KR20160002343A - Bonding capillary - Google Patents

Abstract

The present invention is to improve bonding strength while preventing a crack from being generated on a bonding wire. A bonding capillary according to an embodiment comprises a pressure surface which pressurizes a bonding wire, an insertion through hole which the bonding wire is inserted into and penetrates through, a taper-shaped hole which connects the insertion through hole and the pressure surface, and becomes wider toward the pressure surface, and a chamfer part which is formed between the taper-shaped hole and the pressure surface. The chamfer part has a convexo-concave surface. Also, a sharp degree of a convex part in the convexo-concave shape is less than that of a concave part in the convexo-concave shape.

Description

Bonding Capillary {BONDING CAPILLARY}

Embodiments of the disclosure relate to a bonding capillary.

Conventionally, wire bonding is known as a method for electrically connecting a semiconductor chip and a lead frame. The wire bonding is a method of electrically connecting the metal wires called bonding wires between the semiconductor chip and the electrodes of the lead frame by bridging them.

In the wire bonding, a tubular tool called a bonding capillary is used. Specifically, the capillary is protruded from the tip through a bonding wire to the inside of the bonding capillary, and the protruded bonding wire is pressed against the electrode using the tip end surface of the bonding capillary. Further, ultrasound is applied to the bonding capillary to vibrate the end surface to rub the bonding wire to the electrode. As a result, the bonding wire is bonded to the electrode.

As a bonding capillary, it is known that an R portion having a predetermined curvature is formed at the periphery of an opening of an insertion hole through which a bonding wire is inserted in order to prevent adhesion of a bonding wire to a tip end face (see, for example, Patent Document 1 Reference).

Japanese Patent Application Laid-Open No. 9-326411

However, there is a problem in that when the wire bonding is performed using the bonding capillary having the R portion, the bonding strength is hardly obtained. This is because the gripping force on the bonding wire is lowered by forming the R portion, and it becomes difficult to frictionally attach the bonding wire to the electrode.

The problem of such bonding strength becomes remarkable when wire bonding is performed using a bonding wire made of Al (aluminum). This is because Al is likely to be oxidized as compared with Au (gold), which is generally used as a material of a bonding wire, and bonding with an electrode is easily inhibited by an oxide film formed on the surface.

In addition, there is also a problem that cracks tend to occur in Al bonding wires compared with Au bonding wires. Therefore, when wire bonding is performed using an Al bonding wire, it is preferable to improve the bonding strength and to suppress the occurrence of cracks.

It is an object of the embodiment of the present invention to provide a bonding capillary capable of increasing the bonding strength while suppressing the occurrence of cracks in the bonding wire.

The bonding capillary according to an embodiment of the present invention includes a pressing surface for pressing a bonding wire, an insertion hole through which the bonding wire is inserted, and a connection surface between the insertion hole and the pressing surface, And a chamfered portion formed between the tapered hole and the pressing surface, wherein the chamfered portion has a concavo-convex shape on the surface, and the degree of sharpness of the convex portion in the concave- Is smaller than the degree of sharpness of the concave portion in the concave portion.

By forming the chamfered portion between the tapered hole and the pressing surface, the stress applied to the bonding wire can be relaxed, so that occurrence of cracks in the bonding wire can be suppressed. Further, by forming the concavo-convex shape on the surface of the chamfered portion, the gripping force against the bonding wire when rubbing the bonding wire onto the electrode can be improved, so that the bonding strength can be increased. On the other hand, there is a fear that the wire may be damaged by the sharpness of the convex portion in the concavo-convex shape only by forming the concave-convex shape, and the wire is liable to be cracked by the scratch. Thus, the degree of sharpness of the convex portion in the concave-convex shape is made smaller than the degree of sharpness of the concave portion. This makes it possible to suppress the occurrence of cracks due to the uneven shape.

The concavo-convex shape of the chamfered portion is characterized in that the degree of distortion is -0.164 or less and the average height is 0.035 mu m or more and 0.092 mu m or less.

This makes it possible to appropriately suppress the occurrence of cracks in the bonding wire after the first bonding process when wire bonding is performed using Al bonding wires. Further, sufficient bonding strength can be obtained in the tail portion after the second bonding process.

The pressing surface has a concavo-convex shape, and the degree of sharpness of the convex portion in the concavo-convex shape of the pressing face is larger than the degree of sharpness of the convex portion in the concavo-convex shape of the chamfered portion.

It is difficult for the pressing surface to generate cracks in the bonding wire as compared with the chamfered portion. For this reason, the pressing surface may be configured as described above from the viewpoint of improving the gripping force rather than preventing the occurrence of cracks. With this configuration, the gripping force on the bonding wire can be further improved.

In addition, the concavo-convex shape on the pressing surface has an average height of 0.113 mu m or more.

This makes it possible to obtain a sufficient bonding strength in the stitch portion after the second bonding process when wire bonding is performed using Al bonding wires.

The chamfered portion has a curved surface smoothly continuing to the tapered hole and the pressing surface, and the radius of curvature of the curved surface is not less than 4.55 mu m and not more than 20.30 mu m.

This makes it possible to appropriately suppress the occurrence of cracks in the bonding wire when wire bonding is performed using Al bonding wires. In addition, it is possible to appropriately suppress the occurrence of defective division of the bonding wire after the second bonding process.

The chamfered portion has a curved surface smoothly continuing to the tapered hole and the pressing surface, and the radius of curvature of the curved surface is not less than 12.8 탆 and not more than 20.30 탆.

Thus, even when the loop length of the bonding wire is 3 mm or more in the case of wire bonding using an Al bonding wire, occurrence of cracks in the bonding wire can be suitably suppressed. In addition, it is possible to appropriately suppress the occurrence of defective division of the bonding wire after the second bonding process.

The tapered hole has a taper angle of 100 DEG or less.

As a result, occurrence of cracks in the bonding wire at the boundary between the insertion hole and the tapered hole can be suitably suppressed.

The outer diameter of the pressing surface is not less than 4.0 times and not more than 5.7 times the wire diameter of the bonding wire.

Thus, desired bonding strength can be obtained.

(Effects of the Invention)

According to the embodiment of the embodiment, it is possible to increase the bonding strength while suppressing the occurrence of cracks in the bonding wire.

1 is a schematic side view showing a bonding capillary according to the present embodiment.
Fig. 2 is an enlarged view of the H1 portion shown in Fig.
Fig. 3 is a schematic cross-sectional view showing a tip end portion of the bottle neck portion.
Fig. 4 is an enlarged view of the H2 section shown in Fig. 3. Fig.
5 is a schematic side sectional view showing the surface shape of the pressing surface.
6 is a schematic side sectional view showing the surface shape of the chamfered portion.
7 is a schematic side cross-sectional view showing a form of the first bonding process.
8 is a schematic side cross-sectional view showing a mode of a second bonding process.
9 is a graph illustrating the roughness curve of the surface of the chamfered portion.
Fig. 10 is a diagram showing the evaluation results when the distortion and the average height of the concavo-convex shape in the chamfered portion and the average height of the concavo-convex shape in the pressing face are respectively changed.
Fig. 11 is a view showing the evaluation result when the radius of curvature of the chamfered portion is changed. Fig.
Fig. 12 is a diagram showing the evaluation result when the radius of curvature of the chamfered portion is changed. Fig.
Fig. 13 is a view showing the evaluation result when the angle of the tapered hole is changed. Fig.
14 is a schematic perspective view showing an example of a simulation result of bonding.
15 is a schematic plan view showing an example of a simulation result of bonding.
Fig. 16 is a view showing the evaluation result when the ratio of the outer diameter of the pressing surface and the wire diameter is changed.
17 is a flow chart illustrating a part of a manufacturing method of a bonding capillary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a bonding capillary disclosed by the present application will be described in detail with reference to the accompanying drawings. In addition, the present invention is not limited to the embodiments described below.

(Embodiments)

First, the entire configuration of the bonding capillary according to the present embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a schematic side view showing a bonding capillary according to the present embodiment. Fig. 2 is an enlarged view of the H1 portion shown in Fig. 1. Fig.

As shown in Fig. 1, the bonding capillary 1 (hereinafter referred to as capillary 1) according to the present embodiment has a structure in which a bonding wire (hereinafter referred to as " wire & And has an insertion hole (11). The capillary 1 is formed of, for example, ceramics. The material of the capillary 1 is, for example, alumina. Or a composite material containing at least one of alumina, zirconia and chromia as the material of the capillary (1).

The capillary (1) has a cylindrical portion (12), a conical portion (13) and a bottle neck portion (14). The conical portion 13 is a portion formed at one end of the cylindrical portion 12 and has a shape that is reduced in diameter toward the tip side. The bottle neck portion 14 is formed at the tip of the conical portion 13 and has a smaller diameter than the tip diameter of the conical portion 13. [ The insertion hole 11 is formed to penetrate the cylindrical portion 12, the conical portion 13, and the bottle neck portion 14. [

2, a tapered hole 20 is formed between the pressing surface 30 and the insertion hole 11, which is the front end surface of the bottle neck portion 14. As shown in Fig. The tapered hole 20 is tapered so as to be pushed toward the pressing surface 30 from the insertion hole 11. [

The capillary 1 constructed as described above presses the wire protruding outward from the tapered hole 20 to the electrode by using the pressing surface 30 and vibrates the pressing surface 30 by ultrasonic waves, Thereby bonding the wire to the electrode.

Here, Au (gold) is generally used as the material of the wire. On the other hand, Al (aluminum) is generally used for the pad electrode which is the electrode of the semiconductor chip. When Au and Al, which are different kinds of metals, are bonded to each other, voids are generated at the bonding interface, which may lower the bonding strength. In addition, there is also a problem that the manufacturing cost of the semiconductor device is increased by using Au of high price.

Therefore, in recent years, it has been proposed to use Al, which is the same material as the pad electrode of the semiconductor chip, and is less expensive than Au, as the material of the wire.

However, Al has a lower strength than Au. For this reason, there is a problem that after the first bonding step, which will be described later, a crack is likely to occur at the bent portion of the wire. Further, Al is easily oxidized as compared with Au, and the bonding with the electrode is likely to be inhibited by the oxide film formed on the surface. Therefore, there is also a problem that it is not easy to obtain sufficient bonding strength.

Thus, in the capillary 1 according to the present embodiment, by forming the chamfered portion at the boundary portion between the pressing surface 30 and the tapered hole 20, cracks in the bent portion of the wire are suppressed. In addition, in the capillary 1 according to the present embodiment, the chamfered portion is formed with a fine concavo-convex shape so that the pressing surface 30 is vibrated to improve the gripping force on the wire when the wire is frictionally attached to the electrode, To increase the bonding strength.

On the other hand, if only the uneven shape is formed, there is a fear that the wire is damaged by the sharp point of the convex portion in the uneven shape, and the wire is damaged, so that the wire tends to be easily cracked. Therefore, in the capillary 1 according to the present embodiment, the degree of sharpness of the convex portion in the concave-convex shape is made smaller than the degree of sharpness of the concave portion. This makes it possible to suppress the occurrence of cracks due to the uneven shape. The " sharpness degree " means the degree of sharpness of the convex portion and the concave portion. Therefore, "the degree of sharpness of the convex portion is made smaller than that of the concave portion" means that the sharpness of the convex portion is made gentler than the sharpness of the concave portion.

Hereinafter, the configuration of the chamfered portion formed at the boundary portion between the pressing surface 30 and the tapered hole 20 and the shape of the concave-convex portion formed on the surface of the chamfered portion will be described in detail with reference to Figs. 3 and 4. Fig. 3 is a schematic side cross-sectional view showing the distal end portion of the bottle neck portion 14. As shown in Fig. Fig. 4 is an enlarged view of the H2 section shown in Fig. 3. Fig.

As shown in Fig. 3, the pressing surface 30 is formed into a convex surface shape that slightly rises from the outer edge portion toward the center portion. Further, the tapered hole 20 is formed at the center of the pressing surface 30. [ Therefore, in the capillary 1, the boundary portion between the tapered hole 20 and the pressing surface 30 is the portion protruding to the tip endmost side, and the wire tends to crack in this portion.

The chamfered portion 40 is formed at the boundary portion between the tapered hole 20 and the pressing surface 30. 4, the chamfered portion 40 has a curved surface that smoothly continues from the tapered hole 20 to the pressing surface 30.

5 is a schematic side sectional view showing the surface shape of the pressing surface 30. Fig. 6 is a schematic side sectional view showing the surface shape of the chamfered portion 40. As shown in Fig. As shown in Figs. 5 and 6, the pressing surface 30 and the chamfered portion 40 are formed with fine irregularities on their surfaces. These concave and convex shapes are formed so that the degree of sharpness of the convex portions 31 and 41 becomes smaller than the degree of sharpness of the concave portions 32 and 42. [

The concavo-convex shape of the pressing surface 30 shown in Fig. 5 is set so that the degree of sharpness of the convex portion 31 becomes larger than the degree of sharpness of the convex portion 41 in the concavo-convex shape of the chamfered portion 40 shown in Fig. . Thus, in the capillary 1 according to the present embodiment, the gripping force of the pressing surface 30 with respect to the wire is made higher than the gripping force of the chamfered portion 40 with respect to the wire.

Next, the operation of the above-described structure will be described with reference to Figs. 7 and 8 together with the operation of the wire bonding. 7 is a schematic side cross-sectional view showing a form of the first bonding process. 8 is a schematic side cross-sectional view showing a mode of the second bonding process.

Wire bonding includes a first bonding process, a loop forming process, and a second bonding process. The first bonding step is a step of bonding wires to one of the electrodes. The loop forming process is a process of forming a loop of a wire between electrodes by moving the capillary 1 in a predetermined orbit after the first bonding process. The second bonding step is a step of bonding wires to the other electrode after the loop forming step. Through these processes, the wires are bridged between the electrodes, and the semiconductor chip and the lead frame are electrically connected.

Fig. 7 shows a case where wire bonding is performed using a wire made of Al (hereinafter referred to as " Al wire ") instead of a wire made of Au (hereinafter referred to as Au wire) And shows the form of the process.

Here, in wire bonding using a conventional Au wire, ball bonding is performed as a first bonding process. Ball bonding is a method of melting a tip of a wire by discharging to form a ball of Au, and bonding the wire and the electrode by thermocompression bonding the ball to the electrode. Bonding capillary is used for ball bonding.

On the other hand, when wire bonding is performed using an Al wire, it is difficult to perform the ball bonding described above. This is because Al is easily oxidized as compared with Au, and it is difficult to form a ball like Au. Therefore, when wire bonding is performed using an Al wire, a wedge bonding tool for bonding a wire to an electrode without forming a ball is generally used (see, for example, Japanese Patent Application Laid-Open No. 2001-156100).

However, since the wedge bonding tool is complicated in structure compared to the bonding capillary, it is expensive and has low durability. For this reason, in the present embodiment, the capillary 1, which is a bonding capillary having a lower cost and a higher durability than the wedge bonding tool, is used to perform the wire bonding by the Al wire. This makes it possible to increase the productivity of the semiconductor device.

As shown in Fig. 7, the capillary 1 first presses the Al wire W to the lead electrode 100 of one of the electrodes, for example, the lead frame, by using the pressing surface 30. Fig. At this time, a predetermined gap is formed between the chamfered portion 40 and the lead electrode 100 so that the Al wire W is not divided between the chamfered portion 40 and the lead electrode 100.

Subsequently, ultrasonic waves are applied to the cylindrical portion 12 (see Fig. 1) of the capillary 1. As a result, the pressing surface 30 is vibrated and the Al wire W rubs against the lead electrode 100. As a result, the Al wire W is bonded to the lead electrode 100.

Subsequently, the capillary 1 forms a loop of the wire by moving while drawing a predetermined trajectory. At this time, a boundary line of a portion of the Al wire W bonded to the lead electrode 100, for example, a region B shown in Fig. 7 is formed. Cracks are likely to occur in this bent portion.

As a countermeasure to this point, the chamfered portion 40 is formed at the boundary between the tapered hole 20 and the pressing surface 30 in the capillary 1 according to the present embodiment. As a result, the stress concentration on the region B is relaxed compared with the case where the chamfered portion 40 is not formed, so that occurrence of a crack in the bent portion of the Al wire W can be suppressed.

Further, as described above, there is also a problem that it is not easy to obtain a sufficient bonding strength as compared with the Au wire because the Al wire W tends to be hindered from bonding with the electrode due to the oxide film formed on the surface.

As a countermeasure to this point, in the capillary 1 according to the present embodiment, a fine uneven shape is formed on the surface of the chamfered portion 40. This improves the gripping force of the chamfered portion 40 with respect to the Al wire W, so that sufficient bonding strength can be obtained even in the case of using the Al wire W which is harder to obtain the bonding strength than the Au wire.

The concavo-convex shape of the chamfered portion 40 is formed such that the degree of sharpness of the convex portion 41 becomes smaller than the degree of sharpness of the concave portion 42. [ Therefore, with the capillary 1 according to the present embodiment, it is possible to obtain a high bonding strength while suppressing the occurrence of cracks due to the concavo-convex shape.

In the capillary 1 according to the present embodiment, the pressing surface 30 is also formed with a fine concavo-convex shape. It is difficult for the pressing surface 30 to generate a crack in the Al wire W as compared with the chamfered portion 40. [ Therefore, from the viewpoint of emphasizing the improvement of the gripping force rather than the prevention of the occurrence of cracks, the convexoconcave shape of the pressing face 30 is set such that the degree of sharpness of the convex portion 31 is smaller than that of the convex portion 41 in the concave- (See Figs. 5 and 6). As a result, the gripping force against the Al wire W can be further improved.

Subsequently, the capillary 1 performs a second bonding process. First, as shown in Fig. 8, the capillary 1 presses the Al wire W to the other electrode, for example, the pad electrode 200 of the semiconductor chip, by using the pressing surface 30. It is necessary to separate the Al wire W after bonding the Al wire W to the pad electrode 200 in the second bonding step. Therefore, the interval between the chamfered portion 40 and the pad electrode 200 is set shorter than that in the first bonding process.

Subsequently, the capillary 1 vibrates the pressing surface 30 by ultrasonic waves to rub the Al wire W to the pad electrode 200. As a result, the Al wire W is bonded to the pad electrode 200.

Subsequently, the capillary 1 is raised by a predetermined distance. At this time, as shown in Fig. 8, the Al wire W is not only stitch portion S outside the chamfered portion 40, but also the tail portion T inside the chamfered portion 40, It is in a state of being bonded. Therefore, when the capillary 1 rises, the Al wire W is drawn out from the capillary 1 in accordance with this rise. The drawn Al wire W becomes a portion to be bonded to the lead electrode 100 in the next first bonding process.

The Al wire W is divided between the stitch portion S and the tail portion T by, for example, moving the capillary 1 left and right.

As described above, in the second bonding process, it is necessary to temporarily bond the Al wire W to the pad electrode 200 in the tail portion T in order to pull out the Al wire W from the capillary 1 . However, since an oxide film is easily formed on the Al wire W as described above, it is not easy to secure the bonding strength of the tail portion T.

On the other hand, in the capillary 1 according to the present embodiment, since the chamfered portion 40 is formed with a fine concave-convex shape to improve the gripping force of the chamfered portion 40 with respect to the Al wire W, ), Sufficient bonding strength can be obtained.

The capillary 1 according to the present embodiment has the pressing surface 30, the insertion hole 11, the tapered hole 20 and the chamfered portion 40 as described above. The pressing surface 30 is the surface pressing the bonding wire. The insertion hole 11 is a hole through which the bonding wire is inserted. The tapered hole 20 is a hole that connects the insertion hole 11 and the pressing surface 30 and has a shape that widens toward the pressing surface 30. [ The chamfered portion 40 is formed between the tapered hole 20 and the pressing surface 30. The chamfered portion 40 has a concavo-convex shape on the surface, and the degree of sharpness of the convex portion 41 in the concavo-convex shape is smaller than the degree of sharpness of the concavity 42 in the concavo-convex shape.

Therefore, according to the capillary 1 according to the present embodiment, it is possible to increase the bonding strength while suppressing the occurrence of cracks in the bonding wire.

(Example)

Next, an embodiment of the capillary 1 according to the present embodiment will be described with reference to Figs. 9 to 11. Fig. 9 is a graph illustrating the roughness curve of the surface of the chamfered portion. Fig. 10 is a diagram showing the evaluation results when the distortion and the average height of the irregularities in the chamfered portion 40 and the average height of the irregularities in the pressing surface 30 are changed, respectively. 11 is a view showing an evaluation result when the radius of curvature of the chamfered portion 40 is changed.

The concavo-convex shape of the pressing face 30 and the chamfered portion 40 is represented by, for example, an average height Rc and a degree of deformation Rsk. The average height Rc and the distortion Rsk are calculated in accordance with JIS B 0601-2001.

The degree Rsk is a value indicating the symmetry of the convex portion and the concave portion in the concave-convex shape. If the concave / convex shape is symmetrical, the degree of distortion Rsk becomes zero. When the degree of distortion Rsk is negative, the degree of sharpness of the convex portion in the concavo-convex shape is smaller than that of the concave portion. In other words, when the concavo-convex shape is viewed from the plane, Which is larger than the area of the bottom portion.

In this embodiment, the roughness curves of the pressing surface 30 and the chamfered portion 40 were measured using a laser microscope (OLS4000 manufactured by OLYMPUS CORPORATION). The measurement conditions are as follows.

Measurement magnification: 50 times

Evaluation length (roughness measurement): 500 탆 to 800 탆

Cut-off (phase-compensation type high-pass filter) lambda c: 25 mu m

From the roughness curves measured under the above conditions, the average height Rc was determined by the following expression (1), and the degree of distortion Rsk was obtained by the following expression (2).

Here, in the formula (1), m is the number of contour curve elements, and Zti is an average value of the height of contour curve elements. In the equation (2), Zq is the root mean square height and Zn is the height value in the roughness curve.

An example of the roughness curve obtained by measuring the surface of the chamfered portion 40 with a laser microscope is as shown in Fig. In Fig. 9, the vertical axis indicates the height (micrometer: 占 퐉), and the horizontal axis indicates the measurement position (占 퐉). In the roughness curve shown in Fig. 9, the degree of distortion Rsk of the concave-convex shape of the chamfered portion 40 is -0.164, and the average height Rc of the concave-convex shape of the chamfered portion 40 is 0.073.

10 shows the relationship between "crack", "tail joint" and "tail joint" in the case where the root height Rsk of the chamfered portion 40, the average height Rc and the average height Rc of the pressing surface 30 are changed, Stitch bonding " shown in Fig.

Here, the item " crack " is an item indicating whether or not a crack has occurred in the Al wire W after the first bonding process. In this " crack " item, the case where no crack occurred is indicated as "? &Quot;. The items "tail joint" and "stitch joint" are items indicating whether or not sufficient bond strength is obtained in the tail portion T and the stitch portion S shown in FIG. 8 after the second bonding process. In these "tail joint" and "stitch joint" items, a case where sufficient bond strength is obtained is defined as "◯".

As shown in Fig. 10, in Comparative Examples 1 and 2, sufficient bonding strength could not be obtained in the tail portion T and the stitch portion S after the second bonding process. In Comparative Examples 3 to 6, cracks were generated in the Al wire W after the first bonding process.

On the other hand, in Examples 1 to 5, cracks were not generated in the Al wire W after the first bonding process, and sufficient bonding strength was obtained in the tail portion T and the stitch portion S after the second bonding process.

From this result, it is preferable that the shape of the concavities and convexities in the chamfered portion 40 have a deformation Rsk of -0.164 or less and an average height Rc of 0.035 mu m or more and 0.092 mu m or less. Further, the average height Rc of the concavo-convex shape on the pressing face 30 is preferably 0.113 mu m or more.

When the average height Rc of the chamfered portion 40 is set to 0.035 占 퐉 or more, for example, in a case where the degree of distortion Rsk of the concavo-convex shape in the chamfered portion 40 is less than -1.4, It is difficult. Therefore, it is preferable that the ruggedness Rsk of the chamfered portion 40 is -1.4 or more.

The average height Rc of the concavo-convex shape on the pressing surface 30 can be 4.642 mu m or less. When the average height Rc of the concavo-convex shape on the pressing surface 30 is higher than 4.642 占 퐉, the concavo-convex shape with the average height Rc of 0.092 占 퐉 or more after the chamfered portion 40 is formed remains in the chamfered portion 40 There is a case. Therefore, the average height Rc of the concavo-convex shape on the pressing surface 30 is preferably 4.642 占 퐉 or less. The average height Rc of the concavo-convex shape Rc of 4.642 占 퐉 in the pressing face 30 is 4.55 占 퐉 (see Fig. 11), the lower limit of the radius of curvature of the chamfered portion 40, (See Fig. 10) of the average height Rc of the light-shielding film (not shown).

The concavo-convex shape of the pressing surface 30 is formed by, for example, sandblasting. When the concavo-convex shape of the pressing face 30 is formed by sand blasting, the average height Rc of the concave-convex shape of the pressing face 30 can be 0.45 탆. When the average height Rc of the concavo-convex shape of the pressing surface 30 is formed to exceed 0.45 탆, for example, the ceramic particles on the surface may be defected (dropped out). Therefore, the average height Rc of the concavo-convex shape on the pressing face 30 is more preferably 0.45 占 퐉 or less.

11 shows the evaluation results of the respective items of " crack " and " wire breaking failure " when the radius of curvature of the chamfered portion 40 is changed.

Here, the "crack" item is the same item as the "crack" item shown in FIG. The item " wire breaking failure " is an item indicating whether or not the Al wire W is appropriately divided after the second bonding process. In this " wire breaking failure " item, " o " is set when a failure of the Al wire W is not broken.

As shown in Fig. 11, in Comparative Examples 7 and 8, a crack occurred in the Al wire W after the first bonding process. In Comparative Example 9, after the second bonding step, the Al wire W broke badly.

On the other hand, in Examples 6 to 10, cracks were not generated in Al wire W after the first bonding process, and defective separation of Al wire W did not occur even after the second bonding process.

From this result, it is preferable that the radius of curvature of the chamfered portion 40 is 4.55 탆 or more and 20.3 탆 or less.

12 is a diagram showing the evaluation result of the " crack " item when the radius of curvature of the chamfered portion 40 is changed.

Evaluation was performed when the loop length of the bonding point of the first bonding (for example, the point on the lead electrode 100) and the bonding point of the secondary bonding (for example, the point on the pad electrode 200) was 3 mm or more. Here, the loop length is the length of the imaginary line connecting the center lines of both joints. As described above, in a package having a relatively long loop length or the like, the tension applied to the Al wire W in the loop forming process becomes large, and more cracks are likely to occur.

In Fig. 12, the "crack" item is the same item as the "crack" item shown in Fig. 10 and Fig.

As shown in Fig. 12, in Comparative Example (10), cracks were generated in the Al wire W after the first bonding process.

On the other hand, in Examples 11 to 13, cracks were not generated in the Al wire W after the first bonding process.

From this result, it is preferable that the radius of curvature of the chamfered portion 40 is not less than 12.8 탆 and not more than 20.3 탆.

This makes it possible to appropriately suppress the occurrence of cracks in the Al wire (W) even if the loop length of the bonding point of the first bonding, the secondary bonding, and the bonding point is 3 mm or more. In addition, it is possible to appropriately suppress the occurrence of defective division of the bonding wire after the second bonding process.

13 is a diagram showing the evaluation result of the " crack " item when the taper angle? 1 (see FIG. 3) of the tapered hole 20 is changed.

The angle? 2 of the boundary angle portion 50 between the insertion hole 11 and the tapered hole 20 is defined by the taper angle? 1. When the taper angle? 1 is relatively large, the angle? 2 of the boundary angle portion 50 becomes relatively small. Therefore, if the taper angle? 1 is excessively large, for example, cracks are generated in the portion of the Al wire W which has been in contact with the boundary corner portion 50. [

In Fig. 13, the item " crack " is an item indicating whether or not cracks have occurred in a portion of the Al wire W after the first bonding process which was in contact with the boundary leg portion 50. [ In this " crack " item, the case where no crack occurred is indicated as "? &Quot;.

As shown in Fig. 13, in Comparative Examples 11 and 12, since the taper angle [theta] 1 of the tapered hole 20 was too large, a crack occurred in the Al wire W after the first bonding process.

On the other hand, in Examples 14 and 15, cracks were not generated in the Al wire W after the first bonding process.

From this result, it is preferable that the taper angle [theta] 1 of the tapered hole 20 is 100 [deg.] Or less.

As a result, occurrence of cracks in the Al wire W can be suitably suppressed.

The taper angle? 1 of the tapered hole 20 is preferably 0 ° or more. When the radius of curvature of the chamfered portion 40 is set to a predetermined value (for example, 4.55 占 퐉 or more, 20.3 占 퐉 or less, or 12.8 占 퐉 or more and 20.3 占 퐉 or less), when the taper angle? 1 of the tapered hole 20 is 0 ° or 0 °, cracks are prevented from being generated in the portion of the Al wire W that has been in contact with the chamfered portion 40.

Energy is generated for bonding the Al wire W and the lead electrode 100 to the interface between the Al wire W and the lead electrode 100 at the time of bonding (hereinafter simply referred to as "interface"). The energy distribution affects the bond strength.

14 is a schematic perspective view showing an example of a simulation result at the time of bonding.

15 is a schematic plan view showing an example of the simulation result of the energy distribution at the time of bonding.

16 is a diagram showing the evaluation results of the " bonding strength " item when the wire diameter Dw and the pressing face outer diameter Dp are changed.

Fig. 14 is a view showing the joining portion obliquely from below. Fig. In the example shown in Fig. 14, the boundary surface has an approximately elliptical shape. In Fig. 14, the energy distribution obtained by the simulation is contour-displayed on the boundary surface.

For example, the energy distribution is changed by changing the ratio Rd (= Dp / Dw) of the pressing surface outer diameter Dp (see Fig. 3) and the wire diameter Dw (see Figs. 7 and 8). 3, the compression surface outer diameter Dp is an imaginary circle (Cr) generated by intersecting an extending surface of the outer peripheral surface of the bottle neck portion 14 and a plane including the end portion of the tapered hole 20, .

Fig. 15 (a) shows a simulation result when the ratio Rd between the wire diameter Dw and the pressing surface outer diameter Dp is less than six times. Fig. 15 (b) shows a simulation result when the ratio Rd between the wire diameter Dw and the pressing surface outer diameter Dp is 6 or more times.

Fig. 15 (a) and Fig. 15 (b) show half of the energy distribution.

The item " stitch bonding " in Fig. 16 indicates whether or not sufficient bonding strength is obtained in the stitch portion S shown in Fig. 8 after the second bonding process. In the " stitch bonding " item, a case where sufficient bonding strength is obtained is indicated by "? &Quot;. The average height Rc of the concavo-convex shape of the specimen used in the present evaluation on the pressing surface 30 is not less than 0.20 占 퐉 and not more than 0.23 占 퐉.

As shown in Fig. 13, in Comparative Examples 13 and 15 in which the ratio (Rd) is relatively large, a predetermined bonding strength can not be obtained. This is because the area of the pressing surface 30 is excessively large with respect to the wire diameter Dw and the amount of energy generated per unit area generated at the interface is small. In this case, a predetermined bonding strength can not be obtained, and the Al wire W may be peeled from the lead electrode 100 at the interface.

On the other hand, also in Comparative Example 14 in which the ratio Rd is relatively small, a predetermined bonding strength can not be obtained. This is because the area of the pressing surface 30 is too small with respect to the wire diameter Dw, and a sufficient joining area can not be obtained.

On the other hand, in Examples 16 to 19, the ratio (Rd) was 4.0 times or more and 5.7 times or less. In Examples 16 to 19, desired bonding strength is obtained.

From the above results, it is preferable that the ratio Rd is 4.0 times or more and 5.7 times or less.

As a result, a desired bonding strength is obtained.

(Manufacturing method)

Next, an example of a manufacturing method of the capillary 1 according to the present embodiment will be described with reference to Fig. 17 is a flow chart illustrating a part of the manufacturing method of the capillary 1. 17 shows the order of forming the chamfered portions 40 in the manufacturing method of the capillary 1 and the order of forming the concave and convex shapes on the pressing surface 30 and the chamfered portion 40. [

As shown in Fig. 17, the chamfered portion 40 is first formed at the border portion between the pressing surface 30 and the tapered hole 20 by R chamfering (step S101). The R chamfering is performed, for example, by brush polishing. As the conditions of the brush polishing, there are, for example, a polishing pressure and a polishing time. By optimizing these conditions, the chamfered portion 40 having a desired radius of curvature can be formed.

Subsequently, the pressing surface 30 and the chamfered portion 40 are sandblasted to form a concave-convex shape on the surface of the pressing face 30 and the chamfered portion 40 (step S102).

The degree of sharpness of the convex portion 41 in the concavo-convex shape of the chamfered portion 40 is determined by the sharpness of the convex portion 31 in the convexo-concave shape of the pressing face 30, (Step S103). Thereby, the chamfered portion 40 is provided between the pressing surface 30 and the tapered hole 20 and the capillary (not shown) having a fine concavo-convex shape on the surface of the pressing surface 30 and the chamfered portion 40 1).

The order of the above-described manufacturing method is an example, and the chamfered portion 40 and the concavo-convex shape may be formed by other procedures. For example, after sandblasting is performed in step S102, both of the pressing surface 30 and the chamfered portion 40 may be subjected to brush polishing before brushing only the chamfered portion 40 in Step S103. The surface area of the front end portions of the convex portions 31 and 41 is larger than that of the bottom portion of the concave portions 32 and 42 on the surface of the pressing face 30 and the chamfered portion 40. In other words, It is possible to reliably form a concavo-convex shape in which the degree of sharpness of the portions 31 and 41 is smaller than the degree of sharpness of the concave portions 32 and 42. [ The brush polishing of the pressing surface 30 and the chamfered portion 40 may be performed after Step S103.

(Modified example)

Although the above-described embodiment has been described using a so-called bottle neck type bonding capillary, the bonding capillary disclosed herein does not necessarily need to be a bottle neck type bonding capillary. For example, a normal type bonding capillary not having a bottle neck portion, that is, a tip portion of which is not cut narrowly may be used.

In the above-described embodiment, the example in which the concavo-convex shape is formed on the pressing face and the chamfered portion has been described. However, the pressing face does not necessarily need to have the concave-convex shape. Further, the chamfered portion and the tapered hole may be provided with concave and convex shapes.

In the above-described embodiment, the pad electrode of the semiconductor chip and the lead electrode of the lead frame are electrically connected to each other. However, the bonding capillary disclosed in the present application is not limited to the case of bonding the bonding wire to other objects Lt; / RTI >

Additional advantages or modifications may readily be derived by those skilled in the art. Therefore, the broader embodiments of the present invention are represented as described above, and the present invention is not limited to the above-described specific details and representative embodiments. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

W: Al wire T: Tail part
S: stitch part Cr: virtual circle
Dp: Compression surface outer diameter Dw: Wire diameter
1: Bonding capillary 11: Insertion hole
12: Cylinder part 13: Conical part
14: Bottle neck part 20: Tapered hole
30: compression face 40: chamfer
50: border part 100: lead electrode
200: pad electrode

Claims (12)

A pressing surface for pressing the bonding wire,
An insertion hole through which the bonding wire is inserted,
A tapered hole connecting the insertion hole and the pressing surface and widening toward the pressing surface,
And a chamfered portion formed between the tapered hole and the pressing surface,
The chamfered portion may include:
And the degree of sharpness of the convex portion in the convexo-concave shape is smaller than the degree of sharpness of the concave portion in the convexo-concave shape. The method according to claim 1,
The concavo-convex shape of the chamfered portion is,
Wherein the degree of distortion is not more than -0.164 and the average height is not less than 0.035 占 퐉 and not more than 0.092 占 퐉. 3. The method according to claim 1 or 2,
The pressing surface
And the degree of sharpness of the convex portion in the concavo-convex shape of the pressing surface is larger than the degree of sharpness of the convex portion in the concavo-convex shape of the chamfered portion. The method of claim 3,
The convexo-concave shape of the pressing surface
And an average height of 0.113 mu m or more. 3. The method according to claim 1 or 2,
The chamfered portion may include:
The curved surface continuing smoothly to the tapered hole and the pressing surface, and the curvature radius of the curved surface is not less than 4.55 mu m and not more than 20.30 mu m. 3. The method according to claim 1 or 2,
The chamfered portion may include:
The curved surface continuing smoothly to the tapered hole and the pressing surface, and the radius of curvature of the curved surface is not less than 12.8 탆 and not more than 20.30 탆. 3. The method according to claim 1 or 2,
Wherein the tapered hole has a taper angle of 100 DEG or less. 3. The method according to claim 1 or 2,
And the outer diameter of the pressing surface is 4.0 times or more and 5.7 times or less of the wire diameter of the bonding wire. 3. The method according to claim 1 or 2,
The pressing surface
And the degree of sharpness of the convex portion in the concavo-convex shape of the pressing face is larger than the degree of sharpness of the convex portion in the concavo-convex shape of the chamfered portion,
The convexo-concave shape of the pressing surface
An average height of 0.113 mu m or more,
The chamfered portion may include:
The curved surface continuing smoothly to the tapered hole and the pressing surface, and the curvature radius of the curved surface is not less than 4.55 mu m and not more than 20.30 mu m. 3. The method according to claim 1 or 2,
The pressing surface
And the degree of sharpness of the convex portion in the concavo-convex shape of the pressing face is larger than the degree of sharpness of the convex portion in the concavo-convex shape of the chamfered portion,
The convexo-concave shape of the pressing surface
An average height of 0.113 mu m or more,
The chamfered portion may include:
The curved surface continuing smoothly to the tapered hole and the pressing surface, and the radius of curvature of the curved surface is not less than 12.8 탆 and not more than 20.30 탆. 10. The method of claim 9,
The taper angle of the tapered hole is 100 DEG or less,
And the outer diameter of the pressing surface is 4.0 times or more and 5.7 times or less of the wire diameter of the bonding wire. 11. The method of claim 10,
The taper angle of the tapered hole is 100 DEG or less,
And the outer diameter of the pressing surface is 4.0 times or more and 5.7 times or less of the wire diameter of the bonding wire.

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