JP5001455B1 - Bonding wire and manufacturing method thereof - Google Patents

Abstract

Provided is a bonding wire obtained by coating Pd on pure copper having stable bonding strength that meets the demand for reduction in size between integrated circuits.
A bonding wire W having a wire diameter L of 50.8 μm or less for connecting an integrated circuit element electrode a and a circuit wiring board conductor wiring c by a ball bonding method. The core material 1 is made of pure copper and unavoidable impurities, and a coating layer 2 having a thickness t _{2 of} 0.010 to 0.090 μm is formed on the entire outer periphery of the core material 1, and 0.0001 to 0.0. A carbon enriched layer 3 having a thickness of 0005 μm t ₃ is formed. Furthermore, the furnace temperature of the refining heat treatment: 400 ° C. or higher 800 ° C. or less, the processing time is performed in 0.33 to 1 seconds, tensile by tensile test at a tensile strength TS _R and 250 ° C. by a tensile test at room temperature the ratio of the strength TS _H a _{(HR = TS H / TS R} × 100) 50 to 70%. The carbon enriched layer 3 is formed by the degree of cleaning of the lubricant during wire drawing.
[Selection] Figure 1

Description

  The present invention relates to a bonding wire for connecting an electrode on an integrated circuit element such as an IC, LSI, transistor or the like to a conductor wiring of a circuit wiring board such as a lead frame, a ceramic substrate, or a printed circuit board by a ball bonding method, and its manufacture. It is about the method.

  The connection method by this kind of ball bonding method is generally the embodiment shown in FIGS. 3A to 3H, and the wire W shown in FIG. 3A is inserted into the capillary 10a and a ball is formed at the tip thereof. From the state where (FAB: Free Air Ball) b is formed, the clamp 10b is opened, and the capillary 10a is lowered toward the electrode a on the integrated circuit element. At this time, the ball (FAB) b is captured in the capillary 10a and bonded to the electrode a.

When the ball b comes into contact with the target electrode a (when the capillary 10a reaches the electrode a), the capillary 10a grips the ball b and applies heat / load / ultrasonic wave to the ball b, whereby the ball b is pressed. (It becomes a press-bonded ball b ′) and the electrode a are solid-phase bonded, and a 1st bond is formed and adhered to the electrode a ((b) in the figure).
If the 1st bond is formed, the capillary 10a moves up to a certain height (FIG. (C)) and then moves to a position directly above the conductor wiring c (FIGs. (D) to (e)). At this time, in order to form a stable loop, there is a case where a special movement is performed on the capillary 10a so that the wire W is attached with a “string” (see the solid line from the chain line in FIG. 4D).

  The capillary 10a that has reached directly above the conductor wiring c descends toward the conductor wiring c and presses the wire W against the conductor wiring (2nd target) c (FIGS. (E) to (f)). At the same time, heat, a load, and an ultrasonic wave are applied to the pressed portion, thereby deforming the wire W and joining the wire W onto the conductor wiring c, and a tail that secures the tail in the next step. A bond is formed (figure (f)).

  After forming both the bonds, the capillary 10a rises with the wire W remaining, and after securing a tail of a certain length at the tip of the capillary 10a, the clamp 10b is closed (by grabbing the wire W), and the tail The wire W is torn off from the bond portion ((g) in the figure).

  The capillary 10a stops when it rises to the required height, and a high voltage is applied to the tip of the wire W secured at the tip of the capillary 10a with the discharge rod g to discharge (discharge) the spark. The wire W is melted, and the melted wire material becomes a spherical ball b by the surface tension and is hardened ((h) in the figure).

  One cycle is completed by the above operation, and thereafter, the electrode a and the wiring conductor c are connected by the ball bonding method by the same operation.

In the connection by this ball bonding method, a gold wire is mainly used as the bonding wire W. However, since gold is expensive, in recent years, an inexpensive copper wire having a copper purity of 99.99% by mass or more has been used. Has been done. At that time, since the oxidation of the surface is likely to occur when the copper is bare, as shown in FIG. 4, a core wire 1 made of a copper wire is coated with an oxidation resistant metal 2 is used.
As the coating metal (coating layer) 2, gold (Au), platinum (Pt), palladium (Pd), silver (Ag), nickel (Ni) or the like is employed (Patent Documents 1 to 5).

JP 2003-133361 A JP 2004-64033 A JP 2007-12776 A Japanese Patent No. 4542203 Japanese Patent No. 4349641

  In the bonding wire W made of a metal-coated copper wire, the ball b needs to be made smaller with the miniaturization of integrated circuit elements due to the recent miniaturization of electronic components. For this purpose, the diameter L is preferably 50 μm or less (paragraph 0009 in Patent Document 1).

In addition, when the ball b is in a downward bowl shape (reverse conical shape) in connection to the electrode a of the integrated circuit element, the electrode b is pressed by the sharp end of the ball b when the ball b is pressed against the electrode a. The ball b is preferably a true sphere as much as possible. To increase the sphericity of the ball b, the coating layer 2 of a thickness t ₂ core (core 1) or 0.001 or less diameter (Patent Document 1 claims 1), also the thickness of the coating layer 2 t ₂ may be 0.001 to 0.2 μm (Patent Document 3 claim 1), and the thickness t ₂ of the coating layer ₂ may be 0.021 to 0.12 μm (Patent Document 4 claim 1). The coating layer 2 is formed of an oxidation resistant metal having a melting point higher than that of copper 1 (Patent Document 2, paragraph 0014). It has also been proposed to increase the sphericity by further providing an Au skin layer around Pd or Pt of the coating layer 2. (Patent Document 5, paragraph 0011)

  Further, in the case of BGA (Ball Grid Array) based on an organic substrate, if the heating temperature (stage temperature) is increased, the warping of the organic substrate occurs and the bonding property is remarkably deteriorated. For this reason, various devices for ensuring sufficient bonding strength even when the heating temperature (stage temperature) at the time of bonding between the wire W and the electrode a or the conductor wiring c is low, for example, about 150 ° C., for example, In addition, the wire is drawn after the heat treatment (Patent Document 3, paragraphs 0020, 0054, etc.).

As described above, the bonding wire W in which the copper wire is coated with the oxidation-resistant metal has hitherto been well received by various devices. However, in recent years, in order to reduce the cost, it is required to increase the work speed, and it is necessary to further improve the bonding strength.
Further, as electronic components are miniaturized, the electrodes a stacked in multiple stages are used in order to reduce the height of the loop (lower the loop height (h in FIG. 5)) or to wire in a limited space. It is necessary to bond it. In the case of the multi-layer lamination, the first layer bonding needs to make the loop as low as possible, and the second and subsequent layers will bond beyond the bonding wires (connection lines) W of the first and subsequent layers. Conventionally, a high loop (loop height h) is required. When the loop is raised, the “Wacking” shown by the chain line in FIG. 3D is normally performed, and a wire W that can be flexibly performed is required.

  This invention makes it a subject to respond to the said request | requirement in such an actual condition.

In order to achieve the above object, the present invention provides a bonding wire W having a diameter L of 50.8 μm or less for connecting the electrode a of the integrated circuit element and the conductor wiring c of the circuit wiring board by a ball bonding method. The core material 1 is made of copper having a purity of 99.99% by mass or more and unavoidable impurities, and the coating layer 2 having a thickness t _{2 of} Pd: 0.010 to 0.090 μm is formed on the entire outer periphery of the core material 1. The ratio of the tensile strength (TS _R ) by the tensile test at room temperature and the tensile strength (TS _H ) by the tensile test at 250 ° C. (HR = TS _H / TS _R × 100) is 50 to It was set to 70%.

The reason why the diameter L of the bonding wire W is set to 50.8 μm or less is that the diameter L is set to 50 μm or less in the above-mentioned Patent Document 1, but if it is 50.8 μm or less, it is not changed to 50 μm or less. This is because the ball b can be made smaller (see Example 4).
The lower limit of the wire diameter L is not particularly defined, but if it is less than 12 μm, it becomes difficult for the operator to pass the wire W through the capillary 10a before bonding, and workability is deteriorated.
The reason why the copper purity of the core material 1 is 99.99% by mass or more (the balance is inevitable impurities) is to ensure high conductivity.

As the thickness t ₂ of the coating layer 2 is thin, the hardness of the ball b is low, Si chip is likelihood of damage (electrode a) is lowered, too thin, copper core 1 during stitch bond joining The degree of exposure becomes greater, and only the stitch bondability of a copper wire without the coating layer 2 can be exhibited. For example, as can be understood from the experimental results of Examples and Comparative Examples described later, there is a possibility that two or more machine stops may occur. For this reason, thickness t2 of the coating layer ₂ shall be 0.010 micrometer or more from the experimental result of the Example and a comparative example.

In addition, at the time of ball bonding at a stage temperature as low as about 150 ° C., the thickness t _{2 is set} to 0.040 μm or more from the experimental results of the continuous bonding property. When the stage temperature is lowered, the load required for the stitch bond bonding increases, and the degree of exposure of the copper of the core material 1 increases in the range where the thickness t ₂ of the coating layer ₂ is 0.010 μm or more and less than 0.040 μm. This is because bonding properties may be impaired.
On the other hand, if the coating layer 2 is thick, the hardness of the ball b is increased, and the possibility of failure due to damage to the Si chip (electrode a) is increased. For this reason, the thickness t2 of the coating layer ₂ shall be 0.090 micrometer or less from the experimental result of the below-mentioned Example and a comparative example.

  The reason why the coating metal is Pd is that these noble metals are generally used as coating materials for electronic materials and are relatively easy to obtain. In addition, since Pd has a melting point of 1554 ° C., which is higher than the melting point of copper (1083 ° C.), Pd does not melt first during discharge with the discharge rod g for producing the ball b, and copper melts due to surface tension. The wire is rolled up right above, and a good spherical ball b can be obtained. As for the purity of Pd, the higher the purity, the lower the hardness of the ball b. Therefore, it is preferable that the purity is 99.99% by mass or more (the remainder is an inevitable impurity) like the pure copper of the core material 1.

Various methods can be used for manufacturing the bonding wire W having these configurations. For example, the coating layer 2 made of Pd is formed on the entire outer surface of the core 1 made of copper having a purity of 99.99% by mass or more. The coated wire is subjected to diffusion heat treatment to improve the adhesion between the core material and the coating layer, and then drawn to a wire diameter of 50.8 μm or less, and further subjected to a tempering heat treatment to obtain a thickness t ₂ : 0 of the coating layer 2. A configuration of 0.010 to 0.090 μm can be adopted.

The coating layer 2 is formed by known means such as electrolytic plating, electroless plating, vapor deposition, and the like. In general, the wire W is predetermined by sequentially passing a copper rod having a large wire diameter through a tool called a die. Therefore, the coating layer 2 is formed by the above means with an appropriate wire diameter in the middle of this process. At this time, the wire diameter of the core material 1 at the time of coating is determined by workability and cost, but is generally 0.2 to 0.8 mm due to the limitation of the manufacturing apparatus. The coated wire coated with Pd on the entire outer surface is subjected to diffusion heat treatment at 200 to 500 ° C. to improve the adhesion between the core material 1 and the coating layer 2, and then drawn to a wire diameter of 50.8 μm or less. The thickness t ₂ of the coating layer 2 can be set to 0.010 to 0.090 μm. Thereafter, the wire W is subjected to a tempering heat treatment.

The tempering heat treatment is a continuous heat treatment by drawing the wire W to a predetermined wire diameter and winding the wire W around the reel, running it in a tubular heat treatment furnace, and winding it again with a take-up reel. . In the tubular heat treatment furnace, nitrogen gas or a gas obtained by mixing a small amount of hydrogen with nitrogen is allowed to flow.
In this refining heat treatment, from the comparison of Comparative Example with Examples below, the wire W of the tensile strength at room temperature according to a tensile test at is (20~25 ℃) TS _R and tensile tensile by test strength TS _H at 250 ° C. The ratio HR (TS _H / TS _R × 100) is adjusted to be 50 to 70%.

Usually, HR is governed by refining heat treatment time and treatment temperature, to less than 50%, it is necessary to increase the tensile strength TS _R at room temperature, performing refining heat treatment at a low temperature or short time. In this case, since the temperature is low and the time is short, the copper crystal structure of the wire W becomes a fine structure in which processing strain remains. On the other hand, when the ball b is formed on the wire W by the discharge of the discharge rod g in FIG. 3 (h), the wire W having a length from the ball b toward the capillary 10a is melted and recrystallized. A coarse heat-affected zone (see e in FIG. 5) of the tissue is generated. For this reason, a boundary of the crystal structure is formed at a required distance from the ball b. If the boundary of this crystal structure is in the middle of the loop, it may cause cracks in the part or breakage in some cases, so the wire can be bonded in a high loop shape (loop height). Disappear.
Further, in order HR is to exceed 70%, because it is necessary to lower the tensile strength TS _R at room temperature, performing refining heat treatment at a high temperature or long time. In this case, because of the high temperature and long time, the copper crystal structure of the wire W becomes coarse and brittle, and cracks are generated or broken from the crystal grain boundaries at the crease (curvature) part during bonding. Cause malfunction.

From the above, if the HR of the wire W according to the present invention is set to 50 to 70%, the boundary between the microstructure and the coarsened recrystallized structure does not occur from the comparison of the examples and comparative examples described later. It is considered that no cracks are generated and that the crystal structure of the wire W is not coarsened, so that no cracks are generated from the crystal grain boundaries during the soldering. For this reason, the wire W can be flexed without being cracked.
The HR: 50 to 70% can be obtained by appropriately setting the tempering heat treatment time and the treatment temperature by experiments or the like. For example, when the furnace length is 50 cm, the furnace temperature is set to 400 ° C. or more and 800 ° C. or less, and the heat treatment is performed at a wire traveling speed of 30 to 90 m / min. At this time, the tempering heat treatment time is 0.33 to 1 second.

The completed wire W is subdivided into a predetermined spool and wound up, and this spool is attached to a bonding apparatus and used for bonding by feeding out the wire W. However, due to the surface state of the coating layer 2, the wires W are in close contact with each other, You may not be able to pay out. Although Patent Document 4 describes that this feeding property is improved by providing an oxide layer on the surface of the coating layer 2, it is actually difficult to control the oxide layer on the Pd surface.
In order to prevent adhesion of the wire W, it is preferable to provide a carbon enriched layer on the surface of the coating layer 2. The carbon concentration of this carbon enrichment layer shall be 1-80 mass%. If the carbon concentration is less than 1% by mass, the effect of preventing adhesion cannot be exhibited, and if it exceeds 80% by mass, the stitch bondability may be lowered and the continuous bonding property may be impaired.

There are various methods for forming the carbon enriched layer, such as immersing the wire in a metal adhesion preventive agent or spraying a metal adhesion preventive agent on the wire, but after adjusting the concentration of the wire drawing lubricant, In order to leave a part of the lubricant on the surface of the wire W, after the cleaning for the purpose of removing excess wire drawing lubricant and foreign matters, the part of the lubricant remaining by performing a tempering heat treatment is performed. It is economical to provide a carbon enriched layer comprising: At this time, if the heat treatment is performed in the air, the drawn lubricant left on the wire W reacts with the oxygen and scatters, so the oxygen is blocked in nitrogen gas or hydrogen-nitrogen mixed gas. It shall be done in
From the experimental results of Examples and Comparative Examples described later, the thickness of the carbon enriched layer is set to 0.0001 to 0.0005 μm. If the thickness of the carbon-enriched layer is less than 0.0001 μm, the above-described pay-out property cannot be improved, and if it exceeds 0.0005 μm, the stitch bond bondability may be lowered and the continuous bondability may be impaired. .

  Since the present invention is configured as described above, it is possible to obtain a bonding wire in which pure copper having stable bonding strength is coated with Pd.

Sectional drawing of the bonding wire which concerns on this invention HR: Photomicrograph of the crystal structure of the bonding wire surface of 50 to 70% HR: Micrograph of bonding wire surface crystallographic structure less than 50% HR: Micrograph of bonding wire surface crystallographic structure exceeding 70% It is explanatory drawing of a ball bonding connection method, (a)-(h) is the middle figure Cross section of another bonding wire Enlarged view of bonding connection between electrode a and conductor wiring c

A copper wire having a purity of 99.99% by mass or more and a diameter of 0.2 to 0.8 mm is prepared. The copper wire is coated with Pd by an electrolytic plating method, and the coated wire is subjected to diffusion heat treatment to obtain a copper wire (core material). ) After improving the adhesion between 1 and the coating layer 2, the wire was drawn to a wire diameter of 12 to 50.8 μm with a water-soluble wire drawing lubricant interposed therebetween, and the tensile strength ratio HR was 45 to 78%. Thus, a tempering heat treatment was performed in nitrogen gas to obtain a bonding wire W having a thickness t ₂ of the coating layer 2 of 0.002 to 0.12 μm. At this time, the length of the furnace is adjusted after adjusting the concentration of the lubricant at the time of wire drawing and removing extra lubricant or foreign matter so that a part of the lubricant remains on the surface of the wire W in the cleaning after the wire drawing. : The above-mentioned tempering heat treatment is performed by heat treatment at an oxygen shut-off state of 50 cm, furnace temperature: 400 ° C. to 800 ° C., wire traveling speed: 30 to 90 m / min, and thickness t ₃ : carbon concentration of 0.0009 μm or less Layer 3 was provided.

  By this method, the bonding wires W of Examples 1 to 16 and Comparative Examples 1 to 9 shown in Table 1 are manufactured, and the continuous bonding property of the bonding wires W and the damage degree of the Si chip (electrode a) at the first joint portion are manufactured. The wire drawability and loop shape (presence of cracks) were evaluated by the following methods. The evaluation results are shown in Table 1.

“Thickness t _{2 of} coating layer (film layer) ₂ ”
Using a fluorescent X-ray film thickness meter, the intensity of fluorescent X-rays generated by irradiating X-rays was converted to the film thickness to obtain the film thickness.

“Thickness t ₃ of carbon enriched layer ₃ ”
Sputtering is performed in the depth direction with Ar ions for a unit time, and the carbon concentration is measured each time. The thickness t ₃ of the carbon enriched layer 3 is reached up to the point where the carbon concentration of the outermost layer is ½. Measured by Auger spectroscopy (AES). For the conversion of thickness, general SiO ₂ conversion was used.

"Tensile strength TS _H in tensile strength _TS R, 250 ° C. at room temperature"
At room temperature (23 ° C.), a tensile test was performed on a 100 mm wire at a tensile speed of 10 mm / min, and the value obtained by dividing the load at the time of fracture by the cross-sectional area of the wire W before the tensile test was taken as the tensile strength.
The same test was performed at 250 ° C., but after setting the sample in an atmosphere at 250 ° C., a tensile test was performed 20 seconds after the lowered temperature returned to 250 ° C.

"HR"
From the TS _R and TS _H, was determined as _{HR = TS H / TS R ×} 100. For example, the TS _R of the wire W having a diameter of 20μm in Example 1 in Table 1 234MPa, TS _H is 143MPa, HR becomes 143/234 × 100 = 61% .

"Loop height h"
In a flat bond in which the heights of the 1st junction and the 2nd junction are the same, the height h up to the highest point wire is expressed with reference to the ground point of the 1st junction and the 2nd junction (see FIG. 5). When the height h is 3 to 5 times the wire diameter L, the low loop is set, and when the height h is 10 times or more, the high loop is set. In Table 1, “low” and “high” are set, respectively.

“Continuous bonding”
Bonding machine performs 10,000 continuous bonding, "A" if no machine stop occurs, "B" if one machine stop occurs, "D" if more than one machine stop occurs It was. At this time, if the stage temperature is lowered, the continuous bonding becomes difficult. Therefore, it was performed at two levels of 200 ° C. (± 5 ° C.) and 150 ° C. (± 5 ° C.).

"Si chip damage at 1st junction"
After bonding, in order to evaluate Si chip damage directly under the 1st junction, the 1st junction and the electrode film were dissolved in aqua regia, and cracks of the Si chip were observed with an optical microscope and a scanning electron microscope (SEM). At this time, when 100 joints were observed and one or no minute pits of 5 μm or less were observed, “A” was indicated, and when cracks of 5 μm or more were observed, “D” was assigned.

"Wire feedability"
The finished product was wound up about 500 m on a spool to be attached to the bonding apparatus, and the spool was rotated in a direction opposite to the winding direction, whereby the wire W was naturally dropped and the wire feeding property was evaluated. Assume that the distance from the spool to the grounding point when naturally dropping is 1 m, and during 500 m of natural dropping, “A” if the wire is caught 2 times or less, and if it is 3 times or more, it is judged that there is a problem in use. Was “D”.

"Loop shape (with or without cracks)"
The loop after bonding was confirmed with a scanning electron microscope (SEM), and judged by the presence or absence of cracks on the wire surface. If the wire surface is smoothly arced and no cracks are generated, the evaluation is “A”. If the crack is 3% or more of the wire diameter, it is judged that there is a problem in use. D ".

"Comprehensive evaluation"
Evaluation of “continuous bondability” is “A” for both 200 ° C. and 150 ° C., and evaluation of “Si chip damage at 1st junction”, “wire unwinding property” and “loop shape” are all “A”. “A” for the case, “A” for “continuous bonding” at 200 ° C., “B” for 150 ° C., and “B” for all other evaluations “A” did. Further, one of the other evaluations having “D” is “D” because it is a practical problem.

From this test result, when the coating layer thickness (film thickness) t ₂ is less than 0.010 μm, both continuous bonding properties at 200 ° C. and 150 ° C. are lowered (Comparative Examples 4 and 9), and 0.01 μm or more and 0.0. When the thickness is less than 040 μm, the former continuous bonding property is satisfactory (Examples 4 to 6, 8, 11 to 13, Comparative Example 8), and when it is 0.040 μm or more, both continuous bonding properties are satisfactory. (Examples 1-3, 7, 9, 10, 14-16, Comparative Examples 1, 2, 5, 6). However, even if the coating layer thickness t ₂ is 0.040 μm or more, if the thickness t ₃ of the carbon enriched layer 3 exceeds 0.0005 μm, both continuous bonding properties at 200 ° C. and 150 ° C. are deteriorated (Comparative Example 7).

On the other hand, when the coating layer thickness _{t 2} exceeds 0.090, the ball b is harder, so damage to the Si chip (electrode a) is observed (Comparative Example 1～3,5～7).

If the thickness _{t 3} of the carbon concentration layer 3 is less than 0.0001micrometer, wire W is generated is caught without fed normally (Comparative Examples 5 and 6), can be fed out without problems in the above 0.0001micrometer (Examples 1-15, Comparative Examples 1-4, 7-9).
However, since a pulling force is applied from the bonding device to the wire W pulled out from the spool during connection by the ball bonding method, even if “D” in the above “wire unwinding property” is a problem, There may be no. In this case, as shown in Example 16, even when there is almost no carbon enriched layer 3 (thickness t ₃ ≈0.00), the thickness t ₂ of the coating layer 2 is 0.010 to 0.090 μm, and HR is 50 If it is ˜70%, since “A” is obtained in other evaluations, the wire W can be used.

Further, when the HR is less than 50%, as shown in the photograph of FIG. 2B showing the HR: 45% (Comparative Example 8), the copper crystal structure is a fiber structure in which processing strain remains (crystal structure with little softening). When the ball b is formed on the wire W by the discharge rod g shown in FIG. 3 (h), the crystal structure of copper is coarsened and the boundary of the crystal structure is formed. (Comparative Examples 5 and 8), when it exceeds 70%, the crystal structure of copper is coarsened (over-softened crystal structure) as shown in the photograph of FIG. 2 (c) showing HR: 71% (Comparative Example 9). (Large secondary recrystallized structure)) When the loop is high, there is a problem of cracking in the loop shape (Comparative Example 4), and even when the loop is low, breakage may occur and the continuous bonding property may be impaired. (Comparative Examples 7 and 9).
On the other hand, when the HR is 50 to 70%, as shown in the photograph of FIG. 2A showing the HR: 65% (Example 9), a good recrystallized structure is obtained, and the fiber structure and Since the boundary of the coarsened secondary recrystallized structure is less likely to occur, cracks did not occur from the crystal grain boundaries during the soldering (Examples 1 to 16 and Comparative Examples 1 to 3 and 6).

W Bonding wire 1 Core material 2 Coating layer 3 Carbon enriched layer a Electrode b of integrated circuit element b Bonding ball c Conductor wiring of circuit wiring board

Claims (3)

A bonding wire (W) having a wire diameter (L) of 50.8 μm or less for connecting an electrode (a) of an integrated circuit element and a conductor wiring (c) of a circuit wiring board by a ball bonding method. ) Is made of copper having a purity of 99.99% by mass or more and inevitable impurities, and a coating layer (2) having a thickness (t ₂ ) of 0.010 to 0.090 μm is formed on the entire outer periphery of the core material (1). The tempering heat treatment is performed at a furnace temperature of 400 ° C. to 800 ° C. and a wire traveling speed of 30 to 90 m / min. Tensile strength (TS _R ) by a tensile test at room temperature and a tensile test at 250 ° C. The ratio (HR = TS _H / TS _R × 100) to the tensile strength (TS _H ) by 50 was 50 to 70%, and the recrystallized structure of the core material (1) made of copper was coarsened. The boundary of secondary recrystallization structure is less likely to occur Bonding wires, wherein the door. The carbon concentration layer (3) having a carbon concentration of 1 to 80% by mass is provided on the outer peripheral portion of the coating layer (2), and the thickness (t ₃ ) of the carbon concentration layer ( ₃ ) is 0.0001 to 0.0005 μm. The bonding wire according to claim 1, wherein:   It is a manufacturing method of the bonding wire (W) of Claim 2, Comprising: Pd is coat | covered to the core material (1) which consists of the said copper of 99.99 mass% or more and an unavoidable impurity, The diffusion heat processing is carried out to the covered wire | wire. Is applied to improve the adhesion between the core material (1) and the coating layer (2), and then a lubricant is applied and the wire is drawn. And the carbon concentration layer (3) made of the lubricant is formed on the surface of the coating layer (2) by adjusting the degree of cleaning in the cleaning step.