JPS6313344B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wire bonding method.

In the assembly of semiconductor devices, ICs, etc., as shown in FIG. 1, each electrode (first bonding pad) 2 of a circuit element 1 made of a semiconductor pellet
There is a wire bonding operation in which the wire 5 and the tip (second bonding position) 4 of the lead 3 extending around the pellet 1 are connected with a wire 5 such as a gold wire or an aluminum wire. This wire bonding work is carried out using many different types of wire bonders, such as nail head wire bonders and ultrasonic wire bonders. For example, in the case of ultrasonic wire bonders,
After a workpiece having a pellet and a lead is placed and fixed on a rotary table, the wedge and pellet are aligned and the wedge is operated. The wedge is moved by a cam rotated by a constant speed motor, as shown in FIG. That is, at T _1, the pellet descends at a high speed, and at T _2, it changes to a lower velocity slightly above the pellet and continues to descend, and from T ₃ to
At _T4 , the wedge is vibrated to bond one end of the wire to the pellet electrode (first bonding pad). After that, it rises again between T ₄ and _{T 5} to prepare for the next second bonding. At T ₅ to _{T 6} , the bonding tool is moved in a plane until T ₆
Sometimes a bonding tool is located directly above the second bonding location at the inner end of the lead. So again
At T ₆ , the bonding tool descends at a fast speed, and at T ₇ , slightly above the lead, it descends again at a slower speed, and at T ₈ to _{T 9} , the wedge is vibrated to fix a portion of the wire to the lead. . Thereafter, the wedge rises and returns to its original height at _T10 , completing one cycle of operation. Also, T ₀
Between T1 and _T1 , the bonding tool moves in a plane, and the rotary table also rotates to bring the bonding tool onto the pellet electrode.

By the way, the vertical movement of the bonding tool is performed by a cam that is rotated by a motor that rotates at a constant speed, and has the characteristics shown in Figure 2. ) Furthermore, as the number of electrodes increases, the maximum distance between the electrode and the inner end of the lead increases, and even in the same semiconductor device, there is a large difference between the shortest and longest bonding distance l. . Furthermore, if the plane movement speed of the bonding tool is too fast, large vibrations will occur, which will have a negative effect on positioning and wire bonding, so the maximum speed is determined by itself. Therefore, if the time required for the bonding tool to rise and fall is determined according to the longest bonding distance, this time will be determined by the rotation of the cam that is rotated by the motor that moves the bonding tool up and down. Therefore, it is constant regardless of the bonding distance. Therefore, for short bonding distances,
A long waiting time occurs between the completion of the plane movement of the bonding tool and the start of its descent, which is not efficient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a new device that reduces the cost of wire bonding work by efficiently operating a bonding tool.

The bonding tool that holds the wire protruding from the lower end is moved up and down, and the bonding tool is sequentially moved between the first bonding position group and the second bonding position group to connect each first bonding position and the corresponding second bonding position. In a wire bonding method in which positions are connected using wires, if the plane movement distance from each first bonding position to the corresponding second bonding position is long, the time from when the bonding tool rises to when it descends becomes longer. In addition, when the plane movement distance is short, wire bonding is performed by shortening the time from when the bonding tool rises to when it descends, and defining the operation of the bonding tool according to the length of the plane movement distance. This is a characteristic feature.

For example, the motor that moves the bonding tool up and down can be switched between high speed and low speed in advance, and the high speed rotation and low speed rotation can be used depending on the length of the bonding tool's planar movement distance.
Alternatively, they can be used in combination to reduce the waiting time of the bonding tool during wire bonding.

Next, the wire bonding method of the present invention will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a diagram showing the movement of the bonding tool. To explain this briefly, T ₀ ~
At T ₁ (T ₈ to _{T 1} ′), wait for the completion of the plane movement of the bonding tool, and at T ₁ to _{T 4} (T ₁ ′ to _{T 4} ′), bond the pellet to the electrode, and then from T ₄ to _{T 5} ( T ₄ ′～
At T ₅ ′), the completion of movement of the bonding tool onto the lead is waited for, and from T ₅ to _{T 8} (T ₅ ′ to _{T 8} ′), bonding to the inner end of the lead is performed. In the figure, L and P indicate the heights of the top surfaces of the leads and pellets, respectively.
In this movement of the bonding tool,
The bonding operation to the pellet and lead is similar to the conventional movement shown in FIG. ₀ ~ _{T 1} , T ₄ ~ T ₅ , T ₈ ~ T ₁ ',
T ₄ ′ to _{T 5} ′ are not constant as in the past, but correspond to the length of the plane movement distance of the bonding tool; the longer the movement distance, the longer the above-mentioned time is, and the shorter the movement distance, the longer the time it takes to stay at a high position. becomes shorter.
As shown in Figure 4, this residence time is determined by setting the rotation of the motor that moves the bonding tool up and down in two stages, and if a long residence time is required, the high speed rotation time T ₄ ~ T _P (T _H ) shorten and slow time T _P ~ _{T 5}
It can be determined freely by lengthening the time of (T _L ). In other words, when the moving distance is long, the dwell time can be increased by lengthening the low rotation time of the motor that moves the bonding tool up and down.
Conversely, if the moving distance is short, the residence time can be shortened by increasing the high-speed rotation time of the motor. In addition, the distance of plane movement of the bonding tool is calculated by inputting each bonding position information and calculating each bonding position in recent automatic wire bonders. It is possible to easily calculate the value of T _H and T _L so that the waiting time of the bonding tool becomes zero. Therefore, the moving distance of the bonding tool is calculated and wire bonding is performed by automatically selecting high speed rotation or low speed rotation of the motor.

This method is one method for determining the high speed time (T _H ) and low speed time (T _L ) of the motor, but it also has the following aspects.

In other words, the motor is switched from high speed to low speed at the same time as the surface movement of the bonding tool starts, checking whether the parallel movement is completed, and switching from low speed to high _speed as soon as the parallel movement is completed. _L ) is determined.

In the former case, T _H is set in advance before the plane movement starts.
Since it is determined by calculating and T _L , it is the most efficient, but the control is complicated. On the other hand, the latter
Although it is less efficient than the former, it is easier to control. Practically speaking, the latter option is more effective.

According to the present invention, unnecessary waiting time for the bonding tool is eliminated, so that a series of wire bonding operations can be performed efficiently. Therefore,
It also improves productivity and reduces production costs. Further, since bonding is performed at a speed that does not adversely affect bonding during each operation time, it is possible to perform bonding with excellent quality and high reliability.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of pellets and leads showing the state of wire bonding in semiconductor device assembly, FIG. 2 is a cam diagram showing the movement of a conventional bonding tool, and FIG. 3 is a diagram of a wire bonding apparatus according to the present invention. FIG. 4 is a diagram showing the movement of the bonding tool according to the embodiment. Similarly, FIG. 4 is a diagram showing the driving state of the motor that moves the bonding tool up and down. 1... Circuit element (pellet), 2... First bonding pad (electrode), 3... Lead, 4...
Second bonding position, 5...wire.

Claims (1)

[Claims] 1 The bonding tool that holds the wire protruding from the lower end is moved up and down, and the bonding tool is sequentially moved between the first bonding position group and the second bonding position group to connect each first bonding position to the corresponding second bonding position. In a wire bonding method in which bonding positions are connected using wires, when the plane movement distance from each first bonding position to the corresponding second bonding position is long, the time required from when the bonding tool rises to when it descends is Along with making it longer,
When the plane movement distance is short, the wire bonding is performed while shortening the time from when the bonding tool rises to when it descends, and defining the operation of the bonding tool according to the length of the plane movement distance. Wire bonding method.