JP2721165B2 - Magnetic core for choke coil - Google Patents

Description

The present invention relates to a magnetic core for a choke coil suitable for use in a smoothing circuit such as a switching power supply, and in applications such as normal mode noise and signal rejection. It is. [Prior art] Conventionally, as a core for a smooth choke coil, a silicon steel core with a gap, a ferrite core with a gap,
o Permalloy dust cores, Fe-Al-Si dust cores, and amorphous cores with gaps have been used. Regarding the characteristics of these magnetic cores, for example,
It is described in the materials of the 1st Research Meeting P41-P58. [Problems to be Solved by the Invention] However, ferrite magnetic cores have a low saturation magnetic flux density and thus have poor direct current superposition characteristics, and silicon steel has a problem of large core loss at high frequencies. The Mo permalloy core has a DC superposition characteristic superior to that of ferrite, but has a saturation magnetic flux density of 7 to 8 KG, and the DC superposition characteristic is not always sufficient. A magnetic core with a gap using an Fe-based amorphous alloy has disadvantages in that beats occur due to large magnetostriction of the alloy, core loss increases due to distortion due to impregnation or cut, and temperature characteristics of direct current superposition characteristics are poor. On the other hand, a Co-based amorphous magnetic core with a gap usually has a saturation magnetic flux density of 10 KG or less, and the DC superimposition characteristic is not sufficient like a Mo permalloy dust core. Further, as a core for a normal mode choke coil used for a noise filter or the like, conventionally, a metal-based iron powder core has been mainly used, but these cores also have low magnetic permeability and poor DC superposition characteristics. Therefore, it is hard to say that the characteristics are satisfactory. An object of the present invention is to provide a novel core for a choke coil which has excellent permeability frequency characteristics, direct current superimposition characteristics, and temperature characteristics, and has a small core loss. [Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have found that the composition formula: (Fe _1-a M _a ) _{100-xy-z-α- β-γ} Cu _x Si _y M '
_α M ″ _β X _γ (atomic%) (where M is Co and / or Ni, and M ′ is Nb, Ta, Z
At least one element selected from the group consisting of r, Hf, Ti and Mo, M is V, Cr, Mn, Al, a white metal element, Sc, Y, Au, Zn, Sn, R
e, at least one element selected from the group consisting of Ag, X
Is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, α, β and γ
Are 0 ≦ a ≦ 0.3, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 25, 3 ≦ z ≦ 17, 10 ≦ y + z ≦ 30, 0.1 ≦ α ≦ 10, 0 ≦ β ≦ 10, 0 ≦ γ ≦ 10 Meet. ). At least 50% of the structure is composed of fine bccFe solid solution crystal grains, and the average of the grain sizes measured at the maximum size of each crystal grain is 1000 mm or less. In the formed magnetic core, a magnetic core having a gap in at least one or more places of a magnetic path is excellent in frequency characteristics of magnetic permeability, DC superimposition characteristics, temperature characteristics and small in core loss, and is a choke such as a smooth choke or a normal mode choke. The present inventors have found that it is most suitable for a magnetic core for a coil, and have reached the present invention. In the present invention, Cu is an essential element, and its content x
Ranges from 0.1 to 3 atomic%. If less than 0.1 atomic%
There is almost no effect of reducing the core loss by the addition of Cu, while if it is more than 3 atomic%, the core loss may be larger than that of the non-added one. In the present invention, the particularly preferable Cu content x is 0.5 to 2 atomic%. In this range, a core having a particularly small core loss and a high magnetic permeability can be obtained. The alloy according to the present invention is obtained by quenching an amorphous alloy having the above-described composition from a molten metal or by a vapor phase quenching method such as a sputtering method or a vapor deposition method. It can usually be obtained depending on the heat treatment step to be formed. Although the cause of the core loss reducing effect of Cu is not clear, it is considered as follows. Since the interaction parameter between Cu and Fe is positive and the solid solubility is low and tends to separate, heating the amorphous alloy causes Fe atoms or Cu atoms or Cu atoms to gather and form clusters. And composition fluctuations occur. For this reason, a large number of regions that are likely to be partially crystallized are formed, and fine crystal grains having the nuclei as the nuclei are generated. Since this crystal contains Fe as a main component and has almost no solid solubility of Fe and Cu, Cu is extruded around the fine crystal grains by crystallization, and the Cu concentration around the crystal grains increases. For this reason, it is considered that crystal grains are unlikely to grow. It is thought that crystal refinement occurs due to the large number of crystal nuclei due to the addition of Cu and the difficulty in growing crystal grains, but this effect is particularly markedly enhanced by the presence of Nb, Ta, W, Mo, Zr, Hf, Ti, etc. It is thought that it is possible. When Nb, Ta, W, Mo, Zr, Hf, Ti, etc. do not exist, the crystal grains are not very fine and the soft magnetic properties are poor. This alloy has a smaller magnetostriction than the Fe-based amorphous alloy due to the generation of a fine crystalline phase containing Fe as a main component, and the smaller magnetostriction reduces the magnetic anisotropy due to internal stress-strain. This is one of the reasons why the soft magnetic properties are improved.
It is considered one. When Cu is not added, the crystal grains are hard to be refined and a compound phase is easily formed, so that the magnetic properties are deteriorated by crystallization. Si and B are elements useful for refining the alloy and adjusting the magnetostriction. The alloy of the present invention is preferably obtained by forming an amorphous alloy by the effect of adding Si and B once and then forming fine crystal grains by heat treatment. The reason for limiting the Si content y is that if y exceeds 25 atomic%, magnetostriction increases under favorable conditions of soft magnetic properties, which is not preferable. The reason why the content z of B is limited is that if z is less than 3 atomic%, it is difficult to obtain a uniform crystal grain structure, core loss increases and deterioration occurs, and if z exceeds 17 atomic%, good heat treatment of soft magnetic properties is obtained. This is because magnetostriction increases under the conditions, which is not preferable. Regarding the value of the sum y + z of Si and B,
If y + z is less than 10 at%, it becomes difficult to form an amorphous state and magnetic properties deteriorate, which is not preferable. On the other hand, if y + z exceeds 30 at%, there is a remarkable decrease in saturation magnetic flux density, an increase in core loss and an increase in magnetostriction. . A more preferable range of the Si and B contents is 10 ≦ y ≦ 25, 3 ≦ z ≦ 12, 18 ≦ y + z ≦ 28. In this range, the saturation magnetostriction is in the range of −5 × 10 ⁻⁶ to + 5 × 10 ^−6. And it is easy to obtain a low-loss alloy. Particularly preferably, 11 ≦ y ≦ 24, 3 ≦ z ≦ 9, 18 ≦ y + z ≦ 27
In this range, an alloy having a saturation magnetostriction in the range of −1.5 × 10 ⁻⁶ to + 1.5 × 10 ⁻⁶ and less deterioration due to impregnation or the like is easily obtained, and the temperature characteristics of the impregnated magnetic core are improved. In the alloy according to the present invention, M ′ has an action of refining crystal grains precipitated by complex addition with Cu, and is selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo. At least one element. Nb, etc. has the effect of raising the crystallization temperature of the alloy, but forms clusters and has the effect of lowering the crystallization temperature. it is conceivable that. The content α of M ′ is preferably in the range of 0.1 ≦ α ≦ 10. If α is less than 0.1 at%, it is difficult to obtain a core having a low core loss, and if it exceeds 10 at%, the saturation magnetic flux density is remarkably reduced. The preferred range of α is 2 ≦ α ≦ 8, and particularly low loss characteristics can be obtained in this range. The addition of M ″ improves corrosion resistance, improves magnetic properties,
Alternatively, an effect of adjusting magnetostriction or the like can be obtained. When M ″ exceeds 10 atomic%, the saturation magnetic flux density is remarkably reduced. In the magnetic core of the present invention, at least one kind selected from the group consisting of C, Ge, P, Ga, Sb, In, Be, As, etc. An alloy containing 10 atomic% or less of elements can be used.These elements are effective elements for amorphization, and can be added together with Si and B to help the alloy to become amorphous, and to control magnetostriction and Curie temperature. The balance is substantially Fe-excluding impurities, but the balance is Fe.
May be substituted by the component M (Co and / or Ni). The content of M is 0 ≦ a ≦ 0.3, but if it exceeds 0.3, the magnetostriction increases and the core loss increases. The alloy according to the magnetic core of the present invention is an alloy mainly composed of an iron solid solution having a bcc structure, but includes an amorphous phase, a compound of a transition metal such as Fe ₂ B, Fe ₃ B, Nb, and an ordered phase of Fe ₃ Si. There is also. These phases may degrade the magnetic properties. Particularly, a compound phase such as Fe ₂ B tends to deteriorate soft magnetic characteristics. Therefore, it is desirable that these phases do not exist as much as possible. The alloy according to the magnetic core of the present invention is composed of ultrafine and uniformly distributed crystal grains having a grain size of 1000 mm or less. In the case of an alloy exhibiting excellent soft magnetism, the grain size is often 500 mm or less. Particularly excellent soft magnetism is easily obtained when the average particle size is 20 to 200 °, and excellent characteristics are obtained when used in a magnetic core for a choke coil. These crystal grains are mainly composed of α-Fe solid solution,
Are considered to be in solid solution. The portion other than the fine crystal grains in the alloy structure is mainly amorphous. It should be noted that the core of the present invention exhibits a sufficiently low core loss even when the proportion of fine crystal grains is substantially 100%. In addition, unavoidable impurities such as N, O, S, and Ca, Sr, Ba, Mg, etc., are considered to be the same as the alloy composition used in the magnetic core of the present invention even if they are contained to such an extent that the desired characteristics are not deteriorated. Of course you can. The alloy used for the magnetic core of the present invention may be formed by a single-roll method, a twin-roll method, a centrifugal quenching method, or the like, and then heat-treating the amorphous ribbon to form fine crystal grains, vapor deposition, sputtering, ion Various methods such as a method of producing an amorphous film by plating and then heat treating and crystallizing, a method of spinning in a rotating liquid or a glass coating spinning method, obtaining an amorphous wire, and then heat treating and crystallizing. can do. Therefore, the magnetic core for a choke coil of the present invention is a wire, a ribbon,
Various shapes such as membranes can be used. However, generally, the use of a ribbon is most suitable as a magnetic core for a choke coil. The heat treatment performed to obtain the magnetic core of the present invention is performed for the purpose of reducing the internal strain, reducing the core loss by forming a fine grain structure, and reducing the magnetostriction. The heat treatment is usually performed in a vacuum or in an inert gas atmosphere such as a hydrogen gas, a nitrogen gas, and an argon gas.
However, depending on the case, it may be performed in an oxidizing atmosphere such as the air. The heat treatment temperature and time vary depending on the shape, size, and composition of the magnetic core made of the amorphous alloy ribbon, but it is generally desirable that the heat treatment is performed at 450 ° C. to 700 ° C., which is higher than the crystallization temperature, for about 5 minutes to 24 hours. Conditions for temperature rise and cooling during the heat treatment can be arbitrarily changed according to the situation. Further, heat treatment may be performed a plurality of times at the same temperature or different temperatures, or heat treatment may be performed in a multi-step heat treatment pattern. Furthermore, the alloy can be heat-treated in a DC or AC magnetic field.
Magnetic anisotropy can be generated in the present alloy by heat treatment in a magnetic field. The magnetic field does not need to be applied during the heat treatment, and a sufficient effect can be obtained if it is applied at a temperature lower than the Curie temperature Tc of the alloy according to the present invention. The Curie temperature of the alloy according to the present invention is higher than the Curie temperature of the main phase formed by heat treatment as compared with the case of the amorphous alloy, and heat treatment in a magnetic field can be applied even at a temperature higher than the Curie temperature of the amorphous alloy. The heat treatment in a rotating magnetic field may be performed in part or all of the heat treatment process. In addition, it is also possible to heat-treat the core by applying a current to the core or applying a high-frequency magnetic field to generate heat in the alloy during the heat treatment. In the case of heat treatment in a magnetic field, the heat treatment can be performed in two or more stages. Further, the magnetic properties can be adjusted by performing a heat treatment while applying tension or compression force. The magnetic core for a choke coil of the present invention is usually manufactured as follows. First, as described above, an amorphous ribbon is produced by a single roll method, a twin roll method, or the like, and is wound in a toroidal shape,
Type, I-shaped, U-shaped, U-shaped, C-shaped, etc.
After forming by pressing or cutting, and after heat treatment as described above, after performing the steps of impregnation, lamination and bonding, in the case of a toroidal wound core, a gap is formed by a slicer, etc. I do. In the case of a laminated magnetic core, the core may be cut as needed, but usually a combined core is used, and a gap is formed by inserting a spacer or creating a space in a part of the magnetic path. In the case of a cut core, a spacer is arranged on the mating surface to form a gap. The gap is formed to prevent magnetic saturation of the magnetic core and to improve the DC bias characteristics. In the case of a wound core, the impregnation makes it easier to form the gap with high accuracy, and a favorable result is obtained. In addition, it is preferable to dispose a spacer in the gap portion, because fluctuation of the gap width can be reduced and a magnetic core for a choke coil having small fluctuation can be obtained. In addition, when used for a smoothing choke of a switching power supply or the like, a choke coil having a non-linear characteristic such that an inductance increases at a low current may be required in order to solve a problem that an output voltage increases at a low current. . For such a purpose, a magnetic core having the following structure is preferable. One structure is a magnetic core using a plate-like ferrite core having a low saturation magnetic flux density for the spacer, and the ferrite saturates first to obtain nonlinear characteristics. Also, a high-permeability magnetic core such as a ferrite core, a permalloy magnetic core, an amorphous magnetic core, or the like having a closed magnetic circuit, and a magnetic core having the above-described gap provided at at least one position in the magnetic circuit can also provide excellent non-linear DC superposition characteristics. be able to. When a ferrite bobbin or a case is used as the high magnetic permeability core, non-linear characteristics are obtained and the effect of protecting the magnetic core is more preferable. A non-linear DC superimposition characteristic can also be obtained by arranging (bonding or winding) a high magnetic permeability core such as ferrite, amorphous, permalloy or the like in the vicinity of the gap of the magnetic core with a gap. Even when the gap is partially formed so that a part of the magnetic core is connected, a non-linear DC superposition characteristic can be obtained. In order to further reduce the size of the magnetic core of the present invention for use in a choke coil and use it, an Sm-Co magnet, Fe-Nd-B magnet or the like may be arranged in the gap portion to apply a bias magnetic field to form a polarized choke. In this case, the DC superimposition characteristic is significantly improved when DC is superimposed in a certain direction. The magnetic core of the present invention includes a wound core and a laminated magnetic core. In particular, when used at a high frequency or when a wide alloy ribbon is used, it is better to form an insulating layer on a part or the front surface of the alloy ribbon. Can be reduced, and a preferable result is obtained. Of course, this insulating layer may be on one side or both sides of the alloy ribbon. The method of forming the insulating layer to be formed is, for example, SiO ₂ , MgO, Al ₂ O ₃
Immersion, spraying or electrophoresis, or applying a film such as SiO ₂ or nitride by sputtering or vapor deposition, or adding an acid to an alcohol solution containing modified alkyl silicate. And a method of forming a forsterite (Mg ₂ SiO ₄ ) layer by heat treatment, and a method of forming a Cr oxide.
Moreover, applying a mixture of various ceramic powder raw material SiO ₂ -TiO ₂ type metal alkoxide partial hydrolysis sol, drying heating was dipped An alloy strip, after coating or dipping the solution consisting mainly of Chiranoporima The insulating layer can be formed by heating, applying a phosphate solution, and then heating. Further, an oxide layer or a nitride layer of Si or the like can be formed on the surface by heat treatment, or an oxide layer or a nitride layer can be formed by surface treatment with a chemical to form an insulating layer on the alloy surface. In the case of a wound core, the alloy ribbon and the insulating tape may be overlapped and wound to perform interlayer insulation. As the insulating tape, a polyimide tape, a ceramic fiber tape, a polyester tape, an araside tape, a glass fiber tape, or the like can be used. When a tape having excellent heat resistance is used, the magnetic core of the present invention is obtained by superposing and winding an amorphous alloy ribbon having the same composition as the alloy ribbon to form a wound core and then heat-treating the alloy to crystallize the alloy. Can be. In the case of a tall core, a structure in which a plurality of cores are stacked and integrated in the height direction of the cores to reduce eddy current loss caused by magnetic flux leaking from the gap is preferred. Is preferred. In the case of a laminated magnetic core, interlayer insulation can be performed by inserting a thin plate-shaped insulator into one or more layers of the alloy ribbon. In this case, an insulator without plasticity can be used. For example, a ceramic plate, a glass plate, a mica plate, and the like can be given. Also in this case, when an insulator having excellent heat resistance is used, heat treatment is performed after inserting and laminating a thin plate-like insulator for each one or more layers of the amorphous alloy ribbon having the same composition as the alloy ribbon. The magnetic core of the present invention can be obtained by crystallization. The magnetic core of the present invention has a characteristic that there is no remarkable deterioration in characteristics as in the conventional Fe-based amorphous core even when impregnated, and the magnetic core of the present invention such as a core with a gap formed after impregnation and a cut core has excellent characteristics. Can be obtained as The impregnation is usually performed after the heat treatment, but when a heat-resistant impregnating agent is used, the impregnation may be performed before the heat treatment. In this case, curing can be performed also as heat treatment. Epoxy resin, polyimide resin,
Varnishes containing a modified alkyl silicate as a main component, silicone resins and the like can be used. In the case of a wound core using an alloy ribbon manufactured by a single roll method, the surface in contact with the roll may be wound inside or outside may be wound when the ribbon is manufactured, but it may be wound outside, In the case of winding, it is easier to make a wound core by winding the surface in contact with the roll to the outside, and the space factor of the core can be increased. In the case of manufacturing a wound core, winding the ribbon while applying tension increases the space factor and provides a preferable result. It is desirable to fix the beginning and / or end of the winding when manufacturing the wound core. As a fixing method, a method of locally melting and joining by laser light irradiation or electric energy, a heat-resistant adhesive or tape There is a method of fixing by. The magnetic core obtained by such a method hardly loses the shape of the wound core during the heat treatment, is easy to handle after the heat treatment, and can obtain preferable results. In the magnetic core of the present invention, the surface of the ribbon to be used can be plated or coated to improve the corrosion resistance and the like. In addition, by putting in a bobbin or a case made of an insulating material or coating the periphery of the magnetic core, it is possible to prevent characteristic deterioration and breakage due to rust, and to insulate the windings when a choke coil is made. Examples of the material of the bobbin and the case include a phenol resin and a ceramic. A metal such as aluminum or stainless steel may be used as the bobbin, but in this case, the bobbin is often further coated. An epoxy resin or the like can be used as the coating material. In particular, when rust is a problem, it is preferable to use a silicone oil or the like. When using a case or bobbin, silicone rubber or grease may be filled as a buffer. In the case of a large magnetic core or cut core, a method of preventing deformation or damage by disposing a metal at the central portion or the outer peripheral portion, or fixing the outer peripheral portion with a metal band to prevent the deformation can be performed. In addition, by wrapping the insulating tape around the magnetic core, rust can be prevented or damage can be prevented, and electrical insulation can be performed. Also in the case of the thinned magnetic core of the present invention, a gap is formed by cutting, or a part where the alloy film according to the present invention is not formed in a part of the magnetic path, and is formed of an alloy film suitable for a choke coil by forming a gap. You can get a magnetic core. Further, it can be used as a laminated film via an insulating layer such as SiO ₂ in order to improve high frequency characteristics. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 From a molten metal having a composition consisting of 1% of Cu, 13.5% of Si, 9% of B, 3% of Nb and the balance of substantially Fe in atomic%, the width was determined by a single roll method.
A ribbon having a thickness of 5 mm and a thickness of 18 μm was produced. When the ribbon was subjected to X-ray diffraction, a halo pattern peculiar to amorphous was obtained, and it was confirmed that most of the halo pattern was composed of an amorphous phase. Next, the alloy ribbon was wound around an outer diameter of 18 mm and an inner diameter of 11 mm, placed in a tubular furnace heated to 550 ° C. by flowing nitrogen gas as a wound core, held for 1 hour, taken out of the furnace, and air-cooled. Next, this wound core is vacuum impregnated with an epoxy resin, and after curing, cut with an outer peripheral slicer to form a gap.
A non-magnetic spacer having a length of m was sandwiched between them to prepare a magnetic core for a choke coil of the present invention having a shape as shown in FIG. The magnetic core is further coated with powder using epoxy resin, 0.8mmφ
Was wound for about 30 turns, and the DC bias characteristics were measured.
The results obtained are shown in FIG. The DC superposition characteristics of the conventional magnetic core are also shown for comparison. FIG. 3 shows DC superimposition characteristics at room temperature and 100 ° C. of a core for a choke coil using an Fe-based amorphous alloy and the core of the present invention. As can be seen from the figure, the DC superposition characteristics of the magnetic core of the present invention are remarkably superior to conventional Mo permalloy powder cores, ferrite cores, Fe powder cores, and the like. Remarkably small. Therefore, a highly reliable and high-performance small choke coil can be manufactured. FIG. 4 shows the frequency dependence of the core loss. The core of the present invention has a smaller core loss than the Fe-based amorphous core, and generates less heat from the core, which is advantageous in terms of thermal design. The structure of the heat-treated alloy according to the present invention was confirmed to be an alloy mainly composed of ultrafine bccFe solid solution crystal grains having a grain size of 100 to 200 ° as shown in FIG. As described above, the magnetic core of the present invention is excellent in DC superimposition characteristics, good in temperature characteristics, and low in core loss, and thus is most suitable for smooth chokes and normal mode chokes. Example 2 From a molten metal having a composition consisting of 1% of Cu, 13% of Si, 8% of B, 3% of Nb, 1% of Cr and the balance of substantially Fe, the width is 10 mm and the thickness is 15%.
A μm ribbon was produced. Next, MgO powder was adhered to the surface of the ribbon by electrophoresis to form an insulating layer.
A wound core having a shape as shown in the figure was produced. Next, the wound core was heat-treated in Ar gas at 530 ° C. for 1 hour and cooled to room temperature. The structure of the alloy used was the same as in Example 1.
Was similar to Next, the wound core was vacuum impregnated with an epoxy resin, cured, and the center was cut to produce a cut core. Next, the cut surface was ground and a magnetic core of the present invention as shown in FIG. 7 was produced via a non-magnetic spacer of 0.2 mm. FIG. 8 shows the frequency dependence of the effective magnetic permeability μe. For comparison, μ of conventional Fe-based amorphous core with gap and Mo permalloy dust core
The frequency dependence of e is also shown. The value of μe of the magnetic core for a choke coil of the present invention is higher than that of a Mo permalloy dust core or the like over a wide frequency range, and the frequency characteristics are good. Example 3 A ribbon of Fe ₇₆ Cu ₁ Nb _2.5 Si _13.5 B ₇ alloy having a width of 25 mm and a thickness of 20 μm was prepared by a single roll method, and an E-shaped ribbon was prepared by photoetching, and Al ₂ O ₃ powder was produced. An insulating layer was formed on the surface by immersion in a dissolved alcohol solution and then heat-treated at 550 ° C. for 1 hour. The structure of the alloy used was the same as in Example 1.
Was similar to Next, an epoxy-based adhesive was applied to the surface of the E-shaped ribbon, laminated and cured to produce an EE-shaped core of the present invention having a gap as shown in FIG. For comparison, a Fe-based amorphous magnetic core having the same shape was prepared, and a bobbin with a winding was fitted to the center leg, and the temperature rise was measured using a smoothing choke of a switching power supply. As a result, the temperature rise of the core of the present invention was 36 ° C, and that of the Fe-based amorphous core was 43 ° C.
In the magnetic core of the present invention, the temperature rise was lower. Example 4 From a molten metal having a composition consisting of 1% of Cu, 17% of Si, 6.5% of B, 0.5% of Ge, 3% of Nb and the balance of substantially Fe in atomic%, the width was 5 mm and the thickness was 5 mm.
An 18 μm amorphous ribbon was produced. Next, the ribbon is wound around an outer diameter of 18 mm and an inner diameter of 11 mm to form a toroidal core 2
Individual pieces were prepared, heat-treated at 530 ° C. for 1 hour, and impregnated with an epoxy resin. The microstructure of the alloy after the heat treatment was the same as in Example 1.
Was similar to Next, one magnetic core was formed with a gap of 0.5 mm by an outer peripheral slicer, and a nonmagnetic spacer was inserted. The other magnetic core did not form a gap, and the two magnetic cores were laminated and bonded in two steps to form a composite core. Next, the magnetic core was powder-coated with an epoxy resin, and the DC bias characteristics were measured. The results obtained are shown in FIG. As can be seen from the figure, since the inductor on the low current side has high nonlinear characteristics, it is suitable for a smoothing choke or the like of a switching power supply. Example 5 Cu 1.5%, Mo 3%, Si 13.5%, B 9%, Ti 0.5% at atomic%
An amorphous ribbon having a width of 10 mm and a thickness of 20 μm was prepared from a molten alloy having the following composition. Next, this core is 18mm in outer diameter and 11m in inner diameter.
The resultant was wound around m to form a toroidal magnetic core, impregnated with an inorganic varnish containing a modified alkyl silicate as a main component, heat-treated at 520 ° C. for 1 hour, and formed a partial gap as shown in FIG. 11 with an outer peripheral slicer. The microstructure of the alloy after the heat treatment was the same as in Example 1. Next, the magnetic core was put in a case made of a phenol resin, and the DC bias characteristics were measured. As a result, the same non-linear characteristics as in Example 4 were obtained. Example 6 An amorphous alloy ribbon having a width of 5 mm and a thickness of 18 μm was prepared from a molten alloy having a composition of 1% Cu, 3% W, 13% Si, 8% B, and 1% Ga in atomic%. Prepare a 16mm toroidal core, heat treat it at 530 ° C for 1 hour, impregnate it with varnish, form a 0.5mm gap with outer peripheral slicer, and use a 0.5mm thick Mn-Zn ferrite plate as a spacer. I put it in the department. The alloy ribbon after the heat treatment had a structure mainly composed of ultrafine crystal grains as in Example 1. Next, the magnetic core was put in a case made of a phenol resin, and the DC bias characteristics were measured. As a result, it was confirmed that they exhibited nonlinear DC superimposition characteristics as in Examples 4 and 5. Example 7 An amorphous alloy ribbon having a width of 5 mm and a thickness of 15 μm was prepared from a molten alloy having a composition of 1.5% of Cu, 3% of Mo, 14% of Si, 8% of B, and 1% of Al by the single roll method. 21mm diameter, 16mm inner diameter
Toroidal core and heat-treated at 520 ° C for 1 hour,
After impregnation with a polyimide resin, a gap of 0.5 mm was formed at one place by a slicer, a spacer was inserted into the gap, and the gap was fixed. Then, the gap was placed in a core case made of Mn-Zn ferrite, and the DC bias characteristics were measured. As a result, as in Example 6, it was confirmed that a non-linear DC superposition characteristic having a high inductance on the low current side was exhibited. The magnetic core material after the heat treatment had an ultrafine crystal grain structure similar to that of Example 1. Example 8 1% of Cu, 3% of Nb, 7% of Si, 9% of B, 10% of Co at the atomic% and the balance
From the molten alloy with the composition consisting of Fe, the width 10
An amorphous ribbon having a thickness of 28 μm and a thickness of 28 μm was produced. Next, while applying a varnish containing a modified alkyl silicate as a main component to the surface of this alloy, a wound core having the same shape as that of Example 2 was produced. Next, the wound core is heated at 550 ° C. for 1 hour with N
_It was heat-treated in _two gases and cooled to room temperature. The microstructure of the alloy after the heat treatment was the same as in Example 1. Next, the wound core was cut at the center to produce a cut core. Next, after wrapping the cut surface, bonding was performed via a non-magnetic spacer of 0.3 mm, and Co ₆₇ Fe with almost zero magnetostriction was further added.
_{A 4} Mo _1.5 Si _16.5 B ₁₁ amorphous alloy ribbon was wrapped around the gap, and the wrapping was performed to measure the DC bias characteristics. As a result, it was confirmed that a nonlinear characteristic having a large inductance was obtained on the low current side, and was suitable for a nonlinear choke. Example 9 An amorphous alloy ribbon having a width of 10 mm and a thickness of 17 μm was prepared from a molten alloy having a composition of 0.9% of Cu, 2% of Nb, 2% of Si, 13.5% of B, 9% of V, and the balance of Fe at 1% by atom. A U-shaped cut core was prepared in the same manner as in Example 2, a Sm-Co magnet was adhered to the mating surface, and the two U-shaped cores were joined and fixed. did. The results obtained are shown in FIG. It has been confirmed that the arrangement of the permanent magnet in the gap results in a polar characteristic, the DC superimposition characteristic is improved, and a high inductance can be obtained up to a large current side. Example 10 An impregnated wound core having an outer diameter of 18 mm, an inner diameter of 11 mm, and a gap of 0.5 mm made of the alloy of the present invention having a fine grain structure having the composition shown in Table 1 was produced, and a 30-turn 0.7 mmφ winding was performed.
25 ° C inductance when DC superimposed current of A flows
Measure L ₂₅ and inductance L ₁₀₀ at 100 ° C, I asked. Table 1 shows the obtained results. The magnetic core for a choke coil according to the present invention has a temperature change in inductance which is a conventional value.
It is significantly smaller than a magnetic core for a choke coil using Fe-based amorphous, and has excellent temperature characteristics. [Effects of the Invention] According to the present invention, it is possible to obtain a new core for a choke coil having excellent frequency characteristics of magnetic permeability, direct current superimposition characteristics, and temperature characteristics, and a small core loss. Since a coil can be obtained, the effect is remarkable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an embodiment of a magnetic core for a choke coil according to the present invention, and FIG. 2 shows an example of a DC superposition characteristic of the magnetic core according to the present invention in comparison with a conventional magnetic core. FIG. 3 is a diagram showing DC superimposition characteristics at 25 ° C. and 100 ° C. of a core according to the present invention and a core for a choke coil made of a conventional Fe-based amorphous alloy, and FIG. FIG. 5 is a diagram showing the frequency dependence of core loss of a conventional core for a choke coil, FIG. 5 is a schematic diagram of a structure of the alloy according to the present invention observed by a transmission electron microscope, and FIG. FIG. 7 is a diagram showing an embodiment of a wound core formed in stages, FIG. 7 is a diagram showing an embodiment of a core for a choke coil according to the present invention, and FIG. 8 is a core and a conventional choke according to the present invention. An example of the frequency dependence of the effective magnetic permeability μe of the coil core is shown. FIG. 9, FIG. 9 is a schematic diagram showing an embodiment of a choke coil core showing nonlinear characteristics according to the present invention, and FIG. 10 shows an example of DC superposition characteristics of a core showing nonlinear characteristics according to the present invention. FIG. 11, FIG. 11 is a schematic view showing an embodiment of a magnetic core showing nonlinear characteristics according to the present invention, and FIG. 12 is a diagram showing a direct current between a polarized choke coil magnetic core according to the present invention and a normal non-polarized choke coil magnetic core. FIG. 4 is a diagram illustrating an example of a superimposition characteristic.

Claims (1)

(57) [Claims] General formula (Fe _1-a M _a ) _{100-x-y-z-α-β-γ} Cu _x Si _y M ′
_α M ″ _β X _γ (atomic%) (where M is Co and / or Ni, and M ′ is Nb, W, Ta,
At least one element selected from the group consisting of Zr, Hf, Ti and Mo, M ″ is V, Cr, Mn, Al, a white metal element, Sc, Y, Au, Zn, Sn,
At least one element selected from the group consisting of Re, Ag,
X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, α, β and γ
Are respectively 0 ≦ a ≦ 0.3, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 25, 3 ≦ z ≦ 17,
10 ≦ y + z ≦ 30, 0.1 ≦ α ≦ 10, 0 ≦ β ≦ 10, and 0 ≦ γ ≦ 10. An alloy ribbon or alloy film having a composition represented by the following formula, wherein at least 50% of the structure is composed of fine bccFe solid solution crystal grains, and the average of the grain sizes measured at the maximum size of each crystal grain is 1000 mm or less. A magnetic core for a choke coil, characterized in that a gap is formed in at least one or more portions of a magnetic path in the magnetic core formed from. 2. The magnetic core for a choke coil according to claim 1, wherein the magnetic core is impregnated. 3. 3. The magnetic core for a choke coil according to claim 1, wherein a spacer is disposed in the gap. 4. 4. The core for a choke coil according to claim 3, wherein the spacer has a non-linear characteristic by using a ferrite core. 5. A magnetic core for a choke coil, wherein the magnetic core according to any one of claims 1 to 3 is combined with a high-permeability magnetic core to have nonlinear characteristics. 6. The core for a choke coil according to claim 5, wherein the high permeability core is a ferrite bobbin or a case. 7. 6. The core for a choke coil according to claim 5, wherein the high permeability core is disposed near the gap. 8. The magnetic core for a choke coil according to any one of claims 1 to 3, wherein a gap is partially formed so that a part of the magnetic core is connected to have a non-linear characteristic. 9. 3. The magnetic core for a choke coil according to claim 1, wherein a permanent magnet is arranged in the gap. 10. The toroidal winding core formed by winding the alloy ribbon, wherein a plurality of winding cores are overlapped in a height direction of the winding core to be integrated into a single body. Item 10. A magnetic core for a choke coil according to any one of items 9.