JPH0468776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wire bonding apparatus for bonding a metal wire to a pellet in, for example, an IC assembly process.

[Technical background of the invention and its problems]

Wire bonding equipment, which is generally used for assembling integrated circuits, performs bonding by pressing a capillary into which a gold wire is inserted against a pad of a pellet, which is the first bonding point, and then moves the capillary in the vertical and XY directions to bond the wire. The wire is connected by repeatedly feeding out the wire, bonding it to the lead portion of the lead frame which is the second bonding point, and then raising the capillary and cutting the wire.

By the way, in the above-mentioned bonding operation, the bonding load and temperature when the capillary presses the pellet surface and press-bonds the gold ball formed at the tip of the wire are particularly important in determining the quality of the bonding.

However, in conventional wire bonding devices, the bonding load is set using the deformation of a spring. That is, as shown in FIG. 1, while the tool arm holder d is attached to the tool lifter b which is swingably supported on the rotation axis a via the leaf spring c, the gap between the tool lifter arm b and the tool arm holder d is A bonding load setting mechanism e was provided. That is, a spring hanging piece f is provided at the upper end of the tool lifter arm b, a spring hanging piece g is provided at the upper part of the tool arm holder d, and a tension spring h is installed between these spring hanging pieces f and g. , A pin position adjustment mechanism j was provided between these spring hanging pieces f and g to constantly adjust the position of the pin i by a mechanism not shown inside. An adjusting screw k is rotatably attached to this pin position adjusting mechanism j. Further, the tool arm holder d is provided with a tool arm l, and a capillary n is provided at the tip of the tool arm holder d so as to face the pellet m.

To set the bonding load on the capillary n using the conventional bonding load setting mechanism e configured as described above, the tip of the tool arm l is raised with the tension gauge o, and the displacement amount of the tool arm l and the tension gauge are A measurer measures the scale of o to determine the relationship between displacement and load, and then replaces or adjusts the tension spring h to provide a displacement corresponding to the load. For this reason, the accuracy is not good, and therefore, especially when the leaf spring c is replaced, it is not possible to set the same bonding load with the amount of sinking of the capillary n before replacement, and the troublesome measurement adjustment is repeated and it takes a long time. The disadvantage was that the equipment had to be stopped for a long time. Further, when applying pressure with the capillary n, the capillary n is bent at the portion of the leaf spring c, and since the capillary n does not contact the bonding surface perpendicularly, a displacement of the impression occurs, and the reliability of the crimped portion is sometimes lowered. Furthermore, in order to apply pressure over a wide range, it was necessary to replace the leaf spring c.

[Purpose of the invention]

This invention was made in view of the above circumstances, and its purpose is to detect the relative position of the tool lifter arm and the tool arm using a detector, and to control the pressing force of the tool arm using an electric current. Thus, it is an object of the present invention to provide a wire bonding device that can automatically set the bonding load easily and with high precision.

[Summary of the invention]

The present invention provides a tool lifter arm, a driving means for vertically moving the tool lifter arm, a tool arm provided on the tool lifter arm so as to be movable vertically and having a capillary at its tip, and a tool lifter arm provided on the tool lifter arm and having a capillary at its tip. A linear motor having a detector that detects the relative position of the lifter arm and the tool arm, and a moving coil that controls the relative position of the tool lifter arm and the tool arm based on a signal from the detector. It is in.

The tool lifter arm is driven by a driving means such as a linear motor, and the tool lifter arm is further equipped with a detector that detects the relative position with respect to the tool arm. A linear motor having a moving coil is controlled so that the gap between the tool arm and the tool arm is detected, and the driving means rotates the tool lifter arm and the tool arm to lower the capillary. When the capillary comes into contact with the pellet, this is detected by the detector, the driving means is stopped, and the linear motor is driven to push the capillary downward via the tool arm to bond it with a predetermined bonding load. It was designed to do this.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the accompanying drawings. 1 in FIG. 2 is an XY table.
A support base 3 having a rotating shaft 2 is provided on the front upper surface of the XY table 1. This support stand 3
A tool lifter arm 4 is pivotally attached to the rotating shaft 2 so as to be vertically movable. This tool lifter arm 4
A tool arm holder 6 is fixed to the tool arm holder 6 via a leaf spring, and a tool arm 7 is attached to the tool arm holder 6. A capillary 8 is provided at the tip of the tool arm 7 so as to face the pellet 9. Further, a linear motor 10 as a second drive source is provided between the tool lifter arm 4 and the tool arm 7. That is, this linear motor 10 has a yoke 12 fixed to a support arm 11 protruding from the upper surface of the tip side of the tool lifter arm 4, and a yoke 12 as shown in FIG.
It consists of a permanent magnet 13 provided at the top of the tool arm holder 6, and a moving coil 14 swingably provided at the upper part of the tool arm holder 6, so that a bonding load is applied to the capillary 8 via the tool arm 7. There is.

On the other hand, a linear motor 15 serving as a first drive source for driving the tool lifter arm 4 is provided on the upper center surface of the XY table 1 . This linear motor 15 has a permanent magnet 17 attached to a yoke 16, and a moving coil 18 is swingably provided on the lower surface of the rear end side of the tool lifter arm 4. The tool arm 7 is moved up and down by swinging the tool arm 4 up and down. An overcurrent type gap sensor 19 is provided at the tip of the tool lifter arm 4 to detect the relative position with respect to the tool arm 7, and a non-contact position sensor 19 is provided at the end to detect the position of the tool lifter arm 4. A container 20 is provided. A position detector control circuit 21 is connected to the non-contact position detector 20 via an A/D converter (not shown). This position detector control circuit 21 includes a linear motor drive circuit 2.
2 are connected. This linear motor drive circuit 22 is connected to the moving coil 18 of the linear motor 15. Therefore, the position detector control circuit 21 counts the position-related pulse signals from the non-contact position detector 20 and outputs a drive signal to the linear motor drive circuit 22 to control the linear motor 15, thereby controlling the tool lifter. The position of arm 4 is controlled.

The gap sensor 19 is connected to a bonding control circuit 24 via an A/D converter 23. This bonding control circuit 24 is connected to a position detector control circuit 21 that controls the linear motor 15 as the first drive source, and is also connected to a pressurizing linear motor drive circuit 25. The pressurizing linear motor drive circuit 25 further drives the linear motor 1 as the second drive source.
0 moving coil 14.

Next, a procedure for wire bonding using the wire bonding apparatus configured as described above will be explained. The gap between the tool arm 7 and the tool lifter arm 4 is detected by a gap sensor 19, and a bonding control circuit 24 pressurizes the linear motor 10 as a second drive source so that the gap becomes a specified value. Control via. As a result, the tool arm 7 and the tool lifter arm 4 are integrated in a servo-locked state and move up and down. When a capillary movement command is issued from the bonding control circuit 24 in such a state, a current command is output to the linear motor drive circuit 22 and the linear motor 1
A current flows to the moving coil 18 of No. 5, the tool lifter arm starts swinging, and at the same time, the capillary 8 moves. Whether or not the capillary 8 has come into contact with the pellet 9 can be determined by checking the output of the gap sensor 19 using the A/D.
When the converter 23 converts into digital data and the amount of change in the digital value exceeds a certain specified value, the bonding control circuit 24 makes a judgment, changes the control mode, and stops the linear motor 15. Thereafter, a current is applied to the moving coil 14 of the linear motor 10 so that the current and load change linearly as shown by the straight line A in FIG. 4, thereby pushing down the tool arm 7 and pressurizing the pellet 9 for bonding. Do this. Furthermore, bonding is performed by applying pressure to the lead frame side in the same way, and this process is repeated.

In the above embodiment, the overcurrent type gap sensor was used to detect the relative position between the tool lifter arm 4 and the tool arm 7.
The detection is not limited to this, and it may be detected by optical means.

Alternatively, the gap sensor may be mounted on the tool lifter arm to detect relative displacement with the tool arm holder 6 to perform the above control.

〔Effect of the invention〕

As explained above, in this invention, the tool lifter arm is driven by a driving means such as a linear motor, and the tool lifter arm is further equipped with a detector that detects the relative position with respect to the tool arm. The signal, that is, the gap between the tool lifter arm and the tool arm, is detected, and a linear motor with a moving coil is controlled so that the detected value becomes a specified value, and the tool lifter arm and the tool arm are rotated by the driving means. to lower the capillary. When the capillary comes into contact with the pellet, this is detected by the detector, the driving means is stopped, and the linear motor is driven to push the capillary downward via the tool arm to achieve a predetermined bonding load. Since the bonding is performed with a high precision, it is possible to easily set the bonding load. In addition, since the deformation of the leaf spring is extremely small when applying pressure, not only is it possible to prevent impressions caused by misalignment of the capillary, but also the bonding load can be set over a wide range because the pressing method uses the thrust of a moving coil. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a conventional bonding load setting mechanism, FIG. 2 is a side view showing an embodiment of the present invention, FIG. 3 is an enlarged side view showing the second driving source, and FIG. The figure is a graph diagram showing the relationship between the bonding load and the current applied to the moving coil of the linear motor in the present invention. 4...Tool lifter arm, 7...Tool arm,
8... Capillary, 10... Linear motor (second drive source), 15... Linear motor (first drive source), 1
9... Gap sensor, 24... Bonding control circuit.

Claims (1)

[Claims] 1 a tool lifter arm, a driving means for vertically moving the tool lifter arm, a tool arm provided on the tool lifter arm so as to be movable up and down and having a capillary at its tip; The present invention is characterized by comprising a detector that detects the relative position with respect to the tool arm, and a linear motor having a moving coil that controls the relative position of the tool lifter arm and the tool arm based on a signal from the detector. wire bonding equipment.