JPH05854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire bonding method in a semiconductor device assembly process.

In the assembly process of semiconductor devices, there is a wire bonding process in which gold wire is stretched to electrically connect electrodes on the pellet to external leads. In most conventional wire bonding devices, a cam drives an arm to which a capillary is attached, the shape of the cam controls the trajectory of the capillary, and pressure during bonding is applied by a spring. According to such a method, when the trajectory of the capillary and the bonding pressure have to be changed to correspond to each different type of semiconductor device, it is necessary to change the cam shape and the spring settings each time.
It required a long period of adjustment. In recent years, there has been a strong demand for faster bonding operations, but with conventional structures, it has been difficult to increase the speed due to problems such as the ability of the arm to follow the cam. In particular, even after the capillary contacts the bonding pad, the arm is released from the cam and the cam is rotated until the spring force is applied to the capillary in a downward direction. Adding oak will take extra time.

The present invention eliminates the above-mentioned drawbacks and provides a new method that allows bonding to be performed in a short time.

In the present invention, when performing wire bonding to a bonding pad of a semiconductor pellet by vertically controlling a capillary attached to a swinging arm, the wire bonding is performed until the capillary approaches a predetermined distance from the bonding pad. After the swinging arm descends at a high speed and the capillary reaches the predetermined distance, the swinging arm approaches the bonding pad at a low speed, and the capillary contacts the bonding pad. is detected, and wire bonding is performed on the bonding pad with a predetermined pressure from the time of this detection.

The present invention relates to an arm having a capillary at one end and a moving coil at the other end, which cooperates with a magnetic circuit to form a swing motor, a position detector for detecting the swing angle of the arm, and a position detector for detecting the swing angle of the arm. This can be accomplished by a wire bonding device that is equipped with a speed detector that detects the swinging speed and can arbitrarily control the trajectory of the capillary and the bonding pressure by controlling the current of the moving coil while detecting the position and speed of the arm.

The present invention will be explained in detail below using the drawings. FIG. 1 is a perspective view of an apparatus to which the present invention is applied;
The figure is a block diagram explaining the control section. In FIG. 1, a swinging arm 1 can swing around an axis 2 as shown by the arrow in the figure, and a capillary 3 is attached to one end of the swinging 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 a permanent magnet 51 and a yoke 52, and by passing a current through the moving coil 4, the arm 1 is driven.
The position and velocity of are detected by a position detector 6 and a velocity detector 7 respectively attached to the shaft 2. The 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 clear from the figure, the vertical movement of the capillary 3 is directly driven by the moving coil 4 and the magnetic circuit 5 without going through a mechanical retraction conversion mechanism such as a cam, so there is no mechanical vibration, etc., and high-speed movement is possible. It is easy to swing, and the vertical movement of the capillary 3 is controlled by controlling the current of the moving coil 4 while detecting the signals from the position detector 6 and speed detector 7, so there is a high degree of freedom in changing the operation. 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 section of the bonding apparatus will be explained using FIG. 2. 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 the position signal from the position detector 6, and 11 is a speed command circuit 10. Speed command signal and speed detector 7
12 is a pressure command circuit that outputs a predetermined bonding pressure signal. 13 is a pressure command circuit that outputs a predetermined bonding pressure signal from the comparison circuit 11 in response to the speed signal from the speed detector 7. A switching circuit 14 selects and outputs a difference signal or a bonding pressure signal from the pressure command circuit 12; 14 is a switching circuit 1;
This is a drive circuit that causes a current proportional to the output signal from the moving coil 3 to flow through the moving coil 4.

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

When the capillary 3 reaches a predetermined height, a constant low speed signal is output from the speed command circuit 10, and the capillary 3 descends at a low speed until it contacts the pellet 9. When the capillary 3 contacts 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 with a constant current regardless of the speed. bonding pressure is applied.

By controlling as described above, pressure is applied from the moment the capillary 3 contacts the pad, and air pressure can be applied only for the time required for bonding, so the bonding operation can be performed in a shorter time than with the conventional cam method. It can be carried out. In addition, since the impact force and bonding pressure when contacting the pellet 9 are controlled, poor bonding and cracking of the pellet can be prevented.

In addition, the aforementioned speed profile, constant speed signal,
Since all bonding pressure signals etc. can be set electrically, there is an advantage that changes and conditions can be easily set for different types of pellets.

As explained above, according to the present invention, there is no unnecessary mechanical vibration source and there is no need to further lower the capillary after contacting the pad, so bonding can be performed at high speed and in a short time. Also,
This wire bonding method has the following advantages: stable bonding can be obtained because the contact speed between the capillary and pellet and the bonding pressure can be controlled arbitrarily, and the operating conditions can be easily changed, making it easy to adapt to different types of pellets. is obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a bonding apparatus to which the present invention is applied, and FIG. 2 is a block diagram showing an example of a control section thereof. In the figure, 1 is a swing arm, 2 is a shaft, 3 is a capillary, 4 is a moving coil, 5 is a magnetic circuit, 6 is a position detector, 7 is a speed detector, 8 is a gold wire, 9 is a pellet, and 10 is a 11 is a comparison circuit, 12 is a pressure command circuit, 13 is a switching circuit, and 14 is a drive circuit.

Claims (1)

[Claims] 1. In a method of wire bonding to a bonding pad of a semiconductor pellet by controlling a capillary provided at the end of a swinging arm, the wire bonding is performed at high speed until the capillary approaches the bonding pad at a predetermined distance. After the swing arm is lowered and the capillary reaches the predetermined distance, the swing arm approaches the bonding pad at a low speed, and it is detected that the capillary has contacted the bonding pad. A wire bonding method characterized in that, from the time of this detection, wire bonding is performed on the bonding pad with a predetermined pressing force.