JPH0431179B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wire bonding device for connecting an element side electrode of a semiconductor device and an external lead electrode with a thin metal wire.

BACKGROUND ART A conventional wire bonding apparatus will be explained based on FIGS. 4 to 7.

In FIG. 5, reference numeral 1 denotes a slide block whose lifting position and speed are controlled by a control means 2, and which moves up and down along a guide rod 14 of a machine frame 13;
3 is a bonding arm rotatably supported by the slide block 1 via a pivot 4, 5 is a capillary attached to the tip of the bonding arm 3, and 6
is a biasing means that applies an elastic load to the bonding arm 3.

A semiconductor device a is set on the XY table 7, and the device is operated so that its element side electrode 8a and external lead electrode 8b are connected by a thin metal wire b supplied to the capillary 5.

The slide block 1 is raised and lowered by the drive of a linear motor 9, and its raising/lowering position and speed are controlled by a control means 2 comprising a main control circuit 2a, a memory 2b, a drive circuit 2c, etc. Further, the linear motor 9 is connected to the machine frame 13.
A center pole 9a fixed to the 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.

The biasing means 6 is a spring 6a which is always connected to the bonding arm 3 via a lever 10.
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 solenoid 6b attracts the attraction plate 16 when energized, and urges the bonding arm 3 by its electromagnetic attraction force. Note that reference numeral 17 is an auxiliary spring with a weak spring force, and the urging force applied to the bonding arm 3 is negligible.

The bonding arm 3 is composed of an ultrasonic horn, and transmits the vibration of the ultrasonic vibrator 11 generated by the ultrasonic oscillator 18 to the capillary 5.

Next, the vertical movement of the slide block 1 in the device will be explained with reference to FIG.

FIG. 7 shows the ascending and descending positions of the slide block 1 over time. The left half shows the first bonding step (see FIG. 5) for bonding the element side electrode 8a of the semiconductor device a, and the right half shows the second bonding step (see FIG. 6) for bonding the external lead electrode 8b.
However, both are basically controlled in the same way.

In FIG. 7, 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 detected by the contact detection device 12 using the fact that the vibration waveform of ultrasonic vibration changes when the capillary 5 contacts the bonding surface (see FIG. 5). The bottom dead center position L is a certain distance (for example, 0.2 mm) ΔL from the contact position C.
It is defined below.

Thus, as shown in FIG. 7, the slide block 1 descends at high speed from the top dead center position H to the search position S, then switches to a low speed and gradually descends while searching for the contact position C, and detects the contact. When the contact position C is detected by the device 12, it further descends at a low speed by the predetermined distance ΔL and reaches the bottom dead center position L (the movement of the capillary 5 is shown by a broken line in FIG. 7). ).

Bonding is performed while the slide block 1 is from the contact position C to the bottom dead center position L, and in the first bonding process I, the elastic load by the spring 6a is applied, and in the second bonding process, the elastic load is applied to the spring 6a and Elastic loads by the solenoids 6b are applied from the respective capillaries 5 to the bonding surfaces.

In FIG. 5, reference numeral 15 denotes a stopper, which functions to keep the bonding arm 3 substantially horizontal during non-bonding. Further, 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.

Problems to be Solved by the Invention In the conventional device having the above configuration, when the slide block 1 descends a predetermined distance ΔL from the contact position C to the bottom dead center position L, the capillary 5 contacts the bonding surface and moves downward. On the other hand, as the bonding arm 3 rotates clockwise in FIGS. 5 and 6, an elastic load is applied to the capillary 5 from the biasing means 6.

As this elastic load, an elastic load due to the elongation of the spring 6a acts during the first bonding, and an elastic load due to the electromagnetic attraction force of the solenoid 6b acts in addition to the elastic load due to the elongation of the spring 6a during the second bonding.

By the way, the electromagnetic attraction force of the solenoid 6b is
Due to the change in the gap P shown in FIG. 5 due to the rotation of the bonding arm 3 during the second bonding, the gap P changes considerably as shown in FIG. 4. In other words, the amount of change ΔF in electromagnetic attractive force with respect to the displacement ΔP of gap P
1 becomes considerably large, and the elastic load of the capillary 5 on the bonding surface changes considerably between the start of the second bonding and the end of the second bonding, which poses a problem in that it poses a problem in properly performing bonding. be.

Means for Solving the Problems In order to solve the above problems, the present invention provides a slide block that is driven so as to be able to rise and fall along the guide section of the machine frame, and a bonding arm that has a capillary attached to its tip that can be freely rotated. and a biasing means for applying an elastic load to the bonding arm, the elastic load applied from the biasing means to the capillary via the bonding arm is greater than that during the first bonding.
In a wire bonding apparatus in which the biasing force is set to be larger during bonding, the biasing means is a first spring that is always connected to the bonding arm, and a second spring that is connected to the bonding arm via an intermittent switching means. The present invention is characterized by comprising a control means for bringing the intermittent switching means into a connected state during the second bonding.

Effect Since the present invention has the above configuration, during the second bonding, the intermittent switching means is in the connected state, and the second spring is connected to the bonding arm in addition to the first spring, and the elastic load due to the expansion or contraction of these springs is applied. is applied to the capillary via the bonding arm. As shown in FIG. 3, the amount of change ΔF2 in the spring force of the second spring with respect to the displacement ΔP can be significantly reduced compared to ΔF1 in the conventional example, and as a result, the elastic load at the time of second bonding can be reduced. change can be reduced.

Embodiment A wire bonding apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The device shown in FIGS. 1 and 2 includes a biasing means 21
The structure is basically the same as the conventional device shown in FIGS. 5 and 6 except for the following.

A bonding arm 3 with a capillary 5 attached to its tip is attached to a slide block 1 which is driven so as to be able to rise and fall along a guide portion (a guide rod is used in the embodiment) 14 of a machine frame 13.
It is rotatably supported through the. The bonding arm 3 is composed of an ultrasonic horn, and transmits the vibration of an ultrasonic vibrator 11 attached to the base end to the capillary 5. The capillary 5 has an element-side electrode 8 on the semiconductor device a on the XY table 7.
A thin metal wire b is supplied for connecting the electrode a and the external extraction electrode 8b.

The biasing means 21 for applying an elastic load to the capillary 5 via the bonding arm 3 includes a first spring 21a made of a tension coil spring and a second spring 21b made of a compression coil spring.

One end of the first spring 21a is fixed to a first adjustment screw 22 screwed into the slide block 1, and the other end is fixed to the tip of a lever 10 that rotates integrally with the bonding arm 3. .

The second spring 21b is interposed between the operating rod 24 of the intermittent switching means 23 constituted by a solenoid and a second adjustment screw 25 screwed into the slide block 1.

When energized, the solenoid 23 attracts a suction plate 26 integrally formed near the left end of the operating rod 24 as shown in FIG. 1, moves the operating rod 24 to the right, and disconnects the lever 10 and the operating rod 24. Make it. The energization of the solenoid 23 is controlled based on a command from the main control circuit 2a of the control means 2, and the solenoid 23 is energized except during the second bonding.

During the second bonding, the electricity is cut off and the solenoid 23 is de-energized, so that the operating rod 24 can freely move left and right. Therefore, as shown in FIG. 2, the operating rod 24 is pushed to the left by the second spring 21b, and its left end comes into pressure contact with the lever 10.

Thus, during the first bonding, the bonding arm 3 and the second spring 21b are disconnected by the on/off switching means (solenoid) 23, so that the first
Only the elastic load from the spring 21a acts on the capillary 5 via the lever 10 and the bonding arm 3.

On the other hand, during the second bonding, the intermittent switching means (solenoid) 23 switches to connect the second spring 21b and the bonding arm 3 via the lever 10, so that the elasticity from the first spring 21a and the second spring 21b is reduced. A load acts on the capillary 5.

And the second spring 2 at the time of second bonding
The amount of change ΔF2 in the spring force with respect to the displacement ΔP of 1b is:
As shown in Fig. 3, it can be significantly reduced compared to ΔF1 of the conventional example (it is thus easy to select a spring whose spring force change ΔF2 is small with respect to displacement ΔP). . Therefore, it is possible to reduce the difference in the elastic load acting during the second bonding between the start and end of bonding, and to make the elastic load substantially constant during bonding.

In FIGS. 1 and 2, reference numeral 15 is a stopper against which the lever 10 comes into contact during non-bonding, and has the function of keeping the bonding arm 3 in a predetermined approximately horizontal position during non-bonding.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, both the first spring 21a and the second spring 21b can be tension coil springs, or conversely, both can be compression coil springs.
It is also possible to use a torsion spring other than a coil spring. It is also possible to configure the intermittent switching means 23 with an air cylinder or the like.

Effects of the Invention The apparatus of the present invention has the above-mentioned configuration, and can perform the second bonding with a substantially constant elastic load applied while reducing the change in the elastic load during the second bonding. wire bonding can be performed appropriately.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing the main parts during the first bonding of an embodiment of the present invention, FIG. 2 is a partially cutaway side view showing the main parts during the second bonding, and FIG. A graph showing the spring characteristics of the second spring, Fig. 4 a graph showing the suction force characteristics of the solenoid in the conventional example, Fig. 5 a partially cutaway side view showing the conventional example, and Fig. 6 showing the main parts thereof. The side view, FIG. 7, is a graph showing its motion characteristics. 1...Slide block, 2...Control means, 3
...Bonding arm, 5...Capillary, 2
1...Biasing means, 21a...First spring, 21b...
...Second spring, 23...Intermittent switching means.

Claims (1)

[Claims] 1. A bonding arm having a capillary attached to its tip is rotatably supported on a slide block which is driven to be able to rise and fall along the guide section of the machine frame, and a biasing means is provided to apply an elastic load to the bonding arm. In the wire bonding apparatus, the elastic load applied from the urging means to the capillary via the bonding arm is set to be larger during the second bonding than during the first bonding,
The biasing means is composed of a first spring that is always connected to the bonding arm, and a second spring that is connected to the bonding arm via an on-off switching means, and the on-off switching means is in a connected state during second bonding. A wire bonding apparatus characterized in that it is provided with a control means.