JP2003272914A - Oxide magnetic material, manufacturing method of the same, and laminated chip inductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide magnetic material that is excellent in high-frequency performance, has a high insulation resistance, can prevent loss of internal conductor caused by diffused Ag, and is capable of being sintered by low- temperature baking; and to provide a method of manufacturing the material and a laminated chip inductor using the material. <P>SOLUTION: The oxide magnetic material contains a main component and an accessory component. The main component is composed of Fe<SB>2</SB>O<SB>3</SB>, of 43.0-51.0 mol%, CuO of 5.0-12.0 mol%, NiO of 8.0-39.0 mol%, and the balance of ZnO. The accessory component is composed of Bi<SB>2</SB>O<SB>3</SB>of 0.5-2.0 pts.mass, either one or both of MgO and CoO of 0.1-1.0 pts.mass in total, and either one or both of BeO and GeO of 0.05-0.3 pts.mass in total, assuming the contents of the main component is 100 pts.mass. In the method of manufacturing the magnetic material, the material is baked at a temperature of 830-900°C. The laminated chip inductor uses Ag as internal conductors and the oxide magnetic material as a soft ferrite. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ferrite, that is, a soft oxide magnetic material for a chip inductor used as a countermeasure for electromagnetic interference noise in a small electronic device or the like, a method for producing the same, and oxides thereof. The present invention relates to a laminated chip inductor using a magnetic material.

[0002]

2. Description of the Related Art In recent years, with the development of small OA devices or mobile communication devices represented by portable personal computers, mobile phones, etc., electronic parts mounted on these devices have been made smaller and have higher performance. And there is a strong demand for lower prices. One of those parts is a multilayer chip inductor used as an EMI noise filter.

An inductor corresponds to an element of a winding having an air core or a soft magnetic material as a core material, and the AC resistance or impedance based on the inductance increases as the frequency increases. Therefore, it has a function of a low-pass filter that allows a necessary signal to pass but blocks noise of a frequency higher than that signal, and is used for preventing electromagnetic interference between electronic devices and malfunction caused by external noise intrusion.

In recent years, due to the increase in the amount of information and the increase in signal processing speed, the frequency of the signal handled by the above-mentioned electronic equipment has become higher, and the digitization has advanced, so that the necessity of suppressing noise in a higher frequency range has increased. Is coming. On the other hand, these high-frequency signals may become noise in other devices that operate in a relatively low-frequency range.Therefore, in addition to preventing noise from entering from the terminals that connect to the outside, You have to make sure that the signal doesn't leak into. Under these circumstances, there is a need for a noise filter that operates effectively in a higher frequency range.

A multilayer chip inductor is an inductor that has been made smaller and has higher performance to be adapted to electronic circuit parts. An example of the internal structure is schematically shown in FIG. 1. Inside the soft ferrite 1 having a rectangular parallelepiped shape, a winding-shaped line of the conductor 3 is formed. It is connected to the input / output end electrodes 2 on both opposing surfaces. This is to print conductor paste lines on a soft ferrite green sheet, stack the sheets by filling the conductor paste in the through holes 5 etc. so that the conductor lines of each sheet are connected. It is manufactured by integrated firing.

The performance of such an inductor is largely controlled by the characteristics of soft ferrite, that is, a soft oxide magnetic material (hereinafter simply referred to as ferrite). The characteristics required for this ferrite are (1) In addition to having a sufficiently high permeability in the high frequency band used, (2)
It is important that a sufficient sintering density can be obtained at a low firing temperature, and (3) that it has a high electrical insulation resistance.

Ferrite has a composition represented by the form of XFe ₂ O ₄ , where X is Mn, Fe, Co, Ni or C.
It is a solid solution of an oxide which is one kind of u, Zn or the like, or a mixture of plural kinds of these elements. For example, X is Mn
Ferrite composed of Zn and Zn has an extremely high magnetic permeability. However, since this MnZn ferrite has a low electric insulation resistance and its magnetic permeability is excellent in a low frequency range, but is deteriorated in a high frequency range, it cannot be used for a chip inductor intended for use in a high frequency range. On the other hand, as ferrite showing high magnetic permeability in the high frequency band, Ni
There are Zn ferrite and CuNiZn ferrite.

In order to obtain a dense ferrite having a high magnetic permeability, it is usual to thoroughly mix raw materials, calcinate and synthesize at 700 to 1000 ° C., pulverize the raw material powder, and add a binder (binding material). After kneading and compression molding into a predetermined shape, baking is performed at a high temperature of 1000 ° C or higher. In the case of a laminated chip inductor, a metal conductor material serving as an internal conductor is printed on a green sheet before firing, the sheet is laminated and molded, and then the ferrite and the conductor are simultaneously fired to be integrated. Since firing is usually performed in the atmosphere, a metal that does not oxidize at a high temperature and has a melting point sufficiently higher than the firing temperature is used. If the melting point of the metal is low,
It flows out during firing or diffuses inside the ferrite,
This will reduce or eliminate the cross-sectional area of the inner conductor.

Ag-Pd alloy is often used as such an internal conductor. When Pd is contained in Ag, the melting point rises, so that melting and diffusion at a high temperature necessary for sintering ferrite can be suppressed, and further, a difference in thermal contraction with the ferrite after sintering can be reduced. However, Ag is P
If another metal element such as d is added, the conductivity decreases, and if it is used as a conductor, the internal resistance of the inductor increases. The increase of the internal resistance increases the insertion loss of the inductor, that is, the Q value which is a quality index is greatly reduced.

Further, it is necessary to sufficiently take measures against noise even in a large current portion such as a power source section.
High-speed connection terminals such as EEE1394 and USB2.0 share the power supply with the signal. When a multilayer chip inductor is used for a noise filter in a large current region, heat generation during use due to an increase in conductor resistance becomes a problem.

From this point of view, it is desirable that the internal resistance of the laminated inductor is as small as possible, and the conductor should be an Ag alloy in which the content of other metal elements such as Pd is suppressed to a low level. Is. However, the melting point of Ag is as low as 961 ° C, and in order to use Ag metal simple substance as the internal conductor, the firing temperature of the laminated inductor or ferrite must be suppressed to 920 ° C even at a high temperature. A ferrite material that can be bonded is needed.

[0012] For example, Japanese Patent Publication No. 7-87149 discloses a
Disclosed is an invention of a multilayer chip impedance element in which g is an internal conductor, CuNiZn ferrite is a main component, and at least one of Bi ₂ O ₃ , V ₂ O _{5, and} lead silicate glass is added as a second component. ing. Although it is shown that the permissible current was increased by setting the firing temperature to 900 ° C. using an Ag conductor, the composition of the component is only an example and its range limit is unknown. The performance as a chip inductor has not been clarified.

The ferrite used for the laminated chip inductor must have the highest electric insulation resistance.
This is because the internal metal conductor is in direct contact with the ferrite, so that if the insulation resistance decreases, the leakage current between the internal conductors and between the input and output terminals increases, and the effective value of the inductance decreases. In addition, a decrease in insulation resistance causes an eddy current inside the ferrite, which not only decreases the inductance but also decreases the Q value, resulting in an increase in insertion loss. Further, the inductor itself serves as a source of noise reception and transmission, which may cause malfunction of the circuit.

The insulation resistance of ferrite greatly depends on its composition. As described above, MnZn ferrite exhibits extremely high magnetic permeability, but since the insulation resistance is not high, NiZn ferrite or CuNiZn ferrite that can be sintered at a lower temperature is used for high frequencies.

As an example in which this CuNiZn ferrite is used, especially considering the increase of insulation resistance, Japanese Patent Application Laid-Open
There is an invention presented in Japanese Patent Publication No. 6-295811. This invention is MoO
_{Although a} small amount of ₃ is added to improve the magnetic permeability, the amount of Fe ₂ O ₃ is limited to the range of 48 to 50 mol% to improve the insulation resistance. In addition, the invention disclosed in Japanese Patent Laid-Open No. 11-219812 includes CuNiZn ferrite with M
In this case, the content of Fe ₂ O ₃ is 48
Controlled within a narrow range of ~ 49.5 mol% to achieve high insulation resistance.

In these two inventions, a sintered density of sufficiently high and a resistivity of 1 × 10 ⁴ MΩcm or more is also presented,
Excellent ferrite is obtained. However, in any case, firing is performed at a temperature of 950 to 1300 ° C. If sufficient characteristics cannot be exhibited unless firing is performed at such a temperature, a laminated chip using a metal Ag simple substance as an internal conductor Not applicable to inductors.

[0017]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a multilayer chip inductor having a low internal resistance and adapting to a large current specification and having excellent high frequency performance. That is,
Oxide magnetic material which uses Ag for the inner conductor and can be sintered at a low temperature for that reason, and which can obtain high magnetic permeability and high insulation resistance in a high frequency range, a method for producing the same, and a laminated chip inductor using the oxide magnetic material Is provided.

[0018]

An inner conductor of a laminated chip inductor is printed on a ferrite green sheet in the form of a paste-like material, and after drying, the sheets are laminated by pressure bonding and integrally fired. At the same time, the sintering is performed.

In order to make this internal conductor a single body of metal Ag, first, the required firing temperature of the Ag paste was investigated. As a result, the sintering of the Ag paste on the green sheet progressed sufficiently, and the firing temperature at which the electric conductivity of the conductor was maximized was 830 to 900 ° C.
Was confirmed. Above this temperature range, Ag easily diffuses and reacts, causing a decrease in cross-sectional area and invasion of other elements. Below this temperature, sintering becomes insufficient, and in any case, inside the inductor. The electric resistance value as a conductor increases.

The ferrite is required to be capable of being sinter sufficiently densely in the firing temperature range of this Ag paste to have high magnetic permeability and exhibiting the highest possible insulation resistance. Therefore, it is decided to study whether the ferrite having such characteristics can be obtained or not, and to examine the composition thereof.
The magnetic permeability was 5.0 g / cm ³ or more, the magnetic permeability at 1 MHz was 300 or more, and the resistivity was 1000 MΩcm or more.

First, CuNiZ is considered to be excellent in magnetic characteristics such as magnetic permeability in a high frequency range and to lower the sintering temperature.
Fe ₂ O ₃ , NiO, Zn based on n-ferrite
By changing the compounding ratio of O and CuO variously, the possibility of lowering the sintering temperature and securing the insulation resistance within the range where the magnetic characteristics can be sufficiently secured was examined. However, by changing the composition ratio by only these components, the firing temperature for sufficiently increasing the sintering density could not be lowered to the temperature range in which the Ag conductor can be used. Then, next, the subcomponent added as an auxiliary agent was examined.

It is important that the subcomponents not only lower the sintering temperature but also improve the insulation resistance of the obtained ferrite, and that they do not interact with Ag of the conductor.

From such a viewpoint, as a result of adding various subcomponents and investigating the effect thereof, it was found that the inclusion of Bi ₂ O ₃ is extremely preferable for lowering the sintering temperature. Bi ₂
O ₃ has a melting point near the sintering temperature of the Ag paste,
It is presumed that the formation of a slight liquid phase promotes low temperature sintering.

In addition to Bi ₂ O ₃ , MgO,
It has been found that the inclusion of CoO, BeO and GeO greatly improves the insulation resistance. All of these metal elements serving as oxides become divalent cations, and their ionic radius is close to that of Fe ³⁺ .

Ferrite has a spinel type crystal structure (AB
₂ O ₄ ) has a reverse spinel type crystal structure in which a trivalent ion enters in the A position and divalent and trivalent ions enter in the B position. In the electroconductivity, in the inverted spinel type crystal structure, the Fe atom at the position of B can take the form of divalent and trivalent ions, so that an electron exchange reaction of Fe ²⁺ = Fe ³⁺ + e ⁻ occurs, resulting in an electron exchange reaction. It is speculated that this is due to the movement of. Fe
^If there are divalent ions close to the ion radius of ³⁺ , F
It is considered that it is substituted with e ³⁺ and enters the B position to suppress the above-mentioned electron exchange reaction and increase the insulation resistance.

As a result of further investigation of the contents and effects of these four kinds of components, it was found that MgO and CoO, and Be.
Dividing into two groups of O and GeO, selecting one or two kinds of components in each group, and including these two groups of components at the same time makes the insulation resistance higher and the burning of Bi ₂ O ₃ is performed. It became clear that the effect of lowering the freezing temperature was not hindered. Rather than increasing the insulation resistance with only one component, it is more effective to add a plurality of components little by little even if the total content is the same.

From the above-mentioned examination results, the composition which can obtain almost the target sintering density, magnetic permeability and resistivity was clarified. Therefore, the composition range limits and the manufacturing conditions are clarified. Then, a multilayer chip inductor was manufactured, the performance was confirmed, and the present invention was completed. The gist of the present invention is as follows.

(1) Fe ₂ O ₃ : 43.0 to 51.0 mol%, Cu
O: 5.0 to 12.0 mol%, NiO: 8.0 to 39.0 mol%, and ZnO: the balance of the main component, and 100 parts by mass of this main component, Bi ₂ O ₃ : 0.5 to 2.0 parts by mass as a sub-component, Co
0.1 to 1.0 parts by mass of one or both of O and MgO and one or both of BeO and GeO are combined.
An oxide magnetic material comprising 0.05 to 0.30 parts by mass.

(2) Characteristically that the raw materials are mixed and calcined and synthesized, and the pulverized and sized powder is mixed with a binder to be kneaded into a desired shape and then fired at 830 to 900 ° C. for 1 to 5 hours. The method for producing an oxide magnetic material according to (1) above.

(3) A laminated chip inductor comprising an Ag inner conductor and the oxide magnetic material according to claim 1.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the reason for limiting the composition of ferrite as described above is as follows. Here, the composition ratios of the respective components are defined as being in a divalent or trivalent state in the form of oxide, but these do not indicate the form of the element in the oxide magnetic material.

Fe ₂ O ₃ is a basic component of ferrite and must constitute 43.0 to 51.0 mol% of the main component of ferrite. If it is less than 43.0 mol%, sufficient magnetic permeability cannot be obtained, and the impedance of the multilayer chip inductor becomes insufficient. On the other hand, if it exists in excess of 51.0 mol%, a sufficient sintered density cannot be obtained and the insulation resistance also becomes low. In addition, the mechanical strength of the multilayer chip inductor element is insufficient, and there is a possibility that resistance to performance deterioration due to long-term use, that is, deterioration of weather resistance may result.

CuO is one of the main components of ferrite.
It is assumed that it constitutes 0 to 12.0 mol%. CuO is
It greatly contributes to the lowering of the sintering temperature, and when it is less than 5.0 mol%, the sintering density becomes insufficient when firing in the low temperature range targeted by the present invention, and in addition to insufficient mechanical strength. It causes poor weather resistance. On the other hand, if it exceeds 12.0 mol%, a glassy mixed phase is formed on the surface during firing and is easily welded to the holding base, which lowers productivity and also lowers insulation resistance.

NiO is contained in order to secure the magnetic permeability of ferrite in the high frequency range. The amount is 8.0 mol%
If it is less than the above value, or conversely, if it is too much and exceeds 39.0 mol%, the magnetic permeability in the high frequency range will decrease, so the content of ferrite in the main component is limited to 8.0 to 39.0 mol%.

ZnO is an important element for improving the magnetic permeability of ferrite.
_The remaining portion excluding ₂ O ₃ , CuO and NiO shall be constituted. However, the content ratio is 6.0 mol%
If it is less than 1.0, problems such as insufficient magnetic properties of the obtained ferrite and insufficient sintering density will occur, and conversely, if it exceeds 36.0 mol%, the magnetic properties will deteriorate, so a desirable range is from 6.0 to 36.0 mol%. Is to

With respect to the main component constituting the above ferrite, an auxiliary component having the following composition is contained as an auxiliary agent. The content of each subcomponent is shown in parts by mass when the total amount of the main components of the above ferrite is 100 parts by mass.

Bi ₂ O ₃ has the effect of promoting the sintering of ferrite at low temperatures, and is contained in an amount of 0.5 to 2.0 parts by mass. B
When the amount of i ₂ O ₃ is less than 0.5 part by mass, the sintering is insufficient at the firing temperature of 830 to 900 ° C., and the sintered density and magnetic permeability cannot be obtained. On the other hand, when the amount exceeds 2.0 parts by mass, the cross-sectional area of the Ag conductor after firing becomes remarkable, which may increase the internal resistance, or the conductor function may be lost due to the disappearance of the conductor.

One or both of MgO and CoO as a subcomponent are contained in a total amount of 0.1 to 1.0 parts by mass. MgO
Although CoO and CoO increase the insulation resistance of low temperature fired ferrite, the effect is the same for all components. If this total amount is less than 0.1 parts by mass, the effect of improving the insulation resistance cannot be obtained, and if it exceeds 1.0 parts by mass, the magnetic permeability decreases and sintering becomes impossible.

The subcomponent further contains one or both of BeO and GeO in a total amount of 0.05 to 0.30 parts by mass. All of these components have the effect of increasing the insulation resistance, and particularly when they are contained in the presence of MgO and CoO, the effect is exhibited. If the total amount is less than 0.05 parts by mass, the effect of increasing insulation resistance does not appear. However, if the content is too large and exceeds 0.30 parts by mass, sintering at low temperature becomes impossible.

In addition to the above-mentioned components, Ag ₂ O is further added as a subsidiary component.
Alternatively, when one or both of Rh ₂ O ₃ is contained, the diffusion of Ag during firing is suppressed, and the reduction of the cross-sectional area of the Ag internal conductor can be reduced. Therefore, it is preferable to include these oxides as needed.
In that case, since the bad effects and is too much without the sinterability the less, Ag 2 _O in 0.01 to 0.07 parts by mass, Rh ₂ O
_In No. ₃ , the range is 0.2 to 1.5 parts by mass. These ingredients are
It is preferable to add other components to the calcined synthetic powder after mixed and calcined to produce a green sheet, and perform integrated firing.

In addition to the above composition, some impurities can be mixed as long as the characteristics of ferrite are not significantly affected.

The above-mentioned ferrite may be manufactured according to a general method of manufacturing an oxide magnetic material, but the manufacturing of a laminated chip inductor will be described below as an example. First, mix the main component and subcomponents in the atmosphere.
It is calcined at a temperature of around 800 ° C, and the calcined powder is crushed and sized. A binder is added to this sized powder and sufficiently kneaded to form a green sheet by a doctor blade method or the like.

The conductor paste is printed on the green sheet, the sheets are laminated, cut into a predetermined shape, and then fired at 830 to 900 ° C. for 1 to 5 hours. If the firing temperature is lower than 830 ° C, the magnetic properties and mechanical strength will be poor due to insufficient sintering, and if it exceeds 900 ° C, the internal conductor will become thin or disappear, and a good chip inductor will be obtained. You won't get it. If the firing time is less than 1 hour, sintering will be insufficient.
On the other hand, even if the heating is continued more than necessary, almost no improvement in performance is observed, and the heating time and energy are wasted, so the maximum is 5 hours. After firing, the input / output end electrodes are attached to the conductor portion connected to the internal conductor to form a chip inductor.

[0044]

Example 1 A ball mill using zirconia grinding balls together with 1 liter of pure water, in which the raw materials having the blending composition ratios shown in Table 1 were weighed so that the total amount was 250 g. After mixing for 24 hours in the same place, it was dried, transferred to a zirconia crucible and calcined at 800 ° C in the atmosphere. After calcination, it was confirmed by X-ray diffraction that a spinel type cubic compound was obtained.

The obtained calcined synthetic powder was wet pulverized in a ball mill, dried, and sized by a mesh sieve so that the particle size became 0.8 to 1.0 μm. 10 mass% as a binder for this
PVA (polyvinyl alcohol) solution was added, granulated with a liquor machine, and the granulated powder was pressed with a mold and molded, and then fired in the atmosphere at 850 ° C for 2.0 hours to obtain an outer diameter. A toroidal test piece having a diameter of 16 mm, an inner diameter of 8 mm and a thickness of 3 mm and a cylindrical test piece having an outer diameter of 10 mm and a thickness of 3 mm were prepared.

An impedance measuring device (HP4291 manufactured by Hewlett-Packard Japan, Inc.) was used for the toroidal shape test piece.
A) and a magnetic permeability measuring device (HP16454A manufactured by Hewlett-Packard Japan) were used to determine the magnetic permeability at 1 MHz. In addition, the density was measured by a liquid immersion weighing method using a cylindrical test piece, and an In-Ga alloy was adhered to the upper and lower surfaces to serve as electrodes, and a DC constant voltage power source (HP4140B manufactured by Hewlett-Packard Japan) was used. Then, the insulation resistance of DC 50V for 1 minute was measured, and the resistivity was calculated from the electrode area and the distance between the electrodes. The results are shown in Table 1.

[0047]

[Table 1]

The occurrence of Ag diffusion was investigated by making a laminated body having the same shape as the laminated chip inductor. Using 10% by mass of PVB (polyvinyl butyrate) as a binder in the above calcined synthetic powder, a green sheet having a thickness of 70 μm was prepared by the doctor blade method, and an Ag single composition as an internal conductor was formed on the sheet surface as an internal conductor. Paste the line width 150μm,
Print with a pattern equivalent to the internal conductor with a thickness of 20 μm, put a green sheet without printing on it, stack 4 layers of this and cut it into a chip shape after crimping, 900 ° C in air at 2.0 ° C
Baking for hours. After firing, the cross section of this test piece was polished and the shape of the conductor was observed with a scanning electron microscope. The results are also shown in Table 1.

As is clear from the results shown in Table 1, ferrite having a composition ratio of the main component and an amount of the subcomponents within the ranges defined in the present invention has high density and magnetic permeability and high resistivity. Has been obtained. That is, in the temperature range in which the Ag paste that becomes the internal conductor is sintered, the initially targeted sintering density is 5.0 g / cm ³ or more, and the magnetic permeability at 1 MHz is 3
It is a ferrite with a resistivity of 00 or more and a resistivity of 1000 MΩcm or more. Further, in these ferrites having compositions within the scope of the present invention, Ag diffusion was not observed even when firing was performed at 900 ° C., which is considered to be the upper limit temperature when Ag alone is used as an internal conductor.

Example 2 Using a ferrite calcined powder having the composition of Sample No. 5 shown in Table 1, PVB was used as a binder to prepare a 70 μm thick green sheet by the doctor blade method. On the surface of the sheet, a paste of Ag single composition as an internal conductor is printed by a predetermined pattern with a print line width of 150 μm and a thickness of 20 μm, and laminated to have an internal structure as schematically shown in FIG. A chip inductor was formed. The tip in this case is 2125 size (length 2.0 mm,
The width was 1.25 mm and the thickness was 0.5 mm), the number of conductor turns inside was 8, and the conductor connection between the laminated sheets was through holes.

The sheets were laminated and pressure-bonded, cut into the above-mentioned chip size, and fired at 900 ° C. for 2.0 hours in the atmosphere.
The magnetic permeability of the ferrite in this case was 330 (1 MHz).

Input and output electrodes were attached to both ends of the fired chip, and the impedance was measured by the impedance measuring device used in Example 1. The allowable current value was the maximum current value at which the surface temperature rise was within + 3 ° C by gradually increasing the current flowing between both electrodes. These results are as follows.

Impedance | Z |: 1000 Ω (100 MHz) Maximum allowable current Ip: 3.0 A As described above, the multilayer chip inductor according to the present invention exhibits high impedance and the allowable current value is sufficiently large.

[0054]

INDUSTRIAL APPLICABILITY The oxide magnetic material of the present invention, that is, soft ferrite, can be sintered by firing at a lower temperature than conventional ones, has a sufficiently high magnetic permeability even in a high frequency region, and has an insulation resistance. And the loss of the internal conductor due to Ag diffusion can be suppressed. This multilayer chip inductor made of ferrite can use Ag with a low electric resistance for the internal conductor, so it is particularly suitable for large current specifications, has excellent high frequency characteristics, and has a low internal resistance, which improves the performance of electronic equipment. Can be used effectively.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating a structure of an internal conductor of a multilayer chip inductor.

[Explanation of symbols] 1. Laminated sintered body part of ferrite 2. Input and output end electrodes 3. Inner conductor 4. Conductive part connected to input / output electrodes 5. Through hole for connection between inner conductors

Claims (3)

[Claims] 1. Fe ₂ O ₃ : 43.0 to 51.0 mol%, CuO:
5.0-12.0 mol%, NiO: 8.0-39.0 mol% and Zn
O: a main component the balance, to the main component of 100 parts by mass, as an accessory component _Bi 2 _{O 3: 0.5~2.0} parts by weight, CoO
0.1 to 1.0 parts by weight of one or both of MgO and MgO and one or both of BeO and GeO of 0.
An oxide magnetic material, characterized by containing 05 to 0.30 parts by mass. 2. A raw material is mixed and calcined and synthesized, and a pulverized and sized powder is added with a binder and kneaded to form a desired shape.
The method for producing an oxide magnetic material according to claim 1, wherein the firing is performed at 830 to 900 ° C. for 1 to 5 hours. 3. A laminated chip inductor comprising an Ag inner conductor and the oxide magnetic material according to claim 1.