JPH0219965Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a wire bonding device for bonding workpieces such as IC chips with wire, and in particular, to a device that can maintain a constant wire loop height during bonding. The present invention relates to a bonding device equipped with a bonding device.

(Prior art) A plurality of IC chips arranged at equal intervals on a lead frame are automatically and intermittently transferred to a bonding station position one pitch at a time.
Wire bonding devices for bonding and connecting an IC chip and surrounding leads using wires are well known.

This type of device is equipped with a bonding tool that inserts and supports a wire for bonding and moves the wire to a bonding position. For example, as shown in FIG.
By applying ultrasonic vibration to the IC chip 3 and applying pressure, the wire 1 and the IC chip 3 are connected.
That is, a first bond connection is made. Next, move the bonding tool 2 upward (b in the same figure), move it horizontally from this position to a position directly above the lead 4 (c in the same figure), and then close the clamp 5 from this position to fix the wire 1. By lowering the bonding tool 2 and pressurizing the wire 1 by applying ultrasonic vibration to the lead 4, a bonding connection between the wire 1 and the lead 4, that is, a second bond connection is achieved (d in the figure). As a result, the wire connection between the IC chip 3 and the leads 4 is completed.

When connecting this IC chip 3 and lead 4,
A loop 6 is formed in the wire 1 as shown in FIG. 2d, and the height of this loop 6 is
The height h from the surface of the loop 6 to the highest point of the loop 6 needs to be maintained at an optimum constant height from the viewpoint of preventing short circuits and disconnections during resin molding. The height of this loop 6 mainly depends on the trajectory of the bonding tool 2 moving from the first bonding position to the second bonding position. For this reason, the control device that controls the movement of the bonding tool 2 is given an optimum setting value for the height of the loop 6, and a movement program for the bonding tool 2 to ensure this optimum setting value is provided to the control device. The bonding operation of the bonding tool 2 is performed by this movement program.

(Problem to be solved by the invention) However, if the bonding tool 2 does not want to operate according to the movement program due to changes in the feeding resistance of the wire 1 due to changes in the environment such as humidity, temperature, dust, etc., or for some other reason. However, there is a problem in that the height of loop 6 changes and deviates from the optimal setting value.Especially when automatic bonding is performed by unattended operation, the height of loop 6 changes.
This had the disadvantage that it was too late to notice changes in the height, resulting in a large number of defective products.

The present invention was developed in consideration of the above-mentioned conventional problems, and even if the wire loop height deviates from the optimum setting value due to environmental changes, this can be detected and corrected immediately. The present invention provides a wire bonding device that can always ensure a loop height equal to an optimal setting value.

(Means for solving the problems) In order to solve the above problems, the present invention is configured as follows. That is, the present invention includes a control device for controlling the movement of the bonding tool, and includes:
A wire bonding device that sequentially bonds workpieces that are transferred intermittently one by one using a wire, includes a loop detection device that detects the loop height of the bonded wire at a desired location, and a detection value of the loop detection device and a loop height setting value. and a comparison circuit for comparing the height of the wire loop and supplying the difference signal to the control device to adjust the height of the wire loop.

(Function) In the present invention having the above configuration, the movement of the bonding tool is controlled by the control device, and the movement of the bonding tool is controlled by the control device.
Bonding of the workpieces, which are intermittently transferred one by one, is performed one after another. The height of the wire loop at a desired location after bonding is completed is detected by a loop detection device, and a comparison circuit compares the detected value with a loop height setting value. If the height of the loop changes for some reason, a difference is generated between the detected value and the set value by comparison, and this difference signal is output from the comparison circuit to the control device. The controller modifies the operation of the bonding tool based on the difference signal to match the loop height of the bonded wire to the set point. In this way, the present invention allows the height of the wire loop to always match the set value, thereby making it possible to reliably prevent the production of defective products.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. In the description of this embodiment, the same members as those described in the conventional example are given the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a workpiece conveying device 7 is provided in the main body of the bonding device. This work transfer device 7 intermittently transfers a lead frame 8 on which a plurality of IC chips 3 as works are arranged at equal intervals to a bonding station one pitch at a time, that is, every interval at which the IC chips 3 are arranged. Bonding tool 2 is located opposite the bonding station.
The bonding tool 2 is connected to a bonding head 10 via a bonding arm 9. Bonding head 1
0 is attached to the first XY table 11,
By moving the first XY table 11 in the X and Y directions and moving the bonding head 10 itself in the vertical direction, the bonding head 10,
That is, the bonding tool 2 can be moved in three dimensions. The three-dimensional movement control of the bonding tool 2 is performed by a control device 12. That is, the control device 12 includes a set value for giving the optimum height of the loop 6 of the bonded wire 1, and a program for moving the bonding tool 2 from the above-described first bond connection position to the second bond connection position. is recorded, and by moving the bonding tool 2 according to this program, the height of the loop 6 of the wire 1 is made to match the set value.

However, if there is a change in the environment, there is a problem in that the height of the loop 6 of the wire 1 fluctuates even if the bonding tool 2 is operated according to the program, as described in the conventional example. In this embodiment, in order to eliminate this problem, the loop height of the IC chip 3 that has been bonded is detected, the difference from the set value is determined, and the operation of the bonding tool 2 is corrected based on this.

That is, in FIG. 1, a second XY table 13 is provided adjacent to the first XY table 11, and an autofocus device 14 is disposed on this second XY table 13 so as to be movable up and down. It is set up. A frame 15 is fixed to the autofocus device 14, and a loop detection camera 16 is attached to the tip of the frame 15. This loop detection camera 16 is opposed to the IC chip 3 on which bonding has been completed, and images the loop 6 of the wire 1. The focus of this image formation is determined by moving the autofocus device 14 up and down.

These second XY table 13, autofocus device 14, and detection camera 16 constitute a loop detection device 17 that detects the loop height. In this embodiment, a sensor (not shown) for detecting the vertical position of the autofocus device 14 is provided, and the vertical position of the autofocus device 14 corresponding to the imaging focal position of the detected loop 6 is determined. Detected. The detection signal of this sensor is then sent to the comparator circuit 18.
is supplied to

On the other hand, the comparison circuit 18 is given the vertical movement position of the autofocus device 14 corresponding to the set height of the loop 6 as a set value, and therefore, the set value and the detected value of the detection signal are A comparison is made by comparison circuit 18 and the difference signal is output to controller 12.

The control device 12 is provided with an arithmetic circuit,
Desired arithmetic processing is performed based on the difference signal from the comparison circuit 17, and the moving operation of the bonding tool 2 is modified. As a result, even if the height of the wire loop changes during bonding due to environmental changes, the change is immediately corrected.
It becomes possible to always maintain the height of the loop 6 at a constant value equal to the set value.

Note that in this embodiment, the autofocus device 14 and the loop detection camera 16 are
Since it is mounted on the XY table 13, it is possible to move the autofocus device 14 and the loop detection camera 16 to the position of any chip 3 that has completed bonding, and it is possible to freely select the loop 6 that you want to detect. can do.

Furthermore, as is well known, a large number of wires are bonded and connected to one IC chip 3, but detection of this loop 6 may be performed for all wires bonded to the IC chip 3. Often, representative wires may be selectively picked up from all the wires depending on the case, and an appropriate number of loops may be detected for each of the plurality of bonded IC chips 3.
The average value of each of these detections may be employed as the detection value, and in this way, various modes can be selected for detecting the loop height.

(Modification) In the above embodiment, the autofocus device 14 and the loop detection camera 16 are mounted on the second XY table 1.
The autofocus device 14 and the loop detection camera 16 are fixedly mounted on the body of the bonding device, etc., and the loop detection camera 16 is movable to the position of the loop 6 to be detected. It is also possible to detect the loop height of the IC chip 3 located at a constant distance from the station position.

(Effects of the invention) Since the invention is configured as described above,
Even if the loop height of the bonded wire changes from the set value due to some reason such as a change in the environment, the change is immediately detected and automatically repaired. As a result, it is possible to match the loop height of the bonded wire to the set value, which not only prevents the occurrence of a large number of defective products, but also effectively saves labor and stabilizes the bonding work. It is possible to perform highly reliable unmanned bonding operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 a to 2 d are diagrams illustrating the operation of wire bonding. 12... Control device, 13... Second XY table, 14... Auto focus device, 16... Loop detection camera, 17... Loop detection device, 18
...Comparison circuit.

Claims (1)

[Claims for Utility Model Registration] (1) In a wire bonding device that is equipped with a control device that controls the movement of a bonding tool and that sequentially bonds workpieces that are intermittently transferred one pitch at a time with a wire, a loop detection device that detects the loop height; and a comparison circuit that compares the detection value of the loop detection device with a loop height setting value and supplies the difference signal to the control device to adjust the height of the wire loop. A wire bonding device comprising: (2) Utility model registration claim No. 1, characterized in that the loop detection device consists of a loop detection camera that images the wire loop to be detected, and an autofocus device that focuses the image formed by the loop detection camera. ) The wire bonding device described in item 2. (3) The loop detection device includes a loop detection camera that images the wire loop to be detected, an autofocus device that focuses the image of the loop detection camera, and a loop detection camera and autofocus device that focuses on the loop position of the wire to be detected. 2. A wire bonding apparatus according to claim (1), characterized in that the wire bonding apparatus comprises a table that moves to and from the table.