JP3174398B2 - Ferrite sintered body, chip inductor parts, composite laminated parts and magnetic core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite sintered body used as various magnetic materials, a chip inductor using the sintered body as a magnetic material, a composite laminated part such as an LC composite part, and a magnetic core.

[0002]

2. Description of the Related Art Various ferrites have been used as various magnetic core materials and composite laminated parts because of their excellent magnetic properties.

[0003] The laminated LC composite component is composed of a capacitor chip body formed by laminating a ceramic dielectric layer and an internal electrode layer, and an inductor chip body formed by laminating a ferrite magnetic layer and an internal conductor. It was formed in a typical manner.

[0004] Such composite laminated parts are widely used in various electronic devices because of their small volume, high robustness and high reliability.

[0005] These components, for example, LC composite components, are usually laminated and integrated by a thick film technique with an internal conductor paste, a magnetic layer paste, a dielectric layer paste and an internal electrode layer paste, and then fired. It is manufactured by printing or transferring an external electrode paste on the surface of the obtained sintered body, and then firing. In this case, the magnetic material used for the magnetic layer may be Ni
—Cu—Zn based ferrite and Ni—Zn based ferrite are generally used.

However, when a ferrite such as a Ni—Cu—Zn ferrite is used as a magnetic material of a chip inductor,
The inductance L depends on the type of nickel oxide or iron oxide as the raw material, that is, whether or not they are of high purity, and in particular, how much the impurity P ₂ O ₅ is contained.
And Q were found to be greatly affected. Such a tendency also appeared when the above-mentioned raw material was used for a magnetic core.

The present inventors have studied such a phenomenon, and found that by controlling the content of P contained in the ferrite raw material to a specific range, the characteristics of μi, L and Q in the magnetic core and the chip inductor were controlled. That we can maintain or improve.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to set the content of P in ferrite in a ferrite sintered body within a predetermined range to maintain μi, L and Q at high values. .

[0009]

This and other objects are achieved by the present invention which is defined below as (1) to (5). (1) A ferrite sintered body containing two or three of Ni, Cu and Zn, wherein P is added to ferrite in a raw material stage in a range of 8 to 90 ppm in terms of P. Ferrite sintered body.

(2) The ferrite composition is Fe ₂ O ₃ : 4
0 to 52 mol%, NiO: 0 to 50 mol%, Cu
O: 0 to 20 mol% and ZnO: 0 to 50 mol%
The ferrite sintered body according to the above (1).

(3) A chip inductor component having an inductor portion formed by laminating a ferrite magnetic layer and an internal conductor, wherein the ferrite magnetic layer is made of the ferrite sintered body of (1). A chip inductor component characterized by the above-mentioned.

(4) A composite laminated component having at least a chip inductor portion formed by laminating a ferrite magnetic layer and an internal conductor, wherein the ferrite magnetic layer is made of the ferrite sintered body of the above (1). Composite laminated parts characterized by the following.

(5) A magnetic core comprising the ferrite sintered body of (1).

[0014]

In the ferrite sintered body of the present invention, the content of the P component in the ferrite component as a raw material is 8 to 90 ppm in terms of P.
, Preferably 10 to 80 ppm. When the content of the P component exceeds 90 ppm, μi and L are remarkably reduced. on the other hand,
Even if the content of P is less than 8 ppm, μi, L and Q are reduced, which is not preferable. The P component is generally mixed as P ₂ O ₅ . A composite laminated component having at least a ferrite chip inductor component using such a ferrite sintered body has excellent performance and can have many uses as an electronic component. Note that P in the magnetic layer may be calculated by separating the magnetic layer, pulverizing the magnetic layer, and then performing X-ray fluorescence analysis.

[0015]

[Specific Configuration] Hereinafter, a specific configuration of the present invention will be described in detail. FIG. 1 shows a laminated LC composite component which is a preferred embodiment of the composite laminated component of the present invention.

An example of the LC composite component 1 of the present invention shown in FIG. 1 is a capacitor chip 2 formed by laminating a ceramic dielectric layer 21 and an internal electrode layer 25, a ferrite magnetic layer 31, and an internal conductor 35. And an inductor chip body 3 formed by laminating the above-mentioned components, and has an external electrode 51 on the surface.

As the material of the ferrite magnetic layer 31 of the inductor chip body 3, a ferrite containing two or three of Ni, Cu, and Zn as main components, such as a Ni—Cu—Zn ferrite, is used.

The ferrite used in the present invention is Ni
-Cu-Zn, Ni-Cu, Ni-Zn, if any one of Cu-Zn, is not particularly limited otherwise, may be selected having various compositions depending on the purpose, Fe ₂ O
₃ : 40 to 52 mol%, especially 45 to 50 mol%, N
iO: 0 to 50 mol%, CuO: 0 to 20 mol%,
Especially 5 to 20 mol% and ZnO: 0 to 50 mol
%, Particularly preferably 0 to 35 mol%.

In addition, Co, Mn, etc. may be contained in an amount of about 5 wt% or less of the whole, and Ca, Si, Bi,
V, Pb and the like may be contained in an amount of about 1 wt% or less.

In the present invention, the conductive material constituting the inner conductor 35 needs to have a low resistivity in order to obtain a practical Q as an inductor. preferable. At this time, it is preferable to use pure silver having a silver content of 90% by weight or more, particularly preferably 99.9% by weight or more. In this way, the specific resistance can be extremely reduced by using pure silver.

Inductor chip body 3 of LC composite part 1
May have a conventionally known structure, and the outer shape is usually a substantially rectangular parallelepiped shape. As shown in FIG. 1, the internal conductor 35 is usually arranged in a spiral shape in the magnetic layer 31 to form an internal winding, and both ends of each of the external electrodes 51,
51. In such a case, the inner conductor 35
, That is, the closed magnetic circuit shape can be various patterns, and the number of turns may be appropriately selected according to the application. The dimensions of each part of the inductor chip body 3 are not limited, and may be appropriately selected according to the application.

The thickness of the inner conductor 35 is usually 5 to 3
0μm, winding pitch is usually about 10-400μm,
The number of turns is usually about 1.5 to 50.5 turns. The base thickness of the magnetic layer 31 is usually about 100 to 500 μm, and the thickness of the magnetic layer between the internal conductors 35 is usually 10 to 10 μm.
It is about 0 μm.

The ceramic dielectric layer 21 of the capacitor chip body 2 is not particularly limited, and various dielectric materials may be used. However, since the firing temperature is low, it is preferable to use a titanium oxide-based dielectric. In addition, a titanate-based composite oxide, a zirconate-based composite oxide, or a mixture thereof can also be used. Further, in order to lower the firing temperature, a glass such as borosilicate glass may be contained.

Specifically, as the titanium oxide, NiO, CuO, Mn ₃ O ₄ , Al ₂ O ₃ , Mg
O, SiO _{2 and the} like, particularly TiO ₂ containing CuO, etc., are used as titanate-based composite oxides such as BaTiO ₃ and SrTiO.
₃ , CaTiO ₃ , MgTiO ₃ and mixtures thereof,
BaZrO ₃ , Sr
Examples include ZrO ₃ , CaZrO ₃ , MgZrO _3, and mixtures thereof.

In the present invention, there is no particular limitation on the conductive material constituting the internal electrode layer 25, and Ag, Pt, Pd, Au,
Cu, Ni or, for example, Ag-Pd alloy
It may be selected from alloys and the like containing at least one kind, but in particular A
g, an Ag alloy such as an Ag-Pd alloy, or the like is preferable.

The capacitor chip 2 of the LC composite component 1
May have a conventionally known structure, and the outer shape is usually a substantially rectangular parallelepiped shape. Then, as shown in FIG. 1, one end of the internal electrode layer 25 is connected to the external electrode 51. There are no particular restrictions on the dimensions of each part of the capacitor chip body 2,
What is necessary is just to select suitably according to a use etc.

The number of stacked dielectric layers 21 may be determined according to the purpose, but is usually about 1 to 100. Also,
The thickness per dielectric layer 21 is usually 20 to 150
μm, and the thickness per layer of the internal electrode layer 25 is usually about 5 to 30 μm.

The conductive material forming the external electrode 51 of the LC composite component 1 of the present invention is not particularly limited.
t, Pd, Au, Cu, Ni, or an alloy containing at least one of these, such as an Ag-Pd alloy, may be selected.
In particular, Ag and Ag alloys such as Ag-Pd alloy are suitable. The shape and dimensions of the external electrode 51 are not particularly limited, and may be appropriately determined depending on the purpose and application, but the thickness is usually about 100 to 2500 μm.

The dimensions of the LC composite part 1 of the present invention are not particularly limited, and may be appropriately selected according to the purpose and application, but are usually (1.6 to 10.0 mm) × (0.8 to 15). .0
mm) × (1.0 to 5.0 mm).

The composite laminated component of the present invention is not limited to the above-described LC composite component, but may be any of various other composite laminated components as long as they have the above-described configuration in part. The composite laminated component such as the LC composite component 1 of the present invention can be manufactured by a normal printing method using a paste or a sheet method.

The ferrite magnetic layer paste is prepared as follows. First, raw powder of ferrite, for example, various powders such as NiO, ZnO, CuO, Fe ₂ O ₃
A predetermined amount is wet-mixed with a ball mill or the like. At this time, a predetermined amount of P ₂ O ₅ set within the range of the present invention is added simultaneously and mixed together. The particle size of the raw material powder used is 0.1 to 1
It is about 0 μm. Further, P of the raw material powder can be easily measured by the above-described chemical analysis.

The wet-mixed product is usually dried by a spray drier and then calcined. This is usually wet-pulverized by a ball mill until the powder particle size becomes about 0.01 to 0.5 μm, and dried by a spray drier.

The obtained ferrite powder is kneaded with a binder such as ethyl cellulose and a solvent such as terpineol and butyl carbitol to form a paste.

The magnetic layer paste may contain various glasses and oxides as necessary.

The composition of the ceramic dielectric layer paste is not particularly limited, and various dielectric materials or raw material powders to be dielectric by firing are selected according to the composition of the ferrite dielectric layer as described above, and various binders and It may be prepared by kneading with a solvent.

As the raw material powder, an oxide constituting a titanium oxide-based or titanic acid-based composite oxide or the like may be used, and depending on the composition of the corresponding oxide dielectric, Ti, B
An oxide such as a, Sr, Ca, or Zr may be used. In addition, compounds that become oxides by firing such as carbonates, sulfates, nitrates, oxalates, and organometallic compounds may be used. These raw material powders usually have an average particle diameter of about 0.1 to 5 μm. Further, if necessary, various glasses may be contained. Further, various glasses or oxides may be contained as necessary as a sintering aid or the like.

The paste for the internal conductor, the paste for the internal electrode layer, and the paste for the external electrode are respectively the above-mentioned various conductive metals, alloys, or various oxides, organometallic compounds, resinates which become the above-mentioned conductive materials after firing. Are kneaded with the above-mentioned various binders and solvents.

The contents of the binder and the solvent in each of the above-mentioned pastes are not particularly limited.
The binder may be about 1 to 5 wt%, and the solvent may be about 10 to 50 wt%. Further, each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like, as necessary. Their total content is
It is preferably at most 10 wt%.

In manufacturing the LC composite component 1, for example, first, a paste for a magnetic layer and a paste for an internal conductor are laminated and printed on a substrate such as PET.

A green sheet is formed using a magnetic layer paste or a dielectric layer paste, and an internal conductor paste or an internal electrode layer paste is printed thereon. It may be formed. In this case, the dielectric layer adjacent to the magnetic layer may be printed directly.

Next, the paste for the external electrode is printed or transferred onto the green chip, and the paste for the magnetic layer, the paste for the internal conductor, the paste for the dielectric layer, the paste for the internal electrode layer, and the paste for the external electrode are simultaneously fired. Alternatively, the chip body may be baked first, and then the paste for external electrodes may be printed and baked.

The firing temperature is from 800 to 930 ° C., especially 85
The temperature is preferably set to 0 to 900 ° C. The firing time is preferably 0.05 to 5 hours, particularly preferably 0.1 to 3 hours. The firing is performed at PO ₂ = 1 to 100%.
The firing temperature for baking the external electrode is usually 50
The firing time is usually about 10 minutes to 3 hours at about 0 to 700 ° C., and the firing is usually performed in the air.

In the present invention, it is preferable that the heat treatment be performed in an atmosphere containing oxygen in excess of the atmosphere during and after firing. By performing a heat treatment in an oxygen-excess atmosphere, a substance precipitated in the form of a metal such as Cu or Zn or an oxide having a low resistance such as Cu ₂ O or Zn ₂ O or a substance that has been precipitated is reduced to Cu.
It can be deposited in the form of an oxide having high resistance such as O and ZnO and having no harm. Therefore, the circuit resistance of the component is further improved. Further, it is preferable that the heat treatment is performed at the time of the last firing and after the last firing.

For example, in the case where firing of the chip body and firing for firing the external electrode are performed simultaneously, the firing for firing the external electrode is performed at the time of firing and after the firing, and after firing of the chip body. It is preferable to perform a predetermined heat treatment when the external electrodes are baked or after the external electrodes are baked. When the baking is performed twice as in the latter case, heat treatment may be further performed at the time of firing the chip body or after the firing of the chip body depending on the case.

The oxygen partial pressure ratio in the heat treatment atmosphere is 20 to 1
00%, more preferably 50 to 100%, particularly preferably 100%. Below the above range, Cu, Z
The ability to suppress the precipitation of n, Cu ₂ O, Zn ₂ O, etc. decreases.

Since such heat treatment in an oxygen-excess atmosphere is usually carried out simultaneously with the firing and the baking of the external electrodes, various conditions such as the heat treatment temperature and the holding time are the same as those of the baking conditions and the external electrode baking conditions. However, when only the heat treatment is performed alone, the heat treatment temperature is 550 to 900 ° C.
In particular, 650-800 ° C, holding time 0.5-2 hours,
It is particularly preferable to set the time to 1 to 1.5 hours.

In the case of a composite laminated component other than the LC composite component, it may be manufactured as described above. The composite laminated component of the present invention such as the LC composite component manufactured as described above is mounted on a printed circuit board or the like by performing soldering or the like on external electrodes, and is used for various electronic devices and the like.

[0048]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

The following pastes were prepared. (Paste for magnetic layer) Fe ₂ O _{3 in} final composition: 49.
0 mol%, NiO: 7.5 mol%, CuO: 13.2 mol% and ZnO: the raw material so that 30.3 mole% was mixed, 0～390Ppm the P ₂ O ₅ to simultaneously (P
In the range of 0 to 170 ppm). These are wet-mixed using a ball mill, and then the wet mixture is dried with a spray drier, calcined at 700 ° C., granules are wet-pulverized with a ball mill, and then dried with a spray drier. Ni-Cu-Zn ferrite raw material powder having an average particle size of 0.1 to 0.3 µm was obtained.

Next, 3.84 parts by weight of ethylcellulose and 78 parts by weight of terpineol were added to 100 parts by weight of the raw material powder, and kneaded with a three-roll mill to obtain a paste.

(Paste for internal conductor) Average particle size 0.8 μm
2.5 g of ethyl cellulose per 100 parts by weight of Ag
Parts by weight and 40 parts by weight of terpineol were added and kneaded with a three-roll mill to obtain a paste.

The paste for the magnetic layer and the paste for the internal conductor thus produced are printed and laminated, and various laminated monolithic chip inductors having different P contents as shown in Table 1 are obtained by the print lamination method. Manufactured.

In this case, the firing temperature was 870 ° C., the firing time was 2 hours, and the firing atmosphere was air.

The dimensions of the obtained multilayer chip inductor were 4.5 mm × 3.2 mm × 1.1 mm and the number of turns was 9.5 turns.

Further, a toroidal core was manufactured under the same firing conditions using the ferrite raw material powder for a test. The outer diameter of this toroidal core was 11.1 mm, the inner diameter was 5.1 mm, the thickness was 2.4 mm, the number of turns was 20 turns, and the wire diameter was 0.35 mm.

For these laminated chip inductors and toroidal cores, μi, L (μH) and Q were determined under the conditions of a measurement frequency of 400 kHz. Also, for the toroidal core, this power loss is converted to a frequency of 480 kHz.
z and the magnetic flux density were measured under the conditions of 20 mT. Table 1 also shows the obtained results.

[0057]

[Table 1]

As can be seen from the results shown in Table 1, when the addition amount of P is within the range of the present invention, the LQ product of the multilayer chip inductor and the μiQ product of the toroidal core are compared with the case of no addition or excess. Is improving. When the addition amount of P is within the range of the present invention, the value of the power loss of the toroidal core is also small.
At the time of ppm, it is improved by 30% as compared with the case of no addition. Therefore, from this, the effect of the present invention that regulates the amount of the P component within a specific range is apparent.

[0059]

According to the ferrite sintered body of the present invention, by setting the content of P in ferrite within a predetermined range,
When this is used for a magnetic core or a laminated chip inductor, μi, inductances L and Q are kept at high values, and the value of power loss of the magnetic core can be kept small. Therefore, a composite laminated component having at least such a ceramic inductor component has excellent performance and is useful for various electronic devices.

[Brief description of the drawings]

FIG. 1 is an LC showing a preferred embodiment of a composite laminated part according to the present invention.
It is sectional drawing in which a composite component is shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LC composite component 2 Capacitor chip body 21 Ceramic dielectric layer 25 Internal electrode 3 Inductor chip body 31 Ferrite magnetic layer 35 Internal conductor 51 External electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C04B 35/30 H01F 17/00 D H01F 17/00 41/02 D 41/02 C04B 35/26 J (58) Fields surveyed ( Int.Cl. ⁷ , DB name) H01F 1/34 C01G 49/00 C04B 35/26 C04B 35/28 C04B 35/30 H01F 17/00 H01F 41/02

Claims (5)

(57) [Claims] 1. A ferrite sintered body containing two or three of Ni, Cu and Zn, wherein P is added to ferrite in a raw material stage in a range of 8 to 90 ppm in terms of P. Ferrite sintered body. 2. The ferrite composition according to claim 2, wherein the composition of Fe ₂ O _{3 is} 40-.
52 mol%, NiO: 0 to 50 mol%, CuO: 0
2. The ferrite sintered body according to claim 1, wherein the content of ZnO is 0 to 50 mol%. 3. A chip inductor component having an inductor portion formed by laminating a ferrite magnetic layer and an internal conductor, wherein the ferrite magnetic layer is made of the ferrite sintered body according to claim 1. Characterized chip inductor parts. 4. A composite laminated component having at least a chip inductor portion formed by laminating a ferrite magnetic layer and an internal conductor, wherein the ferrite magnetic layer is made of the ferrite sintered body according to claim 1. A composite laminated part characterized by the above-mentioned. 5. A magnetic core comprising the ferrite sintered body according to claim 1.