JP2002076049A - Wire bonding equipment and method for manufacturing electrical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire bonding equipment which can surely bond a ball formed on the tip of a wire to the electrode of a semiconductor chip. SOLUTION: The wire bonding equipment bonds a ball 7a formed on the tip of a wire 7 to the electrode of the semiconductor chip 9 by driving a bonding tool 4b in a driving target direction. The wire bonding equipment is equipped with a laser displacement gauge 14 which detects the height of the place where the wire of the semiconductor chip is to be bonded, and a control equipment 21 which bonds the ball to the electrode by controlling the drive in the drive target direction of the bonding tool according to the detection signal from the laser displacement gauge 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding apparatus for bonding a ball formed at the tip of a wire to a work such as a semiconductor chip or a lead frame, and a method of manufacturing an electric component.

[0002]

2. Description of the Related Art For example, when a semiconductor chip is mounted on a lead frame, wire bonding is performed to connect terminals formed on the semiconductor chip and terminals formed on the lead frame by wires.

[0003] To perform wire bonding, a wire bonding apparatus is used. As is well known, a wire bonding apparatus has a bonding head, and the bonding head is provided with an ultrasonic horn having a bonding tool at a tip. The ultrasonic horn is swingably driven by a drive source together with a swing arm.

A wire such as gold (Au) is passed through the capillary. A ball is formed at the tip of the wire, and the ball is pressed against the work while applying ultrasonic vibration to perform bonding.

In recent years, as circuit patterns formed on semiconductor chips have become finer, the diameter of balls formed on wires has also been reduced, for example, the diameter of balls has been reduced to about 40 μm.
It is about.

When bonding the ball to the work, first, the bonding tool is driven to swing to lower the capillary. The lowering position of the capillary is detected by a position sensor provided on the bonding head, and is controlled based on the detection of the position sensor. The position sensor detects a lowering position of the capillary from, for example, a swing angle of the swing arm.

In other words, conventionally, as shown by a driving curve M in FIG. 9A in which the vertical axis represents height and the horizontal axis represents time, the bonding tool 4b is moved at a high speed to a preset lowering position A first. Descended. Then switch to constant velocity descent, 1m
When the detection signal of the position sensor is further lowered while monitoring the detection signal of the position sensor at a cycle of about s, and the detection signal of the position sensor does not change any more, the semiconductor chip provided on the lead frame 8 as the work with the wire ball 7a When it is determined that the ball has contacted the electrode 9, the bonding tool is switched from the lowering operation to the pressing operation, and the ball 7 a is bonded to the semiconductor chip 9.

[0008]

However, if the position sensor detects the position of the bonding tool at predetermined intervals, it is difficult to detect the moment when the ball 7a comes into contact with the semiconductor chip 9. When the bonding tool 4b further descends after the contact, it is determined that the ball 7a has contacted the semiconductor chip 9.

As shown by a load curve N in FIG. 9B, when the ball 7a collides with the semiconductor chip 9, an impact load C is generated, and the ball 7a is crushed by the impact load C. Even if 4b shifts from the lowering operation to the pressing operation D, a crushing margin of the ball 7a cannot be secured, leading to a bonding failure. In the case of a fine circuit pattern, the ball 7a that has been excessively crushed is Contact with an electrode other than the predetermined electrode may cause a contact failure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wire bonding apparatus and a method of manufacturing an electric component, wherein a ball formed on a wire collides with a workpiece and can be bonded without being crushed too much.

[0011]

According to a first aspect of the present invention, there is provided a wire bonding apparatus for driving a bonding tool in a drive target direction to bond a ball formed at the tip of a wire to a work. Detecting means for detecting the height of a portion to be bonded in a non-contact manner, and controlling the driving of the bonding tool in a drive target direction based on a detection signal from the detecting means to bond the ball to the workpiece; And a wire bonding apparatus.

According to a second aspect of the present invention, the control means calculates a drive target position of the bonding tool from a height position of the work detected by the detection means, and the control means calculates a target position of the bonding tool based on a calculation result of the calculation part. 2. A drive unit for controlling the driving of the bonding tool in a drive target direction immediately before or until the ball comes into contact with the workpiece, and then pressing the ball against the workpiece. Wire bonding equipment.

According to a third aspect of the present invention, there is provided a method of manufacturing an electric component in which a bonding tool is driven in a drive target direction to bond a ball formed at the tip of a wire to a work. And a bonding step of controlling the driving of the bonding tool in the drive target direction based on the detection result of the detection step to bond the ball to the workpiece. A method for manufacturing an electrical component.

According to a fourth aspect of the present invention, in the bonding step, a driving target step of driving the bonding tool immediately before or until the ball contacts the work, and a pressurizing step of pressing the ball against the work. 4. The wire bonding method according to claim 3, further comprising the steps of:

According to a fifth aspect of the present invention, there is provided a method of manufacturing an electric component according to the third or fourth aspect, wherein the detecting step is performed on the work, and then the bonding step is performed.

According to a sixth aspect of the present invention, there is provided a method of manufacturing an electric component according to the third or fourth aspect, wherein the detecting step and the bonding step are performed independently for different works.

According to a seventh aspect of the present invention, there is provided a wire bonding apparatus for driving a bonding tool in a drive target direction to bond a ball formed at the tip of a wire to a workpiece, wherein the driving unit drives the bonding tool in the drive target direction. Acceleration detection means for driving the bonding tool in the drive target direction by the driving unit to detect a change in acceleration of the bonding tool when the ball comes into contact with the workpiece; and acceleration detected by the acceleration detection means. Control means for controlling the driving of the bonding tool in the drive target direction based on the change of the wire bonding apparatus.

According to an eighth aspect of the present invention, there is provided a method of manufacturing an electric component for driving a bonding tool in a drive target direction and bonding a ball formed at the tip of a wire to a workpiece, wherein the bonding tool is driven in the drive target direction. A driving step of driving the bonding tool in a drive target direction and detecting a change in the acceleration of the bonding tool when the ball comes into contact with the workpiece, based on the detected change in the acceleration of the bonding tool. And a control step of controlling drive in the drive target direction.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention, and FIG. 1 shows a schematic configuration of a bonding apparatus.
This bonding apparatus includes a bonding head 1. The bonding head 1 is provided on an XY table 2 and can be driven and positioned in the XY directions by a control device 21 described later.

The bonding head 1 has a swing arm 3
Is provided. The swing arm 3 is provided with an ultrasonic horn 4a and a clamp arm 6 having a clamper 5 at the tip. The swing arm 3 swings the ultrasonic horn 4a and the clamp arm 6 at a predetermined timing.

A bonding tool 4b is provided at the tip of the ultrasonic horn 4a.
A wire 7 such as gold held by the clamper 5 is passed through b.

A ball 7a is formed at the tip of the wire 7 protruding from the lower end of the bonding tool 4b by a torch (not shown) or the like. The ball 7a is an electrode of a semiconductor chip 9 provided on a lead frame 8 as a work.
(Not shown) as described later. The lead frame 8 is transported and positioned at a predetermined position by, for example, a frame feeder 10 as transport means.

The bonding head 1 is provided with a motor 11 for driving the swing arm 3 to swing.
The driving amount (rotation angle) of the swing arm 3 by the motor 11 is detected by the position sensor 12.

One end of a support arm 13 is attached to the bonding head 1. The tip of the support arm 13 extends above the bonding tool 4b,
At its tip, for example, a laser displacement meter 14 is provided. The laser displacement meter 14 detects the height position of the electrode of the semiconductor chip 9 by the laser light L. Further, an imaging camera 15 for imaging the semiconductor chip 9 is provided at a tip of the support arm 13.

The bonding device is connected to the control device 21.
The operation is controlled by this. The control device 21 includes a processing unit 22 and a control unit 23. The processing unit 22 includes an amplifier 24, an A / D converter 25, and a height calculation unit 26, and the control unit 23 includes a target position calculation unit 27, a comparison unit 28, a driving unit 29, and an image processing unit 30. I have.

The detection signal of the position sensor 12, that is, the height position (displacement amount) of the tip of the bonding tool 4b determined by the driving amount of the swing arm 3 is input to the comparison unit 28. An image signal of the semiconductor chip 9 captured by the imaging camera 15 is input to the image processing unit 30. The image processing unit 30 calculates XY coordinates of a plurality of electrodes provided on the semiconductor chip 9 based on the image signal.

The electrode coordinate signals calculated by the image processing unit 30 are input to the driving unit 29. The drive unit 29 drives the XY table 2 in the XY directions based on the coordinate signal from the image processing unit 30, and sequentially positions the plurality of electrodes provided on the semiconductor chip 9 below the laser displacement gauge 14.

The electrode of the semiconductor chip 9 is a laser displacement meter 14
, The height position of the electrode is detected by the laser displacement meter 14. Laser displacement meter 1
The detection signal of No. 4 is input to the height calculator 26 via the amplifier 24 and the A / D converter 25, and the height position (Z) of each electrode is calculated as the position of the drive target.

The calculated value calculated by the calculation unit 26 is input to a target position calculation unit 27. This target position calculator 27
Calculates the driving curve X of the bonding tool 4b shown in FIG. 2A based on the height of the electrodes, and controls the driving of the pulse motor 11 by the driving unit 29 based on the calculated driving curve X. .

The height position of the bonding tool 4b driven based on the driving curve X is detected by the position sensor 12. The detection signal from the position sensor 12 is input to the comparison unit 28. The comparison unit 28 compares the target position calculation unit 27 with the detection signal from the position sensor 12. Thus, the height of the bonding tool 4b is set with high accuracy based on the drive curve X calculated by the target position calculation unit 27.

The driving curve X of the bonding tool 4b set by the target position calculator 27 is shown in FIG.
As shown in (a), the bonding tool 4b is driven at a high speed in a direction approaching the drive target until the ball 7a of the wire 7 formed at the lower end of the bonding tool 4b contacts the electrode of the semiconductor chip 9. And a bonding step F in which the balls 7a are pressed and heated to the electrodes of the semiconductor chip 9 for bonding.
And a lifting step G for raising the bonding tool 4b at a high speed after bonding.

Next, the procedure for bonding the wires 7 to the electrodes of the semiconductor chip 9 by the bonding apparatus having the above configuration will be described with reference to the flowchart of FIG. First, if the semiconductor chip 9 is transported by the conveyor 10 to a position corresponding to the bonding head 1,
The semiconductor chip 9 is imaged by the imaging camera 15. The imaging signal of the imaging camera 15 is input to the image processing unit 30,
The XY coordinates of the plurality of electrodes provided on the semiconductor chip 9 are calculated.

Next, the XY table 2 is driven based on the XY coordinates of each electrode calculated by the image processing unit 30, and each electrode of the semiconductor chip 9 is sequentially positioned below the laser displacement gauge 14. The laser displacement meter 14 detects the height of each electrode provided on the semiconductor chip 9 with a laser beam L as an analog signal, and the detected signal is output from the A / D converter 2.
The digital signal is converted into a digital signal at step 5 and input to the height calculating unit 26. The height calculator 26 calculates the target height of each electrode as a drive target based on the detection signal of the laser displacement meter 14, and outputs the target height to the target position calculator 27.
In the target position calculator 27, a drive curve X based on the target height of each electrode is set.

Next, when the XY table 2 is driven by the driving unit 29 and the bonding tool 4b is positioned above a predetermined electrode, the bonding tool 4b, that is, the ultrasonic horn 4a is moved based on the driving curve X of the electrode. The high-speed lowering step E, the bonding step F, and the high-speed raising step G are driven in this order.

That is, the bonding tool 4b is driven in a descending direction at a high speed until just before the ball 7a formed at the tip of the wire 7 comes into contact with the electrode. Then, the bonding tool 4b is driven at a high speed in the ascending direction.

Therefore, the bonding tool 4b is lowered at a high speed to a position at which the ball 7a is bonded to the electrode, and then the bonding step F is performed, so that the time required during that time can be reduced.

Even if the bonding tool is moved down to the bonding position at a high speed, the ball 7a formed on the wire 7
The lowering position of the ultrasonic horn 4a is controlled so as not to collide with the electrode. That is, as shown by the pressing curve Y in FIG.
Since the ball 7a does not collide with the electrode before the pressing force is applied and the impact force is not applied, the ball 7a does not collapse before bonding.

In the bonding step F, the crushing allowance of the ball 7a can be controlled to a predetermined amount, so that the ball 7a can be reliably pressed against the electrode and crushed for bonding. Therefore, it is possible to avoid a defect that the ball 7a is crushed more than necessary and short-circuits with an adjacent electrode.

When the bonding to one electrode is completed, the XY table 2 is driven to position the next electrode of the semiconductor chip 9 at the bonding position, and the electrode detected by the laser displacement meter 14 with respect to this electrode. The bonding including the above-described high-speed descending step E, the bonding step F, and the high-speed ascending step G is performed according to the driving curve X based on the height position. Then, the other electrodes are also bonded according to the drive curve X based on the height position of the electrode detected by the laser displacement meter 14, respectively.

In this embodiment, when the bonding tool 4b is lowered based on the driving curve X, the lowering position is set immediately before the ball 7a formed at the tip of the wire 7 contacts the electrode. It may be up to the position where 7a comes into contact with the electrode. In short, it is sufficient to lower the capillary 4b to such a level that the ball 7a is not impacted and crushed, and can be immediately shifted to the bonding step.

The present invention is applicable not only to the case where the wires 7 are bonded to the electrodes of the semiconductor chip 9 but also to the case where the wires 7 are bonded to the leads of the lead frame 8.
By detecting the height of the position where the wire 7 of the lead is bonded by the laser displacement meter 14, the same bonding as in the above embodiment can be performed.

FIGS. 4 and 5 show a second embodiment of the present invention. In this embodiment, first, a lead frame 8 provided with a semiconductor chip 9 as shown in FIG.
The semiconductor chip 9 is placed on a Y table 41 and
XY coordinates are detected by imaging with the imaging camera 15A, and the height of each electrode is detected by the laser displacement meter 14 based on the detection result.

The first XY table 41 uses the semiconductor chip 9
Is detected, the lead frame 8 provided with the semiconductor chip 9 is supplied to the second XY table 42 by a robot (not shown). In the second XY table 42, the second imaging camera 15
B, an image of the semiconductor chip 9 is taken, the XY coordinates of the electrode serving as the bonding surface are calculated by the image pickup signal, and then the driving curve X determined according to the height of the electrode of the semiconductor chip 7 detected by the laser displacement meter 14. , The ball 7a of the wire 7 is bonded to each electrode.

The XY coordinates of each electrode during bonding are imaged by the second imaging camera 15B, and the second XY table 42 is driven based on the image signal.

That is, in the second embodiment, the first XY table 41 and the second XY table 42 detect the heights of the electrodes for different semiconductor chips 7 respectively.
Since bonding to the electrode whose height has been detected can be performed in parallel, productivity can be improved accordingly.

FIG. 5A shows a flowchart for detecting the height position of the electrode of the semiconductor chip 9 provided on the first XY table 41, and FIG. The ball 7 is provided on the electrode of the semiconductor chip 9 provided.
4 shows a flowchart for bonding a.

FIGS. 6 to 8 show a third embodiment of the present invention. FIG. 1 shows a bonding apparatus according to this embodiment.
However, the driving curve for controlling the driving of the bonding tool 4 is different.

FIG. 6 is a schematic diagram of the control device 21A.
The control device 21A includes a control unit 51. The control unit 51 outputs a drive signal based on the drive curve Z shown in FIG. The driving section 52 is provided with the swing arm 3
Is driven to swing based on the drive curve Z. When the swing arm 3 is driven to swing, similarly to the first embodiment, the ultrasonic horn 4a is interlocked with this, and the bonding tool 4b provided at the tip of the ultrasonic horn 4a moves up and down. The height position of the bonding tool 4b is the position sensor 1.
2, and the detection signal is fed back to the control unit 51.

As shown in FIG. 7, the driving curve Z has a high speed lowering step E, a constant speed lowering step e, a bonding step F, and a raising step G. In the transition from the high-speed lowering step E to the low-speed lowering step e, the bonding tool 4b is lowered by the position sensor 12 to a predetermined height (a height at which the ball 7a formed on the wire 7 does not hit the electrode of the semiconductor chip 9). The switching from the low-speed lowering step e to the bonding step F is performed based on a change in the acceleration of the swing arm 3 detected by the acceleration sensor 53.

The acceleration sensor 53 is connected to the swing arm 3
It is provided in. The acceleration sensor 53 measures the acceleration of the swing arm 3 and inputs the measured value S to the comparator 54. The set value V is set in the comparing unit 54, and the set value V and the measured value S are compared, and the measured value S is set to the set value V
If it becomes larger, a control signal is output from the comparing section 54 to the control section 51.

That is, when the swing arm 3 is moving at a constant speed as shown in FIG. 8, no acceleration is generated in the swing arm 3, but at the time indicated by T in FIG. When the ball 7a of the bonding tool 44b the lower end of the wire 7 for dynamic strikes the electrode of the semiconductor chip 9, because the speed of the swing arm 3 is reduced, the acceleration S changes to S _1. Then, when the change in the acceleration becomes larger than the set value V, the control signal R is output from the comparing unit 54 to the control unit 51, and the bonding tool 4b shifts from the constant speed lowering step e to the bonding step F.

In other words, the bonding tool 4b is shifted from the constant speed lowering step e to the bonding step F by changing the acceleration of the swing arm 3, so that the ball of the wire 7 formed at the lower end of the tip of the bonding tool 4b At the same time that 7a hits the electrode of the semiconductor chip 9, this is detected and the bonding tool 4b is switched from the lowering operation to the bonding operation.

At this time, since the acceleration sensor has a faster response to an input than the position sensor or the speed sensor, the control can be switched relatively quickly.

As a result, the operation is shifted from the descending operation to the bonding operation before the ball 7a of the wire 7 is crushed. Therefore, similarly to the first embodiment, the allowance for the crushing of the ball 7a cannot be secured during the bonding process. It is possible to prevent the occurrence of a bonding failure or a contact failure due to excessively crushing the ball 7a.

Incidentally, also in the third embodiment,
The present invention is applicable not only to the case where the wires 7 are bonded to the electrodes of the semiconductor chip 9 but also to the case where the wires 7 are bonded to the leads of the lead frame 8.

Further, in the first to third embodiments, the inner lead bonding has been described.
The present invention can of course be applied to outer lead bonding and other bonding.

[0058]

As described above, according to the present invention, it is possible to perform wire bonding without excessively crushing a ball. Therefore, it is possible to manufacture electric components with good quality.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a bonding apparatus according to an embodiment of the present invention.

FIG. 2A is a driving curve diagram of a bonding tool,
(B) is a curve diagram of a load applied to a wire ball by a bonding tool.

FIG. 3 is a flowchart of a bonding step.

FIG. 4 is a schematic configuration diagram of a bonding apparatus according to a second embodiment of the present invention.

FIG. 5 is a flowchart of a bonding step.

FIG. 6 is a control circuit diagram showing a third embodiment of the present invention.

FIG. 7 is a driving curve diagram of a bonding tool.

FIG. 8 is an explanatory diagram of a comparison between an output of an acceleration sensor and a set value in a comparison unit and an output from the comparison unit.

9A is a driving curve diagram of a conventional bonding tool, and FIG. 9B is a curve diagram of a load applied to a wire ball by the bonding tool.

[Explanation of symbols]

 4a: Ultrasonic horn 4b: Bonding tool 7: Wire 7a: Ball 14: Laser displacement meter (detection means) 21: Control device (control means) 26: Height calculation unit 29: Drive unit

Claims (8)

[Claims] 1. A wire bonding apparatus for driving a bonding tool in a driving target direction to bond a ball formed at a tip of a wire to a work, wherein the height of a portion of the work where the wire is bonded is determined in a non-contact manner. A wire comprising: detecting means for detecting; and control means for controlling driving of the bonding tool in a drive target direction based on a detection signal from the detecting means to bond the ball to the workpiece. Bonding equipment. A control unit configured to calculate a drive target position of the bonding tool from a height position of the work detected by the detection unit; and a control unit configured to control the bonding tool based on a calculation result of the calculation unit. 2. The wire bonding apparatus according to claim 1, further comprising: a drive unit configured to control the drive in the drive target direction immediately before or until the ball comes into contact with the workpiece, and then press the ball against the workpiece. 3. A method of manufacturing an electric component for bonding a ball formed at the tip of a wire to a work by driving a bonding tool in a drive target direction, wherein the height of a portion of the work to which the wire is bonded is determined. A detecting step of detecting by contact; and a bonding step of controlling the driving of the bonding tool in a driving target direction based on a detection result of the detecting step to bond the ball to the work. Manufacturing method of electrical parts. 4. The bonding step includes: a driving target step of driving the bonding tool immediately before or until the ball comes into contact with the work; and a driving target step of driving the bonding tool until the ball comes into contact with the workpiece. 4. The method for manufacturing an electric component according to claim 3, further comprising a pressing step of pressing the work. 5. The method for manufacturing an electric component according to claim 3, wherein the bonding step is performed after the detection step is performed on the work. 6. The method for manufacturing an electrical component according to claim 3, wherein the detecting step and the bonding step are performed independently for different works. 7. A wire bonding apparatus for driving a bonding tool in a drive target direction to bond a ball formed at the tip of a wire to a workpiece, a driving unit for driving the bonding tool in a drive target direction, and the bonding tool. An acceleration detecting means for detecting a change in acceleration of the bonding tool when the ball comes into contact with the work by driving the driving tool in a drive target direction, based on a change in acceleration detected by the acceleration detecting means. Control means for controlling the driving of the bonding tool in the drive target direction. 8. A method of manufacturing an electric component for driving a bonding tool in a drive target direction to bond a ball formed at the tip of a wire to a workpiece, wherein the driving step drives the bonding tool in the drive target direction. The bonding tool is driven in the drive target direction based on the change in the acceleration detected while detecting the change in the acceleration of the bonding tool when the ball contacts the workpiece by driving the bonding tool in the drive target direction. And a control step of controlling driving.