JP2009122089A - Apparatus and method for optically inspecting printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for optically inspecting a printed circuit board. <P>SOLUTION: The present invention relates to an apparatus and method for optically inspecting a printed circuit board, and the method includes the steps of: irradiating a printed circuit board with light in an infrared band; acquiring image data of the printed circuit board; and detecting the presence or absence of a foreign matter on the printed circuit board from the image data. The apparatus and method for optically inspecting a printed circuit board make it possible to use light in an infrared band to reduce excessive detection of products that are judged to be defective due to a nonconducting foreign matter, and make it possible to simultaneously carry out an electrical circuit pattern inspection and an appearance inspection, thus enabling an improvement in speed of inspection. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical inspection apparatus and method, and more specifically, an optical inspection apparatus for a printed circuit board that selectively detects only conductive foreign matters in a circuit pattern and appearance inspection of a printed circuit board in order to minimize overdetection. And its method.

  Printed circuit boards, which are one of the main materials used in the manufacture of various semiconductor devices such as driving integrated circuits and memories for liquid crystal display devices, are becoming increasingly smaller in size and weight, and have become films and tapes. ) Type flexible printed circuit board (Flexible Printed Circuit Board) is often used. The flexible printed circuit board includes, for example, a TAB (Tape Automatic Bonding), COF (Chip On Film) board, and the like, and a fine pattern is formed on the board through exposure, development, an etching process, and the like. Recently, among the defects to be detected in such automatic optical inspection, for example, dust, metal residues, and fibers are many problems such as short circuit of pattern components in the space between the pattern components and deterioration of product functions. Is causing.

  Therefore, the manufacturer of the flexible printed circuit board performs the core inspection for the appearance inspection of the plating area of the product, the solder resist area, the area where the semiconductor wafer is mounted (inner lead), etc. in the inspection before the product shipment. It is divided into items. Therefore, effective inspection of inspection items is the key to productivity and quality control for manufacturers of flexible printed circuit boards for semiconductor IC manufacturing.

  Currently, manufacturers of automatic inspection devices, for example, AOI (Automated Optical Inspection) system and AVI (Automated Visual Inspection) system, determine what is actually defective in the optical inspection of flexible printed circuit boards. Various technologies have been developed in order to minimize the undetected phenomenon and the over-detection phenomenon (for example, a non-defective product is determined to be a defective product) due to non-defective foreign matter and dust.

  Various technologies related to an automatic inspection apparatus and method for inspecting a circuit pattern and an appearance of a flexible printed circuit board for which a patent application has been filed by the applicant of the present invention have been disclosed. Such technology minimizes an undetected phenomenon in which a defective product is detected as a non-defective product and an over-detection phenomenon in which a non-defective product is detected as a defective product during automatic optical (or vision) inspection.

  For example, Patent Document 1 “Automatic Optical Inspection System with Illumination Device and Inspection Method”, Patent Document 2 “Optical Inspection System and Method for Preventing Overdetection of Flexible Printed Circuit Board”, Patent Document 3 "System and method for preventing over-detection in visual inspection of film and tape type printed circuit board" and Patent Document 4 "Automatic optical inspection for real-time monitoring to prevent over-detection of printed circuit board" System and its processing method ".

  In such a technique, in the circuit pattern and appearance inspection of the flexible printed circuit board, video data is acquired using a visible light band illumination device to detect dents, protrusions, short circuits, etc., and the acquired video data Is compared with the reference data to determine whether it is good or bad. However, when optical inspection is performed using an illumination device in the visible light band, it is determined whether the portion determined to be defective is a conductive (metallic) foreign material or a non-conductive (nonmetallic) foreign material. I can't do it.

  This is because the pattern components are not electrically connected between the pattern components of the video data, i.e., the non-conductive foreign matter remaining in the spatial component. This causes an overdetection phenomenon that is determined to be defective.

In particular, between the pattern components (that is, between the leads) inside the region (that is, the solder resist region) where the insulating component (for example, solder resist) is applied on the surface of the pattern component. The foreign matter present in the film cannot be discriminated with the naked eye because it exists inside the insulating component layer. Therefore, when using an illumination device in the visible light band, for example, when image data is acquired by irradiating the insulating component layer with light in the visible light band, the entire insulating component layer appears dark. There is a problem that accurate inspection cannot be performed, for example, the pattern component cannot be distinguished from the spatial component.
Korean Patent Application Publication No. 2006-984 Korean Patent No. 0661910 Korean Patent Application Publication No. 2006-43462 Korean Patent No. 06739797

  The present invention was created to solve the above-mentioned problems, and its purpose is to detect overdetection of defective products that occur because it is difficult to distinguish between conductive foreign matter and non-conductive foreign matter. An object of the present invention is to provide a printed circuit board optical inspection apparatus and method capable of preventing and processing a circuit pattern inspection and an appearance inspection of a printed circuit board at the same time.

  To achieve the above object, an optical inspection apparatus according to the present invention is generated by a support member that supports a printed circuit board, an illumination device that irradiates the printed circuit board with light in the infrared band, and light in the infrared band. A camera that acquires video data for the printed circuit board; and a video processing procedure that detects whether or not foreign matter exists between the pattern components of the printed circuit board from the video data.

  Here, the lighting device may include an infrared light emitting diode.

  The illumination device may include an infrared lamp.

  Further, the camera can be an infrared camera.

  In addition, the illumination device may be positioned on the opposite side of the camera with respect to the support member so that transmitted light can be used.

  Further, the illumination device may be located on the same side as the camera with respect to the support member so that reflected light can be used.

  According to another aspect of the invention, a method for automatically optically inspecting at least one printed circuit board is provided. According to this method, the step of irradiating the printed circuit board with light in the infrared band, the step of acquiring video data of the printed circuit board, and the step of detecting the presence or absence of foreign matter on the printed circuit board from the video data; ,including.

  Here, the step of irradiating light in the infrared band can irradiate transmitted light in the infrared band.

  Further, the step of irradiating light in the infrared band can irradiate reflected light in the infrared band.

  Furthermore, the step of detecting the presence / absence of the foreign matter can detect the presence / absence of a metallic foreign matter.

  The step of detecting the presence or absence of the foreign matter may be detecting the presence or absence of a metallic foreign matter in a space between the patterns formed on the printed circuit board.

  Further, the printed circuit board may be a circuit pattern formed and before a solder resist is applied.

  In addition, the printed circuit board may be one after a circuit pattern is formed and a solder resist is applied.

  Further, the printed circuit board may be a flexible printed circuit board.

  As described above, the printed circuit board optical inspection apparatus of the present invention can select and detect only conductive foreign matters by using an illumination device that emits light in the infrared band.

  Therefore, in the circuit pattern and appearance inspection, non-defective products due to non-conductive foreign matters can be excluded from detection targets, and overdetection can be minimized.

  In addition, in order to minimize the phenomenon that the yield decreases by processing multiple inspection steps in the printed circuit board manufacturing process, electrical circuit patterns and appearance inspection are performed by using an infrared band illumination device. Can be performed simultaneously.

  Embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed to be limited to the following embodiments. This embodiment is provided in order to more fully explain the present invention to those who have average knowledge in the field to which the present invention belongs. Accordingly, the shapes of elements in the drawings are exaggerated to emphasize a clearer description.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8 of the accompanying drawings.

  1 and 2 are diagrams showing the configuration of an optical inspection apparatus for inspecting a printed circuit board according to the present invention.

  As shown in FIGS. 1 and 2, the optical inspection device 100 of the present invention includes a support member 101, an illumination device 102, a camera 104, a lens 106, and an image processing device 108.

  The support member 101 supports the printed circuit board 110 for optical inspection of the present invention, and the illumination device 102 includes an infrared light emitting diode or an infrared lamp, and irradiates the printed circuit board 110 with light in the infrared band.

  At this time, when the illuminating device 102 uses transmitted light, the illuminating device 102 is preferably located on the opposite side of the camera 104 with respect to the support member 101 as shown in FIG. As shown in FIG. 2, the illumination device 102 is preferably located on the same side as the camera 104 with respect to the support member 101. In particular, according to the present invention, a plating region (114 in FIG. 3) where a circuit pattern is plated from video data, a solder resist region where a pattern component and a spatial component are formed inside, and a solder resist is formed on the top. (118 in FIG. 3) is used to acquire video data using the illumination device 102 that emits an optical signal in the infrared band for electrical circuit pattern inspection and visual inspection.

  The lens 106 and the camera 104 receive an optical signal in the infrared band through the printed circuit board 110 and acquire video data. For example, in order to acquire image data using the illumination device 102 in the infrared band, the image data is acquired using an infrared lens, or the infrared band has a longer focal length than the visible light band. When is used, the lens focal length is made longer. Further, since the infrared lens is a lens that makes the visible light band and the infrared light band have the same focal length, there is no need to adjust the focal length. At this time, it goes without saying that the camera 140 and the lens 106 that receives light in the infrared band can be substituted for the infrared camera.

  The video processing device 108 detects foreign matter existing between the pattern components of the printed circuit board 110 from the video data. However, since infrared rays are used, non-conductive foreign matter is not detected and only conductive foreign matter is selected. Detected. That is, the non-conductive foreign matter is naturally determined as a good product. Accordingly, the electrical circuit pattern inspection and the appearance inspection can be simultaneously performed using the video data acquired from the light in the infrared band by the video processing device 108.

  Here, the configuration of the printed circuit board 110 for performing electrical circuit pattern inspection and appearance inspection using the optical inspection apparatus 100 of the present invention will be described with reference to FIGS.

  As shown in FIGS. 3 to 5, the printed circuit board 110 is formed by forming circuit patterns 114 and 116 on the base substrate 112 and then applying plating and solder resist on the circuit patterns 114 and 116 in the manufacturing process. It is manufactured and includes a plating region 114, a solder resist region 118, and an inner lead region 113 on which a semiconductor chip or the like is mounted. The application region 114 is composed of a plated pattern component 114a and a space component 114b between the pattern component 114a, and a solder resist region 118 is formed on the upper portion to protect the plated pattern component 116a and the space component 116b. A solder resist 118a is applied.

  In the solder resist region 118, foreign matter exists in the internal space 116b between the pattern component 116a and the pattern component 116a in the same manner as the plating region 114. Such foreign matter includes conductive foreign matter that causes a short circuit of the product. This causes a fatal problem in product performance.

  However, since the foreign matter existing inside the solder resist region 118 is wrapped with the solder resist component, as shown in FIG. 7, when irradiated with light in the visible light band, the non-defective foreign matter is obtained from the acquired video data 10. It is difficult to distinguish whether it is a non-conductive foreign material (ie, a non-conductive foreign material) or a defective foreign material (ie, a conductive foreign material).

  On the other hand, the optical inspection apparatus 100 of the present invention can automatically and selectively discriminate only conductive foreign substances among such foreign substances using the illumination device 102 in the infrared band.

  The optical inspection method according to the present invention will be described below.

  FIG. 6 is a flowchart showing the inspection procedure of the optical inspection method according to the present invention. This procedure is processed in an electrical inspection after the circuit pattern is plated on the printed circuit board, or in an appearance inspection after the solder resist is coded on the top.

  As shown in FIG. 6, the printed circuit board is irradiated with light in the infrared band in step S150, and video data on the printed circuit board is acquired in step S152. In this case, image data can be obtained by irradiating infrared band transmitted light or infrared band reflected light with infrared band light.

  In step S154, the presence or absence of foreign matter on the printed circuit board, particularly metallic foreign matter, is detected from the video data and determined. That is, the presence / absence of metallic foreign matter in the space component 114b between the pattern components 114a formed on the printed circuit board or in the internal space 116b between the pattern component 116a and the pattern component 116a in the solder resist region 118 is detected.

  At this time, the printed circuit board may be in a state after the circuit pattern is formed and before the solder resist is applied, or after the circuit pattern is formed and after the solder resist is applied. Unlike the conventional technique in which it was difficult to detect the presence or absence of metallic foreign matter after the solder resist was applied, according to the present invention, in any case, the presence or absence of metallic foreign matter was irradiated with light in the infrared band. Can be easily detected.

  If it is determined in step S154 that there is a foreign substance in the video data, the process proceeds to step S156, where it is determined that the foreign substance is not a non-conductive foreign substance, and only the conductive foreign substance is easily selected and detected by the naked eye. In step S160, it is determined as a defective product. That is, the spatial component and the non-conductive foreign matter are similar in brightness, so that it is difficult to distinguish them, but when only the conductive foreign matter is present, it is clearly visible.

  On the other hand, if it is determined that there is no foreign matter in the video data, the process proceeds to step S158, where it is determined that there is no foreign matter or only non-conductive foreign matter is present, so that it is determined as a non-defective product in step S162.

  Therefore, what appears to be a foreign substance on the video data can be determined to be a conductive foreign substance naturally, and can eventually be determined to be a defective product.

  For example, FIG. 7 is a photograph showing image data of a printed circuit board acquired by using a visible light band illumination device in a general automatic inspection apparatus, and FIG. 8 is an infrared optical band image obtained by automatic optical inspection according to the present invention. It is a photograph which shows the video data of the printed circuit board acquired using the illuminating device.

  Among such printed circuit boards, products such as TAB and COF used as substrates for driving integrated circuits (LCD DRIVER ICs) of liquid crystal display panels have undergone production processes such as exposure and development processes, and circuit patterns and spaces. An electrical circuit pattern inspection is performed in a state in which is formed. As a subsequent process, plating on the pattern and a process of applying an insulating component such as a solder resist, etc. are performed to finally inspect the finished product of the printed circuit board. In particular, in such a circuit pattern or appearance inspection, video data is acquired using an illumination device that emits light in the visible light band (transmitted light or reflected light).

  From the acquired video data 10, defects such as protrusions and shorts are detected between the pattern component 12 and the pattern component 12, that is, in the spatial component 14. Try to analyze such defective products. In some cases, the patternability (conductivity, metallicity) may be poor, or there may be a nonconductive foreign matter component 16. However, such non-conductive foreign materials do not cause a problem in the performance of the product and are removed in the subsequent plating and cleaning processes, and therefore should be determined as good in the pattern inspection process. . However, if the image data 10 of transmitted light (or reflected light) is acquired using an illumination device in the visible light band as in the past, such foreign matter 16 is conductive (metallic) or non-conductive. It is not possible to determine whether the material is non-metallic (non-metallic). As a result, an over-detection phenomenon in which a non-defective product is determined as a defective product is increased, the yield of the manufacturer is lowered, and it is difficult to ensure cost competitiveness.

  In addition, a pattern inspection process is performed, and a final appearance inspection is performed in the state of a finished product through plating, a solder resist process, and the like. At this time, foreign matter also exists in the space between the pattern component inside the solder resist, but such foreign matter includes conductive foreign matter that causes a short circuit in the product. However, it causes a fatal problem in the performance of the product.

  However, since the foreign matter existing in the space region between the pattern component and the pattern component existing inside such a solder resist region is wrapped in the solder resist component, when irradiating light in a general visible light band, It is difficult to distinguish between non-defective foreign substances, that is, non-conductive foreign substances, and defective foreign substances, that is, conductive foreign substances.

  Therefore, according to the present invention, non-defective foreign matter and defective foreign matter are detected from video data by irradiating light in an infrared band having a long wavelength instead of the conventional visible light band and performing circuit pattern and appearance inspection of the printed circuit board. Can be easily distinguished, thereby minimizing over-detection.

  That is, as shown in FIGS. 7 and 8, regarding the same printed circuit board, in the video data 10 acquired with light in the visible light band, the non-conductive foreign matter 16 is clearly reflected, so that it can be determined as a defective product. As in the present invention, in the video data 120 acquired with light in the infrared band, it is difficult to identify the non-conductive foreign material 126, so that it is not detected and is determined to be a good product.

  For this reason, first, image data is acquired by irradiating the printed circuit board with light using an illumination device that irradiates light in the infrared band. At this time, the video data 120 is divided into a pattern component 122 and a spatial component 124 below the insulating component layer, but the spatial component 122 appears bright and the pattern component 124 appears dark.

  If the non-conductive foreign material 126 is present on the spatial component 124, the brightness is slightly lower than the brightness of the spatial component formed on average, so that the spatial component 124 and the non-conductive as shown in FIG. It is almost indistinguishable from the foreign material 16.

  Therefore, according to the present invention, when the foreign matter 126 exists on such a spatial component 124, the insulating component layer 118, which cannot be inspected by a conventional optical inspection apparatus, is compared with the brightness of the pattern component or the spatial component. Only metallic foreign matters on the internal space component 116b can be easily selected and detected. At this time, it can be detected with reference to the level change, area, etc. of the illuminance meter of the foreign matter.

  The configuration and operation of the printed circuit board optical inspection apparatus and method according to the present invention have been described above with reference to the detailed description and the drawings. Various changes and modifications can be made without departing from the technical idea of the present invention.

It is a figure which shows the structure of the optical inspection apparatus which test | inspects the printed circuit board by embodiment of this invention. It is a figure which shows the structure of the optical inspection apparatus which test | inspects the printed circuit board by embodiment of this invention. It is a figure which shows the plating area | region and soldering resist area | region of a printed circuit board. It is sectional drawing which shows the plating area | region and soldering resist area | region of FIG. It is a top view which shows the pattern component and space component of the soldering resist area | region of FIG. It is a flowchart which shows the test | inspection procedure of the optical test method by this invention. It is a photograph which shows the video data of the printed circuit board discriminated as defective due to non-conductive foreign substances in a general automatic optical inspection. 4 is a photograph showing image data of a printed circuit board that is determined as a non-defective product by detecting a non-conductive foreign object by automatic optical inspection according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical inspection apparatus 102 Illumination apparatus 104 Camera 106 Lens 108 Image processing apparatus 110 Printed circuit board 112 Base board 113 Internal lead area 114 Plating area 118 Solder resist area

Claims (14)

A support member for supporting the printed circuit board;
An illumination device for irradiating the printed circuit board with light in an infrared band; and
A camera for acquiring video data for the printed circuit board generated by the light in the infrared band;
An optical inspection apparatus for a printed circuit board, comprising: an image processing treatment for detecting whether or not a foreign substance exists between pattern components of the printed circuit board from the image data.   The optical inspection apparatus for a printed circuit board according to claim 1, wherein the illumination apparatus includes an infrared light emitting diode.   The optical inspection apparatus for a printed circuit board according to claim 1, wherein the illumination device includes an infrared lamp.   The optical inspection apparatus for a printed circuit board according to any one of claims 1 to 3, wherein the camera is an infrared camera.   4. The printed circuit according to claim 1, wherein the illumination device is located on the opposite side of the camera with respect to the support member so that transmitted light can be used. 5. Optical inspection device for substrates.   4. The printed circuit according to claim 1, wherein the illumination device is positioned on the same side as the camera with respect to the support member so that reflected light can be used. 5. Optical inspection device for substrates. Irradiating the printed circuit board with light in the infrared band; and
Obtaining video data of the printed circuit board;
Detecting the presence or absence of foreign matter on the printed circuit board from the video data. 5. An optical inspection method for a printed circuit board, comprising:   8. The optical inspection method for a printed circuit board according to claim 7, wherein the step of irradiating light in the infrared band irradiates transmitted light in the infrared band.   8. The optical inspection method for a printed circuit board according to claim 7, wherein the step of irradiating the infrared band light irradiates reflected light of the infrared band.   The optical inspection method for a printed circuit board according to claim 7, wherein the step of detecting the presence or absence of the foreign matter detects the presence or absence of a metallic foreign matter.   11. The optical inspection of a printed circuit board according to claim 10, wherein the step of detecting the presence or absence of the foreign matter detects the presence or absence of a metallic foreign matter in a space between patterns formed on the printed circuit board. Method.   The optical inspection method for a printed circuit board according to any one of claims 7 to 11, wherein the printed circuit board is in a state before a solder resist is applied after the circuit pattern is formed.   The optical inspection method for a printed circuit board according to any one of claims 7 to 11, wherein the printed circuit board is in a state after a circuit pattern is formed and a solder resist is applied.   The optical inspection method for a printed circuit board according to any one of claims 7 to 11, wherein the printed circuit board is a flexible printed circuit board.