JP2007302493A - NiCuZn FERRITE AND ELECTRONIC COMPONENT USING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an NiCuZn ferrite which can be highly densely sintered while it can retain its fine particle diameter upon a temperature change and consequently has a reduced fluctuation in inductance characteristics upon a firing temperature change. <P>SOLUTION: The NiCuZn ferrite comprises as principal components 47.6-49.8 mol% (in terms of Fe<SB>2</SB>O<SB>3</SB>) iron oxides, 8.1-11.5 mol% (in terms of CuO) copper oxides, 1.0-29.0 mol% (in terms of ZnO) zinc oxides, and the balance (mol% in terms of NiO) of nickel oxides and comprises 0.1-0.4 wt.% (in terms of Bi<SB>2</SB>O<SB>3</SB>), based on the principal components, bismuth oxides. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a NiCuZn-based ferrite and an electronic component using the same, and more particularly to a NiCuZn-based ferrite used as a material for a multilayer electronic component and an electronic component manufactured using the same.

  Conventionally, ferrite as an oxide magnetic material containing Ni, Cu, Zn, etc. has excellent magnetic properties. For example, as a core (magnetic core) material of various electronic components or a multilayer chip inductor It is used as a material for inductor parts.

  When manufacturing an electronic component including a coil conductor such as a multilayer chip inductor, if the manufacturing conditions vary, for example, the firing temperature varies, the characteristics of the obtained ferrite will change.

  The tighter the production conditions, the higher the product quality guarantee percentage. However, it is extremely difficult to strictly manage a high firing temperature of about 800 to 1200 ° C. within an error range of about ± 3 ° C., and even if it can be managed, a very high cost is required.

  Therefore, it is desired to propose a NiCuZn-based ferrite in which the change in characteristics is extremely small with respect to fluctuations in manufacturing conditions such as the firing temperature and manufacturing management is easy.

  More specifically, there is a demand for a NiCuZn-based ferrite that can be sintered at a high density while maintaining a fine particle diameter with respect to a temperature change, and as a result, has a small variation in inductance characteristics with respect to a change in firing temperature. Has been.

  The following patent documents are listed as prior art that is considered to be related to the present invention.

Japanese Patent Application Laid-Open No. 2001-76929 discloses a specific surface area of 10 to 20 m for the purpose of obtaining a multilayer inductor that has a good synthesis reaction during calcining and firing of a magnetic layer and that is less susceptible to defects during plating. ^A NiCuZn ferrite obtained by adding ² / g Bi ₂ O ₃ to 0.1 wt% or more and less than 0.5 wt% is disclosed. However, the specific examples of the publication do not disclose the composition of the present invention, and NiCuZn ferrite that exhibits the effect that the change in characteristics is extremely small with respect to fluctuations in manufacturing conditions such as the firing temperature is not exist. In addition, the specific surface area is 10-20 m ² / g, which is very fine compared to conventional Bi ₂ O ₃ (5-6 m ² / g), so that scattering occurs during weighing, Bi ₂ O ₃ raw material Since the production method is a gas phase method, the cost of raw materials may increase, which is not preferable. In contrast, in the present invention in addition also 0.1 to 0.4% by weight while using Bi ₂ O ₃ having a conventional specific surface area, it can be sintered at a sintering temperature of from 890 to 910 ° C..

Japanese Patent Laid-Open No. 2003-243220 discloses Bi ₂ O ₃ for the purpose of obtaining a highly reliable multilayer inductor component in which a decrease in insulation resistance of a sintered body is suppressed and electrical characteristics are hardly deteriorated. NiCuZn-based ferrites that may be included are disclosed. However, in this case as well, as in the above-mentioned Japanese Patent Application Laid-Open No. 2001-76929, the specific example has a low sinterability because the amount of Cu is 6 mol%, and has characteristics against fluctuations in manufacturing conditions such as the firing temperature. There is no NiCuZn-based ferrite that exhibits the effect that the change in the size is extremely small. Furthermore, Bi ₂ O ₃ (mol%): 0.01 and 0.2 are 0.04 and 0.8% by weight in terms of weight, and the particle diameter cannot be controlled at 0.04% by weight. At 0.8% by weight, many abnormally grown particles are generated.

Japanese Patent No. 3201529 proposes a NiCuZn-based ferrite containing Bi ₂ O ₃ for the purpose of providing a ferrite material having excellent impact resistance and excellent strength and electromagnetic characteristics. . However, it is expected that the firing temperature is 1100 ° C. and the ferrite particles are very large. Again, NiCuZn exhibits the effect that the characteristic change is extremely small with respect to fluctuations in manufacturing conditions such as the firing temperature. There is no ferrite. Further, since the firing temperature is as high as 1100 ° C., it is not preferable as a ferrite material for a multilayer type in which a ferrite using a coil conductor such as Ag and Ag—Pd and the coil conductor are simultaneously fired.

JP 2001-76929 A JP 2003-243220 A Japanese Patent No. 3201529

  Under such circumstances, the present invention has been invented, and the object thereof is to sinter at a high density while maintaining a fine particle diameter with respect to temperature changes, as described above. As a result, an object of the present invention is to provide a NiCuZn-based ferrite having a small variation in inductance characteristics with respect to a change in firing temperature.

In order to solve such problems, the present invention is based on iron oxide as a main component in an amount of 47.6 to 49.8 mol% in terms of Fe ₂ O ₃ and copper oxide in an amount of 8.1 to 11.5 mol in terms of CuO. %, Zinc oxide is 1.00 to 29.0 mol% in terms of ZnO, and nickel oxide is the remaining mol% in terms of NiO. Bi ₂ O ₃ 0.1 to 0.4 configured such that it is contained by weight% in terms of.

  Moreover, as a preferable aspect of the NiCuZn-based ferrite of the present invention, the sintered body has an average crystal grain size of 0.6 to 1.3 μm.

Further, the present invention is an electronic component comprising a NiCuZn-based ferrite, the ferrite is 47.6 to 49.8 mol% of iron oxide calculated as Fe ₂ O ₃ as a main component, copper oxide CuO 8.1 to 11.5 mol% in terms of conversion, zinc oxide in the range of 1.00 to 29.0 mol% in terms of ZnO, and nickel oxide in the remaining mol% in terms of NiO. Bi ₂ O ₃ 0.1 to 0.4 configured such that it is contained by weight% in terms of.

  Moreover, as a preferable aspect of the electronic component of the present invention, the electronic component is configured as a multilayer inductor or an LC composite component including a coil conductor and a core portion made of the ferrite.

  Moreover, as a preferable aspect of the electronic component of the present invention, the ferrite is configured such that the average crystal grain size is 0.6 to 1.3 μm.

In the NiCuZn ferrite of the present invention, iron oxide as a main component is 47.6 to 49.8 mol% in terms of Fe ₂ O ₃ , copper oxide is 8.1 to 11.5 mol% in terms of CuO, and zinc oxide is ZnO. 1.0 to 29.0 mol% in terms of conversion, nickel oxide is included in the remaining mol% in terms of NiO, and bismuth oxide is 0.1 to 0.4 wt in terms of Bi ₂ O _{3 with} respect to the main component. %, It can be sintered at a high density while maintaining a fine particle diameter with respect to the temperature change, and as a result, the characteristic variation of the inductance with respect to the change in the firing temperature is small. NiCuZn ferrite is formed.

  Hereinafter, the ferrite (oxide magnetic material) of the present invention will be described in detail.

The ferrite of the present invention is a NiCuZn-based ferrite, and the substantial main component thereof is iron oxide of 47.6 to 49.8 mol% in terms of Fe ₂ O ₃ (particularly preferably, 47.7 to 49.49). 3 mol%), copper oxide is 8.1 to 11.5 mol% in terms of CuO (particularly preferably 8.1 to 10.5 mol%), and zinc oxide is 1.0 to 29.0 mol in terms of ZnO. % (Particularly preferably 10.0 to 27.0 mol%), and nickel oxide is contained in the remaining mol% in terms of NiO.
Furthermore, in the ferrite of the present invention, the bismuth oxide as a subcomponent is 0.1 to 0.4% by weight in terms of Bi ₂ O ₃ (particularly preferably, 0.14 to 0.8%) with respect to such a main component. 37% by weight).

In the composition range of the main component, when the content of iron oxide (Fe ₂ O ₃ ) is less than 47.6 mol%, the sinterability is reduced, and the effect of controlling the crystal particle diameter with respect to the firing temperature is reduced. This is not preferable because there is a tendency that the rate of change of μ with respect to the firing temperature increases. On the other hand, when the content of iron oxide (Fe ₂ O ₃ ) exceeds 49.8 mol%, there arises a disadvantage that the sinterability is significantly deteriorated.

  Further, in the composition range of the main component, when the content of copper oxide (CuO) is less than 8.1 mol%, the sinterability is deteriorated, and the effect of controlling the crystal particle diameter with respect to the firing temperature is reduced, and firing is performed. However, when the content of copper oxide (CuO) exceeds 11.5 mol%, the dissociation of CuO in the ferrite is likely to occur and the specific resistance is increased. When the chip inductor is used, there is a tendency that the plating elongation from the external terminal easily occurs. In addition, abnormally grown crystal grains are likely to be generated, and there is a tendency that the rate of change of μ with respect to the firing temperature tends to increase.

  Furthermore, when the content of zinc oxide (ZnO) is less than 1.0 mol% in the composition range of the main component, there is a tendency that inconvenience that the sinterability deteriorates. On the other hand, if the content of zinc oxide (ZnO) exceeds 29.0 mol%, abnormally grown crystal grains are liable to be produced, and there is a tendency that the rate of change of μ with respect to the firing temperature tends to increase. . In addition, Tc (Curie temperature) is 140 ° C. or less, and there is a concern that the reliability of the components may be inconvenient.

Further, in the composition range of the subcomponents contained with respect to the main component, if the content of bismuth oxide (Bi ₂ O ₃ ) is less than 0.1% by weight, the control of the crystal particle size becomes insufficient. There is a tendency that a change in inductance with respect to the firing temperature cannot be controlled. On the other hand, if the content of bismuth oxide (Bi ₂ O ₃ ) exceeds 0.4% by weight, abnormally grown crystals are produced, and there is a tendency that the direct current superposition characteristics are deteriorated.

In the production process of the above NiCuZn-based ferrite, the specific surface area of the ferrite material after grinding 6.5~9.0 (m ² / g), particularly preferably, from 7.2 to 8.4 (m ² / g) is desirable.

If the specific surface area of the ferrite material after pulverization is less than 6.5 (m ² / g), the rate of change with respect to the firing temperature of μ cannot be suppressed. On the other hand, if the specific surface area exceeds 9.0 (m ² / g), not only the pulverization cost is required, but also the coating becomes difficult.

  For example, the ferrite of the present invention is molded into a core material having a predetermined shape, and after necessary windings are wound, it is resin-molded (resin-coated) and used as a fixed inductor, a chip inductor, or the like. These are used as various electronic devices such as mobile communication devices such as televisions, video recorders, mobile phones and automobile phones. The shape of the core is not particularly limited, and for example, a drum core having an outer diameter and a length of 2 mm or less can be exemplified.

  Examples of the resin used as the mold material (coating material) include thermoplastic and thermosetting resins. More specifically, polyolefin, polyester, polyamide, polycarbonate, polyurethane, phenol resin, urea resin, epoxy resin and the like can be exemplified. As a specific means for molding the molding material, dipping, coating, spraying and the like can be used. Furthermore, injection molding, casting molding, or the like may be used.

  Exemplifying the configuration of a chip inductor (electronic component) using the ferrite of the present invention, the chip inductor, for example, a core formed into a cylindrical body shape having large diameter ridges at both ends using the ferrite of the present invention, Windings wound around the core of the core, terminal electrodes arranged at both ends of the core for connecting the end of the winding and an external electric circuit and fixing the core in the resin, and these And a molding resin formed so as to cover the outside.

  The ferrite of the present invention is a multilayer electronic component formed by laminating and firing a magnetic sheet or dielectric sheet subjected to predetermined processing, that is, a multilayer inductor or a multilayer LC composite component. It can also be a core material. In a multilayer inductor, a plurality of ferrite composition sheets on which an inner conductor for forming a coil-shaped portion is formed may be prepared, and these may be laminated and fired.

  Next, an example of the method for producing a ferrite of the present invention will be described.

  First, a predetermined amount of a predetermined raw material is blended and prepared so that the main component composition and subcomponent (additive) composition after firing are within the predetermined range of the present invention.

Next, the raw material prepared in this way is wet-mixed using a ball mill or the like. This is dried and then calcined. The calcination is performed in an oxidizing atmosphere, for example, in the air. The calcining temperature is preferably 500 to 900 ° C., and the calcining time is preferably 1 to 20 hours. Next, the obtained calcined product is pulverized to a predetermined size (specific surface area of 6.5 to 9.0 (m ² / g)) by a ball mill or the like. In the ferrite of the present invention, it is desirable to add and mix the raw materials of the subcomponents during the pulverization (or after pulverization).

  After calcining the calcined product, an appropriate amount of an appropriate binder such as polyvinyl alcohol is added to form the desired shape.

  Next, the molded body is fired. Firing is performed in an oxidizing atmosphere, usually in air. The firing temperature is about 890, 900, and 910 ° C., and the firing temperature is about 2 hours.

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

Each raw material is blended in a predetermined amount such that Fe ₂ O ₃ , NiO, CuO, and ZnO as the main components in the composition have the composition ratios shown in Table 1 below, and then wet mixed in a steel ball mill for about 20 hours. did.

Further, these mixed powders were dried and then calcined at a predetermined temperature in the air to obtain calcined powders. Bi ₂ O ₃ was added to the calcined powder as an auxiliary component so as to have the composition ratio shown in Table 1 below, and pulverized with a steel ball mill for 80 hours to obtain a pulverized powder.

  After the polyvinyl alcohol solution was added to and mixed with the pulverized powder (ferrite powder) thus obtained, granulated powder was obtained using a spray dryer.

The granules thus obtained were molded into a toroidal shape having an outer diameter of 13 mm, an inner diameter of 6 mm, and a height of 3 mm so that the molding density was 3.10 Mg / m ³ .

  Toroidal core samples produced at different firing temperatures were obtained by firing the molded body thus molded in air at three firing temperatures, that is, 890 ° C., 900 ° C., and 910 ° C. for 2 hours. Obtained.

For each of these samples, (1) the sintered density d _f , (2) the firing temperature dependence of the initial permeability at 100 kHz, and (3) the ferrite particle diameter (average particle diameter) were determined.
In addition, the measurement of said (1)-(3) was performed in the following ways.

(1) Sintering density The density (d _f : unit is Mg / m ³ ) of the sintered body was calculated based on the numerical value obtained using the Archimedes method.

(2) Calcination temperature dependence of initial permeability μi at 100 kHz For each sample manufactured at each calcination temperature of 890 ° C., 900 ° C., and 910 ° C., after winding the wire around the toroidal core sample 20 times, Inductance values and the like were measured, and initial magnetic permeability μi ₈₉₀ , μi ₉₀₀ , and μi _{910 at} 100 kHz and 25 ° C. were obtained (the subscript indicates the firing temperature).

Using these measured values, Δμi _900-10 and Δμi _{900 + 10} defined by the following _formulas were obtained, respectively. The value of Δμi _900-10 shows the variation value of the initial permeability when the firing temperature varies from 900 ° C. to −10 ° C. The value of Δμi _{900 + 10} varies the firing temperature from 900 ° C. to + 10 ° C. The fluctuation value of the initial permeability in the case is shown. A sample having a firing temperature of 900 ° C. is the standard.

Δμi _{900 −10} = (μi ₈₉₀ −μi ₉₀₀ ) / μi ₉₀₀
Δμi _{900 + 10} = (μi ₉₁₀ −μi ₉₀₀ ) / μi ₉₀₀

(3) Ferrite particle size (average particle size)
The following measurements were performed for a range of 100 μm ² or more of the produced sintered body.

  First, the cross-sectional area of each crystal particle was determined by image analysis using a method of converting the number of pixels of the crystal particle into an area. Next, the length of the diameter of a circle having the same cross-sectional area as the calculated cross-sectional area is obtained, and the value calculated by multiplying the value of this diameter by π / 2 is the particle diameter of the crystal particles, The average (crystal) particle diameter was obtained by calculating the average. That is, the average particle diameter was calculated by approximating the cross-sectional area of each particle to a circle.

  The results are shown in Table 1 below.

Note that in the data in Table 1, the sintered density d _f is 5.1 (Mg / m ³⁾ or more, Derutamyuai _900-10, the absolute value within _10%, Δμi _{900 +} 10 that the absolute value within 10% The average ferrite particle diameter (average crystal particle diameter) is a target value of 0.6 to 1.3 μm.

  Note that the particle size in the chip inductor was equivalent to the particle size of 890 ° C. firing.

The effects of the present invention are clear from the above results. That, NiCuZn ferrite of the present invention, from 47.6 to 49.8 mol% iron oxide in terms of Fe ₂ O ₃ as a main component, 8.1 to 11.5 mol% of copper oxide in terms of CuO, zinc oxide There 1.0 to 29.0 mol% in terms of ZnO, nickel oxide and remaining mol% in terms of NiO, with respect to the main component, bismuth oxide calculated as Bi ₂ O ₃ from 0.1 to 0. Since it is configured to contain 4% by weight, it can be sintered at a high density while maintaining a fine particle diameter with respect to temperature change, and as a result, the characteristic variation of inductance with respect to change in firing temperature Can be formed.

Claims (5)

As main components, iron oxide is 47.6 to 49.8 mol% in terms of Fe ₂ O ₃ , copper oxide is 8.1 to 11.5 mol% in terms of CuO, and zinc oxide is 1.00 to 29.9 in terms of ZnO. NiCuZn-based ferrite composed of 0 mol% and nickel oxide remaining in mol% in terms of NiO,
A NiCuZn-based ferrite comprising 0.1 to 0.4 wt% of bismuth oxide in terms of Bi ₂ O _{3 with} respect to the main component.   The NiCuZn ferrite according to claim 1, wherein the sintered body has an average crystal grain size of 0.6 to 1.3 μm. An electronic component comprising NiCuZn-based ferrite,
As for the ferrite, iron oxide as a main component is 47.6 to 49.8 mol% in terms of Fe ₂ O ₃ , copper oxide is 8.1 to 11.5 mol% in terms of CuO, and zinc oxide is 1. in terms of ZnO. 00 to 29.0 mol%, nickel oxide is contained in the remaining mol% in terms of NiO,
An electronic component comprising 0.1 to 0.4% by weight of bismuth oxide in terms of Bi ₂ O _{3 with} respect to the main component.   The electronic component according to claim 3, wherein the electronic component is a multilayer inductor or an LC composite component including a coil conductor and a core portion made of the ferrite. The electronic component according to claim 3 or 4, wherein the ferrite has an average crystal grain size of 0.6 to 1.3 µm.