JP4180127B2 - Cream solder printing inspection apparatus and cream solder printing inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cream solder printing inspection apparatus and a cream solder printing inspection method for inspecting a printing state of cream solder used when an electronic component or the like is mounted on a circuit board.
[0002]
[Prior art]
In recent years, in high-density mounting of electronic components, a means for printing cream solder on a circuit board land and heating and soldering the cream solder is widely used. However, the printing state of the cream solder affects the soldering quality. Therefore, it is required that the printing state can be accurately inspected.
[0003]
FIG. 4 is a schematic view showing a conventional cream solder printing inspection apparatus. In the figure, 1 is a circuit board on which a cream solder 3 is printed on a land 2, 4 is an XY table for positioning the circuit board 1, and 5 is a circuit board 1, a land 2, and a cream solder 3 so as not to be shaded. Diffuse illumination device for illuminating, 6 is a monochromatic camera (hereinafter referred to as a monochrome camera), 7 is a grayscale image processing device that obtains an image of cream solder by performing grayscale image processing on an image from the monochrome camera 6 based on luminance distribution, and 8 is a display device For example, a personal computer or the like can be used.
[0004]
In the above configuration, the cream solder 3 printed on the land 2 of the circuit board 1 is positioned at a predetermined position by the XY table 4 and photographed by the monochrome camera 6 under the diffuse illumination by the diffuse illumination device 5. The image includes the image of the land 2, but the image of the cream solder 3 is obtained separately from the image of the land 2 by processing based on the luminance distribution by the grayscale image processing device 7, and the cream solder 3 is obtained from the image. The state, position, area, etc. are obtained and compared with the reference value, and the printing state of the cream solder 3 is inspected. Further, there is a case in which the printing state is inspected by irradiating the three-dimensional laser light and adding the height information of the cream solder 3.
[0005]
FIG. 5A is a cross-sectional view showing a state of the cream solder 3, and FIG. 5B is a characteristic diagram showing an example of luminance distribution of a gray image obtained by the conventional cream solder printing inspection apparatus. As shown in the figure, since the brightness of the cream solder 3 is smaller than that of the land 2, the image portion with the lower brightness is determined as the image of the cream solder 3, and the cream solder 3 is printed with respect to its state, position and area. Checking the condition.
[0006]
[Problems to be solved by the invention]
In such a conventional cream solder printing inspection apparatus, the land 2 and the cream solder 3 are separated and determined only by the luminance distribution of the grayscale image. Therefore, as shown in FIG. When the brightness is approximately the same, the land 2 and the cream solder 3 cannot be completely separated. For example, the central recessed portion of the cream solder 3 shown in FIG. Therefore, there is a problem that it is determined that the cream solder 3 is defective even if it is determined that the cream solder is absent.
[0007]
Even when a three-dimensional laser beam is used, it cannot be accurately determined depending on the surface state of the cream solder 3 and has a drawback that the inspection speed is slow.
[0008]
The present invention solves the above-described problem. Even when the brightness of the land 2 and the brightness of the cream solder 3 are approximately the same, the printing state is accurately determined with respect to the state, position, area, and the like of the cream solder 3. Another object of the present invention is to provide a cream solder printing inspection apparatus and a cream solder printing inspection method which can be inspected at high speed.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the state of the cream solder printed on the land of the substrate is illuminated only from vertically above, color photography is performed from above vertically , and the image of the land is extracted by color extraction from the color image, Cream solder printing in which the extracted image of the land is removed from the gray image in the color image to obtain a gray image of the cream solder only, and the print state of the cream solder is inspected by the gray image of the cream solder only Use inspection methods.
[0010]
As a result, the printing state of the cream solder can be accurately inspected with respect to the state, position, area, etc. by eliminating the influence of the image of the land, and since it is a means that does not use a three-dimensional laser beam etc., it is fast. Can be inspected.
[0011]
Further, the present invention according to claim 2 is a gray-scale image of only the cream solder obtained by color-shooting the cream solder printed on the lands of the circuit board and excluding the land image from the color image obtained by the color photography. Is produced, and the printed state of the cream solder is inspected from the gray image thereof.
[0012]
Thereby, the printed state of the cream solder can be inspected accurately and at high speed with respect to the state, position, area, etc. by eliminating the influence of the land image.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention according to claim 1 or 2, the means for obtaining a gray image only of cream solder from a color image stores a color extraction circuit for extracting a color image of a land from the color image, and stores the gray image of the color image. And an image processing circuit that removes the extracted land image from the grayscale image stored in the grayscale image memory and generates a grayscale image only of cream solder.
[0014]
The display means may simply display the grayscale image. For example, a personal computer and its display can be used to automatically measure the area and the like of the grayscale image and to make an automatic determination. .
[0015]
Examples will be described below.
[0016]
【Example】
Hereinafter, an embodiment of a cream solder printing inspection apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of this embodiment. The same constituent elements as those in the conventional example shown in FIG. In the figure, 9 is a color imaging device, and 10 is a solder image generating device. The solder image generation apparatus 10 includes a color conversion circuit 11, a color extraction circuit 12, a grayscale image memory 13, and an image processing circuit 14. This embodiment is different from the conventional example in that color photography is performed, the image of the land 2 is extracted by color extraction, the image of the land 2 is removed from the grayscale image to obtain a grayscale image of only the cream solder 3, and the grayscale This is because the printing state of the cream solder 3 is inspected from the image.
[0017]
The operation of the above configuration will be described. The cream solder 3 printed on the land 2 of the circuit board 1 is positioned at a predetermined position by the XY table 4 and photographed by the color imaging device 9 under illumination by the diffuse illumination device 5. The color image obtained by the color image pickup device 9 is extracted by the color image extraction circuit 12 via the color conversion circuit 11 in the solder image generation device 10 and the gray image of the color image is stored in the gray image memory 13. Then, the image processing circuit 14 removes the extracted image of the land 2 from the grayscale image to obtain a grayscale image of only the cream solder 3.
[0018]
FIG. 2 is a schematic diagram showing the image processing in this embodiment corresponding to the printing state of the cream solder. In the conventional cream solder printing inspection apparatus, the dent 3c of the land 2 and the cream solder 3 has the same luminance and cannot be distinguished from the land 2, and erroneously determines that the cream solder 3 is missing. However, according to the present embodiment, as shown in the figure, the image of the land 2 is extracted by color extraction, and the image of the land 2 is removed from the grayscale image, so that only the cream solder 3 composed of 3b and 3c is obtained. Can be generated separately from the image of the land 2. In this state, as shown in FIG. 2A, it can be determined that 3c is indented by the top 3b of the cream solder 3 and the luminance distribution at the center thereof, and it is erroneously determined that the cream solder 3 is missing. There is no. Further, when the luminance distribution of 3b is observed, it can be determined that the cream solder 3 has an inclined portion 3a, i.e., dripping, because the luminance of the peripheral portion is small in the state of FIG. In the state shown in 2 (b), since the luminance distribution of 3b is uniform throughout, it can be determined that the cream solder 3 is hardly dripped, and the dripping state of the cream solder 3 is determined from the luminance distribution. You can also.
[0019]
FIG. 3 is a flowchart showing the operation of this embodiment. In step 1, the color imaging device 9 images the land 2 and the cream solder 3, and in step 2, pre-processing is performed by the color conversion circuit 11 in the solder image generation device 10. In step 3, the color extraction circuit 12 performs an image of the land 2. Is separated from the image of the cream solder 3 by color extraction, and the gray image stored in the gray image memory 13 in step 4 is processed by the image processing circuit 14 to remove the image of the land 2. In step 5, the cream solder 3 is extracted. In step 6, the state, position and area of the cream solder 3 are detected, and in step 7 to step 9, the state, position and area of the cream solder 3 are determined respectively. If it passes, it is judged as a non-defective product and the process ends. Judgment and ends with the bad in-flops 10.
[0020]
As described above, according to the present embodiment, the land 2 and the cream solder 3 are picked up by the color image pickup device 9, and the image of the land 2 is extracted by color extraction by the solder image generating device 10 and obtained from the color image. By removing the image of the land 2 extracted from the grayscale image, a grayscale image of only the cream solder 3 is generated, and the printing state of the cream solder 3 is inspected with respect to the state, position, area, and the like by the luminance distribution. Thus, the influence of the brightness of the land 2 can be eliminated, and the state of the cream solder 3 alone can be determined, the printed state of the cream solder can be accurately inspected, and it is not a means using laser light. Inspection can be performed at high speed.
[0021]
It is also possible to display the grayscale image on the display device 8 and visually inspect it. However, it is connected to a personal computer or the like to display the grayscale image and automatically measure the area, etc. It goes without saying that it can be executed.
[0022]
【The invention's effect】
As apparent from the above description, the present invention captures the state of the cream solder printed on the land in color, extracts the land image from the color image by color extraction, removes it from the image, and removes only the cream solder. Since the gray image is obtained and the state, position, area, etc. of the cream solder are determined from the gray image, the influence of the land image can be eliminated and the printed state of the cream solder can be accurately and rapidly inspected.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of an embodiment of a cream solder printing inspection apparatus according to the present invention. FIG. 2 is a schematic diagram showing image processing in the embodiment corresponding to the printing state of cream solder. FIG. 4 is a schematic diagram showing the configuration of a conventional cream solder printing inspection apparatus. FIG. 5 is a cross-sectional view showing the state of cream solder and a characteristic diagram showing luminance distribution in a grayscale image in the conventional example. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circuit board 2 Land 3 Cream solder 4 XY table 5 Diffuse illumination apparatus 6 Monochrome camera 7 Grayscale image processing apparatus 8 Display apparatus 9 Color imaging device (color imaging means)
10 Solder image generating device (solder image generating means)
11 color conversion circuit 12 color extraction circuit 13 grayscale image memory 14 image processing circuit

Claims (1)

The state of the cream solder printed on the land of the board is illuminated with light only from above vertically, color photography is performed from above vertically , the image of the land is extracted from the color image by color extraction, and the grayscale image in the color image A cream solder printing inspection method in which the extracted image of the land is removed to obtain a gray image of only the cream solder, and the printed state of the cream solder is inspected by the gray image of only the cream solder.

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