JP2004172396A - Ferrite material and inductance element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide Ni-Zn system or Ni-Zn-Cu system ferrite materials and inductance elements capable of extremely reducing the change of inductance values(L values) of coil type inductance elements and lamination type inductance elements at the time of DC superimpose, and easily reducing the size and height of the elements without increasing man-hours or the number of parts by executing the composition improvement of the ferrite materials themselves. <P>SOLUTION: The specific quantities of ZrO<SB>2</SB>and SiO<SB>2</SB>are simultaneously added to Ni-Zn system or Ni-Zn-Cu system ferrite materials so that the change of the permeability of the ferrite materials equivalent to the L values of inductance elements at the time of DC superimpose can be reduced, and that the size and height reduction of the elements can be realized while the structural change of the elements can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

【００４０】
実施例２
表２に示す実施例９、比較例５及び比較例６のＮｉ−Ｚｎ−Ｃｕ系フェライト材料を用いて、図２に示す積層型インダクタンス素子を作製した。実施例９は全厚みに対するコイル層厚みの比率を４５％とし、比較例６は６５％とした。
【００４１】
また、比較例５は、実施例９とコイル層厚みは同様であるが、組成が本発明の範囲外である。得られた積層型インダクタンス素子のＩｄｃ＝１０ｍＡの直流電流を重畳した時の透磁率の変化を測定した。その測定結果を表２に示す。
【００４２】
表２から明らかなように、この発明によるＮｉ−Ｚｎ−Ｃｕ系フェライト材料を積層型インダクタンス素子に適用した場合においても、比較例による同系フェライト材料に比べて透磁率の変化が少ないことが分かる。
【００４３】
【表２】

【００４４】
【発明の効果】
この発明によるＮｉ−Ｚｎ系またはＮｉ−Ｚｎ−Ｃｕ系フェライト材料は、特定量のＺｒＯ_２ 、ＳｉＯ_２ を同時に添加することにより、直流重畳時の透磁率の変化が少なくなり、この発明のフェライト材料をインダクタンス素子に用いることにより、直流重畳時のインダクタンス値（Ｌ値）の変化を極力少なくすることができ、大電流にも対応でき、かつ、安定した性能を発揮するインダクタンス素子を得ることができる。
【００４５】
また、この発明によるインダクタンス素子は、構造的な改善が不要となるため、工数の削減や部品点数の削減を図ることができ、安価にして提供することが可能になるとともに、さらなる小型化、低背化を図ることが可能となる。また、この発明の積層型インダクタンス素子は、コイル層の厚みを全体の厚みの７〜６０％の厚みに減少させることにより、ヨーク層の厚みを増加し、高いインダクタンス値を得ることができる。
【００４６】
さらに、この発明の積層型インダクタンス素子は、磁気回路的に閉磁路構成であり、特にヨーク層の厚みを増加した上記インダクタンス素子では、漏洩磁束はほとんど発生しない。従って、インダクタンス素子からの漏洩磁束が他の機器に与える影響が懸念される用途、例えばノート型パーソナルコンピュータ、携帯電話、デジタルビデオカメラ、デジタルスチルカメラ、車載用ＣＣＤカメラ等のスイッチング電源回路及びインバータ電源回路として最適である。
【図面の簡単な説明】
【図１】巻き線型インダクタンス素子の構成の概略を示す分解斜視説明図である。
【図２】Ａは積層型インダクタンス素子の構成の概略を示す分解斜視説明図であり、Ｂは積層した状態でＡ図のｂ−ｂ線位置の断面説明図である。
【図３】巻き線型インダクタンス素子の構成の概略を示す断面説明図である。
【図４】巻き線型インダクタンス素子の他の構成の概略を示す断面説明図である。
【符号の説明】
１ Ｅ型コア
２ コイル
３ Ｉ型コア
４ 補助端子
５ 積層型インダクタンス素子
６ コイルパターン
７ グリーンシート
８ コイル層
９，１０ ヨーク層
１１，１２ シート状磁性体
１３ 磁気ギャップTECHNICAL FIELD OF THE INVENTION
[0001]
The present invention relates to a Ni—Zn or Ni—Zn—Cu ferrite material for an inductance element used in a switching power supply circuit and an inverter power supply circuit of various electronic devices such as a computer and a mobile phone.
[0002]
[Prior art]
2. Description of the Related Art In recent years, miniaturization of notebook personal computers, mobile phones, and the like has progressed, and miniaturization and reduction in height of an inductance element used in a power supply circuit thereof have been required, and improvement in inductance value (L value) and inductance value have been required. There is a demand for an improvement in DC superimposition characteristics such as minimizing a change in (L value).
[0003]
As the inductance element, a wound-type inductance element is widely used. For example, as shown in FIG. 1, a winding type inductance element is a ferrite in which a cylindrical central leg 1c is provided upright at the center of a concave portion 1b surrounded by outer legs 1a provided on a pair of opposed sides. An E-type core 1 made of a material, a winding 2 (an edgewise coil in the figure), and an I-type core 3 made of a ferrite material are provided. The winding 2 is accommodated in a concave portion 1b of the E-type core. The mold core 3 is formed by closing the recess 1b of the E-shaped core. Reference numeral 4 in the figure denotes an auxiliary terminal for obtaining a mounting strength when the inductance element is mounted on the printed circuit board.
[0004]
As the core material of the wound-type inductance element having the above configuration, a Ni—Zn-based ferrite material is often used. The wound-type inductance element has an advantage that it can be manufactured at low cost.
[0005]
As the inductance element, a laminated inductance element can be used. For example, as shown in FIGS. 2A and 2B, the laminated inductance element 5 includes a coil layer 8 formed by laminating sheet-like magnetic materials such as a green sheet 7 on which a coil pattern 6 is formed, and a magnetic layer sandwiching the coil layer 8. And a body layer (hereinafter, referred to as a yoke layer) 9, 10. The yoke layers 9 and 10 can be formed by laminating sheet-like magnetic bodies 11 and 12 above and below the coil layer 8, respectively.
[0006]
A Ni—Zn—Cu ferrite material that can be fired at a low temperature is used for the magnetic material of the multilayer inductance element. By reducing the number of stacked green sheets, the stacked inductance element can be reduced in size and height as a whole.
[0007]
Many proposals have been made to add various trace components to ferrite materials used in the above-mentioned winding type inductance elements and multilayer inductance elements for the purpose of improving sinterability and magnetic properties.
[0008]
For example, in Japanese Patent No. 3147496, by simultaneously adding Co ₃ O ₄ , Bi ₂ O ₃ , SiO ₂ , and SnO ₂ to a Ni—Zn—Cu-based ferrite material, the shrinkage stress of the resin in the resin molding process is reduced. There has been proposed a highly reliable ferrite core which is hardly affected and whose L value and Q value hardly change before and after the resin molding process.
[0009]
[Problems to be solved by the invention]
However, in the above-mentioned patented invention, although the solution of the problem of the resin molding process and the improvement of the magnetic characteristics have been achieved, no consideration is given to the improvement of the DC superimposition characteristics.
[0010]
As a means for improving the DC superimposition characteristic, in the winding type inductance element, as shown in FIG. 3, the center leg 1c of the E-shaped core 1 is slightly shorter than the outer leg 1a, so that the center leg 1c and the I-shaped core 3 Some proposals have been made to improve the DC superimposition characteristics by means such as forming a magnetic gap 13 in a magnetic path between them or interposing a spacer between the center leg 1c and the I-shaped core 3.
[0011]
Further, also in a multilayer inductance element, a proposal has been made to improve a DC superposition characteristic by interposing a nonmagnetic material layer in a yoke layer.
[0012]
However, the structural improvement as described above involves an increase in man-hours and an increase in the number of parts, so that an increase in cost is unavoidable. Further, since the structure is complicated, a reduction in size and height is hindered. Will be.
[0013]
As described above, the improvement of the DC superimposition characteristics has been proposed by a structural improvement, but the improvement of the material (composition) by an additive element or the like has not been proposed. At present, no proposal has been made to minimize the change in the value (L value).
[0014]
According to the present invention, in the present situation of the wound inductance element and the laminated inductance element, the DC superimposition characteristic of the element, particularly, the change of the inductance value (L value) at the time of DC superposition is improved by the compositional improvement of the ferrite material itself. A Ni-Zn-based or Ni-Zn-Cu-based ferrite material and an inductance element which can be reduced as much as possible and can easily realize the miniaturization and reduction of the height of the element without increasing the number of steps and parts. The purpose is to provide it at low cost.
[0015]
[Means for Solving the Problems]
In order to improve the DC bias characteristics by improving the composition of the ferrite material, and in particular to minimize the change in the inductance value (L value) during DC bias, the inventors have proposed a Ni—Zn-based or Ni—Zn— As a result of various studies on the composition of the Cu-based ferrite material, a specific amount of ZrO ₂ or SiO ₂ was simultaneously added to a Ni—Zn-based or Ni—Zn—Cu-based ferrite material to obtain a ferrite equivalent to the L value of the inductance element. The inventors have found that the change in the magnetic permeability of the material during DC superimposition is small and the object can be achieved, and thus completed the present invention.
[0016]
That is, the ferrite material according to the first invention is characterized in that a so-called Ni—Zn ferrite material contains 0.01 to 1.0 wt% of ZrO _{2 and} 1.0 wt% or less of SiO ₂ (not including 0). And further comprising, as necessary, 1.5 wt% or less of Bi ₂ O ₃ and 1.0 wt% or less of SnO ₂ .
[0017]
Further, the ferrite material according to the second invention is the so-called Ni-Zn-Cu ferrite _material, ZrO 2 0.05 to _0.5%, (not including 0) SiO 2 1.0 wt% or less, _Bi 2 O ₃ 0.5 to 1.5% or _less, characterized in that it contains a SnO 2 0.1-1.0% or less.
[0018]
The ferrite materials according to the first and second inventions can each contain Co ₃ O ₄ at 0.5 wt% or less. Further, any of the ferrite materials according to the present invention can be characterized in that the content of Fe ₂ O ₃ is 50 mol% or less.
[0019]
An inductance element according to the present invention includes a core made of the ferrite material having the above-described configuration to which at least specific amounts of ZrO ₂ and SiO ₂ are simultaneously added.
[0020]
A laminated inductance element according to the present invention is a laminated inductance element including a coil layer formed by laminating sheet-shaped magnetic bodies on which a coil pattern is formed, and a magnetic layer sandwiching the coil layer, wherein the sheet-shaped magnetic body is characterized by comprising the Ni-Zn-Cu ferrite material containing a specific amount of _{ZrO 2, SiO 2, Bi 2} O 3, SnO 2. Still further, the laminated inductance element is characterized in that the thickness of the coil layer is 7 to 60% of the total thickness.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
In the ferrite material of the present invention, by simultaneously adding a specific amount of ZrO ₂ and SiO ₂ , a change in the magnetic permeability at the time of direct current superposition is reduced, and by using the ferrite material for an inductance element, the inductance at the time of direct current superposition is reduced. A change in the value (L value) can be minimized, an inductance element that can cope with a large current and exhibits stable performance can be obtained.
[0022]
In addition, the inductance element according to the present invention does not require structural improvement, so that the number of steps and the number of parts can be reduced. The height can be reduced.
[0023]
Further, in the multilayer inductance element of the present invention, the thickness of the yoke layer can be increased by reducing the thickness of the coil layer to a thickness of 7 to 60% of the entire thickness, and a high inductance value can be obtained.
[0024]
Furthermore, the laminated inductance element of the present invention has a closed magnetic circuit configuration in the form of a porcelain circuit. In particular, in the above-described inductance element in which the thickness of the yoke layer is increased, almost no leakage magnetic flux is generated. It is optimally used as a switching power supply circuit and an inverter power supply circuit for applications that may affect other devices, for example, notebook personal computers, mobile phones, digital video cameras, digital still cameras, in-vehicle CCD cameras, and the like.
[0025]
Hereinafter, the reasons for limiting the composition of the ferrite material according to the present invention will be described.
ZrO ₂ is an essential element and has the effect of improving the DC bias characteristics. The preferred range is 0.01 wt% to 1.0 wt% for Ni-Zn based ferrite material, and 0.05 wt% to 0.5 wt% for Ni-Zn-Cu based. In any of the systems, if the value is less than the lower limit, the effect of improving the DC superimposition characteristic is small, and if the value exceeds the upper limit, the sinterability and magnetic properties are undesirably deteriorated.
[0026]
SiO ₂ is an essential element and has an effect of reducing a change in magnetic permeability of a ferrite material at the time of direct current superposition. In both cases of Ni-Zn-based and Ni-Zn-Cu-based, addition of 1.0 wt% or less (excluding 0) is preferable, and exceeding 1.0 wt% is not preferable because sinterability is reduced.
[0027]
The present invention is characterized in that the above-mentioned specific amounts of ZrO ₂ and SiO ₂ are simultaneously added, and thereby excellent DC bias characteristics can be exhibited. The addition of the above preferable range is possible during any of the manufacturing steps up to sintering, such as the compounding step and the pulverizing step.
[0028]
Bi ₂ O ₃ is added to improve sinterability, but may be added to a Ni—Zn-based ferrite material and not used when the material is used for a wound inductance element. In the case of adding, if it exceeds 1.5 wt%, the magnetic properties deteriorate, which is not preferable.
[0029]
On the other hand, when Bi ₂ O ₃ is added to a Ni—Zn—Cu system, it is preferable to add 0.5 wt% to 1.5 wt% in order to improve sinterability. If it is less than 0.5 wt%, the effect of addition is small, and if it exceeds 1.5 wt%, the magnetic properties deteriorate, which is not preferable.
[0030]
SnO ₂ is added to improve temperature characteristics and sinterability. When desired temperature characteristics and sinterability are obtained by the main component composition (NiO, ZnO, CuO, Fe ₂ O ₃ ), It is not necessary to add it. When added, the content is preferably 1.0% by weight or less, and if it exceeds 1.0% by weight, the magnetic permeability is undesirably reduced. In the case of a Ni—Zn—Cu ferrite material for a multilayer inductance element, it is preferable to add 0.1 to 1.0 wt%.
[0031]
Co ₃ O ₄ is added for the purpose of improving temperature characteristics and the like. If the content exceeds 0.5 wt%, the magnetic properties deteriorate, so the addition at 0.5 wt% or less is preferable.
[0032]
Which is the main component of the ferrite material of the present invention, NiO, ZnO, CuO, the content of _Fe 2 _{O 3} is, NiO 5.0~40.0mol%, ZnO 0~35.0mol% , CuO 0~20mol% ( However, 3.0～15.0Mol% in the case of the Ni-Zn-Cu-based), the balance _Fe 2 _{O 3} is preferred. Particularly preferably, 10.0 to 30.0 mol% of NiO, 2 to 30.0 mol% of ZnO, 0 to 15 mol% of CuO (however, in the case of Ni-Zn-Cu system, 3.0 to 15.0 mol%), and the balance Fe ₂ O ₃ .
[0033]
In the ferrite material of the present invention, the content of Fe ₂ O ₃ is preferably 50.0 mol% or less, and more preferably 45.0 to 50.0 mol%.
[0034]
The ferrite material according to the present invention having the above-described composition can be applied to a wound inductance element as shown in FIG. 1 or a laminated inductance element as shown in FIG.
[0035]
In particular, when the ferrite material according to the present invention is applied to a multilayer inductance element as shown in FIG. 2, the thickness of the yoke layer is reduced by reducing the thickness of the coil layer to 7 to 60% of the total thickness. It is possible to obtain a higher inductance value.
[0036]
【Example】
Example 1
Each of the steps of compounding, calcining, pulverizing, molding and sintering was carried out so as to have the compositions of Examples 1 to 8 and Comparative Examples 1 to 4 shown in Table 1 by performing Ni-Zn-Cu and Ni-Zn. A ferrite material was prepared.
[0037]
The obtained ring-shaped ferrite material having a diameter of 14 mm was wound with 15 turns, and a change in magnetic permeability when a DC current of Idc = 0.5 A was superimposed was measured. Table 1 shows the measurement results.
[0038]
As is clear from Table 1, the ferrite materials according to the present invention shown in Examples 1 to 8 show less change in magnetic permeability than the ferrite materials according to the comparative examples.
[0039]
[Table 1]

[0040]
Example 2
Using the Ni—Zn—Cu-based ferrite materials of Example 9, Comparative Example 5, and Comparative Example 6 shown in Table 2, the multilayer inductance element shown in FIG. 2 was produced. In Example 9, the ratio of the coil layer thickness to the total thickness was 45%, and in Comparative Example 6, the ratio was 65%.
[0041]
Comparative Example 5 has the same coil layer thickness as Example 9, but the composition is out of the range of the present invention. The change of the magnetic permeability of the obtained laminated inductance element when a DC current of Idc = 10 mA was superimposed was measured. Table 2 shows the measurement results.
[0042]
As is clear from Table 2, even when the Ni—Zn—Cu-based ferrite material according to the present invention is applied to the laminated inductance element, the change in the magnetic permeability is smaller than that of the same type ferrite material according to the comparative example.
[0043]
[Table 2]

[0044]
【The invention's effect】
The Ni—Zn-based or Ni—Zn—Cu-based ferrite material according to the present invention, by adding a specific amount of ZrO ₂ and SiO ₂ at the same time, reduces the change in the magnetic permeability at the time of direct current superposition. Is used as an inductance element, a change in inductance value (L value) at the time of DC superposition can be minimized, and an inductance element that can cope with a large current and exhibit stable performance can be obtained. .
[0045]
Further, since the inductance element according to the present invention does not require structural improvement, the number of steps and the number of parts can be reduced, and it can be provided at a low cost. It becomes possible to achieve a tall. In the multilayer inductance element of the present invention, the thickness of the yoke layer can be increased by reducing the thickness of the coil layer to a thickness of 7 to 60% of the entire thickness, and a high inductance value can be obtained.
[0046]
Furthermore, the laminated inductance element of the present invention has a closed magnetic circuit configuration in terms of a magnetic circuit. In particular, in the above-described inductance element in which the thickness of the yoke layer is increased, almost no leakage magnetic flux is generated. Therefore, applications in which the leakage flux from the inductance element may affect other devices, for example, switching power supply circuits and inverter power supplies for notebook personal computers, mobile phones, digital video cameras, digital still cameras, in-vehicle CCD cameras, etc. Most suitable as a circuit.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view schematically showing a configuration of a wound inductance element.
FIG. 2A is an exploded perspective view schematically illustrating the configuration of a multilayer inductance element, and FIG. 2B is a cross-sectional view taken along the line bb in FIG.
FIG. 3 is an explanatory sectional view schematically showing a configuration of a wound inductance element.
FIG. 4 is an explanatory cross-sectional view schematically illustrating another configuration of the wound inductance element.
[Explanation of symbols]
Reference Signs List 1 E-type core 2 Coil 3 I-type core 4 Auxiliary terminal 5 Laminated inductance element 6 Coil pattern 7 Green sheet 8 Coil layer 9, 10 Yoke layer 11, 12 Sheet magnetic body 13 Magnetic gap

Claims (7)

ZrO ₂ 0.01 wt% to 1.0 wt%, SiO ₂ 1.0 wt% or less (excluding 0), Bi ₂ O ₃ 0 to 1.5 wt% or less, SnO ₂ 0 to 1.0 wt% or less A Ni-Zn ferrite material characterized by the above-mentioned. ZrO ₂ 0.05 wt% to 0.5 wt%, SiO ₂ 1.0 wt% or less (excluding 0), Bi ₂ O ₃ 0.5 wt% to 1.5 wt% or less, SnO ₂ 0.1 wt% to 1. A Ni-Zn-Cu-based ferrite material containing 0 wt% or less. _3. The ferrite material according to claim 1, wherein the ferrite material contains 0.5 wt% or less of Co ₃ O _{4. 4} . Ferrite material according to any one of claims 1 to 3, the content of Fe ₂ O ₃ is equal to or less than 50 mol%. An inductance element comprising a core made of the ferrite material according to claim 1. A laminated inductance element including a coil layer formed by laminating sheet-shaped magnetic bodies having a coil pattern formed thereon, and a magnetic layer sandwiching the coil layer, wherein the sheet-shaped magnetic body is made of the ferrite material according to claim 2. A multilayer inductance element characterized by the above-mentioned. The multilayer inductance element according to claim 6, wherein the thickness of the coil layer is 7 to 60% of the total thickness.

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