JPH0779113B2 - Wire bonding equipment - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a wire bonding method in a semiconductor device assembling process.

In the process of assembling a semiconductor device, there is a work of forming a gold wire in order to electrically connect an electrode on a pellet and an external lead, that is, a wire bonding process. In most conventional wire bonding apparatuses, a cam drives an arm to which a capillary is attached, the trajectory of the capillary is controlled by the shape of the cam, and the pressure during bonding is applied by a spring. According to such a method, when it is necessary to change the trajectory of the capillaries and the bonding pressure corresponding to each of the heterogeneous semiconductor devices, it is necessary to change the shape of the cam and the setting of the spring each time, and it is necessary for a long time. Needed adjustment. Further, in recent years, there has been a strong demand for speeding up of the bonding operation, but in the conventional structure, it has been difficult to speed up because of the problem of the ability of the arm to follow the cam. Especially after the capillary contacts the bonding pad,
Expect a variation in the height of the pellet.Because the arm is disengaged from the cam and the pressure is positively applied by the spring, the cam must be rotated to apply downward force to the capillary, so extra time is required. It will be.

The present invention eliminates the above-mentioned drawbacks and provides a novel apparatus capable of performing bonding in a short time.

According to the present invention, in a wire bonding apparatus having an arm for vertically moving a capillary and having a function of detecting the position and speed of the arm, a magnetic flux is generated in a gap of a magnetic circuit including a permanent magnet and a yoke. The arm is driven by an oscillating motor having a moving coil that is swingable in a plane at a right angle and is directly connected to the arm.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of an apparatus to which the present invention is applied, and FIG. 2 is a block diagram explaining its control unit. In FIG. 1, a swing arm 1 is swingable around a shaft 2 as indicated by an arrow in the figure. A capillary 3 is attached to one end of the swing arm 1 and a moving coil 4 is attached to the other end. The moving coil 4 is located in the air gap of the magnetic circuit 5 composed of the permanent magnet 51 and the yoke 52.
The arm 1 is driven by applying a current to the arm 1, and the position and speed of the arm 1 are detected by the position detector 6 and the speed detector 7 attached to the shaft 2, respectively. Capillary 3
Holds the gold wire 8 and presses the tip of the gold wire 8 against the bonding pad of the semiconductor pellet 9 for bonding. As is apparent from the figure, since the vertical movement of the capillary 3 is directly driven by the moving coil 4 and the magnetic circuit 5 without passing through a mechanical receding conversion mechanism such as a cam, mechanical vibration or the like does not occur and high speed operation is possible. It is easy to swing, and the up and down movement of the capillary 3 is controlled by controlling the current of the moving coil 4 while detecting the signals of the position detector 6 and the speed detector 7. Therefore, the degree of freedom for changing the operation is high. The bonding pressure can also be easily controlled by the current flowing through the moving coil 4.

Next, an example of the configuration of the control unit of the above bonding apparatus will be described with reference to FIG. In FIG. 2, 4 is a moving coil, 6 is a position detector, 7 is a speed detector, 10 is a speed command circuit that outputs a speed command signal according to a position signal from the position detector 6, and 11 is a speed command circuit 10. A comparison circuit that compares the speed command signal and the speed from the speed detector 7 and outputs a difference signal between the two signals, 12 is a pressure command circuit that outputs a predetermined bonding pressure signal, and 13 is a speed signal from the speed detector 7. A switching circuit for selecting and outputting a difference signal from the comparison circuit 11 or a bonding pressure signal from the pressure command circuit 12 in accordance with the above, and a driving circuit 14 for supplying a current proportional to the output signal from the switching circuit 13 to the moving coil 4. is there.

The speed command circuit 10 compares the speed command signal according to a speed profile set so that the capillary 3 can move in a short time in advance until the capillary 3 descends from above the pellet 9 to a predetermined height from the pellet 9. The difference signal output from the comparison circuit 11 is selected by the switching circuit 13, the moving coil 4 is driven via the drive circuit 14, and the capillary 3 operates according to the speed profile.

After the capillary 3 reaches a predetermined height, a low speed constant speed signal is output from the speed command circuit 10 and the capillary 3 descends at a low speed until it comes into contact with the pellet 9.
When the capillary 3 comes into contact with the pellet 9 and the output of the speed detector 7 becomes zero, the switching circuit 13 selects the signal from the pressure command circuit 12, and the moving coil 4 is driven by a constant current regardless of the speed and is constant on the pellet 9. Bonding pressure is applied.

By controlling as described above, the capillary 3
Since the pressure is applied from the point when the pad contacts the pad and the idle pressure is applied for the time required for bonding, the bonding operation can be performed in a shorter time than the conventional cam method. In addition, since the impact force and the bonding pressure at the time of contacting the pellet 9 are also controlled, defective bonding and cracking of the pellet can be prevented.

Further, since the above velocity profile, constant velocity signal, bonding pressure signal, etc. can all be electrically set, there is an advantage that pellets of different types can be easily changed and conditions can be set.

As described above, according to the present invention, there is no unnecessary mechanical vibration source and it is not necessary to further lower the capillary after contacting the pad, so that bonding can be performed at high speed and in a short time. In addition, since the contact speed between the capillary and the pellet and the bonding pressure can be controlled arbitrarily, stable bonding can be obtained, and since the operating conditions can be easily changed, it is easy to handle different types of pellets. A bonding device is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a bonding apparatus according to the present invention.

FIG. 2 is a block diagram showing an example of a control unit thereof.

[Explanation of symbols]

 1 Swing Arm 2 Axis 3 Capillary 4 Moving Coil 5 Magnetic Circuit 6 Position Detector 7 Speed Detector 8 Gold Wire 9 Pellet 10 Speed Command Circuit 11 Comparison Circuit 12 Pressure Command Circuit 13 Switching Circuit 14 Drive Circuit

Claims (1)

[Claims] 1. An arm for vertically moving a capillary,
In a wire bonding apparatus having a function of detecting the position and speed of the arm, a moving coil that is swingable in a plane perpendicular to a magnetic flux in a gap of a magnetic circuit including a permanent magnet and a yoke and is directly connected to the arm is provided. A wire bonding apparatus, characterized in that the arm is driven by an oscillating motor provided therein.