KR20090126066A - Apparatus for illuminating for inspection of printed circuit board and apparatus for inspecting the same - Google Patents

Abstract

PURPOSE: An apparatus for illuminating for inspection of a printed circuit board and an apparatus for inspecting the same are provided to increase test speed by detecting a defect and a foreign material by taking a picture of a target one time. CONSTITUTION: In an apparatus for illuminating for inspection of a printed circuit board and an apparatus for inspecting the same, a first lighting part(30) radiates a light within 0~45 degrees around a first axis on the surface of a device under test. The first lighting part radiates a light within 45~90 degrees around a first axis on the surface of a device under test. A first reflecting mirror(32) reflects the light on the surface of the device under test by a first angle. A second reflecting mirror(42) reflects the light on the surface of the device under test by a second angle.

Description

Apparatus for illuminating for inspection of printed circuit board and apparatus for inspecting the same}

The present invention relates to a lighting device and a circuit board inspection device having the same, and more particularly, to check light on a surface of a material to be inspected for defects. The present invention relates to a lighting device to be irradiated and a circuit board inspection device having the same.

A printed circuit board (PCB) is an electronic component that serves to electrically connect electronic components, supply power, and the like, and mechanically fix the electronic components. Chip on film (COF), tape automatic bonding (TAB), and board on chip (BOC) are also types of PCBs. The inspection of PCB patterns in various flexible or rigid circuit board fields such as COF, TAB, BOC, or displays is very important. Because of the miniaturization of electronic information devices, a lot of fine and complex circuit patterns are formed on the rigid or flexible PCB inside the device, because a defective pattern causes the device to malfunction.

Therefore, after the circuit pattern is formed on the PCB, the PCB pattern inspection is performed to determine whether the surface state of the PCB pattern is defective. In recent years, machine vision technology is used to photograph the surface state of a PCB pattern with a camera, and process and analyze the captured image to determine whether a patch is defective.

The defect of the PCB pattern may be a defect of the pattern (open), short (short), some bit (pit), protrusion, etc. of the pattern. PCB pattern checks should be performed to avoid under kills that mislead these defects as good. In addition, the actual PCB pattern is not defective, due to foreign matters may be mistaken for good products. Therefore, PCB pattern inspection should be performed to avoid over killing of a good product as a defective product. In addition, PCB patterns should be inspected as soon as possible.

For this purpose, the role of the lighting device for inspection is important. In the past, most inspection apparatuses processed images photographed under the illumination of the first configuration and images photographed under the illumination of the second configuration, so that the inspection time was long and the inspection apparatus became complicated.

The present invention can distinguish circuit pattern areas, defective areas, foreign material areas, and space areas shown on the inspection target surface in order to reduce the time required for inspection of the PCB pattern, and to perform accurate PCB pattern inspection by preventing overcheck and unchecked. To provide a circuit board inspection lighting device having a unique brightness range and a circuit board inspection device having the same.

In order to solve the above problems, the present invention is disposed on the photographing means side for taking an image of the inspection object, the first angle greater than 0 ° and less than 45 ° with respect to the first axis which is the axis of the subject light incident on the imaging means First illumination means configured to emit light irradiated onto the surface of the inspection object; And second illumination means disposed on the photographing means side with respect to the inspection object and configured to emit light irradiated onto the surface of the inspection object at a second angle greater than 45 ° and less than 90 ° with respect to the first axis. Disclosed is a lighting device for inspecting a circuit board including;

By configuring both the first lighting means and the second lighting means as front lights, it is possible to minimize the size of the space occupied by the entire lighting device, thereby improving workability by increasing the working space between the inspection object and the lighting device. have.

Further, by providing the bright field front lighting by the first lighting means and the dark field front lighting by the second lighting means, the brightness of the circuit pattern region P, the brightness of the defective region, and the foreign matter region D are provided. Since the brightness of the, and the brightness of the space area (S) and the like are each distinguished by a unique brightness, there is an advantage that can reduce the difficulty of the inspection algorithm used in the inspection apparatus.

The first lighting means includes a first reflecting mirror reflecting the light such that the light emitted from the first light source and the first light source is irradiated onto the surface of the inspection object at the first angle with respect to the first axis. The second lighting means may include a second reflecting mirror reflecting the light so that the light emitted from the second light source and the second light source is irradiated onto the surface of the inspection object at the second angle with respect to the first axis.

The first lighting means comprises two said first light sources and two said first reflecting mirrors, wherein one pair and the other pair of the first light source and the first reflecting mirror are symmetrically with respect to said first axis. And the second lighting means comprises two said second light sources and two said second reflecting mirrors, wherein one pair and the other of said second light source and said second reflecting mirror are mutually relative to said first axis. It is arranged symmetrically.

The first angle may be an angle between 1 ° and 5 °, and the second angle may be an angle between 50 ° and 80 °.

The arrangement of the first and second illumination means may be adjusted such that the amount of light from the first and second illumination means is maximum at the lens focal length of the imaging means.

The test object may be a chip on film (COF).

In addition, according to another aspect of the present invention, the present invention is a circuit board inspection lighting device; And photographing means disposed on an opposite side of the object to be inspected based on the lighting device and having light incident on the surface of the object to be emitted from the illumination device and indicating an image of the subject irradiated to the surface of the object to be inspected. .

In the lighting apparatus for inspecting a circuit board according to an embodiment of the present invention, the circuit pattern region, the defective region, the foreign substance region, and the space region shown on the inspection target surface may be irradiated with light so as to have a unique brightness region.

Therefore, it is possible to detect defects in the circuit pattern and the presence of foreign matters by one imaging, thereby increasing the inspection speed. In addition, it is possible to perform accurate PCB pattern inspection by preventing overcheck and unchecked. In addition, the volume of the lighting device can be minimized to increase the working space between the lighting device and the inspection object.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. 1 is a perspective view showing a part of an inspection object. The object to be inspected may be a printed circuit board (PCB) including a flexible circuit board (FPCB) such as a COF as a product requiring a defect inspection. COF is a form in which a layer of PI (polyimide) is laminated on a PET layer, and there is a defect of open (6) in one circuit pattern (4b), and foreign matter (5) such as dust on the other circuit pattern (4a). ) Exists.

FIG. 2A shows an apparatus (hereinafter, referred to as coaxial illumination) configured to irradiate light from an axis of the subject light incident on the camera 10 (hereinafter referred to as a camera optical axis) and a front surface of the coaxial, 2B is a surface image of the PCB pattern of FIG. 1 seen under coaxial illumination. Referring to FIG. 2A, a half mirror 13 is disposed on the camera optical axis. The light rays emitted from the light source 15 are reflected through the half mirror 13 and then irradiated onto the surface of the inspection object 1 along the camera optical axis L. That is, under coaxial illumination, the inspection object is illuminated on the same line as the camera optical axis L. FIG. On the other hand, the light (hereinafter referred to as the subject light) representing the image of the inspection subject 1 as the subject passes through the half mirror and is incident on the lens 11 of the camera as it is.

When the coaxial illumination is used in this way, the surface of the inspection object of FIG. 1 is viewed as shown in FIG. 2B. When the coaxial illumination is used, the circuit pattern region P and the foreign substance region D are bright and the space region S is dark. Since the broken portion O of the circuit pattern region P is shown to have a brightness similar to that of the space region S, it is easy to detect a breakage of the pattern, but the foreign material region D has a brightness similar to that of the circuit pattern region P. It is not easy to detect the foreign matter 5 on the circuit pattern 3 because it appears. That is, under kill may occur with respect to the foreign matter 5 on the circuit pattern 3. In addition, when the foreign matter 5 extends beyond the circuit pattern 3, overkill may occur in which a part of the circuit pattern 3 appears to protrude. In addition, in the case of such an illumination device, the brightness of the illumination and the accuracy of focus are lowered according to the performance of the half mirror 13, for example, the quality and thickness of the half mirror 13. In addition, it is difficult to apply when the reflection is severe depending on the surface state of the inspection object (1).

FIG. 3A shows an illumination device (hereinafter referred to as reflective illumination) configured to irradiate light from the side front face at an angle with the camera optical axis, and FIG. 3B is a surface image of the PCB pattern of FIG. 1 seen under a reflective illumination device. to be. Referring to FIG. 3A, light sources 15 are disposed at both sides of the camera optical axis L, respectively. Light rays emitted from the light source 15 are irradiated obliquely on the surface of the inspection object 1. Under such reflected illumination, the surface reflection of the inspection object 1 is less than the surface reflection of the inspection object 1 in coaxial illumination. The subject light irradiated onto the surface of the inspection object 1 is incident on the lens 11 of the camera 10.

When the reflected light is used in this way, the surface of the inspection object of FIG. 1 is viewed as shown in FIG. 3B. Under the reflected illumination, the circuit pattern region P looks bright and the space region S and the foreign matter region D look dark. Since the broken portion O of the circuit pattern region P is shown to have a brightness similar to that of the space region S, it is easy to detect the breakage of the circuit pattern region P, but the foreign matter region D is also the space region S. Because it looks similar to), it is often mistaken for a broken pattern. That is, overchecking may occur with respect to the foreign matter 5 on the circuit pattern 3.

FIG. 4A shows an illumination device (hereinafter referred to as transmission illumination) configured to irradiate light from the back side of the PCB pattern, and FIG. 4B shows a surface image of the PCB pattern of FIG. 1 seen under transmission illumination. Referring to FIG. 4A, the light sources 15 are disposed on the side opposite to the side where the camera 10 is disposed on the surface of the inspection object 1. The light sources 15 are arranged on both sides as well as coaxial, so that light rays are irradiated on opposite sides of the inspection object 1 at opposite coaxial and sides of the camera 10. Under such transmission illumination, since the illumination is concentrated at one point of the inspection object, the amount of light is increased. Subject light emitted through the object 1 after being irradiated to the opposite surface of the object 1 is incident on the camera 10.

In this way, when the illumination is used, the surface of the inspection object of FIG. 1 is seen as shown in FIG. 4B. Under the transmission illumination, the circuit pattern region P and the foreign substance region D appear dark and the space region S looks relatively bright. Since the broken portion O of the circuit pattern region P is shown to have a brightness similar to that of the space region S, it is easy to detect the breakage of the circuit pattern 3, but the foreign matter region D is the circuit pattern region P. It is difficult to detect the foreign matter (5) because it looks similar to the brightness. That is, the unchecked can occur with respect to the foreign matter 5 in the pattern. In addition, when the foreign matter 5 extends beyond the circuit pattern 3, overexamination may occur where a part of the circuit pattern 3 appears to protrude.

FIG. 5A shows the flow of light under front illumination (hereinafter referred to as bright field front illumination) according to an example, and FIG. 5B shows the surface image of the PCB pattern of FIG. 1 seen under bright field front illumination of FIG. 5A. The light is irradiated from the same front as the side where the camera 10 is disposed, and the light is irradiated at the same or similar angle as the coaxial illumination in FIG. 2A, so that a bright field image is obtained as in FIG. 5B. Accordingly, it can be seen that the brightness of the circuit pattern region P and the foreign substance region D, which are portions protruding toward the camera 10, is bright. Under the bright field front illumination, since the foreign matter area D and the circuit pattern area P have similar brightness, it is difficult to detect the foreign matter 5, but the breakage of the circuit pattern 3 can be easily detected. have.

FIG. 6A shows the flow of light under front illumination (hereinafter referred to as dark field front illumination) according to another example, and FIG. 6B shows the surface image of the PCB of FIG. 1 seen under dark field front illumination of FIG. 6A. The light is irradiated at a larger angle (an angle greater than 45 ° relative to the camera's optical axis) with respect to the camera optical axis, similar to the reflected illumination in FIG. 3A, resulting in a dark field image rather than a bright field image. That is, the circuit pattern region P and the space region S are dark overall, and only the foreign matter region D is bright. Thus, dark field front illumination is useful for inspecting only the foreign material 5 itself, but not for inspecting other important parts such as the circuit pattern 3.

By analyzing the advantages and disadvantages of the above-described lighting devices, the present invention provides a circuit pattern region P, a foreign substance region D, and a space region S shown in the inspection object 1 to have a distinctive brightness region. It provides a lighting device that is an optimal combination of bright field front lighting and dark field front lighting. 7 is a view schematically showing a lighting device according to an embodiment of the present invention.

Referring to FIG. 7, the lighting device 20 according to the embodiment of the present invention includes a first lighting means 30 and a second lighting means 40. The first lighting means 30 is disposed symmetrically with respect to the optical axis L of the photographing means 10 such as a camera, and is disposed on the side, that is, in front of the photographing means 10. The first lighting means 30 on each side includes a first light source 31 and a first reflection mirror 32. The first reflecting mirror 32 of the first lighting means 30 has the inspection object (a light beam emitted from the first light source 31 at a first angle θ1 smaller than 45 ° with respect to the optical axis L of the imaging means). It is positioned and oriented to irradiate the surface of 1).

Here, since the first angle θ1, which is an angle formed between the center of the optical axis of the lens of the photographing means and the irradiation angle, is smaller than 45 °, a bright field image is provided. The first angle θ1 may vary depending on the characteristics of the inspection target. When the inspection object is COF, the first angle θ1 may be an angle between 1 and 10 degrees, preferably between 1 and 5 degrees. The illumination by the first illumination means 30 thus constitutes bright field front illumination, such as the coaxial illumination described above. However, unlike the coaxial illumination using the half mirror, since the first lighting means 30 uses the reflection mirror 32, the light quantity of the light beam is not reduced, so that the light quantity of the illumination is concentrated where the focal point of the lens coincides with the focal point of the lens. This allows for brighter images than coaxial lighting. Therefore, defects in patterns such as breaks can be easily detected.

On the other hand, within the range in which the first reflection mirror 32 does not interfere with the light of the subject incident on the photographing means 10, the light rays exiting from the first light source 31 and reflected through the first reflection mirror 32 are The first reflecting mirror 32 is positioned and oriented so as to be almost similar to the optical axis L of the imaging means.

The second lighting means 40 is disposed symmetrically with respect to the optical axis L of the photographing means, and is disposed on the side, that is, in front of the photographing means 10. The second lighting means 40 on each side includes a second light source 41 and a second reflection mirror 42. The second reflecting mirror 42 of the second illuminating means 40 is inspected at a second angle θ _{2 in which} the light rays emitted from the second light source 41 are larger than 45 ° with respect to the optical axis L of the photographing means. It is positioned and oriented to irradiate the surface of (1).

Here, since the second angle θ ₂ , which is an angle formed between the center of the optical axis of the lens of the photographing means and the irradiation angle, is larger than 45 °, a dark field image is provided. The second angle θ ₂ may vary depending on the characteristics of the inspection object. When the test object is COF, the second angle θ ₂ may be an angle between 46 and 85 °, preferably between 50 and 80 °. The illumination by the second illumination means 40 thus constitutes dark field front illumination. At this time, the optical axis of the illumination of the second illumination means 40 can be matched with the focal point of the lens, thereby obtaining a brighter foreign matter (bad) image.

On the other hand, the second light source 42 and the second reflection mirror 41 are positioned and oriented to obtain a dark field image as in FIG. 6B. The illumination by the second illumination means 40 thus constitutes the dark field front illumination described above. Therefore, the brightness of the foreign matter region is increased as compared with the circuit pattern region, and thus foreign matter on the circuit pattern can be easily detected.

FIG. 8 is a view schematically showing a path of light rays emitted under the lighting apparatus shown in FIG. 7. Light rays indicated by solid lines mean light rays from the front light of the bright field, and light rays indicated by dashed lines mean light rays from the front light of the dark field.

FIG. 9 is a surface image of the PCB of FIG. 1 seen under the lighting device of the present invention shown in FIG. 7. Referring to the drawing, the circuit pattern area P and the foreign matter area D are brightly displayed and the space area S is dark due to the light rays from the front light of the bright field, and the light rays from the front light of the dark field are shown. As a result, the foreign material area D is displayed brighter, and the circuit pattern area P and the space area S are darker. Therefore, when viewed comprehensively, the space area S is dark, the circuit pattern area P and the foreign material area D are brightly displayed, and the brightness of the foreign material area D is greatest.

In order to determine the brightness in each of the circuit pattern region P, the foreign substance region D, and the space region S existing on the surface to be inspected, the surface of the COF having the foreign substance under the lighting apparatus according to the embodiment of the present invention is used. The actual picture taken is shown in FIG. In addition, FIG. 10 illustrates brightness graphs in the circuit pattern region P, the foreign substance region D, and the space region S when viewed along the line C in the photographed test target surface image. Comparing the absolute brightness value in each area, the brightness value of the foreign matter area D is about twice as large as the brightness value of the circuit pattern area P, and the brightness value of the circuit pattern area P is the space area S. ) Is several times greater than the brightness value. By simply analyzing one image of the surface of the inspection object 1 using the lighting device 20 according to the embodiment of the present invention, defects in a circuit pattern and presence of foreign substances can be detected at a time. . This speeds up production and reduces the manufacturing costs of lighting and inspection devices. In addition, since the brightness of the circuit pattern area P, the brightness of the defective area, the brightness of the foreign material area D, and the brightness of the space area S are each divided into unique brightness, the difficulty of the inspection algorithm used in the inspection device. There is also an advantage to lower.

The lighting apparatus according to the embodiment of the present invention described so far may be applied when the inspection target is COF. In addition, those skilled in the art can be applied not only to flexible printed circuit boards including COF but also to rigid printed circuit boards by changing the arrangement of the respective light sources and the reflecting mirrors in the above-described first and second lighting means within the ordinary creative scope. I will understand that.

Industrial Applicability The present invention can be used in industries in which defect inspection of a circuit board or the like is required.

1 is a perspective view showing a part of an inspection object.

FIG. 2A is a schematic view of a lighting device configured to irradiate light from a front surface coaxial with a camera optical axis. FIG.

FIG. 2B shows a surface image of the PCB of FIG. 1 seen under the lighting device shown in FIG. 2A.

FIG. 3A is a schematic view of a lighting device configured to irradiate light from a side front surface at an angle with a camera optical axis.

FIG. 3B shows a surface image of the PCB of FIG. 1 seen under the lighting device shown in FIG. 3A.

4A is a view schematically showing a lighting device configured to irradiate light from a rear surface of a PCB pattern.

FIG. 4B shows a surface image of the PCB of FIG. 1 seen under the illumination device shown in FIG. 4A.

5A is a view showing a flow of light rays under bright field front illumination according to an example.

FIG. 5B shows a surface image of the PCB of FIG. 1 seen under bright field front illumination shown in FIG. 5A.

6A is a diagram showing the flow of light under dark field front illumination according to another example.

FIG. 6B shows a surface image of the PCB of FIG. 1 as seen under the dark field front illumination shown in FIG. 6A.

7 is a view schematically showing a lighting device according to an embodiment of the present invention.

FIG. 8 is a view schematically showing a path of light rays emitted under the lighting apparatus shown in FIG. 7.

FIG. 9 shows a surface image of the PCB of FIG. 1 as seen under the lighting apparatus shown in FIG. 7.

FIG. 10 is a photograph showing images of COF and foreign matter actually photographed under a lighting apparatus according to an embodiment of the present invention, and brightness values in respective regions.

Claims (7)

Disposed on the photographing means side for photographing the image of the examination subject, and irradiating the light irradiated onto the surface of the examination subject at a first angle greater than 0 ° and less than 45 ° with respect to the first axis, which is the axis of the subject light incident on the photographing means; First lighting means configured to emit; And Second illumination means disposed on the photographing means side with respect to the inspection object and configured to emit light irradiated onto the surface of the inspection object at a second angle greater than 45 ° and less than 90 ° with respect to the first axis; Circuit board inspection lighting device comprising a. According to claim 1, The first lighting means includes a first reflecting mirror reflecting the light such that the light emitted from the first light source and the first light source is irradiated onto the surface of the inspection object at the first angle with respect to the first axis, The second illuminating means includes a circuit board including a second light source and a second reflecting mirror reflecting the light such that the light from the second light source is irradiated onto the surface of the inspection object at the second angle with respect to the first axis. Inspection lighting device. The method of claim 2, The first lighting means comprises two said first light sources and two said first reflecting mirrors, wherein one pair and the other pair of the first light source and the first reflecting mirror are symmetrically with respect to said first axis. Will be placed, The second lighting means comprises two said second light sources and two said second reflecting mirrors, wherein one pair and the other of said second light source and said second reflecting mirror are symmetrically with respect to said first axis. A lighting device for inspecting a circuit board disposed. According to claim 1, And the first angle is between 1 ° and 5 °. According to claim 1, And the second angle is between 50 ° and 80 °. According to claim 1, The inspection object is a circuit board inspection lighting device COF (chip on film). A lighting device according to any one of claims 1 to 6; And And photographing means disposed on an opposite side of the object to be inspected based on the lighting device, and the light emitting means representing the image of the subject irradiated from the lighting device to the surface of the object to be inspected.

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