JPS5916135B2 - cam drive mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bonding device having a cam drive mechanism, and is mainly directed to a vertical drive mechanism for a bonding arm in a wire bonding device, and to operate the bonding arm reliably even at high speeds. The purpose of the present invention is to provide a cam drive mechanism that provides a flexible cam drive mechanism.

Generally, a wire bonding apparatus performs a wire bonding operation in which a wire such as a gold wire 0 is used to connect a bonding pad on a semiconductor pellet to a lead.

In this case, the capillary that guides the wire and performs bonding is moved horizontally above the pellet to a predetermined position for bonding using a pulse motor, etc., and when the capillary reaches the predetermined position, the capillary is moved vertically above the pellet. move it to Conventionally, a cam drive mechanism has been used as a means for vertically driving the capillary, and an example thereof is shown in FIG.

That is, the bonding arm '01 has a fulcrum 2 at its center, and a capillary 3 is held at one end thereof. A cam follower 5 that follows the cam 4 and moves periodically in the vertical direction in the figure is in contact with the other end of the bonding arm 1. Following the vertical movement of the cam follower 5, the j5 bonding arm 1 is activated by a spring. It is rotationally displaced by 6. Note that the spring 1 is attached to the cam follower 5 mentioned above.
It has the effect of ensuring that the movement of but,
In the cam drive mechanism as described above, when the capillary 3 is operated at high speed to increase the bonding speed,
Due to the inertia of the cam follower 5 and bonding arm 1,
When the cam 4 and the cam follower 5 or the cam follower 5 and the bonding arm 1 are separated, the bonding arm 1
does not move as desired, making it impossible to perform the desired bonding.

In this case, methods for solving the above technical problems include increasing the spring constants of the springs 6 and 7, reducing the inertia of the cam follower 5 and bonding arm 1, and selecting the cam shape of the cam 4. There are methods such as reducing the cam lift.

However, even with these methods, it is necessary to limit the bonding speed in order to ensure that a predetermined bonding is performed. The present invention eliminates the above-mentioned drawbacks, and one embodiment thereof will be described below with reference to FIGS. 2 and 3. FIG. 2 is a schematic mechanical diagram of an embodiment of a bonding device having a cam drive mechanism according to the present invention;
FIG. 3 is a schematic diagram showing the operation of the bonding apparatus shown in FIG. 2.

In Figure 2, the bonding arm part is shown in
Components that are the same as those in the figures are designated by the same reference numerals, and their explanations will be omitted.

In FIG. 2, cams 8a and 8b are fixed to the same support shaft 9 at a predetermined distance from each other. 10a, 10b
is a cam follower which contacts the cam surfaces of the cams 8a and 8b, respectively, and converts the rotational motion of the cams 8a and 8b into periodic rocking motion.

Each of these cam followers 10a and 10b has a lever 1.
1a, 11b are fixed, levers 11a, 11b
is supported on a pivot with the bearing 12 as a fulcrum. Therefore, the levers 11a and 11b are connected to the cam follower 10.
A, 10b, a predetermined rotational movement about the bearing 12 is repeatedly performed. In this case, these levers 11
At predetermined positions of a and 11b, springs 13a and 1 are installed, respectively.
3b is stretched, so that the cam 8a and the cam follower 10a, and the cam 8b and the cam follower 10b are always in contact with each other. Therefore, when the pellet or lead surface and the capillary, that is, the bonding connection tool, come into contact, Even during driving, the movement of the cams 8a, 8b is reliably controlled by the cam followers 10a, 10b (that is, the levers 11a, 1
1b). 14a and 14b are rollers, which are rotatably provided at one end of the levers 11a and 11b, respectively.Moreover, the rollers 14a and 14b are provided at the end of the bonding arm 1 opposite to the end where the capillary 3 is installed. It is in contact with the bonding arm 1 so as to sandwich the bonding arm 1.

The bonding arm is displaced by a displacement mechanism consisting of the cam follower and lever roller.The cam follower 10a, lever 11a, and roller 14a are the first displacement mechanism, and the cam follower 10b, lever 11b, and roller 14b are the second displacement mechanism. be. These displacement mechanisms are driven by a drive mechanism having a cam 8a and a cam 8b, that is, a cam drive mechanism. Note that 15 is a spring for applying bonding pressure to the capillary 3, that is, a mechanism for applying bonding pressure to the bonding arm. Next, the operation of the bonding apparatus having the cam drive mechanism configured as described above will be explained.

When the cam 8a rotates in the direction of the arrow shown in the second figure, the cam follower 10a in contact with it is displaced leftward in the figure following the cam 8a.

When the cam follower 10a is displaced, one drive displacement amount is transmitted to the bonding arm 1 by the lever 11a and the roller 14a. As a result, the bonding arm 1 is driven in the direction in which the capillary 3 is lowered onto the pellet surface. At this time, the other cam 8b also rotates in the same direction as the cam 8a, but its rotational movement causes the cam follower 10b and roller 14b to apply a force to the bonding arm 1 in the opposite direction to the driving force exerted by the cam 8a. .

The force by this cam 8b is a force in the opposite direction to the driving force by the cam 8a (bonding arm 1 and roller 1
4a as the same system). This force in the opposite direction restrains the bonding arm 1 from springing up due to the positive writing force, and prevents the arm 1 from separating from the roller 14a. In this way, at the bonding position where the capillary 3 has descended to the level of the pellet surface (or lead surface), the bonding arm 1
It is separated from roller 14a and roller 14b.

That is, a predetermined bonding pressure is applied to the capillary 3 at one end of the bonding arm 1 by the spring 15 to perform bonding. The operation of the bonding apparatus described above will be further described based on FIGS. 3a to 3c.
First, FIG. 3a shows the state of the bonding arm 1 and capillary 3 before bonding.

As can be seen from Figure A, the rollers 14a and 14b are in contact with the bonding arm 1 at the end thereof. At this time, rollers 14a and 14b
The distance between them is W. FIG. 3b shows that the bonding arm 1 is moved so that the end portion of the bonding arm 1 having the capillary 3 descends toward the punch ink point (pellet surface or lead surface) by the rotation of the cam 8a as described above. The case of driving is shown. As can be seen from FIG. 3b, the rollers 14a and 14b are in contact with the bonding arm 1 at the end of the bonding arm 1, as in the case of FIG. 3a. That is, as described above, the driving force by the cam 8a is applied to the bonding arm 1 via the roller 14a, and the force in the opposite direction to the driving force by the cam 8b is applied to the bonding arm 1 via the roller 14b. be. Further, FIG. 3c shows a state in which the capillary 1J3 provided in the bonding animation 1 has been lowered to the bonding point. As shown in FIG. 3b, when the punch ink arm 1 is driven and the capillary 3 approaches the bonding point (pellet surface), the distance between the rollers 14a and 14b is W2 (W2>W).
1), and the rollers 14a, 14b are separated from the punch ink arm 1.

The bonding arm 1 is driven by the spring 15, and the capillary 3 reaches the bonding point. After the above bonding is completed, a driving force is applied to the bonding arm 1 via the cam follower 10b, the lever 11b, and the roller 14b.

As a result, the above-mentioned cavity 3 shifts to a rising operation,
Immediately after it leaves the pellet surface (or lead surface), the roller 14a, which has been separated from the bonding arm 1, comes into contact with the bonding arm 1, and in this state, the capillary rises. In this state, the bonding arm 1 is in a state in which a driving force is applied by the roller 14b (ie, the cam 8b) and a restraining force is applied by the roller 14a (ie, the cam 8a). In this way, the capillary 3 reaches the height position before bonding.

Then, as the capillary rises, the capillary 3
As is well known, the lead surface (or pellet surface) is moved to a predetermined position for bonding using a pulse motor or the like. Subsequently, the punch ink operation of the capillary 3 is performed in the same manner as described above. As described above, according to the bonding device having the cam drive mechanism according to the present invention, there are two cams that move the driven body such as the bonding arm, one of which is used as a driving cam and the other is used as a restraining cam. Unlike the conventional method in which the link system is driven by the force of a spring, the link system can be driven while being restrained by two cams without being affected by the inertia of the link system itself. The link system can follow rapid changes in the cam profile, and can also effectively prevent the link system from jumping up due to sudden forces received from the cam profile.This allows driven objects such as the bonding arm to operate reliably even at high speeds. It has features that can make it possible to

[Brief explanation of drawings]

Fig. 1 is a schematic mechanical diagram showing an example of a conventional cam drive mechanism of this type, Fig. 2 is a schematic mechanical diagram of an embodiment of a bonding apparatus having a cam drive mechanism according to the present invention, and Figs. 3 a-c.
2 is a schematic diagram showing the operation of the bonding apparatus shown in FIG. 2. FIG. 1... Bonding arm, 3... Capillary, 8a, 8b... Cam, 10a, 10
b...Cam follower, 11a, 11b...
...Lever, 13a, 13b...Spring,
14a, 14b...mouth, 15...
spring.

Claims (1)

[Claims] 1. A bonding arm that has a fulcrum and is capable of moving up and down in a rotational direction about this fulcrum, and a bonding arm that guides a wire and performs bonding of the wire to a wire-bonded body; and a pair of first and second bonding tools for vertically displacing the arm in a rotational direction about the fulcrum at a position away from the fulcrum of the arm. a displacement mechanism; first and second cam drive mechanisms for driving the first and second displacement mechanisms; and a mechanism for applying bonding pressure to the arm; The contact portions of the second displacement mechanism that contact the arm are arranged to face each other with respect to the arm so as to vertically displace the arm in a rotational direction about the fulcrum, and The distance between the abutting portions of the pair of first and second displacement mechanisms on the arm during bonding is made larger than the distance during the process of displacing the arm to the bonding position, and during the bonding, the distance between 1. A bonding device having a cam drive mechanism, characterized in that said arm is configured to be displaced by a mechanism that applies pressure.