JP7109938B2 - High-frequency coil wire, insulated wire, and method for manufacturing high-frequency coil wire - Google Patents

Description

The present invention relates to a wire and an insulated wire for a high frequency coil, and more specifically, it is used as a coil using an insulated wire in the high frequency field using power semiconductors such as motors, inverters, and contactless power supply, and exhibits stable high frequency characteristics. The present invention relates to providing a thin high-frequency coil wire and an insulated wire that can be manufactured at low cost.

Patent Literature 1 proposes a coil wire that can reduce conductor loss caused by an alternating magnetic field from the outside. This technology has at least one metal selected from copper, copper alloys, aluminum and aluminum alloys, has a conductor with a cross-sectional area of 0.4 mm ² or more, and has an iron-based material containing Fe, and the conductor and a magnetic layer formed on the outer periphery of the conductor, wherein the ratio of the cross-sectional area of the magnetic layer to the combined cross-sectional area of the conductor and the magnetic layer is 3% or more and 40% or less.

Patent Literature 2 proposes a coil wire that can reduce eddy currents due to a surrounding alternating magnetic field to form a low-loss coil. This technology is a coil wire comprising a conductor wire and a magnetic layer formed of a magnetic material on the outer periphery of the conductor wire, wherein the magnetic layer comprises a steel-containing layer formed of carbon steel, preferably is that the total content of carbon, phosphorus and silicon in the carbon steel is more than 0 and 0.3% by mass or less.

Patent Literature 3 proposes a coil wire that can reduce eddy currents caused by surrounding alternating magnetic fields to form a low-loss coil. This technique is a coil wire comprising a conductor wire and a magnetic layer formed of a magnetic material on the outer periphery of the conductor wire, wherein the magnetic layer extends in the circumferential direction in a cross section orthogonal to the axial direction of the conductor wire. In other words, the non-uniform layer has a thick portion and a thin portion having different thicknesses, and the ratio of the maximum thickness of the thick portion to the minimum thickness of the thin portion is 1.1 or more.

In Patent Document 4, an electric wire that can shield an external magnetic field that tries to enter the interior, can reduce eddy current due to the external magnetic field that has entered the interior without being completely shielded, and can suppress loss due to the proximity effect. is proposed. This technique comprises a central conductor made of Al or an Al alloy, a covering layer made of copper covering the central conductor, and a ferromagnetic layer covering the covering layer and shielding an external magnetic field. The thickness is 0.04 μm to 14 μm, the total diameter of the central conductor and the covering layer is 0.05 mm to 0.4 mm, and the cross-sectional area of the central conductor is that of the total cross-sectional area of the central conductor and the covering layer. 85% to 95%.

JP 2016-46522 A JP 2017-37896 A JP 2017-37897 A WO2013/42671

High-frequency characteristics are greatly affected by the skin effect. Therefore, generally, a single wire having a diameter within the skin depth of the frequency to be used is preferably used. Furthermore, in order to secure the total cross-sectional area, a litz wire or the like, which is obtained by twisting a plurality of such single wires, is used to suppress the increase in resistance and reduce the high-frequency AC resistance. High-frequency coils in recent years are required to be more compact and have higher performance, and litz wires and stranded wires are preferably used particularly in the high-frequency band of 80 kHz to several MHz. However, since litz wires and stranded wires use a plurality of component wires, further reduction in the diameter of each component wire is required.

The technologies of Patent Documents 1 to 3 have a cross-sectional area of 0.4 mm ² or more (corresponding round wire diameter is 0.72 mm or more), and are suitable for high-frequency coils in recent years where miniaturization and high performance are required. unsuitable. For example, in a 0.72 mm copper wire, the depth range of current flow is 0.066 mm at 1 MHz, 0.094 mm at 500 kHz, and 0.209 mm at 100 kHz, and the frequency bands used are 1 MHz, 500 kHz, and 100 kHz. Then, only 1%, 2%, and 9% of the total cross-sectional area are the ranges through which the current flows, respectively. On the other hand, although the document does not describe reduction in wire diameter, if the wire diameter is reduced, iron-based materials (mainly permalloy, carbon steel, etc.) are difficult to wire draw, and in order to draw wire, , it is necessary to remove the working strain at the time of wire drawing step by step. Heat treatment at 900° C. or higher is required to remove processing strains of ferrous materials and the like. However, copper, which is the central conductor, is likely to cause over-annealing and hydrogen embrittlement due to the heat treatment, which rather impedes the workability of the central conductor. difficult.

In the technique of Patent Document 4, the central conductor (Al, Al alloy) and the ferromagnetic layer (sendust, permalloy, etc.) have greatly different heat treatment conditions for removing processing strain, so strain removal by heat treatment is difficult. . Therefore, a method of drawing the center conductor to a desired diameter and then plating the ferromagnetic layer is conceivable. However, the plating of the ferromagnetic layer is difficult to manage, including adjusting the concentration of trace additives, unlike the case of clad processing in which ferromagnetic tapes are fitted and welded together. The component composition ratio tends to vary, making it difficult to obtain good magnetic permeability and stable high-frequency characteristics.

In consideration of the above problem, the applicant of the present application has produced a product in which iron and Ni are plated in order on the central conductor after wire drawing to a predetermined wire diameter, but the productivity is insufficient. There are drawbacks. In addition, when a wire is drawn to a predetermined diameter and plated with iron, the iron plating layer is likely to crack due to the strong electrodeposition stress in the tensile direction. The thickness is about 2 μm, and it is difficult to plate with a thickness greater than that. On the other hand, in a thin iron plating layer having a thickness of 1 μm or less, the saturation magnetic flux density is small, so the ability to suppress the proximity effect in a high frequency band is low. Specifically, the magnetic flux that cannot be fully concentrated in the iron plating layer is saturated and permeates the inside of the conductor, generating eddy currents. .

The present invention was made to solve the above problems, and its purpose is to provide coils (reactors, inductors, To provide a thin high-frequency coil wire and an insulated wire that can be used as a choke coil, noise filter, IH heater, power transformer, etc., can exhibit stable high-frequency characteristics, and can be manufactured at low cost.

A wire rod for a high-frequency coil according to the present invention is characterized by having a central conductor made of copper or a copper alloy and a copper-iron alloy layer provided around the outer periphery of the central conductor.

According to the present invention, in the high-frequency coil wire having the copper-iron alloy layer provided on the outer periphery of the central conductor made of copper or copper alloy, the heat treatment conditions for removing the working strain of the copper-iron alloy layer are the same as the heat treatment conditions for the central conductor. Or because it is almost the same, it is excellent in wire drawing workability. Therefore, even when strain is removed by wire drawing for wire thinning, the center conductor is unlikely to become hydrogen embrittlement or over-annealed. As for high-frequency characteristics, the copper-iron alloy layer provided on the outer periphery exhibits a good shielding effect, so that an increase in high-frequency resistance can be suppressed, which is advantageous for miniaturization of the coil. Such a high-frequency coil wire can exhibit stable high-frequency characteristics and can be made into a thin wire at low cost.

In the high-frequency coil wire according to the present invention, it is preferable that the iron content in the copper-iron alloy layer is in the range of 5 to 50% by mass.

In the high-frequency coil wire according to the present invention, it is preferable that the cross-sectional area ratio of the copper-iron alloy layer to the total cross-sectional area of the high-frequency coil wire is in the range of 5 to 50%. According to the present invention, 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 reduction in the Q value can be prevented, and the miniaturization of the coil can be realized.

In the high-frequency coil wire according to the present invention, the electrical conductivity is preferably 60%IACS or more.

In the high-frequency coil wire according to the present invention, it is preferable that the material of the central conductor is selected from tough pitch copper, oxygen-free copper, silver-containing copper, and tin-containing copper.

In the high-frequency coil wire according to the present invention, it is preferable that a compound layer exists on the interface between the central conductor and the copper-iron alloy layer.

An insulated wire according to the present invention is characterized in that it has the high-frequency coil wire according to the present invention, and an insulating layer is formed on the outer periphery of the copper-iron alloy layer that constitutes the high-frequency coil wire.

According to the present invention, it is possible to provide a small-diameter high-frequency coil wire and an insulated wire that can be used as a coil using an insulated wire, exhibit stable high-frequency characteristics, and can be manufactured at low cost. In particular, by forming a composite conductor in which a copper-iron alloy layer is provided on the outer periphery of the central conductor, it is possible to easily reduce the wire diameter and obtain good shielding properties. 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.

1 is a cross-sectional view showing an example of a high-frequency coil wire according to the present invention; FIG. It is a sectional view showing an example of an insulated wire concerning the present invention.

A high-frequency coil wire and an insulated wire 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.

[Wires for high frequency coils]
A high-frequency coil wire 10 according to the present invention, as shown in FIG. The high-frequency coil wire 10 is excellent in drawing workability because the heat treatment conditions for removing the working strain of the copper-iron alloy layer 2 are the same or substantially the same as the heat treatment conditions of the central conductor 1 . Therefore, even when the strain is removed by wire drawing for thinning, the central conductor 1 is unlikely to become hydrogen embrittlement or over-annealed. As for the high-frequency characteristics, the copper-iron alloy layer 2 provided on the outer periphery exhibits a good shielding effect, so it is possible to suppress an increase in high-frequency resistance, which is advantageous for miniaturization of the coil. Such a high-frequency coil wire 10 can exhibit stable high-frequency characteristics, and can be manufactured as a thin wire at low cost.

The constituent elements of the high-frequency coil wire will be described below.

(Center conductor)
The central conductor 1 is made of copper or copper alloy. 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 it is tough pitch copper or oxygen-free copper can be determined by a hydrogen embrittlement test in accordance with JIS H-3510. The contained elements can be measured by ICP emission spectrometry for qualitative and quantitative analysis.

These central conductors 1 preferably have good conductivity with a low resistance of 70% IACS or more. By using such a central conductor 1, even when a copper-iron alloy layer 2, which will be described later, is provided on the outer periphery, the overall electrical conductivity of the high-frequency coil wire can be increased to 60% IACS or higher. In addition, in copper alloys such as copper-silver alloys and copper-tin alloys, the alloy composition is adjusted so that the high-frequency coil wire 10 has a desired conductivity (a conductivity arbitrarily selected from 60% IACS or higher). be. Therefore, various copper 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 strand (also referred to as a center conductor strand) is prepared within the range of about 6.0 to 12.0 mm, a copper-iron alloy tape is provided on the outer periphery of the strand, After that, the high-frequency coil wire 10 having the central conductor 1 having the above wire diameter can be obtained by performing a wire drawing process after or while removing processing strain by heat treatment as necessary.

(copper-iron alloy layer)
The copper-iron alloy layer 2 is provided on the outer circumference of the central conductor 1 . The heat treatment conditions for removing the processing strain of the copper-iron alloy layer 2 are set according to the treatment method in continuous heat treatment such as in-line or batch heat treatment, but in the example of batch heat treatment, 400 ° C., 2 time, which is the same or nearly the same as 350° C. for 2 hours, which is an example of batch-type heat treatment of the center conductor 1 . Therefore, processing strains in both the central conductor 1 and the copper-iron alloy layer 2 can be easily removed or relaxed under such heat treatment conditions. As a result, unlike the conventional technology, hydrogen embrittlement and over-annealing of the central conductor due to different heat treatment conditions for the central conductor and the ferromagnetic layer do not occur, and excellent wire drawing workability for reducing the diameter is achieved. It is possible to achieve efficient manufacturing and reduce manufacturing costs.

When the high-frequency coil wire 10 provided with the copper-iron alloy layer 2 is used to form a high-frequency coil, the copper-iron alloy layer 2 provided on the outer periphery exhibits a good shielding effect. As a result, the copper-iron alloy layer 2 acts to suppress an increase in high-frequency resistance (AC resistance) and improve high-frequency characteristics. is advantageous for the production of

The iron content in the copper-iron alloy layer 2 is preferably in the range of 5-50% by mass. By setting the iron content within this range, particularly excellent high-frequency characteristics can be obtained. The lower limit of the content is set in consideration of the high frequency resistance (AC resistance), and the upper limit is set in consideration of the DC resistance (conductivity). Iron content can be qualitatively and quantitatively analyzed by ICP emission spectroscopy. Elements other than iron are not included as those that directly affect the effects of the present invention, and so-called unavoidable impurities such as Sn, Pb, As, Ag, and Sb may be included. degree.

Although the method of forming the copper-iron alloy layer 2 is not particularly limited, it is preferably formed using a copper-iron alloy tape. Specifically, the copper-iron alloy tape is wrapped around the center conductor 1 in the axial direction, and the copper-iron alloy 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 copper-iron alloy tape are cold-pressed to form a composite in which the copper-iron alloy layer 2 is provided on the central conductor 1. It can be a conductor. 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.

The thickness of the copper-iron alloy layer 2 is such that, in the finally obtained high-frequency coil wire 10, the ratio of the cross-sectional area of the copper-iron alloy layer to the total cross-sectional area of the high-frequency coil wire 10 is within a range of 5 to 50%. A copper-iron alloy tape with a degree of By setting the cross-sectional area ratio of the copper-iron alloy layer 2 within the above range, the saturation magnetic flux density does not become too small, and the AC resistance hardly increases. In addition, the DC resistance does not increase due to the decrease in electrical conductivity, the reduction in the Q value can be prevented, and the miniaturization of the coil can be realized. A preferable range within the range of 5 to 50% is designed according to the final wire diameter of the high-frequency coil wire, the frequency used in the coil, the DC resistance, and the like.

The thickness of the copper-iron alloy layer 2 varies depending on the wire diameter of the central conductor 1, so it cannot be said unconditionally. When provided, the thickness is increased, and when the copper-iron alloy layer 2 is provided at a stage where the central conductor 1 is relatively thin, the thickness is reduced. Such thickness can be controlled by arbitrarily selecting the thickness of the copper-iron alloy tape wrapping the central conductor 1 .

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

(compound layer)
A compound layer 3 is preferably present at the interface between the central conductor 1 and the copper-iron alloy layer 2 . This compound layer 3 is a compound of an element in copper or a copper alloy and iron, and examples thereof include CuFe and Cu2Fe. The presence of such a compound layer 3 is advantageous because it can improve the adhesion and, as a result, improve the drawability. The compound layer 3 is mainly likely to be formed by heat treatment applied to remove or relax processing strain, and its thickness is not particularly limited because it varies depending on the heat treatment conditions. 0 μm. In addition, the fact that the compound layer 3 is a compound is different from that which exhibits a single physical property as an alloy, and each physical property (physical property: linear expansion coefficient, thermal conductivity, etc., ) coexist. The fact that the compound layer 3 is not an alloy but a compound can be evaluated by an X-ray diffraction method or the like.

The heat treatment may be performed for the purpose of removing processing strain generated after working, or the heat treatment may be performed using the heat of an annealing furnace when coating the enameled wire. The heat treatment here may be any of them, and when the insulating layer 4 is not provided, the heat treatment may be performed continuously or batchwise in a heat treatment furnace in air or in an inert gas. In the case of enamel coating, the heat treatment may be continuously performed in an annealing furnace in the baking process. In these heat treatments, the compound layer 3 can be formed by controlling the temperature and time. The heat treatment conditions vary depending on whether the treatment is continuous or batch treatment and are not particularly limited.

(others)
A plating layer (not shown) may be provided on the outer periphery of the copper-iron alloy layer 2 within a range that does not hinder the effects of the present invention, for example, to make soldering easier or to prevent solder corrosion. good. Although the thickness is not particularly limited, it is preferably in the range of 0.02 to 1.0 μm. As for the type of plating layer, silver plating, gold plating, nickel plating, etc. are preferable for the purpose of improving solderability, and nickel plating, etc. are preferable for the purpose of preventing solder corrosion. The plating method, plating solution composition, plating conditions, plating thickness, etc. are arbitrarily set.

(Wire for high frequency coils)
The obtained high-frequency coil wire 10 is used for coils (reactors, inductors, choke coils, noise filters, IH heaters, power transformers, etc.) using insulated wires in high-frequency fields that use power semiconductors such as motors, inverters, and contactless power supply. ). This high-frequency coil wire 10 can exhibit stable high-frequency characteristics, and is a small-diameter high-frequency coil wire that can be manufactured at low cost.

The electrical conductivity of the high-frequency coil wire is preferably 60% IACS or higher. 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.

[Insulated wire]
As shown in FIG. 2, an insulated wire 20 according to the present invention has the high-frequency coil wire 10 according to the present invention. is formed. Since the constituent elements of the high-frequency coil wire 10 have already been explained, the rest will be explained below.

(insulating layer)
The insulating layer 4 is provided on the outer periphery of the copper-iron alloy layer 2, as shown in FIG. By providing the insulating layer 4, the wire material 10 for high-frequency coils is useful as electric wires for various high-frequency coils and high-frequency coils (stranded wires, insulated wires in which the outer circumference of assembled wires is integrated with an insulating coating, etc.). Available. The insulating layer 4 is not particularly limited, and conventionally known layers can be applied. For example, it is provided as an insulating coated film, an insulating extruded resin, an insulating tape, or a combination thereof.

Examples of materials for the insulating layer 4 include thermosetting resins such as polyurethane resins, polyester resins, and polyesterimide resins. In addition, polyphenyl sulfide (PPS), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy fluororesin: PFA), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyamide (PA), polyphenyl sulfide (PPS), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP), etc. .

The insulating layer 4 may be a single layer or a laminate. When the insulating layer 4 is of laminated form, the same or different resin layers as described above can be provided. For example, after providing an insulating layer made of urethane resin, a bonding layer made of nylon may be provided on the outer periphery of the insulating layer to form the insulating layer 4 composed of "insulating layer + bonding layer". 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 3.0 μm or more. Also, the insulated wire 20 may be used as a single wire, or may be used as a litz wire, a circular compression wire, or the like. Alternatively, after the litz wire is produced, PFA may be melt-extruded to further form an insulating coating layer on the outer periphery of the litz wire.

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]
Tough-pitch copper (abbreviated as TPC) with a diameter of 8.0 mm and 101% IACS was used as the strand for the central conductor. Next, a copper-iron alloy tape having a width of 28 mm, a thickness of 0.15 mm and an Fe content of 5% by mass was prepared. This copper-iron alloy tape was axially wrapped around the central conductor wire, and welded to produce a cylindrical composite material with a coverage of 50%. Thereafter, the composite material was drawn using a wire drawing die, and the central conductor element wire and the copper-iron alloy tape were crimped to form a composite conductor having a diameter of 7.0 mm. This composite conductor was drawn to obtain a high-frequency coil wire 10 having a diameter of 0.1 mm. The heat treatment was performed in-line at 600 to 800° C. for 0.5 to 3 minutes at respective timings of 2.6 mm, 0.8 mm, and 0.1 mm in order to relax processing strain. An insulated wire 20 provided with an insulating layer 4 was obtained by applying and baking a polyester-based insulating layer-forming coating material to the outer periphery of the obtained high-frequency coil wire 10 .

[Example 2]
A copper-iron alloy tape with an Fe content of 10% by mass was prepared, wrapped in the axial direction around the central conductor wire, and welded to produce a cylindrical composite material with a coverage of 30%. Otherwise, in the same manner as in Example 1, the high-frequency coil wire 10 and the insulated wire 20 of Example 2 were obtained.

[Example 3]
A copper-iron alloy tape with an Fe content of 30% by mass was prepared, wrapped in the axial direction around the central conductor wire, and welded to produce a cylindrical composite material with a coverage of 30%. Otherwise, in the same manner as in Example 1, the high-frequency coil wire 10 and the insulated wire 20 of Example 3 were obtained.

[Example 4]
A copper-iron alloy tape with an Fe content of 50% by mass was prepared, wrapped in the axial direction around the central conductor wire, and welded to produce a cylindrical composite material with a coverage of 5%. Otherwise, in the same manner as in Example 1, the high-frequency coil wire 10 and the insulated wire 20 of Example 4 were obtained.

[Example 5]
Copper with a diameter of 8.0 mm and containing 2% by mass of 88% IACS silver was used as the strand for the central conductor. Next, the same copper-iron alloy tape having an Fe content of 10% by mass as used in Example 2 was prepared. This copper-iron alloy tape was axially wrapped around the central conductor wire, and welded to produce a cylindrical composite material with a coverage of 30%. After that, in the same manner as in Example 1, the high-frequency coil wire 10 and the insulated wire 20 of Example 5 were obtained.

[Example 6]
Copper with a diameter of 8.0 mm and 80% IACS containing 4% by mass of silver was used as a strand for the central conductor. Otherwise, in the same manner as in Example 5, the high-frequency coil wire 10 and the insulated wire 20 of Example 6 were obtained.

[Example 7]
Copper with a diameter of 8.0 mm and containing 0.3% by mass of tin with 80% IACS was used as the strand for the center conductor. Otherwise, in the same manner as in Example 3, the high-frequency coil wire 10 and the insulated wire 20 of Example 7 were obtained.

[Example 8]
Copper with a diameter of 8.0 mm and 74% IACS containing 3% by mass of tin was used as the strand for the center conductor. Otherwise, in the same manner as in Example 3, the high-frequency coil wire 10 and the insulated wire 20 of Example 8 were obtained.

[Comparative Example 1]
TPC with a diameter of 8.0 mm and 101% IACS was used as a strand for the central conductor, and then drawn using a wire drawing die to obtain a coil wire consisting only of a central conductor with a diameter of 0.1 mm. Note that the heat treatment was performed at 800° C. for 2 minutes at a timing of 2.6 mm in order to relax processing strain. An insulated wire having an insulating layer 4 was obtained by coating and baking a polyester-based insulating layer-forming coating material on the outer circumference of the obtained coil wire.

[Comparative Example 2]
As the strands for the center conductor, those used in Examples 5 to 8 were prepared, respectively, and in the same manner as in Comparative Example 1, coil wires and insulated wires of Comparative Examples 2 to 5 were obtained.

[Measurements and results]
Using the insulated wires of Examples 1 to 8 and Comparative Examples 1 to 5, electrical conductivity, Q value, resistance change rate, and Fe content were measured. The electrical conductivity was calculated by measuring the DC resistance with a YOKOGAWA resistance meter and using the measured value as the electrical conductivity when the copper wire was assumed to be 100%. The Q value was evaluated by making a coil with an insulated wire (enameled wire). A helical coil (number of turns: 22 turns, winding frame diameter: 5.5 mm) was prepared as the coil, and the Q value of the coil at 1 MHz was measured with an impedance analyzer. The rate of change in resistance is a value obtained by dividing the AC resistance by the DC resistance, and evaluated the shielding properties. Fe content was measured by ICP emission spectroscopy. These results are shown in Tables 1 and 2.

From the results in Tables 1 and 2, the high-frequency coil wire 10 using the copper-iron alloy tape had a conductivity about 10% lower than that of the coil wire using no copper-iron alloy tape. It was confirmed that the Q value, which indicates the coil performance at , is increased by about 20%. In addition, the resistance change rate measured was smaller for the high-frequency coil wire 10 using the copper-iron alloy tape than for the coil wire without using the copper-iron alloy tape. From this, it was found that the improvement of the Q value depends on the AC resistance. In addition, it was found that the Fe content has a correlation with the rate of change in resistance.

REFERENCE SIGNS LIST 1 central conductor 2 copper-iron alloy layer 3 compound layer 4 insulating layer 10 high-frequency coil wire 20 insulated wire

Claims (7)

A wire rod for a high-frequency coil for suppressing Q-value reduction obtained by wire drawing,
A central conductor made of copper or a copper alloy and having a diameter of 0.02 to 0.8 mm, and a copper-iron alloy layer provided on the outer periphery of the central conductor , wherein the copper-iron alloy layer has an iron content of 5 to 5. A wire rod for a high-frequency coil, characterized in that the content is within a range of 50% by mass . 2. The high-frequency coil wire according to claim 1 , wherein the cross-sectional area ratio of said copper-iron alloy layer to the total cross-sectional area of said high-frequency coil wire is within a range of 5 to 50%. 3. The high-frequency coil wire according to claim 1, having an electrical conductivity of 60% IACS or more. The high-frequency coil wire according to any one of claims 1 to 3 , wherein the material of said center conductor is any one selected from tough pitch copper, oxygen-free copper, silver-containing copper, and tin-containing copper. The high-frequency coil wire according to any one of claims 1 to 4 , wherein a compound layer is present on the interface between said central conductor and said copper-iron alloy layer. An insulated wire comprising the high-frequency coil wire according to any one of claims 1 to 5 , wherein an insulating layer is formed on the outer periphery of a copper-iron alloy layer constituting the high-frequency coil wire. A method for manufacturing a wire rod for a high-frequency coil for suppressing a reduction in Q value obtained by wire drawing,
The high-frequency coil wire has a central conductor made of copper or a copper alloy and having a diameter of 0.02 to 0.8 mm, and a copper-iron alloy layer provided on the outer periphery of the central conductor. The iron content of is in the range of 5 to 50% by mass,
A copper-iron alloy tape is wrapped around a central conductor made of copper or a copper alloy to produce a tubular composite, the tubular composite is drawn to form a composite conductor, and the composite conductor is drawn at a predetermined timing. A method for producing a wire for a high-frequency coil, characterized in that the wire is drawn while being heat-treated.

Images