JP4670435B2 - Ferrite sintered body, manufacturing method thereof and coil component - Google Patents

Description

  The present invention relates to a ferrite sintered body, a manufacturing method thereof, and a coil component.

  Ferrite cores composed of sintered ferrite are mainly used for coil parts, sensors, antennas, deflection yokes and other parts, and electrical products incorporating these parts have been mainly used indoors until now. It was.

However, due to the rapid spread of electric products such as mobile phones and notebook computers, and the expansion of applications as automotive parts in recent years, products with built-in coil parts will be used outdoors. It has become to. Naturally, the coil components employed in these outdoor products are required to have characteristics that can withstand harsh usage environments, particularly temperature changes. As a characteristic specifically required for the coil component used in such an environment and application, there is a small change in inductance in an operating temperature range, and preferably no change at all. In order to meet this requirement, it is necessary to make the relative temperature coefficient α μ _ir of the initial permeability μ _i of the ferrite core as small as possible. Here, the relative temperature coefficient αμ _ir is a value expressed by Equation 1 described later, and is a ratio of a change amount of the initial permeability to a temperature change.

Conventionally, as a ferrite core having such characteristics, Ni—Cu—Zn-based ferrite is mainly used, and 0.2 to 0.8 wt% of Nb ₂ O ₅ , 0.3 to 1.2 wt. A sintered body of an oxide magnetic material to which any one of% Ta ₂ O ₅ and 0.15 to 1.35 wt% MoO ₃ is added is known (for example, see Patent Document 1 below). According to Patent Document 1, by setting the composition of the oxide magnetic material in the sintered body as described above, the relative temperature coefficient αμ _ir of the initial permeability μ _i in the temperature range of −25 to 85 ° C. is 0.5 to A ferrite sintered body having a value of 2.9 ppm / ° C. has been realized.
Japanese Patent Laid-Open No. 5-3112

By the way, in recent years, coil components used in automobile electrical products such as tire pressure sensors and engine room control circuits have a higher initial permeability temperature characteristic than coil components used in other applications. There are more demanding requirements. For example, a tire pressure sensor is required to maintain high-precision pressure detection accuracy even in a cold region that reaches -40 ° C. Further, the engine room is assumed to reach 150 ° C. in a high-temperature atmosphere such as a desert, and it is required to maintain high temperature detection accuracy in such a high-temperature atmosphere as well.

  However, in the ferrite sintered body described in Patent Document 1 described above, a low relative temperature coefficient can be realized in the temperature range of −25 to 85 ° C., but a low relative temperature coefficient is realized particularly in a region outside the above temperature range. It tends to be impossible. As a result, the coil component may not operate properly in a region outside the temperature range. For example, the usable frequency band may be changed due to the severe environmental temperature change as described above, and may not operate properly. Therefore, the use of the coil component is limited, and there is a problem that the versatility is poor.

Further, Nb ₂ O ₅ , Ta ₂ O ₅ , MoO _{3 and the} like are expensive, and there is a problem in that the cost of the coil component is increased.

  The present invention has been made in view of the above circumstances, and can appropriately operate a coil component over a wide temperature range of −40 to 150 ° C., can be used in a wide range of applications, and can be manufactured at a low cost. An object of the present invention is to provide a bonded body, a manufacturing method thereof, and a coil component.

In order to solve the above problems, the sintered ferrite body of the present invention is
And 46.0～49.0Mol% iron oxide calculated as Fe ₂ O _3,
20.0-30.0 mol% zinc oxide in terms of ZnO,
1.0 to 9.0 mol% copper oxide in terms of CuO;
0.1 to 1.0 mol% manganese oxide in terms of Mn ₂ O ₃ ,
Fe ₂ O _3, ZnO, consists of a nickel oxide of the remainder except for CuO and _Mn 2 _{O 3,}
The molar ratio of Fe ₂ O ₃ represented by ZnO / Fe ₂ O ₃ and ZnO is 0.54 to 0.67,
The average crystal grain size D50 is 5 to 15 μm,
The relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C.,
It is characterized by that.

Moreover, the method for producing a ferrite sintered body of the present invention is as follows.
And 46.0～49.0Mol% iron oxide calculated as Fe ₂ O _3,
20.0-30.0 mol% zinc oxide in terms of ZnO,
1.0 to 9.0 mol% copper oxide in terms of CuO;
0.1 to 1.0 mol% manganese oxide in terms of Mn ₂ O ₃ ,
The remaining nickel oxide excluding Fe ₂ O ₃ , ZnO, CuO and Mn ₂ O ₃ ,
And calcining steps molar ratio of _Fe 2 _{O 3} and ZnO, represented by ZnO / _Fe 2 _{O 3} to obtain a raw material mixture calcined to pre-sintered product is from 0.54 to 0.67,
A pulverizing step of pulverizing the calcined product to obtain a pulverized powder;
Molding the pulverized powder to obtain a molded body;
Including a main firing step of subjecting the molded body to main firing to obtain a ferrite sintered body,
In the pulverization step, the calcined product is pulverized so that the average crystal particle size D90 in the particle size distribution for the primary particle size of the pulverized powder is 5 μm or less,
In the main firing step, the pulverized powder is fired so that the average grain size D50 in the ferrite sintered body is 5 to 15 μm, whereby the relative temperature coefficient αμ _ir of the initial magnetic permeability μi is −40 to 20 A ferrite sintered body having a temperature range of −2 to 2 ppm / ° C. over the temperature range of 20 ° C. and a temperature range of 20 to 150 ° C. is obtained.

  Moreover, the coil component of the present invention is characterized by including the above-described ferrite sintered body.

  In the present invention, the “primary particle diameter of the pulverized powder” refers to the particle diameter per one pulverized powder, and the particle diameter of the aggregated particles obtained by agglomerating the pulverized powder, that is, secondary particles of the pulverized powder. Does not include diameter.

  In the present invention, the “average crystal particle size D90 in the particle size distribution for the primary particle size of the pulverized powder” means that the pulverized powder is observed with a visual field of 46 μm × 35 μm (magnification: 5500 times) using a scanning electron microscope (SEM). The SEM image observed at this time is a value calculated by analyzing the image analysis apparatus IP-1000 manufactured by Asahi Kasei.

  Furthermore, in the present invention, the “average grain size D50 of the sintered ferrite body” means that the cross section of the sintered ferrite body is observed with a visual field of 85 μm × 64 μm (magnification: 1500 times) using SEM. The value calculated by analyzing the SEM image with the image analysis apparatus IP-1000 manufactured by Asahi Kasei shall be said.

According to the ferrite sintered body of the present invention, the relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. The coil components can be properly operated over a wide temperature range of -40 to 150 ° C. For this reason, the ferrite sintered body of the present invention can be used as a core of a coil component for automobiles, such as a tire air pressure sensor and a control circuit in an engine room, or as a coil component other than those for automobiles. Can be used. Moreover, since an expensive component is not included, it can be provided at a relatively low cost.

Further, according to the method for producing a ferrite sintered body of the present invention, the relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. It is possible to effectively produce a ferrite sintered body at / ° C. Moreover, the ferrite sintered body obtained by this manufacturing method can operate a coil component appropriately over a wide temperature range of −40 to 150 ° C. For this reason, the ferrite sintered body of the present invention can be used as a core of a coil part for automobiles and a coil part other than for automobiles, such as a tire pressure sensor and a control circuit in an engine room, and is widely used. Can be used for applications. Moreover, since an expensive component is not included, it can be manufactured at a relatively low cost.

According to the coil component of the present invention, the relative temperature coefficient αμ _ir of the initial magnetic permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. in the ferrite sintered body. Therefore, it is possible to operate properly over a wide temperature range of −40 to 150 ° C. Therefore, the coil component of the present invention can be used as a coil component for automobiles or a coil component other than for automobiles, such as a tire pressure sensor and a control circuit in an engine room, and can be used for a wide range of applications. Moreover, since an expensive component is not included, it can be provided at a relatively low cost.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 1 is a perspective view showing an embodiment of a coil component of the present invention. As shown in FIG. 1, the coil component 10 includes a drum-type ferrite core (sintered body core) 12 and a copper wire (winding) 14 with an insulation coating wound around the ferrite core 12. .

Ferrite core 12 is composed of a ferrite sintered body, ferrite sintered body, and 46.0～49.0Mol% iron oxide calculated as Fe ₂ O _3, oxides of 20.0～30.0Mol% calculated as ZnO Zinc , 1.0 to 9.0 mol of copper oxide in terms of CuO, 0.1 to 1.0 mol% of manganese oxide in terms of Mn ₂ O ₃ , Fe ₂ O ₃ , ZnO, CuO, Mn ₂ O ₃ It consists and excluding the rest of the nickel oxide (NiO). The molar ratio of Fe ₂ O ₃ and ZnO represented by ZnO / Fe ₂ O ₃ is 0.54 to 0.67, and the relative temperature coefficient αμ _ir of the initial permeability μi is −40 to 20 Both are −2 to 2 ppm / ° C. over the temperature range of 20 ° C. and the temperature range of 20 to 150 ° C.

According to this coil component 10, the relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. in the ferrite core 12. Therefore, it becomes possible to operate appropriately over a wide temperature range of −40 to 150 ° C. For this reason, the coil component 10 can be used as an automotive coil component or a coil component other than an automotive component, such as a tire pressure sensor or a control circuit in an engine room, and can be used for a wide range of applications.

  The reason why the ferrite sintered body has the above composition is as follows.

That is, when the content of Fe ₂ O ₃ in the ferrite sintered body is less than 46.0 mol%, the density of the sintered body is reduced, and the coil component 10 operates properly over a wide temperature range of −40 to 150 ° C. Can not be made. For this reason, the use of the coil component 10 is limited, and the coil component is inferior in versatility. On the other hand, when the content ratio of Fe ₂ O ₃ in the ferrite sintered body exceeds 49.0 mol%, Fe ₃ O ₄ is remarkably precipitated and the sintered body density is lowered, so that the mechanical strength of the ferrite core 12 is reduced. descend. _{On the} other hand, if the content of Fe ₂ O ₃ in the ferrite sintered body exceeds 49.0 mol%, the specific resistance as the core is remarkably lowered, and the eddy current is generated, and the proper operation is not possible in the high frequency region.

  Further, when the content of CuO in the ferrite sintered body is less than 1.0 mol%, the sintered body density is lowered, so that the mechanical strength of the ferrite core 12 is lowered. On the other hand, when it exceeds 9.0 mol%, the specific resistance of the core is lowered, and the eddy current is generated, so that the core does not operate properly in the high frequency region.

  On the other hand, if the ZnO content is less than 20.0 mol%, the initial permeability decreases. On the other hand, when the ZnO content exceeds 30.0 mol%, the Curie temperature is lowered, and demagnetization occurs under the influence of the temperature.

Further, by containing 0.1 to 1.0 mol% of Mn ₂ O ₃ , it becomes easy to control the crystal grain size at the time of the main firing, and a good temperature characteristic of initial permeability μ i can be obtained. Here, _Mn 2 _{O 3} content ratio can not be obtained the effect of _Mn 2 _{O 3} content is less than 0.1mol%, _Mn 2 _{O 3} exceeds 1.0 mol% and sintered body density decreases ferrite core 12 mechanical strength is reduced.

Further, if the total content of Fe ₂ O ₃ and Mn ₂ O _{3 in} the ferrite sintered body exceeds 50.0 mol%, the sintered body density decreases, so the mechanical strength of the ferrite core 12 decreases. Further, if the total content of Fe ₂ O ₃ and Mn ₂ O _{3 in} the ferrite sintered body exceeds 50.0 mol%, the specific resistance as a core is significantly reduced, and the generation of eddy currents causes a high frequency region. Will not work properly.

Further, in the ferrite sintered body, the balance excluding Fe ₂ O ₃ , ZnO, CuO, and Mn ₂ O ₃ contains NiO. This is because if the ferrite sintered body does not contain NiO, the specific resistance of the core is lowered, and the generation of eddy currents prevents proper operation in the high frequency region.

Furthermore, when the molar ratio of Fe ₂ O ₃ and ZnO represented by ZnO / Fe ₂ O ₃ is less than 0.54, the relative temperature coefficient αμir increases in the positive direction, and the molar ratio exceeds 0.67. The relative temperature coefficient αμir of 20 to 150 ° C. increases in the negative direction.

Furthermore, when the relative temperature coefficient αμ _ir of the initial magnetic permeability μi in the ferrite sintered body is out of the range of −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. , The coil component 10 may not operate properly over a temperature range of −40 to 150 ° C., which is inferior in versatility.

In the ferrite sintered body, the content of Fe ₂ O ₃ is preferably 46.0 to 49.0 mol%, more preferably 46.0 to 48.0 mol%, and the content of ZnO is preferably 20.0. -30.0 mol% More preferably, it is 25.0-30.0 mol%. The molar ratio of Fe ₂ O ₃ represented by ZnO / Fe ₂ O ₃ and ZnO is preferably 0.54 to 0.67, more preferably 0.54 to 0.64.

  In the ferrite sintered body, the average crystal grain size D50 (particle size at which the integrated value of the weight of the particles is 50%) is preferably 5 to 15 μm. When the average crystal grain size D50 is less than 5 μm, αμir tends to increase in the negative direction as compared with the case where the average crystal grain size D50 is 5 μm or more. On the other hand, when the average crystal grain size D50 exceeds 15 μm, the relative temperature coefficient αμir tends to increase in the positive direction as compared with the case where it is 15 μm or less.

Further, in addition to NiO, inevitable impurities may be contained in the balance excluding Fe ₂ O ₃ , ZnO, CuO, and Mn ₂ O ₃ .

  Next, the manufacturing method of the coil component 10 mentioned above is demonstrated.

  First, a method for manufacturing the ferrite core 12 constituting the coil component 10 will be described.

First, iron oxide α-Fe ₂ O ₃ , copper oxide CuO, zinc oxide ZnO, nickel oxide NiO, and manganese oxide Mn ₂ O ₃ are prepared, and these oxides are mixed to obtain a raw material mixture. At this time, the contents of Fe ₂ O ₃ , ZnO, CuO, and Mn ₂ O ₃ are 46.0 to 49.0 mol%, 20.0 to 30.0 mol%, 1.0 to 9.0 mol%, and 0.0, respectively. molar ratio of 1～1.0Mol% become so and _Fe 2 _{O 3} and ZnO, represented by ZnO / _Fe 2 _{O 3} is mixed with material such that from 0.54 to 0.67, the remainder It is mainly composed of NiO. In addition, you may mix another compound with the said oxide so that the composition ratio of each oxide component in the raw material mixture finally obtained may be in the said range in conversion to the said oxide. Each raw material is mixed so that it may become the said composition ratio as a final composition.

  Next, the raw material mixture is calcined to obtain a calcined product (calcining step). The calcination is usually performed in the air. The calcining temperature depends on the components constituting the raw material mixture, but is preferably 800 to 1100 ° C. Moreover, although calcining time is dependent on the component which comprises a raw material mixture, it is preferable to set it as 1-3 hours.

  Next, the obtained calcined product is pulverized by a ball mill or the like to obtain a pulverized powder (pulverization step). At this time, the calcined product is pulverized so that the average crystal grain size D90 in the particle size distribution for the primary particle size of the pulverized powder is 5 μm or less. In order to do so, specifically, the raw material mixture may be mixed and pulverized for 10 to 40 hours using a pulverizer such as a ball mill.

  Subsequently, the pulverized powder obtained as described above and a suitable binder such as polyvinyl alcohol are mixed and molded into the same shape as the ferrite core 12, that is, a drum shape to obtain a molded body.

  Next, the molded body is fired (main firing step). Thus, a ferrite core 12 made of a ferrite sintered body is obtained. At this time, the pulverized powder is sintered so that the average crystal grain size D50 in the ferrite core 12 is 5 to 15 μm. When D50 is less than 5 μm, the relative temperature coefficient αμir increases in the negative direction. On the other hand, when the average crystal grain size D50 exceeds 15 μm, the relative temperature coefficient αμir increases in the positive direction.

  The molded body may be fired in the air. Although a calcination temperature is dependent on the raw material which comprises pulverized powder, it is preferable that it is 900-1300 degreeC, and it is more preferable that it is 1000-1200 degreeC. Moreover, although baking time is dependent on the raw material which comprises pulverized powder, it is preferable to set it as 2 to 5 hours.

  Finally, a copper wire (winding) 14 with an insulation coating is wound around the ferrite core 12 obtained as described above. Thus, the manufacture of the coil component 10 is completed.

When the coil component 10 is manufactured as described above, the relative temperature coefficient αμ _ir of the initial permeability μi is over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. depending on the method for manufacturing the ferrite core 12. Can also effectively produce a ferrite sintered body having a concentration of -2 to 2 ppm / ° C. Moreover, the ferrite sintered compact obtained by the said manufacturing method can operate the coil component 10 appropriately over the wide temperature range of -40-150 degreeC. For this reason, the obtained coil component 10 can be used as a coil component other than for automobiles, such as a tire pressure sensor and a control circuit in an engine room, and can be used for a wide range of applications.

In the method for producing a ferrite sintered body, the molar ratio of Fe ₂ O ₃ and ZnO, the average crystal particle diameter D90 in the particle size distribution for the primary particle diameter of the pulverized powder, and the average crystal particle diameter D50 of the ferrite sintered body are State the reason for the provision.

The temperature characteristics of the initial permeability μ _i are affected by the composition, the Curie temperature determined by the composition, the stress balance between the crystal grains and the grain boundaries, and the magnetic anisotropy. Therefore, first, by defining the molar ratio of Fe ₂ O ₃ and ZnO represented by ZnO / Fe ₂ O ₃ , the influence of the composition and the Curie temperature is controlled.

Then, a sintered body having a desired average crystal grain size and average crystal grain size D50 is obtained by firing a molded body made of pulverized powder that does not include coarse particles that define the total average crystal grain size D90 under appropriate firing conditions. It is done. The microstructure of the sintered body thus obtained has no coarse crystal grains, and the sintered body becomes a uniform polycrystalline body having a uniform crystal grain diameter. As a result, the size of the crystal grains in the sintered body is increased. The variation in shape magnetic anisotropy resulting from the unevenness of the shape (particle diameter) and the shape is reduced, and the variation in the stress balance between the crystal grains and the grain boundaries is also reduced. At this time, by controlling the average crystal grain size D50 to an arbitrary size according to the firing conditions, the stress balance between the crystal grains and the grain boundaries when viewed as the entire sintered body can be controlled. This is because if the average crystal grain size D50 is small, the ratio of the grain boundary per unit volume increases, and conversely, if the average crystal grain size D50 is large, the ratio of the grain boundary decreases. Thus, the temperature characteristics of the initial permeability μ _i are good. For the above reasons, in the method for producing a ferrite sintered body, the molar ratio of Fe ₂ O ₃ and ZnO, the average crystal particle diameter D90 in the particle size distribution for the primary particle diameter of the pulverized powder, and the average crystal particle diameter of the ferrite sintered body The average crystal grain size D50 is defined.

  The present invention is not limited to the above embodiment. For example, in the manufacturing method of the ferrite core 12, in order to make the ferrite core 12 into a predetermined shape, a mixture of pulverized powder and binder is formed into a drum shape before the main firing, but the ferrite core 12 has a predetermined shape. For this purpose, the pulverized powder may be formed into a drum shape by subjecting it to main firing and then processing.

  Moreover, in the said embodiment, although the coil component 10 is comprised by the ferrite core 12 and the copper wire 14 with an insulation coating, you may provide the resin mold which surrounds the ferrite core 12 and the copper wire 14 with an insulation coating further. .

  (Examples 1-4 and Comparative Examples 1-6) Each component raw material was weighed so as to have the composition shown in Table 1, and mixed for 5 hours in a ball mill. The raw material mixture thus obtained was calcined in the air at the calcining temperature shown in Table 2 for 2 hours, and then mixed and pulverized in a ball mill for 20 hours.

  After drying the pulverized powder thus obtained and adding 1.0 part by mass of polyvinyl alcohol to 100 parts by mass of the pulverized powder, the resulting mixture was pressure-molded at a pressure of 100 kPa, and the dimensions were 20 mm outer diameter, A toroidal molded body having an inner diameter of 10 mm and a height of 5 mm was obtained. These molded bodies were fired in air at the firing temperature shown in Table 2 for 2 hours to obtain toroidal core samples (ferrite cores) of Examples 1 to 4 and Comparative Examples 1 to 6.

  Each of the toroidal core samples of Examples 1 to 4 and Comparative Examples 1 to 6 was wound with a wire of φ0.35 mm 20 times, and then the inductance value was measured with a Precision LCR meter 4284A manufactured by Hewlett-Packard Company. The initial permeability μi at 4 A / m was determined. The results are shown in Table 1.

Further, with respect to the toroidal core sample used for the measurement of the initial permeability μi, an inductance value is further measured in the range of −40 to 150 ° C., and the relative temperature coefficient αμ _ir of the initial permeability in this temperature range is expressed by the above equation (1). It calculated | required by the type | formula shown in.

ただし、上記式中、Ｔ_１，Ｔ_２はそれぞれ測定の行われた温度を表し、μi_１，μi_２はそれぞれ温度Ｔ_１，Ｔ_２における初透磁率を表す。この数式による初透磁率の算出結果を表１に示す。

However, in the above formula, T ₁ and T ₂ represent the temperatures at which the measurements were made, and μ i ₁ and μ i ₂ represent the initial magnetic permeability at the temperatures T ₁ and T ₂ , respectively. Table 1 shows the calculation results of the initial permeability according to this mathematical formula.

Here, the relative temperature coefficient αμ _ir of the initial permeability is reversed in sign between −40 to 20 ° C. and 20 to 150 ° C., and T1 = −40 ° C. and T2 = 150 ° C. When the relative temperature coefficient αμ _ir of the initial permeability is calculated, it may be calculated as a small value. It is difficult to say that the relative temperature coefficient αμ _ir calculated in this case accurately represents the temperature characteristic of the initial permeability. Therefore, in Table 1, the temperature range is divided into a range of −40 to 20 ° C. and a range of 20 ° C. to 150 ° C., and the relative temperature coefficient αμ _ir of the initial permeability is calculated in each temperature range. .

  Further, the pulverized powder obtained in the process of producing the toroidal core samples of Examples 1 to 4 and Comparative Examples 1 to 6 was observed using a SEM with a visual field of 46 μm × 35 μm (magnification: 5500 times). The average crystal grain size D90 in the particle size distribution with respect to the primary particle size of the pulverized powder was calculated by analyzing the SEM image thus obtained with an image analyzer IP-1000 manufactured by Asahi Kasei. The results are shown in Table 2.

  Further, the toroidal core samples of Examples 1 to 4 and Comparative Examples 1 to 6 were observed using a SEM with a visual field of 85 μm × 64 μm (magnification: 1500 times), and the SEM images observed at this time were image analysis apparatus IP manufactured by Asahi Kasei. The average crystal grain size D50 was calculated by analyzing by -1000. The results are shown in Table 2.

  Furthermore, the density of the sintered body was calculated from the outer diameter, inner diameter, height dimension and weight of the toroidal core sample. The results are shown in Table 2.

  Further, for the trochoidal core samples according to Examples 1 and 3 and Comparative Examples 1 and 2, the relationship between the initial permeability μi and the temperature was examined. The result is shown in FIG.

As is clear from the results shown in Table 1, the toroidal core samples according to Examples 1 to 4 have a relative temperature of initial permeability μi in any of a temperature range of −40 to 20 ° C. and a temperature range of 20 to 150 ° C. The coefficient α μ _ir is in the range of −2 to 2 ppm / ° C., and the toroidal core sample that is a coil component can be properly operated over a wide temperature range of −40 to 150 ° C. and can be used for a wide range of applications. It was.

On the other hand, in the toroidal core samples according to Comparative Examples 1 to 6, the relative temperature coefficient αμ _ir of the initial permeability μi is out of the range of −2 to 2 ppm / ° C. in the temperature range of −40 to 20 ° C. It has been found that the toroidal core sample as a component cannot be properly operated over a wide temperature range of −40 to 150 ° C. and cannot be used for a wide range of applications.

As described above, according to the present invention, the relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C. Thus, it was confirmed that the ferrite sintered body can be obtained, the coil component can be properly operated over a wide temperature range of −40 to 150 ° C., and can be used for a wide range of applications.

It is a perspective view which shows one Embodiment of the coil components of this invention. It is a graph which shows the relationship between the initial permeability (micro | micron | mu) i and temperature about the trochoidal core sample which concerns on Example 1, 3 and Comparative Example 1,2.

  10 ... Coil parts, 12 ... Ferrite core, 14 ... Winding

Claims (3)

And 46.0～49.0Mol% iron oxide calculated as Fe ₂ O _3,
20.0-30.0 mol% zinc oxide in terms of ZnO,
1.0 to 9.0 mol% copper oxide in terms of CuO;
0.1 to 1.0 mol% manganese oxide in terms of Mn ₂ O ₃ ,
Fe ₂ O _3, ZnO, consists of a nickel oxide of the remainder except for CuO and _Mn 2 _{O 3,}
The molar ratio of Fe ₂ O ₃ represented by ZnO / Fe ₂ O ₃ and ZnO is 0.54 to 0.67,
The average crystal grain size D50 is 5 to 15 μm,
The relative temperature coefficient αμ _ir of the initial permeability μi is −2 to 2 ppm / ° C. over the temperature range of −40 to 20 ° C. and the temperature range of 20 to 150 ° C.,
A ferrite sintered body characterized by that. And 46.0～49.0Mol% iron oxide calculated as Fe ₂ O _3,
20.0-30.0 mol% zinc oxide in terms of ZnO,
1.0 to 9.0 mol% copper oxide in terms of CuO;
0.1 to 1.0 mol% manganese oxide in terms of Mn ₂ O ₃ ,
The remaining nickel oxide excluding Fe ₂ O ₃ , ZnO, CuO and Mn ₂ O ₃ ,
And calcining steps molar ratio of _Fe 2 _{O 3} and ZnO, represented by ZnO / _Fe 2 _{O 3} to obtain a raw material mixture calcined to pre-sintered product is from 0.54 to 0.67,
A pulverizing step of pulverizing the calcined product to obtain a pulverized powder;
Molding the pulverized powder to obtain a molded body;
Including a main firing step of subjecting the molded body to main firing to obtain a ferrite sintered body,
In the pulverization step, the calcined product is pulverized so that the average crystal particle size D90 in the particle size distribution for the primary particle size of the pulverized powder is 5 μm or less,
In the main firing step, the pulverized powder is fired so that the average grain size D50 in the ferrite sintered body is 5 to 15 μm, whereby the relative temperature coefficient αμ _ir of the initial magnetic permeability μi is −40 to 20 A method for producing a ferrite sintered body characterized in that a ferrite sintered body having a temperature range of -2 to 2 ppm / ° C is obtained over a temperature range of ° C and a temperature range of 20 to 150 ° C. A coil component comprising the ferrite sintered body according to claim 1.

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