JPS61236132A - Bonding process in wire bonding apparatus - Google Patents

Abstract

PURPOSE:To avoid any defective bonding process due to misoperation of a contact detector 12 by a method wherein the bonding process is performed using a slide block under elastic load of an energizing means. CONSTITUTION:A controller 2 controls the lifting and lowering operations of a slide block 1 conforming to various data stored in a memory 2b. The block 1 is rapidly lowered from the top dead center H to the position immediately before contact M to be slowly lowered from the position immediately before contact M to the bottom dead center L at specified distant DELTAH low speed. During the lowering operation, a capillary 5 in contact with the bonding surface performs the first bonding process I making use of the elastic load of a spring 6a due to clockwise rotation of a bonding arm 3 caused by the lowering action of the slide block 1. The slide block 1 is lifted rapidly to reach the top dead center H in the second bonding process II. While the slide block 1 is stopped at the top dead center H, an XY table is shifted to locate and electrode 8b at the position immediately below the capillary 5. Likewise the slide block 1 is lifted and lowered to perform the second bonding process II.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a bonding method in a wire bonding apparatus that connects an element side electrode of a workpiece such as a semiconductor device and an external lead electrode using a thin metal wire.

Conventional technology As a conventional wire bonding device, patent application No. 58-2
There is one shown in the No. 40211 application. Since the present invention is an improvement on the bonding method using this conventional device, the conventional device will first be explained based on FIGS. 2 and 3.

In FIG. 2, 1 is a slide block whose lifting position and speed are controlled by control means 2, 3 is a bonding arm rotatably supported by the slide block via a pivot 4, and 5 is the tip of the bonding arm 3. A capillary 6 attached to the bonding arm 3 is a biasing means for applying an elastic load to the bonding arm 3.

A semiconductor device a as a workpiece is set on the XY table 7, and its element side electrode 8a and external lead electrode 8b
The device operates in such a way that the thin metal wire supplied to the capillary 5 connects the two.

The slide block 1 is raised and lowered by the drive of a linear motor 9, and its raising and lowering position and speed are controlled by a control means 2 comprising a main control circuit 2a, a memory 2b, a drive circuit 20, and the like.

The biasing means 6 is attached to the bonding arm 3 by lever 1.
0, and a solenoid 6b that applies an elastic load (electromagnetic attraction force) to the bonding arm 3 via the lever 10 only when energized.

The bonding arm 3 is composed of an ultrasonic horn, and transmits the vibration of the ultrasonic vibrator 11 to the capillary 5.

Next, a method of controlling the vertical movement of the slide block 1 in the device will be explained based on FIG. 4.

FIG. 4 shows the ascending and descending positions of the slide block 1 over time. The left half shows the first bonding process I (see FIG. 2) for bonding the element side electrode 8a of the semiconductor device a, and the right half shows the second bonding process I for bonding the external lead electrode 8b.
(See 3rd vI!J), but both are basically controlled in the same way.

In FIG. 4, H is the preset top dead center position, S is the preset search position, and C is the vertical position (contact) of the slide block 1 when the capillary 5 first contacts the bonding surface of the semiconductor device a. position), L is the bottom dead center position.

The contact position C is determined by using the fact that the vibration waveform of the ultrasonic vibration changes when the capillary 5 contacts the bonding surface. Detected by 12 (
(See Figure 2). The bottom dead center position is the contact position fi! It is set a certain distance (for example, 0°2 cranes) ΔL below c.

Thus, as shown in FIG. 4, the slide block 1 descends at high speed from the top dead center position H to the search position S, and then changes to a low speed and gradually descends until it reaches the contact position Rc.
When the contact position C is detected by the contact detection device 12, the contact position C is further lowered by the fixed distance ΔL at a low speed, and reaches the bottom dead center position (in addition, the broken line in FIG. 4 indicates that the capillary 5
It shows the movement. ).

Bonding is performed while the slide block 1 is from the contact position C to the bottom dead center position, and in the first bonding process (2), the elastic load by the spring 6a is applied, and in the second bonding process (2), the elastic load is applied to the spring 6a. Elastic loads are applied from the capillary 5 to the bonding surface by the solenoid 6b.

Problems to be Solved by the Invention According to the above conventional method, it is essential that the contact position C be detected accurately by the contact detection device 12. However, the contact detection device 12 may malfunction due to the influence of the material of the bonding surface, the vibrations of the capillary 5, the bonding arm 3, etc.

For example, if the contact detection device 12 malfunctions before the capillary 5 comes into contact with the bonding surface, the slide block 1 will then descend only by the predetermined distance ΔL, so the elastic load applied from the biasing means 6 to the capillary 5 will be insufficient. As a result, proper bonding will not be performed, and in extreme cases, bonding will not be possible. On the other hand, if the contact is not detected by the contact detection device 12, the elastic load becomes excessive, and bonding failure also occurs in this case.

Means for Solving the Problems In order to solve the above problems, the method of the present invention includes: ° A bonding arm with a capillary attached is rotatably supported on a slide block whose lifting position and speed are controlled by a control means. A wire bonding device comprising: a biasing means for applying an elastic load to the capillary in accordance with the rotation of the bonding arm when the capillary contacts a bonding surface of a workpiece and the bonding arm rotates; In this step, a contact position as a rising/lowering position of the slide block when the capillary first contacts the bonding surface is determined in advance, and a position immediately before contact and a bottom dead center position that approach above and below this contact position are set. , these are stored in the control means together with the top dead center position of the slide block, and the descending speed of the slide block from the top dead center position to the position immediately before contact and the descending speed of the slide block from the position immediately before contact to the bottom dead center position is stored in the control means, and based on these data, the slide block is lowered from the top dead center position to the position immediately before contact, and then lowered from the position immediately before contact to the bottom dead center position.

Function The present invention has the above-mentioned configuration, and as shown in FIG. 1, the slide block descends at high speed from the top dead center position H to the position M just before contact, and then descends at a predetermined low speed by a certain distance ΔH. Bonding can be performed while the dead center position is reached. Further, in the present invention, since the contact position is not detected as in the conventional example, there is no adverse effect due to malfunction of the contact detection device. Therefore, according to the present invention, since there is no large difference in the descending distance of the slide block from when the capillary first contacts the bonding surface until it reaches the bottom dead center position, the elastic load during bonding can be adjusted to an appropriate value. As a result, the problem of poor bonding seen in the conventional example can be solved.

EXAMPLE Hereinafter, a bonding method in a wire bonding apparatus according to an example of the present invention will be described with reference to the drawings.

The wire bonding apparatus shown in FIGS. 2 and 3 has basically the same structure as the conventional apparatus, but differs in that it does not have the contact detection bag fit12 shown by the imaginary line.

The slide block 1 is a guide rod 1 provided on the machine frame 13.
4 and move up and down. This vertical movement is performed by driving a linear motor 9, which includes a center pole 9a fixed to the machine frame 13 side, a yoke 9b,
It is composed of a magnet 9c, a bobbin 9d fixed to the slide block 1 side, and a coil 9e.

A bonding arm 3 composed of an ultrasonic horn is rotatably supported on the slide block 1 via a pivot 4. A capillary 5 is attached to the tip of this bonding arm 3, to which gold imi*b is supplied. Also, an ultrasonic horn 1 is installed at the base end of the bonding arm 3.
An ultrasonic vibrator 11 excited by 8 is attached.

6a moves the bonding arm 3 to the second position via the lever 10.
A spring biasing counterclockwise in the figure acts on the bonding arm 3 during first bonding and second bonding. In other cases, the lever 10 is moved to the stopper 15.
is in contact with.

A solenoid 6b attracts the suction plate 16 when energized and uses its electromagnetic attraction force to urge the bonding arm 3 counterclockwise in FIG. 2 via the lever 10. A power supply command is issued from the main control circuit 2a of the control means 2 during the second bonding, and the solenoid 6b energizes the bonding arm 3. Note that 17 is an auxiliary spring with a weak spring force.

The lifting position and lifting speed of the slide block 1 are controlled by a control means 2. This control means 2 includes a main control circuit 2a, a memory 2b, and a drive! It is composed of an lJ circuit 2c and the like. Note that 19 is a position sensor that detects the vertical position of the slide block 1, and 20 is a speed sensor that detects the vertical speed of the slide block 1.

The XY table 7, which fixedly supports the semiconductor device a as a workpiece, performs predetermined movements in two directions, XY and Y, based on commands from the main control circuit 2a.

The memory 2b of the control means 2 stores information regarding the contact position predetermined as the vertical position of the slide block 1 when the capillary 5 first contacts the bonding surface.
A position immediately before contact M, which is a position close to the bottom of the contact position, and a bottom dead center position, which is a position close to the bottom of the contact position, are stored together with the top dead center position H of the slide block 1.

The descending speed of the slide block 1 from the upper dead center position H to the position M immediately before contact and the descending speed of the slide block 1 from the immediately before contact position M to the bottom dead center value EL are also stored in the memory 2b.

The distance ΔH between the position M immediately before contact and the bottom dead center position is set to, for example, 0.5 fl. The speed of descent from the position M immediately before contact to the bottom dead center position is set to be low compared to the speed of descent from the position H immediately before contact to the position M immediately before contact.

As shown in FIG.
The only difference is the height difference of 8b.

Thus, the control means 2 controls the vertical movement of the slide block 1 as shown in FIG. 1 based on the various data stored in the memory 2b.

First, in the first bonding step (3), the slide block 1 descends at high speed from the top dead center position H to the position M immediately before contact (at this time, for example, the capillary 5 is placed at a height of approximately 0.3 mm directly above the bonding surface of the electrode 8a). Become.). Next, a certain distance ΔH (for example, 0
．． 5 tm) Descend at low speed. During this time, the capillary 5 is in contact with the bonding surface as shown by the broken line in FIG. 1 and as shown in FIG. The first bonding action is performed using the elastic load of.

After the slide block 1 is located at the bottom dead center and stops opening at a predetermined time, it rises at high speed and reaches the top dead center position H in the second bonding step (2).

While the slide block 1 is stopped at the top dead center position H, the XY table moves so that the electrode 8b is positioned directly below the capillary 5. Next, the slide block 1 is raised and lowered in the same way as in the first bonding process (■), and the second
Perform bonding. However, in the second bonding step (2), the solenoid 6b is energized and bonding is performed in a state where the elastic loads of both the spring 6a and the solenoid 6b are applied.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, the vertical position of the slide block 1,
Of course, the motion characteristics related to the lifting speed are not limited to those shown in FIG.

Effects of the Invention The present invention has the above configuration, in which the position just before the contact of the slide block and the bottom dead center position are accurately set in advance, and when the slide block descends between these at low speed, the capillary connects the workpiece to the bonding point. Bonding is performed in a state where the capillary is in contact with the bonding surface and an elastic load is applied by the biasing means, and the descending distance of the slide block from when the capillary first contacts the bonding surface until reaching the bottom dead center position is large. Since no difference occurs, the elastic load during bonding can be maintained at an appropriate value.

Therefore, according to the present invention, it is possible to solve the problem of defective bonding due to malfunction of the contact detection device in the conventional example.

[Brief explanation of drawings]

Fig. 1 is a movement characteristic diagram of a slide block in an embodiment of the present invention, and Fig. 2 is a partially longitudinal side view showing an example of a wire bonding device used in the present invention (however, the portion indicated by imaginary lines is conventional 3 is a side view of the main parts showing its operation, and FIG. 4 is a diagram showing the motion characteristics of the slide block in a conventional example. t－－－－－－－・・・－－－－－－－１・・・－・
−−−1・・−・・−・・Slide block 2−・−・
−1−−−・−・−−1−−−−−・−・・−Control means 3・−・−・−・・−・−・−−1−・−−1−−・
−・−−−−1・Bonding arm 5−・−1−−−
−−−−−−・−・−・・−・−・−11−−−−Capillary 6−・−・−・・−・−・−・・−・・−・−
・-11～～Biasing means a～・～------------
・−・−・−・・−・−−1−−−Workpiece H−・−・
−・−１１−−−−−−・−−１−−・−・−・−−−
−−−Top dead center position M−−−−・−1～−1−・・−
・−・−・−−−−−−1−−・−・−Position L just before contact
−・−・−・−−−１−−−・・−−−−−−〜−−−
−−−−・−・Bottom dead center position. Applicant Matsushita Electric Industrial Co., Ltd. Agent Patent Attorney Toshio Nakao 1 person Figure 1 Figure 4 Ginmon-

Claims (1)

[Claims] (1) A bonding arm with a capillary attached is movably supported by a slide block whose lifting position and speed are controlled by a control means, and the bonding arm moves as the capillary comes into contact with the bonding surface of the workpiece. In a wire bonding apparatus comprising a biasing means for applying an elastic load to the capillary in accordance with the movement of the bonding arm, the slide block is in an ascending and descending position when the capillary first contacts the bonding surface. A contact position is determined in advance, and a position immediately before contact and a bottom dead center position that approach above and below this contact position are set, and these are stored in the control means together with the top dead center position of the slide block, and the top dead center The descending speed of the slide block from the position immediately before contact to the position immediately before contact and the descending speed of the slide block from the position immediately before contact to the bottom dead center position are stored in the control means, and based on these data, the slide block is brought into contact from the top dead center position. A bonding method in a wire bonding apparatus, characterized in that the wire bonding device is lowered to a position immediately before contact, and then lowered from the position immediately before contact to a bottom dead center position.