JPH01251731A - Bonding wire inspection apparatus - Google Patents

Abstract

PURPOSE:To quickly detect the occurrence of an abnormality of a wire bonding operation by a method wherein, when an inclination of a bonding wire detected by a wire inclination detection means is of a prescribed value or higher, a stop signal of the wire bonding operation is sent. CONSTITUTION:An ITV camera 15 as an image sensing device is arranged directly above a lead frame 10 and an IC chip 11. A wire inspection apparatus 16 sends an image sensing instruction to the ITV camera 15 before and after a wire bonding operation. An inclination G of a bonding wire is detected from an image data obtained by picking up only an image data of the bonding wire from a difference in individual image data obtained by these image sensing operations. When the detected inclination G of the bonding wire is a prescribed value or higher, a stop signal is sent to a wire bonding apparatus 12. Accordingly, an abnormal inclination of the bonding wire can be detected quickly while a next wire bonding operation is in progress. When an abnormality occurs, the wire bonding operation can be stopped.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a bonding wire inspection device.

(Prior art) ASICs such as microprocessors and gate arrays
(Applicatlon 5 specific I
C, application specific integrated circuits) have a large number of electrodes. Therefore, in order to output electrical signals through each electrode (hereinafter referred to as a "ponding pad") of this A-SIC, the ASIC
Each bonding pad and the electrode 2 of the lead frame are connected by wire bonding. Note that the connected wire is referred to as a bonding wire 3. The number of bonding wires 3 wire-bonded in this way is about 180, and the distance between the wire connections is about 200 μm.

By the way, in such wire bonding, each bonding wire 3 is inspected to see if it is correctly connected.

This inspection is a two-dimensional method, and first, as shown in Fig. 27, the ASICI before wire bonding is
and the electrodes 2 of each lead frame to obtain image data, and then image data after wire bonding as shown in FIG. 28 is obtained. Then, by determining the difference between these image data, image data of only each bonding wire 3 as shown in FIG. 29 is obtained. According to this image data, each bonding wire 3 is accurately ASICI.
It is determined whether there is a connection between each bonding pad and the electrode 2 of each lead frame.

However, in such an inspection method, each bonding wire 3 is inspected after all wire bonding for one ASICI is completed, so that the bonding wire 3 may become tilted midway, for example, and may cause the bonding wire 3 adjacent to , it becomes difficult to quickly detect this wire bonding abnormality.

(Problems to be Solved by the Invention) As described above, it has been difficult to quickly detect wire bonding abnormalities when they occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a bonding wire inspection device that can quickly detect abnormalities in wire bonding when such abnormalities occur.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a bonding wire inspection apparatus for inspecting the loop shape of a bonding wire, including an imaging device disposed directly above the bonding wire, and an image pickup device using the imaging device. wire extraction means for obtaining image data of only the bonding wire from each image data before and after wire bonding; wire inclination detection means for detecting the inclination of the bonding wire from the image data obtained by the wire extraction means; This bonding wire inspection apparatus attempts to achieve the above object by including a stop means for sending out a wire bonding stop signal when the inclination of the bonding wire detected by the wire inclination detection means is equal to or greater than a predetermined value.

The present invention also provides a bonding wire inspection device for inspecting the loop shape of a bonding wire, which includes: a first imaging device disposed diagonally above the bonding wire; a second imaging device disposed directly above the bonding wire; Wire extraction means for obtaining image data of only the bonding wire from each image data before and after wire bonding captured by the first imaging device, and detecting the inclination of the bonding wire from the image data obtained by imaging by the second imaging device and bonding wire shape calculation means for calculating the side image data of the bonding wire from the image data obtained by the wire extraction means by correcting the wire inclination determined by the wire inclination detection means. This is a bonding wire inspection device that attempts to achieve the above object.

(Function) By providing such a means, the wire extracting means can obtain image data of only the bonding wire from each image data before and after wire bonding captured by the imaging device placed directly above the bonding wire. From this, the wire inclination detection means detects the inclination of the bonding wire. If the detected inclination of the bonding wire is greater than or equal to a predetermined value, the stop means sends out a wire bonding stop signal.

Further, by providing the above means, the wire extracting means obtains image data of only the bonding wire from each image data before and after wire bonding captured by the first imaging device disposed diagonally above the bonding wire, on the other hand,
The wire inclination detection means detects the inclination of the bonding wire from image data obtained by imaging with a second imaging device placed directly above the bonding wire. The bonding wire shape calculation means calculates side image data of the bonding wire from the image data obtained by the wire extraction means by correcting the wire inclination determined by the wire inclination detection means.

(Example) Hereinafter, a first example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a bonding wire inspection device.

In the same figure, 10 is a lead frame, and 11 is an AS
It is an IC chip such as an IC. Further, 12 is a bonding device, and its bonding tool 13 is a chip ICI.
It is located above I. Note that 14 is a wire.

Now, an ITV (industrial television) camera 15 as an imaging device is arranged directly above the lead frame 10 and the IC chip 11, that is, directly above the wire bonding. Further, 16 is a wire inspection device, and a first image memory 17 and a second image memory 18 are connected to this device.

Thus, the image signal output from the ITV camera 15 is converted into a digital image signal by an A/D (analog/digital) converter 19 and stored in the first or second image memory 17.
．． 18 and is selected and stored. Note that the wire inspection device 16 selects whether to store the image in the first or second image memories 17 and 18.

The wire inspection device 16 has the following functions. That is, (1) a wire extraction means that issues an imaging command to the TV camera 15 before and after wire bonding, and obtains image data of only the bonding wire from each image data obtained by these imaging; wire inclination detection means for detecting the inclination of the bonding wire from the image data obtained; and a wire inclination detection means for sending a stop signal to the wire bonding apparatus 12 when the inclination of the bonding wire detected by the wire inclination detection means is equal to or greater than a predetermined value. This is a function with a stopping means. Note that a display device 20 is connected to this wire inspection device 16.

Next, the operation of the apparatus constructed as described above will be explained according to the inspection flowchart shown in FIG. First, step sl
The number of bonding wires for wire bonding is set in . Then, when the wire frame 10 and the IC chip 11 are set in the predetermined positions, the next step S
2, the wire inspection device 16 issues an imaging command to the ITV camera 15. Upon receiving this imaging command, the ITV
The camera 15 images the lead frame 10 and the IC chip 11 before wire bonding and outputs the image signal. This image signal is converted into a digital image signal by the A/D converter 19 and is first stored in the first image memory 17 as image data.

Next, the wire inspection device 16 issues a work start command to the wire bonding device 12 in step S3, and upon receiving this command, the wire bonding device 12 inspects the bonding pad 1a of the IC chip 1 and the lead frame as shown in FIG. First, a first connection is made between the wires 14 and the 10 electrodes 10a. As a result, bonding wire 21 is formed. When this wire bonding is completed, the wire inspection device 16 issues an imaging command to the ITV camera 15 again in step S4. Thus, the TV camera 15 outputs an image signal after wire bonding as shown in FIG. This image signal is then converted into a digital image signal and stored in the second image memory 18. In this way, the image data is
Once stored in the image memory 18, the bonding wire 21 is extracted by calculating the difference between the first image and the second image in step S5. This extraction process is performed by determining from the difference between the image data before wire bonding shown in FIG. 3 and the image data after wire bonding shown in FIG. The image data obtained by this extraction process consists of only the bonding wire 21, as shown in FIG. When this extraction process is completed, the image data stored in the first image memory 17 is erased and the image data stored in the second image memory 18 is transferred to the first image memory 17 in step s6.

In step s7, the wire is confirmed by the above-mentioned bonding, and if it is determined that there is a wire, step s
8, the deviation from the reference line E as shown in FIG. 4, that is, the inclination of the bonding wire 21, is calculated. Therefore, this slope is calculated as follows. That is, the seventh
As shown in the figure, the coordinates of the bonding butt of the IC chip 11 are (xl).

yl), and the coordinates of the electrode 10a of the lead frame 10 are (x2. y2). Then, assuming that the line connecting these coordinates is Ql, the angle θ at which it intersects with the in Q2 parallel to the X axis is determined. Note that this angle θ is θ-tan'
(y2-yl) / (x2-xi) ...(
It can be found from 1). Next, coordinate (xl) by this angle θ.

yl) as the center, and the line Q1 is made parallel to the X axis as shown in FIG. Here, in the data obtained in this way, coordinates (xi, yl) and coordinates (x2
=, y2-) in the y-axis direction as XS,
Let it be e. Then, a center line F of the width of the bonding wire 21 is determined in the range from XS to xe.

When the center line F is determined in this way, from XS to xe
Divide into multiple parts within the range of al.

a2..., and divide these dividing points a1. a2...
Find the distance between the center line F and the X-axis. Therefore, these distances correspond to the slope G of the bonding wire 21.
The value is .

When the value of the slope G of the bonding wire 21 is determined in this way, the wire inspection device 16 moves to the next step s9 and determines whether the value of the slope G exceeds a predetermined value.
If it is less than the predetermined value, it is determined in step slO whether the inspection of all the bonding wires has been completed, and if the inspection has not been completed, the wire inspection device 16
An imaging command is issued in step 5, and bonding is performed in step sll. At this time, the captured image is after the bonding wire 22 is connected as shown in FIG. 9, and this image data is stored in the second image memory 18, and an image difference is calculated in step s12. .

By the way, if it is determined in step s9 that the value of the slope G of the bonding wire 21 exceeds a predetermined value, the wire inspection device 16 moves to step s13 and issues a stop operation to stop the wire bonding device 12. Send a command. As a result, the wire bonding device 12 stops the bonding operation while wire bonding the bonding wire 23 is being performed. Note that step s13 also issues the above-mentioned stop operation when it is determined in step s7 that there is no wire.

In this way, in the first embodiment, the bonding wires 22, 23, .・The inclination of the bonding wires 22, 23... is detected by obtaining the image data of the bonding wires 22, 23...
・A wire bonding stop signal is sent when the inclination of - can be detected quickly, which allows the bonding wire work to be stopped when an abnormality occurs. Therefore, the efficiency of wire bonding work can be greatly improved.

Next, a second embodiment of the present invention will be described. In addition, the first
Components that are the same as those in the figures are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 11 is a configuration diagram of a bonding wire inspection device. There is an X above the lead frame 10 and the IC chip 10.
A Yθ table 30 is arranged, and this XYθ table 30
A first ITV camera 31 and a 21st TV camera 32 are attached to the.

The ITV camera 31 takes an image of the bonding wire from diagonally above, and its angle is fixed at ψ. Further, the second ITV camera 32 takes images of the lead frame 10 and the IC chip 11 from directly above. In addition,
The first and 21st TV cameras 31 and 32 are moved stepwise by the XYθ table 30 for each bonding and are placed at the above positions. and,
The image signal output from the first ITV camera 31 is A/D
It is converted into a digital image signal by the converter 33 and stored as image data in the third image memory 34, and is also transmitted to the 21st TV.
The image signal output from the camera 32 is converted into a digital image signal by an A/D converter 35 and stored as image data in a fourth image memory 36.

These third and fourth image memories 34 and 36 are connected to the wire inspection device 38 via the camera control device 37, respectively.
is connected to.

This wire inspection device 38 has the function of determining the loop shape of the bonding wire, and has the following functions. That is, wire extraction means obtains image data of only the bonding wire from each image data before and after wire bonding taken by the first ITV camera 31, and a wire extraction means obtains image data of only the bonding wire from the image data taken by the 21st TV camera 32. wire inclination detection means for detecting the wire inclination; and bonding wire shape calculation means for calculating the side image data of the bonding wire from the image data obtained by the wire extraction means by correcting the wire inclination determined by the wire inclination detection means. be.

The wire bonding control device 39 sends work control signals to the wire bonding device 12 and also sends and receives operation timing signals to and from the wire inspection device 38.

Next, the operation of the apparatus constructed as described above will be explained according to the inspection flowchart shown in FIG. First, step e
The number of bonding wires for wire bonding is set in l. And wire frame 10 and IC
When the chip 11 is set in a predetermined position, the wire inspection device 38 controls the camera control device 37 in the next step e2.
An imaging command for the 11th TV camera 31 is issued to the camera. In response to this imaging command, the first ITV camera 31 images the lead frame 10 and IC chip 11 before wire bonding and outputs the image signal.

This image signal is converted into a digital image signal by the A/D converter 33 and is first stored in the third image memory 34 as image data.
is stored in the first area of . Next, the wire inspection device 38 issues a work start command to the wire bonding control device 39 in step e3, and upon receiving this command, the wire bonding control device 39
Sends a work start control signal to With this, the 13th
As shown in the figure, the bonding butt 1 of the IC chip 10
0a and the electrode 10a of the lead frame 10 are connected with a wire 14. As a result, the bonding wire 40
is formed. When this wire bonding is completed, the wire inspection device 38 issues an imaging command to the first ITV camera 31 and the 21st TV camera 32 again in step e4. However, the first ITV camera 3
1 outputs the image signal after wire bonding shown in FIG. 13, and the 21st TV camera 32 images the wire bonding 40 from directly above and outputs the image signal. The image signal from the 11th TV camera 31 is converted into a digital image signal and stored in the second area of the third image memory 34, and the image signal from the 21st TV camera 32 is converted into a digital image signal and stored in the 4th image memory. The image is stored in the image memory 36.

When the image data is stored in this way, the wire inspection device 3
8 issues a next work start command to the wire bonding control device 39 in step e5, and then extracts the bonding wire 40 in step e6. This extraction process is performed by calculating from the difference between the image data before wire bonding stored in the third image memory 34 and the image data after wire bonding shown in FIG.

The image data obtained by this extraction process consists of only the bonding wire 40, as shown in FIG. When this extraction process is completed, the image data stored in the first area of the third image memory 34 is erased and the image data stored in the second area of the third image memory 34 is erased in step e7. It is moved to the first area.

Next, the wire inspection device 38 calculates the three-dimensional shape of the bonding wire 40 in step e8.

That is, the center line of the bonding wire is determined from the image data shown in FIG. 14, and the IC is connected as shown in FIG.
Let S be the position of the bonding pad of the chip 11, and W be the position of the electrode of the lead frame 10. Then, these positions S to W are divided into, for example, nine parts, and the height hl of the bonding wire 40 at these dividing points is hl, H2 when the bonding wire 40 is viewed diagonally from above.
...Find H8.

Next, from these heights hl, H2...H8, the heights Hl, H2... when the bonding wire 40 is viewed from the side.
・Convert to H8. Conversion to these heights Hl, H2...H8 is as follows: Hn -hn (1/cosψ) (n-1~
8)...(2) is obtained. FIG. 16 shows data obtained when the bonding wire 40 is viewed from the side, determined by these heights Hn.

Here, the above equation (2) will be explained with reference to the schematic diagram of FIG. 17. ΔABC and ΔADC are similar to each other. Therefore, ψ−ψ′ φ−φ′. As a result, 1(n'cos ψ--hn) is obtained, and the above equation (2) can be obtained from this equation.

Next, the wire inspection device 38 determines the inclination of the bonding wire 40 from the image of the bonding wire 40 seen from directly above, which is stored in the fourth image memory 36 . Incidentally, since the inclination of the bonding wire 40 is determined by the same method as the inclination determined in the first embodiment, a description of the method of detection will be omitted. Here, this slope is ±R1 The average value of height Hn is H
a, the correction value Δψ is Δψ−5 in−1 (±R/Ha)−(3) due to the slope ±R with respect to the height Hn of the bonding wire 40. Incidentally, the slope ±R is defined as "+" if the bonding wire 40 is tilted downward in the drawing, and "-" if it is tilted upward.
”. Therefore, by substituting this equation (3) into the above equation (2), height data of the bonding wire 40 that takes into account the inclination of the bonding wire 40 can be obtained. Note that if the bonding wire 40 is tilted toward the 11th TV camera 31 due to the correction by Δψ, the 1st
The inclination angle ψ of the 1st TV camera 31 is made smaller, and when the bonding wire 40 is inclined to the side opposite to the 1st ITV camera 31 side, the inclination angle ψ of the 11th TV camera 31 is increased. FIG. 18 shows data obtained by the above conversion when the bonding wire 40 is viewed from the side.

Next, in step e9, the wire inspection device 38
) The height Hn of the bonding wire 40 obtained from the formula
The quality of the shape of the bonding wire 40 is determined from this.

There are a plurality of determinations as shown in FIGS. 20 to 26. Fig. 20 shows the broken state of the wire, which can be determined from the data. The next figure, FIG. 21, shows the curl amount, which is as described above and will not be explained here. FIG. 22 shows a short-circuit state between wires, and by comparing the previous wire coordinate value and the current wire coordinate value, if the coordinates are the same or are closer than a certain value, it is determined that the wire is defective. Further, the next figure 23 shows an under loop, which is also the same as above and will not be explained here. FIG. 24 shows the insufficient height of the wire and the rise angle of inclination, both of which are compared with fixed values to determine whether the wire is defective. FIG. 25 shows an edge touch state, which is considered defective if the wire touches the edge of the surrounding frame or pellet. Figure 2B shows no wires;
If there is no wire data after bonding, it is considered defective.

Note that the shape of the bonding wire 40 may be determined using other methods.

If the shape of the bonding wire 40 is determined to be normal, the process moves to step elo and it is determined whether the wire bonding instructed in step e5 has been completed.

Then, when wire bonding is completed, step a
At 11, an imaging command for the ITV camera 31 is issued. Then, after determining whether all the bonding wires are connected in step c12, the process returns to step e5.

However, if it is determined in step e9 that the shape of the bonding wire 40 is defective, the wire inspection device 38 moves to step e13 and sends a stop command to the wire bonding control device 39. As a result,
The wire bonding device 12 stops its work in the middle of the next wire bonding.

In this way, in the second embodiment, the first ITV camera 31 is arranged diagonally above the bonding wire 40.
Since image data of only the bonding wire 40 is obtained from each image data before and after wire bonding taken in , side image data of the bonding wire 40 is obtained by correcting the inclination of the bonding wire 40.
Each time one bonding wire is bonded, for example every 0.5 to 0.2 seconds, the three-dimensional shape of the bonding wire 40 can be recognized and the quality of the shape can be determined. Moreover, since the shape of the bonding wire 40 is three-dimensional and the inclination is corrected, the shape of the bonding wire 40 can be accurately recognized. Then, the quality of the shape of the bonding wire 40 can be determined using various types of determination methods such as under-loop determination. Therefore, the bonding wire 40 can be inspected with high precision and at high speed.

Note that the present invention is not limited to the first and second embodiments described above, and may be modified without departing from the spirit thereof.

For example, the number of divisions when determining the slope in the first embodiment or the number of divisions when determining the height in the second embodiment may be any number of divisions.

It is possible to provide a bonding wire inspection device that can quickly detect bonding abnormalities when they occur.

[Brief explanation of the drawing]

1 to 1O are diagrams for explaining a first embodiment of a bonding wire inspection device according to the present invention,
Figure 1 is a configuration diagram, Figure 2 is an inspection flow chart, Figures 3 to 5
The figure shows the wire bonding state, Figure 6 is a diagram to explain the wire extraction action, Figures 7 and 8 are diagrams to explain the tilt detection action, and Figures 9 and 10 are as follows. Figures 11 to 1 showing wire 7 bonding of
FIG. 9 is a diagram for explaining the second embodiment of the present invention, FIG. 11 is a configuration diagram, FIG. 12 is an inspection flow chart, FIG. 13 and the third diagram, and FIGS. 18 and 19 are A diagram showing data when the bonding wire is viewed from the side, FIGS. 20 to 26 are diagrams for explaining determination of the bonding wire shape, and FIGS. 27 to 29 are diagrams for explaining the prior art. It is. 10...Lead frame, 11...IC chip, 1
2... Wire bonding device, 15... ITV camera, 16... Wire inspection device, 17... First image memory, 18... Second image memory, 30... XY child table 31. ...11th TV camera, 32-...2nd ITV camera, 34...3rd image memory, 36...
・Second image memory, 38...Wire inspection device, 39.
...Wire bonding control device. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 (a) (b) (c) 20th:
, :L: Fig. 21 Fig. 22 Fig. 23 Vi (a) (b) Fig. 24 Fig. 25 m 26 Fig. 27 Fig. 28 Fig. 29

Claims (2)

[Claims] (1) In a bonding wire inspection device that inspects the loop shape of a bonding wire, an imaging device placed directly above the bonding wire and image data before and after wire bonding captured by this imaging device are used to detect the bonding wire. wire extraction means for obtaining image data of only the wire; wire tilt detection means for detecting the tilt of the bonding wire from the image data obtained by the wire extraction means; and wire tilt detection means for detecting the tilt of the bonding wire from the image data obtained by the wire extraction means; 1. A bonding wire inspection device comprising: stop means for sending out a wire bonding stop signal when the slope is greater than or equal to a predetermined value. (2) A bonding wire inspection device that inspects the loop shape of a bonding wire, including a first imaging device disposed diagonally above the bonding wire, a second imaging device disposed directly above the bonding wire, and a second imaging device disposed directly above the bonding wire; wire extraction means for obtaining image data of only the bonding wire from image data before and after wire bonding captured by the first imaging device; a wire inclination detection means for detecting an inclination; and a bonding wire obtained by correcting the inclination of the wire obtained by the wire inclination detection means using side image data of the bonding wire from the image data obtained by the wire extraction means. A bonding wire inspection device characterized by comprising shape calculation means.