JP2006017726A - Lighting system for inspecting micropattern of printed circuit board, automatic optical inspection system equipped with the same, and its inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system for inspecting a micropattern of a printed circuit board, to provide an automatic optical inspection system equipped with the same, and to provide its inspection method. <P>SOLUTION: The lighting system with which the automatic optical inspection system is equipped, comprises; at least one first light source which outputs reflection light centered on a flat surface section in a printed circuit board pattern; a beam splitter which receives/outputs the reflection light from the first light source to the printed circuit board and receives/outputs light reflected from the printed circuit board to an image sensor; at least one second light source which outputs reflection light centered on an edge section of the printed circuit board pattern; and a condenser lens which receives, condenses and outputs the reflection light from the second light source. When an image of the micropattern in the printed circuit board is acquired, levels of brightness and uniformity of the light are made high. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an automatic optical inspection system, and more particularly to an automatic optical inspection system including an illumination device having a plurality of light sources and a method for inspecting a micropattern of a printed circuit board thereof.

  Recently, printed circuit boards, which are one of the main materials used in liquid crystal display device drive integrated circuits (LCD Driver ICs), various semiconductor integrated circuits such as memories and LSIs, and micro products, include films and tapes. Manufactured in a form.

  Among such printed circuit boards, a circuit called a TAB (Tape Automatic Bonding) or COF (Chip On Film) board is frequently used. Patterns are formed on printed circuit boards in the form of films and tapes through manufacturing processes such as exposure, development, and etching, and these patterns are microminiaturized by gradually micronizing semiconductor devices. It is a fact that it is gradually impossible to inspect the defect. Therefore, accurate detection of printed circuit board pattern defects is an important factor for improving the productivity of semiconductor devices.

  Therefore, for these reasons, the demand for optical automatic inspection system for printed circuit boards has increased, and in the inspection of the appearance of printed circuit boards for optical automatic inspection system, pattern defects are not detected and defective products are defective. Detecting over detection is an important factor that has an absolute impact on system reliability.

  A general optical automatic inspection system performs optical inspection using a camera, an image sensor, or the like. At this time, the optical automatic inspection system performs an accurate inspection on the appearance of the printed circuit board by using an illumination device having transmission illumination and / or reflection illumination, and any one of various illumination devices. This selection is essential for accurate defect detection.

  For example, in inspecting a COF substrate among substrates in the form of films and tapes, the surface of the COF substrate has a very reflective surface similar to a mirror. The light is transmitted to the image sensor only when the incident angle of the light illuminated on the inspection object on the COF substrate is irradiated perpendicularly to the image sensor.

  For these reasons, while the pattern on the substrate is gradually miniaturized, due to a change in the method in the pattern formation technique, between the upper surface of the pattern including the planar portion and both ends of the pattern, that is, the edge portion. Despite the changes, problems arise for inspecting the printed circuit board under the same illumination conditions as existing ones. That is, unlike the upper surface of the pattern, both end faces of the pattern are not accurately reflected vertically by the image sensor, so that accurate video data cannot be obtained at both ends, making optimal inspection difficult. Such a phenomenon results in undetected and overdetected fatal defective items resulting from problems such as image distortion as the pattern on a printed circuit board in the form of a film or tape is miniaturized. It will affect the yield.

  The object of the present invention is to solve the above-mentioned problems, and it is a critical defect item that occurs through image distortion or the like due to the extremely fine pattern on the printed circuit board in the form of a film or tape. It is to realize an automatic optical inspection system and its inspection method for preventing undetected and overdetection.

  Another object of the present invention is to solve the above-mentioned problems, overcoming the limitation of brightness due to the form and characteristics on the pattern surface, and obtaining a more uniform surface brightness to obtain inspection reliability. It is an object of the present invention to provide an illuminating device for an automatic optical inspection system for improving productivity and productivity.

  According to one aspect of the present invention for achieving the above object, an automatic optical inspection system for optically inspecting a fine pattern of a printed circuit board includes a plurality of first and second light sources, And an illumination device for irradiating the printed circuit board with light from the second light source, and the irradiated light is reflected by the printed circuit board and receives the reflected light to obtain an image on the printed circuit board. An image sensor; and a video processing device that receives the video and determines whether the printed circuit board has a pattern defect. The illumination device is provided between the printed circuit board and the image sensor. Irradiation is performed centering on the planar portion of the pattern using one light source, and irradiation is performed centering on an edge portion of the pattern using the second light source.

  In a desirable form of this feature, in the lighting device, the first and second light sources are provided in one module. The illumination device includes a beam splitter that receives the light from the first light source, outputs the light to the printed circuit board, receives the reflected light from the printed circuit board, and outputs the light to the image sensor. Irradiation is performed centering on the plane portion. The illumination device includes the second light source and a condensing lens that collects and outputs the light from the second light source, and irradiates the edge portion of the pattern as a center. Here, it is preferable that the second light source is provided so that an incident angle of the light can be adjusted so that the second light source is irradiated around the edge portion. At this time, the incident angle of the second light source can be adjusted automatically or manually.

  In order to achieve the above object, according to another aspect of the present invention, there is provided an inspection method for an automatic optical inspection system including a plurality of first and second light sources for inspecting the quality of a printed circuit board. Irradiating the printed circuit board pattern with an optical signal from the first and second light sources, and a plane / edge portion of the printed circuit board pattern corresponding to the optical signal emitted from the first / second light source. Each of the method includes a step of acquiring video data, and a step of determining pass / fail of the printed circuit board from the acquired video data.

  In a preferred form of this feature, in the irradiating step, the first light source irradiates around the planar portion of the printed circuit board pattern, and the second light source irradiates around the edge portion. In this case, the method further includes adjusting an incident angle of the reflected light so that the second light source irradiates the edge portion as a center.

  According to another aspect of the present invention to achieve the above object, an illumination device provided in an automatic optical inspection system that inspects a printed circuit board using an image sensor is a plane of the printed circuit board pattern. At least one first light source for outputting reflected light to a portion; receiving the reflected light from the first light source; outputting the reflected light to the printed circuit board; receiving the reflected light from the printed circuit board; And at least one second light source that outputs reflected light to an edge portion of the printed circuit board pattern, and when obtaining an image of a fine pattern of the printed circuit board, the brightness uniformity is obtained. Improve.

  In a desirable form of this feature, the illumination device is provided in one module, and the second light source is provided so as to adjust an incident angle of the reflected light so that the edge portion is irradiated. The illumination device may further include a condenser lens that receives the reflected light from the second light source, collects the light, and outputs the condensed light.

  Therefore, according to the present invention, the automatic optical inspection system uses the first light source and the second light source, and the first light source is used in the surface inspection of the product in which the surface of the printed circuit board is reflective. Accurate video data for the edge region of the pattern that could not be obtained by the light source is acquired.

  The illuminating device of the present invention improves the brightness of each first light and the second light and the uniformity of the brightness during the optical inspection of each TAB and COF substrate, and in particular irradiates the inspection object of the second light. The optimum video data can be obtained by freely adjusting the angle to be performed.

  The automatic optical inspection system equipped with the illumination device of the present invention uses the first and second light sources to acquire image data for the plane portion and the edge portion of the printed circuit board pattern, thereby accurately inspecting the pattern. Inspection is possible, thereby preventing undetected and overdetected.

  In addition, since the lighting device is modularized and provided for two types of substrates having different surface features, optical inspection can be applied without replacing the lighting device. Thus, it becomes possible to inspect all of the TAB and COF substrates, thereby providing the operator with the convenience of equipment operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a configuration of a lighting device according to the present invention.

  Referring to FIG. 1, the illuminating device 110 is a device applied to an automatic optical inspection system 100 for inspecting a printed circuit board pattern for defects, and includes a number of first light sources 112, second light sources 116, and beam splitters. Beam Splitter 114. The lighting device 110 forms the first light source 112 and the second light source 116 in one module.

  Accordingly, the illuminating device 110 outputs light from the first light source 112 and irradiates the beam splitter 114 with light to illuminate the surface of the printed circuit board, that is, the plane portion of the pattern 104. At this time, the light vertically irradiated on the surface of the printed circuit board is vertically reflected from the beam splitter 114 and refracted again in the irradiated direction. The refracted light passes through the beam splitter 114 and transmits an image corresponding to the plane portion of the pattern 104 to the image sensor 102.

  The illumination device 110 outputs light from the second light source 116 to illuminate the surface of the printed circuit board, that is, the edge portion of the pattern 104. At this time, the incident angle of the light is adjusted automatically or manually so that the second light source 116 is irradiated around the edge portion of the pattern 104. Accordingly, the light output from the second light source 116 is irradiated around the edge portion of the printed circuit board pattern 104, and the image corresponding to the edge portion of the pattern 104 is transmitted to the image sensor 102 through the beam splitter 114 again. The

  Accordingly, the illuminating device 110 uses the first light source 112 and the second light source 116 to inspect the pattern in which the surface of the printed circuit board is reflective, and the light is obtained as a plane portion of the pattern. Irradiate to the edge part separately. Of course, the light irradiation area is not accurately divided due to the characteristics of the light. That is, the boundary area between the planar portion and the edge portion receives light from all of the first and second light sources. Therefore, in the present invention, the plane portion and the edge portion are separately described, but this is for clearly explaining the technical features of the present invention and is not intended to limit the technical idea.

  FIG. 2 is a cross-sectional view showing a configuration of an automatic optical inspection system including the illumination device shown in FIG.

  Referring to FIG. 2, the automatic optical inspection system 100 includes the illumination device 110 and is connected to the image processing device 120.

  As shown in FIG. 1, the illumination device 110 is provided between the printed circuit board 104 and the image sensor 102, and irradiates the planar portion (b) of the pattern 104 by using the first light source 112. Then, the second light source 116 is used to irradiate the edge portion (cb) of the pattern as the center. The plane portion (b) is an image region obtained using the first light source 112, and the edge portion is an image region obtained using the second light source 116, and the upper plane portion b is determined from the width (a) of the substrate. Excluded part. Therefore, according to the present invention, the image data of the image area (c) of the plane portion (b) and the edge portion (c-b) is acquired using the first light source 112 and the second light source 116.

  Specifically, the lighting device 110 includes the first light source 112 and the second light source 116 in one module, and receives the light from the first light source 112 and the first light source 112 to generate the printed circuit. A beam splitter 114 that outputs to the substrate 104, receives the reflected light from the printed circuit board 104, and outputs it to the image sensor 102, and irradiates the planar portion (b) of the pattern 104 as a center. To do. The second light source 116 and a condensing lens 118 that receives the light from the second light source 116 and collects and outputs the light are further provided, and the edge portion (cb) of the pattern 104 is centered. Irradiate. At this time, the second light source is controlled to be irradiated around the edge portion by a control device (for example, an image processing device) so that the incident angle of the light can be adjusted automatically or manually. .

  The video processing device 120 is provided in a typical computer system, programmable logic controller, or the like, and controls and processes various operations by automatic optical inspection. The video processing device 120 receives the video from the image sensor 102 and determines whether the pattern of the printed circuit board 104 is good.

  Here, the prior art illumination device (not shown) includes the first or second light source and irradiates the reflected illumination so that the surface of the printed circuit board pattern is reflected on a reflective surface like a mirror. In order to obtain the image data, the light vertically incident on the object to be inspected from the beam splitter is transmitted again to the image sensor through the beam splitter, and video data can be obtained only in the image area obtained by using one light source. . However, for the actual pattern inspection, as shown in FIG. 2, it is necessary to acquire and inspect the image data of the corresponding area using the first light source 112 and the second light source 116.

  Accordingly, the present invention utilizes the second light source 116 together with the first light source 112 to accurately acquire the first light source 112 by inspecting a printed circuit board whose product surface is reflective like a mirror. The second light source 116 is used to accurately acquire and inspect the image data of the pattern area, that is, the edge portion that could not be obtained.

  At this time, the angle adjustment of the second light source can be automatically or manually adjusted to obtain the brightness of the image data and the higher data of the edge portion of the pattern through the incident angle of the second light source 116. Of course, it is obvious to those skilled in the art that the second light source 116 is fixed by setting an accurate incident angle by design.

  Accordingly, the automatic optical inspection system 110 uses the first light source 112 and the second light source 116 to use the second light source 116 in the surface inspection of the product in which the surface of the printed circuit board 104 is reflective. Accurate video data for the edge region of the pattern 104 that could not be obtained at 112 can be acquired to accurately inspect the printed circuit board 104. Of course, it is obvious that the automatic optical inspection system 100 can inspect a printed circuit board having other properties (for example, a TAB substrate) using only the first light source 112 or the second light source 116.

  FIG. 3 is a diagram illustrating a pattern of a printed circuit board according to an embodiment of the present invention. FIGS. 4A and 4B are diagrams comparing brightness and uniformity of brightness of a specific measurement position of this pattern between the related art and the present invention. FIG.

  Referring to FIGS. 4A and 4B, the fine pattern of the printed circuit board, that is, the specific measurement position 130 shown in FIG. 3 is compared with the brightness of the image data acquired using the prior art, that is, only the first light source. A profile 132 indicating uniformity and a profile 134 according to the present invention are shown.

  The profile 132 in FIG. 4A is irregularly formed with brightness uniformity between about 200 and 250 levels, and the minimum value is also formed with the brightness below 200 levels. However, the profile 134 in FIG. It can be seen that brightness uniformity is formed very regularly between about 240 to 250 levels using the first light source 112 and the second light source 116, and the lowest part is formed at almost 240 levels or more even in brightness. .

  Therefore, comparing these two profiles 132 and 134, it can be seen that the brightness of the lighting device 110 of the present invention is improved by about 30% or more.

  Subsequently, FIG. 5 is a flowchart showing an inspection procedure of the optical inspection system including the illumination device of the present invention. This procedure is stored in a memory (not shown) of the video processing device 120 as a program executed by the video processing device 120.

  Referring to FIG. 5, the image processing apparatus 120 irradiates the printed circuit board 104 with light using the first light source 112 and the second light source 116 in step S150. At this time, the first light source 112 emits light around the planar portion of the printed circuit board pattern 104, and the second light source 116 emits light around the edge portion. Further, the incident angle of the reflected light is adjusted so that the second light source 116 irradiates around the edge portion.

  In step S152, the image data of the planar portion and the edge portion of the printed circuit board pattern 104 are acquired in response to the optical signals emitted from the first light source 112 and the second light source 116, respectively. In step S154, it is determined whether the printed circuit board pattern 104 is good or bad from the acquired video data.

  On the other hand, among the printed circuit boards in the form of films and tapes, there are TAB and COF boards, and the two types of boards have different features on the surface.

  First, if you look at the TAB substrate, it has a diffusing surface in which various surface angles are formed on the pattern surface and reacts mostly to light coming from various incident angles. Lighting that irradiates light through is used. However, in the COF substrate, as described above, the product surface is formed in a reflective surface like a mirror. Therefore, such a product has normally used an illuminating device (for example, an illuminating device using a beam splitter) in which an incident angle for irradiating an inspection object is formed perpendicular to the image sensor. However, in such an illuminating device, the pattern of the printed circuit board is miniaturized, which causes a problem that video data for a specific portion of the pattern cannot be accurately captured.

  In particular, when inspecting a COF substrate of a film or tape type substrate, the COF substrate has a very reflective surface similar to a mirror. Then, the light is transmitted to the image sensor only when the incident angle of the light illuminating the inspection object on the COF substrate is perpendicular to the image sensor. For this reason, when the pattern on the substrate is gradually miniaturized, it is possible to inspect the upper surface of the pattern, that is, the plane portion, and both end surfaces of the pattern, that is, the edge portion under the same existing illumination conditions. Since the images on the both end faces are transmitted to the image sensor differently from the image on the pattern surface, it is difficult to obtain the image data at both ends and the optimum inspection becomes difficult.

  Therefore, the present invention reduces the image loss at both ends of the substrate pattern where the product surface has a very reflective surface similar to a mirror, and the light source is used in a lighting device that illuminates light through a beam splitter. When shining light directly with a beam splitter, it becomes possible to improve the overall brightness of the light reflected by the inspection object due to the loss of light and passing through the image sensor. An optimal image can be obtained in the inspection of the printed circuit board in the form.

It is the perspective view which showed the structure of the illuminating device by this invention. It is sectional drawing which shows the structure of the automatic optical inspection system which comprises the illuminating device shown in FIG. FIG. 3 is a diagram illustrating a pattern of a printed circuit board according to an embodiment of the present invention. It is the figure which showed the brightness by the measurement position of the pattern shown in FIG. 3, and the uniformity of brightness compared. It is the figure which showed the brightness by the measurement position of the pattern shown in FIG. 3, and the uniformity of brightness compared. It is the flowchart which showed the test | inspection procedure of the optical test | inspection system which comprises the illuminating device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Automatic optical inspection system 102 Image sensor 104 Printed circuit board pattern 110 Illumination device 112 1st light source 114 Beam splitter 116 2nd light source 118 Condensing lens 120 Image processing apparatus 130 Measurement position

Claims (12)

In an automatic optical inspection system that optically inspects fine patterns on a printed circuit board,
An illuminating device comprising a plurality of first and second light sources, and irradiating the printed circuit board with light from the first and second light sources;
The irradiated light is reflected by the printed circuit board, and receives the reflected light to obtain an image for the printed circuit board; and
A video processing device that receives the video and determines whether or not the pattern of the printed circuit board is defective;
The illumination device is provided between the printed circuit board and the image sensor, irradiates around a plane portion of the pattern using the first light source, and uses the second light source to emit the pattern. An automatic optical inspection system characterized by irradiating around an edge portion. In the lighting device,
The automatic optical inspection system according to claim 1, wherein the first and second light sources are provided in one module. The lighting device includes:
A beam splitter for receiving the light from the first light source and outputting the light to the printed circuit board; receiving the reflected light from the printed circuit board and outputting the light to the image sensor; and centering the planar portion of the pattern The automatic optical inspection system according to claim 1, wherein the automatic optical inspection system is irradiated with light. The lighting device includes:
The automatic optical inspection system according to claim 3, further comprising a condensing lens that collects and outputs the light received from the second light source, and irradiates the edge portion of the pattern as a center. .   The automatic optical inspection system according to claim 1, wherein the second light source is provided so that an incident angle of the light can be adjusted so that the second light source is irradiated around the edge portion. In an inspection method of an automatic optical inspection system comprising a plurality of first and second light sources for inspecting the quality of a printed circuit board,
Irradiating the printed circuit board pattern with an optical signal from the first and second light sources;
Acquiring image data of a plane / edge portion of the printed circuit board pattern corresponding to the optical signal emitted from the first / second light source,
An inspection method for an automatic optical inspection system, comprising: determining whether the printed circuit board is good or bad from the acquired video data. In the irradiation step,
The inspection of the automatic optical inspection system according to claim 6, wherein the first light source irradiates around the planar portion of the printed circuit board pattern, and the second light source irradiates around the edge portion. Method. The step of irradiating comprises:
The inspection method for an automatic optical inspection system according to claim 6, further comprising adjusting an incident angle of the reflected light so that the second light source irradiates the edge portion as a center. In an illumination device provided in an automatic optical inspection system that inspects a printed circuit board using an image sensor,
At least one first light source that outputs reflected light to a planar portion of the printed circuit board pattern;
A beam splitter that receives the reflected light from the first light source and outputs the reflected light to the printed circuit board, receives the reflected light from the printed circuit board, and outputs the reflected light to the image sensor;
And at least one second light source that outputs reflected light centering on an edge portion of the printed circuit board pattern, and improves brightness uniformity when acquiring an image of a fine pattern of the printed circuit board. Lighting device for automatic optical inspection system. The lighting device includes:
The illumination device of the automatic optical inspection system according to claim 9, further comprising a condensing lens that receives the reflected light from the second light source and collects and outputs the condensed light.   The illumination device of the automatic optical inspection system according to claim 9 or 10, wherein the illumination device is provided in one module. The illumination of the automatic optical inspection system according to claim 9 or 10, wherein the second light source is configured to be able to adjust an incident angle of the reflected light so that the second light source is irradiated around the edge portion. apparatus.