JP7146449B2 - Wires and coils for high frequency coils - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric wire and coil for high frequency coils. More specifically, as the frequency of equipment increases, it is a wire that can respond to energy saving and high efficiency of coil parts such as transformers, which are passive parts, and is a high-frequency wire that uses power semiconductors for motors, inverters, contactless power supply, etc. The present invention relates to high-frequency coil wires and coils used as coils (reactors, inductors, choke coils, noise filters, IH heaters, power transformers, etc.) using insulated wires in the field.

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 particular, in recent years, there has been a demand for miniaturization of coil components, and there has also been a demand for a reduction in the diameter of coil wires used.

In response to such a request, Patent Document 1 proposes an electric wire and a coil that reduce loss in a DC superimposed high-frequency circuit, a low-frequency superimposed high-frequency circuit, and the like. This technology consists of two types of insulation coated magnetic material-plated copper wire, in which a magnetic plating layer is formed on the surface of the copper wire and an insulation coating is formed on the surface of the magnetic plating layer, and insulation-coated copper wire, in which an insulation coating is formed on the surface of the copper wire. , is characterized in that the entire cross section is mixed and twisted or gathered without twisting. In addition, this technology can reduce the resistance in direct current or low frequency because the insulation coating magnetic material plated copper wire is arranged on the entire surface, and the magnetic field created by the flowing current is the magnetism of the insulation coating magnetic material plated copper wire. Since it is cut off by the material plating layer and it is difficult to enter the copper wire part, it is possible to suppress the increase in copper loss due to the proximity effect at high frequencies, so it is possible to reduce the loss in DC superimposed high frequency circuits, low frequency superimposed high frequency circuits, etc. It is.

JP 2009-277396 A

The purpose of the present invention is to provide an electric wire that can respond to energy saving and high efficiency of coil parts such as transformers, which are passive parts, as the frequency of equipment increases. High-frequency coil wires used as coils (reactors, inductors, choke coils, noise filters, IH heaters, power transformers, etc.) using insulated wires in the high-frequency field that uses power semiconductors, and wires made from these high-frequency coil wires It is to provide a coil.

(1) An electric wire for a high-frequency coil according to the present invention is a primary stranded wire obtained by twisting a plurality of insulated wires having a central conductor and an insulating layer provided on the outer periphery of the central conductor, and further twisting the primary stranded wire. A high-frequency coil electric wire having a collective strand structure in which at least a secondary strand is formed by
The bundled twisted wire structure is a structure in which any one selected from a secondary twisted wire, a tertiary twisted wire and a quaternary twisted wire is the outermost twisted wire, and the number of the outermost twisted wires is 3 or more and 6 or less. is within the range of

According to the present invention, the bundled strand structure is a structure in which any one selected from the secondary strand, the tertiary strand and the quaternary strand is the outermost strand, and the number of the outermost strand is three. By setting the number of wires to be within the range of 6 or less, the resistance loss effect can be further suppressed without causing current imbalance. As a result, by fabricating a coil with this electric wire for high frequency coils, it is possible to contribute to energy saving and efficiency enhancement of coil components such as transformers, which are passive components.

In the high-frequency coil wire according to the present invention, it is preferable that the pitch of the twisted wire at each stage constituting the bundled twisted wire structure is within the range of the following formula. In the formula below, Y is the twist pitch (mm) and X is the number of each twist stage (1-4) from the primary to the quaternary strands.
8.65X+22≧Y≧8.15X−3 (1)
4≧X≧1 (2)

According to the present invention, when the total outer diameter increases as the number of twisting steps is increased by setting the pitch of the twisted wires in each step constituting the bundled twisted wire structure within the range of the above calculation formula, the preferable twist pitch is An electric wire for high-frequency coils with good coil winding properties can be obtained.

In the high-frequency coil wire according to the present invention, the diameter of the central conductor is within the range of 0.04 mm or more and 0.12 mm or less, and the number of the insulating wires is within the range of 19 or more and 5000 or less.

In the high-frequency coil wire according to the present invention, it is preferable that the central conductor is a copper wire made of tough pitch copper or oxygen-free copper, or a magnetic wire in which the copper wire is provided with a magnetic layer.

In the high-frequency coil wire according to the present invention, the insulating layer is preferably an enamel coating layer or an imidazole compound layer.

In the high-frequency coil wire according to the present invention, an insulating coating layer is provided on the outer periphery of the bundled strand structure, and the insulating coating layer is composed of an insulating extruded resin, an insulating tape, or a combination thereof. is preferred.

(2) A coil according to the present invention is characterized by using the electric wire for a high frequency coil according to the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the electric wire for high frequency coils which can contribute to energy saving and efficiency improvement of coil components, such as a transformer which is a passive component, and the coil produced with the electric wire for high frequency coils are provided with the high frequency of an apparatus. be able to. In particular, high-order stranded wires such as a primary stranded wire, a secondary stranded wire obtained by further twisting the primary stranded wire, and a tertiary stranded wire obtained by further twisting the secondary stranded wire have a large total cross-sectional area. Although it is an electric wire with a large current capacity, it is preferable as an energy-saving and highly efficient coil electric wire that can cope with high frequency devices.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional schematic diagram showing an example of an electric wire for a high-frequency coil according to the present invention, where (A) is a two-stage bundled strand structure consisting of a primary strand and a secondary strand, and (B) is a primary strand. (C) is a four-stage bundled strand structure consisting of primary to quaternary strands. FIG. 2 is a configuration diagram showing an example of a primary twisted wire; It is an example of the insulated wire constituting the primary stranded wire, in which (A) is a copper wire provided with an insulating layer, and (B) is a magnetic wire provided with an insulating layer. (A) is a cross-sectional photograph of the high-frequency coil electric wire of Example 2, and (B) is a cross-sectional photograph of the electric wire of Comparative Example 1. FIG. FIG. 2 is a configuration diagram showing an example of the high-frequency coil electric wire according to the present invention, and is an example in which the insulating coating layer is configured with three layers.

A high-frequency coil wire and coil 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]
As shown in FIGS. 1 to 5, a high-frequency coil electric wire 20 according to the present invention is obtained by twisting a plurality of insulated wires 3 having a central conductor 1 and an insulating layer 2 provided on the outer periphery of the central conductor 1. The high-frequency coil electric wire comprises a bundled stranded wire structure 10 having a primary stranded wire 11 and at least a secondary stranded wire 12 by further twisting the primary stranded wire 11 . The bundled strand structure 10 has a structure in which any one selected from the secondary strand 12, the tertiary strand 13 and the quaternary strand 14 is the outermost strand, and the number of the outermost strand is three. It is characterized by being in the range of 1 or more and 6 or less.

The bundled strand structure 10 of the high-frequency coil electric wire 20 has a structure in which any one selected from the secondary strand 12, the tertiary strand 13, and the quaternary strand 14 is the outermost strand. By setting the number of wires to be in the range of 3 or more and 6 or less, it is possible to further suppress the resistance loss effect without causing current imbalance. As a result, by fabricating a coil with the electric wire 20 for high-frequency coils, it is possible to contribute to energy saving and efficiency enhancement of coil components such as transformers, which are passive components.

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

(Center conductor)
The central conductor 1 is not particularly limited as long as it is various conductors used as the central conductor of the insulated wire 3 that constitutes the so-called litz wire. can be done. A preferable central conductor 1 is a copper wire made of tough-pitch copper or oxygen-free copper, or a magnetic wire in which a magnetic layer 1b is provided on such a copper conductor 1a. Whether it is tough pitch copper or oxygen-free copper can be determined by a hydrogen embrittlement test according to JIS H-3510. Whether or not the magnetic layer 2b is provided can be measured by ICP emission spectrometry for qualitative and quantitative analysis.

As the central conductor 1, when the magnetic layer 1b is provided on the copper conductor 1a as shown in FIG. can be suppressed, so it is preferably applied. The magnetic layer 1b can be formed by electroplating or electroless plating as in Patent Document 1, and examples include iron, cobalt, nickel, or alloys thereof (including various permalloy alloys). can be done. In particular, a magnetic layer in which an iron-plated layer and a nickel-plated layer are provided in this order on the copper conductor 1a is preferably applied because the action of the nickel-plated layer enables soldering. The iron plating layer preferably has a thickness of 0.2 μm or more and 3.0 μm or less. When used in a high frequency coil or the like, the AC resistance is reduced and the high frequency characteristics are improved. Note that the iron plating layer may contain other elements (for example, nickel, cobalt, phosphorus, boron, etc.) as long as the effect of reducing the AC resistance is not impaired. The nickel plating layer is preferably applied because it does not degrade the high frequency characteristics that the iron plating layer acts on and it facilitates soldering. Although the thickness of the nickel plating layer is not particularly limited, it is preferably about 0.01 to 0.5 μm, for example. When the magnetic layer 1b is formed by electroplating or electroless plating, the plating solution composition and conditions are not particularly limited, and conventional means can be applied.

The diameter of the central conductor 1 is not particularly limited, but may be a diameter that can be preferably applied to the production of the high-frequency coil electric wire 20 according to the present invention configured with a large number of wires, for example, about 0.04 to 0.12 mm. preferably within the range.

(insulating layer)
The insulating layer 2 is provided on the central conductor 1 as shown in FIG. By providing the insulating layer 2, the high-frequency coil wire 20 is useful as a wire for various high-frequency coils and high-frequency coils (a stranded wire, an insulated wire in which the outer circumference of a group of wires is integrated with an insulating coating, etc.). Available. The insulating layer 2 is not particularly limited as long as it can ensure insulation, and various enamel coating layers can be used. Examples thereof include a solderable insulating enamel coating, a laminate coating layer of a solderable insulating enamel coating and a fusion-bonded enamel coating, an imidazole compound layer, and the like. The solderable insulating enamel coating can be formed by applying and baking a solderable enamel paint such as general-purpose polyurethane, modified polyurethane or polyesterimide. Further, the fusion enamel coating formed on the outer circumference can be formed by applying and baking a fusion enamel paint such as nylon or epoxy.

The imidazole compound layer is formed by immersing or contacting the central conductor 1 with an imidazole compound capable of forming a complex with a metal that is a component of the central conductor 1, followed by drying. Examples of imidazole compounds include imidazole and amine organic acid salts. Imidazoles are commercially available. Imidazole reacts with copper, iron, nickel, or the like forming the central conductor 1 to form a metal imidazole complex (copper imidazole complex, iron imidazole complex, nickel imidazole complex). Incidentally, the thickness of the imidazole compound layer is preferably within the range of 0.05 to 0.5 μm. By providing the imidazole compound layer with a thickness within this range, oxidation of the central conductor 1 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 enamel film, the diameter of the final high-frequency coil 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 imidazole compound layer is not as thick as an enamel film, the amount of burnt scum during soldering is very small, and there is also the advantage that problems due to burnt scum at solder joints are less likely to occur. In addition, the formation of the imidazole compound layer has the advantage that the baking process is not required and the twisting can be performed immediately after.

(Insulated wire)
As shown in FIG. 3, the insulating wire 3 is constructed by providing an insulating layer 2 on a central conductor 1. As shown in FIG. The insulated strands 3 constitute primary strands 11 to be described later, which are then further twisted to form the final bundled strand structure 10 . The insulating strands 3 constituting the final bundled strand structure 10 have a structural form selected from secondary strands 12, tertiary strands 13, and quaternary strands 14, and the number thereof is 19 or more and 5000 or less. within the range of

(aggregate strand structure)
As shown in FIGS. 1, 2 and 4, the stranded bundle structure 10 is formed by twisting a plurality of insulating wires 3 into a primary stranded wire 11, and further twisting the primary stranded wire 11 to form at least a secondary twist. The structure is represented by line 12 .

In this bundled strand structure 10, one of the secondary strands 12, the tertiary strands 13 and the quaternary strands 14 is the outermost strand. The number of outermost twisted wires is in the range of 3 or more and 6 or less. By setting the number of the outermost twisted wires within the range of 3 or more and 6 or less, it is possible to further suppress the resistance loss effect without causing current imbalance. As a result, by fabricating a coil with this electric wire for high frequency coils, it is possible to contribute to energy saving and efficiency enhancement of coil components such as transformers, which are passive components. As shown in examples and comparative examples described later, if the number is less than 3, it is difficult to arrange the cross section into a round shape, and the outer diameter of the insulating coating layer 4 to be provided in the next step fluctuates greatly. Fluctuations may cause variations in the rate of resistance change. On the other hand, if the number exceeds 6, the value of the rate of resistance change (AC resistance/DC resistance) may not be sufficiently suppressed.

In FIG. 1, (A) is a two-stage stranded bundle structure 10 consisting of primary strands 11 and secondary strands 12, and (B) is a three-stage structure composed of primary strands 11 to tertiary strands 13. (C) is a four-stage twisted bundle structure 10 consisting of primary strands 11 to quaternary strands 14 .

It is preferable that the pitch of the twisted wires in each stage constituting the bundled twisted wire structure 10 is within the range of the following formula. In the formula below, Y is the twist pitch (mm) and X is the number of each twist stage (1-4) from the primary to the quaternary strands.
8.65X+22≧Y≧8.15X−3 (1)
4≧X≧1 (2)

By setting the pitch Y of the twisted wires in each stage constituting the stranded bundle structure 10 within the range of the above calculation formula, when the total outer diameter increases with each increase in the twisting stage, the preferable twist pitch Y is set to the coil winding. The high-frequency coil electric wire 20 having good linearity can be obtained. If the pitch Y is less than the lower limit of the above range, the linear speed becomes slow, which may reduce the production efficiency and increase the cost. On the other hand, if the pitch Y exceeds the upper limit of the above range, it is difficult to maintain the shape of the stranded wire, and the twist tends to be disturbed, which may lead to variations in the resistance change rate and an increase in the AC resistance.

(insulating coating layer)
The insulating coating layer 4 is provided on the outer circumference of the bundled strand structure 10, as shown in FIGS. FIG. 5 shows an example of a three-layer insulated wire in which the insulating coating layer 4 is composed of three layers (4a, 4b, 4c). This insulating coating layer 4 is preferably made of an insulating extruded resin, an insulating tape, or a combination thereof. The insulating coating layer 4 may be a single layer, or may be a laminate as shown in FIG. Moreover, the insulating coating layer 4 may be laminated by combining tape winding and extrusion.

(Wires and coils for high frequency coils)
The high-frequency coil wire 20 thus configured is a coil (reactor, inductor, choke coil, noise filter, IH heater, power transformer) using an insulated wire for high-frequency fields that use power semiconductors such as motors, inverters, and contactless power supply. etc.). This high-frequency coil electric wire 20 can suppress an increase in resistance change rate, can exhibit stable high-frequency characteristics, and can be manufactured at a low cost as a small-diameter high-frequency coil electric wire.

As described above, the high-frequency coil electric wire 20 according to the present invention can contribute to energy saving and efficiency improvement of coil components such as transformers, which are passive components, as the frequency of devices increases. In particular, high-order stranded wires such as a primary stranded wire, a secondary stranded wire obtained by further twisting the primary stranded wire, and a tertiary stranded wire obtained by further twisting the secondary stranded wire have a large total cross-sectional area. Although it is an electric wire with a large current capacity, it is preferable as an energy-saving and highly efficient coil electric wire that can cope with high frequency devices. In particular, the present invention can be preferably applied to power semiconductor-related parts as a key device of power electronics technology that supports electrification technology for hybrid vehicles (HEV), electric vehicles (EV), and the like. With the switching frequency of such devices shifting to higher frequencies, it is preferably applied as a winding material for coils such as transformers and inductors, which are passive components used in these devices.

As a specific application, for example, DC/DC converter efficiency can be improved by the effect of being able to suppress an increase in resistance change rate. In particular, in a DC converter, the heat generation of the inductor and the efficiency of the DC/DC converter can be improved by applying it as a winding wire for the inductor.

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"
As the central conductor 1, a tough pitch copper wire with a diameter of 0.10 mm was prepared by cold drawing tough pitch copper with a diameter of 0.9 mm. Next, after the center conductor 1 was heat-treated to remove processing strain, a polyurethane film was applied and baked to form an insulating layer 2, and an insulating wire 3A having a diameter of 0.120 mm was obtained. Eighteen of these insulated wires 3A were assembled and primary stranded at a pitch of 20 mm to obtain a primary stranded wire 11 having a diameter of about 0.585 mm. Subsequently, three of the primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.01 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 54. As shown in FIG. Furthermore, PFA was melt-extruded to a thickness of 0.1 mm around the outer periphery of the secondary stranded wire 12 to produce an insulated wire 20 having an outer diameter of about 1.21 mm.

[Example 2]
In Example 1, 14 insulated wires 3A were gathered and primary twisted at a pitch of 20 mm to obtain a primary twisted wire 11 having a diameter of about 0.516 mm. Subsequently, four of these primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.03 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 56. As shown in FIG. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.23 mm was produced.

[Example 3]
In Example 1, eleven insulated wires 3A were gathered and primary twisted at a pitch of 20 mm to obtain a primary twisted wire 11 having a diameter of approximately 0.458 mm. Subsequently, five of these primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.03 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 55. As shown in FIG. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.22 mm was produced.

[Example 4]
In Example 1, nine insulated wires 3A were gathered and primary twisted at a pitch of 20 mm to obtain a primary twisted wire 11 having a diameter of approximately 0.414 mm. Subsequently, six of these primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.01 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 54. As shown in FIG. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.21 mm was produced.

[Example 5]
As the central conductor 1, a tough pitch copper conductor 1a with a diameter of 0.10 mm is prepared by cold drawing tough pitch copper with a diameter of 0.9 mm. A layer (magnetic layer 1b) and a nickel plating layer having a thickness of 0.05 μm were sequentially formed. Next, after the center conductor 1 was heat-treated to remove processing strain, a polyurethane film was applied and baked to form an insulating layer 2, thereby obtaining an insulating wire 3B having a diameter of 0.120 mm. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.21 mm was produced.

[Example 6]
An insulated wire 20 having an outer diameter of about 1.23 mm was produced in the same manner as in Example 2, except that 14 insulated wires 3B obtained in Example 5 were gathered to form a primary stranded wire 11.

[Example 7]
An insulated wire 20 having an outer diameter of about 1.22 mm was produced in the same manner as in Example 3, except that eleven insulated wires 3B obtained in Example 5 were assembled to form a primary stranded wire 11.

[Example 8]
An insulated wire 20 having an outer diameter of about 1.21 mm was produced in the same manner as in Example 4, except that nine insulated wires 3B obtained in Example 5 were gathered to form a primary stranded wire 11.

[Comparative Example 1]
In Example 1, eight insulated wires 3A were assembled and primary stranded at a pitch of 20 mm to obtain a primary stranded wire 11 having a diameter of approximately 0.390 mm. Subsequently, seven of these primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.03 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 56. As shown in FIG. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.23 mm was produced.

[Comparative Example 2]
In Example 5, eight insulated wires 3B were gathered and primary twisted at a pitch of 20 mm to obtain a primary twisted wire 11 having a diameter of about 0.390 mm. Subsequently, seven of these primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.03 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3B is 56. As shown in FIG. Otherwise, in the same manner as in Example 5, an insulated wire 20 having an outer diameter of about 1.23 mm was produced.

[Comparative Example 3]
In Example 1, 28 insulated wires 3A were gathered and primary twisted at a pitch of 20 mm to obtain a primary twisted wire 11 having a diameter of about 0.730 mm. Subsequently, two of the primary stranded wires 11 were assembled and secondary stranded at a pitch of 30 mm to obtain a secondary stranded wire 12 having a diameter of about 1.08 mm. Here, the outermost twisted wire is the secondary twisted wire 12, and the total number of the insulating wires 3A is 56. As shown in FIG. Otherwise, in the same manner as in Example 1, an insulated wire 20 having an outer diameter of about 1.23 mm was produced.

[Measurements and results]
Using the insulated wires 20 of Examples 1 to 8 and Comparative Examples 1 and 2, the rate of change in resistance was measured. DC resistance was measured with a YOKOGAWA resistance meter. A helical coil was produced from each insulated wire 20 (number of turns: 6 turns, winding frame diameter 65 mm), and was measured in the range from 100 kHz to 1000 kHz with an impedance analyzer. The resistance change rate was calculated by dividing the AC resistance at each frequency by the DC resistance. These results are shown in Tables 1 and 2.

From the results of Tables 1 and 2, as in Examples 1 to 8, the resistance change rate of the insulated wire 20 manufactured using any of the insulated wires 3A and 3B is comparable to that of Comparative Examples 1 and 2. It was found to be relatively suppressed. This tendency is more conspicuous as the frequency becomes higher (for example, 300 kHz or higher), and it was found to be more effective in the high frequency band. Specifically, at 200 kHz or more, there is a difference of about 20% between Examples 1 to 8 and Comparative Examples 1 and 2, and the number of outermost twisted wires is within the range of 3 to 6. was confirmed to be superior to the seven samples of Comparative Examples 1 and 2. From this, it can be seen that the proximity effect is dominant in the increase in AC resistance at frequencies of 200 kHz or higher. Furthermore, when the number of the outermost twisted wires (secondary twisted wires 12) is seven, one unit of twisted strands of the primary twisted wire 11 located in the center remains at the position as it is, and the outermost twisted wire (secondary twisted wire 12) stays at the position as it is. It is conceivable that current bias occurs in the child twist of 6 units. Further, when comparing Examples 1 to 4 with Examples 5 to 8, Examples 5 to 8, in which the central conductor 1 provided with a magnetic layer is applied, have a frequency of 300 kHz or higher compared to Examples 1 to 4. The difference was more pronounced, and the difference became more pronounced as the frequency increased. At 1 MHz, where the difference was most conspicuous, a difference in the effect of suppressing the resistance loss of 70% or more was obtained between the two, confirming a high effect despite the provision of the magnetic layer. In Comparative Example 3, it was difficult to arrange the cross section into a round shape, the outer diameter varied greatly after the insulating coating layer 4 was provided, and the resistance change rate varied greatly.

1 Central conductor 1a Copper conductor 1b Magnetic layer 2 Insulating layer 3 Insulating wire 3A Copper wire as central conductor 3B Conducting wire provided with magnetic layer as central conductor 4 Insulating coating layer 4a First insulating coating 4b Two Insulating coating of layer 4c Insulating coating of third layer 10 Collective strand structure 11 Primary strand 12 Secondary strand 13 Tertiary strand 14 Quaternary strand 20 High-frequency coil wire

Claims (5)

A set of 9 or more and 18 or less insulated wires having a central conductor and an insulating layer provided on the outer periphery of the central conductor to form a primary stranded wire, and the primary stranded wires are further twisted to form a secondary stranded wire. An electric wire for high-frequency coils having a stranded wire structure (excluding the case where the central portion of the cross section is a hollow portion, a core wire, a shaft member, or an insulator) ,
The central conductor has a diameter of 0.04 mm or more and 0.12 mm or less,
The number of secondary strands in the bunched strand structure is in the range of 3 or more and 6 or less ,
An electric wire for a high-frequency coil , wherein an insulating coating layer is provided on the outer circumference of the bundled strand structure, and the insulating coating layer is composed of an insulating extruded resin, an insulating tape, or a combination thereof . 2. The high-frequency coil electric wire according to claim 1, which is a three-layer insulated electric wire in which said insulating coating layer is composed of three layers. 3. The high-frequency coil wire according to claim 1 , wherein said central conductor is a copper wire made of tough-pitch copper or oxygen-free copper, or a magnetic wire in which said copper wire is provided with a magnetic layer. The high-frequency coil wire according to any one of claims 1 to 3 , wherein said insulating layer is an enamel coating layer or an imidazole compound layer. A coil using the high-frequency coil wire according to any one of claims 1 to 4 .

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