JPS6289746A - Material for suppressing unnecessary mode - Google Patents

Abstract

PURPOSE:To obtain a material for suppressing the unnecessary mode, effective to suppress the unnecessary mode of high-frequency radiation especially of >=10GHz and placed in a case of various electronic apparatus such as a converter of a satellite broadcast receiver, by using a specific ferrite as a component. CONSTITUTION:One or more kinds of powdery ferrite (W-type, Y-type or Z-type) having a composition represented by the formula I (x+y+z=1 0.05<=x<=0.3; 0.1<=y<=0.4; 0.55<=z<=0.8; Me is a combination of one or more metal atoms) is blended in a polymer matrix (e.g. rubber) at a ratio of 30-70vol% and the obtained composition is formed to obtain the objective material.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background Technical Field of the Invention The present invention relates to a material that suppresses unnecessary modes occurring in electronic devices, particularly in metal cases.

Prior art and its problems recently? ``The frequency of child devices, especially electronic devices for communication and broadcasting, is increasing, and as a result, many devices are being used at frequencies above UHFHF.

For this reason, problems such as interference due to radiated noise between elements and noise due to harmonics within the metal case of electronic equipment have become serious.

In order to suppress such unnecessary modes, an unnecessary mode suppressing material made of a composite of ferrite powder and resin or rubber is attached to the most effective part within the metal case of an electronic device. In this case, conventional ferrite powders include Mn-Zn ferrite, which is spinel ferrite, and Ni-Zn ferrite.
N-ferrite powder is used.

To suppress unnecessary modes, a method is used to absorb unnecessary radiation by utilizing the magnetic loss of the material. Magnetic loss is caused by the presence of μ, ″ in the complex relative permeability μ, = μ, ′−jμ,″, and the natural resonance frequency of the magnetic moment (f,
) has a maximum value near μ,″. Therefore, it is desirable that the frequency be near the natural resonance frequency or within the frequency range used.

However, spinel ferrite has f of 4 GHz or less, and can only be used as an unnecessary moat suppressing material at frequencies of 10 GHz or less.

Therefore, it is desired to develop unnecessary mode suppressing materials that absorb unnecessary radiation at higher frequencies.

+1 Purpose of the Invention The purpose of the present invention is to suppress unnecessary motes that are effective in suppressing unnecessary modes at high frequencies, particularly at 10 GHz or higher, and by changing the composition, it is possible to suppress unnecessary modes at any frequency. The purpose is to provide materials.

■Disclosure of invention Such objects are achieved by the invention described below.

That is, the present invention includes at least one kind selected from ferrites having a composition represented by the following formula (A), and has an electric f
1111 is an unnecessary mode suppressing material disposed in at least a portion of a case of a device.

Formula (A) (Bad)x (Men)y (Fe203)z
(In the above formula (A), x+y+z= 1.0.05
≦x≦0.3.0.1≦y≦0.4.0.55≦Z≦0
．． 8, and Me represents one kind or a combination of two or more kinds of metal atoms. ) ■Specific structure of the invention The specific structure of the present invention will be explained in detail below.

The unnecessary mode suppressing material of the present invention contains at least one kind of powder selected from ferrite having a composition represented by the following formula (A).

Formula (A) (Bad), (Men), (Fe2o3)2 Above formula (A
), x+y+z=1.0.05≦x≦0.3.
0.1≦y≦0.4, 0.55≦z≦0.8.

Me represents one kind or a combination of two or more kinds of metal atoms, and more specifically, MeO represents (Coo)w (
Me'o)2-W. However, 0≦W≦z, Me' is a divalent metal ion, F
e”, Mn”, N t 2+, M g l+ and Cu
Represents one type or a combination of two or more types selected from metal atoms that can be 2+.

The reason why such a composition range is used is that a sufficient unnecessary mode suppression effect cannot be obtained in a high frequency region outside this range.

FIG. 1 shows a ternary diagram of the composition range of the ferrite of the present invention.

Among these, those having compositions represented by the following formulas (I) to (V) are preferred.

Formula (1) % Formula % Formula (II) Coy, Me' y2Ba2Fe12022 Formula (m) Me '2 Ba2 Fe12O22 Formula (IV) Coz, Me' z2Ba3Fe2404° Formula (V) CO2Ba3 Fez404+ In the above formula CI>, XI +X2 =2 .0.6≦
×1≦1.7, and Me′ has the same meaning as above.

These embodiments include Cox, Znx3Me"X4BaFe, 602° (where x + + X3 + X4 = 2.0.6≦
×1≦1.7, x3≦1.4, and ×4≦1.3. )
; Cox, Znx3BaFe+sO□y (where X, +
x3 =2, 0.6≦x1 =1, 7, x3≦1.
It is 4. ); COXIM e″X4B a F e 16027 (
Here, X, +x4 =2, 0.6≦xl =1
, 7, ×4≦1.3. );

Here, M e ” is a divalent metal ion, Fe2+, p
J (12+, Ni 2+ , Mg 2+ and Cu 2+
One or two selected from neighboring metal atoms
Represents a combination of more than one species.

In the above formula (II), yl+y2=2, y≦1.
6, and Me'' has the same meaning as in formula (I) above.

These embodiments include Coy, Zny3Me" y4 Ba2 Fe,
2022 (here, y1+y2+y4=2, y1≦1.
6, y2≦z, y3×2. )；Coyl Zny
3Ba2 Fe+zO2□ (here, yl +y3 =
2, y1≦1.6, y3×2. ); Coy, Me” y4B, a2Fe+202z (here, y++y4=2, y, ≦1.6, y4×2.)
: Included.

In addition, "Me" has the same meaning as above.

In the above formula (IV), z, +z2=2.0.8≦z
1 x 2, and Me'' has the same meaning as in the above formula (I).

These embodiments include: Coz, Znz3 Me” Z 4 B a 3
F e 24041 (where z, +z3+z4=2
．． 0.8≦z, ≦z, Z3≦1.2, and z4≦1.0. ): Coz, Znz3Ba3 Fe240. .

(Here, z, +z3 = 2.0.8≦z, <2, z
3≦1. 2); Coz, Me” z4Ba,, Fe240., (where Zn + z4=2.0.8≦z1<2, Z4≦1.0
It is. ); is bitter.

In addition, "Me" has the same meaning as above.

Hereinafter, the ferrite having the composition represented by formula (I) will be referred to as W.
Called the type, B a Fe + aO2? is abbreviated as W.
Moreover, those represented by formulas (II) and (III) are Y
Ba2Fe, 2022 is abbreviated as Y. And those represented by formulas (TV) and (V) are called Z type,
Ba:+Fe2a04+ is abbreviated as Z.

Such formula (I) which is preferred in the present invention -
The reason why the composition of the W-type, Y-type, and Z-type ferrite represented by (V) is set to the range described above is that the unnecessary mode suppression effect is particularly good in the high frequency region.

In the preferred composition range of the present invention, the unnecessary mode suppression effect is 10 dB or more at frequencies of 8 GHz or more.

This preferred composition range is shown in Figures 2, 3, and 4 for W type, Y type, and Z type, respectively.
It is shown as a ternary diagram regarding n2+, Me"".

In this case, the state in which the oscillator and spectrum analyzer are directly connected is OdB, the oscillator sends a signal, and the spectrum analyzer reads the voltage of the signal that passes through the copper case installed between the oscillator and spectrum analyzer. It is measured by The number of samples (unwanted mode suppression material) attached to a part of the case is 74.
Use one with dimensions of x31x2mm.

Particularly preferred examples of ferrites having such compositions are shown below.

W-type C015Zno5W Y-type Coo, Zn, , Y oZnY CoIs Zno, , Y Coo5Zn+, o Mgo, s Y Z-type o2Z Such ferrite powder has a hexagonal crystal structure.
The average particle size is usually about 1 to 50 μm. It is contained in the form of these crystal grains or crushed pieces.

In the present invention, it is preferable to use one or more of the above W type, Y type, and Z type ferrites, but
α-Fe203. BaFe+12+19 (abbreviated), B
It may contain aFe2O, (abbreviated as F), CoFe2O4 (abbreviated as S), etc., and by including these materials, the composition range of the present invention may be satisfied as a whole. α-Fe20. , BaFe2O4 is a non-magnetic material, and BaFe+20+9, CoFe2
O4 etc. also deteriorate the characteristics, so it is desirable to have a small content of them, but specifically, even if they contain about 0.2 mol per 1 mol of W-type, Y-type, and Z-type ferrite, the characteristics will not be improved. It won't definitely make things worse.

Further, in the present invention, it is desirable that Me be mainly composed of Co. Specifically, in formula (A), 0.1≦
W≦z. 0, particularly preferably in the range of 0.5≦W≦1.7.

Preferably, the unwanted mode suppressing material of the present invention includes a polymer matrix.

Rubber or resin is used as the polymer matrix. There are no particular limitations on these materials, and one or a combination of two or more of various resins such as epoxy resins and silicone resins, and various rubbers may be used.

In the present invention, the ferrite powder is mixed with the polymer matrix at a ratio of 30 to 70% by volume, preferably 40 to 60% by volume.

The reason why such a proportion is used is that the present invention is not effective when the proportion is less than 30 volume %, and when it exceeds 70 volume %, moldability, strength, etc. are reduced.

Note that the polymer matrix may further contain powders, flakes, fibers, etc. of other conductive materials or magnetic materials.

A method for manufacturing the unnecessary mode suppressing material of the present invention will be described.

First, ferrite powder is usually obtained by mixing, firing, and pulverizing predetermined raw materials.

In this case, the firing temperature is 100~b, kept at 1400℃ for a predetermined time, and heated at 100~500''C/hr.
Cool at a rate of Furthermore, air, nitrogen, or the like is used as the firing atmosphere.

In this case, as mentioned above, it is preferable to generate W-type, Y-type, and Z-type ferrite in a single phase or a composition in which two or three types of W, Y, and Z phases are mixed together. a-Fe203. within the composition range of the present invention.
BaFe204. BaFe120+q, CoFeO4
Usually, the total of W phase, Y phase and Z phase is 1.
It may be contained in an amount of 0.2 mole or less per mole.

Moreover, two or more types of particles having different compositions among these may be used. In this case as well, the amount of other phases is preferably 0.2 mol or less per 1 mol of the W phase, Y phase, and Z phase in total.

After that, ferrite powder is added to the polymer matrix for 30~
After kneading and molding at a ratio of 70% by volume, preferably 40 to 60% by volume, it is processed.

Such an unnecessary mode suppressing material of the present invention is disposed in at least a part of the case of various electronic equipment, such as a converter or a tuner of a satellite broadcast receiving device.

That is, it may be composited with a polymer matrix to form a sheet and placed at a predetermined position inside a case made of metal or the like, or it may be applied as a paint to a predetermined position or the entire area inside the case.

Furthermore, depending on the case, the case itself may be configured.

The thickness of the unnecessary mode suppressing material of the present invention is usually 1 to 1.
It is said to be about 5mm.

■Specific effects of the invention According to the present invention, since it contains at least one kind selected from ferrite having the composition represented by the above formula (A), it is effective in suppressing high frequencies, particularly unnecessary modes of 10 GHz or higher. A material for suppressing unnecessary modes can be obtained. Further, by changing the composition of the ferrite, it is possible to suppress unnecessary modes at any frequency.

(2) Specific Examples of the Invention The present invention will be explained in more detail by showing specific examples of the present invention.

Example unnecessary mode suppressing material (Samples 1 to 5 and samples a y f
) is described below.

(+3 Sample containing spinel ferrite (Nt-Zn&) (comparison) Sample Ferrite composition 1 (N j 0) 31 (Z n 0) 20 (F
6203) 49 Predetermined raw materials are Jj I! so that ferrite having the above composition is obtained. The mixture was wet mixed in a ball mill, dried, and fired. The firing temperature is 3
The temperature was raised at a rate of 00°C/hr, maintained at 1000°C for 2 hours, and then cooled at a rate of 300°C/hr. The firing atmosphere was air.

This was wet-pulverized in a ball mill to an average particle size of 2μI,
Dry.

This powder is kneaded with chloroprene rubber using a rubber roll,
After hot pressing and vulcanization, it was processed by cutting, polishing, etc. The ferrite powder was mixed with the rubber at a ratio of 55% by volume.

(2) Sample containing W-type ferrite (average particle size 9 μl) (
(present invention) ■ Sample Ferrite composition 2 (B a 0) (Co O), 5 (Z n
O) o,5(Fe203)a (Co,..., Zno 5W) Produced in the same manner as in the case of (1). However, during firing, the temperature was maintained at 1350°C for 6 hours.

(3) Sample containing Y-type ferrite (average grain size 4μI) (
Invention) II Sample Ferrite composition 3 (Bad), (Coo). 5(ZnO)+
, 5 (Fe 203 ) c (COo, s Znt, s Y) 4 (Bad) 2 (Coo), o (znoL
.

(Fe203)6(CoZnY) It was produced in the same manner as in the case of (1). However, during firing, the temperature was maintained at 1200°C for 12 hours.

(4) Sample containing Z-type ferrite (average grain size 4 μm) (
Invention) ■ Sample Ferrite composition 5 (BaO)a (Coo)2 (Fez 03)
+2(Co2Z) It was produced in the same manner as in the case of (3).

(5) Sample (present invention) ■ Sample Ferrite composition a (BaO)14(Con)t(ZnO)y
(Fe20*)t2b (BaO)+5(C
OO)t(ZnO)y (Fez03)etc
(BaO)+1(CoO)*, 5(ZnO)s, 1(F
eaOs)atd (BaO)16(CO
O)a(ZnO)a (Fe2e3)aa(1) was produced in the same manner as in the case of (1). However, the temperature during firing should be 12
The temperature was kept at 00°C for 12 hours, and the firing atmosphere was air.

These samples a to d- had an average particle size of 5-.

When these samples a Nd were subjected to X-ray diffraction, it was found that the following crystal phases were generated.

Sample Crystal phase a. W phase, Y phase, and Z phase are mixed.

b Almost Y single phase (some M phase is included).

c　　　　　Y phase and W phase mixed (Some S phase is included).

d　　　　Y phase and W phase are mixed.

(6) Sample containing spinel ferrite (Co-Zn system) (comparison) Sample Ferrite composition e(Cod)so (Fe203)r.

f (tl:oO) 30 (ZnO)
20 (pe2o3) li.

It was produced in the same manner as in case (1). However, during firing, the temperature was maintained at 1250° C. for 2 hours, and the firing atmosphere was air. These samples e and f had an average particle size of 5-.

Samples 1 to 5 prepared as described above were fixed to the specified dimensions (74x
31 x 2 mm) and a copper case (size 74 x 74 x
31mm).

This case is installed between the oscillator and the spectrum analyzer, the oscillator sends a signal, and the spectrum analyzer converts the voltage of No. 19 passing through the copper case to 8 GHz.
Measurements were made at the above frequencies.

In addition, measurements were made in the same way when no sample was attached to the copper case (no attachment).

In the above case, the transmission level in a state where one oscillator and the spectrum analyzer are directly connected is OdB.

The results for samples 1 to 5 are shown in FIGS. 5, 6, 7, and 8.

In addition, the natural resonance frequency f and μ at 12.25 GHz were determined for Samples 1 to 5 and Sample a x f. The results are shown in the table.

Sample ferrite
f, [G11zl 12.25GHz
μ,′] Ni-Zr+7z light
3
0.242 Go, 5Zn, 5W
15
1.13 Coo, sZn+, s Y
7
0.704 GoZnY
9 0.785 Go2Z
5 0.62a
(BaO)+4(C00)y(ZnO)7(Fe2
03)72 5 0.54b (Bad)
+9(Coo)t(ZnO)y(Fe20+)at
7 0. ti8C(BaO)+4(000)9
．． 5(ZnO)9.5(Fe2o3)a76 0.
67d (mouth aO)+e(COO)a(ZnO)a(
Fe20+)sa 5 0.
64e (COO)5o(FezO3)go
>15 0.10f (CoO)3o
(ZnO)2o(Fe203)r,o”t
O, 39 From FIGS. 2 to 8, it can be seen that the sample of the present invention has a high f and suppresses unnecessary modes at high frequencies. It can also be seen that the frequency range in which unwanted modes are suppressed changes depending on the composition of the ferrite.

In addition, as shown in the table, samples 2 to 5 of the present invention and a
~d is higher than f, μ at 12.25 GHz,''
Since this is also large, it is thought that unnecessary modes can be suppressed at high frequencies.

On the other hand, since the conventional material Sample 1 has a low fr, its characteristics at high frequencies deteriorate.

Further, although samples e and f, which are outside the composition range of the present invention, have high f, μm'' at 12.25 GHz is too low, so it is considered that unnecessary modes cannot be sufficiently suppressed at high frequencies.

The effects of the present invention are clear from the following.

[Brief explanation of drawings]

Figure 1 shows 3 composition ranges of the ferrite of the present invention.
This is the original drawing. Figures 2, 3 and 4 are respectively C0XI Z
nx3Me” X4 W (Xl +X3 +x4=2
), Coy, Zny3Me"y4Y(:/+ 1y3
+y4=2), and Coz. Znz 3 Me” z 4 Z (z, +Z
3 +Z 4 =2), and the part surrounded by the thick line shows the composition range in which the unwanted mode suppression effect is 10 dB or more at frequencies of 8 GHz or more. Figures 5, 6, 7 and 8 are CO
I52 no, 5 W%C00, 5Z n +, aY,
Graph (□) showing the unwanted mode suppressing effect of the unwanted mode suppressing material of the present invention containing CoZnY and Co2Z as a relationship between transmission level (dB) and frequency (GHz)
It is. In each case, for comparison, graphs for the case without (----) and the case containing Ni--Zn ferrite (-1--) are also shown at the same time. Applicant TDC Co., Ltd. FIG, I ears Ba0 FIG, 2C. Me'2+(×・) FIG, 3 FIG, 4 C. "J2' (Z4) Appropriate level (dB) Transmission level (dB) Embankment level (dB)

Claims (3)

[Claims] (1) An unnecessary mode suppressing material comprising at least one selected from ferrites having a composition represented by the following formula (A) and disposed in at least a part of the case of an electronic device. Formula (A) (BaO)_x(MeO)_y(Fe_2O_3)_z
(In the above formula (A), x+y+z=1, 0.05≦
x≦0.3, 0.1≦y≦0.4, 0.55≦z≦0.
8, and Me represents one kind or a combination of two or more kinds of metal atoms. ) (2) Claim 1, which includes the ferrite powder and a polymer matrix, and is located in a part of the case.
Unwanted mode suppressing material described in section. (3) The unnecessary mode suppressing material according to claim 2, wherein the polymer matrix is rubber or resin.