JP2002260911A - Sintered magnetic oxide and high-frequency circuit part using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintered magnetic oxide which has excellent magnetic properties and is usable up to a high-frequency band of a few hundred MHz to GHz, contains no dissimilar phase other than Y-type hexagonal ferrite as much as possible, and can be baked at 1000 deg.C or below, especially around 900 deg.C, and to provide a high-frequency circuit part using the same. SOLUTION: This magnetic oxide sintered body contains Y-type hexagonal ferrite of 80% or above. The magnetic oxide sintered body contains 3 to 15 mol% cobalt oxide in terms of CoO, 5.5 to 17 mol% copper oxide in terms of CuO, 57 to 61 mol% iron oxide in terms of Fe2 O3 , and residual mol% AO (AO is either BaO or SrO) and 0.5 to 7 wt.% bismuth oxide(Bi2 O3 ) as an auxiliary component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic oxide sintered body used for high-frequency circuit components and a high-frequency circuit component using the same.

[0002]

2. Description of the Related Art In recent years, demands for electronic components having high inductance and impedance in a high frequency band have been increasing along with miniaturization and higher frequency of electronic devices. In order to obtain a small size and high inductance and impedance, it is desirable to produce a coil having a laminated structure in which a conductor is built in a magnetic material by a so-called printing method or sheet method. The number of turns of the coil can be increased by adopting the laminated structure, and since the structure also becomes a closed magnetic circuit, high inductance,
The impedance is obtained.

[0003] As a conductor material incorporated in the sintered body,
In general, silver (Ag) is widely used in consideration of electrical resistivity, melting point, cost, and the like. The melting point of silver is 1000 ° C
Because of the following, as a magnetic material for a laminated structure, generally, NiZn-based ferrite, which can obtain a high sintered density even at 900 ° C., has been used.

[0004] However, NiZn-based ferrite has a low magnetic anisotropy, causing natural resonance at a frequency of several hundred MHz, and cannot be used in a frequency band of GHz.

[0005] An air-core coil using a non-magnetic material may be used as a high-frequency specification. However, if a non-magnetic material is used, it is difficult to obtain high inductance and impedance.

On the other hand, the hexagonal ferrite has a different magnetic anisotropy between the in-plane direction of the hexagonal plate-like crystal and the direction perpendicular to this plane, so that natural resonance hardly occurs, and
It has the feature of having high magnetic permeability up to the frequency band of z. However, in this case, it is necessary to raise the firing temperature in order to obtain desired sintering density and magnetic properties.

Attempts have been made in the past to use hexagonal ferrite, which has a high formation temperature, to burn it at a temperature lower than the melting point of Ag by using a low-melting oxide. However, the rate of formation of a soft magnetic phase is low, and the magnetic properties of hexagonal ferrite are low. It was difficult to exhibit the characteristics sufficiently.

One of similar prior arts related to the present application is Japanese Patent Application Laid-Open No. Hei 9-167703. In this publication, Z
Type hexagonal ferrite (Ba, Sr, Pb) ₃ (Co _1-x C
U _x ) ₂ Fe ₂₄ O ₄₂ has been mainly studied, and V ₂ O ₅ , CuO, Bi ₂ O ₃ , MoO ₃ , W
O ₃ and PbO are added.

In this publication, the main phase is M
Low-temperature sintering of type, Y, W, X and U hexagonal ferrites has also been reported. In particular, for those in which the main phase disclosed in the specific examples is Y-type, that is, (Ba) ₂ (Co _1-x C _x ) ₂ Fe ₁₂ O ₂₂ ,
Although the occupancy of the Y-type hexagonal ferrite is not described and unknown, the occupancy is extremely low at 700 ° C., so the occupancy is at most about 50%. It can be said that it does not exceed 80% as in the present application. As a result, the magnetic properties obtained are never satisfactory. That is, the addition of the composition and the substance in the publication enables low-temperature sintering, but the calcination temperature has not been sufficiently studied, and the rate of formation of the soft magnetic phase after sintering is low. Cannot fully exhibit the magnetic properties of Therefore, it can be said that there is a problem that it is difficult to obtain high inductance and impedance.

Further, the content of CuO in this publication is smaller than that of the present invention, and even if the effects of additives are taken into consideration, the yield of Y-type hexagonal ferrite is increased by firing at about 900 ° C. to obtain high characteristics. There was a problem that it was not possible.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to solve the above-mentioned problems and to provide magnetic characteristics up to a high frequency band of several hundred MHz to GHz. Provided is a magnetic oxide sintered body which is favorable and can be used, contains as little foreign phase as possible other than Y-type hexagonal ferrite as much as possible, and can be fired at 1000 ° C. or less, particularly around 900 ° C., and a high-frequency circuit component using the same. It is in.

[0012]

In order to solve such problems, the present invention relates to a magnetic oxide sintered body occupied by 80% or more of Y-type hexagonal ferrite. The sintered body contains 3 to 15 mol% of cobalt oxide as a main component in terms of CoO, and 5.5 to 17 mol of copper oxide in terms of CuO.
Mol%, iron oxide is 57 to 61 mol% in terms of Fe ₂ O ₃ , and the remainder is AO (AO is at least 1% of BaO or SrO).
Bismuth oxide (Bi)
₂ O ₃ ) in an amount of 0.5 to 7 wt%.

The present invention also relates to a high-frequency circuit component having a structure in which a conductor is embedded in a magnetic oxide sintered body, wherein the magnetic oxide sintered body is a Y-type hexagonal ferrite of 80%. The magnetic oxide sintered body is occupied as described above, and the main component of the magnetic oxide sintered body is 3 to 15 mol% of cobalt oxide in terms of CoO, 5.5 to 17 mol% of copper oxide in terms of CuO, and Fe ₂ O as iron oxide. 57-61 mol% in ₃ conversion, the remainder is AO (AO
Includes to at least one) of BaO or SrO, 0.5 to the bismuth oxide (Bi ₂ O ₃₎ as a sub-component
It is configured to contain 7 wt%.

In a preferred embodiment of the present invention, the calcination temperature in the production of the magnetic oxide sintered body is 850 ° C.
と し て 1000 ° C.

In a preferred embodiment of the high-frequency circuit component according to the present invention, the conductor is constituted so that silver (Ag) is a main component.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, will be described in detail magnetic oxide sintered body of the present invention.

Since the magnetic oxide sintered body of the present invention is a ceramic sintered body, it can be manufactured by an ordinary ceramic manufacturing process.

In the magnetic oxide sintered body of the present invention, as a main component, cobalt oxide is 3 to 15 mol% (preferably 5 to 10 mol%) in terms of CoO, and copper oxide is 5.5 in terms of CuO.
To 17 mol% (preferably 10 to 15 mol%), 57-61 mol% of iron oxide calculated as Fe ₂ O ₃ (preferably, 5
9 to 60 mol%), and the balance is AO (AO is at least one of BaO and SrO). AO forms, alone form of BaO or SrO, or BaO,
And SrO.

The magnetic oxide sintered body of the present invention contains bismuth oxide Bi ₂ O ₃ as an auxiliary component in an amount of 0.5 to 7 wt% (preferably 0.6 to 5 wt%).

Such bismuth oxide Bi ₂ O ₃ is mixed in the form of the oxide at the time of addition, and generally remains in the form of the oxide even after sintering, as can be seen from the examples described later. When the content of the main component is less than 3 mol%, there is a tendency that, for example, the permeability at 2 GHz decreases (for example, less than 2.0), and when the content of CoO exceeds 15 mol%, for example, 500M
There is a tendency that the inconvenience that the magnetic permeability at Hz decreases (for example, less than 2.0).

If CuO is less than 5.5 mol%, the calcination temperature tends to exceed 1000 ° C., and if CuO exceeds 17 mol%, the magnetic permeability decreases (for example, 2. (Less than 0) tends to occur.

If the content of Fe ₂ O ₃ is less than 57 mol%, or if the content of Fe ₂ O ₃ is more than 61 mol%, the magnetic permeability tends to be reduced.

In the content ratio of the subcomponent, the above B
When the content of i ₂ O ₃ is less than 0.5 wt%, 1000
There is a tendency that the sintering at a temperature of not higher than 90 ° C. makes it impossible to obtain 90% or more of the theoretical density. When the content of Bi ₂ O ₃ exceeds 7% by weight, there is a tendency that the magnetic permeability decreases. .

The addition of the Bi ₂ O ₃ subcomponent in combination with the above-mentioned CuO content makes it possible to remarkably realize low-temperature sintering. There is also a synergistic effect of improving magnetic properties. When the firing temperature is lowered, Ag is inexpensive and has low electric resistance.
Simultaneous firing with a built-in low melting point electrode material such as
An element having an electrode-integrated closed magnetic circuit configuration can be easily manufactured. The element manufactured in this manner is used, for example, as a small-sized inductor having a high Q value or a small-sized high-frequency element (high-frequency circuit component) such as a noise filter having a large impedance in a high-frequency band, particularly at a specific frequency. You.

Further, in the magnetic oxide sintered body of the present invention, 80% or more, particularly preferably 90% or more, of the magnetic oxide sintered body is Y.
It is made of type hexagonal ferrite. Here, “%” is calculated from the main peak ratio of the X-ray diffraction intensity.

Y-type hexagonal ferrite occupies 80%
If it is less than the above value, a disadvantage arises in that a high magnetic permeability cannot be obtained at a high frequency. This makes it difficult to obtain a high-frequency circuit component having high inductance and impedance.

When co-firing with a low-melting-point electrode material such as silver (Ag), the firing temperature becomes low, so that Y
In order to make the type hexagonal ferrite 80% or more, it is necessary to generate the Y type hexagonal ferrite 80% or more at the time of calcination. Depending on the composition, B
The decomposition of aFe ₁₂ O ₁₉ and BaFe ₂ O ₄ starts, and the formation of Y-type hexagonal ferrite starts.

However, BaFe ₁₂ O ₁₉ and Ba
If the decomposition of Fe ₂ O ₄ does not proceed sufficiently, the formation of Y-type hexagonal ferrite does not proceed. Therefore, in order to make the Y-type hexagonal ferrite 80% or more, the calcination temperature is 850 ° C. or more,
In particular, it is necessary to be 850-1000 ° C. further,
It is necessary to contain 5.5 to 17 mol% of CuO. If the calcination temperature is lower than 850 ° C. or the amount of CuO is out of the above range, it becomes difficult to generate Y-type hexagonal ferrite exceeding 80%. When the calcining temperature is 100
If the temperature exceeds 0 ° C. and becomes too high, fine pulverized powder cannot be obtained. Production of fine ground powder is a very important technique for low-temperature firing.

From such a viewpoint, in order to increase the yield of Y-type hexagonal ferrite at a calcination temperature of 850 to 1000 ° C. as described above, the above-mentioned C as a main component is required.
It is necessary to make the uO content 5.5 to 17 mol%.

The magnetic oxide sintered body according to the present invention is used as a high-frequency circuit component having a structure in which a conductor is embedded in a magnetic oxide sintered body, for example, an impedance or an inductor.

[0031]

The present invention will be described below in further detail with reference to specific examples.

[0032] Experimental Example I] (Example Preparation of samples and comparative sample) composition after sintering and each raw material was weighed so that the compositions shown in Table 1, 15 hour wet a steel ball mill Mixed.
Next, this mixed powder was dried in air at a temperature shown in Table 1 for 2 hours.
Time baked. Next, as shown in Table 1, a predetermined amount of Bi ₂ O ₃ was added as an auxiliary component, and the mixture was pulverized with a steel ball mill for 15 hours.

The hexagonal ferrite powder thus obtained was granulated and formed into a desired shape at a pressure of 100 MPa.

This compact was sintered in the atmosphere at the firing temperature shown in Table 1 for 2 hours. The composition of the hexagonal ferrite sintered body is as shown in Table 1 below. For each of these samples, the density and the frequency of 500 MH at 25 ° C.
The magnetic permeability at z and 2 GHz were measured and shown in Table 1. The magnetic permeability aims at a value of 2.0 or more at the frequencies of 500 MHz and 2 GHz.

The occupancy by the Y-type hexagonal ferrite was calculated from the intensity ratio of X-ray diffraction peaks using the pulverized powder of the sintered body.

[0036]

[Table 1]

[Experimental Example II] Next, an impedance element was manufactured using the magnetic material of the present invention. That is, each raw material was weighed such that the composition after sintering had a composition as shown in the sample of Example 7 in Table 1 above, and was weighed for 15 minutes using a steel ball mill.
Wet mixed for hours. Next, this mixed powder was placed in the atmosphere at 950.
Calcination was performed at 2 ° C. for 2 hours. Next, Bi ₂ O ₃
Was added and then pulverized with a steel ball mill for 15 hours.

An organic binder was mixed with the calcined powder, and a uniform green sheet was formed by a doctor blade method.

For comparison, NiCuZn-based spinel ferrite powder (NiO = 45 mol%, CuO = 5 mol%,
ZnO = 1.5 mol%, Fe ₂ O ₃ = 48 mol%, CoO
= 0.5 mol%) was also prepared.

On the other hand, a conductive paste prepared by mixing silver was prepared, and a coil was laminated on the above-mentioned green sheet in a spiral shape. Pressure was applied in the thickness direction to perform compression bonding to produce a green sheet laminate in which electrodes were sandwiched between magnetic materials. This was fired at 930 ° C. for 2 hours. A silver paste was applied to the position of the internal conductor on the side surface of the obtained sintered body, and an external electrode was baked to obtain an impedance element (high-frequency circuit component) schematically shown in FIG.
FIG. 1 is drawn as a model diagram to facilitate understanding of the internal structure of the device. In FIG. 1, reference numeral 11 denotes an inner conductor (Ag coil), reference numeral 10 denotes a terminal conductor, and reference numeral 20 denotes a ferrite.

When the impedance and the magnetic permeability of the impedance element thus obtained were measured at a frequency of 2 GHz, the impedance of the conventional NiCuZn-based spinel ferrite was 135Ω (the magnetic permeability was 1.2). According to the present invention, the impedance was 208 Ω (permeability was 3.7), which was improved by about 54% or more.

[0042]

The effects of the present invention are clear from the above results. That is, the present invention relates to a Y-type hexagonal ferrite,
A magnetic oxide sintered body occupied by 0% or more, wherein the magnetic oxide sintered body contains cobalt oxide as a main component in Co.
3 to 15 mol% in terms of O, and copper oxide in terms of CuO of 5.5
１７17 mol%, iron oxide is 57-61 mol% in terms of Fe ₂ O ₃ , the balance is AO (AO is at least one of BaO or SrO), and bismuth oxide (B
Since i ₂ O ₃₎ is configured to be contained 0.5～7Wt% to several hundred magnetic properties up to a high frequency band such MHz~GHz is available good, and Y-type hexagonal ferrite 1000 ° C, containing as little other phase as possible
Particularly, it is possible to provide a magnetic oxide sintered body that can be fired at around 900 ° C. and a high-frequency circuit component using the same.

[Brief description of the drawings]

FIG. 1 is a schematic drawing of an inductance element (high-frequency circuit component) used in an example.

[Explanation of symbols]

 10 terminal conductor 11 inner conductor 20 ferrite

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G018 AA01 AA09 AA10 AA22 AA24 AA37 AB03 AC16 5E041 AA06 AA19 BD01 CA01 HB01 NN01 NN02 NN06 NN18

Claims (5)

[Claims] 1. A magnetic oxide sintered body occupied by 80% or more of a Y-type hexagonal ferrite, wherein the magnetic oxide sintered body contains cobalt oxide as a main component.
3 to 15 mol% in terms of oO; copper oxide in terms of CuO;
5 to 17 mol%, iron oxide is 57 to 61 mol% in terms of Fe ₂ O ₃ , and the balance is AO (AO is at least one of BaO and SrO), and bismuth oxide (Bi ₂ O ₃ ) is used as a sub-component. 0.5 ~ 7w
A magnetic oxide sintered body characterized by containing t%. 2. The magnetic oxide sintered body according to claim 1, wherein a calcination temperature in the production of the magnetic oxide sintered body is 850 ° C. to 1000 ° C. 3. A high-frequency circuit component having a structure in which a conductor is embedded in a magnetic oxide sintered body, wherein the magnetic oxide sintered body is a Y-type hexagonal ferrite.
% Or more, and the magnetic oxide sintered body contains cobalt oxide as a main component.
3 to 15 mol% in terms of oO; copper oxide in terms of CuO;
5 to 17 mol%, iron oxide is 57 to 61 mol% in terms of Fe ₂ O ₃ , and the balance is AO (AO is at least one of BaO and SrO), and bismuth oxide (Bi ₂ O ₃ ) is used as a sub-component. 0.5 ~ 7w
A high-frequency circuit component characterized by containing t%. 4. The high-frequency circuit component according to claim 3, wherein a calcination temperature in the production of the magnetic oxide sintered body is 850 ° C. to 1000 ° C. 5. The high-frequency circuit component according to claim 3, wherein the conductor is mainly composed of silver (Ag).