TWI466750B - Welding needle - Google Patents

Description

Solder pin

The aspect of the invention relates to a bonding capillary, and in particular to a soldering pin in a case where bonding is performed by a hard bonding wire such as copper.

In a wire bonding in which a semiconductor element and a lead of a lead frame are bonded by a thin metal wire, one end of the thin metal wire (bonding wire) is crimped using a soldering pin. An electrode pad (first bond), followed by a crimped metal wire crimped to the wire (second bond). When crimping the thin metal wire, by pressing through the soldering pin Ultrasonic waves are applied in the state of the thin metal wires to achieve a reliable crimping.

In recent years, attempts have been made to increase the cost of materials for wire bonding to copper that is lower than gold. However, in the joining of the copper wires, since the copper wires are hard, it is difficult to obtain high joint strength, and the tip end portion of the solder pins is easily worn. Therefore, there is a problem that the frequency of replacement of the solder pins becomes higher as compared with the case of using gold wires.

Patent Document 1 discloses a welding pin which can reduce the adhesion of the tip end surface and extend the life by forming a convex and concave having a roundness on the tip end surface of the welding pin. Further, Patent Document 2 discloses that a solder needle which can extend the life is a particle which is exposed to a part of the tip end portion of the welding pin. The composition of the structure.

However, in any of the techniques of Patent Documents 1 and 2, there is still room for improvement in terms of improving the grip force of the bonding wire or maintaining the initial bonding strength for a long period of time. In particular, when a bonding wire which is harder than a gold wire such as a copper wire is used, the problem of a decrease in joint strength or a decrease in life due to abrasion becomes remarkable.

[Patent Document 1] Japanese National Publication No. 62-190343

[Patent Document 2] Japanese National Patent Publication No. 2009-540624

The present invention has been made in recognition of such a problem, and an object thereof is to provide a welding pin which can maintain sufficient joint strength for a long period of time.

According to a first aspect of the invention, a welding pin includes: a main body portion having a top end surface of a wire bonding, wherein the distal end surface has a fine uneven shape, and a tip end of the convex portion of the uneven shape is larger than a concave portion of the uneven shape The tip end of the tip is small, and the area of the convex portion when viewed in a direction perpendicular to the distal end surface is larger than the area of the concave portion, and the skewness of the distal end surface is -0.3 or less, and the average height of the distal end surface is It is 0.06 micrometer or more and 0.3 micrometer or less.

According to the welding pin, the initial bonding strength can be ensured, and the bonding strength can be maintained for a long period of time even if the bonding is repeated.

Further, a second aspect of the invention provides a welding pin comprising: a main body portion having a top end surface of a wire bonding, wherein the distal end surface has a fine uneven shape, and a tip end of the convex portion of the uneven shape is larger than a tip end of the uneven shape The tip end of the recess is small, perpendicular to the aforementioned tip end surface The area of the convex portion when viewed in the direction is larger than the area of the distal end of the concave portion, the skewness of the distal end surface is -0.43 or less, and the average height of the distal end surface is 0.16 μm or more and 0.3 μm or less.

According to the welding pin, since the contact area with the wire increases and the inclination becomes steep toward the concave portion, the gripping force between the tip end surface and the bonding wire increases.

According to this welding pin, the shape change accompanying abrasion during use is small, and the initial joining strength can be maintained for a long period of time even if the joining is repeated.

Further, the third invention is a welding pin, and in the first invention or the second invention, the maximum peak height of the distal end surface is 0.9 times or less of the average height.

According to this welding pin, the shape change accompanying abrasion during use is small, and the initial joining strength can be maintained for a long period of time even if the joining is repeated.

Further, the fourth invention is a welding pin, and in the first invention or the second invention, the mean particle size of the crystal exposed on the distal end surface is 1.2 μm or less.

According to the welding pin, if the average particle diameter of the crystal of the ceramic is 1.2 μm or less, the abrasion of the tip end surface can be reduced.

According to a fifth aspect of the invention, in the first aspect of the invention, the main body portion includes: a hole disposed on the distal end surface side, through which the bonding wire is inserted, and the hole and the tip end surface In the chamfer part, the uneven shape of the distal end surface is obtained by a surface of the chamfered portion at least 20 micrometers in a direction away from the hole along the distal end surface of the distal end surface. By being at least 100 micrometers in length The roughness curve of the meter measurement was obtained.

According to the welding pin, each of the first to fifth inventions can be sufficiently maintained for a long period of time if it is a concave-convex shape obtained by a roughness curve measured at least 100 μm in the surface region. Joint strength.

According to the aspect of the invention, it is possible to provide a welding pin which can maintain sufficient joint strength for a long period of time.

10‧‧‧ Body Department

11‧‧‧Cylinder

11h‧‧‧ hole

12‧‧‧Cone

13‧‧‧ Bottleneck

13c‧‧‧Chamfering

50, 51, 52‧ ‧ top surface

50r‧‧‧Surface area

110‧‧‧ soldering needle

200‧‧‧ wire

BW‧‧‧metal wire

CIR‧‧‧ Round

Cpk‧‧‧Process Capability Index

L1‧‧‧ length

L2‧‧‧Measure length

Rc‧‧ average height

Rp‧‧‧Maximum peak height

Rsk‧‧‧ skewness

Fig. 1 is a schematic view showing a welding pin according to the embodiment.

Fig. 2 is an enlarged plan view showing a mode of a tip shape of a welding pin according to the embodiment.

Fig. 3 is an enlarged plan view illustrating a mode of a tip end surface of a welding pin according to the embodiment.

Fig. 4 is a cross-sectional view showing a mode of a state in which wire bonding is performed.

Figs. 5(a) and 5(b) are views for explaining the uneven shape of the distal end surface of the embodiment.

6(a) and 6(b) are diagrams illustrating the concavo-convex shape of the distal end surface of the reference example (the first).

7(a) and 7(b) are diagrams illustrating the concavo-convex shape of the distal end surface of the reference example (the second).

Fig. 8 is a view showing evaluation results of Examples and Comparative Examples.

Fig. 9 is a perspective view illustrating a mode of a measurement area.

Fig. 10 is a view showing the result of determination of the joint strength.

Figures 11(a) and (b) are diagrams showing changes in Cpk due to the number of joints.

12(a) and (b) are diagrams illustrating a part of a method of manufacturing a welding pin.

Fig. 13 is a view exemplifying a method of measuring the average particle diameter of crystals of ceramics.

Fig. 14 is a view exemplifying the relationship between the average particle diameter of the crystal of the ceramic and the life.

Hereinafter, the embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

(embodiment)

Fig. 1 is a schematic view showing a welding pin according to the embodiment.

Fig. 2 is an enlarged plan view showing a mode of a tip shape of a welding pin according to the embodiment.

Fig. 3 is an enlarged plan view illustrating a mode of a tip end surface of a welding pin according to the embodiment.

The entirety of the welding pin 110 is shown in FIG. FIG. 2 shows an enlarged view of the portion A shown in FIG. 1. In Fig. 3, there is shown a perspective view of the tip end face viewed obliquely.

As shown in FIG. 1, the welding pin 110 includes a body portion 10 having a top end face 50. The main body portion 10 includes a cylindrical portion 11 having a diameter for mechanically fixing to the joint device, and a circle disposed on the tip end side of the cylindrical portion 11 The tapered portion 12; the neck portion 13 for joining at a position to be aimed away from the adjacent thin metal wire. The distal end surface 50 is an end surface on the distal end side of the neck portion 13.

Inside the welding pin 110, a hole for inserting a thin metal wire (welding wire) is provided through the axial direction. The cylindrical portion 11 has a diameter that can be mechanically fixed to the engagement device. The diameter of the conical portion 12 becomes smaller toward the distal end side. The conical portion 12 has, for example, a truncated cone shape, and the diameter on the side of the cylindrical portion 11 is substantially equal to the diameter of the cylindrical portion 11.

As shown in FIG. 2, the neck portion 13 is disposed on the side where the conical portion 12 is joined. The neck portion 13 has a diameter that can be wire-bonded at a predetermined joint position, such as avoiding adjacent thin metal wires that have been wired. For example, the diameter of the neck portion 13 gradually decreases from the root side (the conical portion 12 side) toward the distal end surface 50 side. In particular, the diameter of the root side becomes smaller.

By making the outer diameter of the neck portion 13 thin, it is possible to perform a high-density wire bonding in which the pitch of the joint position is as small as, for example, 50 μm or less. In other words, if the diameter of the neck portion 13 is made small, even if the interval of the joint position is narrow (in the case of performing high-density wire bonding), the adjacent thin metal wire and the neck portion 13 which have been wired can be prevented. Interference.

As shown in FIG. 3, a hole 11h through which the bonding wire is inserted is provided on the tip end surface 50 side of the welding pin 110. A chamfered portion 13c is provided between the hole 11h and the tip end surface 50. The chamfered portion 13c has a surface that is provided, for example, in a curved shape from the edge of the hole 11h to the tip end surface 50.

Figure 4 is a cross-sectional view illustrating a mode of the state of wire bonding Surface map.

A state of second bonding is shown in FIG.

The bonding wire (hereinafter referred to as a metal wire) BW inserted into the hole 11h of the welding pin 110 is subjected to the first bonding. Then, the soldering pin 110 is pulled onto the wire 200 in a prescribed track to form a loop on the wire BW.

As soon as the solder pin 110 is pressed against the wire 200, the wire BW is sandwiched between the tip end face 50 and the wire 200. Since the distal end surface 50 is inclined to the chamfered portion 13c, the distance between the distal end surface 50 and the lead wire 200 is narrowed from the outer side to the inner side of the distal end surface 50. Therefore, the thickness of the metal wire BW sandwiched between the tip end face and the wire 200 is thinned from the outer side to the inner side of the tip end face 50. The metal wire BW is separated at the position of the edge of the chamfered portion 13c.

In a state in which the metal wire BW is sandwiched between the tip end surface 50 and the wire 200, for example, ultrasonic waves are applied to the welding pin 110. Accordingly, the wire BW is crimped to the wire 200. After the metal wire BW is crimped, the solder pin 110 is raised. Accordingly, a metal wire BW is connected between the electrode pad and the wire 200.

In such wire bonding, since the welding pin 110 applies ultrasonic waves in a state where a pressing force is applied to the wire BW, the gripping force between the tip end surface 50 and the wire BW becomes important. As the gripping force is weakened, ultrasonic vibration cannot be effectively applied between the wire BW and the wire 200, and the bonding force of the wire BW and the wire 200 is easily weakened.

On the other hand, if the pressing force or the ultrasonic amplitude is increased to secure the joining force, the tip end surface 50 is easily worn. If the tip end face 50 is worn out and the desired gripping force is not obtained, it is necessary to replace the welding pin 110. If the frequency of replacement of the welding pin 110 is high, the bonding must be stopped frequently. Set, will give the impact of manufacturing time.

As shown in FIG. 3, the tip end surface 50 of the welding pin 110 according to the present embodiment has a fine uneven shape. The tip end of the convex portion in the uneven shape is smaller than the tip end of the tip end of the concave portion in the uneven shape. Accordingly, the required grip force in the welding pin 110 is maintained for a long period of time.

Here, the uneven shape of the tip end surface will be described.

Figs. 5(a) and 5(b) are views for explaining the uneven shape of the distal end surface of the embodiment.

6(a) and 6(b) are diagrams illustrating the concavo-convex shape of the distal end surface of the reference example (the first).

7(a) and 7(b) are diagrams illustrating the concavo-convex shape of the distal end surface of the reference example (the second).

In FIGS. 5 to 7, (a) is a measured value of a concavo-convex shape obtained by a three-dimensional scanning electron microscope showing a distal end surface, and (b) is an image showing a roughness curve.

The uneven shape of the tip end surface is represented by, for example, an average height Rc and a skewness (twist) Rsk.

The average height Rc and the skewness Rsk are calculated in accordance with JIS B 0601-2001.

In the present embodiment, the roughness curve of the tip end surface was measured by the following conditions.

Measuring machine: Laser microscope (Olympus Corporation, OLS4000)

Measuring magnification: 50 times

Cut off (phase compensated high-pass filter) λ c: 25 μm

From the roughness curve measured by the above-described conditions, the average height Rc is obtained by the following formula (1), and the skewness Rsk is obtained by the following formula (2).

In the formula (1), m is the number of contour curve elements, and Zti is the average value of the heights of the contour curve elements.

In the formula (2), Zq is the root mean square height, and Zn is the value of the height in the roughness curve.

The average height Rc of the distal end surface 50 of the present embodiment shown in Figs. 5(a) and 5(b) is 60 nanometers or more, and the skewness Rsk is about -1.2 or more and 0.3 or less.

The average height Rc of the distal end surface 51 of the reference example (1) shown in Figs. 6(a) and (b) is 10 nm to 15 nm, and the skewness Rsk is 0.3 to -0.5.

The average height Rc of the distal end surface 52 of the reference example (the second) shown in Figs. 7(a) and (b) is 150 nm to 280 nm, and the skewness Rsk is 0.2 to -0.25.

As described above, the skewness Rsk of the distal end surface 50 of the present embodiment is -0.3 or less. Moreover, the skewness Rsk can be -1.2 or more. Skewness Rsk is a symmetry of a mountain (convex) and a valley (concave) indicating a concavo-convex shape. If the concavo-convex shape is a sine distribution, the skewness Rsk becomes zero. The fact that the skewness Rsk is negative means that the area of the mountain (convex) when viewed in the direction perpendicular to the distal end surface 50 is larger than the area of the valley (concave) (the tip end of the convex portion is smaller than the tip end of the concave portion).

In the welding pin 110 of this embodiment having the distal end surface 50, the initial joint strength and the life are good. On the other hand, in the welding pin having the tip end surface 50 of the reference example (the first), the initial joint strength was insufficient. Further, in the welding pin having the distal end surface 52 of the reference example (the second), although the initial bonding strength is good, the life is short.

The tip end of the convex portion in the uneven shape of the distal end surface 50 can be made smaller than the tip end of the distal end of the concave portion in the uneven shape to ensure the initial joint strength, and the joint strength can be maintained for a long period of time even if the joint is repeated.

Further, the skewness Rsk of the distal end surface 50 is negative, and since the area of the mountain (convex) is larger than the area of the valley (concave), the contact area between the distal end surface 50 and the metal wire BW is increased, and the surface is steep toward the concave portion. The inclination is increased, so that the grip force between the tip end face 50 and the wire BW is increased.

In other words, in the welding pin 110 having the tip end surface 50, the initial bonding strength can be sufficiently ensured, and a long-life product excellent in abrasion resistance can be realized. In the case of the bonding pin 110 of the present embodiment, even when bonding is performed using a hard metal wire BW such as copper, sufficient bonding strength can be obtained. Further, since the end surface 50 is excellent in wear resistance, even if the hard metal wire BW such as copper is repeatedly used for connection, The initial joint strength is also maintained for a long time.

(Example)

Next, an embodiment of the welding pin 110 according to the present embodiment will be described.

Fig. 8 is a view showing evaluation results of Examples and Comparative Examples.

Fig. 9 is a perspective view illustrating a mode of a measurement area.

The average height Rc, the skewness Rsk, and the maximum peak height Rp of the tip end faces of Examples 1 to 6 and Comparative Examples 1 to 8 are shown in Fig. 8 .

The average height Rc, the skewness Rsk, and the maximum peak height Rp in each example are values measured by the surface area 50r shown in Fig. 9. That is, as shown in FIG. 9, the surface region 50r is a region in the direction of the direction L1 in the direction in which the edge of the chamfered portion 13c is separated from the hole 11h by the edge of the chamfered portion 13c. The length L1 is at least 20 μm. The measurement length L2 is about 100 μm in the range of the surface region 50r. In the present embodiment, the line roughness at a measurement length L2 of 100 μm is measured at three places in the surface region 50r, and the average is obtained.

The Cpk of the joint strength shown in Fig. 8 is a process capability index. In each of the examples shown in FIG. 8, when the average of the joint strength of the metal wire BW is Ave, and the lower limit of the joint strength is 3 gram (gf), Cpk=(Ave-3gf)/3 σ is calculated. . The joint strength is the strength under a pull test in the second weld. The number of samples is 30. The Cpk of the joint strength in the wire bonding is generally found to be 1.67 or more.

As shown in FIG. 8, in Examples 1 to 6 and Comparative Examples 1 to 8, the combinations of the average height Rc, the skewness Rsk, and the maximum peak height Rp were different. In Examples 1 to 6 and Comparative Examples 4 to 8, the Cpk of the joint strength was 1.67 or more.

Fig. 10 is a view showing the result of determination of the joint strength.

In the examples shown in FIG. 8 , the results of the joint strength determination are shown in Examples 1 to 6 and Comparative Examples 4 to 6 in which the Cpk of the joint strength is 1.67 or more.

The joint strength determination is performed for the initial Cpk, the number of wire bonding times of 500,000 times, and the Cpk of 1 million times, depending on whether or not each Cpk is lower than 1.67. In the joint strength determination of FIG. 10, [OK] is displayed when each Cpk is 1.67 or more, and [NG] is displayed when it is less than 1.67.

As shown in FIG. 10, in Examples 1 to 6 and Comparative Examples 4 to 6, the initial joint strength determination was [OK]. After the wire bonding was performed 500,000 times, although Examples 1 to 6 were [OK], Comparative Examples 4 to 6 were both [NG]. After 1 million wire bonding, Examples 1 to 3, 5, and 6 were [OK], and Example 4 and Comparative Examples 4 to 6 were [NG]. After the wire bonding was performed 1.5 million times, Examples 5 and 6 were [OK], and Examples 1 to 4 and Comparative Examples 4 to 6 were [NG].

Figures 11(a) and (b) are diagrams showing changes in Cpk due to the number of joints.

Fig. 11(a) shows changes in Cpk in the second embodiment shown in Figs. 8 and 10, and Fig. 11(b) shows changes in Cpk in the comparative example 6 shown in Figs. 8 and 10.

As shown in Fig. 11 (a), the welding pin having the tip end surface of Example 2 maintains the initial bonding strength even if it exceeds 1,000,000 times from the initial stage of bonding, and the Cpk of 1.67 or more continues.

On the other hand, as shown in Fig. 11 (b), the welding needle having the tip end surface of Comparative Example 6 has a Cpk of 1.67 or more at the initial stage of bonding, but a significant decrease in Cpk is observed from more than 300,000 times. Below 1.67.

As a result of the above, the skewness Rsk of the distal end surface 50 is about -1.2 or more and 0.3 or less, and the average height Rc of the distal end surface 50 is preferably 0.06 μm or more and 0.3 μm or less. When the average height Rc is not 0.06 μm or more, the gripping force is small, and in particular, in the case of using the metal wire BW of the copper wire, sufficient joint strength cannot be obtained. Further, when the average height Rc exceeds 0.3 μm, it becomes difficult to form irregularities having a skewness of Rsk-0.3 or less. Further, it is more preferable that the skewness Rsk of the distal end surface 50 is about -1.2 or more to 0.43 or less, and the average height Rc of the distal end surface 50 is 0.16 μm or more and 0.3 μm or less. According to this, the initial bonding strength can be maintained even after 1.5 million times from the initial stage of bonding.

Further, it is preferable that the maximum peak height Rp of the distal end surface 50 is 0.9 times or less (Rp/Rc ≦ 0.9) of the average height Rc. Moreover, Rp/Rc can be 0.5 times or more. When Rp/Rc exceeds 0.9, it is difficult to maintain the initial bonding strength for a long period of time. On the other hand, when Rp/Rc is 0.9 or less, the shape change accompanying abrasion during use is small, and the initial joint strength is maintained for a long period of time.

(Production method)

Next, a method of manufacturing the welding pin 110 according to the present embodiment will be described.

12(a) and (b) are diagrams illustrating a part of a method of manufacturing a welding pin.

The procedure for forming the uneven shape of the distal end surface 50 in the method of manufacturing the welding pin 110 is shown in FIGS. 12(a) and (b).

The material of the welding pin 110 according to the present embodiment includes, for example, aluminum (Al ₂ O ₃ ) and zirconia (ZrO ₂ ). As shown in Fig. 12 (a), ZrO _{2 having a} small particle diameter is dispersed in the welding pin 110 in Al ₂ O _{3 having a} large particle diameter. When the tip end surface 50 is polished, the crystal of the ZrO ₂ is exposed on the surface of the Al ₂ O ₃ base material at the tip end surface 50.

In this state, the top end surface 50 is subjected to sandblasting. An example of the conditions of sand blasting is the type of abrasive grain, the spray pressure, and the spraying time. By optimizing the conditions of blasting, the crystal of ZrO ₂ softer than Al ₂ O ₃ is detached from the surface of the Al ₂ O ₃ parent material. As a result, as shown in FIG. 12(b), a concave portion is formed in a part of the flat surface of the distal end surface 50. At this time, since the ratio of ZrO ₂ to the Al ₂ O ₃ base material is small, the area of the concave portion formed by the crystal falling of ZrO ₂ is not larger than the area of the convex portion (flat surface).

Further, the above-described production method is an example, and a method other than sand blasting can also be produced.

(crystal size)

Next, the crystal grain size of the welding pin will be described.

In the welding pin 110 according to the present embodiment, the average crystal grain size of the ceramic exposed on the distal end surface 50 is 1.2 μm or less. Further, the average crystal grain size of the ceramic crystals can be 0.3 μm or more. When the average particle diameter of the crystal of the ceramic is 1.2 μm or less, the abrasion of the tip end surface 50 is reduced, and the life of the welding pin 110 is prolonged.

Figure 13 is a graph illustrating the average particle diameter of crystals of ceramics. A diagram of the method.

In the SEM (Scanning Electron Microscope) image in which the surface of the sample made of the ceramic is polished, and the boundary between the particles is made clear, thermal etching is applied.

First, an arbitrary portion of the sample was observed by SEM at a magnification of about 10,000 times to 30,000 times to obtain an SEM image. Then, the average particle diameter is calculated based on the obtained SEM image by, for example, a planimetric method.

The calculation of the average particle diameter was carried out by the following procedure.

First, a known circle CIR of the area A (μm ² ) is drawn on the acquired SEM image. Next, the number nc of particles contained inside the circle CIR and the number ni of particles falling above the circle CIR (on the circumference) are calculated. Then, using nc and ni, the average particle diameter was calculated by the following formula.

N=(nc+(1/2)ni/(A/magnification ² )

Average particle size (μm) = 2 / (π. N) ^1/2

Fig. 14 is a view exemplifying the relationship between the average particle diameter of the crystal of the ceramic and the life.

FIG. 14 shows the results of determination of the average particle diameter of the number of types for the life of the welding needle due to the number of joints. The number of joints is 500,000 times and 1 million times. When the life is judged, [OK] is displayed if Cpk is 1.67 or more, and [NG] is displayed if it is less than 1.67.

As a result of the results shown in Fig. 14, even in the number of joints of 500,000 times, in order to maintain Cpk of 1.67 or more, the average crystal grain size of the ceramic is preferably about 0.3 μm or more and 1.2 μm or less. And better average particle size It is about 0.3 μm or more and 0.7 μm or less. When the average particle diameter is 0.7 μm or less, the Cpk of 1.67 or more is maintained even in the number of times of bonding of 1 million times.

When the welding pin 110 is formed of such a ceramic having an average particle diameter, the wear of the tip end surface 50 is reduced. Accordingly, the life of the welding pin 110 becomes long, and the reduction in the frequency of replacement is achieved.

As described above, according to the present embodiment, sufficient bonding strength between the metal wire BW and the wire 200 can be obtained in the wire bonding, and the initial bonding strength can be maintained for a long period of time even when the bonding is repeated.

The embodiments of the present invention have been described above. However, the present invention is not limited to the descriptions. With regard to the above-described embodiments, it is within the scope of the present invention to incorporate design changes as appropriate to those skilled in the art. For example, the shape, size, material, and the like of the welding pin 110 are not limited to those exemplified, and can be appropriately changed.

10‧‧‧ Body Department

11‧‧‧Cylinder

12‧‧‧Cone

13‧‧‧ Bottleneck

50‧‧‧ top surface

110‧‧‧ soldering needle

Claims (7)

A welding pin characterized by comprising: a main body portion having a top end surface of a wire bonding, the top end surface having a fine concavo-convex shape, wherein a tip end of the convex portion in the concavo-convex shape is smaller than a tip end of the concave portion in the concavo-convex shape The area of the convex portion when viewed in a direction perpendicular to the distal end surface is larger than the area of the concave portion, the deflection of the distal end surface is -0.3 or less, and the average height of the distal end surface is 0.06 μm or more and 0.3 μm or less. . A welding pin characterized by comprising: a main body portion having a top end surface of a wire bonding, the top end surface having a fine concavo-convex shape, wherein a tip end of the convex portion in the concavo-convex shape is smaller than a tip end of the concave portion in the concavo-convex shape The area of the convex portion when viewed in a direction perpendicular to the distal end surface is larger than the area of the concave portion, the deflection of the distal end surface is -0.43 or less, and the average height of the distal end surface is 0.16 μm or more and 0.3 μm or less. . For example, in the welding pin of claim 1 or 2, the maximum peak height of the top surface is 0.9 times or less of the average height. The welding pin of claim 1 or 2, wherein the average particle diameter of the crystal exposed on the tip end surface is 1.2 μm or less. The welding pin of claim 1 or 2, wherein the body portion has: a hole disposed on the top end side, a hole through which the bonding wire is inserted, and a chamfer disposed between the hole and the top end surface The concave-convex shape of the top end surface is determined by a length of at least 100 μm in a surface area of the top end surface at least 20 μm from an edge of the chamfered portion along the direction of the end surface from the hole. The roughness curve is obtained. A soldering needle according to item 3 of the patent application, wherein an average particle diameter of the crystal exposed on the tip end surface is 1.2 μm or less. The soldering needle according to the third aspect of the invention, wherein the main body portion has: a hole disposed on the distal end surface side, a hole through which the bonding wire is inserted, and a chamfered portion provided between the hole and the top end surface, the top end The concavo-convex shape of the face is in a surface region of the tip end face that is at least 20 microns in a direction away from the hole along the edge of the chamfered portion, by a roughness curve measured by a length of at least 100 microns Find out.