KR20160035514A - Magnetic material and their manufacturing method - Google Patents

Abstract

The present invention relates to a magnetic material and a manufacturing method thereof. The manufacturing method of a magnetic material distributes and mixes hexaferrite micropowder of a plate shape and a condensed body formed by condensing the hexaferrite micropowder of a plate shape by a proper heat treatment in a resin to manufacture a magnetic material which satisfies high permeability and low permeability loss at the same time.

Description

[0001] Magnetic materials and their manufacturing methods [0002]

The present invention relates to a magnetic material and a method of manufacturing the same.

Recently, with the progress of miniaturization, high speed and high frequency of electronic devices, electronic components used in these electronic devices are required to be miniaturized and high efficiency characteristics in a high frequency band of several hundred MHz to several GHz.

To this end, a technique has been proposed in which spinel ferrite such as Mn-Zn ferrite or Ni-Zn ferrite is used to miniaturize an antenna while maintaining gain. However, since the spinel ferrite has a high permeability in a low frequency band and a high permeability in a high frequency band of several hundred MHz or more, the permeability is rapidly lowered due to the Snoek's limit, so that it is difficult to use the spinel ferrite as a magnetic material for high- .

Hexa type magnetic materials having high magnetic permeability at high frequencies beyond the threshold of spinel ferrites have been studied. However, magnetic permeability of the hexagonal magnetic material is also drastically decreased at high frequency ranges of 1 GHz or more .

Therefore, research on magnetic materials that can satisfy both high permeability and low investment loss at high frequency bands above 1 GHz is required.

Korean Patent Publication No. 2010-0039233

It is an object of the present invention to provide a magnetic material having a high permeability and a low investment loss suitable for a high frequency band of GHz or higher in manufacturing a magnetic material used for an antenna of a high frequency band.

The above object of the magnetic material according to the present invention can be attained by mixing plate-like hexaferrite fine powder and agglomerate formed by coagulation of the plate-like hexaferrite fine powder and dispersing them in the resin. At this time, the plate-like hexaferrite fine powder may have a size of 2 mu m or less having a single magnetic domain, and the aggregate may be formed to have a size of 5 mu m to 100 mu m.

When the magnetic material contained in the magnetic material is constituted only by plate-like hexaferrite powder having a size of 2 탆 or less, a semi-magnetic field is formed on the surface of the fine powder to decrease the magnetic permeability of the magnetic material, and the magnetic material contained in the magnetic material is composed only of the aggregate The magnetic permeability of the magnetic material decreases as the filling ratio of the magnetic material decreases due to the large pores between the agglomerates. Therefore, the hexagonal ferrite fine powder is agglomerated through a suitable heat treatment to form agglomerates, which can be used together with the fine powder have.

The plate-like hexaferrite fine powder is dispersed while filling the space between the aggregates, and the aggregate can be formed by aggregating the plate-like hexaferrite fine powder without deforming the shape.

Another object of the present invention is to provide a process for producing a hexaferrite fine powder, which comprises preparing a raw material of a hexaferrite fine powder in a plate form, mixing and heat-treating the raw material to form a plate hexaferrite fine powder or an aggregate, And a step of drying and a step of dispersing and mixing the dried plate-like hexaferrite fine powder and aggregate in the resin.

In order to form the plate-like hexaferrite fine powder and the aggregate together, the heat treatment may be carried out at a temperature of 950 ° C. or more and less than 1,100 ° C., and the ratio of the plate-like hexaferrite fine powder formed to the heat treatment temperature and the aggregate is 1: 9 to 3 : May be seven.

The magnetic material according to the present invention can simultaneously satisfy high permeability and low investment loss in a high frequency band of GHz or higher by mixing plate-shaped hexaferrite fine powder and aggregate formed by aggregating plate-shaped hexaferrite fine powder.

Further, it is possible to manufacture an antenna that simultaneously satisfies the miniaturization, the high efficiency, and the broadening characteristic in the GHz band.

1 is a cross-sectional view of a magnetic material according to an embodiment of the present invention
2 is a SEM photograph of aggregates according to an embodiment of the present invention
3 is a process diagram showing a method of manufacturing a magnetic material according to an embodiment of the present invention
4A is a SEM photograph of a magnetic material according to Comparative Example 1 of the present invention
4B is a SEM photograph of a magnetic material according to an embodiment of the present invention.
4C is a SEM photograph of the magnetic material according to Comparative Example 2 of the present invention
5A is a graph showing permeability values measured according to Comparative Examples and Examples of the present invention
5B is a graph showing the investment loss values measured according to the comparative example and the embodiment of the present invention

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as excluding the presence or addition of the mentioned forms, numbers, steps, operations, elements, elements and / It is not.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In this specification, the terms first, second, etc. are used to distinguish one element from another, and the element is not limited by the terms.

Magnetic material

The magnetic material according to an embodiment of the present invention includes a matrix resin and a plate-like hexaferrite fine powder dispersed and mixed in the matrix resin and an aggregate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a magnetic material according to an embodiment of the present invention, and FIG. 2 is a SEM photograph of an aggregate according to an embodiment of the present invention. In addition, the components of the drawings are not necessarily drawn to scale; for example, the dimensions of some of the components of the drawings may be exaggerated relative to other components to facilitate understanding of the present invention.

1 and 2, a magnetic material 100 according to an embodiment of the present invention includes a cohesive body 120 in which plate-shaped hexaferrite fine powder 110, plate-shaped hexaferrite fine powder are aggregated, and a binder and a matrix resin 130 used as a binder.

The plate-like hexaferrite fine powder 110 is a bivalent transition metal such as barium Ba or strontium (Sr), nickel (Ni), cobalt (Co), manganese (Mn), zinc (Zn) Element and trivalent iron oxide.

These compounds can form various crystal structures such as M-type, Y-type, W-type, Z-type, X-type and U-type depending on the chemical composition. Can be used.

When the hexaferrite fine powder is formed in the form of a plate, the magnetic anisotropy is increased to increase the resonance frequency. Therefore, the investment loss occurring in the high frequency band higher than GHz can be reduced. For this purpose, the hexagonal ferrite powder And may be formed to have a size of 2 mu m or less.

In general, as the size of the plate-like hexaferrite fine powder 110 increases, the magnetic permeability increases. However, when the size of the hexaferrite fine powder 110 increases, an investment loss occurs due to the magnetic domain wall motion phenomenon. It is appropriate that the size of the ferrite fine powder 110 is formed to be 2 mu m or less with a single magnetic domain.

However, when the magnetic material contained in the magnetic material 100 is composed only of the plate-like hexaferrite fine powder 110 having a thickness of 2 μm or less, a demagnetizing field is formed on the surface of the fine powder 100, The plate-like hexaferrite fine powder 110 is agglomerated through a suitable heat treatment to form an aggregate 120, which can be used together with the fine powder.

The aggregate 120 is formed by aggregating plate-shaped hexaferrite powder 110, and is distinguished from a case where one powder is simply large in size. As shown in FIG. 2, each of the aggregates 120 The plate-like hexaferrite fine powder 110 can be aggregated without deformation of the original shape to form the aggregate 120.

When the magnetic material included in the magnetic material 100 is constituted by only the aggregate 120, the size of the aggregate 120 is 5 μm to 100 μm. When the magnetic material included in the magnetic material 100 is composed of the aggregate 120, The permeability of the magnetic material 100 is lowered as the filling rate is lowered.

Therefore, in order to reduce the voids between the aggregates 120 and to improve the fill factor, a plate-like hexaferrite fine powder 110 having a size of 2 μm or less may be mixed with the aggregate 120. In this case, the permeability of the magnetic material 100 becomes higher as the filling ratio of the plate-like hexaferrite powder 110 is filled between the aggregates 120.

In addition, by using the aggregate 120 in which a plurality of plate-like hexaferrite fine powders 110 are aggregated instead of one powder having a large size, the fine powder 110 and the combination of the fine powders 110 having a single magnetic domain with the aggregate 120 So that the investment loss due to the migration of the magnetic domain wall of the fine powder does not occur.

Therefore, the magnetic material 100 can satisfy both high permeability and low investment loss, and through this, it is possible to manufacture an antenna that simultaneously satisfies miniaturization, high efficiency, and wide bandwidth characteristics in a high frequency band above GHz.

On the other hand, the matrix resin 130 in which the plate-like hexaferrite fine powder 110 and the aggregate 120 are dispersed may be a thermosetting resin or a thermoplastic resin. As the thermosetting resin, an epoxy resin, a phenol resin, a polyimide, and a diallyphthalate resin can be used. As the thermoplastic resin, a polyphenylene sulfide, a polyamide, a polyethylene, a polyimide, a polysulfone, a polyetheretherketone, Can be used.

Method of manufacturing magnetic material

3 is a process diagram showing a method of manufacturing a magnetic material according to an embodiment of the present invention.

A method of manufacturing a magnetic material according to an embodiment of the present invention may be configured as follows.

A step (S310) of preparing a raw material of a hexagonal ferrite fine powder and a step (S310) of preparing a raw material of the hexagonal ferrite fine powder by mixing and heat-treating the raw material to form an aggregate with the hexagonal ferrite powder (S320) A step of drying (S330), and a step of dispersing and mixing them in a resin (S340).

In step S310 of preparing the raw material of the plate-like hexaferrite fine powder, a raw material such as acicular iron oxide (Fe ₂ O ₃ ), cobalt oxide (CoO), zinc oxide (ZnO), barium carbonate (BaCO ₃ ) Solid phase powder can be prepared. At this time, the size of the raw material powder is preferably 1 m or less.

When the raw materials are prepared, they are mixed through a dry method or a wet method, and are heat-treated to form aggregates of plate-like hexaferrite fine powders and agglomerated fine powders (S320). The heat treatment temperature is about 950 ° C or more and less than 1,100 ° C. When the temperature is in the above temperature range, both the plate-like hexaferrite fine powder 110 and the aggregate 120 can be formed.

If the heat treatment temperature is lower than 950 ° C., most of the plate-like hexaferrite powder 110 is formed and the aggregate 120 is hardly formed. When the heat treatment temperature is 1,100 ° C. or higher, almost all of the hexaferrite powder 110 is formed of the aggregate 120 .

However, when the magnetic material contained in the magnetic material 100 is composed only of the hexaferrite fine powder 110 in the form of plate without the aggregate 120, a demagnetizing field is formed on the surface of the fine powder, When the magnetic material is composed only of the aggregate 120, the filling rate is lowered due to the large gap between the aggregates 120, and the magnetic permeability of the magnetic material 100 is reduced.

Accordingly, by setting the heat treatment temperature to 950 ° C. or more and less than 1,100 ° C., the plate-like hexaferrite fine powder 110 and the aggregate 120 can be formed together. At this time, the plate-like hexaferrite powder 110 and the aggregate 120 May be mixed and mixed at a ratio of 1: 9 to 3: 7 depending on the heat treatment temperature.

Alternatively, the plate-like hexaferrite fine powder 110 may be formed first by setting the heat treatment temperature to 950 DEG C or lower, and the aggregate 120 may be formed at a temperature of 1,100 DEG C or higher to form plate-shaped hexaferrite fine powder ( 110) and the aggregate (120) may be used in combination.

The plate-like hexaferrite fine powder 110 has a size of 2 μm or less. In general, the permeability increases as the size of the plate-like hexaferrite fine powder 110 increases. However, when the size of the hexaferrite fine powder 110 is large, It is appropriate that the size of the plate-like hexaferrite fine powder 110 is formed to a size of 2 mu m or less having a single magnetic domain.

The size of the agglomerate 120 is 5 to 100 占 퐉 and the large space between the agglomerates 120 is filled with the hexagonal ferrite powder 110 of 2 占 퐉 or less in plate size, The magnetic permeability of the magnetic material 100 can be increased.

When the plate-like hexaferrite fine powder 110 and the aggregate 120 are formed, they are washed with about 3% hydrochloric acid and dried (S330) in order to remove impurities. Then, dispersed and mixed in the resin (S340), thereby producing the magnetic material 100 in which the plate-like hexaferrite fine powder 110 and the aggregate 120 are mixed.

At this time, a thermosetting resin or a thermoplastic resin can be used as the resin. As the thermosetting resin, an epoxy resin, a phenol resin, a polyimide, and a diallyphthalate resin can be used. As the thermoplastic resin, a polyphenylene sulfide, a polyamide, a polyethylene, a polyimide, a polysulfone, a polyetheretherketone, Can be used.

When a thermosetting resin is used, a composite material is prepared by mixing a plate-like hexaferrite powder 110, an aggregate 120 and a resin 130, using a press mold, and heat- And cured. At this time, the composite material is manufactured in a toroidal shape, and the permeability (μ) and the investment loss (tanδ) of the composite material can be measured through a network analyzer.

On the other hand, when a thermoplastic resin is used, it can be formed into a sheet form. The slurry is prepared by mixing the plate-like hexaferrite powder 110, the aggregate 120 and the resin 130, casting (about 100 탆), and then dried. Then, about 10 to 20 dried sheets are laminated, and rolling is carried out using a rolling mill.

At this time, if the thickness of the sheet is reduced through rolling, the density of the sheet is increased and the permeability can be increased. Then, a toroidal specimen can be manufactured using a rudder, and permeability (μ) and investment loss (tanδ) can be measured through a network analyzer.

The amount of the thermosetting resin or the thermoplastic resin is preferably 5 wt% to 10 wt% with respect to the total amount. When the amount of the resin 130 is more than 10 wt%, the packing ratio of the hexaferrite fine powder 110 and the aggregate 120 is lowered, so that a semi-permanent length is formed between the powder and the magnetic permeability.

When the amount of the resin 130 is less than 5 wt%, it is difficult to maintain the shape of the composite because the resin 130 can not fix the hexaferrite fine powder 110 and the aggregate 120 in a plate form.

Comparative Example 1: Flaky Hexaferrite Differential word only  Manufacture of the constituted magnetic material

1) the size of the iron oxide powder of the solid bed type or less _{1㎛ (Fe 2 O 3) 65.0wt} %, cobalt oxide (CoO), 8.5wt%, zinc (ZnO) 2.5wt% oxide, barium carbonate (BaCO ₃₎ 24.0wt %, And mix by dry method.

2) The mixed powder is heat-treated at 920 ° C. for 3 hours to form plate-shaped hexaferrite fine powder of 2 μm or less.

3) The plate-like hexaferrite fine powder is washed with hydrochloric acid (3%) to remove impurities and dried.

4) After drying, the mixture is dispersed and mixed in an epoxy resin, and a composite is formed using a press mold, followed by heat treatment (at 150 ° C) to harden it. At this time, the composite is formed in a toroidal shape.

5) The permeability (μ) and the investment loss (tan δ) of the composite are measured by a network analyzer.

Comparative Example 2: Production of magnetic material composed only of agglomerates

1) the size of the iron oxide powder of the solid bed type or less _{1㎛ (Fe 2 O 3) 65.0wt} %, cobalt oxide (CoO), 8.5wt%, zinc (ZnO) 2.5wt% oxide, barium carbonate (BaCO ₃₎ 24.0wt %, And mix by dry method.

2) The mixed powder is heat-treated at 1,100 ° C. for 3 hours to form agglomerates of 5 μm to 100 μm in which plate-shaped hexaferrite fine powder of 2 μm is agglomerated.

3) The aggregates are washed with hydrochloric acid (3%) to remove impurities and dried.

4) After drying, the mixture is dispersed and mixed in an epoxy resin, and a composite is formed using a press mold, followed by heat treatment (at 150 ° C) to harden it. At this time, the composite is formed in a toroidal shape.

5) The permeability (μ) and the investment loss (tan δ) of the composite are measured by a network analyzer.

Example: Flaky Hexaferrite With fine powders  Manufacture of magnetic materials composed of mixed agglomerates

1) the size of the iron oxide powder of the solid bed type or less _{1㎛ (Fe 2 O 3) 65.0wt} %, cobalt oxide (CoO), 8.5wt%, zinc (ZnO) 2.5wt% oxide, barium carbonate (BaCO ₃₎ 24.0wt %, And mix by dry method.

2) The mixed powder is heat-treated at 1,000 ° C. for 3 hours to form 30 vol% of plate-like hexaferrite powder of 2 μm or less and 70 vol% of agglomerates of 5 μm to 100 μm.

3) The plate-like hexaferrite fine powder and agglomerate were washed with hydrochloric acid (3%) to remove impurities and dried.

4) After drying, the mixture is dispersed and mixed in an epoxy resin, and a composite is formed using a press mold, followed by heat treatment (at 150 ° C) to harden it. At this time, the composite is formed in a toroidal shape.

5) The permeability (μ) and the investment loss (tan δ) of the composite are measured by a network analyzer.

An SEM photograph of the magnetic material 100 manufactured through the above process is shown in FIG. 4A is an SEM photograph of a magnetic material (Comparative Example 1) composed of only plate-shaped hexaferrite powder, FIG. 4B is an SEM photograph of a magnetic material (Example) formed by mixing a hexagonal ferrite powder and an aggregate, (Comparative Example 2) composed of only the agglomerate.

A graph showing the permeability (μ) and the investment loss (tan δ) values of the three examples (Comparative Examples 1, 2, and Example) through a network analyzer is shown in FIG. FIG. 5A is a graph showing the values of permeability () measured according to the comparative example and the example of the present invention, and FIG. 5B is a graph showing the values of the investment loss (tan?) Measured according to the comparative example and the example of the present invention .

Referring to FIGS. 4 and 5, it can be seen that the magnetic permeability is the highest in the GHz band region in the case of the magnetic material (embodiment) in which the hexagonal ferrite powder 110 and the aggregate 120 are mixed. This is because the filling ratio is increased by filling the large voids between the aggregates 120 with the plate-like hexaferrite fine powder 110.

On the other hand, in the case of the magnetic material composed of the plate-like hexaferrite fine powder 110 (Comparative Example 1), the magnetic material (Comparative Example 2) composed of only the aggregate 120 and the permeability decreased due to the formation of the semi- The filling rate is lowered due to the large gap between the aggregates 120, and the permeability is decreased.

On the other hand, it can be seen that the investment losses are similarly maintained in the three examples (Comparative Examples 1, 2 and Examples) of less than 0.5. The embodiment of the present invention uses an aggregated body 120 in which a plurality of plate-like hexaferrite fine powders 110 are aggregated instead of one powder having a large size so that investment loss due to the phenomenon of migration of the magnetic domain wall is not generated, Can be improved by 20% or more.

Accordingly, the magnetic material 100 according to the present invention can satisfy high permeability and low investment loss at the same time. Thus, it is possible to manufacture an antenna that simultaneously satisfies miniaturization, high efficiency, and wide bandwidth characteristics in a high frequency band above GHz.

The foregoing detailed description is illustrative of the present invention. It is also to be understood that the foregoing is illustrative and explanatory of preferred embodiments of the invention only, and that the invention may be used in various other combinations, modifications and environments. That is, it is possible to make changes or modifications within the scope of the concept of the invention disclosed in this specification, the disclosure and the equivalents of the disclosure and / or the scope of the art or knowledge of the present invention. The foregoing embodiments are intended to illustrate the best mode contemplated for carrying out the invention and are not intended to limit the scope of the present invention to other modes of operation known in the art for utilizing other inventions such as the present invention, Various changes are possible. Accordingly, the foregoing description of the invention is not intended to limit the invention to the precise embodiments disclosed. It is also to be understood that the appended claims are intended to cover such other embodiments.

100: magnetic material
110: Plateous hexaferrite fine powder
120: aggregate
130: matrix resin

Claims (15)

Matrix resin;
Agglomerates dispersed in the matrix resin;
A plate-like hexaferrite fine powder mixed to fill the gap between the agglomerates;
Wherein the aggregate is formed by coagulating the plate-like hexaferrite fine powder.
The method according to claim 1,
The plate-like hexaferrite fine powder has a crystal structure of any one of M-type, Y-type, Z-type, X-type and U-type.
The method according to claim 1,
The plate-like hexaferrite fine powder has a size of 2 mu m or less and has a single magnetic domain.
The method according to claim 1,
The aggregate is formed by coagulating the plate-like hexaferrite fine powder without deforming the shape.
The method according to claim 1,
Wherein the aggregate has a size of 5 mu m to 100 mu m.
The method according to claim 1,
Wherein the matrix resin is any one of an epoxy resin, a phenol resin, a polyimide, a diallyl phthalate resin, a polyphenylene sulfide, a polyamide, a polyethylene, a polysulfone, a polyetheretherketone, and a polystyrene.
Preparing a raw material of the hexagonal ferrite fine powder;
Mixing and heat-treating the raw materials to form plate-shaped hexaferrite fine powder or agglomerate;
Washing and drying the hexagonal ferrite fine powder and the aggregate; And
Dispersing and mixing the dried plate-like hexaferrite fine powder and agglomerate in a resin;
Magnetic material.
8. The method of claim 7,
In the step of preparing the raw material of the plate-like hexaferrite fine powder,
Wherein the raw material is acicular iron oxide (Fe ₂ O ₃ ), cobalt oxide (CoO), zinc oxide (ZnO), barium carbonate (BaCO ₃ ).
8. The method of claim 7,
In the step of preparing the raw material of the plate-like hexaferrite fine powder,
Wherein the size of the raw material is 1 占 퐉 or less.
8. The method of claim 7,
In the step of mixing and heat-treating the raw materials to form a plate-like hexaferrite fine powder or agglomerate,
Wherein the heat treatment is performed at a temperature of 950 ° C or more and less than 1,100 ° C.
8. The method of claim 7,
In the step of mixing and heat-treating the raw materials to form a plate-like hexaferrite fine powder or agglomerate,
Wherein the ratio of the plate-like hexaferrite fine powder to the aggregate is 1: 9 to 3: 7.
8. The method of claim 7,
In the step of mixing and heat-treating the raw materials to form a plate-like hexaferrite fine powder or agglomerate,
Wherein the plate-shaped hexaferrite fine powder has a size of 2 mu m.
8. The method of claim 7,
In the step of mixing and heat-treating the raw materials to form a plate-like hexaferrite fine powder or agglomerate,
And the size of the aggregate formed is 5 to 100 占 퐉.
8. The method of claim 7,
In the step of mixing and heat-treating the raw materials to form a plate-like hexaferrite fine powder or agglomerate,
Wherein the formed aggregate is agglomerated without deforming the shape of the plate-like hexaferrite fine powder.
8. The method of claim 7,
In the step of dispersing and mixing the dried plate-like hexaferrite fine powder and aggregate into the resin,
Wherein the amount of the resin is 5 wt% to 10 wt% with respect to the total amount.

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