JP2003257725A - Oxide magnetic material, its manufacturing method, method of forming core, magnetic component, and coil component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide magnetic material from which a high-density molded body for magnetic component that can be suppressed in deformation due to a small density difference in a sintered compact, and is excellent in dimensional accuracy and magnetic characteristic can be obtained; a method of manufacturing the magnetic material; a method of forming core, a magnetic component, and a coil component using the magnetic material. <P>SOLUTION: After a magnetic oxide powder which becomes the oxide magnetic material is weighed, blended, dried, granulated, and calcined, the powder is water-ground. Thereafter, the magnetic oxide powder is made finer in size by dry-grinding the powder. <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 an oxide magnetic material and a method for producing the same, a method for molding a core using the oxide magnetic material, a magnetic component and a coil component, and more particularly to a drum type core shape. The present invention relates to a magnetic component suitable for a complicated shape.

[0002]

2. Description of the Related Art Generally, magnetic oxide powders such as Ni-Zn ferrites are subjected to the steps of mixing of material oxides, calcination, pulverization, granulation, and molding, and then under appropriately controlled high temperature. It is manufactured by firing at.

[0003] Of the above-mentioned steps, the crushing is generally wet crushing, but when molding the powder material after the wet crushing, it is generally difficult to increase the density of the compact. For this reason, if the density of the molded body is increased by increasing the molding pressure,
It is known that deformation and cracks occur after firing due to cracks during molding and uneven density inside the molded body.

Further, when a core for a coil component having a complicated shape such as the drum core 1 shown in FIG. 1 (A) is formed by the lower die 2 and the upper die 3 shown in FIG. 1 (B), a core portion is formed. When excessive pressure is applied for the purpose of preventing the lowering of the density of the collars 1b at both ends of the la, the stress is concentrated only on the core 1a, and the molds 2 and 3 are often damaged. ing. In particular, in FIG. 1 (A), the diameter (in the case where the core 1 of the core 1 has a cylindrical shape) or the width (when the core 1 of the core 1 has a prismatic shape) in the pressing direction of the core 1a. ) A is collar part 1
If the diameter of b in the pressing direction (when the collar is cylindrical) or the width (when the collar is polygonal) is less than 60% of b, as shown in FIG. When pressure is applied in the direction perpendicular to the winding axis direction of the core portion 1a, a density difference occurs in which the winding core portion 1a is relatively dense and the collar portion 1b is relatively sparse, and the above-described cracking, deformation, and gold It is known that mold breakage occurs.

As a means for solving these problems, as described in Japanese Patent Laid-Open No. 9-306774, the diameter or width of the core portion 1a is obtained by cutting the intermediate portion of a molded body integrally molded into a columnar shape or a prismatic shape. There is a case where a method of processing 60% or less of the collar portion 1b is used. However, in the case of this cutting, the productivity is poor, and the productivity including the dimensional accuracy lowers particularly as the shape becomes smaller with a length of, for example, about 1 mm.

In addition to this cutting method, cold isostatic pressing (CIP), which applies a molding pressure relatively uniformly from all directions during molding, is known, but in the case of making a relatively large molded body, Although the effect is large, the effect is insufficient for a complicated molded body such as a drum core, and the ability to mold at one time is limited. Therefore, this method is not suitable for mass production.

Further, in recent years, various electronic devices have been rapidly reduced in size and weight, and in order to meet the demand, demands for miniaturization and high performance of electronic parts used in electric circuits of these electronic devices are also rapidly increased. Is coming. For this reason, in order to respond to further miniaturization of parts, it is necessary to develop a molding method that enables accurate molding in large quantities in a limited time, and of course, efforts from fields related to powder materials. Has become essential.

In order to meet these demands, Japanese Patent Laid-Open No. 5-4
According to Japanese Patent No. 3248, the powder material is dry pulverized and then wet pulverized to change the agglomeration state of the particles so that the compacted body has a compressed density of 2.6 g / cm ^{3 to} 3.
A density control method for continuously controlling in the range of 2 g / cm ³ is described.

[0009]

As described above, if the oxide magnetic material after calcination is pulverized only by wet pulverization, the powder cannot be aggregated and the compressed density cannot be increased. In addition, coarse particles tend to remain.

On the other hand, only by dry pulverization, although coarse particles can be made finer and powder can be aggregated, there is a problem that the density of the sintered body is not increased and desired electromagnetic characteristics cannot be obtained. Further, there is a problem that impurities are mixed from the inner wall of the crusher or the media before the crushing to the target average particle size.

Therefore, it is conceivable that the powder material is dry-milled and then wet-milled as described in JP-A-5-43248. According to this method, the agglomeration produced by the dry milling is performed. It has a tendency to loosen slightly and the compression density further decreases. As a result, it is difficult to obtain a compact having a high compression density of 3.2 g / cm ³ or more, and thus it is difficult to obtain a core having a high compact strength. Further, it is difficult to suppress defects such as density difference and deformation inside the sintered body, and there is a problem that a magnetic component excellent in dimensional accuracy and electromagnetic characteristics cannot be stably manufactured.

In view of the problems of the prior art as described above, the present invention has a high density as a molded body of a magnetic component, has a small density difference inside the sintered body, can suppress deformation, and has dimensional accuracy,
It is an object of the present invention to provide an oxide magnetic material that can obtain a material having excellent electromagnetic characteristics and a method for producing the same.
Another object of the present invention is to provide a method for molding a core using the above oxide magnetic material, and a magnetic component and a coil component.

[0013]

Means for Solving the Problems The method for producing an oxide magnetic material according to the present invention comprises: measuring and blending a plurality of types of oxides which are materials for a magnetic oxide, calcining the mixture, and calcining the magnetic oxide. It is characterized in that the powder is subjected to a wet pulverization treatment and then subjected to a dry pulverization treatment to make the magnetic oxide powder fine.

As described above, by performing the dry pulverization after the wet pulverization, aggregation is more likely to occur and the compression density can be increased as compared with the case of the simple wet pulverization, and moreover, the case of the simple dry pulverization. Pretreatment by wet pulverization makes it possible to increase the density of the sintered body and improve the electromagnetic characteristics.

Further, by performing the dry pulverization after the wet pulverization, the time of the dry pulverization can be shortened, so that the mixing of impurities from the inner wall of the pulverizer and the media can be reduced, and the inside of the core (in the case of a drum core, In addition to the reduction of the density difference between the core and the collar, the electromagnetic characteristics of the magnetic component can be improved.

More specifically, coarse particles in the magnetic oxide powder, which could not be sufficiently crushed by the wet crushing process, are crushed in a short time so that the average particle size is 0.4 to 1.8 μm, more preferably 0. Oxide magnetic material powder having a sharp particle size distribution of 6 to 1.2 μm can be obtained.

Further, while treating the specific surface area to 2.4 g / cm ³ or more, the oxide magnetic material powder is aggregated to control the compression density of the molded body to 3.2 g / cm ³ or more even under low pressure molding. In this way, a core having a complicated shape can be integrally molded without grinding or the like.

In the present invention, a wet ball mill, an attritor or the like can be used as a pulverizer used for wet pulverization, and a dry ball mill, a vibration mill or the like can be used as a pulverizer used for dry pulverization.

As a method for producing an oxide magnetic material using the production method of the present invention, a magnetic oxide is applicable to a Mn-Zn type ferrite, but Ni-Zn which has a particularly high electric resistance and can be directly wound on a coil. It can be suitably applied as a method for producing a system ferrite (claim 2).

Further, when the production method according to the present invention is carried out, after the wet pulverization and the dry pulverization, the magnetic oxide powder is slurried, and then the granules are dried and molded to obtain a particle size of 0. Molded product density at 1 MPa is 3.2 g
It is possible to carry out the pulverization treatment so as to obtain a molded product having a density of / cm ³ or more (claim 3).

Further, after the magnetic oxide powder that has been subjected to the pulverization treatment by the manufacturing method of the present invention is slurried,
When press-molding into a core shape through granulation and drying steps, the minimum width of the core in the pressurizing direction is set to 65% or less of the maximum width in the pressurizing direction (Claim 4). It can be carried out with a high yield as a united product.

Further, after the magnetic oxide powder that has been subjected to the pulverization treatment by the above-mentioned manufacturing method of the present invention is slurried,
When press-molding into a drum-shaped core shape in the direction perpendicular to the core axis direction through granulation and drying steps, the diameter or width of the core in the pressurizing direction can be adjusted by pressing the collar section. By making the diameter or width in the direction 60% or less of the width (Claim 5),
It can be carried out with a high yield as a sintered product.

Further, after the magnetic oxide powder which has been pulverized by the above-mentioned manufacturing method of the present invention is slurried, it is granulated,
Amount of change in molding pressure ΔP (M
Amount of change in density of molded body with respect to Pa) Δd (g / cm ³ )
In the molding pressure range of 0.05 MPa to 0.3 MPa, a ratio Δd / ΔP of Δd / ΔP ≦ 1.6 can be obtained, and an oxide magnetic material (claim 6) having such characteristics can be obtained. It is preferable to have a high compaction density with a low molding pressure (that is, to reduce cracks and deformation in the sintered product) and to obtain a uniform density distribution.

Further, the amount of change Δd in the compact density of the magnetic oxide powder that has been pulverized by the above-described manufacturing method of the present invention.
Change amount ΔD of density after sintering with respect to (g / cm ³ ).
The ratio ΔD / Δd of (g / cm ³ ) is ΔD / Δd ≦ 0.13.
It is possible to obtain an oxide magnetic material (claim 7) that is
Moreover, it is preferable to have such characteristics in order to obtain a high sintered compact density at a low molding pressure (that is, to reduce cracking and deformation in the sintered compact product).

Further, by using a magnetic component (claim 8) formed and sintered from the magnetic oxide powder that has been pulverized by the above-mentioned manufacturing method of the present invention, the density difference inside the sintered body can be reduced. It is possible to obtain a magnetic component which is small and has a small yield with a good yield and excellent electromagnetic characteristics.

Further, by obtaining the coil component having the magnetic component as the core by the manufacturing method of the present invention (claim 9), the coil component having excellent electromagnetic characteristics can be obtained.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an oxide magnetic material of the present invention is suitable for obtaining materials for inductors, transformers, antennas, television cathode ray tubes, and other parts that require magnetism. A magnetic part having a complicated shape such as a drum core as shown in (A), that is, a diameter or width a or b in the pressing direction of the molded body is significantly different in the moving direction of the mold during molding is obtained. In this case, it is suitable as an oxide magnetic material.

FIG. 2 is a block diagram showing an embodiment of a method for producing an oxide magnetic material according to the present invention. As shown in FIG. 2, in the present embodiment, individual oxide powders are weighed so that ferrite having predetermined characteristics is obtained,
Wet mixing is performed by adding water (step a). Next, dry granulation is performed using a spray dryer or the like (step b). Next, this powder is calcined (step c).

Next, water is added to this sintered body and wet pulverization is performed by a wet ball mill or the like (step d). The crushed product is dried (step e). Then, the wet-milled and dried product is dry-milled by a dry vibrating ball mill or the like (step f). Next, an oxide magnetic material powder is obtained by adding an appropriate amount of a dispersant, a binder and the like (step g) and performing dry granulation using a spray dryer or the like (step h).

[0030]

EXAMPLES (Comparative Example 1) - Wet grinding _{Fe 2 O 3, ZnO, NiO} , and after wet mixing of the oxide material consisting of CuO in a predetermined molar ratio, and then calcined at 900 ° C.. The obtained oxide composition was Fe ₂ O ₃ : Zn.
O: NiO: CuO = 66.3: 19.6: 9.3:
It was 4.8 (wt%). The specific surface area of the material after the calcination is 1.2 m ² / g, and the compression density is 2.40 g / c.
It was m ³ . Next, this oxide was wet-milled.
This wet pulverization was carried out for 20 hours by a wet ball mill with 1500 g of balls as 1000 g of oxide powder.

Next, after adding an appropriate amount of a binder and a dispersant to the pulverized oxide, dry granulation was performed using a spray dryer.

(Comparative Example 2) -Dry pulverization The same calcined material as in Comparative Example 1 was dry pulverized without wet pulverization. Dry pulverization is performed by a dry vibrating ball mill, and 60 g of oxide powder is added to 4000 g of balls.
0 g was added and the operation was performed for 90 minutes. Next, after the dry pulverized product was slurried in a wet process, an appropriate amount of a binder, a dispersant and the like were added, and dry granulation was performed using a spray dryer.

Example 1 Wet Grinding + Dry Grinding After wet grinding as in Comparative Example 1, this was further dry ground. Dry pulverization was performed with a dry vibration type ball mill, and 6 parts of oxide powder was added to 4000 g of balls.
00g was added and it performed for 60 minutes. Next, after the dry pulverized product was slurried in a wet process, an appropriate amount of a binder, a dispersant and the like were added, and dry granulation was performed using a spray dryer.

Example 2 Wet Grinding + Dry Grinding After wet grinding as in Comparative Example 1, this was dry ground. Dry pulverization is performed with a dry vibration type ball mill, and 600 g of oxide powder is added to 8000 g of balls.
In addition, it went for 60 minutes. Next, after the dry pulverized product was slurried in a wet process, an appropriate amount of a binder, a dispersant and the like were added, and dry granulation was performed using a spray dryer.

(Measurement of Properties, etc.) The particle size distribution of each powder produced as described above, the compression density at various molding pressures, and the change in compression density with respect to changes in molding pressure were measured. Moreover, what was compression-molded in an annular shape using such various powders was fired at 1000 to 1200 ° C. in a firing furnace. Then, the sintered body density, electromagnetic characteristics (initial magnetic permeability μ _i , saturation magnetic flux density B _S ) and the like were obtained. Similarly, the dimensional accuracy, the yield, and the like were obtained with the drum core shape.

[Particle Size Distribution] FIG. 3 shows the particle size distribution in each of the above examples. As shown in FIG. 3, in the case of Comparative Example 1 only by wet pulverization, Comparative Example 2 by dry pulverization or wet pulverization +
The particle size is larger than in Examples 1 and 2 by dry crushing,
Moreover, the particle size distribution is not sharp, and the particle size extends over a wide range.

In the case of Comparative Example 2 and Examples 1 and 2, there is almost no difference in particle size and particle size distribution, and it is possible to make the particle size smaller and uniform in particle size as compared with the case of only wet pulverization. I understand. That is, in the case of Examples 1 and 2, although the dry pulverization time was shortened (that is, the mixing of impurities from the inner wall of the pulverizer and the media was reduced), the dry pulverization time was almost the same as Comparative Example 2. A particle size distribution can be obtained.

[Compressed Density] No. 1 of Table 1 and FIG. 4 show the compressed densities of the powders obtained in the above-mentioned respective examples when molded under various molding pressures. As shown in No. 1 of Table 1, as compared with Comparative Example 1 only by wet grinding, Comparative Example 2 only by dry grinding and Example 1 by wet grinding + dry grinding,
In the case of 2, the high compression density can be obtained at 0.05 MPa to 0.3 MPa.

[0039]

[Table 1]

[Δd / ΔP] In Table 2, No. 2, the compression density (g / c) with respect to the variation ΔP of the molding pressure (MPa) is shown.
m ³ ), the ratio Δd / ΔP of the change amount Δd of the change amount of the molding pressure is 0.05 to 0.3, 0.05 to 0.1, 0.05 to
It shows about each range of 0.2, 0.2-0.3, 0.1-0.3 (MPa).

As can be seen from No. 2 in Table 2, as compared with Comparative Example 1 by wet pulverization only, in the case of Comparative Example 2 by dry pulverization only and Examples 1 and 2 by wet pulverization + dry pulverization, the ratio Δd / It was found that ΔP becomes small and a high compression density can be obtained at a low pressure. In Examples 1 and 2 and Comparative Example 2, the range of change in molding pressure is 0.05 to
A value of Δd / ΔP = 1.6 or less is obtained in the range of 0.3 MPa.

[Sintered Body Density] FIG. 5 shows the sintered body densities of the compacts of Examples 1 and 2 and Comparative Examples 1 and 2. In the case of Examples 1 and 2, the compact density is 3.2 to 3.6 g /
In the range of cm ^3, a higher sintered body density than that of Comparative Examples 1 and 2 was obtained. It is also in the scope of the green density, the ratio [Delta] D / [Delta] d of the variation [Delta] D of the sintered body density with respect to the change amount [Delta] d of the green density ^{(g / cm 3) (g} / cm 3) is the Examples 1 and 2 In this case, the value was 0.13 or less, which was smaller than 0.25 in Comparative Example 1, and it was confirmed that the sintered body density was high even when the compact density was low.

[Yield and Electromagnetic Characteristics] In each of the above examples
The obtained powder is used for molding at a molding pressure of 0.1 MPa.
Die damage, effective molding number, yield and electromagnetic characteristics
(Initial permeability μ_i, Saturation magnetic flux density B _S) And sintered body density
Table 2 shows the obtained results. In Comparative Example 1, 5,000 pieces
It was worn out and became unusable. On the other hand, Comparative Example 2
In the case of Examples 1 and 2, molding of 200,000 pieces
However, the mold did not wear so much that it became unusable.

Considering mass production, a yield of 80% or more is usually desirable. In the case of Comparative Example 2, when 200,000 pieces were molded, the dimensional accuracy was poor due to deformation and the like, and 60 to 70%.
The yield of 1 was obtained, but in the case of Example 1, the yield of 85% or more was obtained, and in the case of Example 2, the yield of 90% or more was obtained.

Further, as shown in Table 2, the initial magnetic permeability μ _i ,
Regarding the saturation density B _S and the sintered body density d, Comparative Examples 1 and 2
In comparison with the above, all of the cases according to Examples 1 and 2 were able to give excellent numerical values. In the case of Examples 1 and 2,
This is because the difference in density between the constituent parts (core and flange) of the sintered body can be reduced.

[0046]

[Table 2]

The relationship between the core / collar ratio (diameter or width of the core / diameter or width of the collar) and the number of effective moldings (the number of cores that can be molded with one set of dies) when molded into a drum core shape It shows in Table 3. As shown in Table 3, regarding the core collar ratio and the effective molding number, in the case of Examples 1 and 2 and Comparative Example 2, the number of effective moldings is 200,000 or more up to the core collar ratio of 45%. , The practically sufficient number of moldings has been obtained. Further, when the core-collar ratio is 35%, 100 is obtained in Example 1 and Comparative Example 2,
Although the number of effective moldings is 000, the number of moldings in Example 2 is 150,000, which is relatively small, a practical number of moldings is obtained. In Comparative Example 1, the number of moldings that can be practically used is obtained up to the core-collar ratio of 70%, but the mold breakage occurs at the boundary of 65%, and the effective number of moldings tends to be drastically reduced. This is because an excessive pressure is applied to the core at the time of molding, so that the mold cannot withstand the load and is damaged.

[0048]

[Table 3]

[0049]

EFFECTS OF THE INVENTION According to the present invention, since wet pulverization is performed before dry pulverization, a magnetic oxide powder having a small particle size can be obtained.
It is possible to obtain a compact having a high compression density with a low compacting pressure, and thus it is possible to obtain a core for a magnetic component and a coil component, which has a high density of the sintered compact and has a small difference in density between constituent parts.

Further, the product yield is improved as compared with the case where the dry crushing treatment is simply performed. Such an improvement in yield can obtain a high compact density with a low compaction pressure, can suppress deformation and cracks, and can suppress the density difference between the constituent parts of the compact to be extremely small.
This is because the amount of impurities mixed is further reduced to improve the electromagnetic characteristics.

After the wet pulverization and the dry pulverization, 0.
By obtaining a compact having a compact density of 3.2 g / cm ³ or more at 1 MPa, it is possible to obtain a magnetic component and a coil component having a high sintered compact density and excellent electromagnetic characteristics.

When the core is pressure-molded, the minimum width of the core in the pressure direction is set to 65% or less of the maximum width, or the diameter of the core in the drum core shape in the pressure direction. Also, even when processing and molding magnetic parts with complicated shapes such as those whose width is 60% or less of the diameter or width of the brim in the pressing direction, the density difference of the constituent parts is small and the yield is improved. It becomes possible to do.

[Brief description of drawings]

FIG. 1A is a side view showing a drum core which is an example of a magnetic component manufactured according to the present invention, and FIG. 1B is a cross-sectional view showing a manufacturing die thereof.

FIG. 2 is a block diagram showing an embodiment of a method for producing an oxide magnetic material according to the present invention.

FIG. 3 is a diagram showing particle size distributions of an oxide magnetic material according to a manufacturing method of the present invention and an oxide magnetic material of a comparative example.

FIG. 4 is a diagram showing a relationship between a molding pressure and a compression density of an oxide magnetic material according to a manufacturing method of the present invention and an oxide magnetic material of a comparative example.

FIG. 5 is a diagram showing the relationship between the compact density and the sintered compact density of the oxide magnetic material according to the manufacturing method of the present invention and the oxide magnetic material of the comparative example.

[Explanation of symbols]

1: Drum core, 1a: Core part, 1b: Collar part, 2: Lower mold, 3: Upper mold

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takuya Ono             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -D-K Co., Ltd. F-term (reference) 5E041 AB01 BD01 HB17 NN02

Claims (9)

[Claims] 1. A plurality of kinds of oxides, which are materials for magnetic oxides, are weighed and mixed, and then calcined, and the calcined magnetic oxide powders are subjected to wet pulverization treatment and then dry pulverization treatment. A method for producing an oxide magnetic material, which comprises miniaturizing a magnetic oxide powder. 2. The magnetic oxide according to claim 1 is Ni-
A method for producing an oxide magnetic material, which is a Zn-based ferrite. 3. A slurry of the pulverized magnetic oxide powder according to claim 1 or 2 is slurried, and then granulated and dried to form a compact, thereby obtaining a compact having a density of 0.1 MPa. A method for producing an oxide magnetic material, which comprises obtaining a molded body of 3.2 g / cm ³ or more. 4. When the magnetic oxide powder that has been crushed according to claim 1 or 2 is slurried and then subjected to granulation and drying steps to form a core shape under pressure, A method for molding a core, wherein the minimum width in the pressure direction is 65% or less of the maximum width in the pressure direction. 5. The magnetic oxide powder which has been crushed according to claim 1 or 2 is slurried, then granulated and dried to form a drum-shaped core in the axial direction of the core. On the other hand, when pressure molding is performed in the vertical direction, the diameter or width of the core portion in the pressure direction is 60% or less of the diameter or width of the collar portion in the pressure direction. Molding method. 6. A change amount ΔP (MP) in molding pressure when the magnetic oxide powder subjected to the pulverization treatment according to claim 1 or 2 is slurried and then granulated and dried.
The ratio Δd / ΔP of the amount of change Δd (g / cm ³ ) of the compact density to a) is characterized in that Δd / ΔP ≦ 1.6 in the molding pressure range of 0.05 MPa to 0.3 MPa. Oxide magnetic material. 7. A change amount Δd (g / g) in the density of a compact of the magnetic oxide powder which has been subjected to the pulverization treatment according to claim 1 or 2.
cm ³ ), the amount of change in density after sintering ΔD (g / c
An oxide magnetic material characterized in that the ratio ΔD / Δd of m ³ ) is ΔD / Δd ≦ 0.13. 8. A magnetic component obtained by molding and sintering the magnetic oxide powder which has been subjected to the crushing treatment according to claim 1 or 2. 9. A coil component comprising the magnetic component according to claim 8 as a core.