JP2001208703A - X-ray inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the binarized image of the adhesion state of an adhesive can not be accurately obtained according to circumstances by the effect of the copper pattern of a printed circuit board or the like in the case where an original image is binarized when the adhesion state of the adhesive state of an object to be inspected is inspected by an X-ray transmission image. SOLUTION: The length and breadth dimension, the number of rows and lines and the diameter of the adhesion state of the adhesive of the object to be inspected are set on the basis of an X-ray original image and, on the basis of these set values, a square mask frame is formed on the X-ray original image displayed on the screen of a computer. The mask frame is arranged at a proper position so that it is received in the adhesion part of the X-ray original image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray inspection apparatus used for X-ray nondestructive inspection in inspection of electronic components mounted on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, when an original image is binarized when an adhesion state of an object to be inspected on a printed circuit board is inspected by using an X-ray transmission image, one arbitrary gradation value (the entire image) is used. The threshold value is used as a boundary, and a binarized image for inspection is obtained by a binarizing method in which the image is divided into a white portion and a black portion.

[0003]

In the above-mentioned conventional image binarization method, there is a case where an image obtained by capturing an adhesion state of an adhesive on an object to be inspected by X-rays cannot be correctly binarized. there were.

FIG. 6 is an X-ray original image of the bonding state of the adhesive on the inspection object in the X-ray inspection apparatus. FIG. 9 is a binarized image that has been subjected to binarization processing in which the image is divided into a black portion and a white portion with one arbitrary threshold value in the original image as a boundary. As shown in FIG. 9, in the lower left portion of the image, it can be seen that the density of the background of the adhesive influences and the adhesive state of the adhesive is not obtained as a good binary image. In other words, the pattern of the copper on the printed circuit board affects the image density of the background image of the object to be inspected may not be uniform.One arbitrary threshold value is applied to the entire image, and the image is defined as a white portion. With the binarization method of distributing to the black portion, it was not possible to obtain a binarized image of the adhesive state suitable for the inspection.

According to the present invention, an X-ray image obtained by capturing an adhesion state of an adhesive on an object to be inspected can be accurately obtained as a good binary image irrespective of the influence of a copper pattern or the like on a printed circuit board. It is an object of the present invention to provide an image processing unit that realizes a binarization process and obtains a binarized image from which pass / fail can be determined.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a masking section for masking an individual bonding portion of an adhesive of an object to be inspected, and a configuration image in each mask frame. It is composed of a threshold value deciding unit for deciding suitable individual threshold values, and a binarization processing unit for binarizing a constituent image in the mask frame using the individual threshold values.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS With the above arrangement, a printed circuit board is determined by determining a binarization threshold suitable for a constituent image in a mask frame in which individual adhesive portions of an adhesive of an inspection object are masked. A good binarized image can be obtained regardless of the density of the background of the image due to the copper pattern or the like.

(Embodiment) FIG. 1 is a flowchart showing the overall processing in an X-ray inspection apparatus. FIG. 2 is a flowchart of a masking unit that creates a mask frame surrounding the adhesive portion of the inspection object. FIG. 3 is a flowchart of a calculation unit that determines a binarization threshold suitable for a constituent image in each mask frame. FIG. 4 is a flowchart of a binarization process for performing binarization based on the threshold value obtained by the above-described threshold value calculation unit. FIG. 5 is a configuration diagram of the X-ray inspection apparatus. FIG. 6 is an original image of the inspection object transmitted by X-rays. FIG. 7 shows a mask frame arranged on the original image created by the masking unit described above. FIG. 8 shows a binarized image obtained by binarizing the original image by the above-described binarization processing.

An embodiment of the present invention will be described below with reference to the drawings.

[0010] As shown in FIG.
After starting the inspection software, the inspection target 3 is moved to the X-ray imaging position by the teaching operation of the printed circuit board 2 in the inspection apparatus. When an X-ray is emitted from the X-ray generation unit 1 in accordance with the X-ray irradiation instruction, the X-ray is captured by the sensor 5 as an image signal into the A / D board 7 of the personal computer 6. After being converted into a digital signal by the A / D board 7, it is captured as 12-bit image information and stored in the storage device 8. The stored image is displayed on the display device 9. FIG. 6 is a diagram illustrating an X-ray original image displayed on the display device.

Next, the details of the masking section of FIG. 1 will be described with reference to the flowchart of FIG. Based on the X-ray original image on the display device, the user inputs the vertical and horizontal sizes of a rectangular mask frame that is expected to uniformly fit the adhesive of the inspection object. Next, the number of rows and columns of the mask frame and the diameter of the bonding portion are set. Therefore, the images of the individual adhesives can be set to have substantially the same area. The input value may be input based on a design value of the inspection object. Next, in response to a mask frame creation instruction, a mask frame is displayed on the original X-ray image on the display device based on the input mask frame length and width and the number of rows and columns. Next, the mask frame is moved in accordance with the mask frame moving instruction so that the individual mask frames are evenly fitted in the bonding portions of the individual adhesives. If the bonding portions of the individual adhesives do not fit evenly within the mask frame, the set mask frame length and width and the number of rows and columns are set again and adjusted. The grid-like eyes shown in FIG. 7 are the mask frames containing the adhesive portions of the adhesive arranged on the original X-ray image.

Next, the details of the threshold value determining section of FIG. 1 will be described with reference to the flowchart of FIG. The gradation values (8 bits, 256 gradations) of the pixels constituting the image in each of the created mask frames are sequentially changed from the maximum gradation value (255 gradations) to the minimum value (0 gradations). Change. The gradation value k at the time of the change is compared with the gradation values of the pixels forming the image in the mask frame, and the number n of the black portions is added when the gradation value of the pixel is small. After performing the comparison and addition processing for all the pixels constituting the image in the mask frame, the area calculated by the set diameter of the bonding portion is converted into the number s of pixels, and the value is calculated. Is compared with the number n of the black portions. If the number n of the added black portions is larger, n is stored in n ′, and the comparison process with the gradation value is performed so that the gradation value k becomes 0. Repeat until it is. When the number n of black portions is equal to or less than the number s of pixels, the repetition of the comparison process is interrupted. Next, both the absolute value of the difference between the number s of pixels and the number n of black portions and the absolute value of the difference between the number s of pixels and the number n ′ of the stored black portions are compared, and the number of pixels The tone value k or k + 1 for which n or n ′ having a value closer to s is calculated is stored as a threshold value in the mask frame. This calculation process is performed for all the individual mask frames.

Next, the details of the binarizing section in FIG. 1 will be described with reference to FIG. The processing is repeated for the number of times equal to or less than the number of mask frames created by the masking unit. The gradation value of the constituent pixel in each mask frame is compared with the threshold value of each mask frame recorded by the above-described threshold value determination unit, and the pixel having a gradation value larger than the threshold value is compared with the white portion. Then, image processing is performed using pixels having a tone value equal to or less than the threshold value as a black portion. This comparison process is performed for all the pixels in the mask frame. FIG.
Is an image obtained by binarizing the original X-ray image.

By performing the binarization processing according to the embodiment as described above, the correct binarization threshold value is not affected by the state of the background image of the inspection object due to the copper pattern or the like on the printed circuit board. It can be calculated and a good binarized image can be obtained.

[0015]

As is clear from the above description, according to the present invention, the present invention is not affected by the copper pattern and the like of the printed circuit board.
An appropriate threshold value for binarization can be calculated for each adhesive bonding portion of the inspection object, and the binarization threshold value is calculated based on the gradation value of the constituent pixel of each adhesive bonding portion. By comparing and allocating to a black portion and a white portion, it is possible to obtain a good binary image and to provide an X-ray inspection apparatus with high accuracy of quality judgment.

[Brief description of the drawings]

FIG. 1 is an overall processing flowchart of an X-ray inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart of a masking unit according to one embodiment of the present invention.

FIG. 3 is a flowchart of a binarization threshold value determining unit according to the embodiment of the present invention;

FIG. 4 is a flowchart of a binarizing unit according to the embodiment of the present invention;

FIG. 5 is a configuration diagram of an X-ray inspection apparatus according to an embodiment of the present invention.

FIG. 6 is a diagram showing an original X-ray image of a printed circuit board;

FIG. 7 is a diagram illustrating a mask frame created on an original image by a masking unit according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating a binarized image that has been subjected to image processing by a binarization unit using a binarization threshold value of a threshold value determination unit according to an embodiment of the present invention.

FIG. 9 is a diagram showing a binarized image obtained by performing image processing on a whole conventional X-ray original image using a fixed threshold value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray generation part 2 Printed circuit board 3 Inspection object 4 Adhesive 5 Sensor 6 Personal computer 7 A / D board 8 Storage device 9 Display device 10 Irradiation field

Claims (5)

[Claims] An X-ray source for irradiating X-rays, a sensor for detecting X-rays transmitted through an object to be inspected, and a plurality of adhesives applied to the object to be inspected are separated for each individual adhesive. An X-ray inspection apparatus having a masking unit for masking. 2. An X-ray source for irradiating X-rays, a sensor for detecting X-rays transmitted through an object to be inspected, and a threshold value for determining a threshold value of a gray scale of an image formed by the X-rays transmitted through the adhesive. An X-ray inspection apparatus, comprising: a setting unit, wherein the threshold value is determined for each image of the adhesive. 3. An X-ray source for irradiating X-rays, a sensor for detecting X-rays transmitted through an object to be inspected, and an area determining unit for previously determining an area of the adhesive in an X-ray image. A threshold setting unit that determines a threshold value of a gray scale of an image formed by the X-rays transmitted through the adhesive, and determining the threshold so that the images of the individual adhesives have substantially the same area. Characteristic X-ray inspection equipment. 4. An X-ray source for irradiating X-rays, a sensor for detecting X-rays transmitted through an object to be inspected, and an image of a plurality of adhesives applied to the object to be inspected, A masking unit for masking each image, and a threshold setting unit for determining a threshold value of a gray scale of an image by X-rays transmitted through the adhesive, wherein the threshold value is set for each section masked by the masking unit. X characterized by determining
Line inspection equipment. 5. An X-ray source for irradiating X-rays, a sensor for detecting X-rays transmitted through an object to be inspected, and an image of a plurality of adhesives applied to the object to be inspected as individual adhesives. A masking section for masking each image, an area determining section for determining an area of the adhesive portion in the X-ray image in advance, and a threshold value of a gradation of an image by X-rays transmitted through the adhesive. An X-ray inspection apparatus, comprising: a threshold setting unit, wherein the threshold is determined so that the images of the individual adhesives have substantially the same area.