluding 0.01wt.%) are included to burn under burning conditions exceeding oxygen concentration 1% at 1350 to 1380 deg.C, having high frequency and high initial magnetic permeability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an M having high permeability and high magnetic permeability.
It is an object to provide a manufacturing method for obtaining an n-Zn ferrite.

[0002]

2. Description of the Related Art Mn--Zn type ferrite having a high magnetic permeability is mainly composed of Fe2O3, ZnO and MnO, and various additives (Bi, Ca,
It was a material to which V) was added.

This Mn--Zn type ferrite is used as a magnetic core of a transformer, a noise filter, etc., and miniaturization of parts is being promoted by utilizing its high magnetic permeability characteristics.

[0004]

For example, as a magnetic core for a noise filter, there has been an increasing demand for a material having a high magnetic permeability up to a high frequency (up to 500 kHz).

However, in the case of the conventional Mn-Zn type ferrite, there is a problem that the frequency characteristic of magnetic permeability is poor, the magnetic permeability decreases at high frequencies, and the loss at high frequencies increases.

In view of the above, it is an object of the present invention to obtain an Mn-Zn type ferrite having high magnetic permeability and high frequency.

[0007]

According to the present invention, CaO is added as an auxiliary component in an Mn--Zn system ferrite in an amount of 0.05 to 0.05.
0.12 wt%, Bi2O3 is 0.04 wt% or less (however, 0 wt% is not included), and SiO2 is 0.01 to 0.
02 wt% (not including 0.01 wt%), firing temperature 1350 to 1380 ° C., firing under firing conditions exceeding 1% oxygen concentration, and μi ≧ 500 at 100 kHz.
It is intended to obtain Mn—Zn based ferrite with μi ≧ 4000 at 0 and 500 kHz.

In the present invention, the reason for limiting the amounts of subcomponents is that when CaO, Bi2O3, and SiO2 are less than a predetermined amount, the loss increases, and when CaO is more than the predetermined amount, the magnetic permeability decreases and Bi2O3 and SiO2 are present. This is because if the amount is larger than the fixed amount, abnormal sintering will occur, which is not preferable.

[0009]

Examples Fe2O3 53 mol%, MnO 27 mol%, ZnO 20 mol% were the main components, and CaO,
A raw material containing Bi2O3 and SiO2 in the amounts shown in Table 1 was prepared, calcined at 850 ° C. for 2 hours, crushed with a ball mill for 8 hours, and compression-molded into a ring shape.
Baking was carried out at 5 ° C. for 5 hours at an oxygen concentration of 5%. In addition, each sample was prepared by changing the baking conditions (baking temperature, baking atmosphere) in the same sample manufacturing process as in the example. 100kH of the core
z and initial permeability μi of 500 kHz, t at 100 kHz
Let an δ / μi and μi at 100 kHz be A, and
When μi at 0 kHz is B, the initial permeability μ at 500 kHz with respect to 100 kHz represented by (A−B) / A.
Table 1 shows the change rate Δi / μi of i. In Table 1, those within the range of the present invention are examples, and those outside the range are comparative examples.

[0010]

[Table 1]

Further, the frequency characteristics of magnetic permeability of the example (Sample No. 8) and the comparative example (Sample No. 10) are shown in FIG. As shown in FIG. 1 and Table 1, it is understood that the examples of the present invention are materials having high magnetic permeability even at high frequencies. At the same time, it can be seen that the material has low loss.

Further, CaO, Bi2O3 and Si contained
O2 is 0.05 to 0.12 wt% CaO, Bi2O
3 is 0.04% by weight or less (not including 0% by weight), and SiO2 is 0.01 to 0.02% by weight (however,
It was found that the characteristics similar to those of the examples shown in Table 1 can be obtained within the range of 0.01% by weight).

However, if the firing temperature is in the range of 1350 to 1380 ° C., the oxygen concentration at that time must exceed 1%. When the oxygen concentration is 1% or less, the initial magnetic permeability at a frequency of 500 kHz decreases and the relative loss coefficient tan δ.
/ Μi increases.

[0014]

According to the present invention, it is possible to obtain a Mn-Zn ferrite having a high magnetic permeability up to a high frequency and a small loss even at a high frequency.

[Brief description of drawings]

FIG. 1 is a frequency characteristic of magnetic permeability of an example according to the present invention and a comparative example.

Claims (1)

[Claims] 1. A Mn—Zn-based ferrite containing 0.05 to 0.12% by weight of CaO as a secondary component and Bi2O.
3 is 0.04% by weight or less (however, 0% by weight is not included), and SiO2 is 0.01 to 0.02% by weight (however,
(Not including 0.01% by weight), and the firing temperature is 1350
˜1380 ° C., firing is performed under the firing conditions in which the oxygen concentration exceeds 1%, and the initial magnetic permeability μi is 500 at a frequency of 100 kHz.
A method for producing Mn—Zn ferrite, which is 0 or more and 4000 or more at 500 kHz.