JPH0462908A - Manufacture of low loss oxide magnetic material - Google Patents

Abstract

PURPOSE:To reduce the power loss thus enabling the high-frequency number of a switching power supply to be increased while the title material to be miniaturized and light-weighted by a method wherein silicon silicon, carbide or silicon nitride are added as for SiO2 as the sub component. CONSTITUTION:Within the title low loss oxide magnetic material comprising 30-40mol% of manganese monooxide, 5-15mol% of zinc oxide and the residual mol% of ferric oxide as the main component and 0.04-0.15wt.% of calcium oxide, 0.010-0.l00wt.% of silicon dioxide as the sub component, one kind or mixture of elements out of metallic silicon, silicon carbide, silicon nitride in equal amount to that of the composition of silicon dioxide as the sub component is added.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a low-loss oxide magnetic material.

[Prior art and invention or problem to be solved] Conventionally,
The switching power supply has a driving frequency of ~100 kHz.
However, in recent years, there has been a trend toward an increase in drive frequency due to the demand for smaller size and lighter weight. However, as the driving frequency increases, the power loss also increases, resulting in increased heat generation, and therefore, ferrites with lower loss are required for switching power supplies.

Ferrite for these switching power supplies and (.

The main component is 30 to 40 mol% manganese monoxide (
MnO), 5 to 15 mol% zinc oxide (Zno) and the balance ferric oxide (Fe203).
Zn ferrite is used, and 0.
04-0.15% by weight of calcium oxide (CaO);
0.010 to 0.100% by weight of silicon dioxide is added to reduce loss. However, even higher frequency,
In order to reduce the size and weight, lower loss is required.

Therefore, a technical object of the present invention is to provide a manufacturing method for improving power loss of a low-loss magnetic material used for a switching power supply.

[Means for Solving the Problem] According to the present invention, 30 to 40 mol% manganese monoxide (MnO) and 5 to 15 mol% zinc oxide (Z
n O) and the remainder ferric oxide (Fe2'03
) and 0.04-=O as a subcomponent.

15% by weight of calcium oxide (Cab) and 0.01
0 to 0.1.00% by weight of silicon dioxide (SiO2).

A method for producing a low-loss oxide magnetic material is obtained, which is characterized in that a composition-equivalent amount of any one of silicon metal, silicon carbide, and silicon nitride, or a mixture thereof, is added as silicon dioxide as a subcomponent.

As a result of various studies to improve the power loss of Mn-Zn ferrite, the inventor found that 30% as the main component.
~40 mol% manganese monoxide.

Contains 5 to 15 mol% zinc oxide (ZnO), the remainder ferric oxide (Fe20s), and 0.04 to 0.04% as an accessory component.
and 15% by weight of calcium oxide (Cab).

0.010-0.100% by weight of silicon dioxide (SiO
□) In a low-loss magnetic material containing □, power loss can be reduced more than before by adding silicon dioxide as a subcomponent in the form of a composition-equivalent amount of any one of metal silicon, silicon carbide, and silicon nitride, or a mixture thereof. made possible.

Conventionally, the main components of Mn-Zn ferrite are appropriately selected, the subcomponents are adjusted, and the powder is further adjusted.

By strictly controlling the manufacturing process such as sintering, we are able to adjust the structure and reduce power loss.

Further, the subcomponents CaO and SiO□ are important as grain boundary formers and are known to be necessary components, and therefore they have been added in the form of oxides, hydroxides, and carbonates. However, this is a feature of the present invention. Addition of 5in2 to metallic silicon and silicon carbide.

Alternatively, by using silicon nitride, it is estimated that the power loss is further reduced as follows.

The subcomponent Cab, 5in2 is necessary as a grain boundary formation material, but it is said that it forms a low melting point liquid phase during the sintering process;

This affects the growth of sintered grains, making it difficult to optimally adjust the final structure of the product.

When SiO2 is added as metallic silicon, silicon carbide, or silicon nitride, these are oxidized during the sintering process to form 5i02
It is thought that the structure of the final product is improved and power loss is reduced because the formation of the liquid phase is also delayed.

[Example] Next, embodiments of the present invention will be described with reference to the drawings.

53 powders each of Fe2O3, MnCO3, and ZnO
．． 0 llol%, 35.0 mo1%, 12.
After weighing to give 0 llol%, the mixture was mixed in a ball mill and calcined at about 900°C. This calcined powder contains 0.06% by weight of CaCO3 and 0.0% of SiO2 as subcomponents.
3% by weight equivalent of 1) metallic silicon, 2) silicon carbide, 3
) silicon nitride, 4) metallic silicon and silicon nitride (1:1
) and 5) Five types of powders to which SiO2 was added were prepared. Furthermore, these powders were mixed and ground in a ball mill, spray granulated after adding a binder, and after forming a toroidal core,
Main firing was performed at 00°C. Table 1 shows these 51”lfl
power lower, (100kHz, 200mT
, at 60°C).

Table 1 and Figure 7 show power loss (100kHz, 200mT)
shows the temperature characteristics of From these results, the effect of improving power loss by the present invention can be recognized.

[Effects of the Invention] As described above, according to the two inventions, it is possible to reduce the power loss of low-loss oxide magnetic materials that can be used in switching power supplies, and it is possible to increase the frequency of switching power supplies and make them smaller and lighter. becomes.

[Brief explanation of the drawing]

Figure 1 shows that in an example of the present invention, 8102 equivalent amounts of subcomponents were added to 1) metallic silicon, 2) silicon carbide, 3) silicon nitride, 4) metallic silicon and silicon nitride (1:1)5
) 100kHz of 5 samples when performed with S io2, 2
The temperature characteristics of power loss at 00 mT are compared. The numbers in the figure correspond to the sample numbers in Table 1.

Claims (1)

[Scope of Claims] 1) 30 to 40 mol% manganese monoxide (
MnO), 5 to 15 mol% zinc oxide (ZnO), and
Contains ferric oxide (Fe_2O_3) as the balance, and 0.04-0.15% by weight of calcium oxide (Fe_2O_3) as an accessory component.
In a low-loss oxide magnetic material containing silicon dioxide (SiO_2) in an amount of 0.010 to 0.100% by weight, an equivalent amount of metallic silicon,
A method for producing a low-loss oxide magnetic material, characterized by adding one of silicon carbide and silicon nitride, or a mixture thereof.