JP5882811B2 - Ferrite sintered body and pulse transformer core comprising the same - Google Patents

Description

  The present invention relates to a ferrite sintered body and a core for a pulse transformer in which a metal wire is wound around the ferrite sintered body.

  Conventionally, ferrite sintered bodies have been used as cores for inductors, transformers, ballasts, electromagnets, noise filters, etc., and as cores for pulse transformers used in LAN interface units of various IT-related devices. As the ferrite sintered body as the core, a Mn—Zn ferrite sintered body having a high magnetic permeability has been widely used.

  However, the Mn-Zn ferrite sintered body has a low specific resistance (electrical resistance) and cannot be wound directly on the ferrite sintered body serving as a core, and an insulator must be interposed therebetween. Therefore, workability of the metal wire winding was bad. In addition, since an insulator must be interposed, it has been difficult to cope with downsizing and thinning, which have been increasingly demanded in recent years.

  On the other hand, a Ni—Zn ferrite sintered body is known as having a specific resistance approximately two orders of magnitude higher than that of the Mn—Zn ferrite sintered body.

For example, Patent Document 1 discloses that Fe is converted to Fe ₂ O ₃ at 45.0 to 50.0 mol%, Ni is converted to NiO at 5.0 to 10.0 mol%, Cu is converted to CuO at 5.0 to 15.0 mol%, When Zn is converted to ZnO, at least one metal selected from 25.0 to 35.0 mol%, Mo, W, V, Cr, Mg, Ca, Sr and Ba is MoO ₃ , WO, V ₂ O ₅ , Cr ₂ O, respectively. ₃ , oxide magnetic materials containing 0.1 to 3.0 mol% in total in terms of MgO, CaO, SrO and BaO and 0.01 to 3.0 mol% in terms of Li in terms of Li ₂ O have been proposed.

JP-A-8-208233

  However, although the oxide magnetic material described in Patent Document 1 has a high specific resistance, the magnetic permeability shown in the examples is about 2000 at the highest, so it can respond to miniaturization and thinning. I couldn't. In addition, in addition to miniaturization and thinning, for example, in a pulse transformer using a core made of a ferrite sintered body, a part of the energy of the applied magnetic field is released to the outside as heat. Therefore, it is required that the efficiency does not decrease and the temperature does not increase. Therefore, in order to meet this demand, a material that can improve the magnetic permeability and reduce the core loss at room temperature is required.

  An object of the present invention is to provide a ferrite sintered body having a high magnetic permeability and a small core loss at room temperature, and a core for a pulse transformer formed by winding a metal wire around the ferrite sintered body.

As a main component, Fe is 49.5 mol% or more and 49.8 mol% or less in terms of Fe ₂ O ₃ , Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, Ni is 5 mol% or more and 15 mol% or less in terms of NiO Cu is 4 mol% or more and 9 mol% or less in terms of CuO, with respect to 100 mass% of the main component, W is WO ₃ , Mo is MoO ₃ , and Mn is MnO ₂ in terms of 0.01 mass% or more. It is characterized by containing 1% by mass or less.

  The pulse transformer core of the present invention is characterized in that a metal wire is wound around the ferrite sintered body having the above-described configuration.

  According to the ferrite sintered body of the present invention, since it is made of a material that can improve the magnetic permeability and reduce the core loss at room temperature, the ferrite sintered body has a high magnetic permeability and a small core loss at room temperature. Can do.

  According to the pulse transformer core of the present invention, a metal wire is wound around the ferrite sintered body having the above-described configuration having a high magnetic permeability and a small core loss at room temperature. It can be an excellent pulse transformer core with high efficiency and reliability.

An example of the ferrite sintered compact of this embodiment is shown, (a) is a perspective view of a toroidal core, (b) is a perspective view of a bobbin core.

  Hereinafter, the ferrite sintered body of the present invention and a core for a pulse transformer including the same will be described.

  The ferrite sintered body of the present embodiment is used for the purpose of, for example, inductors, transformers, ballasts and electromagnets for noise insulation and voltage reduction, by winding a metal wire with the ferrite sintered body as a core. This is used for the core of noise filters and pulse transformers.

  Here, there are various shapes of ferrite sintered bodies as cores. For example, the ring-shaped toroidal core 1 shown in the perspective view of FIG. 1A or the bobbin shown in the perspective view of FIG. Shaped bobbin core 2 and the like.

Such a ferrite sintered body is required to have a high magnetic permeability (μ) and a small core loss at room temperature. Fe as a main component is 49 mol in terms of Fe ₂ O _3. From 50% to 50% by mole, Zn from 32% to 36% by mole in terms of ZnO, Ni from 5% to 15% by mole in terms of NiO, and Cu from 4% to 9% by mole in terms of CuO, Ferrite sintering satisfying the above-mentioned requirements by including 0.01% by mass to 1.0% by mass in terms of W converted to WO ₃ , Mo converted to MoO ₃ , and Mn converted to MnO ₂ with respect to 100% by mass of the main component. It can be a body.

  Here, the reason why the main component is in the above-described composition range is that a ferrite sintered body having a high magnetic permeability and a small core loss at room temperature can be obtained. The main component refers to a component that accounts for 95% or more of the components constituting the ferrite sintered body.

On the other hand, there is the following tendency outside the composition range described above. When Fe is less than 49 mol% in terms of Fe ₂ O ₃ , the magnetic permeability is low, and when it exceeds 50 mol%, core loss increases. Further, when Zn is less than 32 mol% in terms of ZnO, the magnetic permeability is low, and when it exceeds 36 mol%, core loss increases. Further, when Ni is less than 5 mol% in terms of NiO, the characteristics as ferrite cannot be expressed, and when it exceeds 15 mol%, the magnetic permeability is lowered. Cu is 4 in terms of CuO.
If it is less than mol%, the magnetic permeability is low, and if it exceeds 9 mol%, the properties as ferrite cannot be expressed.

The ferrite sintered body of the present embodiment, contains the main component with respect to 100 wt%, W and WO _3, Mo and _MoO 3, Mn less 1.0 wt%, respectively 0.01 wt% or more value converted into MnO ₂ As a result, the magnetic permeability can be further improved, and the core loss at room temperature can be further reduced. In particular, W is converted to WO ₃ by 0.4 to 0.6 mass%, Mo is converted to MoO ₃ by 0.05 to 0.2 mass%, and Mn to MnO.
_The value converted to ₂ is preferably 0.05% by mass or more and 0.2% by mass or less.

Here, W contributes to reducing the core loss at room temperature. When W is less than 0.01% by mass in terms of WO ₃ , the content is too small, so the effect of reducing the core loss at room temperature is small, and when it exceeds 1.0% by mass, the content is too high and transparent. There is a tendency for magnetic susceptibility to be low.

Further, Mo has an effect of promoting the grain growth of the crystal composed of the main component, and the magnetic permeability can be improved by growing the crystal composed of the main component. On the other hand, when Mo is less than 0.01% by mass in terms of MoO ₃ , the content is too small, so the effect of promoting grain growth is small, and when it exceeds 1.0% by mass, the content is too high. However, the magnetic permeability tends to be low.

Moreover, Mn contributes to increasing the magnetic permeability. This is because MnO ₂ and Mn ₃ O ₄ which are oxides of Mn change in valence to MnO by heating, and an excess oxygen component accompanying this valence change fills oxygen defects in the ferrite sintered body. it is conceivable that. On the other hand, when Mn is less than 0.01% by mass in terms of MnO ₂ , the effect of increasing the magnetic permeability is small, and when it exceeds 1.0% by mass, the content tends to be low because the content is too large. is there.

In addition to the main component and W, Mo, and Mn described above, an oxide of Si or an oxide of Ca may be included. The specific resistance can also be increased by including this Si oxide or Ca oxide. When Si oxide or Ca oxide is included, the total of Si converted to SiO ₂ and Ca converted to CaO is preferably 0.4 mass% or less with respect to 100 masses of the main component.

The main component of the ferrite sintered body of the present embodiment is that Fe is 49 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ , Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, and Ni is NiO equivalent 5 mol% or more and 15 mol% or less and Cu is contained in an amount of 4 mol% or more and 9 mol% or less in terms of CuO, using an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer or a fluorescent X-ray analyzer. , Zn, Ni, and Cu can be obtained and converted into Fe ₂ O ₃ , ZnO, NiO, and CuO, respectively, and converted into mol% using these converted values.

Further, W, for the content of Mo and Mn, using an ICP emission spectrophotometer or fluorescence X-ray analyzer, W, Mo, determine the content of Mn, respectively _{WO 3,} MoO _3, converted to MnO ₂ Then, a value for 100% by mass of the main component may be calculated. The same applies to Si and Ca.

  In the ferrite sintered body of the present embodiment, Ni is preferably more than 10 mol% and 15 mol% or less in terms of NiO. Thereby, the magnetic permeability can be further increased, and the core loss at room temperature can be reduced, so that a ferrite sintered body having more excellent characteristics can be obtained.

Moreover, in the ferrite sintered body of the present embodiment, it is preferable that Fe is 49.5 mol% or more and 49.8 mol% or less in terms of Fe ₂ O ₃ . Thereby, the magnetic permeability on the high temperature side can be increased, and the characteristics as a transformer can be improved.

  Next, the manufacturing method of the ferrite sintered body of the present embodiment will be described in detail below.

In the method of manufacturing a ferrite material according to the present embodiment, first, as a starting material, an oxide of Fe, Zn, Ni, Cu, W, Mo, and Mn or a metal salt such as carbonate or nitrate that generates an oxide by firing is used. prepare. At this time, as the average particle size, for example, Fe is iron oxide (Fe ₂ O ₃ ), Zn is zinc oxide (ZnO), Ni is nickel oxide (NiO), Cu is copper oxide (CuO), and W is tungsten oxide ( When WO ₃ ), Mo is molybdenum oxide (MoO ₃ ), and Mn is manganese oxide (MnO ₂ ), they are 0.5 μm or more and 5 μm or less, respectively.

Then, the starting materials constituting the main component are weighed to a desired amount, pulverized and mixed with a ball mill or a vibration mill, and then calcined at a maximum temperature of 700 ° C. or higher and 1000 ° C. or lower for 2 hours or longer to obtain a calcined body. obtain.

Next, the calcined body, tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), and manganese oxide (MnO ₂ ) having an average particle size of 0.5 to 5 μm are put into a ball mill or a vibration mill and pulverized and mixed. Thus, the core loss at room temperature can be reduced by adding tungsten oxide (WO ₃ ) after calcination, although the reason is not clear. Further, by adding molybdenum oxide (MoO ₃ ) after calcination, crystal grain growth consisting of the main component can be promoted, and the magnetic permeability can be increased.

Note that the manganese oxide (MnO _2), may be added before calcination. When it is desired to reduce eddy current loss as a high electric resistance, at least one of a predetermined amount of CaO and SiO ₂ may be added during pulverization and mixing after calcination.

  Next, a predetermined amount of a binder is added to the calcined powder after pulverization and mixing to form a slurry, and spherical granules granulated using a spray granulator (spray dryer) are obtained. Next, this spherical granule is press-molded to obtain a molded body having a predetermined shape.

  Thereafter, the molded body is degreased in a degreasing furnace in the range of 400 to 800 ° C. to obtain a degreased body, and then this is held in a firing furnace at a maximum temperature of 1000 to 1200 ° C. for 2 to 5 hours and fired. By doing so, the ferrite sintered body of the present embodiment can be obtained.

Next, a method for measuring magnetic permeability and core loss will be described. First, the magnetic permeability may be measured under the condition of a frequency of 100 kHz using an LCR meter. At this time, as a sample, for example, a ring-shaped toroidal core 1 made of a ferrite sintered body shown in FIG. 1A having an outer diameter of 13 mm, an inner diameter of 7 mm, and a thickness of 3 mm is used. A metal wire having a wire diameter of 0.2 mm is wound 10 times around the entire circumference of the wire portion 1a.

The core loss may be measured using a BH analyzer (for example, SY-8232 manufactured by IWATSU) under the conditions of a magnetic flux density of 150 mT and a frequency of 50 kHz. As a sample for measuring core loss, for example, a ring-shaped toroidal core 1 made of a ferrite sintered body shown in FIG. 1A having an outer diameter of 13 mm, an inner diameter of 7 mm, and a thickness of 3 mm is used. As the winding and the secondary winding, a metal wire having a wire diameter of 0.2 mm wound around the entire circumference of the winding portion 10a of the toroidal core 1 is used 10 times.

  And the core for pulse transformers of this embodiment can be produced by winding a metal wire around the ferrite sintered body of this embodiment. The ferrite sintered body of the present embodiment has a high magnetic permeability and a small core loss at room temperature, so that it can cope with downsizing and thinning, and has excellent efficiency and reliability, for an excellent pulse transformer. Can be a core.

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

  In order to confirm the change in characteristics due to the inclusion of W, Mo and Mn, ferrite sintered bodies whose main components are shown in Table 1 were first prepared.

Table 1 shows the powders of iron oxide (Fe ₂ O ₃ ), zinc oxide (ZnO) and nickel oxide (NiO) having an average particle diameter of 1 μm and copper oxide (CuO) powder having an average particle diameter of 3 μm. The mixture was weighed so as to have a ratio, pulverized and mixed with a ball mill, and calcined at 750 ° C. to obtain a calcined body. The calcined body was pulverized to obtain a calcined powder. Next, this calcined powder was pulverized with a vibration mill, and a binder was added to form a slurry, which was granulated with a spray granulator (spray dryer) to obtain spherical granules. Then, this spherical granule was compression molded by a press molding method to obtain a molded body having the shape of the toroidal core 1 shown in FIG.

Next, this molded body was held in a degreasing furnace at a maximum temperature of 600 ° C. for 5 hours and subjected to a binder removal treatment to obtain a degreased body. Thereafter, the degreased body was fired in a firing furnace at a maximum temperature of 1000 to 1200 ° C. for 2 hours in an air atmosphere. Thereafter, grinding was performed, and a toroidal sample No. 1 having an outer diameter of 13 mm, an inner diameter of 7 mm, and a thickness of 3 mm was obtained. 1 to 27 ferrite sintered bodies were obtained.

Then, after winding a metal wire having a wire diameter of 0.2 mm 10 times around the entire circumference of the winding portion 10a of each sample, the magnetic permeability at a frequency of 100 kHz was measured using an LCR meter. In addition, after winding the primary winding and the secondary winding, which are metal wires having a diameter of 0.2 mm, around the entire circumference of the winding portion 10a of each sample 10 times, the magnetic flux density is measured using a BH analyzer. The core loss at 150 mT and a frequency of 50 kHz was measured.

Also, for each sample, using an ICP emission spectrophotometer, seeking Fe, Zn, Ni, the content of Cu, respectively _{Fe 2 O 3, ZnO, NiO} , in terms of CuO, using the converted value Converted to mol%.

  Sample No. Table 1 shows the main component molar ratio, magnetic permeability, and core loss of 1 to 27.

Next, sample No. After obtaining calcined powders by the same method as that for producing Nos. 1 to 27, tungsten oxide (
WO ₃ ), molybdenum oxide (MoO ₃ ), and molybdenum oxide (MnO ₂ ) are added. Sample Nos. 1 and 27 having the same shape by the same manufacturing method as those used when manufacturing Nos. 1 to 27. 28 to 54 ferrite sintered bodies were obtained.

Also. Sample No. Tungsten oxide (WO ₃ ) using the calcined powder obtained by the same method as that for producing No. 4 so that the content shown in Table 3 is obtained with respect to 100% by mass of the calcined powder.
Molybdenum oxide (MoO ₃ ) and molybdenum oxide (MnO ₂ ) are added, and the subsequent steps are performed in accordance with sample No. Sample Nos. 1 and 27 having the same shape by the same manufacturing method as those used when manufacturing Nos. 1 to 27. 55
˜78 ferrite sintered bodies were obtained.

Then, the magnetic permeability and core loss were measured by the same method as described above. Also, for each sample, using an ICP emission spectrophotometer, seeking Fe, Zn, Ni, the content of Cu, respectively _{Fe 2 O 3, ZnO, NiO} , in terms of CuO, using the converted value Converted to mol%. Furthermore, using the same ICP emission spectroscopic analyzer, the contents of W, Mo, and Mn were determined, converted into WO ₃ , MoO ₃ , and MnO ₂ , respectively, and values for 100% by mass of the main component were calculated. Regarding the molar ratio of the main components, the contents of WO ₃ , MoO ₃ and MnO ₂ , the magnetic permeability and the core loss, the sample No. The results of 28 to 54 are shown in Table 2, and sample No. The results for 55-78 are shown in Table 3.

  Also, the rate of increase in magnetic permeability was calculated. As a method for calculating the rate of increase in magnetic permeability, the magnetic permeability shown in Table 1 to which W, Mo, and Mn are not added is a basic value, the main component corresponds to Table 1, and W, Mo, and Mn are added. This was carried out using the permeability value of the sample shown in FIG. Specifically, Sample No. 1 and sample no. As an example, (the permeability of sample No. 28−the permeability of sample No. 1) / sample No. Calculated as a permeability of 1. Furthermore, the reduction rate of core loss was calculated. As a calculation method of the core loss reduction rate, Sample No. 1 and sample no. As an example, (core loss of sample No. 1−core loss of sample No. 28) / sample no. 1 core loss. The results are shown in Table 2.

  In the calculation of the rate of increase in magnetic permeability and the rate of decrease in core loss shown in Table 3, the basic numerical values are sample Nos. A permeability of 4 (3020) and a core loss (360) were used. The results are shown in Table 3.

From the results of Table 1, Fe is 49 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ , Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, and Ni is 5 mol% or more and 15 mol% or less in terms of NiO. , Cu does not satisfy at least one of the ranges of 4 mol% or more and 9 mol% or less in terms of CuO. For 1, 6, 7, 11, 12, 22, 23 and 27, the magnetic permeability was less than 2000. Further, Sample No. with Fe exceeding 50 mol% in terms of Fe ₂ O ₃ was obtained. 6, the core loss at room temperature exceeded 500. Compared to these samples, sample No. 2-5, 8-10, 13-21 and 24
As for -26, all had a magnetic permeability of 2000 or more and a core loss at room temperature of 500 or less. From these results, Fe is 49 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ , Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, and Ni is 5 mol% or more and 15 mol or less in terms of NiO.
It was found that a ferrite sintered body having high magnetic permeability and low core loss at room temperature can be obtained by containing 4 mol% or less and 9 mol% or less of Cu in terms of CuO in terms of CuO.

Next, from the results in Table 2, in addition to the main component in Table 1, 0.5 wt% of W in terms _of WO _3, 0.1 wt% of Mo calculated as MoO ₃ and Mn contained 0.1% by mass MnO ₂ in terms of By
It was found that the magnetic permeability can be improved and the core loss at room temperature can be reduced.

And as a main component, Fe is 49 mol% or more and 50 mol% or less in terms of Fe ₂ O ₃ , Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, Ni is 5 mol% or more and 15 mol% or less in terms of NiO ,
Cu is contained in an amount of 4 mol% or more and 9 mol% or less in terms of CuO, and W is WO ₃ , Mo is MoO ₃ , and Mn is converted to MnO ₂ with respect to 100 mass% of the main component. Sample No. containing less than mass%. 29-32, 35-37, 40-48, and 51-53 can improve the magnetic permeability by 30% or more and reduce the core loss at room temperature by 30% or more, and are ferrite sintered bodies having excellent characteristics. I understood. These sample Nos. 29-32, 35-37, 40-48 and 51-53 all have a specific resistance of 10 ⁷ Ω · m or more, and occurred when these ferrite sintered bodies were used as a core for a pulse transformer. It was found that eddy current loss due to heat generation of ferrite sintered body by eddy current can be reduced.

  Further, as is clear from the results of the magnetic permeability and core loss of the samples having the same Fe and Zn contents, when Ni is more than 10 mol% and not more than 15 mol% in terms of NiO, the magnetic permeability is higher and at room temperature. It was found that the core loss can be made smaller.

Next, from the results shown in Table 3, in order to improve the magnetic permeability and reduce the core loss, 0.01 mass% in terms of W as WO ₃ , Mo as MoO ₃ , and Mn as MnO ₂ with respect to 100 mass% of the main composition, respectively. It was found that containing 1.0% by mass or less is important.

Next, by the same production method as in Example 1, the main component is the molar ratio shown in Table 4, W is 0.5% by mass in terms of WO ₃ , Mo is 0.1% by mass in terms of MoO ₃ , and Mn is in terms of MnO ₂ Sample No. containing 0.1% by mass 79 to 84 ferrite sintered bodies were obtained. The molar ratios and contents shown in Table 4 were calculated using an ICP emission spectroscopic analyzer as in Example 1.

And about each sample, the magnetic permeability of the high temperature side (60 to 100 degreeC) was measured. For this measurement method, a metal wire having a wire diameter of 0.2 mm is applied to the entire circumference of the winding portion 10a of each sample.
After winding, it was put in a thermostat. And it was set as the conditions hold | maintained for 30 minutes in 10 degreeC increments in 60 to 100 degreeC, and the magnetic permeability in each temperature was measured using the LCR meter. The frequency was 100 kHz. The results are shown in Table 4.

As a result of Table 4, sample No. 80 to 83 have high permeability on the high temperature side, and it has been confirmed that the characteristics as a transformer are further improved. Therefore, in the main component, Fe is 49.5 mol% or more and 49.8 mol% or less in terms of Fe ₂ O _3. It was found that it was preferable to consist of

1: Toroidal core 1a: Winding part 2: Bobbin core 2a: Winding part

Claims (3)

As a main component, Fe is converted to 49 _{2 in} terms of Fe ₂ O ₃ . 5 mol% or more and 49.8 mol% or less, Zn is 32 mol% or more and 36 mol% or less in terms of ZnO, Ni is 5 mol% or more and 15 mol% or less in terms of NiO, and Cu is 4 mol% or more and 9 mol or less in terms of CuO. % Or less,
Ferrite calcination characterized by containing 0.01% by mass or more and 1.0% by mass or less in terms of W in terms of WO ₃ , Mo in terms of MoO ₃ , and Mn in terms of MnO ₂ with respect to 100% by mass of the main component. Union.   2. The ferrite sintered body according to claim 1, wherein the Ni content is more than 10 mol% and not more than 15 mol% in terms of NiO. A core for pulse transformer, comprising a ferrite sintered body according to claim 1 or 2 wound with a metal wire.

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