JPH0513539A - Wire bonding method - Google Patents

Abstract

PURPOSE:To stop the bonding operation so as to prevent the double bonding when the image is so recognized that it is applied with no bonding, or that it is applied with bonding by comparing the image corresponding to the specified lead with a reference pattern. CONSTITUTION:A binary image of the specified electrode in a semiconductor chip 8 to which any bonding has not been applied is registed in a storage section 10 as a reference pattern in advance. Prior to actual bonding, an electrode image on the chip 8 positioned on the bonding position is picked up by using a camera 6 and is binarized through an image processor 9. Then the image is judged, based on any pattern recognition, on whether or not bonding processing has been applied to the chip 8, through comparing the image with the reference pattern that has been registered in the section 10. In the case where the chip is judged that it has been applied with bonding processing, the bonding of the chip 8 is stopped so as to prevent the double bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method for connecting an electrode of a semiconductor chip and a lead of a lead frame with a conductive wire.

[0002]

2. Description of the Related Art In this type of wire bonding work, a lead frame on which a semiconductor chip is mounted is positioned at a bonding position in the previous step, and a conductive material is used between each electrode of the semiconductor chip and a lead by using a tool called a capillary. Connect with wires.

[0003]

In the bonding work, lead frames are supplied and stored using the same magazine. Therefore, due to the carelessness of the operator, the magazine containing the bonded lead frame may be set again on the supply side, which causes double bonding, which causes defective products. .

In the conventional bonding work, however, no measures have been taken against this set mistake.

An object of the present invention is to provide a wire bonding method capable of reliably preventing double bonding.

[0006]

According to the present invention, prior to bonding, an image of a portion to be bonded positioned at a bonding position is captured, and this image is used as a preset image without bonding or bonding. The feature is that the image is compared with the already-existing image.

[0007]

According to the present invention, prior to bonding, the image taken from the bonding site is compared with a preset image that has not been bonded or an image that has been bonded, and bonding has been performed. If no missing image is recognized, or if a bonded image is recognized, the bonding operation is stopped, thereby preventing double bonding.

[0008]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a wire bonding apparatus for carrying out the present invention, FIG. 2 is a diagram showing electrodes of a semiconductor chip which is not bonded, and FIG. It is a figure which shows the electrode of the semiconductor chip which exists. In the figure, reference numeral 1 is an XY table, and a bonding head 2 is mounted on the XY table 1. The bonding head 2 supports the bonding arm 3 swingably in the vertical direction, and a capillary 5 into which the conductive wire 4 can be inserted is attached to the tip of the bonding arm 3.

Reference numeral 6 denotes a camera fixed to the bonding head 2 for picking up an image of the lead frame 7 positioned at the bonding position and the semiconductor chip 8 mounted in the previous step. An image processing device 9 binarizes an image captured by the camera 6, and compares the binarized image with a reference pattern stored in a storage unit 10 described later by pattern matching. 10 is an image processing device 9 From 2
A storage unit 11 for storing the binarized image is a control device for controlling the image processing device 9, the bonding head 2, and the XY table 1.

Next, the operation will be described.

First, as a preparatory work, a lead frame 7 to which wire bonding is not applied is prepared, and one of the semiconductor chips 8 mounted thereon is positioned at the bonding position. Next, by moving the XY table 1, the position of the camera 6 is changed to the semiconductor chip 8 thereof.
The image is captured in accordance with the specific electrode 8a in (1) (see FIG. 2). In the case of this embodiment, the electrode 8a which is first bonded at the start of the bonding operation is set as a specific electrode. The image captured by the camera 6 is binarized by the image processing device 9, and the binarized image is registered in the storage unit 10 as a reference pattern.

In the actual bonding operation, first, the semiconductor chip 8 on the lead frame 7 positioned at the bonding position is discriminated as to whether or not it is bonded as follows. That is, first, from among the plurality of electrodes of the semiconductor chip 8 positioned at the bonding position, an image corresponding to the reference pattern registered in the storage unit 10, that is, in the present embodiment, bonding is first performed at the start of the bonding operation. The image of the applied electrode 8a is captured by the camera 6 in the same manner as the registration of the reference pattern. Then, the captured image is binarized by the image processing device 9. Then, the binarized image is further compared in the image processing device 9 with a reference pattern registered in advance in the storage unit 10 by pattern matching. At this time, as shown in FIG. 2, when the semiconductor chip 8 is not wire-bonded, the camera 6 has a predetermined matching rate between the binarized image based on the image captured this time and the reference pattern. Therefore, it can be recognized in the image processing apparatus.

However, as shown in FIG. 3, when the semiconductor chip 8 is already wire-bonded, the image of the wire 4 is also included in the binarized image based on the image captured by the camera 6 this time. Therefore, it does not have a predetermined matching rate with the reference pattern. Therefore, the pattern cannot be recognized in the image processing device 9.

Therefore, in the control device 11, when the image processing device 9 can recognize the pattern, it is determined that the semiconductor chip 8 is not wire-bonded, and the XY table 1 and the bonding head 2 are bonded. Send a start command to start normal bonding work. On the other hand, when the image processing device 9 cannot recognize the pattern, it determines that the semiconductor chip 8 has already been wire-bonded, sends a bonding operation stop command to the bonding head 2, and outputs an alarm (not shown). The device is designed to notify the operator.

According to the above-described embodiment, the pattern obtained from the semiconductor chip 8 positioned at the bonding position is compared with the reference pattern in the image processing device 9 before the bonding, and the semiconductor is detected according to the recognition result. It is determined whether or not the wire bonding is not applied to the chip 8. If it is determined that the bonding is completed, the bonding to the semiconductor chip 8 is stopped, so that the defective product due to the double bonding is generated. It can be surely prevented.

In the above embodiment, an image of a specific electrode on a semiconductor chip to which wire bonding has not been performed is registered in advance as a reference pattern, and prior to actual bonding, on a lead frame positioned at the bonding position. By comparing the image of the electrode of the semiconductor chip with the reference pattern, whether or not the bonding is completed can be determined. However,
An image of a wire-bonded electrode may be registered as a reference pattern, and if the pattern can be recognized, the semiconductor chip may be determined to be bonded. Further, instead of the electrode image of the semiconductor chip, an image of the bonding site on the lead may be registered as a reference pattern, and this reference pattern may be compared with the image captured from the lead.

Further, the determination as to whether or not the bonding has been completed may be performed before reaching the bonding position, for example, when the lead frame is at the standby position.

[0019]

According to the present invention, double bonding can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a wire bonding apparatus for carrying out the present invention.

FIG. 2 is a diagram showing electrodes of a semiconductor chip that is not bonded.

FIG. 3 is a diagram showing electrodes of a semiconductor chip to which bonding is applied.

[Explanation of symbols]

1 XY table 2 Bonding head 3 Bonding arm 4 wires 5 capillaries 6 cameras 7 lead frame 8 semiconductor chips 8a electrode 9 Image processing device 10 memory 11 Control device

Claims (2)

[Claims] 1. A wire bonding method for connecting an electrode of a semiconductor chip and a lead of a lead frame by using a conductive wire, wherein an image of a specific electrode or a specific lead, which is not bonded, is used as a reference pattern. Is stored in the storage means in advance and positioned at the bonding position prior to the actual bonding,
An electrode corresponding to the specific electrode in the semiconductor chip,
Alternatively, a wire bonding method is characterized in that an image of a lead corresponding to the specific lead in a lead frame is captured, and the captured image is compared with the reference pattern. 2. In a wire bonding method for connecting an electrode of a semiconductor chip and a lead of a lead frame by using a conductive wire, an image of a specific electrode or a specific lead that has been bonded is stored in advance as a reference pattern. Before the actual bonding, the image of the electrode corresponding to the specific electrode in the semiconductor chip or the lead corresponding to the specific lead in the lead frame, which is stored in the means, is captured, A wire bonding method, wherein the captured image is compared with the reference pattern.