JPS6364896B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention involves introducing a wire led out from a wire feeding device of a bonding device into a bonding tool via a clamp, bonding it to a pellet, and then bonding it to a lead frame. The present invention relates to a wire bonding device that reliably controls the loop shape of a wire.

[Technical background of the invention and its problems]

In the assembly process of semiconductor devices, a bonding apparatus as shown in FIG. 1 is generally used as a means for connecting pellets and lead frames with wires. Reference numeral 1 in FIG. 1 is a main body of the device, and a feeding device 2 such as a wire spool having a clamp portion 2a is provided on the upper part of the main body 1. A wire guide 4 for guiding the wire 3 is provided on the wire feeding side of the main body 1. This wire guide 4 consists of a leaf spring whose base end is attached to the attachment part 5 of the main body 1 so as to be able to swing vertically. The amount of downward swinging is regulated by a stopper 7 provided at. Further, a curved portion 8 for guiding the wire 3 downward is formed at the free end of the wire guide 4. An upper clamp 9 for clamping and releasing the introduced wire 3 is provided at the lower part of the curved portion 8 of the wire guide 4. The upper clamp 9 is supported by an arm 9a projecting from the side of the main body 1, and is opened and closed by a solenoid (not shown) to clamp and release the wire 3. A tube-shaped wire guide 10 is attached to a swing arm 12 of a lower clamp 11 below the upper clamp 9, and is adapted to guide the wire 3 to the lower clamp 11. This lower clamp 11 is provided at the tip of the swing arm 12, and is opened and closed by a solenoid (not shown) to clamp and release the wire 3. A capillary arm 13 is provided below the swing arm 12 and parallel to the swing arm 12. A bonding tool 14 through which the wire 3 is inserted is provided at the tip of the capillary arm 13. This capillary arm 13 is connected to the base end of the swing arm 12 of the lower clamp 11 and the leaf spring 13a.
The swing arm 12 is connected to the swing arm 12 via a swing shaft 15, and pivots in the vertical direction about a swing shaft 15 that pivotally supports the base end of the swing arm 12. That is, the wire guide 10, the lower clamp 11, and the bonding tool 14 are integrally moved in the vertical direction. Note that a torch 16 or a spark electrode is provided below the bonding tool 14 to heat the tip of the wire 3 protruding below the bonding tool 14 to form a ball 17. Then, the pellet 18 and lead frame 19 are placed below the bonding tool 14, and the ball 17 is placed under the pellet 18.
After bonding, the wire 3 is bonded to the lead frame 19 to connect the pellet 18 and the lead frame 19, thereby performing bonding.

The operation of this conventional bonding apparatus will be explained in more detail with reference to FIG. A shows the state before the bonding operation starts, and in this A the upper clamp 9
is closed and the lower clamp 11 is open, the wire 3
Apply an appropriate frictional force to the Next, when the bonding tool 14 is lowered as shown in B, the ball 17 at the tip of the wire 3 comes into close contact with the bonding tool 14 because the upper clamp 9 applies a frictional force to the wire 3. The bonding roots 14 then descend further and press the balls 17 onto the pellets 18 as shown in C. The upper clamp 9 is opened before the ball 17 is pressed onto the pellet 18. Then, the bonding tool 14 is raised and the lead frame 19 is moved up as shown in D.
to the second bonding position. Then,
The bonding tool 14 descends between E and F, and the wire 3 is crimped onto the lead frame 19.
Among these, the bonding tool 14 rises and the G
At , the lower clamp 11 is closed and the wire 3 is cut off from the lead frame 19. The bonding tool 14 is further raised to H, a ball 17 is formed at the tip of the wire 3 by the torch 16, and one cycle is completed.

By the way, in the conventional wire bonding apparatus, when the ball 17 is crimped onto the pellet 18 as shown in FIG. However, since the upper clamp 9 and the lower clamp 11 are both open, the wire 3 is pulled out more than necessary, and at E, the loop L hangs down as shown by the broken line, and there is a risk that it will shoot with the pellet 18. It was hot.

[Purpose of the invention]

The present invention provides a wire bonding device which prevents the wire from being drawn out excessively and shooting into the pellet when the wire is bonded to a pellet and then bonded to a lead frame.

[Summary of the invention]

Close the upper clamp, lower the bonding tool, bring the ball at the tip of the wire into close contact with the tip of the bonding tool, bond the ball to the pellet of the semiconductor device, then raise the bonding tool, then lower it again to bond the wire to the lead frame. At the same time as the upper clamp is closed, the upper clamp is raised by a drive source separate from the bonding tool, thereby preventing the wire from being fed out more than necessary and eliminating the occurrence of slack in the wire when the bonding tool is raised again. This is designed to prevent accidental contact between the wire and the pellet.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 to 7, in which the same components as in FIG. 1 are given the same reference numerals. In the figure, 20 is an upper clamp, and all the constituent parts other than this upper clamp 20 are the same as those in FIG. 1, so a description thereof will be omitted. Upper clamp 2
The wire 3 is clamped by a pair of clamp members 21a and 21b. One of these clamp members 21a, 21a is directly attached to the bracket 22, and the other one is bonded to the leaf spring 23, for example, with an adhesive, and then fixed to the bracket 22 with screws 24, 24. In addition, in order to apply a clamping force for clamping the wire 3 to the clamp members 21a, 21a, a spring post 25 is screwed onto the bracket 22 through the leaf spring 23, and the head of the spring post 25 and the leaf spring 23 are connected to each other. A compression spring 26 is installed between the upper surface and the upper surface. In addition, the above bracket 2
2, levers 27 and 28 having pins 27a and 28a implanted at their ends so as to face each other are rotatably supported on a rotating shaft 29. These levers 2
7 and 28 are L-shaped mounting brackets 3 attached to the bracket 22.
Solenoids 31 and 3 installed through 0
2 to swing around the rotation axis 29,
The plate spring 23 is actuated via the pins 27a and 28a to open and close the clamp members 21a and 21a,
It is adapted to clamp and release the wire 3. That is, the solenoids 31 and 32 are always energized, and when they are turned off, the clamp members 21a and 21a are activated by the elastic force of the coil springs 33 and 34 or the compression spring 26, which returns the levers 27 and 28 to their initial positions.
is starting to close. When the solenoids 31 and 32 are energized at the same time, the lever 27 moves in the direction of releasing the leaf spring 23, and the lever 28 does not operate against the leaf spring 23. Then, when the solenoid 31 is turned off, the lever 27 is returned by the coil spring 33, and the leaf spring 23 is pressed by the compression spring 26 to close the clamp members 21a and 21a and close the wire 3.
It is designed to be clamped. When the solenoid 32 is turned off, the lever 28 is returned by the coil spring 34, presses the leaf spring 23, closes the clamp members 21a, and closes the wire 3.
It is designed to be clamped. By the way, the elastic force of the compression spring 26 is expressed by the coil spring 33.
and 34 weaker than that of solenoid 3
1 is turned off, the force with which the clamp members 21a, 21a clamp the wire 3 is weaker than when the solenoid 32 is turned off.

Next, the bracket 22 is rotatably supported by another bracket 35 on a rotating shaft 36, and the bracket 35 is fixed to the main body 1 via another bracket (not shown). A solenoid 37 is provided on the upper surface of the bracket 35, and when the solenoid 37 is turned on, the spindle 38 presses the upper surface bracket 22 on the lower surface of the bracket 35, causing the bracket 22 to rotate about the rotation shaft 36. The clamp member 2 provided at the tip of the bracket 22
1a and 21a are raised. Further, a bracket 22 is provided on the side of the solenoid 37 to resist the downward pressing force of the spindle 38.
A coil spring 39 biasing the bracket 35 toward the bracket 35 is supported at both ends by a spring post 40 provided on the bracket 35 and a spring post 41 provided on the bracket 22. Therefore, the solenoid 37 is energized,
When the bracket 22 is rotated clockwise to raise the clamp members 21a, 21a, the wire 3 is pulled upward, and then, when the solenoid 37 is turned off, the bracket 22 is rotated counterclockwise.

The operation of this invention configured as described above is explained in the eighth section.
This will be explained based on the diagram. A shows the state before the start of the bonding operation, and in this A, the upper clamp 20 is closed, but at this time the solenoid 31 is turned off and the lever 27 is actuated by the compression spring 26 to close the clamp members 21a, 21a, so the wire 3 The clamping force to clamp wire 3 is weak.
Since the frictional force is limited to the extent that the ball 17 at the tip of the wire 3 comes into close contact with the tip of the bonding tool 14, there is no possibility that the strength of the joint between the wire 3 and the ball 17 will decrease. After the ball 17 is crimped onto the pellet 18 at C in this way, the bonding tool 1 is attached as shown at D.
4 rises and moves laterally, and then descends again to bond the wire 3 to the lead frame 19. In order to remove the slack in the wire 3 and prevent it from short circuiting with the pellet 18, After the solenoid 32 is turned off, the lever 28 is actuated by the coil spring 34, and the wire 3 is strongly clamped by the clamp members 21a, 21a, the upper clamp 20 is raised as shown in _E3 . Upper clamp 2
0 is raised by turning on the solenoid 37 shown in FIG. 7 and rotating the bracket 22 clockwise. After removing the slack in the wire 3 in this way, the wire is bonded to the lead frame 19 as shown in F, and one cycle is completed through the steps G and H.

As in the above embodiment, the upper clamp 20 is connected to the wire 3
Since the wire 3 and the ball 17 can be clamped with a weak clamping force when bonding the ball 17 to the pellet 18, the strength of the joint between the wire 3 and the ball 17 is lower than before. It has the effect of not doing so.

In the above embodiments, a solenoid was used for the opening/closing and vertical movement of the clamp because the timing could be electrically controlled, but the invention is not limited to this; for example, a cam mechanism or a link mechanism may be used. It is also possible to operate in synchronization with the vertical movement of the bonding tool 14.

〔Effect of the invention〕

As explained above, in this invention, after bonding the wire to the pellet, when the bonding tool rises again and then begins to descend, the upper clamp is closed and simultaneously raised to pull up the wire, thereby reducing the slack in the wire. Since this is prevented, there is no risk of short circuits when bonding the wire to the lead frame, and quality can be improved.

[Brief explanation of drawings]

Fig. 1 is a side view of a conventional wire bonding device, Fig. 2 is an explanatory diagram of its operation, Figs. 3 to 7 show an embodiment of the present invention, and Fig. 3 shows a bracket supporting an upper clamp. FIG. 4 is a plan view showing the driving principle of the upper clamp, FIG. 5 is a plan view showing the operation of the solenoid in FIG. 4, FIG. 6 is a side view of FIG. FIG. 7 is a side view of the upper clamp, and FIG. 8 is a diagram illustrating its operation. 2... Wire feeding device, 3... Wire, 4... Wire guide, 11... Lower clamp, 14... Bonding tool, 17... Ball, 18... Pellet, 20
...Top clamp.

Claims (1)

[Claims] 1. A wire fed out from a wire feeding device is sequentially introduced into an upper clamp, a lower clamp and a bonding tool via a wire guide part, and the wire is bonded by the vertical movement of the bonding tool, wherein the wire is bonded by the upper clamp. A wire bonding apparatus characterized in that the wire bonding apparatus is capable of being raised and lowered independently of the raising and lowering movement of the bonding tool, and that when the bonding tool is lowered again, the upper clamp is closed and the wire is pulled up.