JPH02287773A - Method for inspecting article with repeated pattern - Google Patents

Abstract

PURPOSE:To reduce the damage of an article to be checked and to eliminate a need of a complicated positioning mechanism by positioning and arranging the article in a specific direction and extracting each unit pattern image from the image pick-up result of a preliminarily determined part to compare it with a reference pattern image. CONSTITUTION:An IC lead frame material 2 as the article to be checked consists of four repeat unit patterns P1 to P4 connected in the X direction and is placed on a table 4 and is brought into contact with a contact part 4a and is positioned in the Y direction and is fixed. Three line sensor cameras CA1, CA2, and CA3 arranged at the prescribed intervals are arranged to the upper left of the lead frame material 2, and the position of the article in the X direction is measured in accordance with the image pick-up results of the preliminarily determined part of the article 2, and each unit pattern image of the article is extracted based on the measured result and is compared with the reference pattern image. Thus, the check method of the article with repeated patterns is obtained which reduces the damage of the article and does not require a complicated positioning mechanism.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for inspecting an article having a repeated pattern, and in particular, a method for optically detecting the appearance of the article, such as its shape, scratches, dirt, etc., to detect the presence or absence of defects. Concerning how to. Such optical inspection is particularly suitable for automatic inspection of planar articles such as electronic component lead frame materials, printed matter, and other articles having repetitive patterns.

[Prior art and problems to be solved by the invention] Conventionally,
Appearance inspections of various articles have often been conducted visually by workers using the naked eye or, in some cases, using an optical microscope. However, this type of visual inspection has the disadvantages that the judgments vary depending on the worker, the judgments vary depending on the working conditions even by the same worker, the worker becomes fatigued, and it is difficult to expect an improvement in the inspection speed. Ta.

Therefore, in recent years, there has been a demand for automation of testing. This automatic inspection consists of comparing a reference pattern and a pattern to be inspected and detecting the difference between them.

Although this kind of automatic inspection can be applied to the inspection of three-dimensional objects, in reality automatic inspection of three-dimensional objects is quite difficult, especially for two-dimensional objects (which are treated as essentially two-dimensional patterns). It is best applied to the inspection of electronic component lead frame materials, printed matter, etc.).

In order to obtain the pattern to be inspected, an image is taken by a camera, and an area sensor camera or a line sensor camera can be used as the camera. When using an area sensor camera, a memory for the entire number of pixels is required for the pattern to be inspected, but it has the advantage that images can be captured at once. Furthermore, when using a line sensor camera, a scanning means is required, but there is an advantage that the memory is small (comparison can be carried out in parallel with quick scanning and it is efficient).

As a method of such automatic inspection, for example, Japanese Patent Application Laid-Open No. 1983-
There are methods described in Japanese Patent Application Laid-open No. 15441 and Japanese Patent Application Laid-open No. 15380/1983.

However, in the methods described in these publications, in order to position the object to be inspected placed on a table with respect to the camera, the object to be inspected is This is done by pressing the item against each other and fixing it. Therefore, in this method, a positioning mechanism in two directions is required, which complicates the structure of the apparatus, and the ends of the inspected article are frequently damaged due to bumping.

SUMMARY OF THE INVENTION In view of the problems of the prior art as described above, an object of the present invention is to provide a method for inspecting an article having a repetitive pattern, which does not require a complicated positioning mechanism, and which causes less damage to the article to be inspected. That is.

[Means for Solving the Problems] According to the present invention, in order to achieve the above objects, an article having a unit pattern that repeats in a specific direction is divided into a plurality of areas whose end portions overlap in the specific direction. In an inspection method in which each unit pattern image is extracted from a plurality of images obtained in this way and a judgment is made by comparing these with a reference pattern image, the above-mentioned article is positioned in a direction perpendicular to the above-mentioned specific direction. and measure the position of the article in the specific direction from the imaging results of a predetermined portion of the article, extract each unit pattern image of the article based on the measurement result, and compare it with the reference pattern image. A method for inspecting an article having a repetitive pattern is provided.

In the present invention, the length of the article in the specific direction is calculated from the measurement result of the position of the article in the specific direction, and only when the length is within the allowable range, the edge of the specific direction is shifted by half the difference from the reference length. Inspection coordinates can be set by correction using the part position as a reference for unit pattern image extraction.

[Example] Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 2(a) is a schematic partial plan view showing an example of an apparatus in which the present invention is implemented, and FIG. 2(b) is a schematic front view thereof.

In these figures, reference numeral 2 denotes an IC lead frame material which is an article to be inspected, and in this embodiment, it consists of four repeating unit patterns P] to P4 connected in the X direction. The lead frame material is placed on the table 4. The mounting surface of the table is horizontal, and an abutment part 4a is formed at one end in the Y direction, and the lead frame material 2 is abutted against the abutment part 4a and is moved by means (not shown). It is positioned and fixed in the Y direction by.

An illumination light source 6 is disposed diagonally above and to the right of the lead frame material 2, and the light emitted from the light source illuminates the upper surface of the lead frame material 2. Three line sensor cameras CAL, CA2 . CA3 is located.

surface, the illumination light source 6 and the line sensor camera CAl,C
A2. The CA 3 is attached to a common support member (not shown), and these members are moved in the Y direction with respect to the table 4 by a driving means (not shown).

FIG. 3 is a schematic optical diagram showing the imaging state of each camera.

In the figure, 8-1 8-2 8-3 are cameras CAL, CA2. It is a CA3 objective lens, 10-1
10-2 and 10-3 are the cameras CAI and CA, respectively.
2. This is a line sensor that is the light receiving element of CA3. As illustrated, the line sensor of each camera has a pixel array in the X direction. K for line sensor 10-1 of camera CAL
A line-shaped area of 5 to 0 is imaged, a line-shaped area of 3 to 8 is imaged to the line sensor 10-2 of the camera CA2, and a line-shaped area of 7 to 8 is imaged to the line sensor 10-3 of the camera CA3.
A linear region of ~Kll is imaged.

The imaging area of camera CAI and the imaging area of camera CA2 overlap in areas 3 to 5, and similarly camera C
The imaging area of A2 and the imaging area of camera CA3 overlap in areas 7 to 8. Further, each unit pattern P1 to P4 of the lead frame material 2 is 1 to 2, respectively.
2~6°K6~9. The length in the X direction of 9 to 10 (
That is, it has f2).

Note that KO and Kll are located outside both ends of the lead frame material 2 in the X direction, and therefore, the inspected article 2 is completely contained within the imaging range in the X direction by the three cameras. That is, when placing and fixing the lead frame material 2 on the table 4, the position in the X direction is controlled to such an extent that such an arrangement is achieved.

Figure 4 (a) and (b) show lead frame material 2 and camera C.
AL, CA2. It is a figure which shows the imaging relationship with all the line sensors of CA3. Here, ■I, , I2 indicate optically equivalent images of the line sensor with respect to the lead frame material 2.

FIG. 1 is a flow diagram for explaining one embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be specifically described based on FIG. 1 while referring to FIGS. 2 to 4 above.

First, the lead frame material 2 is set at a predetermined position on the table 4 as shown in FIG. 2 (STl). At this time, the lead frame material is positioned in the Y direction with its end in the Y direction abutting against the abutting portion 4a, while no positioning is performed in the X direction. However, the lead frame material 2 is
It is arranged to be located within a predetermined tolerance range in the X direction, and within this tolerance range, as shown in FIG.
It is designed to be within the imaging range of the camera on the stand.

Next, the cameras CA1 and CA2 are driven by a driving means (not shown).
．． The CA 3 and the illumination light source 6 are moved in the Y direction, and the camera is placed at a predetermined position for measuring the position of the lead frame material 2 in the X direction (Sr1). The predetermined position is, for example, a position where the optical equivalent image of the line sensor is located as shown in FIG. It is a position that appears to be a surface). Such a position can be set in advance in relation to the abutting portion 4a.

Next, images are taken using three cameras (Sr1).

Next, the length L in the X direction of the lead frame material 2 is calculated based on the result of the imaging in ST3 (Sr1). This calculation can be obtained from the sensor bits at both ends of the sensor bits where the presence of the lead frame material 2 is detected.

Specifically, the length L is (number of camera bits corresponding to 1.O in Kl-) x (length of camera 1 bit in the X direction)/(
It can be determined by the camera's imaging magnification.

Next, it is determined whether the length L is within a predetermined allowable range (Sr1). In other words, the standard value. The error δ is measured by (LL, ), and it is determined whether IL-LO+ is larger than the allowable error.

If the error is within the allowable range in ST5 above, then the inspection coordinates in the X direction are set (Sr1)
. This setting is for making a correction to set the position obtained by adding the distance δ/2 to 1 as the X-direction measurement start coordinate for unit pattern extraction. As a result, all patterns P1 to P
4 can be extracted with the smallest error within the range of the KS-KE region (length in the X direction) shown in FIG. 4(a).

Following ST6 above, each unit pattern is inspected (
Sr7). This inspection is performed by taking images while moving the three cameras mentioned above in the Y direction relative to the lead frame material 2 (
That is, the optically equivalent mechanism of the line sensor shown in FIG. 4(a) is scanned in the Y direction), and based on the imaging results, the imaging pattern image of each camera is appropriately decomposed using the inspection coordinates set in ST6 above. Furthermore, images of each of the unit patterns P1 to P4 are obtained by appropriately combining the images, and these are compared with a reference pattern image, thereby determining whether a good product or a defective product is present based on a predetermined standard. Incidentally, such an inspection is described, for example, in the above-mentioned Japanese Patent Application Laid-Open No. 63-15141 and Japanese Patent Application Laid-Open No. 63-1538.
This can be carried out as described in Publication No. 0.

On the other hand, if the error is outside the allowable range in ST5, then defective product processing is performed (Sr1) and unit pattern inspection is not performed. This defective product processing is performed by collecting the lead frame material 2 as a defective product using an appropriate sorting means.

The predetermined position to which the camera moves in ST2 is, for example, as shown in FIG. The position may be such that the position of the abutting portion 4a is the same as that of the abutting portion 4a. In this case, when calculating the length of the lead frame material 2 in the X direction in ST4, the length determined from the sensor bits at both ends of the sensor bits where the presence of the lead frame material 2 is detected. The length L of the lead frame material 2 can be determined by conversion based on .

In the embodiments described above, the lead frame material 2 is hardly damaged or deformed even if the end portion in the Y direction is abutted against the abutting portion 4a of the table 4. and,
If the lead frame material 2 is abutted against the end in the X direction, the thin part of the end is likely to be damaged or deformed, but in the above embodiment, the end in the X direction is abutted against the abutment part. Since it is not covered, it will not be damaged or deformed.

Further, in the above embodiment, the lead frame material 2 is Y
Since positioning is performed in the direction and not in the X direction, the positioning mechanism of the device is simplified.

It goes without saying that the present invention is applicable not only to the above-mentioned lead frame materials but also to the inspection of other articles.

[Effects of the Invention] As explained above, according to the present invention, there is provided a method for inspecting an article having a repeated pattern, which is less likely to damage the inspected article and does not require a complicated positioning mechanism.

The present invention prevents the occurrence of defective products by positioning and fixing the object by abutting the end in the direction in which it is less likely to be damaged, when the end of the object to be inspected is easily damaged by abutment in only one of two directions. It is particularly effective in preventing

[Brief explanation of drawings]

FIG. 1 is a flow diagram for explaining one embodiment of the present invention. FIG. 2(a) is a schematic partial plan view showing an example of an apparatus in which the present invention is implemented, and FIG. 2(b) is a schematic front view thereof. FIG. 3 is a schematic optical diagram showing the imaging state of each camera. FIGS. 4(a) and 4(b) are diagrams showing the imaging relationship between the lead frame 4j and all line sensors of the camera. 2: Lead frame material, 4: Table, 4a: Abutting portion, 6: Illumination light source, 8-1 to 8-3; Objective lens, 10-1 to 10-3 Ni line sensor, CAL to CA3: Line sensor camera , P1 to P4:
unit pattern.

Claims (2)

[Claims] (1) An article having a unit pattern that repeats in a specific direction is imaged in multiple areas where the ends overlap each other in the specific direction, and each unit pattern image is extracted from the multiple images thus obtained, and these are In an inspection method in which a determination is made by comparing with a reference pattern image, the article is positioned and arranged in a direction perpendicular to the specific direction, and the position of the article in the specific direction is determined from the imaging result of a predetermined portion of the article. 1. A method for inspecting an article having a repeated pattern, the method comprising: measuring a unit pattern of the article, extracting each unit pattern image of the article based on the measurement results, and comparing the extracted unit pattern image with the reference pattern image. (2) Calculate the length of the article in the specified direction from the measurement result of the position of the article in the specified direction, and only if the length is within the allowable range, the end position in the specified direction is shifted by half the difference from the reference length. 2. The method for inspecting an article having a repetitive pattern according to claim 1, wherein the inspection coordinates are set by correction using the unit pattern image as a reference for extracting the unit pattern image.