KR20150128048A - Ferrite sheet and magneto dielectric antenna using the same - Google Patents

Ferrite sheet and magneto dielectric antenna using the same Download PDF

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Publication number
KR20150128048A
KR20150128048A KR1020140054781A KR20140054781A KR20150128048A KR 20150128048 A KR20150128048 A KR 20150128048A KR 1020140054781 A KR1020140054781 A KR 1020140054781A KR 20140054781 A KR20140054781 A KR 20140054781A KR 20150128048 A KR20150128048 A KR 20150128048A
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ferrite sheet
powder
hexaferrite
type
present
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KR1020140054781A
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Korean (ko)
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김학관
나은혜
김진모
서정욱
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삼성전기주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/0302—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity characterised by unspecified or heterogeneous hardness or specially adapted for magnetic hardness transitions
    • H01F1/0311—Compounds
    • H01F1/0313—Oxidic compounds
    • H01F1/0315—Ferrites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/086—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together sintered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/08—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers
    • H01F10/10—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support

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  • Power Engineering (AREA)
  • Magnetic Ceramics (AREA)
  • Soft Magnetic Materials (AREA)

Abstract

The present invention relates to a ferrite sheet and a magnetic antenna using the same. According to the present invention, the ferrite sheet comprises: a binder; and a hexagonal plate shaped ferrite powder aligned in a surface direction. As such, the purpose of the present invention is to provide the ferrite sheet having high permeability and low permeability. Moreover, another purpose of the present invention is to have the ferrite sheet having high permeability and low permeability to be minimized and have high efficiency and broadbanding properties.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a ferrite sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic body technology, and more particularly, to a ferrite sheet and a magnetic body antenna using the ferrite sheet.

In recent years, along with downsizing, high-speed, and high-frequency electronic devices, electronic components used in these electronic devices have been demanded for high-efficiency characteristics in a frequency band of several hundred MHz to several GHz with miniaturization.

To this end, a technique has been proposed in which spinel ferrites such as NiZn-based ferrite are used to miniaturize an antenna while maintaining gain. But, Spinel ferrites have a high magnetic permeability in a low frequency band, but the permeability is rapidly lowered due to the Snoek's limit in a high frequency band of several hundred MHz or more, and thus it is difficult to use them as magnetic materials for high frequency electronic parts.

Hexa type magnetic materials having a high permeability even in a high frequency band beyond the threshold of spinel ferrite have been studied. However, the magnetic permeability of the hexa-type magnetic material also decreases sharply in the high frequency band exceeding 1 GHz It is known.

Therefore, research on magnetic materials capable of satisfying high permeability and low investment loss simultaneously in a high frequency band of 1 GHz or more is required.

Japanese Patent Application Laid-Open No. 2009-027145

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems and disadvantages encountered in conventional antennas for high frequency bands, and it is an object of the present invention to provide a high- A ferrite sheet is provided.

Another object of the present invention is to provide a ferromagnetic material having a ferrite sheet having a high permeability and a low investment loss and simultaneously satisfying both miniaturization, high efficiency, and wide band characteristics in a high frequency band above GHz.

The above object of the present invention is achieved by providing a ferrite sheet containing hexaferrite powder in the form of a hexagonal plate-like hexagonal plate and a binder.

The ratio of the thickness of the hexaferrite powder to the particle size may be from 30: 1 to 4: 1. (The particle size of the powder is defined as the maximum diagonal length, and the thickness is defined as the average thickness between the maximum thickness and the minimum thickness.)

The degree of planar alignment of the hexaferrite powder may be 50% or more.

The filling ratio of the hexaferrite powder in the ferrite sheet may be 70 to 93%.

The hexaferrite powder may have any one of a crystal structure selected from Y type, Z type, M type, W type, X type and U type.

The hexaferrite powder may be represented by the following formula (1).

≪ Formula 1 >

Ba 1-x Sr x Co 1-y [Me] y Fe m O n

X, y <1, 12 <m <36 and 19 <n <60), where [Me]

The Y-type hexaferrite powder may be represented by the following formula (2).

(2)

1] x Sr x Co 1-y [Me] y Fe 12 O 22 wherein [Me] is one selected from Zn, Mn and Cu and 0 <x, y <

The average particle size of the hexaferrite powder may be 1.5 탆 or less.

The ferrite sheet may have a permeability (μ) of 1.8 or more and an investment loss (tan δ) of 0.05 or less in the frequency band of 2.1 GHz.

The density of the ferrite sheet may be 4.3 or less.

Another object of the present invention is achieved by providing a magnetic antenna having a permeability (μ) of 1.8 or more and an investment loss (tan δ) of 0.05 or less in a frequency band of 2.1 GHz.

The ferrite sheet according to the present invention comprises By controlling the plane magnetic anisotropy and filling rate of the hexagonal plate hexaferrite powder, a high permeability of 1.8 or more and a low investment loss of 0.05 or less can be satisfied in a high frequency band of 1 GHz or more.

Further, since the ferrite sheet according to the present invention is manufactured in a dry state rather than a sintered body and is given a flexibility with a density of 4.3 or less, it is suitable for a magnetic material of an electronic part which is required to have flexibility because of its excellent formability, The occurrence of debris at an edge portion at the time of sheet cutting of the sheet can be suppressed and the reliability of the product can be improved.

The present invention also provides a ferrite sheet having a high permeability and a low investment loss in a high frequency band of 1 GHz or more, and it is possible to manufacture a magnetic antenna that simultaneously satisfies miniaturization, high efficiency, and wide band characteristics in a high frequency band of 1 GHz or more.

1 is a cross-sectional view of a ferrite sheet according to an embodiment of the present invention.
2 is a partially enlarged perspective view of the hexaferrite powder of FIG.
FIG. 3 is a graph showing X-ray diffraction analysis patterns of hexagonal plate-shaped Ba 2 Co 2 Fe 12 O 22 sintered powders used in the present invention by calcination temperature.
4 is a view for explaining the magnetic direction of the hexaferrite powder according to the embodiment of the present invention.
5 is a cross-sectional view of a ferrite sheet according to another embodiment of the present invention.
6 is an SEM photograph showing the microstructure before and after the aligning step of the ferrite sheet according to Example 1 of the present invention.
7 is a TEM micrograph of a Ba 2 Co 2 Fe 12 O 22 powder used in an embodiment of the present invention.
8 is a graph showing permeability and investment loss characteristics according to the frequencies of Examples 1 to 5 and Comparative Example of the present invention.

The matters relating to the operational effects including the technical structure of the ferrite sheet and the magnetic antenna according to the present invention for the above object will be clearly understood by the following detailed description of the preferred embodiments of the present invention with reference to the drawings.

Hereinafter, the ferrite sheet and the magnetic substance antenna according to the present invention will be described in detail.

FIG. 1 is a cross-sectional view of a ferrite sheet according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of a hexaferrite powder of FIG. 1, showing an ideal state.

1, the ferrite sheet 100 according to an exemplary embodiment of the present invention may be manufactured in the form of a sheet having hexagonal ferrite powder 110 and a binder 120.

The hexaferrite powder 110 may be a hexaferrite powder having a hexagonal plate-like crystal structure as shown in FIG.

Referring to FIG. 2, when the ratio of the thickness h to the particle size d of the hexaferrite powder 110 is defined as an aspect ratio, the hexaferrite powder in hexagonal plate- It is desirable to have an aspect ratio in the range of 4: 1.

Here, the particle size d can be defined as the maximum diagonal length, and the thickness h can be defined as the average thickness between the maximum thickness and the minimum thickness. If the aspect ratio deviates from the above range, it may be difficult to define it as a hexagonal plate.

The hexaferrite powder 110 may have any one of crystal structure selected from M type, U type, W type, X type, Y type and Z type, and the resonance frequency (f r ) i ) is shown in Table 1 below.

ferrite
type The Ms
(emu / g) Hc
(Oe) Tc
(K) f r
(GHz) μ i BaM BaFe 12 O 19 72 3200 450 43.5 <2 SrMμ SrFe 12 O 19 74 ~ 92 3590 460 50 <2 Co 2 Y Ba 2 Co 2 Fe 12 O 22 34 55.2 340 5.7 3 Co 2 Z Ba 3 Co 2 Fe 24 O 41 50 108 410 1.3 to 3.4 19 Co 2 W BaCo 2 Fe 16 O 27 54.78 5.88 490 1-3 ~ 3.5 Co 2 X Ba 2 Co 2 Fe 28 O 46 69 - 501 1.2 ~ 2.5 Co 2 U Ba 4 Co 2 Fe 36 O 60 51 175 ~ 1598 434 30 to 40 ~ 1.3

(Where Ms is the saturation magnetization, Hc is the coercive force, and Tc is the crystallization temperature)

Generally, it is known that the hexaferrite powder maintains a predetermined permeability up to the frequency region band exceeding the frequency limit of the spinel ferrite, since it has an easy magnetization direction in a plane perpendicular to the c-axis of the crystal. Therefore, the hexaferrite powder can be used in the high frequency band.

As shown in Table 1, the Z-type hexaferrite powder has a relatively high initial permeability (mu i ) and exhibits excellent high-frequency characteristics, which is advantageous for downsizing the antenna.

M type hexaferrite powders exhibit high saturation magnetization values and high self resonance frequency (SRF) characteristics, which may be effective in reducing investment losses.

Since the Y type hexaferrite powder exhibits intermediate characteristics between the M type and the Z type, it can have a high permeability in the initial frequency range of the GHz band and a low loss characteristic due to the relatively high SRF characteristic, It is one of the most promising materials as a material.

The hexaferrite powder (110) of this embodiment can be represented by the following chemical formula (1).

&Lt; Formula 1 >

Ba 1-x Sr x Co 1-y [Me] y Fe m O n

X, y <1, 12 <m <36 and 19 <n <60), where [Me]

For example, The Y-type hexaferrite powder can be represented by the following formula (2).

(2)

Ba 1-x Sr x Co 1-y [Me] y Fe 12 O 22

Where [Me] is one selected from Zn, Mn and Cu, 0 < x, y < 1,

As the hexaferrite powder (110) having the above-mentioned formula, a single-phase sintered powder produced by calcination at a temperature of 1050 ° C to 1250 ° C may be used.

FIG. 3 is a graph showing an X-ray diffraction (XRD) analysis pattern of the hexagonal plate-shaped Ba 2 Co 2 Fe 12 O 22 sintered powder used in the present invention by calcination temperature.

Referring to FIG. 3, it can be seen that the Y-type hexaferrite sintered powder produced at the above-mentioned calcination temperature and used in the present invention is a single phase.

The ferrite sheet 100 may be formed into a sheet by applying a magnetic field while being coated with a hexaferrite powder in a slurry state mixed with a binder or the like by a doctor blade method or the like, followed by drying.

Alternatively, the ferrite sheet 100 is coated with the slurry in a plate form by a continuous casting method using shear thinning, followed by a drying process, followed by a hot roll pressing process And may be composed of a sheet.

4 is a view for explaining the magnetic directionality of the hexaferrite powder according to the embodiment of the present invention, where H ? Represents the axial magnetic anisotropy and H ? Represents the plane magnetic anisotropy.

Referring to FIGS. 1, 2 and 4, the ferrite sheet 100 of the present embodiment has hexagonal plate-shaped hexaferrite powders 110 in a plane direction (or in a horizontal direction, H φ ). Here, the planar alignment means that the planar alignment is aligned with an inclination of 45 degrees or less.

This is because hexagonal plate-like hexaferrite powders 110 are formed in the in-plane direction (H &phiv; ) by molding (applying a magnetic field when applying the ferrite composition) or hot roll pressing process during the manufacturing process of the ferrite sheet 100, As shown in Fig.

In order to maximize the molding density and permeability of the ferrite sheet 100, it is preferable that the hexaferrite powder 110 is aligned in the ferrite sheet 100 so that the plane direction alignment is 50% or more.

This is because, in the case of hexaferrite powder 110, permeability of the hexaferrite powder 110 is known to be higher than that of the hexaferrite powder 110 because it is known that the magnetic anisotropy in the plane direction is maximized and the magnetic anisotropy in the axial direction is minimized, 1 &lt; / RTI &gt;

The following equation (1) shows Snoek's Law for hexaferrite, which is the ratio of the axial magnetic anisotropy to the plane magnetic anisotropy.

Figure pat00001

(1) where μ ST is the static permeability, f max is the maximum resonance frequency, H θ is the axial magnetic anisotropy, H φ is the plane magnetic anisotropy, and (1/2) γ × 4Ms is the static magnetic permeability It means constant.

It can be seen from Equation (1) that the permeability of the ferrite sheet 100 is increased when the planar orientation degree of the hexaferrite powder 110 is 50% or more.

On the other hand, in the magnetic field, the applied magnetic field strength at the time of molding is It is preferably in the range of 1T (Tesla) to 2T. At this time, If it is less than 1 T, there may be a difference in frictional force between the powder according to the slurry viscosity and the binder, powder and powder, but it is generally difficult to achieve the desired planar alignment degree. On the other hand, if the above-mentioned factor magnetic field strength exceeds 2T, the manufacturing cost of equipment maintenance and related processes can be increased.

Also, it is preferable that the roll pressing process is performed by applying a pressure of 0.25 ton / cm to 2 ton / cm to the dried ferrite sheet. At this time, if the pressing pressure is less than 0.25 ton / cm, the film density may be lowered, whereas if it exceeds 2ton / cm, the permeability may be decreased due to the increase of the coercive force due to the crack generated in the powder.

In order to increase the permeability of the ferrite sheet 100, the hexaferrite powder 110 is preferably filled in the ferrite sheet 100 at a packing ratio of 70 to 93%. If the filling rate is less than 70%, the permeability may be lowered. On the other hand, when the filling rate exceeds 93%, the flexibility of the sheet is lowered and the formability is deteriorated.

Further, the ferrite sheet 100 has a particle size distribution of the hexaferrite powder 110 The adjustment of the permeability and the investment loss may be controlled.

The hexaferrite powder 110 of this embodiment preferably has an average particle size of 1.5 mu m or less. In this case, since the hexaferrite powder 110 has a single magnetic domain (i.e., terminal spheres) in which the magnetic domain wall is not observed, there is no migration of the magnetic domain wall during alignment, .

On the other hand, when the average particle size of the hexaferrite powder 110 is more than 1.5 탆, the powder is composed of multi-sphere having a magnetic domain wall, and is difficult to align in the plane direction due to wall wall resonance, have.

The binder 120 constituting the ferrite sheet 100 is not particularly limited as long as it can fix the hexaferrite powder 110 and may be appropriately selected according to the purpose. Examples thereof include chlorinated polyethylene (CPE) Poly vinyl butyral (PVB), acryl, and the like may be used.

The ferrite sheet of the present embodiment optimizes the plane magnetic anisotropy and the packing ratio of the hexagonal plate hexaferrite powder under the same composition and can satisfy both high permeability and low investment loss characteristics in a high frequency band of 1 GHz or more.

According to a preferred embodiment of the present invention, the ferrite sheet of the present invention has a property that the permeability (μ) is at least 1.8 or more, preferably 2.0 or more, and the investment loss (tan δ) is 0.05 or less in the frequency band of 2.1 GHz have.

As a result, the ferrite sheet of the present embodiment is suitable for mounting as a component constituting an antenna to a portable communication apparatus such as a cellular phone. In this case, it is possible to manufacture a magnetic body antenna that simultaneously satisfies both miniaturization, high efficiency, and wideband characteristics in a high frequency band of 1 GHz or more.

In addition, the ferrite sheet 100 of the present embodiment is formed by drying by heat treatment at a predetermined temperature and time without a sintering process. That is, since the ferrite sheet 100 is formed not in a sintered body but in a dry state, the ferrite sheet 100 may have a density of 4.3 or less, and unlike a conventional sintered body, a binder is contained in the final sheet product.

Normally, when a magnetic substance sheet containing a ferrite powder and a binder is subjected to a sintering process, the binder is volatilized in a sintering process and a magnetic substance sheet having a density of 5.0 or higher is produced. Such a magnetic substance sheet having a density of 5.0 or more has no flexibility and therefore can not be applied to the production of a magnetic material (for example, an antenna) of an electronic part requiring flexibility.

Conventional ferrite sintered sheets have been provided with some flexibility in the sheet by a breaking method. However, in this case, due to the debris inevitably generated at the edge portion at the time of sheet cutting in a desired shape, There is a problem that the reliability of the apparatus is deteriorated.

However, the ferrite sheet 100 of the present embodiment can be provided with flexibility because it is manufactured by a drying process only without sintering process, unlike the existing magnetic material sheet which has undergone the sintering process, and has the same low density as ordinary thermoplastic plastics. Therefore, since the ferrite sheet 100 is excellent in moldability (workability), it is applicable not only to the production of magnetic materials of electronic parts requiring flexibility but also to suppress the generation of debris at the edge portions in sheet cutting of a desired shape, It is possible to improve the reliability.

The drying process during the production of the ferrite sheet 100 of the present embodiment is preferably carried out at a temperature of 100 ° C to 150 ° C. If the drying step is carried out at a temperature lower than 100 ° C, the drying may be insufficient and the process time may be prolonged. On the other hand, when the drying step is conducted at a temperature higher than 150 ° C, the binder may be deformed,

In the meantime, the present invention has been described with reference to FIG. 1. However, the present invention is not limited to the ferrite sheet 100, and will be described later with reference to FIG.

FIG. 5 is a cross-sectional view of a ferrite sheet according to another embodiment of the present invention, showing an ideal state.

Referring to FIG. 5, a ferrite sheet 100 'according to another embodiment of the present invention may be formed into a plate-like sheet form including a hexaferrite powder 110 and a binder 120 and stacked in a plurality of layers.

The remainder of the structure of the ferrite sheet 100 'is the same as that of the ferrite sheet 100 of FIG. 1, except that the ferrite sheet 100' is composed of multiple layers. Therefore, only the differences will be described.

It is preferable that the ferrite sheet 100 'is formed of a suitable combination thereof because the film density and the permeability are controlled according to the number of layers, the thicknesses of the layers and the total thickness of the sheets.

As the thickness of the ferrite sheet 100 'is thinner, the hexaferrite powder 110 can be easily aligned, which is advantageous for increasing the permeability. Even if the number of layers is increased, the gap between adjacent layers is reduced through a process such as hot roll pressing, The density can be increased.

The ferrite sheet 100 'is preferably composed of 4 to 80 layers, a thickness of 0.03 to 0.05 mm, and a total thickness of 0.1 to 0.5 mm, but is not limited thereto.

The ferrite sheet 100 'may be formed in a plurality of layers by repeating the process of manufacturing the ferrite sheet 100 of FIG. When a hot roll pressing process is used to manufacture the ferrite sheet 100 ', the hot roll pressing process may have a different number of layers to be applied depending on the film density of the desired ferrite sheet 100'.

The ferrite sheet 100 'shown in FIG. 5 can satisfy both high permeability and low investment loss characteristics in a high frequency band of 1 GHz or more, and can be given flexibility, as in the ferrite sheet 100 of FIG.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Ferrite Sheet Manufacturing

Example 1

1 kg of Ba 2 Co 2 Fe 12 O 22 powder having an average particle size of 1.5 μm was mixed with 100 g of chlorinated polyethylene (CPE), and a magnetic field of 1T was applied while applying it to a substrate with a thickness of 0.03 mm by a doctor blade method. Thereafter, after drying for 1 hour in an oven maintained at 120 캜, eight sheets were laminated to prepare a ferrite sheet having a total thickness of 0.5 mm. The Ba 2 Co 2 Fe 12 O 22 powder in the ferrite sheet had a surface orientation degree of 60% and a filling ratio of 70%.

The Ba 2 Co 2 Fe 12 O 22 powder was prepared by a conventional solid phase synthesis method, and then 278 g of BaCo 3 , 124 g of Co (OH) 2 and 676 g of Fe 2 O 3 were mixed and then calcined at 1100 ° C. for 3 hours. The powder was obtained by 6 passes milling using an Apex milling apparatus, followed by drying and sieving.

Example 2

The remainder was carried out in the same manner as in Example 1, except that the surface orientation degree of Ba 2 Co 2 Fe 12 O 22 powder was 65% and the filling ratio was 73%.

Example 3

The remainder was performed in the same manner as in Example 1, except that the surface orientation degree of Ba 2 Co 2 Fe 12 O 22 powder was 70% and the filling ratio was 76%.

Example 4

The remainder was carried out in the same manner as in Example 1, except that the surface orientation degree of Ba 2 Co 2 Fe 12 O 22 powder was 75% and the filling ratio was 79%.

Example 5

The remainder was performed in the same manner as in Example 1, except that the surface orientation degree of the Ba 2 Co 2 Fe 12 O 22 powder was 80% and the filling ratio was 82%.

Comparative Example

Except that the magnetic field was not applied and the filling ratio of the Ba 2 Co 2 Fe 12 O 22 powder was 70% when the mixture of the mixture of Ba 2 Co 2 Fe 12 O 22 powder and CPE was applied. .

6 is a scanning electron microscope (SEM) photograph showing the microstructure before and after the aligning step of the ferrite sheet according to the first embodiment of the present invention. The microstructure before the aligning step is shown in (a) The tissue is shown in (b).

6 (a), hexagonal Ba 2 Co 2 Fe 12 O 22 powders are randomly distributed. On the other hand, after the aligning process, as shown in FIG. 6 (b) It was confirmed that hexagonal Ba 2 Co 2 Fe 12 O 22 powder was aligned in the plane direction as shown in FIG.

FIG. 7 is a TEM micrograph of a Ba 2 Co 2 Fe 12 O 22 powder used in an embodiment of the present invention, wherein the particle size is 1 μm.

Referring to FIG. 7, it can be seen that the Ba 2 Co 2 Fe 12 O 22 powder for ferrite sheet of the present embodiment is a terminal powder having a single magnetic domain free of a magnetic domain wall.

2. Property evaluation

The permeability ([mu]) and the investment loss (tan [delta]) measured according to the frequencies of the ferrite sheets according to Examples 1 to 5 and Comparative Examples are shown in Table 2 and FIG.


division
use
powder powder
Granularity
(탆) Face direction
Alignment chart
(%) powder
Filling rate
(%) use
frequency
(GHz)
Investment ratio
Investment loss Example 1

Ba 2 Co 2 Fe 12 O 22

1.5 60 70

2.1 1.8 0.04 Example 2 65 73 1.86 0.05 Example 3 70 76 1.92 0.05 Example 4 75 79 2.0 0.05 Example 5 80 82 2.1 0.05 Comparative Example 0 70 1.67 0.04

Referring to Table 2 and FIG. 8, the ferrite sheets of Examples 1 to 5 exhibited a permeability (μ) of 1.8 or more and an investment loss (tan δ) of 0.05 or less in the frequency band of 2.1 GHz.

In particular, Examples 4 to 5, in which the surface direction alignment and filling rate are relatively high, exhibit excellent performance with a high permeability (μ) of 2.0 or more and a low investment loss (tan δ) of less than 0.05 in the 2.1 GHz frequency band. That is, the permeability increases as the surface direction alignment and filling rate are higher under the same composition.

On the other hand, in the comparative example having no plane direction alignment, it can be confirmed that the magnetic permeability (μ) in the frequency band of 2.1 GHz is as low as 1.67.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, and that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention. However, it should be understood that such substitutions, changes, and the like fall within the scope of the following claims.

100, 100 '; A ferrite sheet 110; Hexaferrite powder
120; Binder H ?; Axis magnetic anisotropy
H φ ; Plane magnetic anisotropy

Claims (11)

A ferrite sheet comprising a binder and hexaferrite powder in the hexagonal plate shape arranged in a plane direction.
The method according to claim 1,
The ratio of the thickness of the hexaferrite powder to the particle size is from 30: 1 to 4: 1 Ferrite sheet.
(The particle size of the powder is defined as the maximum diagonal length, and the thickness is defined as the average thickness between the maximum thickness and the minimum thickness.)
The method according to claim 1,
Wherein the hexaferrite powder has a planar orientation degree of 50% or more.
The method according to claim 1,
Wherein the filling ratio of the hexaferrite powder in the ferrite sheet is 70 to 93%.
The method according to claim 1,
The hexaferrite powder has a crystal structure of any one of Y type, Z type, M type, W type, X type and U type.
6. The method of claim 5,
The hexaferrite powder is represented by the following formula (1).
&Lt; Formula 1 >
Ba 1-x Sr x Co 1-y [Me] y Fe m O n
X, y <1, 12 <m <36 and 19 <n <60), where [Me]
6. The method of claim 5,
The Y-type hexaferrite powder is represented by the following formula (2).
(2)
Ba 1-x Sr x Co 1-y [Me] y Fe 12 O 22
Where [Me] is one selected from Zn, Mn and Cu, 0 < x, y &lt; 1,
The method according to claim 1,
Wherein the average particle size of the hexaferrite powder is 1.5 占 퐉 or less.
The method according to claim 1,
Wherein the ferrite sheet has a permeability (mu) of 1.8 or more and an investment loss (tan delta) of 0.05 or less in a frequency band of 2.1 GHz.
The method according to claim 1,
Wherein the ferrite sheet has a density of 4.3 or less.
The magnetic substance antenna according to any one of claims 1 to 10, wherein the magnetic permeability (μ) is 1.8 or more and the investment loss (tan δ) is 0.05 or less in the frequency band of 2.1 GHz.
KR1020140054781A 2014-05-08 2014-05-08 Ferrite sheet and magneto dielectric antenna using the same KR20150128048A (en)

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