JPH0444331A - Wire bonding apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] As a conventional technique, for example, Japanese Patent Publication No. 62-43336
There is a wire bonding device as shown in the publication.

A conventional wire bonding device has a capillary at one end and a moving coil that can swing in a plane perpendicular to the magnetic flux within the gap of a magnetic circuit consisting of a permanent magnet and a yoke at the other end. A swinging arm that cooperates with a swinging motor to form a swinging motor, a position detector that detects a swinging angle of the swinging arm, and a speed detector that detects a swinging speed of the swinging arm. The swinging arm moves according to a predetermined speed profile until the capillary approaches a predetermined distance from the bonding pad of the semiconductor pellet while detecting the outputs of the position detector and the speed detector. movement, and after the capillary reaches the predetermined distance, the swinging arm approaches the bonding pad at a constant speed, and after the capillary contacts the bonding pad and the output of the speed detector becomes zero. The moving coil includes means for controlling the current of the moving coil so that a constant current flows through the moving coil.

Next, a conventional wire bonding apparatus will be described in detail with reference to the drawings.

FIG. 2 is a perspective view showing a conventional example.

A swinging arm 101 is swingable around an axis 102 in the direction of arrow A, and a capillary 103 is attached to one end of the arm 101, and a moving coil 104 is attached to the other end.

The moving coil 104 has a permanent magnet 151 and a yoke 15.
The arm 1
The position and speed of the arm 101 are detected by a position detector 106 and a speed detector 107, respectively, which are attached to the shaft 102. Capillary 103 is gold wire 1
8, and attach the tip of the gold wire 108 to the semiconductor bullet 10.
Press it onto the bonding pad No. 9 to bond.

Next, the operation of the conventional bonding apparatus will be explained with reference to FIG.

In the speed command circuit 110, the capillary 103 is connected to the pellet 10.
Until the capillary descends from above 9 to a predetermined height from the bellet 109, a speed command signal is output to the comparator circuit 111 according to a profile set so that the capillary can move in a short time, and the speed command signal is output from the comparator circuit 111. The difference signal is selected by the switching circuit 113 and the driving circuit 114
The moving coil 104 is driven through this, and the capillary 103 operates according to the profile.

After the capillary 103 reaches a predetermined height, the speed command circuit 110 outputs a low constant speed signal to prevent the capillary 103 from colliding with the bonding pad, and the capillary 10B descends at a low speed until it contacts the pellet 109. .

The capillary 103 contacts the pellet and the speed detection circuit 10
When the output of 7 becomes zero, the switching circuit 113 selects a signal from the pressure command circuit 112, applies a constant current to the moving coil 104, and applies a constant bonding pressure to the pellet 109.

Generally, the speed at which the capillary 103 contacts the bonding pad is very slow, so it takes a certain amount of time (for filtering, etc.) to detect whether it is moving at low speed or has zero speed. There is a slight time delay after the capillary 103 actually contacts the bonding pad until zero velocity is detected.

Therefore, even if the capillary 103 and the bonding pad come into contact, the capillary 103 tries to move at the speed commanded by the speed command circuit 110 during this time delay, so the capillary 103 can press the bonding pad with a large force. becomes.

For this reason, conventional wire bonding apparatuses use a method in which a limit is set on the voltage applied to the moving coil 104 to prevent excessive pressurization. That is, until the capillary 103 comes into contact with the bonding pad, the capillary 103 is only moved at a low constant speed, so the voltage applied to the moving coil 4 is very small except for the transition period at the time of switching.

Therefore, after a certain period of time (transient time), a limiter must be set to the voltage applied to the moving coil 104 so that a voltage higher than the minute voltage required to move the capillary 103 at a constant temperature at a low speed cannot be applied. For example, even if there is a slight delay in detecting zero velocity, the capillary 103 will not press the bonding pad with a large force.

[Problem to be solved by the invention]

In the conventional wire bonding device described above, a limiter is set on the voltage applied to the moving coil to prevent the bonding pad from being pressurized with excessive force when the capillary comes into contact with the bonding pad, so the movement of the capillary is limited. Therefore, it is difficult to dampen the capillary bounding and vibration that occur when the capillary contacts the bonding pad. If capillary bounding or vibration continues during the pressurization period, adhesion and under-pad cracks are likely to occur, but since the damping properties are poor, vibrations are likely to persist, and as a result, non-adhesion and under-pad cracks are likely to occur. Therefore, there was a drawback that bonding reliability was low.

[Means to solve the problem]

The wire bonding device of the present invention has a capillary through which a gold wire is passed at one end, and a moving coil that can swing within the gap of the magnetic circuit in a plane perpendicular to the magnetic flux at the other end, and cooperates with the magnetic circuit. a swinging arm constituting a swinging motor; a position detection means for detecting the swinging amount of the swinging arm; a speed detection means for detecting the swinging speed of the swinging arm; In the wire bonding apparatus, the output from the position detecting means and the speed detecting means remains constant until the capillary reaches a predetermined distance from the bonding pad of the semiconductor pellet. A voltage is applied to the moving coil while detecting a signal to move the swinging arm according to a predetermined profile, and after the capillary reaches the predetermined distance, the swinging arm approaches the bonding pad at a constant speed. A voltage is applied to the moving coil such that the voltage applied to the moving coil does not exceed a predetermined voltage only when the swinging arm moves in a direction approaching the bonding pad after a predetermined period of time has elapsed. means for controlling the voltage applied to the moving coil so that a constant current flows through the moving coil after the capillary contacts the bonding pad and the output of the speed detector becomes zero; It consists of:

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the trajectory generation circuit 10, the capillary 103 is a pellet 109.
Until the capillary 103 descends to a predetermined height from above to a predetermined height, a target trajectory set in advance so that the capillary 103 can move in a short time is outputted to the servo circuit 11.
A control signal output from the servo circuit 11 is selected by the switching circuit 13, and the moving coil 104 is driven via the drive circuit 14, so that the capillary 103 operates according to the target trajectory.

When the capillary 103 reaches a predetermined height, the trajectory generation circuit 10 outputs a target trajectory for moving at a constant low speed, and the capillary 3 moves the pellet 10 at a constant low speed.
Descend until it touches 9.

At this time, since the capillary 103 is only moved at a low constant speed, the voltage applied to the moving coil 4 is very small except for the transition period at the time of switching.

The limiter 18 has a predetermined transient time (the transient period at the time of switching is experimentally measured, and the time is slightly longer than that)
Only when the capillary 103 is moving in the direction approaching the pellet 109 (hereinafter, this direction is referred to as downward, and the opposite direction is referred to as upward), the voltage applied to the moving coil 104 is The voltage is limited so that it does not exceed a predetermined voltage (hereinafter referred to as limit voltage). The limit voltage is normally set to a voltage slightly higher than the minute voltage required to move the capillary 103 at a constant, slow speed.

When the capillary 103 contacts the pellet 109, the servo circuit 11 tries to move it at a constant speed even though the capillary 103 contacts the pellet 109 and cannot move at a constant speed.
Try to apply a large voltage to

However, when the capillary 103 moves downward, the limiter 16 moves, so only a small limit voltage is applied to the moving coil 104, and therefore the capillary 103 does not press the bonding pad with a large force.

On the other hand, if the capillary 103 moves upward due to bounding or vibration, the limiter 16 does not work, so a large restoring force is used to move the capillary 103 at a constant speed. As a result, the bounding and vibrations that occur are rapidly suppressed.

Thereafter, when the output of the speed detector 7 becomes zero, the switching circuit 13 selects a signal from the pressure command circuit 12, applies a constant current to the moving coil 104, and applies a constant bonding pressure to the pellet 109.

〔Effect of the invention〕

The wire bonding device of the present invention sets a limiter on the voltage applied to the moving coil only when the capillary is moving downward after a predetermined period of time after the capillary switches to a low constant speed movement. There is no need to apply excessive pressure, and therefore no extra pressure is applied when the capillary and bonding pad come into contact, resulting in the effect that stable bonding can be obtained.

Furthermore, since the limiter is not set when the capillary is moving upward, it has good damping performance against capillary bounding and vibration that occur when the capillary contacts the bonding pad. Generally, if capillary bounding or vibration continues during the period when the bonding pad is pressurized by the capillary, it is likely to cause non-adhesion or cracks under the pad.However, due to good damping properties, the vibrations do not persist, resulting in non-adhesion and cracks under the pad. It is difficult to cause

This lick has the effect of increasing the reliability of bonding.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a perspective view of a conventional example, and FIG. 3 is a block diagram of a conventional example. 10... Trajectory generation circuit, 11... Servo circuit, 12
112... Pressure command circuit, 13, 113... Switching circuit, 14.114... Drive circuit, 15... Rocking motor, 16... Limiter, 51, 151... Magnet, 52° 152... Yoke, 101... Swinging arm, 102... Shaft, 103... Capillary, 14...
・Moving coil, 105...Magnetic circuit, 106・
...Position detector, 107...Speed detector, 108...
-Gold wire, 109...Bellet, 110...Speed command circuit, 111...Comparison circuit.

Claims (1)

[Claims] It has a capillary with a gold wire passed through it at one end and a moving coil that can swing in a plane perpendicular to the magnetic flux within the air gap of the magnetic circuit at the other end, and cooperates with the magnetic circuit to form a swing type motor. a swinging arm, a position detection means for detecting the swinging amount of the swinging arm, a speed detection means for detecting the swinging speed of the swinging arm, and a current detection means for detecting the current applied to the moving coil. In the wire bonding apparatus, the moving coil is configured to detect output signals from the position detecting means and the speed detecting means until the capillary reaches a predetermined distance from the bonding pad of the semiconductor pellet. The moving coil is moved so that the swing arm approaches the bonding pad at a constant speed after the capillary reaches the predetermined distance. A voltage is applied to the moving coil, and a limiter is set so that the voltage applied to the moving coil does not exceed a predetermined voltage only when the swinging arm moves in a direction approaching the bonding pad after a predetermined time elapses. , further comprising means for controlling the voltage applied to the moving coil so that a constant current flows through the moving coil after the capillary contacts the bonding pad and the output of the speed detector becomes zero. wire bonding equipment.