Cu-Ag-Based Alloy WIRE

Description

TECHNICAL FIELD

The present disclosure relates to a Cu—Ag-based alloy wire.

BACKGROUND ART

A wire for electric and electronic equipment has been reduced in a single wire diameter, and instead of a pure copper wire having insufficient strength, a copper alloy wire such as a Cu—Sn-based, Cu—Cr-based, or a Cu—Ag-based wire is used.

In response to an increase in density and miniaturization of electronic devices, electric wires such as electrical/electronic device connection cables and speaker coils tend to be further reduced in diameter. Among copper alloys, Cu—Ag-based alloys are excellent in strength and electrical conductivity, and have a good balance therebetween.

For example, in a Cu—Ag-based alloy wire of Patent Document 1, a eutectic phase of Cu and Ag is elongated in a filament shape to achieve high strength and high electrical conductivity. In particular, Patent Document 1 discloses a technique of developing a recrystallization texture by heat treatment during the process and increasing strength by subsequent high processing. However, in Patent Document 1, since an appropriate wire drawing process is not performed before the heat treatment, embrittlement of the material during the heat treatment progresses, making it difficult to thin the wire, which makes it difficult to obtain a product having cost competitiveness due to poor productivity. In addition, with respect to a Cu—Ag-based alloy wire made thinner, no study has been made on the point of improving characteristics (bending fatigue resistance) such that the alloy wire is less likely to break due to fatigue under a use condition in which bending is repeated.

CITATION LIST

Patent Document

• • Patent Document 1: Japanese Patent No. 5051647

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

An object of the present disclosure is to provide a Cu—Ag-based alloy wire that has high tensile strength and high electrical conductivity and is also excellent in bending fatigue resistance.

Means for Solving the Problems

[1] A Cu—Ag-based alloy wire, including an alloy composition containing 1.00% by mass or more and 6.00% by mass or less of Ag, with a balance being Cu and inevitable impurities, having a metal structure including a Cu alloy phase as a matrix phase and a second phase precipitate containing an Ag phase, having a tensile strength of 950 MPa or more when Ag is contained in an amount of 1.00% by mass or more and less than 1.50% by mass, a tensile strength of 1050 MPa or more when Ag is contained in an amount of 1.50% by mass or more and less than 3.00% by mass, a tensile strength of 1200 MPa or more when Ag is contained in an amount of 3.00% by mass or more and less than 5.00% by mass, and a tensile strength of 1450 MPa or more when Ag is contained in an amount of 5.00% by mass or more and 6.00% by mass or less, and when a linear distance from the surface to the center in a transverse section of the Cu—Ag-based alloy wire is defined as L, an average concentration of Ag in a surface annular region having a length of L/100 from the surface toward the center is defined as c1, and an average concentration of Ag in a central region having a length of 99L/100 from the center toward the surface is defined as c2, a value (c1-c2) obtained by subtracting c2 from c1 being 1.00% by mass or more and 3.00% by mass or less.

[2] The Cu—Ag-based alloy wire as described in [1], in which, in a binarized image in which a STEM dark field image of the transverse section is converted to gray scale and a low luminance side and a high luminance side are binarized to white and black, respectively, a ratio (n1/n2) of an average number density n1 (pieces/μm²) of black portions in the surface annular region to an average number density n2 (pieces/μm²) of black portions in the central region is 2.0 or more and 6.0 or less.

[3] The Cu—Ag-based alloy wire as described in [1] or [2], in which the alloy composition further contains 0.05% by mass or more and 0.30% by mass or less in total of one or more elements selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr.

[4] The Cu—Ag-based alloy wire as described in any one of [1] to [3], in which the Cu—Ag-based alloy wire is a round wire having a diameter of 0.01 mm or more and 0.08 mm or less.

[5] The Cu—Ag-based alloy wire as described in any one of [1] to [3], in which the Cu—Ag-based alloy wire is a ribbon wire having a width of 0.020 mm or more and 0.320 mm or less and a thickness of 0.002 mm or more and 0.040 mm or less.

Effects of the Invention

According to the present disclosure, it is possible to provide a Cu—Ag-based alloy wire that has high tensile strength and high electrical conductivity and is also excellent in the bending fatigue resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a surface annular region and a central region in a transverse section of a Cu—Ag-based alloy wire (round wire) of an embodiment.

FIG. 2 is a schematic view illustrating a surface annular region and a central region in a transverse section of a Cu—Ag-based alloy wire (ribbon wire) of an embodiment.

FIG. 3 is a diagram illustrating that the number of black portions was counted in a binarized image obtained from a STEM dark field image of the Cu—Ag-based alloy wire of Example 1.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the embodiments will be described in detail.

As a result of intensive studies, the present inventors have found that, by having a predetermined alloy composition, by controlling a relationship between an average concentration c1 of Ag in a surface annular region and an average concentration c2 of Ag in a central region of a transverse section to a predetermined range, and by controlling a tensile strength in a predetermined alloy compositional range to a predetermined range, the Cu—Ag-based alloy wire has high tensile strength and high electrical conductivity, as well as excellent bending fatigue resistance, having completed the present disclosure based on such finding.

The Cu—Ag-based alloy wire according to an embodiment includes an alloy composition containing 1.00% by mass or more and 6.00% by mass or less of Ag, with a balance being Cu and inevitable impurities, having a metal structure including a Cu alloy phase as a matrix phase and a second phase precipitate containing an Ag phase, having a tensile strength of 950 MPa or more when Ag is contained in an amount of 1.00% by mass or more and less than 1.50% by mass, a tensile strength of 1050 MPa or more when Ag is contained in an amount of 1.50% by mass or more and less than 3.00% by mass, a tensile strength of 1200 MPa or more when Ag is contained in an amount of 3.00% by mass or more and less than 5.00% by mass, and a tensile strength of 1450 MPa or more when Ag is contained in an amount of 5.00% by mass or more and 6.00% by mass or less, and when a linear distance from the surface to the center in a transverse section of the Cu—Ag-based alloy wire is defined as L, an average concentration of Ag in a surface annular region having a length of L/100 from the surface toward the center is defined as c1, and an average concentration of Ag in a central region having a length of 99L/100 from the center toward the surface is defined as c2, a value (c1-c2) obtained by subtracting c2 from c1 being 1.00% by mass or more and 3.00% by mass or less.

First, the alloy composition of the Cu—Ag-based alloy wire will be described.

The Cu—Ag-based alloy wire of the above embodiment has an alloy composition including 1.00% by mass or more and 6.00% by mass or less of Ag, with a balance being Cu and inevitable impurities.

<Ag: 1.00% by Mass or More and 6.00% by Mass or Less>

Silver (Ag) is an element necessary for increasing tensile strength of the Cu—Ag-based alloy wire, and the Cu—Ag-based alloy wire contains 1.00% by mass or more and 6.00% by mass or less of Ag. When a content of Ag is 1.00% by mass or more, the tensile strength of the Cu—Ag-based alloy wire can be increased due to solid solution or precipitation of Ag. When the content of Ag is 6.00% by mass or less, a decrease in the electrical conductivity of the Cu—Ag-based alloy wire can be suppressed, and a high electrical conductivity of the Cu—Ag-based alloy wire can be ensured. Further, when the content of Ag is more than 6.00% by mass, it is difficult for the content of Ag to contribute to a value-added product of a customer because an increase in the strength cannot be expected to an extent which meets an increase in a material cost due to an increase in an amount of Ag used. In order to balance between improvement in the tensile strength and improvement of the electrical conductivity of the Cu—Ag-based alloy wire, the Ag content is 1.00% by mass or more, preferably 1.50% by mass or more, and on the other hand, 6.00% by mass or less, and preferably 4.00% by mass or less.

<Sub-Component of Cu—Ag-Based Alloy Wire: 0.05% by Mass or More and 0.30% by Mass or Less>

The alloy composition of the Cu—Ag-based alloy wire may further contain 0.05% by mass or more and 0.30% by mass or less in total amount of one or more elements selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr. That is, the Cu—Ag-based alloy wire may further contain, in addition to Ag as an essential basic component, at least one component selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr in a total amount of 0.05% by mass or more and 0.30% by mass or less as an optional component being sub-component. When a content of the sub-component is 0.05% by mass or more, tensile strength of the Cu—Ag-based alloy wire is improved, and some of the elements achieve an effect of alleviating brittleness of the Cu—Ag-based alloy wire. When the content of the sub-component is 0.30% by mass or less, the electrical conductivity of the Cu—Ag-based alloy wire is not significantly impaired. Therefore, the content of the sub-component is preferably 0.05% by mass or more, more preferably 0.08% by mass or more, and even more preferably 0.10% by mass or more, and on the other hand, the content is preferably 0.30% by mass or less, more preferably 0.25% by mass or less, and even more preferably 0.20% by mass or less.

<Sn: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of tin (Sn) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and the content of Sn of 0.20% by mass or less does not significantly impair the electrical conductivity of the Cu—Ag-based alloy wire. Therefore, the content of Sn is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the Sn content is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Mg: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of magnesium (Mg) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and achieves an effect of alleviating brittleness of the Cu—Ag-based alloy wire. When the content of Mg is 0.20% by mass or less, the electrical conductivity of the Cu—Ag-based alloy wire and the manufacturability during casting are not significantly impaired. Therefore, the content of Mg is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Mg is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Zn: 0.05% by Mass or More and 0.30% by Mass or Less>

A content of zinc (Zn) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and achieves an effect of alleviating brittleness of the Cu—Ag-based alloy wire. When the content of Zn is 0.30% by mass or less, the electrical conductivity of the Cu—Ag-based alloy wire is not significantly impaired. Therefore, the content of Zn is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Zn is preferably 0.30% by mass or less, more preferably 0.25% by mass or less, even more preferably 0.20% by mass or less, and particularly preferably 0.15% by mass or less.

<In: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of indium (In) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and the content of In of 0.20% by mass or less does not significantly impair the electrical conductivity of the Cu—Ag-based alloy wire. Therefore, the content of In is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of In is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Ni: 0.05% by Mass or More and 0.30% by Mass or Less>

A content of nickel (Ni) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire. When the content of Ni is 0.30% by mass or less, the electrical conductivity of the Cu—Ag-based alloy wire is not significantly impaired. Therefore, the content of Ni is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Ni is preferably 0.30% by mass or less, more preferably 0.25% by mass or less, even more preferably 0.20% by mass or less, and particularly preferably 0.15% by mass or less.

<Co: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of cobalt (Co) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and the content of Co of 0.20% by mass or less does not significantly impair the electrical conductivity of the Cu—Ag-based alloy wire. Therefore, the content of Co is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Co is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Zr: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of zirconium (Zr) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire and achieves an effect of alleviating brittleness of the Cu—Ag-based alloy wire. When the content of Zr is 0.20% by mass or less, the electrical conductivity of the Cu—Ag-based alloy wire and the manufacturability during casting are not significantly impaired. Therefore, the content of Zr is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Zr is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Cr: 0.05% by Mass or More and 0.20% by Mass or Less>

A content of chromium (Cr) of 0.05% by mass or more contributes to improvement in the tensile strength of the Cu—Ag-based alloy wire, and the content of Cr of 0.20% by mass or less does not significantly impair the electrical conductivity of the Cu—Ag-based alloy wire. Therefore, the content of Cr is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, even more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, and on the other hand, the content of Cr is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less.

<Balance: Cu and Inevitable Impurities>

The balance other than the above-described components is copper (Cu) and inevitable impurities. The inevitable impurities are unavoidably added during the manufacturing process, and depending on a content thereof, also can be a factor of lowering one or more characteristics of tensile strength, electrical conductivity, or bending fatigue resistance of the Cu—Ag-based alloy wire, and affects the environment and causes material embrittlement. Therefore, a content of the inevitable impurities is preferably as small as possible. Examples of the inevitable impurities include elements such as S, Pb, Sb, and Bi. The upper limit of the content of the inevitable impurities is preferably less than 0.0001% by mass for each element, and is preferably less than 0.0005% by mass in total of the elements.

The Cu—Ag-based alloy wire is a copper alloy wire and has a metal structure including a Cu alloy phase as a matrix phase and a second phase precipitate containing an Ag phase. The second phase precipitate is precipitated into the Cu alloy phase which is the matrix phase, and is composed of the Ag phase (Ag single phase) or the like.

FIG. 1 is a schematic view illustrating the surface annular region and the central region in a transverse section of a Cu—Ag-based alloy wire (round wire) according to an embodiment. FIG. 2 is a schematic view illustrating the surface annular region and the central region in a transverse section of a Cu—Ag-based alloy wire (ribbon wire) according to an embodiment. As shown in FIGS. 1 and 2, in the transverse section of the Cu—Ag-based alloy wire 1, which is a cross-section perpendicular to the longitudinal direction of the Cu—Ag-based alloy wire 1, when a linear distance from a surface 1a of the Cu—Ag-based alloy wire 1 to a center 1b of the Cu—Ag-based alloy wire 1 is defined as L, a region from the surface 1a toward the center 1b with a length L/100 is defined as a surface annular region R1, and a region from the center 1b toward the surface 1a with a length 99 L/100 is defined as a central region R2. A value (c1-c2) obtained by subtracting an average concentration c2 of Ag in the central region R2 from an average concentration c1 of Ag in the surface annular region R1 is 1.00% by mass or more and 3.00% by mass or less.

When the transverse section of the Cu—Ag-based alloy wire 1 is a perfect circle, the linear distance L from the surface 1a to the center 1b is constant, the surface annular region R1 is annular, and the central region R2 is a perfect circle. When the transverse section of the Cu—Ag-based alloy wire 1 is not a perfect circle, the linear distance L from the surface 1a to the center 1b is not constant. For example, when the transverse section of the Cu—Ag-based alloy wire 1 is rectangular as shown in FIG. 2, the linear distance L is not constant, the surface annular region R1 is a rectangular annular region, and the central region R2 is a rectangular region.

When the value (c1-c2) is within the above range, the tensile strength and the bending fatigue resistance of the Cu—Ag-based alloy wire can be improved. In particular, when the Cu—Ag-based alloy wire is bent, a stronger stress is applied to the surface of the Cu—Ag-based alloy wire than to the center portion of the Cu—Ag-based alloy wire. Therefore, when the value (c1-c2) is 1.00% by mass or more, an amount of Ag solid solution in the surface annular region R1 increases, whereby the tensile strength of the Cu—Ag-based alloy wire can be improved, as well as the strength of surface of the Cu—Ag-based alloy wire increases to improve the bending fatigue resistance. Further, when the value (c1-c2) is 3.00% by mass or less, a decrease in the tensile strength of the Cu—Ag-based alloy wire due to an insufficient amount of Ag solid solution in the central region R2 can be suppressed, whereby it is possible to suppress disconnection of the Cu—Ag-based alloy wire.

When the alloy composition contains Ag in an amount of 1.00% by mass or more and less than 1.50% by mass, the tensile strength of the Cu—Ag-based alloy wire is 950 MPa or more, and preferably 1050 MPa or more. When the alloy composition contains Ag in an amount of 1.50% by mass or more and less than 3.00% by mass, the tensile strength of the Cu—Ag-based alloy wire is 1050 MPa or more, and preferably 1150 MPa or more. When the alloy composition contains Ag in an amount of 3.00% by mass or more and less than 5.00% by mass, the tensile strength of the Cu—Ag-based alloy wire is 1200 MPa or more, and preferably 1300 MPa or more. When the alloy composition contains Ag in an amount of 5.00% by mass or more and 6.00% by mass or less, the tensile strength of the Cu—Ag-based alloy wire is 1450 MPa or more, and preferably 1550 MPa or more.

When the tensile strength of the Cu—Ag-based alloy wire is within the above range, even if the Cu—Ag-based alloy wire is an ultrafine wire having a smaller wire diameter than conventional wire diameters, the tensile strength, the electrical conductivity, and the bending fatigue resistance can be balanced at a high level.

In addition, in a binarized image in which a STEM dark field image of the transverse section of the Cu—Ag-based alloy wire 1 shown in FIGS. 1-2 is converted to gray scale and a low luminance side and a high luminance side are respectively binarized to white and black, a ratio (n1/n2) of an average number density n1 (number/μm²) of black portions in the surface annular region R1 to an average number density n2 (number/μm²) of black portions in the central region R2 is preferably 2.0 or more and 6.0 or less.

Formation of the black portion in the binarized image as a high-density fiber-like precipitate at the time of wire drawing in the method for producing the Cu—Ag-based alloy wire (hereinafter, also simply referred to as black portion) can further improve the tensile strength. When the ratio (n1/n2) is within the above range, the tensile strength and the bending fatigue resistance of the Cu—Ag-based alloy wire can be further improved. In particular, since a stronger stress is applied to the surface of the Cu—Ag-based alloy wire than to the central portion of the Cu—Ag-based alloy wire at the time of bending of the Cu—Ag-based alloy wire, when the ratio (n1/n2) is 2.0 or more, by an increase in the black portion of the surface annular region R1, the tensile strength of the Cu—Ag-based alloy wire can be further improved, and the strength of the surface of the Cu—Ag-based alloy wire increases to further improve the bending fatigue resistance. When the ratio (n1/n2) is 6.0 or less, it is possible to suppress a decrease in the tensile strength of the Cu—Ag-based alloy wire due to the lack of the black portion in the central region R2.

The Cu—Ag-based alloy wire is preferably a round wire having a diameter of 0.01 mm or more and 0.08 mm or less. In this case, the transverse section of the Cu—Ag-based alloy wire has a circular shape having a diameter of 0.01 mm or more and 0.08 mm or less. Even when the Cu—Ag-based alloy wire is a round wire having a wire diameter within the above range, in other words, even when the Cu—Ag-based alloy wire is an extremely thin round wire, the Cu—Ag-based alloy wire has high tensile strength and high electrical conductivity and is also excellent in bending fatigue resistance.

The Cu—Ag-based alloy wire may be a ribbon wire having a width of 0.020 mm or more and 0.320 mm or less and a thickness of 0.002 mm or more and 0.040 mm or less. In this case, the transverse section of the Cu—Ag-based alloy wire has a ribbon shape (rectangular shape) having a long side of 0.020 mm or more and 0.320 mm or less and a short side of 0.002 mm or more and 0.040 mm or less. Even when the Cu—Ag-based alloy wire is a ribbon wire having a size within the above range, that is, the Cu—Ag-based alloy wire is an extremely thin ribbon wire, the Cu—Ag-based alloy wire has high tensile strength and high electrical conductivity and is also excellent in bending fatigue resistance.

The tensile strength, the electrical conductivity, and the bending fatigue resistance of the Cu—Ag-based alloy wire, which is a ribbon wire, are not significantly different from the tensile strength, the electrical conductivity, and the bending fatigue resistance of the Cu—Ag-based alloy wire, which is a round wire before being formed into the ribbon shape. That is, if the tensile strength, the electrical conductivity, and the bending fatigue resistance of the Cu—Ag-based alloy wire before being formed into a ribbon shape are equal to or greater than predetermined values, the tensile strength, the electrical conductivity, and the bending fatigue resistance of the Cu—Ag-based alloy wire, which is a ribbon wire, are equal to or greater than predetermined values.

As described above, the Cu—Ag-based alloy wire is excellent in bending fatigue resistance while having high tensile strength and high electrical conductivity, and thus is suitably used for a connection cable for electric and electronic devices. As a result, it becomes easy to reduce the size of the electric/electronic apparatus, to save the space of the electric wire installation area, and to increase the number of signal wiring lines, which have not been easily realized so far, and it is possible to contribute to a higher added value with respect to the reduction in size of the electric/electronic product.

Next, a method of manufacturing the Cu—Ag-based alloy wire will be described.

In the method for producing the Cu—Ag-based alloy wire, first, a casting step is performed in which a raw material is melted so as to have a predetermined alloy composition and then casting and rolling are performed to obtain a rough drawn wire. The cooling rate during casting and solidification in the casting step is 10° C./s or more and 100° C./s or less. When the cooling rate is more than 100° C./s, an unsolidified molten metal does not effectively flow into the gap in the previously solidified surface layer portion, and therefore, the value (c1-c2) of the finally obtained Cu—Ag-based alloy wire becomes less than 1.00% by mass, and in addition, the ratio (n1/n2) becomes less than 2.00% by mass even when the heat treatment step to be described later is performed. On the other hand, when the cooling rate is less than 10° C./s, the value (c1-c2) of the Cu—Ag-based alloy wire is more than 3.00% by mass, which is not preferable from the viewpoint of productivity and quality maintenance.

After the casting step, a first wire drawing step of performing cold wire drawing at a processing ratio of 50% or more and 90% or less is performed. When the processing ratio is less than 50%, crystal precipitation of a sufficient amount of fine black portions does not occur in the heat treatment step to be described later. Further, when the processing ratio is less than 50%, there is also a problem that void defects grow. On the other hand, when the processing ratio is more than 90%, it is difficult to perform wire drawing at a high processing ratio in a second wire drawing step to be described later. Therefore, the first wire drawing step is performed at a processing ratio of 50% or more and 90% or less from the viewpoint of promoting crystal precipitation of a sufficient amount of fine black portions, suppressing void growth, and sufficiently securing room for wire drawing in the second wire drawing step being the subsequent step.

Here, the processing ratio is a value obtained by dividing a value obtained by subtracting the transverse section area of the sample after the wire drawing from the transverse section area of the sample before the wire drawing by the transverse section area of the sample before the wire drawing, multiplying the divided value by 100 to express the result as a percentage, and is represented by the following formula.

[ processing ⁢ ratio ] = { ( [ transverse ⁢ section ⁢ area ⁢ of ⁢ sample ⁢ before ⁢ wire ⁢ drawing ] -  [ transverse ⁢ section ⁢ area ⁢ of ⁢ sample ⁢ after ⁢ wire ⁢ drawing ] ) /  [ transverse ⁢ section ⁢ area ⁢ of ⁢ sample ⁢ before ⁢ wire ⁢ drawing ] } × 100 ⁢ ( % ) .

The first wire drawing step can be performed by a known method such as drawing using a die. The first wire drawing step may be performed in one pass, or may be performed in a plurality of passes until a target wire diameter is obtained.

After the first wire drawing step, a heat treatment step which is generally called aging heat treatment is performed for the purpose of crystal precipitation of the black portion. The heat treatment is performed at a retention temperature of 300° C. or higher and 400° C. or lower for a retention time of 10 seconds or more and 30 minutes or less, and preferably 5 minutes or more and 30 minutes or less. When the retention temperature is lower than 300° C. or the retention time is less than 10 seconds, the black portion is not sufficiently generated. On the other hand, when the retention temperature exceeds 400° C., diffusion is promoted and the value (c1-c2) becomes less than 1.00% by mass. In addition, precipitation and diffusion of the solute also progresses due to an increase in the retention time of the heat treatment step. When the retention time is 10 seconds or more and 5 minutes or less, precipitation significantly proceeds in the surface layer of the wire, and the ratio (n1/n2) becomes 2.0 or more. When the retention time is 5 minutes or more and 30 minutes or less, the ratio (n1/n2) is 2.0 or more, and precipitation becomes active in the entire wire, so that the tensile strength increases. When the retention time exceeds 30 minutes, diffusion proceeds, and thus the value (c1-c2) becomes less than 1.00% by mass.

The heat treatment step can be performed by using a known method, such as a batch type heat treatment or a continuous heat treatment such as high frequency heating, energization heating, or running heating.

When the heat treatment or the aging heat treatment is performed at a temperature higher than the above-described retention temperature, a solution heat treatment (generally at 700 to 900° C. for about 10 minutes to 5 hours) generally performed thereafter is not preferable because it is difficult to obtain the metal structure satisfying the requirements of the Cu—Ag-based alloy wire of the embodiment. In addition, such a treatment is not preferable because there is a possibility of release of segregation or promotion of void defect growth.

Following the heat treatment step, a second wire drawing step is performed in which wire cold drawing is performed at a processing ratio of 99.700% or more and 99.998% or less after cooling. When the processing ratio is less than 99.700%, the tensile strength does not sufficiently increase. On the other hand, it is difficult to set the processing ratio to more than 99.998% in terms of processing technology. Therefore, the second wire drawing step is performed at a processing ratio of 99.700% or more and 99.998% or less.

The second wire drawing step can be performed by a known method such as drawing using a die. The second wire drawing step may be performed in one pass, or may be performed in a plurality of passes until a target wire diameter is obtained. Thus, a Cu—Ag-based alloy wire, which is a round wire, can be produced.

In addition, although the above-described manufacturing method is mainly a method for manufacturing a round wire, a Cu—Ag-based alloy wire, which is a ribbon wire, can be manufactured by rolling the round wire manufactured by the above-described manufacturing method to a specified thickness.

According to the embodiment described above, by having the predetermined alloy composition, by controlling the relationship between the average concentration c1 of Ag in the surface annular region and the average concentration c2 of Ag in the central region of the transverse section to the predetermined range, and by controlling the tensile strength in the predetermined alloy compositional range to the predetermined range, it is possible to obtain the Cu—Ag-based alloy wire having excellent bending fatigue resistance, while having high tensile strength and high electrical conductivity.

Although the embodiments have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present disclosure, including all aspects included in the concept of the present disclosure and the claims.

EXAMPLES

Next, Examples and Comparative Examples will be described, but the present disclosure is not limited to these Examples.

Examples 1-1 to 1-11, 2-1 to 2-11, 3-1 to 3-11, 4-1 to 4-11 and 5-1 to 5-8 and Comparative Examples 1-1 to 1-6, 2-1 to 2-6, 3-1 to 3-6, 4-1 to 4-6 and 5-1

In order to obtain the alloy compositions shown in Tables 1 to 5, the raw materials were melted in the air, cast, and rolled to obtain rough drawn wires having a wire diameter of 6 to 39 mm. In the casting step, the cooling rate during casting and solidification was controlled to values shown in Tables 1 to 5. Next, each of these rough drawn wires was cold drawn at the processing ratio shown in Tables 1 to 5 to have a wire diameter of 4 to 9 mm. Next, the heat treatment was performed at the retention temperature and the retention time shown in Tables 1 to 5. Note that in Comparative Examples 1-2, 2-2, 3-2, 4-2 and 5-1, heat treatment was not performed. After cooling, the cold drawing was performed at the processing ratio shown in Tables 1 to 5 to obtain the Cu—Ag-based alloy wires, which are round wires having the wire diameters shown in Tables 6 to 10.

Example 1-12, 2-12, 3-12 and 4-12

In order to obtain the alloy compositions shown in Tables 1 to 4, the raw materials were melted in the air, cast, and rolled to obtain rough drawn wires having a wire diameter of 6 to 39 mm. In the casting step, the cooling rate during casting and solidification was controlled to values shown in Tables 1 to 4. Next, each of these rough drawn wires was cold drawn at the processing ratio shown in Tables 1 to 4 to have a wire diameter of 4 to 9 mm. Next, the heat treatment was performed at the retention temperature and the retention time shown in Tables 1 to 4. After cooling, the cold drawing was performed at the processing ratio shown in Tables 1 to 4 to obtain the Cu—Ag-based alloy wires, which are round wires. Next, the Cu—Ag-based alloy wires, which are round wires, were rolled to obtain the Cu—Ag-based alloy wires, which are ribbon wires having the thicknesses and the widths shown in Tables 6 to 9.

In the Tables below, the data on which the Comparative Examples are based are underlined and italicized.

TABLE 1
Cu-1.00% by mass Ag

Production conditions

Casting step

	Cooling rate	First wire		Second wire
	during casting	drawing step	Heat treatment step	drawing step

	and	Processing	Retention	Retention	Processing
	solidification	ratio	temperature	time	ratio
	(° C./s)	(%)	(° C.)	(s)	(%)

Example 1-1	60	60	350	200	99.990
Example 1-2	100	60	350	200	99.990
Example 1-3	10	60	300	200	99.990
Example 1-4	60	90	350	200	99.990
Example 1-5	60	50	350	200	99.990
Example 1-6	60	60	400	200	99.990
Example 1-7	60	60	300	200	99.990
Example 1-8	60	60	350	1800	99.990
Example 1-9	60	60	350	10	99.990
Example 1-10	60	60	350	200	99.700
Example 1-11	60	60	350	200	99.998
Example 1-12	60	60	350	200	99.990
Comparative	550	60	350	200	99.990
Example 1-1
Comparative	60	60	—	—	99.998
Example 1-2
Comparative	60	60	200	200	95.000
Example 1-3
Comparative	80	60	500	200	99.998
Example 1-4
Comparative	80	60	350	6000	99.998
Example 1-5
Comparative	3	60	350	200	99.998
Example 1-6

TABLE 2
Cu-2.00% by mass Ag

Production conditions

Casting step

	Cooling rate	First wire		Second wire
	during casting	drawing step	Heat treatment step	drawing step

	and	Processing	Retention	Retention	Processing
	solidification	ratio	temperature	time	ratio
	(° C./s)	(%)	(° C.)	(s)	(%)

Example 2-1	60	60	350	200	99.990
Example 2-2	100	60	350	200	99.990
Example 2-3	10	60	300	200	99.990
Example 2-4	60	90	350	200	99.990
Example 2-5	60	50	350	200	99.990
Example 2-6	60	60	400	200	99.990
Example 2-7	60	60	300	200	99.990
Example 2-8	60	60	350	1800	99.990
Example 2-9	60	60	350	10	99.990
Example 2-10	60	60	350	200	99.700
Example 2-11	60	60	350	200	99.998
Example 2-12	60	60	350	200	99.990
Comparative	550	60	350	200	99.990
Example 2-1
Comparative	60	60	—	—	99.998
Example 2-2
Comparative	60	60	200	200	95.000
Example 2-3
Comparative	80	60	500	200	99.998
Example 2-4
Comparative	80	60	350	6000	99.998
Example 2-5
Comparative	3	60	350	200	99.998
Example 2-6

TABLE 3
Cu-4.00% by mass Ag

Production conditions

Casting step

	Cooling rate	First wire		Second wire
	during casting	drawing step	Heat treatment step	drawing step

	and	Processing	Retention	Retention	Processing
	solidification	ratio	temperature	time	ratio
	(° C./s)	(%)	(° C.)	(s)	(%)

Example 3-1	60	60	350	200	99.990
Example 3-2	100	60	350	200	99.990
Example 3-3	10	60	300	200	99.990
Example 3-4	60	90	350	200	99.990
Example 3-5	60	50	350	200	99.990
Example 3-6	60	60	400	200	99.990
Example 3-7	60	60	300	200	99.990
Example 3-8	60	60	350	1800	99.990
Example 3-9	60	60	350	10	99.990
Example 3-10	60	60	350	200	99.700
Example 3-11	60	60	350	200	99.998
Example 3-12	60	60	350	200	99.990
Comparative	550	60	350	200	99.990
Example 3-1
Comparative	60	60	—	—	99.998
Example 3-2
Comparative	60	60	200	200	95.000
Example 3-3
Comparative	80	60	500	200	99.998
Example 3-4
Comparative	80	60	350	6000	99.998
Example 3-5
Comparative	3	60	350	200	99.998
Example 3-6

TABLE 4
Cu-6.00% by mass Ag

Production conditions

Casting step

	Cooling rate	First wire		Second wire
	during casting	drawing step	Heat treatment step	drawing step

	and	Processing	Retention	Retention	Processing
	solidification	ratio	temperature	time	ratio
	(° C./s)	(%)	(° C.)	(s)	(%)

Example 4-1	60	60	350	200	99.990
Example 4-2	100	60	350	200	99.990
Example 4-3	10	60	300	200	99.990
Example 4-4	60	90	350	200	99.990
Example 4-5	60	50	350	200	99.990
Example 4-6	60	60	400	200	99.990
Example 4-7	60	60	300	200	99.990
Example 4-8	60	60	350	1800	99.990
Example 4-9	60	60	350	10	99.990
Example 4-10	60	60	350	200	99.700
Example 4-11	60	60	350	200	99.998
Example 4-12	60	60	350	200	99.990
Comparative	550	60	350	200	99.990
Example 4-1
Comparative	60	60	—	—	99.998
Example 4-2
Comparative	60	60	200	200	95.000
Example 4-3
Comparative	80	60	500	200	99.998
Example 4-4
Comparative	80	60	350	6000	99.998
Example 4-5
Comparative	3	60	350	200	99.998
Example 4-6

TABLE 5
Cu-2.00% by mass Ag

Production conditions

Casting step

First wire

Second wire

Sub-component

Cooling rate

drawing step

Heat treatment step

drawing step

		Content	during casting	Processing	Retention	Retention	Processing
		(% by	and solidification	ratio	temperature	time	ratio
	Element	mass)	(° C./s)	(%)	(° C.)	(h)	(%)

Example 5-1	Sn	0.10	60	60	350	200	99.990
Example 5-2	Mg	0.10	60	60	350	200	99.990
Example 5-3	Zn	0.30	60	60	350	200	99.990
Example 5-4	In	0.10	60	60	350	200	99.990
Example 5-5	Ni	0.20	60	60	350	200	99.990
Example 5-6	Co	0.10	60	60	350	200	99.990
Example 5-7	Zr	0.05	60	60	350	200	99.990
Example 5-8	Cr	0.10	60	60	350	200	99.990
Comparative	Sn	0.10	60	60	—	—	99.990
Example 5-1

[Evaluation]

The Cu—Ag-based alloy wires obtained in the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Tables 6 to 10.

[1] Tensile Strength

Using the Cu—Ag-based alloy wires (two wires, n=2) obtained in the above Examples and Comparative Examples, a tensile test was performed in accordance with JIS Z 2241:2011, and the tensile strength was calculated by averaging the two measured values.

[2] Bending Fatigue Resistance

Using the Cu—Ag-based alloy wires obtained in the above Examples and Comparative Examples, a repeated bending test was carried out in accordance with JIS H 0500 No. 4100. Specifically, since the fatigue property is dependent on the wire diameter, the wire diameters of the Cu—Ag-based alloy wires to be used in the repeated bending test were unified to 0.03 mm in the following manner: for the Cu—Ag-based alloy wire having a wire diameter of less than 0.03 mm, the Cu—Ag-based alloy wire having a wire diameter of more than 0.03 mm, and the Cu—Ag-based alloy wire of a ribbon wire, the wire diameters of the Cu—Ag-based alloy wires were equalized to 0.03 mm by using of wires in the middle of processing.

The Cu—Ag-based alloy round wire with a wire diameter of 0.03 mm was used as a test target, a radius R of a jig at a bending fulcrum during bending of the Cu—Ag-based alloy wire was set to 6 mm, one end of the Cu—Ag-based alloy wire was fixed by a clamp, a weight of 30 g was suspended to the other end of the Cu—Ag-based alloy wire so as not to bend the Cu—Ag-based alloy wire, the number of times until the Cu—Ag-based alloy wire reached a break was counted, and an average value (average bending life, n=5) thereof was evaluated on the basis of whether or not the relationship of the following formulas 1 to 3 was satisfied.

In a case where the numerical value of the average bending life satisfies the following formula 1, the Cu—Ag-based alloy wire is rated as being “superb” in the bending fatigue resistance, in a case where the numerical value of the average bending life does not satisfy the following formula 1 but satisfies the following formula 2, the Cu—Ag-based alloy wire is rated as being “excellent” in the bending fatigue resistance, in a case where the numerical value of the average bending life does not satisfy the following formulas 1 to 2, but satisfies the following formula 3, the Cu—Ag-based alloy wire is rated as being “good” in the bending fatigue resistance, and in a case where none of the following formulas 1 to 3 is satisfied, the Cu—Ag-based alloy wire is rated as being “poor” in the bending fatigue resistance.

average ⁢ bending ⁢ life ≧ 5900 × ( Ag ⁢ concentration ⁢ of ⁢ alloy ⁢ composition ) + 40000 Formula ⁢ 1 average ⁢ bending ⁢ life ≧ 5900 × ( Ag ⁢ concentration ⁢ of ⁢ alloy ⁢ composition ) + 20000 Formula ⁢ 2 average ⁢ bending ⁢ life ≧ 5900 × ( Ag ⁢ concentration ⁢ of ⁢ alloy ⁢ composition ) + 5000 Formula ⁢ 3

[3] Electrical Conductivity

The Cu—Ag-based alloy wires (n=2) obtained in the above Examples and Comparative Examples were measured in accordance with JIS H0505: 1975, and the electrical conductivity was calculated by averaging two measured values.

[4] Average Ag Concentration

The transverse section perpendicular to the longitudinal direction of each Cu—Ag-based alloy wire obtained in the above Examples and Comparative Examples was subjected to a thinning treatment processing by a focused ion beam (FIB) method. For the processing, SIINT-3050 TB (manufactured by SII Nano Technology) was used, and the acceleration voltage of Ga ion beam was set to 30 kV. After the processing, Ar ion milling was performed on the sample surface at an acceleration voltage of 2 kV for 5 minutes in order to remove damage of the sample. Thus, a sample for observation was obtained.

Using an atomic resolution analytical electron microscope (ARM: JEM-ARM200F manufactured by JEOL) having an aberration correction function, the surface annular region and the central region on the surface of the observation sample were observed with an acceleration voltage of an electron beam set to 200 kV and an observation region set to a square having one side of 130 nm, and a high-angle annular dark field scanning STEM (HAADF-STEM) image (STEM dark field image) of the surface annular region and the central region was obtained. The surface annular region and the central region, which are observation regions, were randomly selected at three positions on the surface of the observation sample. Then, each of the STEM dark field images was subjected to energy dispersive X-ray spectroscopy (EDX) analysis attached to STEM to measure the concentration of Ag in the surface annular region and the concentration of Ag in the central region, and the average concentration c1 of Ag in the surface annular region and the average concentration c2 of Ag in the central region were calculated by averaging three measured values.

[5] Average Number Density of Black Portions

Using the image processing software “Image J (version v1. 53 k)”, each STEM dark field image obtained above was subjected to the following processing to calculate an average number density of the black portions. First, an arbitrary range of 400 nm² to 800 nm² was trimmed from each STEM dark field image, and the trimmed image was converted to gray scale. Next, in the histogram of the luminance value of the gray-scaled image, a low luminance side and a high luminance side were binarized to white and black, respectively, with upper 0.5 to 2.0% as a threshold. Further, after removing black portions of 1 pixel or less as noise, a region having a continuous contour of the remaining black portion was defined as one black portion, and the number of black portions was counted. The number density of black portions was calculated by dividing the counted number of black portions by an area of the trimming image. The average number density n1 of the black portions in the surface annular region and the average number density n2 of the black portions in the central region were obtained by averaging three measured values.

TABLE 6
Cu-1.00% by mass Ag

Cu—Ag-based alloy wire

	Ag average			Average
	concen-	Ag average		number	Average
	tration	concen-		density	number
	c1 in	tration		n1 in	density

surface

c2 in

c1 −

surface

n2 in

Evaluation

		Wire	annular	central	c2	annular	central		Tensile	Bending	Electrical
		diameter	region	region	(% by	region	region	n1/	strength	fatigue	conductivity
	Shape	(mm)	(% by mass)	(% by mass)	mass)	(pieces/μm2)	(pieces/μm2)	n2	(MPa)	resistance	(% IACS)

Example 1-1	Round wire	0.03	2.38	1.01	1.37	880	220	4.0	1050	Superb	79
Example 1-2	Round wire	0.03	2.10	1.08	1.02	700	240	2.9	1070	Excellent	77
Example 1-3	Round wire	0.03	2.72	0.79	1.93	1010	170	5.9	1030	Superb	82
Example 1-4	Round wire	0.03	2.12	1.00	1.12	710	210	3.4	1060	Superb	81
Example 1-5	Round wire	0.03	2.18	0.90	1.28	630	170	3.7	1020	Superb	80
Example 1-6	Round wire	0.03	1.89	0.85	1.04	670	190	3.5	1070	Superb	78
Example 1-7	Round wire	0.03	2.38	0.66	1.73	670	140	4.8	1060	Superb	82
Example 1-8	Round wire	0.03	2.07	0.66	1.41	680	150	4.5	1090	Excellent	76
Example 1-9	Round wire	0.03	2.99	1.18	1.80	420	65	6.5	960	Good	83
Example 1-10	Round wire	0.01	2.25	0.70	1.55	34590	7060	4.9	1100	Superb	82
Example 1-11	Round wire	0.08	2.50	0.80	1.70	550	110	5.0	1040	Excellent	80
Example 1-12	Ribbon	Thickness:	2.20	1.10	1.10	780	240	3.3	1060	Superb	81
	wire	0.008
		Width:
		0.080
Comparative	Round wire	0.03	1.43	1.13	0.30	300	240	1.2	1040	Poor	76
Example 1-1
Comparative	Round wire	0.03	2.01	0.81	1.20	110	30	3.8	910	Poor	91
Example 1-2
Comparative	Round wire	0.03	2.56	0.86	1.70	160	34	4.8	930	Poor	88
Example 1-3
Comparative	Round wire	0.03	1.60	0.90	0.70	310	180	1.7	1020	Poor	84
Example 1-4
Comparative	Round wire	0.03	1.60	1.30	0.30	340	280	1.2	1050	Poor	82
Example 1-5
Comparative	Round wire	0.03	3.50	0.40	3.10	1190	120	9.9	940	Poor	87
Example 1-6

TABLE 7
Cu-2.00% by mass Ag

Cu—Ag-based alloy wire

	Ag average			Average
	concen-	Ag average		number	Average
	tration	concen-		density n1	number
	c1 in	tration		in surface	density n2

surface

c2 in

c1 −

annular

in central

Evaluation

		Wire	annular	central	c2	region	region		Tensile	Bending	Electrical
		diameter	region (%	region (%	(% by	(pieces/	(pieces/	n1/	strength	fatigue	conductivity
	Shape	(mm)	by mass)	by mass)	mass)	μm2)	μm2)	n2	(MPa)	resistance	(% IACS)

Example 2-1	Round wire	0.03	3.45	1.75	1.70	2970	570	5.2	1180	Superb	76
Example 2-2	Round wire	0.03	3.20	2.00	1.20	2070	680	3.0	1190	Excellent	73
Example 2-3	Round wire	0.03	3.37	1.37	2.00	2330	410	5.7	1160	Superb	81
Example 2-4	Round wire	0.03	3.40	1.90	1.50	2510	630	4.0	1170	Superb	75
Example 2-5	Round wire	0.03	3.20	1.70	1.50	2360	540	4.4	1160	Superb	79
Example 2-6	Round wire	0.03	3.20	2.10	1.10	1960	700	2.8	1150	Excellent	81
Example 2-7	Round wire	0.03	3.60	1.70	1.90	2850	520	5.5	1160	Superb	79
Example 2-8	Round wire	0.03	3.70	1.90	1.80	3090	630	4.9	1190	Superb	73
Example 2-9	Round wire	0.03	3.80	1.70	2.10	810	120	6.8	1070	Good	78
Example 2-10	Round wire	0.01	3.60	2.30	1.30	20470	5320	3.8	1200	Superb	74
Example 2-11	Round wire	0.08	3.30	1.80	1.50	330	80	4.1	1140	Excellent	81
Example 2-12	Ribbon wire	Thickness:	3.60	1.70	1.50	2390	550	4.4	1170	Superb	77
		0.008
		Width:
		0.080
Comparative	Round wire	0.03	2.40	1.90	0.50	1090	640	1.7	1150	Poor	74
Example 2-1
Comparative	Round wire	0.03	3.20	1.80	1.40	260	67	3.9	990	Poor	83
Example 2-2
Comparative	Round wire	0.03	2.80	1.70	1.10	170	61	2.7	1010	Poor	83
Example 2-3
Comparative	Round wire	0.03	3.30	2.40	0.90	1460	810	1.8	1140	Poor	77
Example 2-4
Comparative	Round wire	0.03	2.70	2.10	0.60	1410	700	2.0	1170	Poor	78
Example 2-5
Comparative	Round wire	0.03	4.50	1.30	3.20	3400	330	10.3	1030	Poor	82
Example 2-6

TABLE 8
Cu-4.00% by mass Ag

Cu—Ag-based alloy wire

	Ag average			Average	Average
	concen-	Ag average		number	number
	tration	concen-		density n1	density
	c1 in	tration		in surface	n2 in

surface

c2 in

c1 −

annular

central

Evaluation

		Wire	annular	central	c2	region	region		Tensile	Bending	Electrical
		diameter	region (%	region (%	(% by	(pieces/	(pieces/	n1/	strength	fatigue	conductivity
	Shape	(mm)	by mass)	by mass)	mass)	μm2)	μm2)	n2	(MPa)	resistance	(% IACS)

Example 3-1	Round wire	0.03	6.40	3.60	2.80	4790	1050	4.7	1380	Superb	67
Example 3-2	Round wire	0.03	6.10	4.28	1.82	4800	1330	3.4	1400	Excellent	61
Example 3-3	Round wire	0.03	6.20	3.30	2.90	5930	1070	5.8	1370	Superb	69
Example 3-4	Round wire	0.03	6.40	3.89	2.51	5310	1270	4.4	1420	Superb	65
Example 3-5	Round wire	0.03	6.60	4.39	2.21	5790	1420	4.0	1360	Superb	68
Example 3-6	Round wire	0.03	6.50	4.80	1.70	4410	1690	2.6	1390	Excellent	64
Example 3-7	Round wire	0.03	7.20	4.88	2.32	7210	1750	4.1	1350	Superb	69
Example 3-8	Round wire	0.03	6.40	4.94	1.46	5110	1870	2.8	1390	Superb	64
Example 3-9	Round wire	0.03	7.20	4.40	2.80	1310	210	6.2	1230	Good	68
Example 3-10	Round wire	0.01	7.00	4.79	2.21	46780	12460	3.8	1410	Superb	62
Example 3-11	Round wire	0.08	6.10	3.48	2.62	900	190	4.7	1360	Excellent	70
Example 3-12	Ribbon wire	Thickness:	6.20	3.60	2.62	4360	1010	4.3	1360	Superb	65
		0.008
		Width:
		0.080
Comparative	Round wire	0.03	4.10	3.33	0.77	1410	870	1.6	1350	Poor	67
Example 3-1
Comparative	Round wire	0.03	6.80	3.96	2.80	800	140	5.6	1160	Poor	75
Example 3-2
Comparative	Round wire	0.03	5.90	3.57	2.33	460	120	3.8	1190	Poor	78
Example 3-3
Comparative	Round wire	0.03	5.38	4.58	0.80	1750	1580	1.1	1320	Poor	72
Example 3-4
Comparative	Round wire	0.03	4.50	4.81	−0.31	350	1730	0.2	1330	Poor	71
Example 3-5
Comparative	Round wire	0.03	7.50	3.30	4.20	8200	1310	6.3	1170	Poor	76
Example 3-6

TABLE 9
Cu-6.00% by mass Ag

Cu—Ag-based alloy wire

	Ag average			Average
	concen-	Ag average		number	Average
	tration	concen-		density n1	number
	c1 in	tration		in surface	density n2

surface

c2 in

c1 −

annular

in central

Evaluation

		Wire	annular	central	c2	region	region		Tensile	Bending	Electrical
		diameter	region (%	region (%	(% by	(pieces/	(pieces/	n1/	strength	fatigue	conductivity
	Shape	(mm)	by mass)	by mass)	mass)	μm2)	μm2)	n2	(MPa)	resistance	(% IACS)

Example 4-1	Round wire	0.03	9.10	6.20	2.90	9420	2230	4.2	1610	Superb	58
Example 4-2	Round wire	0.03	8.70	6.61	2.09	8850	2600	3.4	1630	Excellent	54
Example 4-3	Round wire	0.03	9.20	6.32	2.88	11830	2360	5.0	1610	Superb	61
Example 4-4	Round wire	0.03	8.10	5.70	2.40	8580	2860	3.0	1640	Superb	57
Example 4-5	Round wire	0.03	8.60	6.00	2.60	10960	2270	4.8	1580	Superb	56
Example 4-6	Round wire	0.03	8.30	5.60	2.70	6920	1610	4.3	1600	Excellent	52
Example 4-7	Round wire	0.03	8.80	6.10	2.70	10700	2210	4.8	1570	Superb	57
Example 4-8	Round wire	0.03	8.20	5.28	2.92	6020	1630	3.7	1640	Superb	55
Example 4-9	Round wire	0.03	8.90	6.20	2.70	2180	350	6.2	1480	Good	54
Example 4-10	Round wire	0.01	7.90	5.67	2.23	86630	19610	4.4	1650	Superb	53
Example 4-11	Round wire	0.08	8.50	6.10	2.40	10300	2180	4.7	1550	Excellent	59
Example 4-12	Ribbon wire	Thickness:	8.90	6.00	2.90	11420	2140	5.3	1630	Superb	56
		0.008
		Width:
		0.080
Comparative	Round wire	0.03	6.20	5.65	0.55	570	1900	0.3	1580	Poor	58
Example 4-1
Comparative	Round wire	0.03	7.90	5.26	2.60	900	190	4.8	1380	Poor	67
Example 4-2
Comparative	Round wire	0.03	9.10	6.50	2.60	940	230	4.1	1440	Poor	65
Example 4-3
Comparative	Round wire	0.03	6.58	5.78	0.80	1370	1960	0.7	1600	Poor	57
Example 4-4
Comparative	Round wire	0.03	6.70	6.46	0.20	770	2480	0.3	1610	Poor	55
Example 4-5
Comparative	Round wire	0.03	9.50	5.90	3.60	14020	1900	7.4	1420	Poor	63
Example 4-6

TABLE 10
Cu-2.00% by mass Ag (sub-component included)

Cu—Ag-based alloy wire

	Ag average			Average
	concen-	Ag average		number	Average
	tration	concen-		density n1	number
	c1 in	tration		in surface	density n2

surface

c2 in

c1 −

annular

in central

Evaluation

		Wire	annular	central	c2	region	region		Tensile	Bending	Electrical
		diameter	region (%	region (%	(% by	(pieces/	(pieces/	n1/	strength	fatigue	conductivity
	Shape	(mm)	by mass)	by mass)	mass)	μm2)	μm2)	n2	(MPa)	resistance	(% IACS)

Example 5-1	Round wire	0.03	3.55	2.23	1.32	2620	620	4.2	1230	Superb	77
Example 5-2	Round wire	0.03	3.68	1.46	2.23	2960	510	5.8	1180	Superb	77
Example 5-3	Round wire	0.03	3.48	1.40	2.08	2540	450	5.6	1200	Superb	76
Example 5-4	Round wire	0.03	3.73	2.56	1.17	2860	730	3.9	1220	Superb	76
Example 5-5	Round wire	0.03	3.41	2.03	1.38	2730	670	4.1	1230	Superb	74
Example 5-6	Round wire	0.03	3.60	2.47	1.13	2390	630	3.8	1200	Superb	76
Example 5-7	Round wire	0.03	3.40	1.08	2.32	2310	460	5.0	1190	Superb	78
Example 5-8	Round wire	0.03	3.61	1.32	2.29	2850	510	5.6	1240	Superb	75
Comparative	Round wire	0.03	3.64	2.35	1.29	310	80	3.9	1080	Poor	82
Example 5-1

FIG. 3 shows a STEM dark field image of the Cu—Ag-based alloy wire obtained in Example 1. As shown in Tables 1 to 10 and FIG. 3, in the Cu—Ag-based alloy wire of the above-described Example, the alloy composition was within a predetermined range, the relationship between the average concentration c1 of Ag in the surface annular region and the average concentration c2 of Ag in the central region was within a predetermined range, and the tensile strength in the predetermined alloy compositional range was within a predetermined range, so that both the tensile strength and the electrical conductivity were high and the bending fatigue resistance was excellent. On the other hand, in the Cu—Ag-based alloy wire of the Comparative Example, at least one of the alloy composition, the relationship between the average concentration c1 of Ag and the average concentration c2 of Ag, or the tensile strength in the predetermined alloy compositional range was outside the predetermined range, and therefore, at least one of the tensile strength, the electrical conductivity, or the bending fatigue resistance was poor.

EXPLANATION OF REFERENCE NUMERALS

• • 1 Cu—Ag-based alloy wire
  • 1a Surface of Cu—Ag-based alloy wire
  • 1b Center of Cu—Ag based alloy wire
  • L Distance from surface of Cu—Ag-based alloy wire to center of Cu—Ag-based alloy wire
  • R1 Surface annular region
  • R2 Central region