JPS6179238A - Bonding tool and wire bonding device provided with that bonding tool as well as wire bonding method using that bonding tool and semiconductor device obtained by using that bonding tool - Google Patents

Abstract

PURPOSE:To reduce the bonding area by arranging a slit at the front of a capillary as a bonding tool. CONSTITUTION:A slit 14 is arranged in a longitudinal direction of a capillary 12 and it shapes as if it divides the capillary in the longitudinal direction. Through this capillary 12, a wire 15 is inserted. Also, the capillary 12 is supported by a clamper 16. A driving part 34 is composed of, e.g., piezoelectric element. When no voltage is applied to the driving part 34, the clamper 16 is open and the degree of closing of the clamper 16 can be changed by intensity of the voltage applied to the driving part 34. By such constitution, there is no space between an internal diameter of a front end of the capillary 12 and a diameter of the wire 15 so that the area which the front end of capillary 12 pushes the ball formed at the front end of the wire 15 enhances and the pressure-contact property is improved. Accordingly, if the ball is formed to be small, the wire bonding with the desired strength of pressure contact can be done.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to wire bonding technology, and particularly to a technology that is effective when used for wire bonding in a micro area.

[Background Art] The nail head bonding method is the most standard bonding method using gold wire in integrated circuits.

The sample is heated to about 300° C., and a gold wire with a ball-shaped tip is pressed against the aluminum electrode portion for a certain period of time, and bonding is performed by mutual diffusion of aluminum and gold.

Capillaries are made of glass or tungsten carbide and are available in various sizes depending on the wire diameter. When the gold wire is burnt out with a hydrogen flame, it melts and becomes spherical due to surface tension. The size of the gold ball is preferably about twice the diameter of the wire, and the adjustment of the size of the ball is determined by the size of the hydrogen flame and the speed at which the flame passes through the gold wire (
Integrated Circuit Handbook, published November 25, 1961,
Published by Maruzen Co., Ltd., p. 278).

The present inventor manufactured a semiconductor device using a wire bonding technique similar to the wire bonding technique described above.

By the way, as devices such as semiconductor integrated circuits become smaller and more highly integrated, the inventor of the present invention has developed a method for bonding parts of the object to be bonded, that is, aluminum electrode parts on the pellet (hereinafter referred to as pads) and the respective pads. I thought about making the lead smaller.

However, especially when bonding to the pad of a pellet, a ball with a diameter approximately twice the wire diameter is formed at the tip of the Au wire (hereinafter referred to as wire), and the ball is pressed against it for bonding. The ball collapses and the area where the wire is crimped (hereinafter referred to as the bonding area) becomes thicker. Therefore, even if the area of the pad is made small and many pads are provided on the pellet, the part where the ball is crushed and crimped by wire bonding (hereinafter referred to as the crimped part) may protrude from the pad or -
Minimize gaps such as contact with adjacent crimp parts,
The present invention was developed as a result of various studies to reduce the bonding area.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a slit is provided at the tip of the bonding tool and each capillary, and the inner diameter of the tip through hole of the capillary (hereinafter referred to as inner diameter) is made variable, so that the inner diameter of the tip of the capillary is
By forming a ball at the tip of the wire in a bulging state approximately equal to the wire diameter and performing wire bonding, the desired bonding strength can be obtained even with a ball diameter approximately 1.5 times the wire diameter.

In other words, pressing the ball at the tip of the capillary allows a desired area to be obtained and the bonding area to be small.

[Example 1] FIG. 31 is a side view of the tip of a capillary and the wire penetrating inside it.

FIG. 32 is a side view showing the wire being crimped onto the pad on the pellet.

FIG. 33 is a side view showing the state in which the capillary is raised after the wire is crimped to the pad on the pellet.

FIG. 34 is a side view showing a part of the object to be bonded after wire bonding.

In FIG. 31, 1 is the tip of the capillary (hereinafter referred to as capillary). 2 indicates the capillary tip. Reference numeral 3 denotes a wire, and a ball 4 is formed in a portion of the wire protruding from the tip 2 of the cavity by discharge from a discharge torch (not shown). 5 is a tab for placing pellets to be described later. 6 is a pellet provided with a pad 7 as a first bonding point. 8 is a lead as a second bonding point.

Here, it is assumed that the diameter of the wire 3 is Dl, the inner diameter of the capillary tip 2 is (D, +α), and the ball 4 is formed to have a diameter of 2D.

In FIG. 32, 9 is a crimping part. 10 is the neck.

In Fig. 34, number 11 indicates the crimping part at the second bonding point. The wire bonding procedure is as shown in Fig. 31, after forming the ball 4 at the tip of the wire 3, the capillary 1 is lowered. , as shown in FIG. 32, the ball 4 is pressed against the pad 7 as the first bonding point.

By the way, in order to make it easier for the wire 3 to pass through, the inner diameter of the tip of the capillary 1 can be made larger than the diameter (■) of the wire 3, and this larger dimension (hereinafter referred to as the gap between the capillary inner diameter and the wire ) is α, then when the capillary tip 2 of the capillary 1 presses the ball 4, the part of the ball 4 connected to the wire 3 () corresponds to the gap α between the capillary inner diameter of the ball 4 and the wire. In other words, in the end, the ball 4 deforms and is pressed by the capillary tip 2 by the dimension indicated by β in FIG. 33.Therefore, wire bonding A neck 10 having a diameter larger than the diameter of the wire 3 is formed between the rear wire 3 and the crimping part 9. Therefore, the present inventor has developed a method to eliminate the gap α between the inner diameter of the capillary tip 2 and the wire. For example, the area on which the capillary tip 2 presses against the ball 4 becomes larger, and the pressure bonding performance improves.
We thought that even if the outer circumference of the partial pressure thin part 9 was made small, bonding could be performed with the desired pressure bonding force. Figure 1 is a perspective view of a capillary, which is an embodiment of the present invention, seen from the tip direction. .

FIG. 2 is a diagram for explaining the relationship between the slit of the capillary and the inner diameter of the capillary tip.

FIG. 3 is a diagram showing a state in which the inner diameter of the capillary tip is reduced.

FIG. 4 is a side view of a wire bonding apparatus that is an embodiment of the present invention.

FIG. 5 is an enlarged perspective view of portion A in FIG. 4.

FIGS. 6 to 10 are diagrams for explaining wire bonding technology that is an embodiment of the present invention.

FIG. 11 is a side view showing a part of the pellet 9 lead frame after wire bonding.

FIG. 12 is a cross-sectional view taken along the line X-X@arrow in FIG. 11.

In FIG. 1, 12 indicates a capillary.

13 indicates the tip of the capillary. A slit 14 is provided in the longitudinal direction of the capillary 12 and is shaped to split the capillary 12 in the longitudinal direction. Assuming that the length of the slit 14 in the longitudinal direction is L, this L is
When a force is applied to the capillary 12 in the direction of the arrow in the figure (hereinafter referred to as a direction perpendicular to the slit forming direction), the length is such that the capillary 12 is easily elastically deformed, and the mechanical strength of the capillary 12 is not likely to decrease. It is preferable to make it long.

゛In Fig. 2, 15 is an Au wire (hereinafter referred to as wire)
It is. Here, the slit 14 formed in the capillary
Let the width of the capillary tip 13 be a, and the inner diameter of the capillary tip 13 and the wire 15
If b is the gap in the same direction as the width direction of the slit 14 (as shown in FIG. 2, gaps are formed on the left and right sides with respect to the center of the wire, respectively), In order to make the inner diameter of the capillary tip 13 substantially equal to the diameter of the wire 150, it is necessary to form the slit 14 so that the relationship a'=b+b holds.

In FIG. 3, 16 is a clamper, and the capillary 1
The clamper 16 is provided in the middle in the two longitudinal directions, and the inner diameter of the capillary tip 13 can be reduced by the clamping action.

In FIG. 4, 17 indicates a wire bonding device. A bonding head 18 is placed on the XY table 19 and is movable in the XY direction. This bonding head 18 has an internal vertical movement mechanism (not shown) for movement in the Z-axis direction, and a motor 20, which is a drive source for movement in the Z-axis direction, is connected and mounted on the top of the mechanism. ing. 21 is a vertical movement block;
It is connected to the bonding head 18 and can be moved up and down by the up and down movement mechanism.

An ultrasonic vibration source is connected to the front of the vertically moving block 21, and a bonding arm 22 that can generate ultrasonic vibrations is provided.
℃・ru is provided. A capillary 12, which is an embodiment of the present invention, is attached to the tip of this bonding arm 22, and a wire 15 passes through it. 23
is a clamper support body, which supports a clamper 16 for clamping the capillary 12. If the clamper 16 clamps the capillary 12 at a position close to the capillary tip 13, it can open and close the capillary tip 13 with a smaller force than when clamping it at a position farther from the capillary tip 13, but it will not interfere with bonding. It is preferable to install it at a position of approximately

Note that the capillary 12 is attached so that it can be clamped by the clamper 16 from a direction perpendicular to the direction in which the slit is formed.

24 is a discharge torch that can form a wire (not shown) coming out from the tip of the capillary 12 into a ball, and only when forming the ball, the tip of the discharge torch 24 is placed under the capillary 120. It is now possible to locate the 25 is a wire clamper, and the wire 1
5 can be clamped. 26 is a wire guide, which guides the wire 15 to the capillary 12.
This is to guide you inside. A support arm 27 protrudes from the top of the bonding head 18 and supports the spool 28 on which the wire 15 is wound.

This spool 28 sequentially connects the wire 15 to the capillary 12.
It is now possible to supply it within the country. 29 is a bonding stage, on the top of which a lead frame 31 to which pellets 30 are fixed is placed, and the bonding stage 29 is designed to be able to heat the lead frame 31 to a predetermined temperature. . 32 is a support stand, which is an embodiment of the wire bonding apparatus 1 of the present invention.
7 can be supported.

In FIG. 5, 33 is a fulcrum shaft, and the clamper 16
It can serve as a fulcrum for the clamping operation. 34 is
The clamper 16 is a driving part, and is composed of a piezoelectric element such as a piezoelectric ceramic. The degree of closure can be changed.

In Figures 6 to 10, 35 is a ball;
This is formed at the tip of the wire 15 by the discharge of the discharge torch 24. 36 is a tab constituting the lead frame 31, and a Pereno 30 is fixed onto this tab 36. A plurality of bands 37 are provided on the pellet 30 as first bonding points. Reference numeral 38 denotes a lead constituting the lead frame 31, and is provided corresponding to the pad 37. Reference numeral 39 denotes a crimp portion at the first bonding point (hereinafter referred to as the first crimp portion), and numeral 40 denotes a crimp portion at the second bonding point (hereinafter referred to as the second crimp portion).

In FIG. 12, reference numeral 41 indicates a streak-like portion of the first crimping portion 39, which is caused by the gap at the tip of the capillary during bonding.

The operation of the wire bonding technique having the above-mentioned configuration will be explained below.

A wire bonding device according to an embodiment of the present invention is characterized by having a clamp for clamping a capillary.

As shown in FIGS. 5 to 7, the inner diameter of the capillary tip 13 is reduced to approximately the same diameter as the wire 15 by the clamping action of the clamper 16 (hereinafter referred to as the capillary tip). In the closed state (・U), the ball 3 is formed at the tip of the wire 15 by the discharge of the discharge torch 24.
5 is formed. The bonding arm 22 descends while the capillary tip 13 remains closed, and the capillary tip 13 releases the ball 35 formed at the tip of the wire 15.
is pressed against a pad 37 serving as a first bonding point that has been heated in advance to about 100-odd degrees. Almost simultaneously with the pressing, the capillary 12 was heated at several KHz in the direction of the arrow in Fig. 7.
As shown in FIG. 8, the clamper 16 is released and the inner diameter of the capillary tip 13 returns to its original state (hereinafter referred to as the open capillary tip).・In this state), capillary 1
2 rises. The capillary 12 then moves to the bonding point 38 as a second bonding point, and the capillary tip 1
3 presses the wire onto the lead 38. Here, the capillary 12 is subjected to ultrasonic imaging of several IQ (about z), and the wire 15 is crimped.
2 rises to the point where a little wire comes out from the tip,
The wire 1 is clamped by the wire clamper 25 shown in FIG.
5 is clamped, the capillary 12 and the wire clamper 25 are raised almost simultaneously, and the wire 15 is torn off as shown in FIG.

Thereafter, the above-described operations are repeated to wire-bond the plurality of pads of the bullet and the corresponding plurality of leads.

According to the wire bonding technology described above, the ball formed at the tip of the wire can be held by the tip of the capillary without creating a gap in the inner diameter of the capillary tip relative to the diameter of the wire, so the ball can be pressed by the tip of the capillary. The area increases, the crimping properties improve, and the ball to be formed is made smaller accordingly, reducing the maximum outer diameter of the first crimping part (
Even if the outer diameter of the first crimping part (hereinafter referred to as the outer diameter of the first crimping part) is made smaller, wire bonding can be performed with the desired pressure.

In this way, by making the outer diameter of the first crimping part smaller, the size of the band as the first bonding point can also be made smaller.
It becomes possible to

In addition, since the size of the pad can be reduced, the hesing of the part of the pellet where the band is provided is improved, which allows the pellet to be made smaller and, as a result, it is possible to make the semiconductor device smaller. It becomes possible.

Since the spacing of the portion of the pellet where the pad is provided is improved, a new pad can be provided, and the increase in the external size of the pellet can be reduced, making it possible to cope with high integration.

By the way, according to the wire bonding technology mentioned above,
The wires are bonded with the characteristics shown below.

In other words, the ball formed at the tip of the wire can be held down by the capillary tip without creating a gap in the inner diameter of the capillary tip relative to the wire diameter.
As shown in the figure, a neck as shown at 10 in FIG. 34 does not occur between the first crimping part 39 and the wire 15.

In addition, a slit is formed in the capillary to
Even if the tip of the capillary is closed and wire bonded, as shown in FIG. 12, a tooth-shaped portion 41 is generated at the first crimping portion due to the gap at the tip of the gearillary.

In addition, the present inventor conducted wire bonding experiments based on the above-mentioned embodiment. As a result, even when wire bonding was performed with a ball having a diameter of about 1.5 times the wire diameter, the In one crimping part, the desired crimping force could be obtained with a crimping part diameter approximately 2.3 times the wire diameter.

By the way, in this embodiment, the clamper that clamps the capillary is opened and closed by a piezoelectric element, but the clamper may also be opened and closed by rotation of a cam. In that case,
The cost is lower than that using piezoelectric elements. There are other possibilities, including the shape of the clamper, such as opening and closing the clamper using a solenoid.

Further, as shown in FIG. 13, the inner diameter is tapered 4. Lever 43 with attached ring 42
is provided, and the vertical movement of the lever 43 or the capillary 1
The capillary tip 13 may be opened and closed by the vertical movement of the capillary 2, and in that case, the mechanism is simpler than that using a clamper.

In this embodiment, the capillary is provided with a slit that divides the tip of the capillary into two, but the capillary has a slit that divides the tip of the capillary into two or more, for example, as shown in FIG. A slit may be provided, and compared to a capillary whose tip is divided into two, the capillary is more easily deformed, and the capillary tip has a larger area for clamping the wire, resulting in better clamping performance.

Further, in order to make the capillary easier to deform, the capillary may be processed as shown in FIG. 15 or 16. That is, in FIG. 15, if the end of the slit 14 on the side opposite to the capillary tip 13 in the portion of the capillary 12 where the slit 14 is formed is defined as the slit end 44, the slit end 44 of the capillary 12
The capillary 12 becomes easier to deform by making the surrounding area thinner over the outer periphery of the capillary. As shown in FIG. 16, by making the portion of the capillary 12, which is substantially perpendicular to the longitudinal direction of the slit, thin in plan view over the longitudinal direction from the vicinity of the slit end 44 to the vicinity where the clamper 16 is disposed. Also, the capillary becomes easily deformed. Therefore, the capillary can be deformed with a smaller force than when deforming a capillary that does not have a thin portion. Furthermore, when attaching the capillary to the bonding arm of the wire bonding machine,
If the thin portion is used as an index, positioning with respect to the clamper can be easily performed.

By the way, in this example, before forming a ball on the wire tip, the capillary is deformed to reduce the inner diameter of the capillary tip, but at the time of bonding the ball, the inner diameter of the capillary tip becomes equal to the wire diameter. It is sufficient if they are approximately equal. In this example, the capillary is moved from the first bonding point to the second bonding point with the capillary not deformed, but the capillary is deformed and the inside diameter of the capillary tip is approximately equal to the wire diameter. It is also conceivable to perform the capillary movement described above. However, in that case, when the capillary is moved, the wire may rub inside the capillary and the wire may break, so it is preferable to move the capillary while the capillary is not deformed, as in this embodiment.

In addition, in this example, bonding is performed with the capillary not deformed during lead-side bonding, but the lead-side bonding is performed with the capillary deformed and the capillary tip inner diameter and wire diameter being approximately the same. In that case, it is considered that the ultrasonic vibration is better transmitted to the wire and the crimping properties are improved.

If part or all of the capillary is constructed from a piezoelectric element such as a piezoelectric ceramic, the capillary tip can be opened and closed by applying voltage to the capillary itself, without the need for a clamper to open and close the capillary tip.

[Embodiment 2] FIG. 17 is a perspective view showing a capillary as another embodiment of the present invention.

FIG. 18 is a diagram for explaining the relationship between the slit of the capillary and the inner diameter of the tip of the capillary.

FIG. 19 is a diagram showing a state in which the inner diameter of the capillary tip is reduced (closed).

FIG. 20 is a side view showing a wire bonding apparatus as another embodiment of the present invention.

FIG. 21 is an enlarged perspective view of portion B in FIG. 20.

FIGS. 22 to 27 are diagrams for explaining wire bonding technology according to another embodiment of the present invention.

FIG. 28 is a partially enlarged view of FIG. 27.

FIG. 29 is a side view as viewed from the y@arrow in FIG. 28.

FIG. 30 is a side view taken along the z-2 line in FIG. 29.

In FIG. 17, 45 indicates a capillary.

46 indicates the capillary tip. A slit 47 is provided in the longitudinal direction of the capillary 45 and is shaped to split the capillary 45 in the longitudinal direction. Assuming that the length of the slit 47 in the longitudinal direction is L, this L is
When a force is applied to the capillary 45 in the direction of the arrow in the figure (hereinafter referred to as the slit forming direction), the capillary 45 easily deforms elastically and the mechanical strength of the capillary 45 decreases. It is preferable to make the length so that it is difficult.

In FIG. 18, 48 is an All wire (hereinafter referred to as wire). Here, the slit 4 formed in the gear pillar
The width of 7 is a, and the inner diameter of the capillary tip 46 and the wire 4
8 in the same direction as the width direction of the slit 47 (
As shown in Fig. 18, gaps are formed on the left and right sides with respect to the center of the wire, and if each gap is b, then the slit 47 is formed so that a) b -) -1). When the capillary 45 is deformed to reduce the inner diameter of the capillary tip 46, the wire 48 can be clamped at the capillary tip 46.

In FIG. 19, a clamper 49 is provided in the longitudinal direction of the capillary 45, and the clamping action of the clamper 49 deforms the capillary 45, and the capillary tip 46 clamps the wire 48.

In FIG. 20, 50 indicates a wire bonding device. A bonding head 51 is placed on the XY table 52 and is movable in the XY direction. This bonding head 51 has an internal vertical movement mechanism (not shown) for movement in the Z-axis direction, and a motor 53 that is a drive source for movement in the Z@ direction is connected and placed on the top of the mechanism. ing. Reference numeral 54 denotes a vertical movement block, which is connected to the bonding head 51 and can be moved up and down by the vertical movement mechanism.

An ultrasonic vibration source is connected to the vertical movement block 54, and a honding arm 55 that can generate ultrasonic vibrations is connected to the vertical movement block 54.
is provided. The above-described capillary 45 is attached to the tip of this bonding arm 55, and the wire 48 is passed through it. Reference numeral 56 denotes a clamper support, which supports a clamp (49) for clamping the capillary 45. When the clamper 49 clamps the capillary 45 at a position close to the capillary tip 46, it will move away from the capillary tip 46. Although it is possible to open and close the capillary tip 46 with a smaller force than when the capillary tip 46 is clamped at a fixed position, it is preferably installed at a position that does not interfere with bonding.

Note that the capillary 45 is attached so that it can be clamped by a clamper 49 from a direction perpendicular to the direction in which the slit is formed. 57 is a wire guide for guiding the wire 48 into the capillary 45. A support arm 58 protrudes from the top of the bonding head 51 and supports a spool 59 around which the wire 48 is wound. This spool 59 is capable of sequentially supplying the wire 48 into the capillary 45. Reference numeral 60 denotes a bonding stage, on which a lead frame 62 to which a pellet 61 is fixed is placed, and the bonding stage 60 is capable of heating the lead frame 62 to a predetermined temperature. Reference numeral 63 denotes a support stand that can support the wire bonding device 50 having the above-described configuration.

In FIG. 21, 64 is a fulcrum shaft, and the clamper 4
This can serve as a fulcrum for the clamping operation of step 9. Reference numeral 65 denotes a drive unit, which is composed of a piezoelectric element such as a piezoelectric ceramic. If no voltage is applied to the drive unit 65, the clamper 49 is in an open state, and the magnitude of the voltage applied to the drive unit 65 is This makes it possible to change the degree to which the clamper 49 closes.

In FIGS. 22 to 27, 66 is a tab constituting the lead frame 62, and the pellet 61 is fixed onto this tab 66.

A plurality of pads 67 are provided on the pad 61 as a first bonding point.

Reference numeral 68 denotes a band forming the lead frame 62, and is provided corresponding to the band 67. Reference numeral 69 denotes a crimp portion at the first bonding point (hereinafter referred to as the first crimp portion), and numeral 70 denotes a crimp portion at the second bonding point (hereinafter referred to as the second crimp portion).

In FIG. 28 or 29, the diameter of the wire 48 is assumed to be the diameter of the wire 48, and the wire 4 in the same direction as the arrow Y in the figure
8 and the diameter of the wire near the joint with the first crimping part 69. The diameter of the wire in the vicinity of the joint between the wire 48 and the first crimp portion 69 in the direction perpendicular to the direction of the arrow Y is Da. The wire 48 is deformed by the clamping action of the capillary tip 46, and the wire 48 is deformed by the clamping action of the capillary tip 46.
8 extends in the slit forming direction of the capillary, the wire diameter in that direction is reduced, and the wire diameter is reduced in the direction orthogonal to the slit forming direction. The relationship between them is Dt>Dt>Da.

Furthermore, the wire is scratched due to being clamped by the tip of the capillary.

In FIG. 30, reference numeral 71 indicates a tooth-shaped portion of the first crimping portion 69, which is created by a gap at the tip of the capillary during bonding.

The operation of the wire bonding technique having the above-mentioned configuration will be explained below.

According to this embodiment, the wire bonding apparatus has the 20th
As shown in the figure, the present invention is characterized by having a clamper for clamping the capillary without requiring a discharge torch and a clamper for cutting the wire.

As shown in FIGS. 21 to 23, when a predetermined amount of wire 48 has been inserted from the capillary tip 46,
The clamping action of the clamper 49 closes the capillary tip 46, and the wire 48 is clamped at the capillary tip 46. With the wire 48 still clamped by the capillary tip 46, the bonding arm 55 descends, and the capillary tip 46 causes the tip of the wire 48 to touch a pad 67 as a first bonding point that has been preheated to about 100 degrees Celsius. Being pushed. Almost at the same time as the pressing, a few kilometres of pressure was applied to the capillary 45 in the direction of the arrow in FIG.
Two or so ultrasonic images are applied, and the tip of the wire 48 is crimped. At this time, although the tip of the wire 48 is crimped, the maximum outer diameter of the first crimping part 69 (hereinafter referred to as the first crimping part (the outer diameter of the part) becomes smaller. Next, the capillary tip 46 opens and the bonding arm 55 rises with the gearillary tip releasing the wire clamp. When the capillary 45 has risen as specified, the wire 48 is lifted as shown in FIG.
is clamped by capillary tip 46. Thereafter, as shown in FIG. 25, the capillary 45 is connected to the second
Move to the glue lead 68 as a bonding point and press the wire 48 onto the lead 68 by the capillary tip 46. Here, ultrasonic vibration of about several KHz is applied to the capillary 45, and the wire 48 is crimped. The capillary tip 46 is opened, the wire 48 is unclamped,
The capillary 45 rises to such an extent that the wire 48 slightly protrudes from its tip, the capillary tip 46 closes and the wire 48 is clamped, and then the capillary 45 rises and the second
As shown in Figure 7, the wire 48 is torn off.

Repeat the above operation to remove multiple pads on the beret and
A plurality of corresponding leads are wire-bonded.

According to the wire bonding technology described above, the wire does not come out of the capillary even if a ball is not formed at the tip of the wire, and since the wire is clamped at the tip of the capillary, the tip of the wire can be attached to the tip of the capillary. Can be pressed against the bonding point. Therefore, especially in the first crimping part, bonding can be performed with a smaller maximum outer diameter of the crimping part than in a case where a ball is formed at the tip of the wire and the ball is pressed against the wire. By making the outer diameter of the first crimping part smaller, it is also possible to make the size of the pad as the first bonding point smaller.

In addition, since the size of the pad can be reduced, the spacing of the part of the pellet where the band is provided is improved, which allows the pellet to be made smaller, and as a result, the size of the semiconductor device can also be made smaller. Obtainable.

Since the spacing of the portion of the pellet where the band is provided is improved, a new band can be provided, and the increase in the external size of the pellet can be reduced, making it possible to cope with high integration.

By the way, according to the wire bonding technology mentioned above,
The wires are bonded with the characteristics shown below.

That is, as shown in FIGS. 28 to 30,
A neck as shown by 10 in FIG. 34 does not occur between the first crimping part 69 and the wire 48, and the first crimping part 69
The wire 48 near the joint with the wire 48 is deformed into an elliptical cross section.

Also, since a slit is formed in the capillary, even if the capillary tip is closed and wire bonded, the third
As shown in FIG. 0, in the first crimping portion, a slit-shaped portion 71 is generated due to the gap at the tip of the capillary.

The inventor also conducted a wire bonding experiment based on the above-described embodiment. As a result, it was revealed that by reducing the amount of wire coming out from the tip of the capillary, the wire becomes less likely to break at the pad serving as the first bonding point, and bonding can be performed with a crimp diameter that is the same as the diameter of the wire. Ta.

By the way, in this embodiment, the clamper that clamps the capillary is opened and closed by a piezoelectric element, but the clamper may also be opened and closed by rotation of a cam. In that case,
The cost is lower than that using piezoelectric elements. In addition, the clamper is opened and closed using an electromagnet, etc.
Various shapes including the shape of the clamper can be considered.

Further, as shown in FIG. 13, a lever 43 is provided with a ring 42 whose inner diameter is tapered, and the capillary tip 13 is opened and closed by vertical movement of the lever 43 or vertical movement of the capillary 12. In that case, the mechanism is simpler than that using a clamper.

In this embodiment, the capillary is provided with a slit that divides the tip of the capillary into two, but the capillary has a slit that divides the tip of the capillary into two or more, for example, as shown in FIG. A slit may be provided, and the capillary is more easily deformed than a capillary whose tip is divided into two.

Further, in order to make the capillary easier to deform, the capillary may be processed as shown in FIG. 15 or 16. That is, in FIG. 15, if the end of the slit 14 on the side opposite to the capillary tip 13 in the portion of the capillary 12 where the slit 14 is formed is defined as the slit end 44, the slit end 44 of the capillary 12
The capillary 12 becomes easier to deform by making the surrounding area thinner over the outer periphery of the capillary. As shown in FIG. 16, the portion of the capillary 12 that is substantially perpendicular to the longitudinal direction of the slit is made thin in plan view over the longitudinal direction from the vicinity of the slit end 44 to the vicinity where the clamper 16 is arranged. Also, the capillary becomes easily deformed. Therefore, the capillary can be deformed with a smaller force than when deforming a capillary that does not have a thin portion. Furthermore, when attaching the capillary to the bonding arm of the wire bonding machine,
If the thin portion is used as an index, positioning with respect to the clamper can be easily performed.

If part or all of the capillary is constituted by a piezoelectric element such as a piezoelectric ceramic, the capillary tip can be opened and closed by applying voltage to the capillary itself, even without a clamper for opening and closing the capillary tip.

Further, in this embodiment, a discharge torch for forming a ball at the tip of the wire is not provided, but even if this discharge torch is provided and a ball is not formed at the tip of the wire, the discharge time can be shortened. It is also possible to round the tip of the wire and then bond it to the first bonding point, which makes crimping easier and improves the crimping force compared to the case where the tip of the wire is not rounded.

In this example, after bonding to the pad as the first bonding point, the capillary is raised to a predetermined height with the tip of the capillary open, and with the wire clamped at the tip of the capillary, the capillary is bonded to the pad as the second bonding point. I moved to the lead and bonded, but
This is to ensure that the wire formed between the pad and the lead does not become loose during bonding. If that is not necessary,
After bonding the pad, the capillary tip may be moved to a second bonding point in an open state and bonded. In this case, the number of times the capillary tip is opened and closed can be reduced compared to the method described above. , wire bonding efficiency increases.

If part or all of the capillary is constructed from a piezoelectric element such as a piezoelectric ceramic, the capillary tip can be opened and closed by applying voltage to the capillary itself, even without a clamper for opening and closing the capillary tip. Then,
The wire bonding device does not require a clamper to open and close the capillary tip.

In addition, in this embodiment t, a slit is provided in the capillary and the wire is clamped at the tip of the capillary, but a through hole is provided at the tip of the capillary in a direction perpendicular to the longitudinal direction of the capillary, and the wire is slid inside the through hole. Wire bonding can also be performed by clamping the wire with a slide lever capable of clamping the wire in the capillary and using the same bonding method as in the embodiment described above. In this case, there is no need to elastically deform the capillary, so the life of the capillary is extended.

In Fig. 13, the tip of the capillary is opened and closed by vertical movement of a ring having a tapered opening. The tip of the capillary may be opened and closed by sliding a slide lever or moving the capillary up and down.

By the way, in Examples 1 and 2, the wire is pressed against the preheated object to be bonded, and further ultrasonic vibration is applied to the wire, but in the present invention, the wire is crimped by pressing the wire against the preheated object to be bonded. It can also be applied to a device in which a wire is pressed against a bonded object to be crimped.

〔effect〕

1. By making the inner diameter of the capillary tip variable and performing wire bonding with the inner diameter of the capillary tip approximately equal to the wire diameter, the area on which the capillary tip presses against the ball formed at the wire tip becomes larger, improving crimping performance. Effects can be obtained.

2. The area on which the capillary tip presses against the ball formed at the wire tip becomes larger and the crimping property improves, so the ball formed at the wire tip is made smaller accordingly.
The effect is that the outer diameter of the crimping part can be made smaller.

3. The area on which the capillary tip presses against the ball formed at the wire tip becomes larger and the crimping performance improves, so the ball formed at the wire tip is made smaller and the outer diameter of the first crimping part is made smaller. Also, there is an effect that the desired pressure bonding force can be obtained.

4. By making the inner diameter of the tip of the capillary variable, the wire can be clamped at the tip of the capillary, so it is possible to reduce the possibility of the wire coming off from the capillary without forming a ball at the tip of the wire.

5. By being able to clamp the wire at the tip of the capillary, the wire itself can be pressed against the bonding point using the tip of the capillary, and compared to a method in which a ball is formed at the tip of the wire and the ball is pressed and crimped, the first crimping part is The effect is that wire bonding can be performed with a smaller outer diameter.

6. Wire bonding can be performed by reducing the outer diameter of the first crimping portion, resulting in the advantage of saving wire.

7. Since the outer diameter of the first crimping part can be made smaller, the band serving as the bonding point on the pellet can be made smaller, and the spacing near the band of the pellet can be improved, which has the effect of making the pellet smaller. can get.

8. By making the pellet smaller, the tab on which the pellet is placed can be made smaller, and ultimately the semiconductor device can be made smaller.

9. Since the outer diameter of the first crimping part can be made smaller, the pad as a bonding point on the pellet can be made smaller, which makes it possible to provide a new band on the pellet.
This has the effect of reducing the increase in the external size of the pellet and making it possible to cope with higher integration.

10. Since the outer diameter of the first crimping part can be made small, even if the bands on the pellet are close to each other, wire bonding can be performed with less contact between each crimping part and the adjacent band or crimping part. Effects can be obtained.

11. The wire can be clamped at the tip of the capillary and the wire itself can be pressed, so when bonding using Al wire, there is no need to form a ball on the tip of the A/wire, and it is possible to form a ball on the tip of the Al wire. No aluminum oxide formation on the ball surface. Therefore, it is possible to achieve the effect that Al wire can be bonded without deterioration of compression bondability due to aluminum oxide.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

In the above description, the invention made by the present inventor is mainly applied to the wire bonding technology in the manufacture of semiconductor devices, which is the background field of application, but the invention is not limited thereto.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a capillary according to an embodiment of the present invention viewed from the tip direction, FIG. 2 is a diagram for explaining the relationship between the slit of the capillary and the inner diameter of the capillary tip, and FIG. Capillary tip inner diameter? FIG. 4 is a side view of a wire bonding device according to an embodiment of the present invention; FIG. 5 is an enlarged perspective view of the vicinity of section A in FIG. 4; FIGS. 6 to 10 11 is a diagram for explaining the wire bonding technique that is an embodiment of the present invention, and FIG. 11 is a pellet after wire bonding. 12 is a side view showing a part of the lead frame; FIG. 12 is a sectional view taken along the line X-X in FIG. 11; FIG. 13 is a perspective view showing the capillary opening/closing mechanism;
Figure 15 is a perspective view showing another embodiment of the capillary of the present invention, Figure 15 or Figure 16 is a front view showing a capillary structure that facilitates opening and closing of the capillary tip, and Figure 17 is a perspective view showing another embodiment of the capillary of the present invention. FIG. 18 is a perspective view showing a capillary as another embodiment. FIG. 18 is a diagram for explaining the relationship between the capillary slit and the inner diameter of the capillary tip. FIG. 19 is a diagram showing a state in which the inner diameter of the capillary tip is reduced. 20 is a front view of a wire bonding device as another embodiment of the present invention, FIG. 21 is an enlarged perspective view of the vicinity of section B in FIG. 20, and FIGS. 22 to 27 28 is a partially enlarged view of FIG. 27; FIG. 29 is a side view as seen from the Y-line arrow in FIG. 28. Figure, 30th
The figures are a sectional view taken along the Z-Z line in Fig. 29, Fig. 31 is a side view of the tip of the capillary and the wire passing through it, and Fig. 32 is a cross-sectional view of the tip of the capillary and the wire passing through it. Figure 33 is a side view showing the state in which the wire is crimped; Figure 33 is a side view showing the capillary raised once after the wire is crimped to the band on the pellet; Figure 34 is the wire bonding completed. FIG. 3 is a side view showing a part of the object to be bonded. 1.12.45...capillary, 2,13.46...
・Capillary tip, 3, 15.48... Wire, 4° 35... Ball, 5, 36.66... Tab, 6, 3
0°61... Beret? , 37.67...Pad, 8°38.68...Lead, 9.11...Crimp part, 10...Neck, 14,47...Slit, 16
．． 49... Clamper, 17.50... Wire bonding device, 18.51... Bonding head, 1
9,52...X-Y table, 20.53...Motor, 21°54...Vertical movement block, 22.55...
・Bonding arm, 23.56... Clamper support, 24... Discharge torch, 25... Wire clamper, 26.57... Wire guide, 27.58... Support arm, 28° 59.・・Spool, 29.60・・
・Bonding stage, 31.62... Lead frame, 32.63... Support stand, 33.64... Fulcrum shaft, 34.65... Drive section, 39.69... First crimping section , 40.70... second crimp part, 41.71...
Chord-shaped portion, 42...Ring, 43...Lever, 44
...Slit end.

Claims (1)

[Scope of Claims] 1. A bonding tool having a through hole through which a wire is passed, the bonding tool being characterized in that a slit is formed in the direction of the wire passing through the tool. 2. As the slit, use one end of the bonding tool as the slit.
The bonding tool according to claim 1, characterized in that the bonding tool has a shape that is divided into a plurality of parts. 3. A wire bonding apparatus comprising a bonding tool, characterized in that the wire bonding apparatus is provided with a deformation mechanism for the bonding tool. 4. The wire bonding apparatus according to claim 3, wherein the deformation mechanism is a clamper that can be opened and closed by a piezoelectric element. 5. The wire bonding apparatus according to claim 3, wherein the deformation mechanism is a clamper that can be opened and closed by rotation of a cam. 6. The wire bonding apparatus according to claim 3, wherein the deformation mechanism is a clamper that can be opened and closed by a solenoid. 7. A wire bonding method in which a wire is passed through a bonding tool and wire bonded to an object to be bonded, the wire bonding method being characterized in that bonding is performed by changing the inner diameter of the bonding tool. 8. The wire bonding method according to claim 7, wherein the change in the inner diameter of the bonding tool is performed while the wire is held between the bonding tools. 9. A semiconductor device in which a terminal of an element and a lead for establishing conduction between the terminal and the outside are bonded with a wire, and the maximum diameter of the crimped portion of the wire bonded to the terminal is: 1 to 2.2 of the wire diameter
A semiconductor device characterized by being twice as large.