JP7123578B2 - Insulated wire for high frequency coil - Google Patents

Description

The present invention relates to an insulated wire for high-frequency coils, and more specifically, it is used for coils in the high-frequency field that use power semiconductors, such as motors, inverters, and contactless power supply. The present invention relates to an insulated wire for high-frequency coils that can be realized.

A litz wire obtained by twisting a plurality of insulated wires, a composite insulated wire obtained by further winding the litz wire with a tape or by melt-extrusion, or the like is used for the coil component. These insulated wires can suppress an increase in AC resistance due to the skin effect in a high frequency range of several tens of kHz to several hundreds of kHz, so they are widely used as coil wires in the field of high frequencies. In recent years, in particular, there has been a demand for miniaturization of coil components, and there has also been a demand for a reduction in the diameter of insulated wires for coils.

Patent Literature 1 proposes an insulated wire for a coil that can reduce the size of the coil and improve the space factor. In this technique, a plurality of compound-coated wires coated with an imidazole compound layer formed by forming a complex with the constituent metal of the wire are twisted to form a stranded wire, and the outer circumference of the wire is wrapped with tape, melt extrusion, or a combination thereof. It is configured with an insulating coating provided by

On the other hand, in the prior art column of Patent Document 2, a ferromagnetic thin film layer of iron or the like is formed by plating on the outer circumference of a copper conductor, and a nickel layer is formed on the outer circumference by plating to prevent rust. A magnetic wire is described in which an insulating coating is provided by applying and baking an insulating paint. When this magnetic wire is applied to various high-frequency coils, it is said to have the advantage of being able to significantly reduce high-frequency loss and improve the Q characteristic of the coil compared to conventional enameled copper wires.

By the way, in insulated wires for coils, good soldering is required as a terminal treatment. Therefore, a plated layer is provided on the outer circumference of the strand of copper or its alloy, aluminum or its alloy, copper-clad aluminum, or the like to achieve good soldering. As the material of the plating layer, one or two or more selected from tin, solder, nickel, gold, silver, copper and palladium are used for single plating, laminated plating or alloy plating.

JP 2016-134273 A Japanese Unexamined Patent Application Publication No. 2002-231060 (prior art column)

When trying to apply the imidazole compound layer proposed in Patent Document 1 to a wire provided with a plating layer with good solderability, complex formation between the constituent metal of the plating layer and the imidazole compound is extremely difficult (reaction slow). For example, copper-based metals such as copper, copper alloys, and copper-clad aluminum can easily form copper-imidazole complexes, but nickel, aluminum, tin, and solder have lower standard electrode potentials than copper. The lower the potential of the metal, the slower the reaction rate with the imidazole compound. Therefore, when trying to complex-form a compound layer with a required thickness, the processing time is as long as 30 minutes or longer, resulting in an increase in cost.

In addition, since metals such as silver, gold, and palladium have extremely stable potentials, imidazole complexes are difficult to form in the same manner as described above, and an imidazole compound layer having a sufficient thickness cannot be formed. Therefore, high-frequency characteristics equivalent to those of enamel-coated litz wires cannot be obtained. In order to obtain high-frequency characteristics equivalent to those of conventional enamel-coated litz wires, the thickness of the compound layer consisting of a metal-imidazole complex must exceed a certain level, and each wire must be effectively insulated. .

On the other hand, in the magnetic wire described in Patent Document 2, a ferromagnetic layer in which an iron layer and a nickel layer are laminated is formed on the outer periphery of a copper conductor to reduce AC resistance in a high frequency band. When trying to apply the imidazole compound layer proposed in Patent Document 1 to this magnetic wire, since the nickel layer is extremely thin, the underlying iron plating layer reacts with the imidazole complex forming solution and corrosion easily occurs. , there is a risk of spoiling the appearance. Moreover, when tape winding or foam extrusion is performed on the conductor after such corrosion has progressed, there is a risk that the tape or foam structure will be destroyed and a stable withstand voltage will not be obtained. If a uniform and good imidazole compound layer cannot be obtained, the effect of resistance loss in the high-frequency band cannot be achieved. may undermine the credibility of

The present invention has been made to solve the above problems, and its purpose is to be used as a coil in the high frequency field using power semiconductors such as motors, inverters, and contactless power supply. An object of the present invention is to provide an insulated wire for high-frequency coils capable of achieving high quality and high performance.

An insulated wire for a high-frequency coil according to the present invention includes a central conductor, a metal layer provided on the outer periphery of the central conductor and composed of copper and an iron group element, and a metal layer provided on the outer periphery of the metal layer. characterized by having a twisted wire obtained by twisting a plurality of compound layer-coated filaments each composed of a compound layer formed by forming a complex with a constituent metal, and an insulating layer provided on the outer circumference of the twisted wire. and

According to the present invention, since the thickness of the compound layer formed by forming a complex with the constituent metal of the metal layer is thin, the outer diameter of the insulated wire using the compound layer-coated wire coated with such a compound layer is small. , which is advantageous for the production of small coils. Also, since the metal layer contains copper with good solderability, terminal processing by soldering can be easily performed. Furthermore, since the metal layer contains copper, a stable compound layer is easily formed, and as a result, good insulation can be ensured. Furthermore, since the metal layer contains an iron group element, good shielding properties are obtained due to the magnetic function of the iron group element. As a result, a coil component obtained by processing this insulated wire into a coil or the like can achieve miniaturization, high quality, and high performance.

In the high-frequency coil insulated wire according to the present invention, it is preferable that the compound layer is made of a material that decomposes at a soldering temperature.

In the high frequency coil insulated wire according to the present invention, it is preferable that the compound layer is a copper imidazole compound layer formed by forming a complex with copper constituting the metal layer.

In the high-frequency coil insulated wire according to the present invention, the compound layer preferably has a thickness of 0.05 to 0.5 μm.

In the high-frequency coil insulated wire according to the present invention, the insulating layer is preferably selected from an insulating coating film, an insulating extruded resin, an insulating tape, and combinations thereof.

In the high-frequency coil insulated wire according to the present invention, the center conductor is preferably selected from tough pitch copper, oxygen-free copper, silver-containing copper, tin-containing copper, copper-clad aluminum, aluminum, and aluminum alloys.

In the high-frequency coil insulated wire according to the present invention, the metal layer is preferably selected from a copper-iron alloy, a copper-nickel alloy, and a copper-cobalt alloy.

In the high-frequency coil insulated wire according to the present invention, the content of one or more iron group elements selected from iron, nickel, and cobalt contained in the metal layer is in the range of 5 to 50% by mass. preferable.

According to the present invention, an insulated wire for high-frequency coils that can be used for coils in the high-frequency field that uses power semiconductors such as motors, inverters, and contactless power supply, and that can realize miniaturization, high quality, and high performance of coils is provided. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional configuration diagram showing an example of a compound layer-coated wire that constitutes an insulated wire for a high-frequency coil according to the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional block diagram which shows an example of the insulated wire for high frequency coils which concerns on this invention. FIG. 3 is an explanatory diagram of the insulated wire for high frequency coil of FIG. 2 ; It is a sectional block diagram which shows the example of the coil component (A) produced with the insulated wire for high frequency coils, and the sectional block diagram which shows the example of the coil component (B) produced with the conventional insulated wire for coils.

An insulated wire for high-frequency coils according to the present invention will be described with reference to the drawings. The present invention includes inventions having the same technical idea as the embodiments described below and the forms described in the drawings, and the technical scope of the present invention is limited only to the description of the embodiments and the description of the drawings. not something.

[Insulated wire for high frequency coil]
As shown in FIGS. 1 to 3, a high-frequency coil insulated wire 20 according to the present invention includes a stranded wire 11 obtained by twisting a plurality of compound layer-coated wires 10 and an insulation provided around the stranded wire 11. layer 4; Specifically, a central conductor 1, a metal layer 2 formed of copper and an iron group element provided on the outer periphery of the central conductor 1, and a metal layer 2 provided on the outer periphery of the metal layer 2 to form a complex with the constituent metals of the metal layer 2. It has a stranded wire 11 obtained by twisting a plurality of compound layer-covered wires 10 each made of a compound layer 3 and an insulating layer 4 provided on the outer periphery of the stranded wire 11 .

In this high frequency coil insulated wire 20, since the thickness of the compound layer 3 formed by forming a complex with the constituent metal of the metal layer 2 is thin, the insulation using the compound layer coated wire 10 coated with such a compound layer 3 is performed. The wire 20 has a smaller outer diameter, which is advantageous for manufacturing small coils. Also, since the metal layer 2 contains copper with good solderability, terminal processing by soldering can be easily performed. Furthermore, since the metal layer 2 contains copper, a stable compound layer 3 is easily formed, and as a result, good insulation can be ensured. Furthermore, since the metal layer 2 contains an iron group element, good shielding characteristics can be obtained due to the magnetic function of the iron group element. As a result, a coil component obtained by processing the insulated wire 20 into a coil or the like can achieve miniaturization, high quality, and high performance. In particular, it can be preferably used for coils (reactors, inductors, choke coils, noise filters, IH heaters, power transformers, etc.) in the high-frequency field using power semiconductors for motors, inverters, contactless power supply, and the like.

Each configuration will be described below.

<Compound layer covered wire>
The compound layer-coated wire 10 is a component of an insulated wire 20 for high frequency coils, as shown in FIGS. A plurality of compound layer-coated wires 10 are twisted together to form a stranded wire 11, and an insulating layer 4 is provided on the outer periphery of the stranded wire 11 to form an insulated wire 20 for a high frequency coil. Specifically, the compound layer-coated wire 10 includes a central conductor 1, a metal layer 2 provided on the outer periphery of the central conductor 1, and made of copper and an iron group element, and a metal layer 2 on the outer periphery of the metal layer 2. It is provided with a compound layer 3 formed by forming a complex with the constituent metal of the metal layer 2 .

(Center conductor)
As shown in FIG. 1, the central conductor 1 is a core conductor positioned at the center of the compound layer-coated wire 10, and various conductors can be applied as long as they serve as the central conductor of the coil insulated wire. Examples of materials for the central conductor 1 include copper or copper alloys, aluminum or aluminum alloys, copper clad materials, and the like. Examples of copper include tough pitch copper and oxygen-free copper. Copper alloys include copper-silver alloys (copper containing silver, such as copper containing 0.02 to 6% by mass of silver) and copper-tin alloys (copper containing tin, such as copper containing 0.15 to 7% by mass of tin). etc. can be mentioned. Whether tough pitch copper or oxygen-free copper can be determined by a hydrogen embrittlement test in accordance with JIS H-3510, copper-silver alloy (copper containing silver), copper-tin alloy (copper containing tin) , the contained element can be measured by ICP emission spectrometry for qualitative and quantitative analysis. Examples of aluminum and aluminum alloys include pure aluminum and various aluminum alloys applicable to insulated wires for coils. The copper clad material can also include copper clad aluminum applicable to the insulated wire for coils.

The central conductor 1 has a conductivity applicable to the insulated wire for coil, and preferably has low resistance and good conductivity, for example, a conductivity of 70% IACS or more. By using such a central conductor 1, even if a metal layer 2, which will be described later, is provided on the outer periphery, the conductive wire of the entire insulated wire for high frequency coil can be made 60% IACS or more. In the case of a copper alloy or an aluminum alloy, the alloy composition is adjusted so that the high-frequency coil insulated wire 20 has a desired electrical conductivity (an electrical conductivity arbitrarily selected from 60% IACS or higher). Therefore, various alloys can be selected in order to satisfy the desired electrical conductivity, and the content of the metal component contained can also be arbitrarily selected in consideration of the high frequency characteristics. The electrical conductivity can be calculated according to the method for measuring volume resistivity and electrical conductivity of non-ferrous metal materials described in JIS H-0505.

Although the diameter of the central conductor 1 is not particularly limited, it is, for example, within the range of about 0.02 to 0.8 mm. In the present invention, as will be described later, a wire (also referred to as a central conductor wire) having a length of about 6.0 to 12.0 mm is prepared, and a copper-iron alloy tape for a metal layer is attached to the outer periphery of the wire. After that, if necessary, heat treatment is performed to remove processing strain, or by drawing while removing, the center conductor 1 having the above wire diameter and the metal layer 2 provided on the outer periphery are provided. It can be a wire rod.

(metal layer)
The metal layer 2 is provided on the outer periphery of the central conductor 1 and is composed of copper and an iron group element. Copper acts to facilitate the formation of the compound layer 3 to be described later and to improve the solderability. It acts to suppress the increase in resistance. Therefore, the metal layer 2 composed of copper and an iron group element easily forms a compound layer 3, and acts to suppress corrosion of the iron group element and increase corrosion resistance (mainly the action of copper), and solder It acts to ensure adhesion (mainly the action of copper) and acts to improve high-frequency characteristics (mainly the action of iron group elements).

The metal layer 2 is preferably an alloy of copper and an iron group element, for example, one selected from a copper-iron alloy, a copper-nickel alloy, and a copper-cobalt alloy. A copper-iron alloy is particularly preferred. The content of the iron group element contained in the metal layer 2 is not particularly limited, but is preferably within the range of 10 to 50% by mass. The remainder is copper content, which includes trace amounts of unavoidable impurities. By containing the iron group element within this range, the magnetic shielding effect of the metal layer 2 can remarkably increase the Q value after forming the coil. Within this range, if the content of the iron group element, which is a ferromagnetic component, is contained in a relatively large amount, it is advantageous in terms of the magnetic shield effect. On the other hand, if the content of the iron group element is small, the magnetic shield effect may not be sufficient. In that case, the thickness of the metal layer 2 is increased to improve the coverage. By increasing the magnetic shielding effect, the magnetic shielding effect may be enhanced.

The iron group element content can be qualitatively and quantitatively analyzed by ICP emission spectrometry. Elements other than the iron group elements are not included as those that directly affect the effects of the present invention, and Sn, Pb, As, Ag, Sb, etc. are included as so-called unavoidable impurities. To some extent.

Although the method for forming the metal layer 2 is not particularly limited, it is preferably formed using a tape for forming a metal layer. Specifically, the metal layer forming tape is wrapped around the central conductor 1 in the axial direction, and the metal layer forming tape is made into a cylindrical composite material by brazing or welding. Subsequently, the composite material is drawn using a wire drawing die, and the central conductor 1 and the metal layer forming tape are cold-pressed to form a composite conductor in which the metal layer 2 is provided on the central conductor 1. can be Such a composite conductor is drawn and processed to a predetermined wire diameter. In addition, the diameter of the wire may be reduced while removing or alleviating processing strain by performing heat treatment as necessary. Furthermore, it can be made into a rectangular wire by rolling.

In the compound layer-covered wire 10 finally obtained, the thickness of the metal layer 2 is such that the ratio of the cross-sectional area of the metal layer 2 to the total cross-sectional area of the compound layer-covered wire 10 is within a range of 10 to 50%. A certain amount of metal layer forming tape is used. By setting the cross-sectional area ratio of the metal layer 2 within the above range, the saturation magnetic flux density does not become too small, and the AC resistance is less likely to increase. In addition, the DC resistance does not increase due to the decrease in electrical conductivity, the Q value can be improved, and the size of the coil can be reduced. A preferable range within the range of 10 to 50% is designed according to the final wire diameter of the compound layer-coated wire 10 and the high-frequency coil insulated wire 20, the frequency used in the coil, the direct current resistance, and the like.

The thickness of the metal layer 2 may be such that the cross-sectional area ratio of the metal layer 2 to the total cross-sectional area of the compound layer-coated wire 10 is within the range of 10 to 50%. It depends on the wire diameter of 1. Such thickness can be controlled by arbitrarily selecting the thickness of the metal layer forming tape that wraps the central conductor 1 .

Since the metal layer 2 contains an iron group element, it acts to prevent solder corrosion during soldering. However, the fact that an iron group element prevents solder corrosion means that an intermetallic compound between tin and an iron group element in the solder is difficult to form. On the other hand, since the metal layer 2 contains more copper than iron group elements, it has good solderability due to the action of the copper component.

(compound layer)
The compound layer 3 is provided on the outer periphery of the metal layer 2 and formed by forming a complex with the constituent components of the metal layer 2 . The compound layer 3 is formed by bringing a compound capable of forming a complex with the constituent components of the metal layer 2 into contact with the metal layer 2 .

Examples of compounds include imidazole and amine organic acid salts. Among them, imidazole represented by Chemical Formula 1 below is preferable. This imidazole is available commercially. When imidazole reacts with copper forming the metal layer 2, a copper imidazole complex represented by chemical formulas 2 and 3 below is formed. The compound layer 3 is preferably a film formed of such a copper-imidazole complex.

The thickness of the compound layer 3 is preferably within the range of 0.05-0.5 μm. Since the compound layer 3 is provided with a thickness within this range, oxidation of the central conductor 1 and the metal layer 2 can be prevented, and excellent solder wettability can be achieved. Furthermore, since the film thickness can be reduced to about 1/10 of that of the conventional enamel film, the diameter of the final insulated wire 20 can be reduced and the cross-sectional area can be reduced by about 15%, which contributes to miniaturization of the coil. can contribute. In addition, since the compound layer 3 is not as thick as a conventional enamel film, there is an extremely small amount of burnt residue at the time of soldering, and there is also the advantage that problems due to burnt residue at solder joints are less likely to occur. Conventionally, it is possible to solder enamel films with low heat resistance, such as urethane, as they are. there were. In addition, in the case of materials such as polyimide, which have a high heat resistance temperature, it is necessary to remove the enamel film by chemicals or machining before soldering, which requires a large amount of processing man-hours. Since the compound layer 3 has such a small thickness, the insulated wire 20 is formed by covering the outer periphery of the twisted wire 11 obtained by twisting the compound layer-covered wires 10 covered with the thin compound layer 3 with the insulating layer 4 described later. can be made smaller.

The compound layer 3 is preferably composed of a material that decomposes at the soldering temperature. The soldering temperature at this time is any temperature within the range of 200 to 450.degree. Both of the imidazole and the amine organic acid salt described above decompose at the soldering temperature, so that the final terminal treatment can be performed by soldering. Moreover, by changing the enamel film to the compound layer 3, the film thickness can be reduced as described above, and the energy required for decomposition of the film can be reduced. Therefore, the solder immersion time can be shortened, and there is no wire thinning of the conductor, leading to improvement in reliability of bonding.

The compound layer 3 can be formed by contacting the compound solution and the metal layer 2 and drying them. As the contacting means, a wire composed of "1 central conductor and 2 metal layers" may be immersed in the compound solution, or the compound solution may be applied or sprayed onto the wire. Drying is performed to remove the solvent (eg, water, organic solvent, etc.) that constitutes the compound solution. Such a step of forming the compound layer 3 does not require a conventional baking step, and the number of man-hours can be reduced. Further, after applying the above contact means, the compound layer 3 can be formed by drying or the like. In addition, while the contacting means such as application is being performed, a twisting step can be provided immediately after. It can be formed with a simpler device than a film, and the stranded wire 11 can be produced very efficiently in a short time. Therefore, the insulated wire 20 using it can be provided at a low cost.

Moreover, the metal layer 2 with which the compound contacts is a single layer composed of copper and an iron group element, and is formed using a tape for forming a metal layer. there is Therefore, compared with conventional magnetic plated wires in which cracks or the like are likely to exist in the ferromagnetic layer, there is an advantage that corrosion is less likely to occur, and good solderability can be ensured.

In addition, since the metal layer 2 is a uniform single layer without cracks, etc., the compound layer 3 is formed with a thin thickness, unlike a plated wire that is likely to have cracks and requires a thick insulating film (enamel film). That's enough. As described above, the thin compound layer 3 is desirable from the viewpoint of downsizing and solderability.

(stranded wire)
As shown in FIGS. 2 and 3, the stranded wire 11 is obtained by twisting a plurality of compound layer-covered wires 10 covered with the compound layer 3 . Twisting may include bunch twisting, concentric twisting, and the like, and the twisted wire may be subjected to compression processing to further reduce the outer diameter. The twist pitch and the like are set arbitrarily and are not particularly limited. Also, the number of compound layer-coated wires 10 is not particularly limited, and can be arbitrarily set according to required product specifications and coil specifications.

(insulating layer)
As shown in FIGS. 2 and 3, the insulating layer 4 is coated on the outer periphery of the stranded wire 11, and may be formed of, for example, an insulating coating film, an insulating extruded resin, an insulating tape, or a combination thereof. preferable. The insulating layer 4 may be composed of a material that decomposes at the soldering temperature, in which case the terminal can be processed by soldering.

As a constituent material of the insulating layer 4, various resins constituting an insulated wire can be used. For example, resins capable of forming a solderable insulating layer include thermosetting resins such as polyurethane resins, polyester resins, and polyesterimide resins. Among these, polyurethane resins and polyester resins are preferred. Also, although solderability is not possible, polyphenyl sulfide (PPS), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), fluorinated resin Copolymer (perfluoroalkoxy fluorine resin: PFA), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyamide (PA), polyphenyl sulfide (PPS), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP) etc. can also be mentioned.

The insulating layer 4 may be a single layer or a laminate as long as it is an insulating coating film, an insulating extruded resin, an insulating tape, or the like. When the insulating layer 4 is laminated, two or more of the same or different thermosetting resin layers may be provided, or a thermoplastic resin layer may be laminated on the thermosetting resin layer. Moreover, the thermoplastic resin layer may be laminated by combining tape winding and extrusion.

As a method of forming the insulating layer 4, the composition when forming the insulating layer 4 with a thermosetting resin material contains a cross-linking agent and a solvent in addition to the thermosetting resin material. Moreover, various additives are contained as needed. Those cross-linking agents, solvents and additives are not particularly limited. The insulating layer 4 is formed by applying a forming composition, by winding a tape, or by extrusion molding.

The thickness of the insulating layer 4 is not particularly limited regardless of whether it is a single layer or a laminated layer, but it is usually preferably 20 μm or more. If the thickness of the insulating layer 4 is less than 20 μm, it may be too thin to ensure sufficient insulation.

(Insulated wire for high frequency coil)
The obtained high-frequency coil insulated wire 20 is used for coils (reactors, inductors, choke coils, noise filters, IH heaters, power transformers, etc.). This high-frequency coil insulated wire 20 can exhibit stable high-frequency characteristics, and is a small-diameter high-frequency coil insulated wire that can be manufactured at low cost.

The electrical conductivity of the insulated wire for high frequency coil is preferably 60%IACS or more. The conductivity varies depending on the type of coil used, and it is preferable that the desired conductivity is in the range of 60% IACS or more. In particular, the diameter of the wire can be easily reduced, and good shielding properties can be obtained. Furthermore, by using a stranded wire, a litz wire, or the like as an insulated wire, it is possible to reduce the size and increase the frequency of the coil.

[Electronic parts]
FIG. 4 shows an example of a coil component 30 manufactured from the insulated wire 20 for high frequency coils according to the present invention. Since the coil component 30 uses the insulated wire 20 having a small outer diameter, it is possible to reduce the size of the coil and increase the occupation ratio of the insulated wire per unit volume.

4A is a cross-sectional view of the insulated wire 20 according to the present invention wound around a bobbin 21, and FIG. 4B is a cross-sectional view of a conventional insulated wire 22 having a large outer diameter wound around the bobbin 21. FIG. be. As shown in FIGS. 3A and 3B, when the insulated wire is wound with the same number of turns on a bobbin of the same size, the winding thickness a when the insulated wire 20 according to the present invention is wound is greater than that of the conventional one. It becomes smaller than the winding thickness b when the insulated wire 22 is wound.

The present invention will be described in more detail below with reference to examples and comparative examples. In addition, this invention is not limited by this.

[Example 1]
A copper-iron alloy tape with a thickness of 0.25 mm containing 50% by mass of iron is wrapped around the outer circumference of a tough pitch copper wire with a diameter of 8.0 mm, the joint is welded, and the cross-sectional area ratio is 10 by die drawing. A strand of copper-iron alloy-coated copper wire (diameter 7.0 mm) having a metal layer 2 serving as a % coating was produced. In the subsequent wire drawing process, heat treatment and cold working were repeated to obtain strands having a diameter of 0.1 mm, and 21 strands of this strand were prepared. 21 strands were immersed in an imidazole aqueous solution at a speed of 50 m/min for 0.3 seconds, washed with water, and dried at 130° C. to form a compound layer 3 having a thickness of 0.1 μm. was made. The compound layer-covered strands 10 were twisted as they were at a pitch of 18 mm to produce a twisted wire 11 with a diameter of 0.53 mm. As the aqueous imidazole solution, an aqueous solution containing about 5% by mass of imidazole, 10% by mass of acetic acid, and about 0.5% by mass of other additives was used. Subsequently, three layers of PET tape were wrapped around the twisted wire 11 to form an insulating layer 4 having a thickness of 85 μm. Thus, the insulated wire 20 of Example 1 having a diameter of about 0.70 mm was produced.

[Example 2]
An insulated wire 20 of Example 2 was produced in the same manner as in Example 1, except that a copper-iron alloy tape containing 10% by mass of iron and having a thickness of 0.25 mm was used.

[Example 3]
An insulated wire 20 of Example 3 was produced in the same manner as in Example 1, except that a copper-nickel alloy tape containing 10% by mass of nickel and having a thickness of 0.25 mm was used.

[Example 4]
An insulated wire 20 of Example 4 was produced in the same manner as in Example 1, except that a copper-cobalt alloy tape containing 10% by mass of cobalt and having a thickness of 1.65 mm was used. The copper-cobalt alloy-coated copper wire has a metal layer 2 covering 50% of the cross-sectional area.

[Example 5]
Using the same copper-cobalt alloy tape containing 10% by mass of cobalt as in Example 4 and having a thickness of 1.65 mm, a copper-cobalt alloy-coated copper wire having a metal layer 2 covering 50% in cross-sectional area ratio, and further 21 copper-cobalt alloy-coated copper wires were immersed in an imidazole aqueous solution at a speed of 10 m/min for 1.5 seconds, washed with water, and dried to form a compound layer-coated wire provided with a compound layer 3 having a thickness of 0.3 μm. An insulated wire 20 of Example 5 was produced in the same manner as in Example 4, except that 10 was formed.

[Example 6]
A copper-iron alloy tape with a thickness of 1.25 mm containing 10% by mass of iron is wrapped along the outer periphery of a silver-containing copper wire containing 2% by mass of silver with a diameter of 8.0 mm, the joint is welded, and a die is used. A strand of copper-iron alloy-coated copper wire (8.0 mm in diameter) having a metal layer 2 with a 30% cross-sectional area ratio was prepared. After the subsequent wire drawing process, the insulated wire 20 of Example 6 was produced in the same manner as in Example 1.

[Example 7]
A copper-iron alloy tape with a thickness of 1.25 mm containing 10% by mass of iron is wrapped along the outer circumference of an oxygen-free copper wire with a diameter of 8.0 mm, the joint is welded, and the cross-sectional area ratio is obtained by drawing with a die. A strand of copper-iron alloy coated copper wire (diameter 8.0 mm) having a metal layer 2 covering 30% was produced. After the subsequent wire drawing process, the insulated wire 20 of Example 7 was produced in the same manner as in Example 1.

[Comparative Example 1]
Tough-pitch copper wire with a diameter of 8.0 mm was die-drawn as it was without applying a copper-iron alloy tape or the like to prepare a tough-pitch copper wire with a diameter of 7.0 mm. Other than that, in the same manner as in Example 1, an insulated wire of Comparative Example 1 was produced.

[Comparative Example 2]
In the same manner as in Comparative Example 1, a tough pitch copper wire having a diameter of 7.0 mm was produced, and 21 tough pitch copper wires were immersed in an aqueous imidazole solution at a speed of 50 m / min for 0.1 second, washed with water, and dried. Thus, a compound layer-coated wire 10 provided with a compound layer 3 having a thickness of 0.03 μm was formed. Other than that, in the same manner as in Comparative Example 1, an insulated wire of Comparative Example 2 was produced.

[Comparative Example 3]
Using the same copper-iron alloy tape containing 50% by mass of iron as in Example 1 and having a thickness of 0.25 mm, a copper-iron alloy coated copper wire having a metal layer 2 covering 10% in cross-sectional area ratio, and further, 21 copper-iron alloy-coated copper wires were immersed in an imidazole aqueous solution at a speed of 50 m/min for 0.1 second, washed with water, and dried to form a compound layer-coated wire provided with a compound layer 3 having a thickness of 0.03 μm. 10 was formed. Except for this, an insulated wire of Comparative Example 3 was produced in the same manner as in Example 1.

[Evaluation of high-frequency AC resistance]
Using the insulated wires prepared in Examples 1 to 7 and Comparative Examples 1 to 3, 8 turns were wound on a bobbin with a diameter of 12 mm to form a coil shape, and the coil was measured at 500 kHz with a HP4284A precision LCR meter manufactured by Agilent Technologies. was evaluated.

Table 1 shows the results. From the results in Table 1, the insulated wires 20 of Examples 1 to 7 show a higher Q value than Comparative Example 1, confirming that they can be used as insulated wires that suppress an increase in AC resistance in a high frequency region.

REFERENCE SIGNS LIST 1 center conductor 2 metal layer 3 compound layer 4 insulation layer 5 insulation layer 10 compound layer coated wire 11 stranded wire 20 insulated wire for high frequency coil 21 bobbin 22 conventional insulated wire with a large outer diameter 30 coil component

Claims (7)

A central conductor, a metal layer composed of copper and an iron group element provided around the central conductor, and a compound layer provided around the metal layer and formed by forming a complex with a constituent metal of the metal layer. A high-frequency coil insulated wire having a stranded wire in which a plurality of compound layer-coated wires are twisted together, and an insulating layer provided on the outer periphery of the stranded wire,
The thickness of the metal layer is such that the cross-sectional area ratio of the metal layer to the total cross-sectional area of the compound layer-covered wire is within a range of 10 to 50%,
An insulated wire for a high-frequency coil, wherein the compound layer has a thickness in the range of 0.05 to 0.5 μm. 2. The insulated wire for a high frequency coil according to claim 1, wherein said compound layer is composed of a material that decomposes at a soldering temperature. 3. The insulated wire for a high frequency coil according to claim 1, wherein said compound layer is a copper imidazole compound layer formed by forming a complex with copper constituting said metal layer. The insulated wire for high-frequency coils according to any one of claims 1 to 3 , wherein said insulating layer is selected from an insulating coating, an insulating extruded resin, an insulating tape, and combinations thereof. The insulated wire for high-frequency coils according to any one of claims 1 to 4 , wherein the central conductor is selected from tough pitch copper, oxygen-free copper, silver-containing copper, tin-containing copper, copper-clad aluminum, aluminum, and aluminum alloys. . The insulated wire for high-frequency coils according to any one of claims 1 to 5 , wherein said metal layer is selected from a copper-iron alloy, a copper-nickel alloy and a copper-cobalt alloy. The content of one or more iron group elements selected from iron, nickel and cobalt contained in the metal layer is in the range of 5 to 50% by mass, according to any one of claims 1 to 6 . insulated wires for high frequency coils.

Images