JPH0817858A - Electrode pad position detecting method of semiconductor chip - Google Patents

Abstract

PURPOSE:To accurately detect the position of an electrode pad at wire bonding before a metal wire is bonded to the electrode pad of a semiconductor chip. CONSTITUTION:A reference pattern A possessed of checking points located at the four corners of an electrode pad 2a is made to overlap the processed data image plane 6 obtained by processing the picture image of the electrode pad 2a to detect the position of the electrode pad 2a, and when it is found impossible to detect the position of the electrode pad 2a, an auxiliary pattern possessed of checking points C1 and C2 at the four sides of the electrode pads 2a is made to overlap the processed data image plane 6 to detect the position of the electrode pad 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a metal wire between each electrode pad in a semiconductor chip mounted on a lead frame or a circuit board and each lead terminal in the lead frame or a circuit pattern on the circuit board. In connection wire bonding, the present invention relates to a method for accurately detecting the position of an electrode pad of the semiconductor chip prior to bonding the metal wire to the electrode pad.

[0002]

2. Description of the Related Art Generally, as shown in FIGS. 1 and 2, an electrode pad 2a of a semiconductor chip 2 mounted on an island 1a of a lead frame 1 and a lead terminal 1b formed on the lead frame 1 are provided. In wire bonding with the metal wire 3, the metal wire 3 is first bonded to one electrode pad 2a of the semiconductor chip 2, and then the other end of the metal wire 3 is bonded. Second bonding to one lead terminal 1b corresponding to the one electrode pad 2a is performed by the electrode pad 2a in the semiconductor chip 2.
Is repeated for each of the above.

When first bonding the metal wire 3 to each electrode pad 2a of the semiconductor chip 2, the center position of the electrode pad 2a is detected in advance and the metal wire 3 is placed at the center position. First bonding should be done. Therefore, conventionally, prior to the above-mentioned first bonding, as shown in FIG. 2, the portion of the electrode pad 2a is photographed by the television camera 4 and input to the central control circuit 5, and in the central control circuit 5, By performing binarized image processing on the captured image, a processing data screen 6 as shown in FIG. 3 is obtained.

On the other hand, as shown in FIG. 4, one white checkpoint A1 is provided inside the contour of the electrode pad 2a at each of the four corners of the electrode pad 2a having a predetermined shape. , A reference pattern A formed by forming two black check points A2 outside the contour of the electrode pad 2a is stored in the central control circuit 5 in advance,
The reference pattern A is superposed on the processing data screen 6, and the contour line of the image of the electrode pad 2a on the processing data screen 6 is defined by four inner white check points A1 in the reference pattern A. , The electrode pad 2a on the processing data screen 6 is moved relatively so as to enter between the eight black check points A2 on the outside.
As shown in FIG. 5, all of the four corners of the image of No. 3 of the image entered between two outer black check points A2 and one inner check point A1 in the reference pattern A. Occasionally, the position of the center point O on the electrode pad 2a is detected, and the metal wire 3 is fast-bonded to the detected center point O, while one of the four corners in the image of the electrode pad 2a is detected. Even in one corner, when it is not between the two black check points A2 on the outside and one white check point A1 on the inside, it is undetectable, that is, NG, and the wire bonding operation is interrupted. The operator is given an alarm to that effect.

[0005]

However, each electrode pad 2a on the surface of the semiconductor chip 2 is attached to the television camera 4
At the time of shooting at, the irradiation angle of the light beam, and when the light beam is irradiated to this, the reflected light can be uneven in the irradiation angle, the surface roughness and flatness of the electrode pad 2a, etc. In the image of the electrode pad 2a obtained by subjecting the image to the image processing, although the electrode pad 2a has a predetermined shape, a part of the image is likely to be missing. .

Therefore, as in the prior art, all the four corners of the image of the electrode pad 2a on the processed data screen 6 have two outer black check points A2 in the pattern A and one inner check point. In the method of detecting the position of the center point O of the electrode pad 2a when it enters the space between the white check points A1, the shape of the electrode pad 2a is reduced due to the occurrence of a chip in the image of the electrode pad 2a. Although the position is normal, the position of the electrode pad 2a cannot be detected, and the wire bonding work is often interrupted, resulting in a significant decrease in work efficiency. there were.

According to the experiments conducted by the inventor of the present invention, it is found that the image of the electrode pad on the processing screen is defective.
It is a technical problem to mainly provide a method for recognizing an electrode pad position that can solve the above-mentioned problem, focusing on the corner of the image of the electrode pad. It is what

[0008]

In order to achieve this technical object, the present invention provides "a processing data screen obtained by image-processing a photographed image of a portion of an electrode pad on a semiconductor chip. An image of the electrode pad in the processing data screen is provided between the check patterns on the outside and the check points on the inside of the reference pattern, each of which has an outer check point and an inner check point at each corner portion. Are overlapped so that the contour line of the reference pattern is included, and all four corners of the image of the electrode pad in the processing data screen are inserted between the outer check points and the inner check points in the reference pattern. When the position cannot be detected by the means in the position detecting method for detecting the position of the electrode pad, An auxiliary pattern having an outer checkpoint and an inner checkpoint on each side of the electrode pad on the logical data screen, and the auxiliary pattern having the outer checkpoint and the inner checkpoint on the auxiliary pattern. The electrode pad images on the processed data screen are overlapped so that the contours of the images fit into each other, and four of the electrode pad images on the processed data screen are placed between the outer check points and the inner check points of the auxiliary pattern. The position of the electrode pad is detected when all the sides are included. "

[0009]

[Operation] That is, the present invention uses a reference pattern to detect the positions of the electrode pads from the four corners of the image of the electrode pads on the processed data screen.
When it is not possible to detect the position of the electrode pad due to the lack of at least one of the four corners of the image of the electrode pad on the processed data screen, the auxiliary pattern is used. The position of the electrode pad is detected from the four sides of the image of the electrode pad in FIG.

[0010]

As a result, even when the image of the electrode pad on the processed data screen is chipped due to the irradiation angle of the light beam or the surface roughness and flatness of the electrode pad, the chipping of the electrode pad The position of the electrode pad can be detected as long as it does not reach the four sides in the image.
It is possible to significantly reduce the interruption of the wire bonding work and improve the work efficiency of the wire bonding.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As in the conventional case described above, the portion of the electrode pad 2a is photographed by the television camera 4 and input to the central control circuit 5, as shown in FIG. By performing the binarized image processing, a processing data screen 6 as shown in FIG. 3 is obtained (step 1).

On the other hand, in the central control circuit 5, as shown in FIG. 4, each of the portions corresponding to the four corners of the electrode pad 2a having a predetermined shape is provided inside the contour of the electrode pad 2a. Two white check points A1 and electrode pad 2
As shown in FIG. 6, a reference pattern A formed by forming two black check points A2 outside the contour line of a,
Each of the four corners of the electrode pad 2a having a predetermined shape corresponds to two diagonal corners, and one white check point B1 and the electrode pad are provided inside the contour line of the electrode pad 2a. One black-painted check point B2 is formed outside the contour line of 2a, and the electrode pad 2a is formed on each of the corresponding portions of the four sides of the electrode pad 2a.
As shown in FIG. 8, an intermediate pattern B formed by forming one white check point B3 inside the contour line and one black check point B4 outside the contour line of the electrode pad 2a, as shown in FIG. One white check point C1 inside the contour line of the electrode pad 2a and one black check point C2 outside the contour line of the electrode pad 2a on each of the corresponding parts of the four sides of the electrode pad 2a. And the intermediate pattern C formed by forming the.

Then, the central control circuit 5 reads the reference pattern A (step 2), and outputs the reference pattern A to the processing data screen 6 as an image of the electrode pad 2a on the processing data screen 6. The outline is overlapped so that it lies between the four inner white check points A1 and the eight outer black check points A2 in the reference pattern A (step 3), and the electrode pad on the processing data screen 6 is overlapped. As shown in FIG. 5, all four corners of the image of 2a fall between two outer black check points A2 and one inner white check point A1 in the pattern A. Occasionally, the position of the center point O on the electrode pad 2a is detected, and as a detection end, the metal wire 3 is attached to the detected center point O.
While moving to the first bonding of
Even at one corner of the four corners in the image of the electrode pad 2a, the two outer black check points A2 are provided.
If it is not between the inside white checkpoint A1 and the inside checkpoint A1, it is not detected, that is, NG.

Next, when the position detection using the reference pattern A is impossible (NG), the central control circuit 5 reads the intermediate pattern B (step 4),
With respect to the processing data screen 6, the contour line of the image of the electrode pad 2a in the processing data screen 6 is defined by six white check points B1 and B3 on the inner side of the intermediate pattern B, Superimposing them so as to fall between the six black check points B2 and B4 (step 5), two corners and all four sides of the image of the electrode pad 2a on the processing data screen 6 are
As shown in FIG. 7, when it enters between the outer six black check points B2, B4 and the inner six white check points B1, B3 in the intermediate pattern A,
The position of the center point O on the electrode pad 2a is detected, and as a detection end, the metal wire 3 is fast bonded to the detected center point O, while the diagonal of the image of the electrode pad 2a is detected. One of the two corners and one of the four sides have the six black check points B2 and B4 on the outside and the six white check points B1 and B3 on the inside. When it is not within the interval, it is undetectable, that is, NG.

Further, when the position detection using the intermediate pattern B is impossible (NG), the central control circuit 5 reads the auxiliary pattern C (step 6), and the auxiliary pattern C is used as the processing data. On the screen 6, the outline of the image of the electrode pad 2a on the processed data screen 6 is between the four white check points C1 on the inner side and the four black check points C2 on the outer side of the auxiliary pattern C. All of the four sides of the image of the electrode pad 2a on the processed data screen 6 are overlapped so that they fit into each other (step 7), as shown in FIG.
At the time of entering between the four outer black check points C2 and the four inner white check points C1, the position of the center point O of the electrode pad 2a is detected, and this detection is made as the detection end. While shifting to performing the first bonding of the metal wire 3 to the center point O, the outside four black-painted check points C are formed even on one of the four sides in the image of the electrode pad 2a.
When it is not between 2 and the four white checkpoints C1 on the inside, it is undetectable, that is, as NG, an alarm to this effect is issued and the wire bonding is interrupted.

That is, first, by using the reference pattern A having the largest number of check points, the electrode pad 2a from the four corners of the image of the electrode pad 2a on the processed data screen 6 is detected.
If the position of the electrode pad 2a cannot be detected by detecting the position of the reference pattern A
The position of the electrode pad 2a is detected using the intermediate pattern B having few check points in the above, and when the position of the electrode pad 2a cannot be detected even with this, the auxiliary pattern C is used to process the processed data. The position of the electrode pad 2a is detected from the four sides of the image of the electrode pad 2a on the screen 6.

As a result, even if the image of the electrode pad 2a on the processed data screen 6 is defective due to the irradiation angle of the light beam or the surface roughness and flatness of the electrode pad 2a, the defect is generated. The position of the electrode pad 2a can be detected as long as it does not reach the four sides in the image of the electrode pad 2a. Although the position detection by the intermediate pattern B in the above-described embodiment may be omitted, as described in the above-described embodiment, the position detection by the reference pattern A and the position detection by the auxiliary pattern C may be omitted. By providing the position detection by the intermediate pattern B having the check points smaller than the check points in the pattern, the accuracy and certainty of the position detection can be further improved by the position detection by the reference pattern A and the position detection by the auxiliary pattern C. is there.

Needless to say, the present invention can be applied not only to the semiconductor chip 2 mounted on the lead frame 1 as in the above-described embodiment but also to a semiconductor chip mounted on a printed circuit board or the like.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a semiconductor chip is mounted on a lead frame.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is a diagram showing a processed data screen in which an image of an electrode pad portion of a semiconductor chip is photographed and then imaged.

FIG. 4 is a diagram showing a reference pattern.

FIG. 5 is a diagram showing a state in which the reference pattern is superimposed on the processed data screen.

FIG. 6 is a diagram showing an intermediate pattern.

FIG. 7 is a diagram showing a state in which the intermediate pattern is superimposed on the processed data screen.

FIG. 8 is a diagram showing an auxiliary pattern.

FIG. 9 is a diagram showing a state in which the auxiliary pattern is superimposed on the processed data screen.

FIG. 10 is a diagram showing a flow sheet.

[Explanation of symbols]

1 Lead Frame 2 Semiconductor Chip 2a Electrode Pad on Semiconductor Chip O Center of Electrode Pad 3 Metal Wire 4 Television Camera 5 Central Control Circuit 6 Processing Data Screen A Reference Pattern A1, A2 Check Point in Reference Pattern B Intermediate Pattern B1, B2, B3 , B4 Check point in intermediate pattern C Auxiliary pattern C1, C2 Check point in auxiliary pattern

Claims (1)

[Claims] 1. A processed data screen obtained by image-processing a photographed image of an electrode pad portion of a semiconductor chip,
A reference pattern having an outer check point and an inner check point at each of the four corners of the electrode pad, the processed data between each outer check point and each inner check point in the reference pattern. The electrodes of the image of the electrode pad on the screen are overlapped so that the outlines of the images enter, and four corners of the image of the electrode pad on the processed data screen are provided between the outer check points and the inner check points of the reference pattern. In the position detecting method which detects the position of the electrode pad even when all the parts are included, when the position cannot be detected by the means, the processing data screen is displayed on each side of the electrode pad. An auxiliary pattern having an outer checkpoint and an inner checkpoint is defined as an outer checkpoint and an inner checkpoint in the auxiliary pattern. Of the electrode pad on the processed data screen so that the outline of the image of the electrode pad on the processed data screen is included, and the processed data screen is formed between the outer check points and the inner check points of the auxiliary pattern. The method for detecting the position of the electrode pad in the semiconductor chip, wherein the position of the electrode pad is detected when all four sides are included in the image of the electrode pad.