JP2015225747A - Perfect square conductor wire for coil, perfect square insulation electric wire using it, and coil using the perfect square insulation electric wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a holding performance of a coil shape, because, when flexure diameter of an electric wire is reduced for size reduction of a coil, elastic repulsion force of the electric wire is increased, so that, even when a coil shape is held by interposition of a thermoplastic resin fusion layer between electric wires, when, for example, the coil is subjected to high temperature heat treatment for high temperature sinter using reflow or magnetic powder, the fusion layer is fused and the coil shape is released due to elastic repulsion force of the electric wire.SOLUTION: Provided is a perfect square conductor wire for coil whose cross section is a square shape. The perfect square conductor wire is formed of Cu in which purity is 99.99 wt.% or more, and inevitable impurities, and 0.2% proof strength is equal to or less than 100 MPa.

Description

  The present invention relates to a true square conductor wire for a coil, a true square insulated wire, and a coil using the same.

  Inductor parts of mobile devices such as mobile phones are required to have a smaller coil and a higher space factor in order to extend the battery life. And as a coil which respond | corresponds to this request | requirement, the thing of the structure which wound the square-shaped insulated wire (henceforth "electric wire") whose cross-sectional shape is a square is mentioned.

  For example, Patent Document 1 discloses a rectangular electric wire for a coil in which an insulating layer is provided by electrodeposition coating on the outer periphery of a copper wire formed into a rectangular shape by cold working. Patent Document 2 discloses a rectangular electric wire for a coil in which the outer peripheral shape is formed into a shape in close contact with an adjacent insulated wire such as a regular hexagon.

JP 2005-209378 A JP 2009-026699 A

  If the bend diameter of the wire is reduced in order to reduce the size of the coil, the elastic repulsion force of the wire will increase, so even if the coil shape is maintained with a fusion layer of thermoplastic resin between the wires, for example, When the coil is heat-treated at a high temperature for reflow or high-temperature sintering using magnetic powder, there is a problem that the fused layer is melted and the coil shape is unwound by the elastic repulsion of the electric wire.

  The subject of this invention is improving the holding | maintenance performance of a coil shape.

  The present invention is a square conductor wire for a coil having a square cross-sectional shape, and the conductor wire is made of Cu having a purity of 99.99 wt% or more and inevitable impurities, and has a 0.2% proof stress. 100 MPa or less.

  According to the present invention, a square conductor wire is composed of Cu having a purity of 99.99 wt% or more and inevitable impurities, and has a 0.2% proof stress of 100 MPa or less, so that it is soft and therefore has a small bending diameter. Even so, a high coil-shaped holding performance can be obtained.

It is a cross-sectional view of a square conductor wire for a coil according to the embodiment. It is a cross-sectional view of the square insulated wire for coils which concerns on embodiment. It is a figure which shows the process order of the manufacturing method of the square conductor wire for coils which concerns on embodiment, and the manufacturing method of the square insulated wire for coils.

  Hereinafter, embodiments will be described in detail based on the drawings.

(Square conductor wire for coil)
FIG. 1 shows a cross-sectional view of a square conductor wire 10 for a coil according to the embodiment. FIG. 2 shows a cross-sectional view of a square insulated wire 20 in which an insulating layer is formed on the outer periphery of the coil square conductor wire. The square insulated wire 20 according to the present embodiment is for manufacturing a coil as an inductor component of a mobile device such as a mobile phone.

  The square conductor wire 10 for a coil according to the present embodiment is formed of a conductor wire having a square cross section. The “square” referred to in the present invention includes those in which corners as shown in FIG. 1 are formed in an arc shape. One side of the square conductor wire for coil is 0.01 mm to 5 mm, and in particular for manufacturing a small coil, one side is 0.05 mm to 0.8 mm.

The square conductor wire 10 for coil is formed of Cu and inevitable impurities with a purity of 99.99 wt% or more. Inevitable impurities include, for example, arsenic (As), antimony (Sb), bismuth (Bi), lead (Pb), sulfur (S), iron (Fe), and the like. The total of these inevitable impurities is less than 0.01 wt%.
A preferable square conductor wire for a coil is formed of Cu having a purity of 99.999 wt% or more and unavoidable impurities, and a more preferable rectangular conductor wire for a coil is formed of Cu having a purity of 99.9999 wt% or more and an unavoidable impurity. It is a thing.
When the purity is less than 99.99 wt% Cu and inevitable impurities, the coil shape retention performance is deteriorated.

  The 0.2% proof stress of the coiled square conductor wire 10 is 100 MPa or less, and from the viewpoint of the coil shape retention performance, it is preferably 80 MPa or less, more preferably 60 MPa or less, and preferably 40 MPa or more, more preferably Is 50 MPa or more. When the 0.2% proof stress exceeds 100 MPa, repulsive force accumulates when the coil is formed, and the coil shape cannot be maintained when the coil is heat-treated at high temperature for reflow or high-temperature sintering using magnetic powder. Here, 0.2% proof stress is measured based on the offset method of JIS Z2241 13 (proof strength).

  Further, the crystal grain size of the square conductor wire (Cu) for coil is preferably 60 μm to 250 μm, more preferably 80 μm to 180 μm, and still more preferably 100 to 160 μm. When the crystal grain size is less than 60 μm, repulsive force is accumulated when the coil is formed. For example, when the coil is heat-treated at a high temperature for reflow or high-temperature sintering using magnetic powder, the coil shape tends not to be maintained. When the crystal grain size exceeds 250 μm, unevenness tends to occur on the conductor surface when processing into a coil shape, and the adhesion between an insulating layer and a conductor wire, which will be described later, tends to decrease. Here, the crystal grain size of copper is measured based on JIS H0501.

  The volume resistivity of the conductor wire 11 is preferably 1.73 μΩ · cm or less, more preferably 1.72 μΩ · cm or less. Here, the resistivity is measured based on JIS C3216-5 section 3.

  The insulating layer 12 is made of a known insulating material. Specific examples of the insulating material include epoxy resin, polyimide resin, polyamide resin, acrylic resin, polyurethane resin, polyester resin, polyesterimide resin, and polyvinyl formal resin. As a method for forming an insulating layer on the outer periphery of a square conductor wire, a known method (dipping → baking, electrodeposition → baking, spraying → baking, etc.) may be applied, but the cross-sectional shape of the conductor wire is square. Therefore, it is preferable to form an insulating layer by electrodeposition in that a favorable insulating layer can be formed at the corner. The thickness of the insulating layer is not particularly limited, but is 3 μm to 200 μm, preferably 5 μm to 100 μm, and more preferably 7 to 50 μm.

(Manufacturing method of square conductor wire for coil and square insulated wire)
The manufacturing method of the square conductor wire 10 for coils which concerns on embodiment includes a wire drawing process, a cold working process, and an annealing process, as shown in FIG. Moreover, the manufacturing method of a square insulated wire includes a washing | cleaning process and an insulating layer formation process after the said wire drawing process, a cold working process, and an annealing process. Further, when forming the fusion layer, it is wound around the bobbin through the fusion layer formation step after the insulating layer formation step.

  Here, as for these processes, each process may be performed in a batch system, and all processes may be performed in a continuous system. Further, for example, a wire drawing process and a cold processing process are performed in a continuous system. After performing, only an annealing process may be performed by a batch type, and it may carry out combining a batch type and a continuous type like the case where the subsequent washing process and insulating layer formation process are performed by a continuous type.

<Wire drawing process>
In the wire drawing process, a rough drawn wire made of Cu and inevitable impurities having a purity of 99.99 wt% or more is reduced in diameter as a bus wire, and drawn into a round wire having a circular cross section. In general, the drawing process includes a process of passing a rough drawing wire through a drawing die. The outer diameter of the rough drawn wire is, for example, 8.0 mm, and the outer diameter of the round wire after drawing is, for example, 0.05 to 0.2 mm. Note that the wire drawing is usually performed in multiple stages. For example, first, a rough drawing wire having an outer diameter of 8.0 mm is drawn so that the outer diameter is 2.6 to 3.2 mm, and then 0.6 to The wire is drawn to 0.8 mm, and further drawn to 0.05 to 0.2 mm. Moreover, you may insert an annealing process suitably in a wire-drawing process.

<Cold working process>
In the cold working process, the round wire drawn in the drawing process is cold worked into a square conductor wire having a square cross section. For cold working, for example, a round wire is passed through a deformed die (a wire drawing die having a square hole shape, see, for example, Japanese Patent No. 4416113 and Japanese Patent No. 5289533) to obtain a conductor wire having a square cross section. Examples include wire processing. Moreover, the rolling process (for example, patent 4481664 gazette) etc. which let a round line pass in the square clearance gap formed between the rollers of a cassette roller die is mentioned. In the latter method, since there is a limit between the rollers of the cassette roller die that can be controlled, for a small coil (a square conductor wire having a small length of one side of a square in a cross section), a deformed die is used. Cold working using is suitable. Specifically, the length of one side of the square of the cross section is suitable for a length of 50 μm to 800 μm.

<Annealing process>
In the annealing process, the heat treatment is performed so that the 0.2% proof stress of the square conductor wire made of Cu and inevitable impurities with a purity of 99.99 wt% or more is 100 MPa or less.

  The annealing process is preferably carried out batchwise from the viewpoint of uniformizing the characteristics in the length direction. In that case, after the bobbin wound with the square conductor wire after the cold working process is put into a heat treatment furnace, it is predetermined. It is preferable that the temperature in the furnace is increased to a predetermined holding temperature at a temperature rising rate, and after holding a predetermined holding time at the holding temperature, the temperature in the furnace is lowered at a predetermined temperature decreasing rate. At this time, the rate of temperature rise is preferably 20 ° C./h or more, more preferably 50 ° C./h or more, and preferably 2000 ° C./h or less, more preferably 1000 ° C./h or less. The holding temperature (annealing temperature) is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and preferably 1000 ° C. or lower, more preferably 800 ° C. or lower. The holding time (annealing time) is preferably 1 second or longer, more preferably 10 seconds or longer, and preferably 100 hours or shorter, more preferably 80 hours or shorter. The temperature lowering rate is preferably 10 ° C./h or more, more preferably 20 ° C./h or more, and preferably 2000 ° C./h or less, more preferably 1000 ° C./h or less. Moreover, when performing an annealing process by a continuous type, Preferably heat treatment conditions are annealing temperature 500-900 degreeC, annealing time 1-60 seconds, More preferably, annealing temperature 600-800 degreeC and annealing time 1-10 seconds.

  The annealing step is preferably performed in an inert gas atmosphere such as nitrogen gas.

<Washing process>
In the cleaning process, the oil adhering to the surface of the true square conductor wire is cleaned and the oxide film formed on the surface is removed. This cleaning and removal can be performed, for example, by immersing and pulling up a square conductor wire in a cleaning solution and then spraying an inert gas such as nitrogen gas to scatter the cleaning solution adhering to the flat conductor 11.

  Here, examples of the cleaning liquid include water (warm water), an organic solvent, an acidic aqueous solution, and an alkaline aqueous solution. When the cleaning liquid is water, the water temperature is, for example, 10 to 60 ° C. The cleaning liquid may contain a detergent.

<Insulating layer formation process>
In the insulating layer forming step, an insulating layer is provided on the outer periphery (surface) of the true square conductor wire. Specifically, (1) The straight square conductor wire is continuously passed through a bathtub filled with an insulating material (insulating varnish), pulled up, and the insulating varnish is applied to the outer periphery of the true square conductor wire. Subsequently, the insulating varnish is baked around the conductor wire to form an insulating layer through a baking furnace. After application, before entering the baking furnace, the excess insulating varnish can be removed by passing it through a die having a square hole slightly larger than the shape of the cross section of the conductor wire, and an insulating layer of the flat portion to be formed, The thickness with the insulating layer at the corner becomes uniform. (2) By passing a square conductor wire continuously through an electrodeposition tank filled with an insulating material (electrodeposition liquid) and applying a voltage to the electrodeposition liquid using the square conductor wire as one electrode. An insulating film is deposited on the surface of the square conductor wire, and the insulating layer is formed by passing it through a baking furnace and baking the insulating film deposited on the square conductor wire.
The above (1) is preferable in that it can be faster than the above (2).
The above (2) is preferable in that a thin insulating layer having a uniform thickness of the insulating layer at the flat part and the corner part can be obtained from the above (1).

  The baking temperature, that is, the temperature inside the baking furnace is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, still more preferably 200 ° C. or higher, and preferably 600 ° C. or lower, more preferably 550 ° C. or lower. More preferably, it is 500 ° C. or lower. The baking time is preferably 300 seconds or longer, more preferably 600 seconds or longer, and preferably 1800 seconds or shorter. The baking time can be adjusted by setting the traveling speed of the square conductor wire.

  The baking process may be performed in one stage depending on a single baking process temperature, or may be performed in multiple stages at different baking process temperatures. In the latter case, for example, the baking process temperature in each stage is fixed to 100 to 600 seconds, the baking process temperature is set to 150 to 180 ° C. in the first stage, and the baking process temperature is set to be higher than that in the first stage in the second stage. A higher baking temperature is set to 180 to 210 ° C., and a third baking temperature is set to a higher baking temperature than the second temperature to 210 to 240 ° C., and finally the baking temperature is cooled to room temperature. Thus, foaming in the insulating coating layer 12 can be suppressed by sequentially setting the baking temperature higher.

<Fusion layer forming process>
Further, after the insulating layer forming step, a fusion layer forming step may be added as necessary. As the fusion layer, a thermosetting resin having heat resistance (melting point, glass transition point) after curing may be applied, and specific resins include phenol resin, epoxy resin, polyimide resin and the like. Among them, it is preferable to apply a polyimide resin from the viewpoint of easily obtaining a low-viscosity solution obtained by dissolving these resins in a solvent and having high heat resistance and high adhesive strength in a high-temperature atmosphere. The outer layer of the insulated wire is coated with a mixture of one or more of phenolic resin, epoxy resin, polyimide resin, etc., or a solution in which a part of the epoxy resin is converted to phenolic resin in a solvent. Or dipped in a bath of the solution and pulled up to coat. Thereafter, the solvent is volatilized and removed by a drying process to form a fused layer. The thickness of the fusion layer is preferably 1 to 100 μm, and preferably 5 to 30 μm. If the thickness is less than 1 μm, the insulating layers may contact each other by the external force acting in the bobbin winding process or the like, and the fusion layers may be easily damaged. If the thickness is greater than 100 μm, the solvent is removed even after the dry removal process. The fusing layer itself tends to have adhesiveness, and the possibility of blocking in the bobbin winding process or the like increases. As the solvent for dissolving the above-described resin, a known solvent may be applied, and for example, cresol, toluene, xylene, MEK, acetone, DMF, and the like can be applied.

<Bobbin winding process>
The produced square insulated wire is wound around a bobbin according to a predetermined length. A bobbin having a known shape may be applied, and it is more preferable to adopt a shape in which the bobbin is less likely to twist and fall during winding.

(coil)
The coil according to the present embodiment is not particularly limited as long as it is produced by winding a square insulated wire by a known manufacturing method. For example, it may be coiled by alpha winding, edgewise winding, or the like.
The coil shape (the shape seen from the plane) is circular or elliptical. In the case of a circle, the coil winding diameter is 500 μm to 2000 μm. According to the coil according to the present embodiment having the above configuration, since the square conductor in the coil square insulated wire is formed of Cu and inevitable impurities with a purity of 99.99 wt% or more, the conventional general same size In addition, the conductor resistance is lower than that of the same shape, and hence the resistance of the coil is also reduced, and high performance can be obtained.

  The minimum value of the bending diameter of the coiled square insulated wire constituting the coil according to the present embodiment is preferably 2.0 mm or less, more preferably 1.8 m or less, from the viewpoint of miniaturization of the coil. From the viewpoint of coil shape holding performance, it is preferably 0.5 mm or more, more preferably 1.5 mm or more. When the bending diameter is reduced, there is a problem that the coil shape is unwound due to the elastic repulsive force of the electric wire. However, according to the coil according to the present embodiment, the purity of the true square conductor wire in the square insulated wire for coil is 99.000. It is made of 99 wt% or more of Cu and unavoidable impurities, and 0.2% proof stress is 100 MPa or less, so it is relatively soft, so even a small coil with a small bending diameter has a high coil shape. Holding performance can be obtained.

  According to the coil according to the present embodiment, the square conductor wire in the coil square insulated wire is relatively soft, and therefore there is no fusion layer between adjacent coil forming portions of the coil square insulated wire. However, it is possible to obtain a high coil shape holding performance. In addition, since the fusion layer is not interposed, the size of the coil can be reduced. In addition, even when the produced coil is heat-treated at a high temperature for high-temperature sintering using reflow or magnetic powder, the coil shape is not unraveled by the elastic repulsion of the square insulated wire for coil.

Example 1: A drawn wire with a diameter of φ8.0 mm (purity: 99.9999 wt% or more consisting of Cu and inevitable impurities) is drawn to φ0.5 mm (round wire), and then the round wire is deformed by cold working A square conductor wire produced by passing through a die (drawing die having a square hole shape) to form a conductor wire having a square cross section (one side is 450 μm) was wound around a bobbin.
A bobbin around which a square conductor wire was wound was placed in a heat treatment furnace and a nitrogen atmosphere was applied, and heat treatment was performed at 350 ° C. for 5 hours.
Example 2: A bobbin around which a square conductor wire was wound was put in a heat treatment furnace, and a heat treatment was performed in a nitrogen atmosphere at a heat treatment condition of 400 ° C. for 5 hours (otherwise, the same as in the example).
Example 3 A bobbin around which a square conductor wire was wound was placed in a heat treatment furnace, and a heat treatment was performed in a nitrogen atmosphere at a heat treatment condition of 800 ° C. for 5 hours (otherwise, the same as in the example).
Comparative Example 1: A bobbin around which a square conductor wire was wound was placed in a heat treatment furnace in a nitrogen atmosphere, and heat treatment was performed at 150 ° C. for 5 hours (otherwise, the same as in the example). It was not heat-treated (otherwise it was the same as the example).

Table 1 shows the 0.2% proof stress value of the square conductor wire and the average crystal grain size as seen from the cross section.

  The straight square conductor wires of Examples 1 to 3 and Comparative Example 1 were pretreated (cleaned), an insulating layer was subsequently formed by electrodeposition, and the fusion layer was applied to the outer periphery of the insulating layer by dipping and dried, followed by bobbins Rolled up.

  In Examples 1 to 3, even if a coil wound around a circular coil having an inner diameter of 2.0 mm (10 turns) is reflow-treated, the fused layer melts and the coil shape can be solved by the elastic repulsion of the electric wire. However, in Comparative Example 1, the coil shape was unwound when the reflow process was performed.

  INDUSTRIAL APPLICABILITY The present invention is useful for a true rectangular conductor wire for a coil, a true square insulated wire using the conductor wire, and a coil using the same.

10 Square Insulated Wire for Coil 11 True Square Conductor Wire 12 Insulating Layer

Claims (4)

  A square conductor wire for a coil having a square cross section, the conductor wire comprising Cu and inevitable impurities with a purity of 99.99 wt% or more, and a 0.2% proof stress of 100 MPa or less. A true square conductor wire for a coil. In the square wire for a coil according to claim 1,
A square insulated wire for a coil, wherein an insulating layer is formed on an outer periphery of the conductor wire. In the square insulated wire for coils described in claim 2,
A square insulated wire for a coil, wherein a fusion layer is formed on the outer periphery of the insulating layer.   A coil formed by winding a square insulated wire for a coil according to claim 2 or claim 3.

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