KR101118210B1 - Visual inspection system of printed circuit board and method of the same - Google Patents

Abstract

The present invention relates to a method for inspecting the appearance of a printed circuit board unit, the method for inspecting the appearance of the present invention comprising: dividing the entire inspection area of the inspection object into a first area and a second area; Imaging the entire inspection area of the inspection object with the first camera and the second camera using different illumination; And determining whether the first area is defective using the first image acquired from the first camera, and determining whether the second area is defective using the second image acquired by the second camera.

Printed Circuit Board, Green Lighting, Red Lighting, Visual Inspection

Description

VISUAL INSPECTION SYSTEM OF PRINTED CIRCUIT BOARD AND METHOD OF THE SAME

The present invention relates to a system and method for inspecting the appearance of a printed circuit board.

Printed circuit boards, which are one of the main materials used in the manufacture of various semiconductor devices such as driver integrated circuits and memories of liquid crystal displays, are flexible such as film and tape types according to the trend of miniaturization and light weight of semiconductor devices. Flexible printed circuit boards are used a lot. Among flexible printed circuit boards, for example, a tape automatic bonding (TAB), a chip on film (COF) substrate, and the like are formed, and a fine circuit pattern is formed on the substrate through an exposure, development, and etching process.

Manufacturers of such flexible printed circuit boards are conducting inspection processes using the AVI to inspect the entire appearance before final shipment. Manufacturers of flexible printed circuit boards can inspect the exterior inspection more efficiently and quickly. Require inspection equipment.

The present invention provides a system and method for inspecting the appearance of a printed circuit board capable of improving an inspection speed.

The present invention provides a system and method for inspecting the appearance of a printed circuit board capable of inspecting optimized inspection areas.

The problem to be solved by the present invention is not limited thereto, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The appearance inspection system of the present invention includes a stage on which an inspection object is placed; Including an inspection unit for inspecting an inspection object placed on the stage; The inspection unit may include a first photographing member configured to photograph an inspection object using first illumination; A second photographing member which photographs an object to be inspected using a second light; And inspecting a first region in a first image provided from the first photographing member, and inspecting a second region in a second image provided from the second photographing member; Including an image processing unit for integrating the two test results to determine whether there is a final failure; The first area and the second area are areas different from each other in the inspection object.

According to an embodiment of the present invention, the first light and the second light are different kinds of lights, the first light is coaxial fall light, and the second light is condensed light.

According to an embodiment of the present invention, the first light is a light having a red wavelength, the second light is a light having a green wavelength, and the first and second lights are LED lights.

According to an embodiment of the present invention, the first photographing member and the second photographing member further include a moving member for moving the first photographing member and the second photographing member together so that the photographing object can be continuously photographed in line units. Include.

According to another embodiment of the present invention, the method for inspecting the appearance of the inspection object of the present invention comprises the steps of: obtaining a first image of the inspection object by providing a first illumination; Providing a second light to obtain a second image of the inspection object; Determining whether the first image is defective or not in the first image, and determining whether the second image is defective or not in the second image; The first area and the second area are areas different from each other in the inspection object.

According to an embodiment of the present invention, the first region and the second region may have a region overlapping each other.

According to an embodiment of the present invention, there is no region where the first region and the second region overlap each other.

According to an embodiment of the present invention, the camera for acquiring the first image and the second image are different.

According to an embodiment of the present invention, the first and second images are images of the same imaging area of the inspection object, and the first image and the second image are images of different resolutions.

According to an embodiment of the present invention, the first area and the second area are divided into inspection areas for each item of the inspection object.

According to another embodiment of the present invention, the appearance inspection method of the present invention comprises the steps of: dividing the entire inspection area of the inspection object into a first area and a second area; Imaging the entire inspection area of the inspection object with the first camera and the second camera using different illumination; And determining whether the first area is defective using the first image acquired from the first camera, and determining whether the second area is defective using the second image acquired by the second camera.

According to an embodiment of the present invention, the first area and the second area are divided into inspection areas for each item of an inspection object.

According to an embodiment of the present invention, the first camera is photographed using coaxial falling illumination, and the second camera is photographed using condensed illumination.

According to an embodiment of the present invention, the first camera photographs using the LED light having a red wavelength, and the second camera photographs using the LED light having a green wavelength.

According to one embodiment of the present invention, in the determining step, if any one of the defects in the first region and the defect in the second region is defective, the final inspection result is determined as defective.

According to an embodiment of the present invention, the first region includes a cover layer region among the inspection regions for each item of the inspection object, and the second region is a plating region among the inspection areas for each item of the inspection object. And a solder resist (SR) region.

According to the present invention, the inspection for each region optimized according to the illumination type is possible.

Moreover, according to this invention, an inspection speed and inspection reliability can be improved.

In addition, according to the present invention, inspection can be performed with high-quality images obtained by using illumination having a wavelength band of color optimized for each inspection region as necessary, so inspection is very efficient.

In addition, according to the present invention, since some images may be provided with a low quality according to the inspection area, the size of the image data may be reduced, and thus, the processing speed for discriminating between two or more non-payments may be increased.

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to FIGS. 1 to 4. The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following embodiments. This embodiment is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings are exaggerated to emphasize a more clear description. In the drawings, components which perform the same function are denoted by the same reference numerals.

1 is a diagram illustrating an example of an inspection object, which is a flexible printed circuit board, divided into inspection areas for each item. Referring to FIG. 1, the inspection object may include a plating region 1, a solder resist (SR) region 2, a cover layer (CL) region 3, an overcoating (O / C) region ( It can be divided into inspection areas for each item such as 4). The inspection areas for each item may exist or may not overlap each other.

In the visual inspection system of the present invention, the plating area 1, the solder resist (SR) area 2, the cover layer (CL) area 3, the overcoating (O / C) area 4 Appearance inspection for the inspection areas including the.

For reference, since the flexible printed circuit board (FPCB) is mainly used for contact (contact), it must be possible to surface mount various electronic devices on the product and have flexibility. If the conductor circuit is exposed to the outside during the use of the flexible printed circuit board, the product is inevitably damaged during repeated / long-term use and a conductor protective film or polymer insulator (INK) may be applied to prevent this.

Here, the overcoating (O / C) region is a region in which the conductor circuit is coated with a polymer insulator having excellent performance in insulation and bending. In general, it is not used to protect a large part of a conductor circuit such as a cover lay (C / L), but is used to protect a limited small area such as protecting silver paste (Ag Paste). . In addition, the cover lay (C / L) region is a region coated with a film having insulation and bendability as a protective role to protect the conductor circuit formed on the product surface against damage caused by external factors. Of course, the present invention can also be applied to other types of substrate appearance inspection in addition to the flexible substrate.

Figure 2 is a schematic diagram showing the main configuration of the appearance inspection system according to an embodiment of the present invention.

2, the appearance inspection system 1 according to an embodiment of the present invention by item of the inspection object 10, which is a flexible printed circuit board using the first and second photographing members 300, 400 using different illumination. It is a system that can inspect inspection areas.

The appearance inspection system 1 includes a stage 100 on which the inspection object 10 is placed and an inspection unit 200 for inspecting the inspection object 10 placed on the stage 100.

The inspection unit 200 may include a first photographing member 300, a second photographing member 400, a moving member 500, and an image processor 600.

The first photographing member 300 includes a first camera 310 and a first illumination 320. The first light 320 is a coaxial fall-off illumination and consists of a metal halide illumination equipped with an LED having a red wavelength or a red filter. The first photographing member 300 using the first illumination 320 of the coaxial drop method having a red wavelength includes a plating area, a solder resist (SR) area, and a coverlay (C / L; It is most suitable for inspecting the plating area and the coverlay (C / L) area among the layer area and the over coating area.

The first illumination 320 of the coaxial fall-off method having a red wavelength band can acquire a clearer image than the illumination of other wavelength bands in the plating region and the coverlay region. In order to inspect the plating area, inspection of the surface unevenness and stain discoloration should be performed on the area of the part exposed to the surface, and the coaxial falloff method irradiated perpendicularly to the surface is very advantageous. In addition, in order to inspect the conductor circuit existing under the coverlay region, an image must be obtained by penetrating the coverlay. For this purpose, by using a red wavelength light similar to a translucent orange coverlay, the image is more clearly captured than other wavelengths. This is possible. In addition, when the red wavelength band of light similar to the coverlay is used, images of the coverlay surface may be clearly captured.

The second photographing member 400 includes a second camera 410 and a second illumination 420. The second lighting 420 uses different lighting from the first lighting 320. The second light 420 is a condensed light and consists of a metal halide light equipped with an LED or a green filter having a green wavelength. The second photographing member 400 using the second light 420 of the condensing method having the green wavelength includes a plating area, a solder resist (SR) area, and a cover layer (C / L), which are inspection areas for each item of the inspection object. It is most suitable for inspecting solder resist (SR) region and overcoating (O / C) region among)) and over coating (O / C) regions.

For example, the reason for using green LED lighting to inspect solder resist (SR) areas is to get a more accurate (sharp) image. For example, the inspection object 20 is covered with a green solder resist SR which is an insulating component over the pattern component. If the white or red illumination is used, the pattern is not clearly captured due to the solder resist. However, when irradiated with green LED light having the same or similar wavelength as the color of the solder resist, the LED light of the same wavelength passes through the solder resist layer to brighten the inner surface of the pattern. Thus, with green LED lighting, the pattern inside the solder resist is imaged cleanly (as if there is no SR). As the lights used in the present invention, various lights equipped with color filters in addition to LEDs and metal halides may be used.

As described above, the second image pickup member 400 may use the illumination having a wavelength similar to that of the solder resist to cleanly obtain images not only in the foreign material in the solder resist of the SR region but also in the patterns therein.

And similar effects can be obtained in the overcoating (O / C) area because of the use of polymer insulators similar to solder resists.

The reason why the first photographing member 300 and the second photographing member 400 use illumination of different wavelengths in the present invention is that a clear (clear) image can be obtained for each wavelength in the inspection region. For example, according to the present invention, a high quality image can be obtained by using an illumination having a wavelength band of color (similar color) optimized according to the characteristics of each inspection area as needed.

The moving member 500 moves the first photographing member 300 and the second photographing member 400 so that the first photographing member 300 and the second photographing member 400 photograph the inspection object 10 in line units. It is a linear movement device for moving. The moving member 500 may move the first photographing member 300 and the second photographing member 400 one-way from one side to the other side of the inspection object 10 or reciprocally when inspecting the inspection object 10. have. Here, the moving member 500 may be a cylinder type using a hydraulic pressure or a variety of linear movement method using a motor, a ball screw and a transfer nut.

In the present invention, the first camera 310 of the first imaging member 300 and the second camera 410 of the second imaging member 400 both photograph the entire area of the inspection object 10 in the same manner. The image processing unit 600 uses only the image of the area optimized by the first and second illuminations 320 and 420 from the first and second images of the entire area of the inspection object provided from the first and second cameras 310 and 410. It will be compared with the reference image. For example, the imaging regions of the inspection object obtained for the first image and the second image may be different from each other, and the first image and the second image may be obtained by one camera. In addition, the first image and the second image may be obtained by the same illumination.

The image processing unit 600 is a typical computer system (aka micom), and the image processing unit 600 receives a first image from the first photographing member 300, and receives a second image from the second photographing member 400. This is compared with the reference data to determine whether the failure. Here, the image processing unit 600 divides the entire inspection area (the area photographed by the first camera and the second camera) of the inspection object for each area. In the present embodiment, a first region including a plating region and a coverlay (C / L) region, and a second region including a solder resist (SR) region and an overcoating (O / C) region are divided. For example, the first region and the second region may be distinguished by other criteria (such as color or material of the region) in addition to the inspection region for each item of the inspection object.

The image processor 600 selects and inspects an image corresponding to the first region from the first image captured by the first camera, and selects only an image corresponding to the second region from the second image captured by the second camera. Inspect At this time, there are two types of reference data to be compared using a design standard and a good substrate data.

3 is a flowchart for explaining an appearance inspection method, and FIG. 4 is a diagram for comparing first and second images of inspection areas for each item.

3 and 4, in the appearance inspection method according to the present invention, the image processing unit 600 includes the first region and the first inspection region (the region photographed by the first camera and the second camera) of the inspection object. It is divided into two areas (S10).

The first camera 310 of the first imaging member 300 photographs the entire area of the inspection object 10 using the first illumination, and the second camera 410 of the second imaging member 400 is the second camera. The entire area of the inspection object 10 is photographed using the illumination (S20). The first image acquired by the first camera 310 and the second image acquired by the second camera 410 are images of the imaging region of the same inspection object.

The first image acquired by the first camera 310 and the second image acquired by the second camera 410 are provided to the image processor 600, and the image processor 600 corresponds to the first area in the first image. Determining whether there is a defect by using the image corresponding to the plating area and the coverlay (C / L) area, and in the solder resist (SR) area and the overcoating (O / C) area corresponding to the second area in the second image. It is determined whether there is a defect with the corresponding image (S30).

As shown in FIG. 3, the inspection of the coverlay area and the plating area is performed with the first image because the first image obtained by the first camera 310 is clearer than the second image obtained by the second camera 410. In addition, the inspection of the solder resist area is performed with the second image because the second image obtained by the second camera 410 is clearer than the first image obtained by the first camera 310. Finally, the image processing unit 600 integrates the two test results to determine whether or not the payment (S40).

As such, the appearance inspection method of the present invention obtains an image using illuminations specialized for each region, and inspects for defects using only the image of the region optimized in the obtained images, thereby improving inspection reliability as well as inspection speed. You can.

In this embodiment, two cameras are used as a basic configuration, but a color camera may be additionally applied as necessary.

The present invention is a device for performing the final appearance inspection on the inspection object, the characteristics of this final appearance inspection equipment is basically to replace the existing visual inspection is inexpensive but fast inspection speed is very important. Therefore, in the present invention, the inspection object is photographed by varying the illumination wavelength used in the first camera 310 and the second camera 410, and the first image captured by the first camera 310 is the first image of the inspection object. The area may be inspected, and the second image captured by the second camera 410 may inspect the second area of the inspection object, thereby improving inspection reliability as well as inspection speed.

On the other hand, the present invention can be variously modified and take various forms in the appearance inspection apparatus and method consisting of the above configuration. It is to be understood, however, that the present invention is not limited to the specific forms referred to in the above description, but rather includes all modifications, equivalents and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

1 is a diagram illustrating an example of an inspection object, which is a flexible printed circuit board, divided into inspection areas for each item.

Figure 2 is a schematic diagram showing the main configuration of the appearance inspection system according to an embodiment of the present invention.

3 is a flowchart for explaining the appearance inspection method.

4 is a diagram for comparing first and second images of inspection areas for each item.

Explanation of symbols on the main parts of the drawings

100: stage

200: inspection unit

300: first photographing member

400: second recording member

600: image processing unit

Claims (19)

In the visual inspection system: A stage on which the test object is placed; Including an inspection unit for inspecting an inspection object placed on the stage; The inspection unit A first photographing member having a first camera to photograph an object to be inspected by using a first light and the first light; A second photographing member having a second camera for photographing an object to be inspected using a second light and the second light; A moving member which moves the first photographing member and the second photographing member together such that the first camera and the second camera continuously photograph the inspection object in line units; And An image processor for inspecting a first region in a first image provided from the first camera and a second region in a second image provided from the second camera to determine whether there is a defect; The first image and the second image is an image of the entire inspection area of the same inspection object, wherein the first region and the second region is a visual inspection system, characterized in that different from each other on the inspection object. The method of claim 1, The first lighting and the second lighting is a visual inspection system, characterized in that different types of lighting. The method of claim 1, The first lighting is coaxial fall lighting, The second illumination is a visual inspection system, characterized in that the focusing light. The method of claim 1, The first lighting Is a light with a red wavelength, The second lighting Appearance inspection system, characterized in that the illumination having a green wavelength. 5. The method of claim 4, The first and second lighting is a visual inspection system, characterized in that the LED light or a metal halide light equipped with a color filter. delete In the external inspection method of the inspection object: Simultaneously moving a first photographing member having a first illumination and a first camera and a second photographing member having a second illumination and a second camera, and acquiring a first image of the inspection object using the first photographing member; Obtaining a second image of the inspection object by using the second photographing member; Determining whether the first image is defective in the first region of the inspection object, and determining whether the second region is defective in the second image of the inspection object; The first image and the second image is an image of the entire inspection region of the same inspection object, the first region and the second region is a different region from the inspection object, And the first camera and the second camera acquire the first image and the second image by continuously photographing the inspection object in line units. The method of claim 7, wherein Appearance inspection method, characterized in that the first region and the second region overlap with each other. The method of claim 7, wherein And the first region and the second region do not overlap with each other. delete delete The method according to any one of claims 7 to 9, The first image and the second image is a visual inspection method, characterized in that the image of different resolution. The method according to any one of claims 7 to 9, And the first area and the second area are divided into inspection areas for each item of the inspection object. delete delete The method according to any one of claims 7 to 9, The first camera is photographed using coaxial fall light, and the second camera is photographed using condensed light. The method according to any one of claims 7 to 9, The first camera is photographed using the LED light having a red wavelength, The second camera is a visual inspection method characterized in that the image is taken using the LED light having a green wavelength. delete The method according to any one of claims 7 to 9, The first area includes a cover layer area among inspection areas for each item of the inspection object. And the second region includes a plating region and a solder resist (SR) region among inspection regions for each item of the inspection object.

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