JP2006080166A - Dust core - Google Patents
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本発明は、スイッチング電源などに搭載されるトランスやリアクトルなどの磁気部品に用いる圧粉磁心に関する。 The present invention relates to a dust core used for a magnetic component such as a transformer or a reactor mounted on a switching power supply or the like.
近年、各種電子機器は小型・軽量化されてきており、なおかつ、低消費電力化が求められている。これに伴い、電子機器に搭載される電源として高効率かつ小型のスイッチング電源に対する要求が高まっている。特にノート型パソコンや携帯電話等の小型情報機器、薄型ＣＲＴ、テレビのフラットパネルディスプレイ等に用いられるスイッチング電源では、小型・薄型化が強く求められている。
しかし、従来のスイッチング電源では、その主要な構成部品であるトランスやリアクトルなどの磁気部品が大きな体積を占めており、スイッチング電源を小型・薄型化するためには、これら磁気部品の体積を縮小することが必要不可欠となっていた。
In recent years, various electronic devices have been reduced in size and weight, and low power consumption has been demanded. In connection with this, the request | requirement with respect to a highly efficient and small switching power supply as a power supply mounted in an electronic device is increasing. In particular, switching power supplies used for small information devices such as notebook computers and mobile phones, thin CRTs, flat panel displays for televisions, and the like are strongly required to be small and thin.
However, in conventional switching power supplies, magnetic components such as transformers and reactors, which are the main components, occupy a large volume. To reduce the size and thickness of switching power supplies, the volume of these magnetic components is reduced. It was essential.
従来、このようなスイッチング電源に使用されているトランス又はリアクトルなどの磁気部品の磁心材料としては、センダストやパーマロイなどの金属磁性材料や、フェライトなどの酸化物磁性材料が使用されていた。 Conventionally, metal magnetic materials such as sendust and permalloy, and oxide magnetic materials such as ferrite have been used as magnetic core materials for magnetic parts such as transformers and reactors used in such switching power supplies.
金属磁性材料は、一般に高い飽和磁束密度と透磁率を有する。しかしながら、金属磁性材料は電気抵抗率が低いため、特に高周波数領域では渦電流損失が大きくなってしまう。スイッチング電源では、近年、電源回路を高周波駆動して必要なインダクタンス値を下げることにより、高効率化および小型化する傾向にあるが、上記の渦電流損失の影響から金属磁性材料を高周波で使用することはできない。 Metallic magnetic materials generally have a high saturation magnetic flux density and magnetic permeability. However, since the metal magnetic material has a low electrical resistivity, eddy current loss increases particularly in a high frequency region. In recent years, switching power supplies tend to be highly efficient and downsized by driving the power supply circuit at a high frequency to lower the required inductance value. However, metal magnetic materials are used at a high frequency because of the eddy current loss. It is not possible.
一方、酸化物磁性材料は、金属磁性材料に比べ電気抵抗率が高いため、高周波数領域でも発生する過電流損失が小さい。しかしながら、飽和磁束密度は金属磁性材料に比べて小さいため、その体積を小さくすることはできなかった。
つまり、いずれの場合でも磁性材料自体の体積がインダクタンス値を決定付ける一番大きな要因となっていて、磁性材料自体の磁気特性を向上させない限り、小型・薄型化が困難となっていた。
On the other hand, an oxide magnetic material has a higher electrical resistivity than a metal magnetic material, and therefore, an overcurrent loss that occurs even in a high frequency region is small. However, since the saturation magnetic flux density is smaller than that of the metal magnetic material, the volume cannot be reduced.
That is, in any case, the volume of the magnetic material itself is the biggest factor determining the inductance value, and it has been difficult to reduce the size and thickness unless the magnetic properties of the magnetic material itself are improved.
また、磁気部品の小型化のためには、飽和磁束密度だけではなく、直流重畳特性(直流磁界印加時の実効透磁率)、特に高磁界下での直流重畳特性が優れることが重要である。磁気部品を小型化した場合、磁路長が短くなるために動作磁界が高磁界側にシフトするためである。
直流重畳特性を向上させるために、金属磁性粉末を偏平化して形状異方性を発現させたものを磁路の方向に対して垂直な磁場により配向させた状態で圧粉成型して圧粉磁心とする提案がある（例えば、特許文献１参照。）。
Further, in order to reduce the size of the magnetic component, it is important that not only the saturation magnetic flux density but also the DC superimposition characteristics (effective permeability when a DC magnetic field is applied), particularly the DC superimposition characteristics under a high magnetic field are excellent. This is because when the magnetic component is reduced in size, the magnetic path length is shortened and the operating magnetic field is shifted to the high magnetic field side.
In order to improve the DC superimposition characteristics, a powder magnetic core is formed by compacting a metal magnetic powder to develop shape anisotropy and aligning it with a magnetic field perpendicular to the direction of the magnetic path. (For example, refer to Patent Document 1).
上記提案では１００ｋＨｚ程度の周波数では良好な直流重畳特性を示すが、１ＭＨｚ以上という高周波帯域では透磁率が低いという問題があった。
すなわち、本発明の目的は、高周波帯域での透磁率が高く、かつ、直流重畳特性に優れた圧粉磁心を提供することにある。
In the above proposal, a good DC superposition characteristic is shown at a frequency of about 100 kHz, but there is a problem that the magnetic permeability is low in a high frequency band of 1 MHz or more.
That is, an object of the present invention is to provide a dust core having a high magnetic permeability in a high frequency band and an excellent direct current superposition characteristic.
すなわち、本発明の圧粉磁心は、絶縁体で被覆された金属磁性粉末の磁化容易軸を磁路に垂直な方向に配向させて圧縮成型して作成され、該金属磁性粉末表面の磁路に垂直な方向の絶縁膜の厚さが、磁路方向の絶縁膜の厚さより厚いことを特徴とする。 That is, the dust core of the present invention is formed by compression molding with the easy axis of magnetization of the metal magnetic powder coated with an insulator oriented in a direction perpendicular to the magnetic path, and is formed on the magnetic path on the surface of the metal magnetic powder. The thickness of the insulating film in the vertical direction is greater than the thickness of the insulating film in the magnetic path direction.
本発明の圧粉磁心は絶縁体で被覆された金属磁性粉末の磁化容易軸を磁路に垂直な方向に配向して圧縮成型しているので、直流重畳特性に優れた圧粉磁心となる。また、磁路に垂直な方向の絶縁膜の厚さを、磁路方向の絶縁膜の厚さより厚くしているので、高周波帯域における透磁率の高い磁心となる。これにより、ノート型パソコンや携帯電話等の小型情報機器、薄型ＣＲＴ、テレビのフラットパネルディスプレイ等に用いられるスイッチング電源に向けた、高性能でかつ小型・薄型の磁気部品を作製することができる。 Since the powder magnetic core of the present invention is compression-molded with the easy axis of the metal magnetic powder coated with the insulator oriented in the direction perpendicular to the magnetic path, the powder magnetic core has excellent DC superposition characteristics. In addition, since the thickness of the insulating film in the direction perpendicular to the magnetic path is larger than the thickness of the insulating film in the magnetic path direction, the magnetic core has a high magnetic permeability in the high frequency band. As a result, it is possible to manufacture a high-performance, small and thin magnetic component for a switching power source used for a small information device such as a notebook personal computer or a mobile phone, a thin CRT, a flat panel display of a television.
以下、図面を参照して本発明を説明する。
図１は絶縁体で被覆された偏平化金属磁性粒子を示す模式図である。
本発明で用いる金属磁性粒子１における金属としては、例えば、鉄、コバルト、ニッケルなどの単金属、あるいはパーマロイ、センダストなどそれらを基とする合金などの透磁率が高い金属材料からなる粒子を用いることができる。
金属磁性粒子１の粒径（球換算）は特に限定されるものではないが、１〜３０μｍであることが好ましい。
The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing flattened metal magnetic particles coated with an insulator.
As the metal in the metal
The particle size (in terms of sphere) of the metal
金属磁性粒子の表面を被覆する絶縁体としては、フェライト、鉄酸化物等の高い電気抵抗率の酸化物、ガラス、シリカ、アルミナなどの絶縁性酸化物、シリコーン樹脂などの樹脂等を挙げることができる。
ガラスとしてはＳｉＯ２、Ｂ２Ｏ３、Ｐ２Ｏ５、Ｓｂ２Ｏ３等を主成分とするガラスを挙げることができる。
これらのなかでは金属磁性粒子間の反磁界を低減することで透磁率を高めることができることからフェライト、コバルタイト、クロマイト、マンガナイトなどの酸化物軟磁性体が好ましく、優れた軟磁気特性を示すフェライトが最も好ましい。
フェライトとしては、ＮｉＺｎフェライト、Ｃｏフェライト、ＣｏＺｎフェライト、Ｍｇフェライトやこれらを主成分とする複合フェライトを例示できる。すなわち、フェライトを構成する金属イオンとしては、鉄イオン、ニッケルイオン、亜鉛イオン、コバルトイオン、マグネシウムイオン、モリブデンイオン等を挙げることができる。もちろんこれらの金属イオンは所望のフェライトを構成するような金属イオンの種類、モル比とする。
Examples of the insulator covering the surface of the metal magnetic particles include oxides having high electrical resistivity such as ferrite and iron oxide, insulating oxides such as glass, silica and alumina, and resins such as silicone resins. it can.
The glass can be a glass mainly containing SiO 2, B 2 O 3, P 2
Among these, oxides such as ferrite, cobaltite, chromite, and manganite are preferred because they can increase the permeability by reducing the demagnetizing field between the metal magnetic particles, and ferrite exhibiting excellent soft magnetic properties. Is most preferred.
Examples of the ferrite include NiZn ferrite, Co ferrite, CoZn ferrite, Mg ferrite, and composite ferrite containing these as main components. That is, examples of the metal ions constituting the ferrite include iron ions, nickel ions, zinc ions, cobalt ions, magnesium ions, and molybdenum ions. Of course, these metal ions are of the kind and molar ratio of metal ions that constitute the desired ferrite.
絶縁体被覆した金属磁性粒子の平均被覆膜厚は圧縮成型後の成形体における絶縁体被覆層が保たれることにより粒子間の電気抵抗を高めることができる厚さであれば特に限定されないが、１０ｎｍ以上であることが好ましく、透磁率を高める観点から、２００ｎｍ以下であることが好ましい。
本発明においては、絶縁体被覆の膜厚は磁路に垂直な方向の絶縁膜の厚さが、磁路方向の絶縁膜の厚さより厚い必要がある。すなわち、磁路方向の絶縁膜の厚さが薄いと反磁界が小さくなり高い透磁性を得ることが可能となる。また、磁路に垂直な方向の絶縁膜が厚いと、全体の抵抗率の低下がなく、高周波特性に優れる圧粉磁心を得ることができる。
The average coating film thickness of the metal magnetic particles coated with the insulator is not particularly limited as long as the electrical resistance between the particles can be increased by maintaining the insulator coating layer in the compact after compression molding. The thickness is preferably 10 nm or more, and preferably 200 nm or less from the viewpoint of increasing the magnetic permeability.
In the present invention, it is necessary that the thickness of the insulating coating in the direction perpendicular to the magnetic path is larger than the thickness of the insulating film in the magnetic path direction. That is, when the thickness of the insulating film in the magnetic path direction is thin, the demagnetizing field is reduced and high permeability can be obtained. In addition, when the insulating film in the direction perpendicular to the magnetic path is thick, the whole resistivity does not decrease, and a dust core having excellent high frequency characteristics can be obtained.
金属磁性粒子を偏平化すると、その磁化困難軸が偏平な粒子の面に垂直な方向に現れる。これを磁心に予定される磁路の方向に対して垂直な方向の磁場の下に置くと、粒子の磁化容易軸が磁場の方向に配向する。従って、偏平化した金属磁性粒子を用い、絶縁膜の厚さを、短軸方向に薄く、長軸方向に厚くすると、これを上述のような磁場の下に置いたとき、長軸が磁路に垂直な方向を向くので、磁路に垂直な方向の絶縁膜の厚さが、磁路方向の絶縁膜の厚さより厚くなるので、金属磁性粒子として、偏平化金属磁性粒子を用いることが好ましい。偏平化金属磁性粒子としては、絶縁膜被覆前に偏平化したものでもよく、絶縁膜被覆後に偏平化したものでもよい。
偏平化方法としては、一般的にボールミルが用いられる。
When a metal magnetic particle is flattened, its hard axis appears in a direction perpendicular to the plane of the flat particle. When this is placed under a magnetic field in a direction perpendicular to the direction of the magnetic path planned for the magnetic core, the easy axis of magnetization of the particles is oriented in the direction of the magnetic field. Therefore, when flattened metal magnetic particles are used and the thickness of the insulating film is thin in the minor axis direction and thick in the major axis direction, the major axis becomes a magnetic path when placed under a magnetic field as described above. Since the thickness of the insulating film in the direction perpendicular to the magnetic path is larger than the thickness of the insulating film in the magnetic path direction, it is preferable to use flattened metal magnetic particles as the metal magnetic particles. . The flattened metal magnetic particles may be flattened before the insulating film is coated or may be flattened after the insulating film is coated.
As a flattening method, a ball mill is generally used.
本発明の絶縁体で被覆された偏平化金属磁性粉末のアスペクト比は２〜１０であることが好ましい。アスペクト比が２未満であると、偏平化率が不十分で充分高い透磁性の圧粉磁心を得難くなる。一方、アスペクト比が１０を超えると、絶縁体被覆金属磁性粒子を偏平化する場合は、偏平化時に絶縁体被覆が破れて金属磁性体が露出し、金属磁性体粒子同士が導通して、低電気抵抗の層が形成されるおそれがあることや、圧縮成型時の充填率が向上できなくなるという不具合が生じる。。 The aspect ratio of the flattened metal magnetic powder coated with the insulator of the present invention is preferably 2 to 10. When the aspect ratio is less than 2, it is difficult to obtain a sufficiently high magnetic permeability magnetic core with an insufficient flattening rate. On the other hand, when the aspect ratio exceeds 10, when the insulator-coated metal magnetic particles are flattened, the insulator coating is broken during the flattening to expose the metal magnetic material, and the metal magnetic particles are electrically connected to each other. There arises a problem that an electric resistance layer may be formed and a filling rate at the time of compression molding cannot be improved. .
絶縁体被覆の膜厚を、磁路に垂直な方向の絶縁膜の厚さが、磁路方向の絶縁膜の厚さより厚くする方法としては、シリコーン樹脂などの展延性に優れた樹脂を被覆した金属磁性粒子をボールミル等により押し潰し、偏平化する方法、偏平化金属磁性粒子表面にフェライトめっきする方法などを挙げることができる。展延性に優れた樹脂を被覆した金属磁性粒子を押し潰すと、押し潰されて形成された金属磁性粒子の短軸方向の絶縁膜はその圧力により展延されて長軸方向に移動するため、短軸方向が薄く、長軸方向が厚くなる。
偏平化金属磁性粒子表面にフェライトめっきすると、曲率半径の大きな短軸方向の膜厚が薄く、曲率半径の小さな長軸方向の膜厚が厚くなるという性質があり、これを利用することにより、短軸方向が薄く、長軸方向が厚いフェライトめっき膜を得ることができる。
As a method of making the insulation coating thickness so that the thickness of the insulating film in the direction perpendicular to the magnetic path is larger than the thickness of the insulating film in the magnetic path direction, a resin having excellent spreadability such as silicone resin is coated. Examples thereof include a method in which the metal magnetic particles are crushed by a ball mill or the like and flattened, and a method in which the surface of the flattened metal magnetic particles is plated with ferrite. When crushing metal magnetic particles coated with a resin with excellent spreadability, the insulating film in the short axis direction of the metal magnetic particles formed by crushing is spread by the pressure and moves in the long axis direction. The short axis direction is thin and the long axis direction is thick.
Ferrite plating on the surface of the flattened metal magnetic particles has the property that the film thickness in the minor axis direction with a large radius of curvature is thin, and the film thickness in the major axis direction with a small radius of curvature is large. A ferrite plated film having a thin axial direction and a long major axis direction can be obtained.
フェライトめっき膜を形成するにあたっては、超音波励起を用いた超音波励起フェライトめっきを用いると、均質なめっき膜を形成することができるので好ましい。 In forming the ferrite plating film, it is preferable to use ultrasonic excitation ferrite plating using ultrasonic excitation because a homogeneous plating film can be formed.
フェライトめっき層は、例えば、次のようにして形成できる。
ＦｅＣｌ２あるいはその他の２価金属の塩化物などの２価金属イオン塩、および必要に応じてＦｅＣｌ３などの３価の鉄イオンを含むフェライトめっき反応液に偏平化金属磁性粒子を分散させ、液の温度を室温から１００℃未満の温度、例えば６０〜８０℃の範囲内で一定に保ちながら、フェライトめっきを行う。ここで、フェライトめっきは、例えば超音波ホーンにより超音波を加えることにより液を激しく運動させながら、亜硝酸などの酸化剤を徐々に加えて酸化することによって進行させ、また、ｐＨコントローラーにより、水酸化アンモニウムなどでｐＨを調整してほぼ中性の反応液中に金属磁性粒子を浸漬して行うことができる。また、金属磁性粒子の分散液のｐＨを調整してほぼ中性に保ちつつ、この分散液にフェライトを構成する金属イオンを溶解させた溶液と酸化剤溶液とをそれぞれ一定の速度で滴下して金属磁性粒子の表面にフェライト被膜を形成させてもよい。
The ferrite plating layer can be formed as follows, for example.
The flattened metal magnetic particles are dispersed in a ferrite plating reaction solution containing a divalent metal ion salt such as FeCl 2 or other divalent metal chloride and, if necessary, a trivalent iron ion such as FeCl 3. The ferrite plating is performed while keeping the temperature at a constant temperature within a range from room temperature to less than 100 ° C., for example, 60 to 80 ° C. Here, the ferrite plating is performed by gradually adding an oxidizing agent such as nitrous acid and oxidizing while moving the solution vigorously by applying ultrasonic waves with an ultrasonic horn. The pH can be adjusted with ammonium oxide or the like, and the metal magnetic particles can be immersed in a substantially neutral reaction solution. In addition, while adjusting the pH of the dispersion of the metal magnetic particles to keep it almost neutral, a solution in which the metal ions constituting the ferrite are dissolved in this dispersion and an oxidizer solution are dropped at a constant rate. A ferrite film may be formed on the surface of the metal magnetic particles.
フェライトめっき工程の実施にあたって、金属磁性粒子を例えば、硫酸と塩酸の混合水溶液中に浸漬する前処理を行うことが好ましい。この前処理時には例えば１９．５ｋＨｚの超音波など、超音波を印加しながら行うことが好ましい。この前処理時の溶液温度は６０〜８０℃とすることが好ましい。 In carrying out the ferrite plating step, it is preferable to perform a pretreatment of immersing the metal magnetic particles in, for example, a mixed aqueous solution of sulfuric acid and hydrochloric acid. The pretreatment is preferably performed while applying an ultrasonic wave such as an ultrasonic wave of 19.5 kHz. The solution temperature during this pretreatment is preferably 60 to 80 ° C.
以下に実施例により本発明をさらに説明する。 The following examples further illustrate the present invention.
［実施例１］
金属磁性粒子として、水アトマイズ法により作製したＮｉ78Ｍｏ5Ｆｅ粉末（平均粒径：８μｍ）を用いた。この粉末と、シリコーン樹脂（東芝シリコーン社製ＴＳＥ３９９１）とを混ぜ合わせ、その混合物をボールミル（φ１０ｍｍのステンレス製ボール、乾式、３０分間）で偏平化した。
偏平化後の粉末のアスペクト比は約１０であった。この偏平化処理では、シリコーン樹脂で被覆した金属磁性粉末を押し潰しているため、シリコーン樹脂被膜の厚さは短軸方向で薄くなる。偏平化処理で得られた粒子の絶縁膜の厚さは短軸方向で約０．１μｍ、長軸方向で約０．３μｍであった。
[Example 1]
As the metal magnetic particles, Ni78Mo5Fe powder (average particle size: 8 μm) prepared by a water atomization method was used. This powder was mixed with a silicone resin (TSE 3991 manufactured by Toshiba Silicone), and the mixture was flattened with a ball mill (φ10 mm stainless steel ball, dry, 30 minutes).
The aspect ratio of the powder after flattening was about 10. In this flattening treatment, since the metal magnetic powder coated with the silicone resin is crushed, the thickness of the silicone resin film is reduced in the minor axis direction. The thickness of the insulating film of the particles obtained by the flattening treatment was about 0.1 μm in the minor axis direction and about 0.3 μm in the major axis direction.
この偏平化された粉末を外径８ｍｍ、内径３ｍｍのリング状の超硬合金製金型に入れ、ラジアル方向に磁場を印加した状態で、１０ｔｏｎ／ｃｍ２（９８０．７ＭＰａ）の一軸プレスにより高さ３ｍｍのリング状圧粉体（リングコア）を得た。
得られたリングコア内部の偏平化金属磁性粒子の配向状態を示す模式図を図２に示す。磁路方向（Ａ方向）から見た断面図では磁路に垂直な方向に偏平粒子の長軸が揃い、磁路方向の絶縁膜の厚さは磁路に垂直な方向の絶縁膜の厚さより薄くなっている。
This flattened powder is put into a ring-shaped cemented carbide mold having an outer diameter of 8 mm and an inner diameter of 3 mm, and a magnetic field is applied in the radial direction by a uniaxial press of 10 ton / cm 2 (980.7 MPa). A ring-shaped green compact (ring core) having a thickness of 3 mm was obtained.
FIG. 2 is a schematic diagram showing the orientation state of the flattened metal magnetic particles inside the obtained ring core. In the cross-sectional view viewed from the magnetic path direction (direction A), the long axes of the flat particles are aligned in the direction perpendicular to the magnetic path, and the thickness of the insulating film in the magnetic path direction is greater than the thickness of the insulating film in the direction perpendicular to the magnetic path. It is getting thinner.
このリングコアに１次および２次巻線をそれぞれ５ターン巻き回し、Ｂ−Ｈアナライザにて複素透磁率μ＝μ’＋ｉμ”を１０ｋＨｚ〜１０ＭＨｚの周波数領域で測定した。
透磁率の周波数特性は、１０ｋＨｚから１０ＭＨｚまで平坦であった。
また、直流重畳特性はリングコアに２０ターン巻き回し、直流電流を通電して測定した。周波数１ＭＨｚにおける直流重畳特性の測定結果を図３に示す。
The primary and secondary windings were wound around this ring core for 5 turns, respectively, and the complex permeability μ = μ ′ + iμ ″ was measured in a frequency range of 10 kHz to 10 MHz with a BH analyzer.
The frequency characteristic of the permeability was flat from 10 kHz to 10 MHz.
The DC superposition characteristics were measured by winding 20 turns around the ring core and applying a direct current. The measurement result of the DC superposition characteristics at a frequency of 1 MHz is shown in FIG.
［比較例１］
金属磁性粒子として、水アトマイズ法により作製したＮｉ78Ｍｏ5Ｆｅ粉末（平均粒径：８μｍ）を用い、この粉末を実施例１と同様にしてシリコーン樹脂で被覆した。絶縁膜の厚みは約０．２μｍであった。この絶縁体被覆金属磁性粉末を用いた以外は実施例１と同様にしてリングコアを作製し、複素透磁率と直流重畳特性を測定した。
透磁率の周波数特性は、１０ｋＨｚから１０ＭＨｚまで平坦であった。
周波数１ＭＨｚにおける直流重畳特性の測定結果を実施例１の結果とともに図３に示す。
[Comparative Example 1]
Ni78Mo5Fe powder (average particle size: 8 μm) produced by the water atomization method was used as the metal magnetic particle, and this powder was coated with a silicone resin in the same manner as in Example 1. The thickness of the insulating film was about 0.2 μm. A ring core was produced in the same manner as in Example 1 except that this insulator-coated metal magnetic powder was used, and the complex permeability and DC superposition characteristics were measured.
The frequency characteristic of the permeability was flat from 10 kHz to 10 MHz.
The measurement result of the DC superposition characteristics at a frequency of 1 MHz is shown in FIG.
［比較例２］
金属磁性粒子として、水アトマイズ法により作製したＮｉ78Ｍｏ5Ｆｅ粉末（平均粒径：８μｍ）を用い、シリコーン樹脂で被覆する前に、実施例１と同様にしてボールミルで偏平化した。偏平化後の粉末のアスペクト比は約１０であった。
偏平化粉末を用いた以外は実施例１と同様にしてシリコーン樹脂で被覆した。絶縁膜の厚み波長軸方向、単軸方向ともほぼ等しく、その厚みは約０．２μｍであった。この絶縁体被覆金属磁性粉末を用いた以外は実施例１と同様にしてリングコアを作製し、複素透磁率と直流重畳特性を測定した。
透磁率の周波数特性は、１０ｋＨｚから１０ＭＨｚまで平坦であった。
周波数１ＭＨｚにおける直流重畳特性の測定結果を実施例１、比較例１の結果とともに図３に示す。
[Comparative Example 2]
Ni78Mo5Fe powder (average particle size: 8 μm) produced by the water atomization method was used as the metal magnetic particles, and flattened by a ball mill in the same manner as in Example 1 before coating with a silicone resin. The aspect ratio of the powder after flattening was about 10.
It was coated with a silicone resin in the same manner as in Example 1 except that the flattened powder was used. The thickness of the insulating film was almost equal in both the wavelength axis direction and the uniaxial direction, and the thickness was about 0.2 μm. A ring core was produced in the same manner as in Example 1 except that this insulator-coated metal magnetic powder was used, and the complex permeability and DC superposition characteristics were measured.
The frequency characteristic of the permeability was flat from 10 kHz to 10 MHz.
The measurement results of the DC superposition characteristics at a frequency of 1 MHz are shown in FIG. 3 together with the results of Example 1 and Comparative Example 1.
［実施例２］
金属磁性粒子として、水アトマイズ法により作製したＮｉ78Ｍｏ5Ｆｅ粉末（平均粒径：８μｍ）を用いた。この粉末を用いた以外は実施例１と同様にしてボールミルで偏平化した。偏平化後の粉末のアスペクト比は約１０であった。
この扁平粉末２０ｇを用い、フェライトメッキの前処理として、これらの粒子をＨ２Ｏ：３００ｍｌ＋４７％Ｈ２ＳＯ４：１２５０μｌ＋２ｍｏｌ／ｌ、ＨＣｌ：１２５０μｌの溶液中（液温７０℃）に入れて、５分間超音波を印加した。その後、純水を入れたガラス製の反応容器中にＮｉ78Ｍｏ5Ｆｅ粒子を移し替え、１９．５ｋＨｚの超音波を印加した。この反応容器に反応液（Ｈ２Ｏ：５００ｍｌ＋ＦｅＣｌ２・４Ｈ２Ｏ：３．９８ｇ＋ＮｉＣｌ２・６Ｈ２Ｏ：１．１９ｇ＋ＺｎＣｌ２：０．６８ｇ）および酸化液（Ｈ２Ｏ：５００ｍｌ＋ＮａＮＯ２：１．００ｇ）をそれぞれ３ｍｌ／ｍｉｎ、２ｍｌ／ｍｉｎの速度で供給しながら、適宜アンモニア水を滴下することによりｐＨを１０．０に保った。この時、メッキ層の温度を湯浴により６０℃に保った。このメッキ処理を６０分間行った。メッキ処理後、粒子を分級・乾燥して酸化物被覆金属磁性粒子を得た。以上の処理により、金属磁性粒子の表面に短軸方向で約５０ｎｍ、長軸方向で約２００ｎｍのＮｉ−Ｚｎ系フェライト被膜が形成された。
[Example 2]
As the metal magnetic particles, Ni78Mo5Fe powder (average particle size: 8 μm) prepared by a water atomization method was used. Flattening was performed by a ball mill in the same manner as in Example 1 except that this powder was used. The aspect ratio of the powder after flattening was about 10.
Using 20 g of this flat powder, as a pretreatment for ferrite plating, these particles were put in a solution of H 2 O: 300 ml + 47% H 2 SO 4 : 1250 μl + 2 mol / l, HCl: 1250 μl (liquid temperature 70 ° C.), 5 Ultrasonic waves were applied for a minute. Then, Ni78Mo5Fe particles were transferred into a glass reaction vessel containing pure water, and 19.5 kHz ultrasonic waves were applied. In this reaction vessel, the reaction solution (H 2 O: 500 ml + FeCl 2 .4H 2 O: 3.98 g + NiCl 2 .6H 2 O: 1.19 g + ZnCl 2 : 0.68 g) and the oxidation solution (H 2 O: 500 ml + NaNO 2 : 1.00 g) ) Was supplied at a rate of 3 ml / min and 2 ml / min, respectively, and the pH was kept at 10.0 by appropriately dropping ammonia water. At this time, the temperature of the plating layer was kept at 60 ° C. with a hot water bath. This plating process was performed for 60 minutes. After the plating treatment, the particles were classified and dried to obtain oxide-coated metal magnetic particles. As a result of the above treatment, a Ni—Zn ferrite film having a short axis direction of about 50 nm and a long axis direction of about 200 nm was formed on the surface of the metal magnetic particles.
こうして得られたフェライト被覆偏平化粉末を外径８ｍｍ、内径３ｍｍのリング状の超硬合金製金型に入れ、ラジアル方向に磁場を印加した状態で、１０ｔｏｎ／ｃｍ２（９８０．７ＭＰａ）の一軸プレスにより高さ３ｍｍのリングコア形状に成型した。このリングコアを大気中で６００℃の電気炉に１分間投入し、熱処理を行った。
得られたリングコア内部の構造は実施例１と同様、磁路方向から見た断面図では磁路に垂直な方向に偏平粒子の長軸が揃い、磁路方向の絶縁膜の厚さは磁路に垂直な方向の絶縁膜の厚さより薄くなっていた。
このリングコアに１次および２次巻線をそれぞれ５ターン巻回し、Ｂ−Ｈアナライザにて複素透磁率μ＝μ’＋ ｉμ”を１０ｋＨｚ〜１０ＭＨｚの周波数領域で測定した。
透磁率の周波数特性は、１０ｋＨｚから１０ＭＨｚまで平坦であった。
また、直流重畳特性はリングコアに２０ターン巻き回し、直流電流を通電して測定した。
周波数１ＭＨｚにおける直流重畳特性の測定結果を図４に示す。
The ferrite-coated flattened powder thus obtained was placed in a ring-shaped cemented carbide mold having an outer diameter of 8 mm and an inner diameter of 3 mm, and a uniaxial axis of 10 ton / cm 2 (980.7 MPa) was applied in a radial direction. It was molded into a ring core shape with a height of 3 mm by pressing. This ring core was put in an electric furnace at 600 ° C. for 1 minute in the atmosphere to perform heat treatment.
The structure inside the obtained ring core is the same as in Example 1, and in the cross-sectional view seen from the magnetic path direction, the long axes of the flat particles are aligned in the direction perpendicular to the magnetic path, and the thickness of the insulating film in the magnetic path direction is the magnetic path It was thinner than the thickness of the insulating film in the direction perpendicular to.
The ring core was wound with 5 turns of the primary and secondary windings, respectively, and the complex permeability μ = μ ′ + iμ ”was measured with a BH analyzer in a frequency range of 10 kHz to 10 MHz.
The frequency characteristic of the permeability was flat from 10 kHz to 10 MHz.
The DC superposition characteristics were measured by winding 20 turns around the ring core and applying a direct current.
FIG. 4 shows the measurement results of the DC superposition characteristics at a frequency of 1 MHz.
［比較例３］
金属磁性粒子として、水アトマイズ法により作製した偏平化前のＮｉ78Ｍｏ5Ｆｅ粉末（平均粒径：８μｍ）を用いた以外は実施例２と同様にしてフェライトめっきを行い、メッキ処理後、粒子を分級・乾燥して酸化物被覆金属磁性粒子を得た。得られた粒子の平均粒径は１０μｍ、フェライト皮膜はどの方向にもほぼ均一で、その平均膜厚は約１００ｎｍであった。
この酸化物被覆金属磁性粒子を用いた以外は実施例１と同様にして、外径８ｍｍ、内径３ｍｍ、高さ約３ｍｍのリングコアを得た。
このリングコアに１次および２次巻線をそれぞれ５ターン巻回し、Ｂ−Ｈアナライザにて複素透磁率μ＝μ’＋ ｉμ”を１０ｋＨｚ〜１０ＭＨｚの周波数領域で測定した。
また、直流重畳特性はリングコアに２０ターン巻き回し、直流電流を通電して測定した。透磁率の周波数特性は、１０ｋＨｚから１０ＭＨｚまで平坦であった。
周波数１ＭＨｚにおける直流重畳特性の測定結果を実施例２の結果とともに、図４に示す。
[Comparative Example 3]
Ferrite plating was performed in the same manner as in Example 2 except that Ni78Mo5Fe powder (average particle size: 8 μm) before flattening prepared by a water atomization method was used as metal magnetic particles, and after the plating treatment, the particles were classified and dried. Thus, oxide-coated metal magnetic particles were obtained. The average particle diameter of the obtained particles was 10 μm, the ferrite film was almost uniform in any direction, and the average film thickness was about 100 nm.
A ring core having an outer diameter of 8 mm, an inner diameter of 3 mm, and a height of about 3 mm was obtained in the same manner as in Example 1 except that the oxide-coated metal magnetic particles were used.
The ring core was wound with 5 turns of the primary and secondary windings, respectively, and the complex permeability μ = μ ′ + iμ ”was measured with a BH analyzer in a frequency range of 10 kHz to 10 MHz.
The DC superposition characteristics were measured by winding 20 turns around the ring core and applying a direct current. The frequency characteristic of the permeability was flat from 10 kHz to 10 MHz.
The measurement result of the DC superposition characteristics at a frequency of 1 MHz is shown in FIG.
図３から、直流重畳磁界がない場合、実施例１の透磁率が比較例１、２の透磁率よりも大きいことがわかる。これは比較例１では金属磁性粒子が球状、比較例２では金属磁性粒子が偏平状であっても、絶縁被膜が均一であるので特定の方向で反磁界が小さくなることがないのに対して、実施例１では短軸方向の絶縁被膜が他の方向に比べて薄く、この短軸方向が磁路方向を向いているので反磁界が小さくなり高い透磁率を示している。
また、直流重畳磁界を印加すると、比較例１では急激に透磁率が減少し、１６００Ａ／ｍの磁界でほぼ半減したことがわかる。一方、実施例１では、直流重畳磁界の印加に伴う透磁率の減少は小さく、直流重畳特性に優れていることがわかる。これは、偏平形状による形状異方性の効果によるものである。このように、磁路方向の絶縁体の厚さを磁路に垂直な方向の絶縁体の厚さより薄くした構造にすることによって、透磁率と直流重畳特性に優れた特性のものとすることができることがわかる。
3 that the magnetic permeability of Example 1 is larger than the magnetic permeability of Comparative Examples 1 and 2 when there is no DC superimposed magnetic field. In Comparative Example 1, the metal magnetic particles are spherical, and in Comparative Example 2, even though the metal magnetic particles are flat, the insulating film is uniform and the demagnetizing field does not decrease in a specific direction. In Example 1, the insulating film in the short axis direction is thinner than in the other directions, and since the short axis direction faces the magnetic path direction, the demagnetizing field is reduced and high magnetic permeability is exhibited.
In addition, it can be seen that when a DC superimposed magnetic field was applied, the permeability decreased sharply in Comparative Example 1 and was almost halved at a magnetic field of 1600 A / m. On the other hand, in Example 1, the decrease in the magnetic permeability due to the application of the DC superimposed magnetic field is small, and it can be seen that the DC superimposed characteristics are excellent. This is due to the effect of shape anisotropy due to the flat shape. In this way, by making the thickness of the insulator in the magnetic path direction thinner than the thickness of the insulator in the direction perpendicular to the magnetic path, it is possible to achieve characteristics with excellent magnetic permeability and direct current superposition characteristics. I can see that
図４から、直流重畳磁界がない場合、実施例２の透磁率が比較例３の透磁率よりも大きいことがわかる。また、直流重畳磁界を印加すると、比較例３では急激に透磁率が減少し、１１００Ａ／ｍの磁界でほぼ半減したことがわかる。一方、実施例２では、直流重畳磁界の印加とともに透磁率は減少したが、比較例３ほど顕著ではなく、２０００Ａ／ｍの磁界でも半減はしなかった。実施例１と比較例１、２の比較と同様、実施例２と比較例３の比較からも、本発明の構成にすることにより、透磁率と直流重畳特性に優れた圧粉磁心が得られることがわかる。 4 that the magnetic permeability of Example 2 is greater than the magnetic permeability of Comparative Example 3 when there is no DC superimposed magnetic field. In addition, it can be seen that when a DC superimposed magnetic field was applied, the magnetic permeability suddenly decreased in Comparative Example 3 and was almost halved at a magnetic field of 1100 A / m. On the other hand, in Example 2, the permeability decreased with the application of the DC superimposed magnetic field, but was not as remarkable as in Comparative Example 3, and was not halved even by a magnetic field of 2000 A / m. Similar to the comparison between Example 1 and Comparative Examples 1 and 2, from the comparison of Example 2 and Comparative Example 3, a dust core having excellent permeability and DC superposition characteristics can be obtained by using the configuration of the present invention. I understand that.
本発明の圧粉磁心は、ノート型パソコンや携帯電話等の小型情報機器、薄型ＣＲＴ、テレビのフラットパネルディスプレイ等に用いられるスイッチング電源用の高性能でかつ小型・薄型の磁気部品作製用として有用である。 The dust core of the present invention is useful for producing high-performance, small and thin magnetic components for switching power supplies used in small information devices such as notebook computers and mobile phones, thin CRTs, flat panel displays for televisions, etc. It is.
１ 金属磁性粒子
２ 絶縁体被膜
３ リングコア
４ リングコアの断面を示す図
５ 磁路方向
DESCRIPTION OF
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008181923A (en) * | 2007-01-23 | 2008-08-07 | Fuji Electric Device Technology Co Ltd | Magnetic component and manufacturing method thereof |
| JP2009212385A (en) * | 2008-03-05 | 2009-09-17 | Sumitomo Electric Ind Ltd | Composite soft magnetic material, powder magnetic core, and method of producing composite soft magnetic material |
| JP2010087366A (en) * | 2008-10-01 | 2010-04-15 | Kobe Steel Ltd | Metal powder for soft magnetic composite material, and soft magnetic composite material |
| JP2010283263A (en) * | 2009-06-08 | 2010-12-16 | Nec Tokin Corp | Non-contact power transmission device |
| US10090088B2 (en) | 2015-09-14 | 2018-10-02 | Kabushiki Kaisha Toshiba | Soft magnetic material, rotating electric machine, motor, and generator |
| KR20190034100A (en) * | 2017-09-22 | 2019-04-01 | 가부시키가이샤 무라타 세이사쿠쇼 | Composite magnetic material and coil component using same |
| JP2020017690A (en) * | 2018-07-27 | 2020-01-30 | 日本特殊陶業株式会社 | Dust core |
| US10580563B2 (en) | 2015-10-27 | 2020-03-03 | Samsung Electro-Mechanics Co., Ltd. | Coil component |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008181923A (en) * | 2007-01-23 | 2008-08-07 | Fuji Electric Device Technology Co Ltd | Magnetic component and manufacturing method thereof |
| JP2009212385A (en) * | 2008-03-05 | 2009-09-17 | Sumitomo Electric Ind Ltd | Composite soft magnetic material, powder magnetic core, and method of producing composite soft magnetic material |
| JP2010087366A (en) * | 2008-10-01 | 2010-04-15 | Kobe Steel Ltd | Metal powder for soft magnetic composite material, and soft magnetic composite material |
| JP2010283263A (en) * | 2009-06-08 | 2010-12-16 | Nec Tokin Corp | Non-contact power transmission device |
| US10090088B2 (en) | 2015-09-14 | 2018-10-02 | Kabushiki Kaisha Toshiba | Soft magnetic material, rotating electric machine, motor, and generator |
| US10580563B2 (en) | 2015-10-27 | 2020-03-03 | Samsung Electro-Mechanics Co., Ltd. | Coil component |
| KR20190034100A (en) * | 2017-09-22 | 2019-04-01 | 가부시키가이샤 무라타 세이사쿠쇼 | Composite magnetic material and coil component using same |
| KR102118260B1 (en) * | 2017-09-22 | 2020-06-02 | 가부시키가이샤 무라타 세이사쿠쇼 | Composite magnetic material and coil component using same |
| US11127525B2 (en) | 2017-09-22 | 2021-09-21 | Murata Manufacturing Co., Ltd. | Composite magnetic material and coil component using same |
| JP2020017690A (en) * | 2018-07-27 | 2020-01-30 | 日本特殊陶業株式会社 | Dust core |
| JP7133381B2 (en) | 2018-07-27 | 2022-09-08 | 日本特殊陶業株式会社 | dust core |
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