JP2016094321A - Ferrite sintered body and noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrite sintered body and a noise filter less in threshing by various processes or heat received repeatedly and small in effects on wiring formation.SOLUTION: The ferrite sintered body contains oxide containing Fe, Ni, Zn and Cu as a main component and at least one of oxide of La and oxide of Pr as accessory component with contents based on total 100 mass% of the main component of total 0.01 mass% to 0.60 mass% of La in terms of LaOand Pr in terms of PrOand average crystal grain diameter of 6 μm or less (excluding 0 μm).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ferrite sintered body and a noise filter in which electrodes are provided inside and outside the ferrite sintered body.

  Ferrite sintered bodies are used for inductors, transformers, ballasts and electromagnets for insulation and transformation purposes, for example, by using the ferrite sintered body as a core and winding the metal wire alone or around this core. In order to prevent an electronic component from being adversely affected by noise generated from an electric circuit incorporated in an electronic device or the like, it is used in a filter for the purpose of noise removal.

Then, as the ferrite material used in the core of such applications, the ratio Ni-Zn ferrite material are known high resistance, for example, Patent Document 1, the main component Fe ₂ O ₃ 44.5~ In a low-loss oxide magnetic material having 49.8 mol%, NiO 10.5 to 25.5 mol%, ZnO 20.0 to 35.0 mol%, and the balance being CuO, La ₂ O ₃ and Ce ₂ O ₃ are used as subcomponents. , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O _3, and Tb ₂ O ₃ , at least one kind is 0 to 5.0 mol% (however, 0 is included) A low-loss oxide magnetic material has been proposed.

JP 2000-124022 A

  In recent years, miniaturization and weight reduction of various electronic devices are rapidly progressing, and in order to cope with this, noise filters have progressed to chip types in which electrodes are provided inside and outside. In forming a chip-type noise filter, generally, from the viewpoint of production efficiency, a plurality of chips are simultaneously formed. First, a thickness of a sintered body made of ferrite using a slicer or the like is used. After slicing to cut out a thin substrate, wiring to be an internal electrode is formed, dicing using a dicer or the like to form a chip, and then laminating to form an external electrode Yes.

  In recent years, demands for further miniaturization and weight reduction have increased, and along with this, wiring miniaturization has progressed. In forming a chip-type noise filter, ceramic particles are formed by slicing or dicing. If this occurs, the wiring cannot be formed or the conduction region becomes narrow, so that the function as a noise filter cannot be exhibited, or as a noise filter. There was a problem that the function of could not be demonstrated over a long period of time.

  In addition, degranulation itself is not preferable in terms of high performance and reliability of various electronic devices, so that not only processing for forming a stacked chip type but also shape formation by press processing that has been performed conventionally. In various processing such as surface processing and surface processing, there is a demand for less degranulation. Furthermore, the use of various electronic devices, that is, the operation of the mounted electronic components, the electronic components generate heat, and the ferrite sintered body also receives this heat. Therefore, there is a demand for less shedding.

  For this reason, this ferrite sintered body is required to have less degranulation due to various processes and repeated heat, and to have a small influence on wiring formation even if degranulation.

  The present invention has been devised to satisfy the above-mentioned requirements. Ferrite sintered bodies that are less affected by various processes and repeated heat and have little influence on wiring formation, and the inside and outside of this ferrite sintered body. An object of the present invention is to provide a noise filter provided with electrodes.

The ferrite sintered body of the present invention includes an oxide containing Fe, Ni, Zn and Cu as a main component, and includes at least one of an oxide of La and an oxide of Pr as a subcomponent, The total content of 100% by mass is 0.01% to 0.60% by mass in terms of La in terms of La ₂ O ₃ and Pr in terms of Pr ₂ O ₃ , and the average crystal grain size is 6 μm or less ( 0 μm is not included).

  The ferrite sintered body of the present invention is less affected by various processes and repeated heat and has little influence on wiring formation.

  The noise filter of the present invention exhibits a function as a noise filter over a long period of time because the ferrite sintered body is less affected by various processing and repeated heat and has little influence on wiring formation. can do.

It is a perspective view which shows an example of the noise filter of this embodiment.

  Hereinafter, the ferrite sintered body and noise filter of the present invention will be described. The ferrite sintered body of the present embodiment uses the ferrite sintered body as a core, and wraps a metal wire around the core alone, or is used for an inductor, a transformer, a ballast, and an electromagnet for insulation and transformation purposes. Or used in a noise filter for the purpose of noise removal or the like.

The ferrite sintered body of the present embodiment includes an oxide containing Fe, Ni, Zn, and Cu as a main component, and includes at least one of an oxide of La and an oxide of Pr as a subcomponent, The content with respect to the total of 100% by mass of the components is 0.01% to 0.60% by mass in terms of La in terms of La ₂ O ₃ and Pr in terms of Pr ₂ O ₃ , and the average crystal grain size is 6 μm. The following (not including 0 μm).

The oxides containing Fe, Ni, Zn and Cu as the main components constitute the ferrite crystal constituting the ferrite sintered body of the present embodiment, and each of Fe, Ni, Zn and Cu is oxidized. The total of the components converted into a product is preferably 98% by mass or more, more preferably 99% by mass or more, out of 100% by mass of all components constituting the ferrite sintered body. In calculating the content of Pr oxide, it is converted to Pr ₂ O ₃ , but it is considered that it exists as Pr ₆ O ₁₁ as an existing form.

And since the ferrite sintered compact of this embodiment which satisfy | fills the structure mentioned above has few degranulation by various processes and the heat | fever which receives repeatedly, and an average crystal grain size is small, even if it degranulates, the influence which it has on wiring formation is small. Is. The reason why the degranulation due to various processes is reduced is that the auxiliary component powder is added and pulverized after calcination, so that the auxiliary component is dispersed around the synthesized calcined powder. This is because the grain growth of the ferrite crystal is suppressed and a compressive stress is applied to each ferrite crystal. Moreover, degranulation due to repeated heat is reduced because La oxide and Pr oxide have a high melting point, and changes due to heat generated by the operation of electronic components mounted on various electronic devices are small. is there. And the average crystal grain size is as small as 6 μm or less (not including 0 μm), as well as the effect of suppressing the grain growth of ferrite crystals by the subcomponents. By grinding to about 2 μm.

  As described in JP-A-2000-124022, the provisional addition of the sub-component powder to the Fe oxide powder, Ni oxide powder, Zn oxide powder, and Cu oxide powder is temporary. When calcined, an oxide compound containing Fe and at least one of La and Pr is produced during calcination, and the effect of suppressing the grain growth of ferrite crystals during the firing process is small, and the average crystal grain size is 6 μm. It will exceed.

In addition, when the content with respect to the total of 100% by mass of the main components is less than 0.01% by mass and more than 0.60% by mass in terms of La in terms of La ₂ O ₃ and Pr in terms of Pr ₂ O ₃ , firing The effect of suppressing the grain growth of ferrite crystals in the process is small.

  Here, a method for measuring the average crystal grain size of the ferrite sintered body will be described. On the obtained photograph, a surface obtained by processing the surface of the ferrite sintered body is used as a measurement surface, and a backscattered electron image is taken at a magnification of, for example, 2000 using a scanning electron microscope (SEM). A straight line crossing method in which 6 straight lines are drawn, the number of crystal grains crossed by the straight line and the total length of each crystal are measured, and the total length of each crystal is divided by the number of each crystal. It can ask for.

And as for the main component composition, Fe is 47.5 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ when the total of components converted to oxides of Fe, Zn, Ni and Cu is 100 mol%. Ni is 12.5 mol% or more and 17.6 mol% or less in terms of NiO, Zn is 27.1 mol% or more and 32.8 mol% or less in terms of ZnO, and Cu is 3.6 mol% or more and 8 mol or less in terms of CuO. % Or less is preferable. The ferrite sintered body of the present embodiment satisfying such a configuration has a magnetic permeability of 450 or higher and a Curie temperature of 140 ° C. or higher.

  The ferrite sintered body of the present embodiment has the same composition as the main component and does not contain any subcomponent, and has the same Curie temperature and lowers the magnetic permeability. The fall of the permeability is smaller than that obtained.

  Here, regarding the magnetic permeability, the sample may be measured under the condition of a frequency of 100 kHz using an LCR meter. As a sample, for example, a ring-shaped sample made of a ferrite sintered body having an outer diameter of 13 mm, an inner diameter of 7 mm, and a thickness of 3 mm is prepared, and 10 coated conductors having a wire diameter of 0.2 mm are provided over the entire circumference of the ring-shaped sample. What is wound may be used. Further, the Curie temperature can be obtained by a bridge circuit method using an LCR meter using the same sample as that at the time of permeability measurement.

For the calculation method of the composition range of the main component, the content of Fe, Ni, Zn, Cu is determined using an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer (ICP) or an X-ray fluorescence analyzer (XRF). determined, respectively _{Fe 2 O 3, NiO, ZnO} , in terms of CuO, calculated the mol value from each of the molecular weight can be confirmed by calculating the occupancy rate for a total of 100 mole%. Further, with respect to the total 100 mass% of the main component, the La _La 2 _{O 3} in terms, a method for calculating the content in which the Pr _Pr 2 _{O 3} in terms of, first, using ICP or XRF, La, the content of Pr Are calculated in terms of La ₂ O ₃ and Pr ₂ O ₃ , respectively, and the content of all the components constituting the ferrite sintered body is obtained. That's fine.

  The subcomponent is preferably an oxide of La. This is because La oxide and Pr oxide have the same effect of suppressing the grain growth of ferrite crystals during the firing process, but Pr oxide is more expensive than La oxide. This is because the particle size of the commercially available Pr oxide is large, and the pulverization time is longer than when the La oxide is used.

  FIG. 1 is a perspective view showing an example of the noise filter of the present embodiment, and the noise filter 10 of the example shown in FIG. 1 includes external electrodes 2 at both ends of a sintered ferrite body 1 and is illustrated. However, the ferrite sintered body 1 is formed by laminating a plurality of thin substrates made of ferrite and includes an internal electrode.

  In general, from the viewpoint of production efficiency, such a chip-type noise filter 10 is formed from a ferrite sintered body using a slicer or the like so that a plurality of substrates can be formed simultaneously. After the slicing process is performed, a wiring to be an internal electrode is formed, a dicing process is performed using a dicer or the like to form a chip, and then the external electrode 2 is formed by laminating.

  Thus, in forming the chip mold, the ferrite sintered body 1 is subjected to slicing and dicing, but the ferrite sintered body 1 is made of the ferrite sintered body of the present embodiment. Since the slicing or dicing process is less likely to cause grain loss and has little influence on wiring formation, the function as a noise filter can be exhibited over a long period of time.

Next, details of an example of the method for producing a ferrite sintered body according to the present embodiment will be described below. The method for producing a ferrite material according to the present embodiment is as follows. First, as starting materials, oxides of Fe, Ni, Zn and Cu, or metals such as carbonates and nitrates that generate oxides of Fe, Ni, Zn and Cn by firing Prepare salt powder. At this time, the average particle diameter is, for example, 0.5 μm or more and 5 μm or less when Fe is iron oxide (Fe ₂ O ₃ ), Zn is zinc oxide (ZnO), and Ni is nickel oxide (NiO), respectively. Is preferred.

  Then, a desired amount of the prepared powder is weighed, pulverized and mixed with a ball mill, a vibration mill, or the like, and then calcined at a temperature of 600 ° C. or higher and 800 ° C. or lower for 2 hours or more to obtain a synthesized calcined body.

In the ferrite sintered body, the main component composition, Fe, Ni, Zn, when the main component total in terms of each oxide of Cu is 100 mole%, Fe is in terms _{of Fe} 2 _{O 3} 47. 5 mol% or more and 50 mol% or less, Ni is 12.5 mol% or more and 17.6 mol% or less in terms of NiO, Zn is 27.1 mol% or more and 32.8 mol% or less in terms of ZnO, and Cu is in terms of CuO It is preferable to weigh so that it becomes 3.6 mol% or more and 8 mol% or less.

Next, at least one of La oxide powder and Pr oxide powder is prepared, and the content of the main components in the ferrite sintered body with respect to 100% by mass in total is La converted to La ₂ O ₃ , and Pr to Pr Weigh so that the total in terms of ₂ O ₃ is 0.01 mass% or more and 0.60 mass% or less, and put into a ball mill, vibration mill, or the like together with the calcined body, and pulverize until the average particle diameter becomes 2 μm or less. Mix. In addition, it takes about 30 hours to pulverize the average particle size to about 1 μm, which increases the possibility of sinterability, prolongation of the production process, and contamination of impurities from balls, mills, etc. In view of this, the pulverization time is preferably less than 36 hours, so the lower limit of the average particle size is about 0.6 μm. Therefore, the lower limit of the average grain size of the ferrite sintered body is about 1.5 μm.

  And after grind | pulverizing until it becomes an average particle diameter of 2 micrometers or less, a predetermined amount of binder is added and it is set as a slurry, A spherical granule is obtained by granulating using a spray granulator (spray dryer).

  Next, this spherical granule is press-molded to obtain a molded body having a predetermined shape. And after performing the binder removal process in the range of 400-800 degreeC in the range of 400-800 degreeC with the obtained molded object, this is hold | maintained at the maximum temperature of 950-1100 degreeC for 2 to 5 hours with a baking furnace. Then, the ferrite sintered body of the present embodiment can be obtained by firing.

  The ferrite sintered body of the present embodiment thus obtained has the ferrite sintered body as a core, and the core alone or as a coil component in which a metal wire is wound around the core, for example, for insulation or transformation. It can be used for inductors, transformers, ballasts and electromagnets, and for noise filters for the purpose of noise removal.

  Moreover, in order to obtain a noise filter as shown in FIG. 1, slice processing is performed by cutting out a thin substrate from a sintered body made of ferrite using a slicer or the like, and then wiring to be an internal electrode is formed. A dicer or the like may be used for dicing to form a chip, and then stacked to form an external electrode.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

  Samples with different subcomponent additions, addition timings, and addition amounts were prepared, the permeability μ and the Curie temperature Tc were measured, and the average crystal grain size was calculated. First, as starting materials, powders of iron oxide, nickel oxide, zinc oxide and copper oxide having an average particle diameter of 1 μm as main components and lanthanum oxide and praseodymium oxide as auxiliary components were prepared.

  And it weighed so that it might become a composition shown in Table 1. In addition, about a main component, it measured so that the composition range when the sum which each converted Fe, Ni, Zn, and Cu into an oxide might be 100 mol% becomes a value shown in Table 1, About subcomponents, It is weighed so that the content with respect to 100% by mass of the main components becomes the value shown in Table 1. Sample No. 2 containing subcomponent powders was also obtained. 11 to 51, sample No. No. 21 uses praseodymium oxide powder, and sample no. No. 22 used lanthanum oxide powder and praseodymium oxide powder, and others used lanthanum oxide powder.

  And sample no. For 1 to 10 and 21 to 51, the auxiliary component was not added, and the weighed main component powder was placed in a ball mill, pulverized and mixed, and then calcined at a temperature of 700 ° C. for 2 hours to synthesize temporary A fired body was obtained. Sample No. About 11-20, after putting the weighed powder of the main component and the weighed powder of the minor component into a ball mill and pulverizing and mixing, calcined at 700 ° C. for 2 hours to synthesize the calcined body. Obtained.

  Next, sample No. For Nos. 1 to 20, the calcined body is referred to as Sample No. As for 21 to 51, the calcined body and the powder of the auxiliary component were put in a ball mill and pulverized and mixed for 36 hours. By this pulverization and mixing, the calcined body became a calcined powder having an average particle size of 0.6 μm. Thereafter, a predetermined amount of a binder was added to form a slurry, which was granulated using a spray granulator to obtain spherical granules.

Next, this spherical granule was press-molded to obtain a molded body having a predetermined shape. And after performing the binder removal process in the range of 600 degreeC in the range of 600 degreeC by the obtained molded object, after making this into a degreased body, this is hold | maintained at the maximum temperature of 1000 degreeC for 3 hours, and is baked. Obtain ferrite sintered body of each sample.

  Then, a coated lead wire having a wire diameter of 0.2 mm was wound 10 times around the entire circumference of the ring-shaped sample, and the magnetic permeability at a frequency of 100 kHz was measured using an LCR meter. Further, the Curie temperature Tc was measured by a bridge circuit method using an LCR meter.

  Furthermore, the surface of each sample processed as a measurement surface, and using a SEM, a reflected electron image was taken at a magnification of 2000 times, and six straight lines were drawn on the obtained photograph, and the straight lines crossed. The number of crystal grains and the total length of each crystal were measured, and the average crystal grain size was determined by a linear crossing method in which the total length of each crystal was divided by the number of each crystal.

Further, for each sample, the content of Fe, Ni, Zn and Cu was obtained using ICP, converted into Fe ₂ O ₃ , ZnO, NiO and CuO, respectively, and the molar value was calculated from the respective molecular weights. The occupation ratio with respect to 100 mol% in total was calculated. Also, using ICP, La,
The content of Pr is obtained, converted into La ₂ O ₃ and Pr ₂ O ₃ , respectively, and the content of all components constituting the ferrite sintered body is obtained. Converted to value. The results are shown in Table 1.

  From Table 1, sample no. 1 to 10 ferrite sintered bodies had an average crystal grain size exceeding 10 μm. In addition, Sample No. in which the auxiliary component was added before calcination was used. 11-20 ferrite sintered bodies had an average crystal grain size exceeding 6 μm.

In contrast, sample no. Nos. 21 to 51 have an average crystal grain size of 6 μm or less, and the average crystal grain size is small.
Sample No. 21, 24 to 28, 31 to 34, 37, 38, 41, 42, and 45 to 50 have an average crystal grain size of 6 μm or less, and their main component compositions are oxides of Fe, Ni, Zn, and Cu, respectively. When the total of the main components converted into 100 is 100 mol%, Fe is 47.5 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ , and Ni is 12.5 mol% or more and 17.6 mol% in terms of NiO. Hereinafter, Zn is 27.1 mol% or more and 32.8 mol% or less in terms of ZnO, and Cu is 3.6 mol% or more and 8 mol% or less in terms of CuO, and oxides of La and Pr are oxidized as subcomponents. wherein at least one of a product, content to total 100 wt% of the main component, La and _La 2 _{O 3} in terms of, Pr and _Pr 2 _{O 3} in terms of total 0.01 wt% to 0.60 wt% or less was By permeability 450 or more and the Curie temperature was 140 ° C. or higher.

  In the same manner as in Example 1, Sample No. 5, 15 and 32 were prepared, the surface was polished under the same conditions, and the number of grains removed was confirmed on the polished surface. As a result, sample no. No. 5 is the most common, and sample no. 32 gave the least result. From this result, it was found that the ferrite sintered body according to the present invention is less shed by processing.

  And from these results, the ferrite sintered body of the present invention has this ferrite sintered body as a core, and the core alone, or a metal wire wrapped around this core, an inductor, a transformer for the purpose of insulation and transformation, It turned out that it can be used conveniently for a ballast and an electromagnet. Further, it has been found that the filter can be suitably used as a noise filter for preventing an electronic component from being adversely affected by noise generated from an electric circuit incorporated in an electronic device or the like.

1: Ferrite sintered body 2: External electrode 10: Noise filter

Claims (4)

An oxide containing Fe, Ni, Zn and Cu is a main component, and as an auxiliary component, it contains at least one of an oxide of La and an oxide of Pr, and the content of the main component is 100% by mass in total. The total of La converted to La ₂ O ₃ and Pr converted to Pr ₂ O ₃ is 0.01 mass% or more and 0.60 mass% or less, and the average crystal grain size is 6 μm or less (excluding 0 μm). Featuring sintered ferrite. When the total amount of the main components obtained by converting Fe, Ni, Zn, and Cu into oxides is 100 mol%, Fe is 47.5 mol% or more and 50 mol% or less in terms of Fe ₂ O _3. Ni is 12.5 mol% or more and 17.6 mol% or less in terms of NiO, Zn is 27.1 mol% or more and 32.8 mol% or less in terms of ZnO, and Cu is 3.6 mol% or more and 8 mol or less in terms of CuO. The ferrite sintered body according to claim 1, wherein the ferrite sintered body is at most%.   The ferrite sintered body according to claim 1 or 2, wherein the subcomponent is an oxide of La.   A noise filter comprising electrodes provided inside and outside of the ferrite sintered body according to any one of claims 1 to 3.

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