JP2011100802A - Magnetic material and coil component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic material capable of acquiring high permeability in a high frequency domain and which has a high Q value, and to provide a coil component having a core member consisting of the magnetic material and which has a high Q value in a frequency domain of 150-250 MHz where the usual spinel type oxide material can not be used because of a low Q value. <P>SOLUTION: In a magnetic material represented by a composition formula (Ba<SB>3-x+y</SB>Ca<SB>x</SB>)Co<SB>2+z</SB>Fe<SB>24</SB>O<SB>41-δ</SB>, x, y and z (mol ratios) satisfy 0.3≤x≤0.8, 0.02≤y≤0.4, and -0.3≤z≤0.3, respectively. A core member 2 consisting of the magnetic material is used to obtain a coil component 1. In more particular, in the core member 2 including a core 5 and a flange 6 formed at an axial directional end of the core 5, a coil 4 is wound around the core 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic material and a coil component using the same, and more particularly to a hexagonal ferrite magnetic material and a coil component having a core member formed using the same.

In recent years, with the increase in the frequency of electronic devices, the component parts are also required to cope with the higher frequency.
Among such components, a coil component including a core member made of an oxide magnetic material has been strongly required to cope with high frequency.

By the way, as a material constituting the core member of the coil component, conventionally, a magnetic material or a dielectric is used. As the magnetic material, spinel oxide magnetic materials are widely used.
However, in the case of a spinel type oxide magnetic material, there is a problem in that the magnetic permeability rapidly decreases when the frequency becomes higher than a certain level. Particularly in the case of nickel ferrite, the real part (μ ′) of the magnetic permeability decreases from the vicinity where the frequency exceeds 300 MHz, and the imaginary part (μ ″) of the magnetic permeability increases from the vicinity where the frequency exceeds 150 MHz, Since the cross-point frequency is about 600 MHz, nickel ferrite cannot be used as a core member of a coil component used in a high frequency region exceeding 150 MHz when high Q is required.

Therefore, dielectric ceramics are widely used as core members in coil components used in the high frequency region. Here, since the dielectric ceramic is a non-magnetic material, in order to obtain the necessary inductance in the coil component, the core member is enlarged or the number of windings arranged around the core member is increased. It will be necessary.
However, when the core member is enlarged, there is a problem that it is difficult to reduce the size of the coil component as a product. When the number of windings around the core member is increased, the winding resistance increases. There is a problem that the Q of the coil is lowered and the sensitivity of the circuit is lowered.

  Therefore, a material that is a magnetic material and does not lower the permeability (real part) μ ′ in a high frequency region has been desired. As a material that meets such a demand, Z-type hexagonal ferrite has been studied, Proposals have been made.

For example, from the above viewpoint, in the material represented by the general formula Ba ₃ Co ₂ Fe ₂₄ O ₄₁ , a ferromagnetic material in which 1/3 or less of Ba is substituted with Sr, Ca, Pb has been proposed ( (See Patent Document 1).

Further, in terms of oxide, Fe ₂ O ₃ is 68 to 73 mol%, MO (M is at least one of Ba, Sr, and Pb) is 15 to 22 mol%, CoO is 9 to 13 mol%, and SiO ₂ is 0.04. A Z-type hexagonal oxide magnetic material containing ˜1.0 mol% and CaO in a range of 0.04 to 1.0 mol% has been proposed (see Patent Document 2).

_{Further, BaO: 10~30mol%, Fe 2} O 3: 56~65mol%, MeO: 8~25mpl% ( where, Me is Zn, Co, Ni, Cu, at least one trivalent metal ion Mn) of A soft magnetic hexagonal ferrite containing 0.05 to 0.5 wt% of SiO ₂ and 0.05 to 0.5 wt% of CaO with respect to the main component has been proposed (see Patent Document 3). .

  However, in any of these magnetic materials, the permeability (real part) μ ′ and the Q value (= μ ′ / μ ″) in the high-frequency region, particularly in the high-frequency region of 250 MHz or higher, do not necessarily satisfy the requirements sufficiently. In fact, there is a need for a magnetic material having a high Q value with little decrease in permeability (real part) μ ′ in a high frequency region.

Japanese Patent Publication No.33-736 JP-A-9-110432 JP-A-9-129433

  The present invention solves the above-described problems, and can obtain a high magnetic permeability in a high frequency region, and further includes a magnetic material having a high Q value, and a normal spinel type including a core member made of the magnetic material An object of the present invention is to provide a coil component having a high Q value even in a frequency range of 150 MHz to 250 MHz, in which an oxide material has a low Q value and cannot be used.

In order to solve the above problems, the magnetic material is
Expressed by a composition formula _{(Ba 3-x + y Ca} x) Co 2 + z Fe 24 O 41-δ, wherein x, y, z represents the molar ratio, respectively, 0.3 ≦ x ≦ 0.8 0.02 ≦ y ≦ 0.4 and −0.3 ≦ z ≦ 0.3.

  A coil component of the present invention is characterized by including a core member made of the magnetic material according to claim 1.

  In the coil component of the present invention, the core member includes a core portion and a flange portion formed at an end portion in the axial direction of the core portion, and the winding is wound around the core portion. It is characterized by being turned.

Magnetic material of the present invention are represented by a composition formula _{(Ba 3-x + y Ca} x) Co 2 + z Fe 24 O 41-δ, x, y, z is a molar ratio, respectively, 0.3 ≦ Since x ≦ 0.8, 0.02 ≦ y ≦ 0.4, and −0.3 ≦ z ≦ 0.3, the magnetic permeability (real part) μ ′ is reduced in the high frequency region. Therefore, it is possible to provide a magnetic material having a high Q value.

  In addition, since the coil component of the present invention includes the core member made of the above-described magnetic material of the present invention, the normal spinel type oxide material has a low Q value and cannot be used. Even in the frequency region, a coil component having a high Q value can be provided.

  Further, as in the coil component of the present invention, the core member includes a core portion and a flange portion formed at an end portion in the axial direction, and a winding is wound around the core portion. This makes it possible to provide a wire-wound coil component having a high Q value even in the frequency range of 150 MHz to 250 MHz.

It is a perspective view which shows the coil components which have the structure by which the coil | winding was wound by the core part of the core member formed using the magnetic material of this invention.

  Embodiments of the present invention will be described below to describe the features of the present invention in more detail.

BaCO ₃ , CaCO ₃ , Co ₃ O ₄ , and Fe ₂ O ₃ raw powders having a specific surface area in the range of ² to 20 m ² / g are represented by a composition formula (Ba _{3−x + y} Ca _x ) Co _{2 + z} Fe. ₂₄ O _41-δ was weighed so as to have the molar ratio (ferrite composition) shown in Table 1. Then, the weighed raw material powders were mixed with a ball mill and then calcined in the atmosphere at a temperature of 900 to 1300 ° C. for 10 hours to obtain a primary calcined powder.

  These primary calcined powders are pulverized by a ball mill or the like and then calcined in the atmosphere at a temperature of 900 to 1300 ° C. for 10 hours to obtain secondary calcined powders (calcined powders that have undergone a double calcining step). Got.

  The secondary calcined powder was pulverized with a ball mill or the like, and then PVA was added as a binder and spray granulated to obtain a granulated body. Then, after this granulated body was press-molded, the molded body was fired at 1000 to 1300 ° C. to obtain a sintered body.

[Measurement of permeability, cross point and Q value of each sample]
Each sintered body (sample) obtained as described above is formed into a ring shape having an outer diameter of 10 mm, an inner diameter of 6 mm, and a thickness of 2 mm as shown in the appendix of JIS standard C-2560-2. processed. And about the ring-shaped sintered compact (sample) obtained in this way, permeability μ ′ (real part), μ ″ (imaginary part), and cross-point frequency (frequency at which μ ′ = μ ″) are obtained, It measured according to JIS standard C-2560-2. The magnetic permeability μ ′ (real part) and μ ″ (imaginary part) of each sample was measured using an impedance analyzer (model number HP4291A) manufactured by Agilent Technologies.

Table 1 shows the measurement results of the magnetic permeability μ ′ and the crosspoint frequency (frequency at which μ ′ = μ ″) at frequencies of 250, 500 MHz, and 1 GHz.
Further, the Q value (= μ ′ / μ ″) was determined from the values of the magnetic permeability μ ′ (real part) and μ ″ (imaginary part) of each sample. The results are also shown in Table 1.

[Measurement of resistivity]
After the granulated body was press-molded, a sintered body obtained by firing the molded body at 1000 to 1300 ° C. was processed into a disk shape to prepare a sample for measuring specific resistance.
And the In-Ga electrode was formed in the end surface of each produced sample, the insulation resistance was measured with the insulation resistance meter, and the specific resistance was calculated | required from this insulation resistance and the external dimension of the sample. The specific resistance value of each sample is also shown in Table 1.

  In Table 1, samples with a sample number marked with * are samples that do not have the requirements of the present invention.

From the results shown in Table 1, in the _{(Ba 3-x + y Ca} x) Co 2 + z Fe 24 O 41-δ, increasing the substitution amount of Ca to (x), μ ', and the cross point frequency monotonously It was confirmed that the Q value and the specific resistance showed a maximum when the substitution amount was around 0.5 mol (x = 0.5) (for example, samples Nos. 7 to 12).

  When x is less than 0.3 (for example, samples of sample numbers 7 and 8), the value of μ ′ at 250 MHz is 10 or more, but the Q value at 250 MHz is less than 15 (for the sample of sample number 7) Q = 10 and Q = 12 for the sample of sample number 8), and the result was confirmed to be not preferable.

Further, when the amount of substitution (x) of Ca exceeds 0.8, even if the values of y and z satisfy the requirements of the present invention (sample No. 12), μ ′ at 250 MHz is 5 and 7 It was confirmed that it is not preferable because it is less than.
From this result, it can be seen that the substitution amount (x) of Ca is preferably in the range of 0.3 to 0.8.

  In addition, when the value of y representing the deviation of the total number of moles of Ba and Ca is 0, that is, in the case of a stoichiometric composition (samples of sample numbers 1 to 6), x is changed from 0 to 1.0. However, it was confirmed that μ ′ at 250 MHz cannot satisfy 7 or more and Q value of 15 or more simultaneously.

  In contrast, when y = 0.1, that is, when the total number of moles of Ba and Ca is less than the stoichiometric composition (samples 7 to 12), compared to when y = 0, It was confirmed that μ ′ and the Q value were increased.

It was also confirmed that μ ′ and the Q value were higher in the case of samples Nos. 10 and 14 to 17 with y = 0.02 to 0.4 than when y = 0.
However, it was confirmed that when the value of y was increased to 0.5 (sample No. 13), μ ′ was less than 7 and the Q value was less than 15, which was not preferable.
From this result, it can be seen that the value of y representing the deviation in the total number of moles of Ba and Ca is preferably in the range of 0.02 to 0.4.

  Furthermore, it was confirmed that the value of z representing the deviation in the number of moles of Co is preferably in the range of -0.3 to 0.3. If the value of z exceeds this range, μ ′ is less than 7 and the Q value is less than 15 (samples Nos. 18 and 21).

  As described above, according to the present invention, a magnetic material having μ ′ at 250 MHz of 7 or more and a Q value of 15 or more can be obtained. Therefore, by using the magnetic material of the present invention, it is possible to provide a coil component having a high Q value even in a frequency range of 150 MHz to 250 MHz that cannot be used with a spinel oxide material having a low Q value.

  In addition, it is possible to obtain a magnetic material having a crosspoint frequency of 1 GHz or more. Since such a magnetic material has a larger real part than the imaginary part of the magnetic permeability up to 1 GHz, it can be used as a coil component. Possible magnetic materials can be provided. That is, although the Q value is naturally low at 1 GHz, it functions as a coil up to 1 GHz. Therefore, it can be used as a coil in applications where the Q value does not need to be so high. Contrary to the above, when the cross-point frequency is low, the imaginary part of the magnetic permeability becomes large at the frequency exceeding the cross-point frequency, and the resistance R becomes a main element, and the function as a coil is expected. become unable.

Moreover, when configuring the coil component, in order to improve the reliability of the electrode part, an electrolytic plating process is performed so as to cover the electrode, but if the specific resistance of the magnetic material is low, the electrode part is changed to the magnetic material part. Although the elongation of the plating occurs, the magnetic material of the present invention has a high specific resistance of 10 ⁶ Ωcm or more, so that the elongation of the plating can be prevented.

In addition, since the specific resistance is as high as 10 ⁶ Ωcm or more, when the coil component is configured, the eddy current loss is small and the Q value of the coil component can be increased.

Specifically, the magnetic material having the above characteristics can be applied to, for example, a coil component as shown in FIG.
As shown in FIG. 1, the coil component 1 is a wound coil, and includes a core member 2, an electrode portion 3, and a winding 4. The core member 2 includes a core portion 5 and two (a pair of) flange portions 6 formed at both ends in the axial direction of the core portion 5.

  The core part 5 has a rectangular parallelepiped shape in which, for example, the shape of the cross section perpendicular to the axial direction is a horizontally long rectangle, and the shape of the vertical cross section in a direction balanced in the axial direction is a horizontally long rectangle. .

  The pair of flange portions 6 have symmetrical shapes, and the cross-sectional shape orthogonal to the axial direction is a rectangle having a larger dimension than the cross-section of the winding core portion 5 in the same direction, and the axial direction is thick. It has a thin, substantially rectangular parallelepiped shape. A curved surface portion 70 is formed at a boundary portion between the pair of flange portions 6 and the lower core portion 5 so as to be formed of a curved surface at the stepped portion 7. Furthermore, the electrode portion 3 is provided on one surface (the lower surface in FIG. 1) of the outer peripheral surface of the flange portion 6.

  The winding 4 is wound around the winding core portion 5 that is an area sandwiched between the pair of flange portions 6, and the lead-out portion 41 that is the end of the winding 4 is soldered, for example. In such a manner, it is connected to the electrode portion 3 disposed on the lower surface of the flange portion 6.

  By producing the winding coil as described above using the magnetic material of the present invention, it is possible to provide a winding coil having a high Q value even in the frequency range of 150 MHz to 250 MHz.

  In addition, the present invention is not limited to the above-described examples in other respects. Specific conditions such as the type of raw material powder used in the production process of the magnetic material of the present invention, firing conditions in the production process, With respect to the specific structure of the coil component using the magnetic material of the present invention as the core member, various applications and modifications can be made within the scope of the invention.

1 Coil parts (winding coil)
2 Core member 3 Electrode part 4 Winding 5 Winding core part 6 Groove part 7 Step part between collar part and core part 41 Winding lead-out part 70 Curved surface part

Claims (3)

Expressed by a composition formula _{(Ba 3-x + y Ca} x) Co 2 + z Fe 24 O 41-δ, wherein x, y, z represents the molar ratio, respectively, 0.3 ≦ x ≦ 0.8 0.02 ≦ y ≦ 0.4 and −0.3 ≦ z ≦ 0.3.   A coil component comprising a core member made of the magnetic material according to claim 1. The core member includes a core part and a flange part formed at an axial end of the core part,
The coil component according to claim 2, wherein a winding is wound around the winding core.

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