JPH0254902A - Low-loss ferrite - Google Patents

Abstract

PURPOSE:To reduce loss, in particular, in the regions above 100kHz by using Fe2O3, ZnO, MnO as main ingredients and a predetermined amount of CaO, SiO2, ZrO2, SnO2 and/or TiO2 as sub-ingredients and by adding them. CONSTITUTION:Main ingredients are 50 to 60mole% Fe2O3 and 10 to 15mole% ZnO. The remaining part is MnO and additives of 0.08 to 0.40mole% CaO, 0.01 to 0.2mole% SiO2, 0.01 to 0.10mole% SiO2 and 0.05 to 1.0mole% SnO2 and/or TiO2. It is subjected to a normal ferrite manufacture and reaction and granulation are performed. After it is molded and pressed, it is sintered at a predetermined O2 partial pressure. With this constitution, a magnetic material having low loss, in particular, in the high-frequency regions above 100kHz can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-loss ferrite used in converter transformers and the like, and particularly relates to a low-loss ferrite that has little loss in a high frequency region.

[Summary of the invention]

The present invention adds CaO and SiO□ to ferrite whose main components are Fezes, ZnO, and MnO, and also adds Z
By adding at least one of rot, SnO, and TtO, it is intended to reduce the loss particularly in the high frequency region of 100kt(z or higher).

[Conventional technology]

In converter lances for switching power supplies, a switching frequency of about 100 kHz or less has been used so far, and the low loss ferrite that should be compatible with this is Mn-Zn ferrite with a subcomponent of 0.04 to 0. .005 to 0.2% CaO and 0.005 to 0.
Ones containing 1% SiOz have already been used.

However, in recent years, there has been an increasing demand for switching power supplies to be used at high frequencies of 100kHz or higher in order to make them smaller and lighter.
When used as a converter transformer material for the above-mentioned switching power supplies, a problem arises in that the loss is large and heat is generated.

[Problem to be solved by the invention]

Therefore, ferrite materials for future converter transformers will have a frequency of 100 to 500 kHz.

Temperature 80~100°C1 large amplitude excitation (1000~200°C
Low loss is required even under conditions of 0 Gauss).

Therefore, the present invention has been proposed in view of the above-mentioned conventional situation, and fully satisfies the characteristics required for rice grain for converter transformers, and in particular,
It is an object of the present invention to provide a low-loss ferrite that can reduce loss even in a high frequency region of Hz or higher.

[Means to solve the problem]

As a result of intensive research to achieve the above-mentioned objective, the inventors of the present invention discovered that ZrO and S
They discovered that it is effective to add both nOx and TrOx, and completed the present invention.
etos 50-60 mol%, ZnO 10-15 mol%
, the remainder is MnO as a main component, and Ca 00. as a subcomponent.
08-0.40 mol%, Sin.

0.01-0.2 mol%, Zr Ozo, 01
~0.10 mol%, SnO, and/or T i Ozo
, 05 to 1.0 mol%.

The main components, FetO, ZnO, and MnO, are naturally constrained to the above-mentioned ranges as their compositions have soft magnetic properties, but especially when it comes to ZnO, a saturation magnetic flux density of about 5ooo is desired because it is excited with a large amplitude. , magnetic permeability, temperature characteristics of core loss, etc., here 10 to 1
For example, in magnetic head materials, the composition differs depending on whether saturation magnetic flux density or magnetic permeability is important, and since there is no boundary, the composition range of ZnO is wide. It's different.

CaO and 5ift are added from the viewpoint of normal low magnetic loss, and the amount of addition thereof is determined from the viewpoint of low magnetic loss characteristics.

On the other hand, Zr0t, S n Ox, and T i Ox are added from the viewpoint of reducing loss of one member, especially at high frequencies. That is, ZrOx suppresses grain growth and reduces the loss of one member at high frequencies, and Snow and Ti0z are dissolved in the crystal lattice of ferrite, resulting in F e '',=!
Electron transfer such as F e ''+ e is reduced, resulting in an increase in the resistivity of crystal grains, and the eddy current is reduced.

Therefore, these ZrO, and S n O! , T i
If the amount of Ox added is below the above range, the desired effect (low loss in the high frequency range) cannot be expected. On the other hand, if the amount added is too large, the magnetic properties will be affected, so the amount is set within the above-mentioned range.

In addition, ferrite used in magnetic head materials etc. is required to have a high density (for example, 99% or more) and therefore requires hot isostatic pressing treatment (so-called HIP treatment). For ferrite, extremely low density is undesirable because it leads to a decrease in saturation magnetic flux density.
A normally obtained level (approximately 95% or more) is sufficient, and the above-mentioned HIP treatment is not necessary.

[Example] The present invention will be explained below based on specific experimental results.

Fe, O, ZnO, MnO, Cab, 5iOz.

Mix ZrO□ and SnO in the proportions shown in Table 1,
After reaction, granulation, and molding press according to the usual ferrite manufacturing method, low-loss Mn-Zn ferrite was obtained by firing at 2% oxygen partial pressure and 1250"C. It is shown in Table 1.

(The following is a margin) Table 1 Table 2 For each sample obtained, the core loss Wc was measured at a temperature of 100°C and a maximum magnetic flux density B m of 1000 Gauss. The results are shown in Table 2.

From this Table 2, it can be seen that the core loss of the product doped with ZrO or 5nO1 is smaller than that of the non-additive product in the frequency range of 100 kl (z or higher). It was also confirmed that the core loss was smaller when both were added at the same time than when both were added.

In particular, the product with 0.05 mol% of ZrO and 0.3 mol% of Snow added has a 200k
Core loss at frequencies above Hz is reduced by more than 10%.

Note that other magnetic properties were hardly changed by these additions.

The case where ZrO and SnO are used together has been described above, but when ZrO and TiOz or Zrot and Sn
When similar experiments were conducted using both ug and TiOt, a reduction in core loss in the high frequency range was observed.

It fully satisfies the electrical characteristics required as a material for a converter transformer, and is especially suitable for 100K.
It is possible to achieve low loss in a high frequency region of Hz or higher.

Therefore, by using the low-loss ferrite of the present invention as a material for a high-frequency converter transformer, it is possible to reduce the size and weight of a switching power supply.

Claims (1)

[Claims] Fe_2O_350-60 mol%. ZnO10-15
mol%, the remainder is MnO as the main component, CaO0.08 to 0.40 mol%, SiO as subcomponents.
_20.01~0.2 mol%, ZrO_20.01~0
．． 10 mol%, SnO_2 and/or TiO_20.0
A low loss ferrite characterized by containing 5 to 1.0 mol%.