Inspection device and inspection method

Abstract

To determine a defect type of the defect in detail.SOLUTION: An inspection device 1 includes an image acquisition unit 2 that acquires visible light images of a substrate using visible light and infrared light images of the substrate using infrared light, an inspection unit 41 that performs inspection processing on each of the visible light images and the infrared light images to detect defects in the substrate, and a defect type determination unit 42 that determines a defect type of the defect based on the inspection processing results of the visible light images and the infrared light images for the defects detected by the inspection unit 41, as well as area types of the area where the defects exist. This makes it possible to determine the defect type of the defect in detail.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a technique for inspecting a substrate.

Background Art

[0002] Conventionally, an inspection apparatus has been used that captures an image of a printed circuit board on which a pattern is formed to obtain an image, and detects defects using the image. For example, in the inspection apparatus of Patent Document 1, a visible light image of a substrate is obtained using visible light, and an infrared light image of the substrate is obtained using infrared light. By comparing the visible light image and the infrared light image, defects on the surface of the substrate are detected. Further, the visible light image is an image obtained by synthesizing a plurality of types of color component images, and an image obtained by synthesizing the infrared light image and at least one color component image is displayed on a display unit. Also, in the inspection apparatus of Patent Document 2, a visible light image of an inspection target is obtained using visible light, and an infrared light image of the inspection target is obtained using infrared light. By comparing the visible light image and the infrared light image, foreign matter that is imaged in the visible light image but not in the infrared light image is determined to be a material having permeability to infrared light, and foreign matter imaged in both the visible light image and the infrared light image is determined to be, for example, a metal or a metal compound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, in the apparatus of Patent Document 2, it is determined whether foreign matter on the surface of an inspection target is a metal (including metal compounds). However, since there are various types of defects, a technique for more detailed determination of the type of defect is required.

[0005] The present invention has been made in view of the above problems, and aims to determine in detail the type of defect.

Means for Solving the Problems

[0006] Aspect 1 of the present invention is an inspection apparatus for inspecting a substrate, including an image acquisition unit that acquires a visible light image of the substrate using visible light and acquires an infrared light image of the substrate using infrared light, an inspection unit that executes inspection processing on each of the visible light image and the infrared light image to detect defects on the substrate, and a defect type determination unit that determines the defect type of the defect based on the inspection processing result of the visible light image for the defect detected by the inspection unit, the inspection processing result of the infrared light image, and the region type of the region where the defect exists.

[0007] Aspect 2 of the present invention is the inspection apparatus of Aspect 1, wherein the inspection unit executes the inspection processing using an inspection data set indicating position information and region type of a plurality of inspection regions on the substrate.

[0008] Aspect 3 of the present invention is the inspection apparatus of Aspect 1 (which may be Aspect 1 or 2), wherein the inspection unit executes a plurality of types of inspections as the inspection processing on each of the visible light image and the infrared light image, the inspection processing result of the visible light image includes the results of a plurality of types of inspections, and the inspection processing result of the infrared light image includes the results of a plurality of types of inspections.

[0009] Aspect 4 of the present invention is the inspection apparatus of Aspect 1 (which may be any one of Aspects 1 to 3), wherein the inspection processing result of the visible light image and / or the inspection processing result of the infrared light image distinguish between bright defects and dark defects.

[0010] Aspect 5 of the present invention is an inspection apparatus according to Aspect 1 (which may be any one of Aspects 1 to 4), wherein the defect type determination unit stores a defect determination matrix in which a plurality of combinations of the region type of the defect existence region, the inspection processing result of the visible light image, and the inspection processing result of the infrared light image are associated with a plurality of defect types.

[0011] Aspect 6 of the present invention is an inspection apparatus according to Aspect 1 (which may be any one of Aspects 1 to 5), further comprising a display control unit that causes the display unit to display the defect detected by the inspection unit, wherein in the defect type determination unit, some of the plurality of defect types are specified as serious defects, and the display control unit causes the display unit to display the defects that are serious defects in a distinguishable manner from other defects.

[0012] Aspect 7 of the present invention is an inspection apparatus according to Aspect 1 (which may be any one of Aspects 1 to 6), further comprising a carry-out mechanism that conveys the substrate after imaging by the image acquisition unit to a predetermined carry-out position, wherein in the defect type determination unit, some of the plurality of defect types are specified as serious defects, and the carry-out mechanism conveys the substrate including the defects that are serious defects to a position different from other substrates.

[0013] Aspect 8 of the present invention is an inspection apparatus according to any one of Aspects 1 to 7, wherein the substrate is a printed circuit board, a solder resist layer is provided on the surface of the substrate, and the inspection unit detects defects in the lower layer of the solder resist layer using the infrared light image.

[0014] Aspect 9 of the present invention is an inspection apparatus for inspecting a substrate, comprising an image acquisition unit that acquires a visible light image of the substrate using visible light and an infrared light image of the substrate using infrared light, an inspection unit that performs an inspection process on each of the visible light image and the infrared light image to detect a defect of the substrate, and a defect type determination unit that determines a defect type of the defect based on an inspection process result of the visible light image and an inspection process result of the infrared light image for the defect detected by the inspection unit, wherein the substrate is a printed circuit board, a solder resist layer is provided on a surface of the substrate, and the inspection process result of the infrared light image includes a detection result of a defect in a lower layer of the solder resist layer.

[0015] Aspect 10 of the present invention is an inspection method for inspecting a substrate, comprising: a) a step of acquiring a visible light image of the substrate using visible light and an infrared light image of the substrate using infrared light; b) a step of performing an inspection process on each of the visible light image and the infrared light image to detect a defect of the substrate; and c) a step of determining a defect type of the defect based on an inspection process result of the visible light image and an inspection process result of the infrared light image for the defect detected in the step b), and based on a region type of an existence region of the defect.

[0016] Aspect 11 of the present invention is the inspection method of Aspect 10, wherein in the step c), a defect determination matrix in which a plurality of combinations of a region type of an existence region of a defect, an inspection process result of a visible light image, and an inspection process result of an infrared light image are associated with a plurality of defect types is used.

[0017] Aspect 12 of the present invention is the inspection method of Aspect 10 or 11, wherein among a plurality of defect types, some defect types are specified as serious defects, and a different process is performed on a substrate including a defect that is a serious defect from other substrates.

Advantages of the Invention

[0018] According to the present invention, it is possible to determine in detail the defect type of a defect.

Brief Description of the Drawings

[0019]

Figure 1

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Figure 9A

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Figure 10A

Figure 10B

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Figure 11

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Figure 14

Embodiments for Carrying Out the Invention

[0020] FIG. 1 is a diagram showing an inspection apparatus 1 according to an embodiment of the present invention. The inspection apparatus 1 is an apparatus for inspecting a printed circuit board 9, and in one example, it is used for the final appearance inspection of the printed circuit board 9. The inspection apparatus 1 may be used for inspections other than the final appearance inspection. The inspection apparatus 1 includes an image acquisition unit 2, a loading mechanism (not shown), an unloading mechanism 11, and a computer 3. The computer 3 is responsible for overall control of the inspection apparatus 1 and realizes the functions of an inspection arithmetic unit 4 (see FIG. 3) described later.

[0021] The image acquisition unit 2 includes an imaging unit 20, a stage 24, and a stage moving mechanism 25. The imaging unit 20 includes a visible light emitting unit 211, an infrared light emitting unit 212, an optical system 22, and an imaging unit 23. The visible light emitting unit 211 emits visible light (wavelength 400 nm to 700 nm). The visible light emitting unit 211 in FIG. 1 emits white light including the entire wavelength region of visible light, but may emit light including only a part of the wavelength region of visible light. The infrared light emitting unit 212 emits infrared light (wavelength 700 nm to 1 mm). A preferable infrared light emitting unit 212 emits infrared light including a wavelength region of 800 nm or more. The optical system 22 includes lenses, a half mirror, and the like. The imaging unit 23 has an image sensor such as a CCD sensor or a CMOS sensor. The image acquired by the imaging unit 23 is a color image including a plurality of color components (typically RGB), but depending on the design of the inspection apparatus 1, it may be an image of some color components.

[0022] When the visible light emitting unit 211 emits visible light, the optical system 22 guides the visible light to the printed circuit board 9 on the stage 24 and makes the reflected light of the visible light from the printed circuit board 9 incident on the imaging unit 23. Thereby, in the imaging unit 23, an image of the printed circuit board 9 using visible light (hereinafter referred to as a "visible light image") is acquired. The visible light image is a white light image. When the visible light emitting unit 211 emits infrared light, the optical system 22 guides the infrared light to the printed circuit board 9 and makes the reflected light of the infrared light from the printed circuit board 9 incident on the imaging unit 23. Thereby, in the imaging unit 23, an image of the printed circuit board 9 using infrared light (hereinafter referred to as an "infrared light image") is acquired.

[0023] The stage 24 holds the printed circuit board 9. Typically, the printed circuit board 9 is held on the stage 24 in a horizontal posture. The stage moving mechanism 25 has a ball screw, a guide rail, a motor, etc., and moves the stage 24 in a substantially horizontal direction along the main surface of the printed circuit board 9. In an example of the image acquisition unit 2, the imaging unit 23 is a line sensor and simultaneously acquires an image of a linear region extending in one direction on the main surface of the printed circuit board 9. The stage moving mechanism 25 reciprocates the stage 24 in a direction substantially perpendicular to the linear region. In one of the forward and return paths of the stage 24, a visible light image of the printed circuit board 9 is acquired, and in the other, an infrared light image of the printed circuit board 9 is acquired.

[0024] The visible light image and the infrared light image may be acquired by various methods. For example, an imaging unit for the visible light image and an imaging unit for the infrared light image may be provided separately, and both images may be acquired simultaneously using a filter or the like. Also, the visible light image and the infrared light image may be acquired by moving the imaging unit 20 relative to the printed circuit board 9. A mechanism for inverting the printed circuit board 9 may be provided in the image acquisition unit 2, and the visible light image and the infrared light image may be acquired for both main surfaces of the printed circuit board 9.

[0025] The loading mechanism conveys the printed circuit board 9 arranged at the loading position and places it on the stage 24. The configuration of the loading mechanism is, for example, the same as that of the unloading mechanism 11 described later. The unloading mechanism 11 may also serve as the loading mechanism. The unloading mechanism 11 includes a suction unit 111, a lifting unit 112, and a moving mechanism 113. The suction unit 111 holds the printed circuit board 9 by suction. The lifting unit 112 has, for example, an air cylinder or a motor, etc., and moves the suction unit 111 in a substantially vertical direction. The moving mechanism 113 moves the lifting unit 112 in a substantially horizontal direction.

[0026] In the inspection apparatus 1, when the visible light image and the infrared light image of the printed circuit board 9 are acquired, the printed circuit board 9 is moved by the stage movement mechanism 25 below the suction unit 111 waiting in the vicinity of the imaging unit 20. The suction unit 111 is lowered by the elevating unit 112 to suck and hold the printed circuit board 9, and then the suction unit 111 is raised. Thereafter, the printed circuit board 9 together with the suction unit 111 and the elevating unit 112 is moved in a direction away from the stage 24 by the movement mechanism 113.

[0027] A carry-out position P1 is provided on the movement path by the movement mechanism 113. The carry-out position P1 is, for example, a stocker that houses the printed circuit board 9 (the same applies to the auxiliary carry-out position P2 described later). When the printed circuit board 9 reaches above the carry-out position P1 by the movement mechanism 113, the suction unit 111 is lowered by the elevating unit 112. Then, by releasing the suction and holding of the printed circuit board 9 by the suction unit 111, the printed circuit board 9 is placed on the carry-out position P1. In the example of FIG. 1, an auxiliary carry-out position P2 is also provided on the movement path by the movement mechanism 113, and the carry-out mechanism 11 can convey the printed circuit board 9 to the carry-out position P1 or the auxiliary carry-out position P2.

[0028] Figure 2 is a diagram showing the configuration of computer 3. Computer 3 has the configuration of a general computer system including a CPU 31, a ROM 32, a RAM 33, a storage device 34, a display unit (display) 35, an input unit 36, a reading device 37, a communication unit 38, a GPU 39, and a bus 30. The CPU 31 performs various arithmetic processes. The GPU 39 performs various arithmetic processes related to image processing and the like. The ROM 32 stores a basic program. The RAM 33 and the storage device 34 store various information. The display unit 35 displays various information such as images. The input unit 36 includes a keyboard 36a and a mouse 36b that receive input from an operator. The reading device 37 reads information from a computer-readable recording medium M1 such as an optical disk, a magnetic disk, a magneto-optical disk, or a memory card. The communication unit 38 transmits and receives signals to and from the image acquisition unit 2 and the like. The bus 30 is a signal circuit that connects the CPU 31, the GPU 39, the ROM 32, the RAM 33, the storage device 34, the display unit 35, the input unit 36, the reading device 37, and the communication unit 38. In computer 3, a touch panel may be provided, and the input unit 36 and the display unit 35 may be realized by the touch panel.

[0029] In computer 3, a program 340 is previously read from the recording medium M1 via the reading device 37 and stored in the storage device 34. The program 340 may be stored in the storage device 34 via a network. The CPU 31 and the GPU 39 execute arithmetic processes while using the RAM 33 and the storage device 34 according to the program 340. The CPU 31 and the GPU 39 function as arithmetic units in computer 3. Other configurations that function as arithmetic units may be adopted in addition to the CPU 31 and the GPU 39.

[0030] FIG. 3 is a block diagram showing a functional configuration realized by the computer 3. In the inspection apparatus 1, the computer 3 executes arithmetic processing and the like according to the program 340, whereby the inspection arithmetic unit 4 (the functional configuration surrounded by a broken line in FIG. 3) is realized. That is, the CPU 31, GPU 39, ROM 32, RAM 33, storage device 34, etc. of the computer 3 realize the inspection arithmetic unit 4. All or part of the inspection arithmetic unit 4 may be realized by a dedicated electric circuit, or each function may be realized by an individual program. Also, the inspection arithmetic unit 4 may be realized by a plurality of computers. In FIG. 3, the image acquisition unit 2 and the display unit 35 are also shown in blocks.

[0031] The inspection arithmetic unit 4 includes an inspection unit 41, a defect type determination unit 42, and a display control unit 43. The inspection unit 41 executes inspection processing on each of the visible light image and the infrared light image input from the image acquisition unit 2, and detects defects on the printed circuit board 9 from each image. The inspection unit 41 also stores the inspection data set 411 used for the inspection processing. The defect type determination unit 42 determines the defect type of the defect based on the inspection processing result of the visible light image, the inspection processing result of the infrared light image, etc. The defect type determination unit 42 also stores the defect determination matrix 421 used for the determination of the defect type. The display control unit 43 causes the display unit 35 to display the defects and the like detected by the inspection unit 41.

[0032] Here, the schematic structure of the printed circuit board 9 and the region type of the inspection region on the printed circuit board 9 will be described. FIG. 4 is a cross-sectional view showing the printed circuit board 9. In an example of the printed circuit board 9, a wiring pattern 912 made of a metal such as copper is formed on a resin base material 911, and further, a solder resist (SR) layer 913 that covers most of the base material 911 and the wiring pattern 912 is formed. As will be described later, characters, symbols, etc. are printed on a part of the solder resist layer 913 with silk ink.

[0033] FIG. 5 is a diagram for explaining the region types of the inspection region. The left side of FIG. 5 shows a visible light image 71 showing a part of the printed circuit board 9, the center shows a LUT (look-up table) 49 used for extracting the inspection regions of each region type, and the right side shows the inspection regions of a plurality of region types in the part of the printed circuit board 9 shown by the visible light image 71.

[0034] The plurality of region types in this processing example include a plating portion 95 which is a part of the exposed wiring pattern 912 (since it is mainly a pad, it is also called a pad portion), a first SR portion 96 which is a portion of the solder resist layer 913 where the lower layer is the wiring pattern 912, a second SR portion 97 which is a portion of the solder resist layer 913 that directly contacts the base material 911, and a silk portion 98 which is characters, symbols, etc. printed on the solder resist layer 913. The colors of the plating portion 95, the first SR portion 96, the second SR portion 97, and the silk portion 98 are different from each other, and the LUT 49 indicates the region (range in the color space) of each region type in the RGB color space. The LUT 49 is stored in the inspection operation unit 4.

[0035] In the inspection operation unit 4, for example, a master image is obtained by averaging a plurality of visible light images acquired from a plurality of printed circuit boards 9. Subsequently, by referring to the LUT 49 using the color at each position of the master image, the region type of the position is specified. A set of positions of the same region type (typically, regions that are continuous with each other) is determined as one inspection region of the region type. The white region in the uppermost image on the right side of FIG. 5 indicates the inspection region of the plating portion 95, the gray region in the second image from the top indicates the inspection region of the first SR portion 96. The black region in the third image from the top indicates the inspection region of the second SR portion 97, and the white region in the lowermost image indicates the inspection region of the silk portion 98.

[0036] The above inspection data set 411 indicates the position information (including size) and region types of a plurality of inspection regions on the printed circuit board 9. As will be described later, in the inspection unit 41, a plurality of types of inspections are performed as inspection processes for each inspection region, and the inspection data set 411 also includes the thresholds for various types of inspections for each region type. The inspection data set 411 may further include various parameters used for the inspection (for example, the size of the filter when performing filter processing, etc.). The content of the defect determination matrix 421 will be described later.

[0037] Here, the problems in the visible light image 71 will be described. FIGS. 6A and 6B are diagrams showing the visible light image 71, and each visible light image 71 includes a defect 79 detected by the inspection process of the inspection unit 41. The defect 79 in the left visible light image 71 of FIG. 6A is a disconnection of the wiring pattern 912 in the first SR portion 96 (hereinafter referred to as "pattern disconnection"), and it is a serious defect that does not allow the shipment of the printed circuit board 9 including the defect 79. On the other hand, the defect 79 in the right visible light image 71 is ink attached on the first SR portion 96 (hereinafter referred to as "ink attachment on the pattern"), and it is a minor defect that can be removed by wiping. In the visible light image 71, since the defects 79 on the left and right sides of FIG. 6A appear to have the same color tone, it is difficult to distinguish between pattern disconnection and ink attachment on the pattern.

[0038] The defect 79 in the left visible light image 71 of FIG. 6B is an indentation in the plating portion 95 (since most of the plating portion 95 is a pad, hereinafter referred to as "pad indentation"), and it is a serious defect that does not allow the shipment of the printed circuit board 9 including the defect 79. On the other hand, the defect 79 in the right visible light image 71 is a solder resist attached on the plating portion 95 (hereinafter referred to as "SR attachment on the pad"), and it is a minor defect that can be removed by wiping. In the visible light image 71, since the defects 79 on the left and right sides of FIG. 6B appear to have the same color tone, it is difficult to distinguish between pad indentation and SR attachment on the pad. If an operator only checks the visible light image 71, there is a possibility that a serious defect is judged as a minor defect and the printed circuit board 9 including the serious defect is shipped.

[0039] Next, the features of the infrared light image will be described. FIG. 7 is a diagram showing the results of measuring the first SR portion 96 and the second SR portion 97 of the printed circuit board 9 using a hyperspectral camera. The line L1 in FIG. 7 shows the measurement result for the first SR portion 96, and the line L2 shows the measurement result for the second SR portion 97. As shown in FIG. 7, the contrast between the first SR portion 96 and the second SR portion 97 when irradiated with light having a wavelength of 800 nm or more (infrared light) is dramatically improved compared to the case of irradiating with visible light (wavelength 400 nm to 700 nm). Actually, by using infrared light, it is possible to obtain an image in which the solder resist layer 913 is made approximately transparent.

[0040] FIG. 8 is a diagram showing a plurality of visible light images 71 and a plurality of infrared light images 72. The upper part of FIG. 8 is the visible light image 71, and the lower part of FIG. 8 is the infrared light image 72 showing the same region as the visible light image 71. Also from FIG. 8, it can be seen that in the infrared light image 72, an image in which the solder resist layer 913 (or partially adhered solder resist) is made approximately transparent can be obtained. Therefore, in the inspection process using the infrared light image 72, it is possible to detect defects in the lower layer of the solder resist layer 913.

[0041] Next, the outline of the inspection process in the inspection unit 41 will be described. As described above, in the inspection unit 41, a plurality of types of inspections are executed as inspection processes for each inspection region. In this processing example, since the same type of inspection is performed on the visible light image 71 and the infrared light image 72, in the following description, the visible light image 71 and the infrared light image 72 are collectively referred to as "target images". FIG. 9A is a diagram showing a target image, and FIG. 9B is a diagram showing a master image corresponding to the target image.

[0042] When the target image is the visible light image 71, the master image is obtained, for example, by averaging a plurality of visible light images 71 showing the same area of a plurality of printed circuit boards 9. When the target image is the infrared light image 72, the master image is obtained, for example, by averaging a plurality of infrared light images 72 showing the same area of a plurality of printed circuit boards 9. In this processing example, comparison inspection, foreign matter inspection, and unevenness inspection are performed as a plurality of types of inspections. In the following description, attention is paid to the plating portion 95 (mainly pads), but the same inspections are also performed on the first SR portion 96, the second SR portion 97, and the silk portion 98. Other types of inspections may be performed as inspection processing. Also, different inspections may be performed on the visible light image 71 and the infrared light image 72, or different inspections may be performed on inspection regions of a plurality of region types.

[0043] FIG. 10A is a diagram for explaining the comparison inspection. In the comparison inspection of the plating portion 95, the shape of the plating portion 95 in the target image of FIG. 9A is compared with the shape of the plating portion 95 in the master image of FIG. 9B. In one example, an image showing the difference between the area of the plating portion 95 in the binary image obtained by binarizing the master image and the area in the binary image obtained by binarizing the target image is acquired, and in the image, an area larger than the threshold value for the comparison inspection indicated by the inspection data set 411 is detected as a defect 79. In the example of FIG. 9A, a chip has occurred in the leftmost pad, and the portion surrounded by the thick solid line in FIG. 10A is detected as a defect 79. The comparison inspection may be performed by other known methods.

[0044] FIG. 10B is a diagram for explaining the foreign matter inspection. In the foreign matter inspection of the plating portion 95, for example, the gradation value of each position of the plating portion 95 in the target image of FIG. 9A is acquired for each color component. A set (area) of positions where the gradation value is outside the range of the threshold values (upper limit value and lower limit value) for the foreign matter inspection indicated by the inspection data set 411 is detected as a defect 79. In the example of FIG. 9A, a foreign matter exists on the central pad, and the portion surrounded by the thick solid line in FIG. 10B is detected as a defect 79. The foreign matter inspection may be performed by other known methods.

[0045] FIG. 10C is a diagram for explaining unevenness inspection. For example, the unevenness inspection is performed when no defect is detected in the foreign object inspection. In the unevenness inspection of the plating portion 95, for example, the color of each position of the plating portion 95 in the target image of FIG. 9A is compared with the color of the corresponding position in the master image of FIG. 9B. Then, a set (region) of positions where the color difference (for example, the sum of the squares of the differences in the gradation values of each RGB color component) is equal to or greater than the threshold value for unevenness inspection indicated by the inspection data set 411 is detected as the defect 79. In the example of FIG. 9A, unevenness exists on the rightmost pad, and the portion surrounded by the thick solid line in FIG. 10C is detected as the defect 79. The unevenness inspection may be performed by other known methods.

[0046] FIG. 11 is a diagram showing the flow of the process for inspecting the printed circuit board 9. In the inspection apparatus 1 of FIG. 1, first, the printed circuit board 9 to be inspected is placed on the stage 24. In the image acquisition unit 2, a visible light image 71 of the printed circuit board 9 is acquired using visible light, and an infrared light image 72 of the printed circuit board 9 is acquired using infrared light (step S11). The visible light image 71 and the infrared light image 72 are input to the inspection unit 41 of FIG. 3. In this processing example, immediately after the acquisition of the visible light image 71 and the infrared light image 72, the printed circuit board 9 is carried out to the carry-out position P1.

[0047] In the inspection unit 41, inspection processing is executed for each of the visible light image 71 and the infrared light image 72 (step S12). In the inspection processing, as described above, the inspection data set 411 is used, and the inspection regions of the plating portion 95, the first SR portion 96, the second SR portion 97, and the silk portion 98 are specified. Then, for each inspection region of the visible light image 71, comparison inspection, foreign object inspection, and unevenness inspection are executed, and for each inspection region of the infrared light image 72, comparison inspection, foreign object inspection, and unevenness inspection are executed. The inspection processing result of the visible light image 71 includes the results of a plurality of types of inspections for each inspection region, and the inspection processing result of the infrared light image 72 also includes the results of a plurality of types of inspections for each inspection region.

[0048] The inspection result of the visible light image 71 and the inspection result of the infrared light image 72 are input to the defect type determination unit 42. When a defect (hereinafter referred to as a "detected defect") is detected in any of the inspections (step S13), the defect type determination unit 42 determines the defect type of each detected defect (step S14). If no defect is detected (step S13), steps S14 and steps S15 and S16 described later are not performed, and the inspection of the printed circuit board 9 to be inspected is completed.

[0049] Here, the relationship between defects of various defect types and the inspection results of the visible light image 71 and the infrared light image 72 will be described. FIG. 12 is a diagram showing the visible light image 71 and the infrared light image 72 including the positions of defects of each of a plurality of defect types (hereinafter simply referred to as "defect positions"). In each row, the "defect type" column indicates the defect type of the defect, and on the right side thereof, the visible light image 71 (portion) and the infrared light image 72 (portion) including the defect position are shown side by side. In the visible light image 71, the defect position is indicated by a white arrow. In FIG. 12, the reference numerals of the visible light image 71 and the infrared light image 72 are omitted.

[0050] The "visible light inspection process" column shows the type of one inspection for the defect position (including the inspection area) of the visible light image 71 and the enlarged image of the defect position, and the "infrared light inspection process" column shows the type of one inspection for the defect position of the infrared light image 72 and the enlarged image of the defect position. The "visible light" column shows the type and result of the inspection for the defect position of the visible light image 71, and the "infrared light" column shows the type and result of the inspection for the defect position of the infrared light image 72. In the result of the inspection, "NG" means detection of a defect, and "OK" means non-detection of a defect. The "serious defect" column is the same as the "serious defect flag" in FIG. 13 described later.

[0051] In FIG. 12, in the example where the defect type is a pattern disconnection, in both the visible light image 71 and the infrared light image 72, the defect (pattern disconnection) in the first SR portion 96 can be clearly confirmed, and the results of the comparative inspections for the defect positions are both NG. In contrast, in the example of ink adhesion on the pattern, the defect is not clearly confirmed in the infrared light image 72, and the result of the comparative inspection is OK. Thus, it becomes possible to distinguish between a pattern disconnection and ink adhesion on the pattern, which appear to have the same color tone in the visible light image 71.

[0052] In the example of pad indentation, the results of the foreign object inspection of the visible light image 71 and the unevenness inspection of the infrared light image 72 for the defect position on the plating portion 95 are both NG. In contrast, in the example of SR adhesion on the pad, the result of the foreign object inspection of the visible light image 71 is NG, but the result of the unevenness inspection of the infrared light image 72 is OK. Thus, it becomes possible to distinguish between pad indentation and SR adhesion on the pad, which appear to have the same color tone in the visible light image 71.

[0053] In the example of a metal foreign object between patterns, the results of the comparative inspection of the visible light image 71 and the unevenness inspection of the infrared light image 72 for the defect position on the second SR portion 97 are both NG. In contrast, in the example of a non-metal foreign object between patterns, the result of the comparative inspection of the visible light image 71 is NG, but the result of the unevenness inspection of the infrared light image 72 is OK. Therefore, it becomes possible to distinguish between a metal foreign object between patterns and a non-metal foreign object between patterns. In the example of SR peeling, the result of the foreign object inspection of the visible light image 71 for the defect position on the first SR portion 96 is NG, but the result of the foreign object inspection of the infrared light image 72 is OK. Thus, it also becomes possible to identify SR peeling.

[0054] In the defect type determination unit 42, the defect type of the detected defect is determined by using the relationship between the defects of each defect type and the inspection processing results of the visible light image 71 and the infrared light image 72. In this processing example, a defect determination matrix 421 associating a plurality of combinations of the region type of the inspection region where a defect exists (that is, the region where the defect exists), the inspection processing result of the visible light image, and the inspection processing result of the infrared light image with a plurality of defect types is stored in advance in the defect type determination unit 42.

[0055] FIG. 13 is a diagram showing the defect determination matrix 421. In each row of the defect determination matrix 421 with each number, the column of "region type" indicates the region type of the inspection region where a defect exists, and the columns of "visible light inspection processing result" and "infrared light inspection processing result" are the same as the columns of "visible light" and "infrared light" in FIG. 12. The column of "defect type" indicates the defect type of the defect, and the column of "critical defect flag" indicates the ON / OFF of a flag indicating that the defect type is a critical defect. "○" means ON of the critical defect flag, and "-" means OFF of the critical defect flag.

[0056] For example, as shown in the line numbered 1, when the area type of the inspection area where a detection defect exists is the first SR section 96, the result of the comparison inspection of the visible light image 71 for the inspection area is NG, and the result of the comparison inspection of the infrared light image 72 for the inspection area is NG, the defect type of the detection defect is determined to be a pattern disconnection. Since the pattern disconnection is a serious defect for which the shipment of the printed circuit board 9 including the detection defect is not permitted, the serious defect flag is set to ON. Also, as shown in the line numbered 4, when the area type of the inspection area where a detection defect exists is the plating section 95, the result of the foreign matter inspection of the visible light image 71 for the inspection area is NG, and the result of the unevenness inspection of the infrared light image 72 for the inspection area is OK, the defect type of the detection defect is determined to be SR adhesion on the pattern. Since the SR adhesion on the pattern is a minor defect, the serious defect flag is set to OFF. Thus, in the determination of the defect type of the detection defect, by referring to the defect determination matrix 421 using the area type of the area where the detection defect exists, as well as the inspection processing result of the visible light image 71 for the detection defect and the inspection processing result of the infrared light image 72, the defect type of the detection defect is determined.

[0057] When the defect type of the detected defect is determined, the detected defect is displayed on the display unit 35 under the control of the display control unit 43 (step S15). FIG. 14 is a diagram showing an image (display image) displayed on the display unit 35. In the example of FIG. 14, in the identification area 81 of the display image, the number of the printed circuit board 9 to be inspected and the identification symbol on the main surface of the printed circuit board 9 imaged by the image acquisition unit 2 are displayed. In the image display area 82, the visible light image 71 and the infrared light image 72 including each detected defect are displayed side by side. In FIG. 14, one detected defect is selected, and the peripheries of the visible light image 71 and the infrared light image 72 (the upper left visible light image 71 and infrared light image 72) of the detected defect are colored differently from other detected defects. Further, for the detected defect with the serious defect flag ON, the peripheries of the visible light image 71 and the infrared light image 72 are surrounded by a thick-line rectangle F1, making it distinguishable from other detected defects. In the overall display area 83, the overall image of the printed circuit board 9 is displayed, and the position of the detected defect being selected in the image display area 82 on the printed circuit board 9 is indicated by a crosshair.

[0058] If the detected defect with the serious defect flag ON can be distinguished from other detected defects, it may be highlighted in other ways. For example, the colors of the outer edges of the visible light image 71 and the infrared light image 72 may be distinguished from those of other detected defects, or characters such as "serious defect" may be displayed. In the display image, the defect type (for example, characters such as "pattern disconnection") of each detected defect may be displayed together with the visible light image 71 and the infrared light image 72.

[0059] An operator performs a verification operation to determine whether the detected defect is a true serious defect by checking the visible light image 71 and the infrared light image 72 of each detected defect in the image display area 82 (step S16). At this time, by displaying the detected defect with the serious defect flag turned ON by the defect type determination unit 42 in a distinguishable manner from other detected defects and making the operator recognize that the detected defect is likely to be a serious defect (alerting), it is possible to reduce the oversight of serious defects. Thus, the process of inspecting the printed circuit board 9 is completed.

[0060] Actually, the above steps S11 to S16 are performed on a large number of printed circuit boards 9. The printed circuit boards 9 that do not contain true serious defects are sent to the process for shipment to customers as good products. The printed circuit boards 9 that contain true serious defects are discarded as defective products and are not shipped to customers. Thus, in this processing example, some of the plurality of defect types are specified as serious defects, and different processing is performed on the printed circuit boards 9 that contain defects that are serious defects compared to other printed circuit boards 9. Depending on the defect type or the like determined to be a serious defect, a repair operation or the like may be performed on the printed circuit board 9.

[0061] As described above, the inspection device 1 includes an image acquisition unit 2, an inspection unit 41, and a defect type determination unit 42. The image acquisition unit 2 acquires a visible light image 71 of the printed circuit board 9 using visible light and acquires an infrared light image 72 of the printed circuit board 9 using infrared light. The inspection unit 41 executes an inspection process on each of the visible light image 71 and the infrared light image 72 to detect defects on the printed circuit board 9. The defect type determination unit 42 determines the defect type of the defect based on the inspection process result of the visible light image 71 for the defect detected by the inspection unit 41, the inspection process result of the infrared light image 72, and the region type of the existence region of the defect. Thereby, the defect type of the defect can be determined in detail, and as a result, it is possible to reduce the overlooking of serious defects.

[0062] Preferably, the inspection unit 41 executes an inspection process using an inspection data set 411 indicating the position information and region type of a plurality of inspection regions on the printed circuit board 9. Thereby, the region type of the existence region of the defect can be easily acquired.

[0063] Preferably, the inspection unit 41 executes a plurality of types of inspections as inspection processes on each of the visible light image 71 and the infrared light image 72. And, the inspection result of the visible light image 71 includes the results of a plurality of types of inspections, and the inspection result of the infrared light image 72 includes the results of a plurality of types of inspections. In this way, by using the results of a plurality of types of inspections in each of the visible light image 71 and the infrared light image 72, it is possible to more precisely determine the type of defect. Depending on the design of the inspection apparatus 1, the inspection unit 41 may execute only one type of inspection on each of the visible light image 71 and the infrared light image 72.

[0064] Preferably, the defect type determination unit 42 stores a defect determination matrix 421 in which a plurality of combinations of the region type of the defect presence region, the inspection result of the visible light image, and the inspection result of the infrared light image are associated with a plurality of defect types. In this way, by using the defect determination matrix 421, it is possible to easily determine the defect type. In the inspection apparatus 1, it is possible for an operator to add other defect types to the defect determination matrix 421 based on the actual inspection results, that is, to update the defect determination matrix 421.

[0065] Preferably, the inspection apparatus 1 further includes a display control unit 43 that causes the display unit 35 to display the defects detected by the inspection unit 41. Also, in the defect type determination unit 42, some of the plurality of defect types are specified as serious defects, and the display control unit 43 causes the display unit 35 to display the defects that are serious defects in a distinguishable manner from other defects. Thereby, the operator can easily recognize the defects determined as serious defects, and the overlooking of serious defects by the operator can be reduced.

[0066] In the printed circuit board 9, a solder resist layer 913 is provided on the surface, but the inspection unit 41 can detect defects in the lower layer of the solder resist layer 913 by using the infrared light image 72. In this way, by detecting defects in the lower layer of the solder resist layer 913, it is possible to accurately determine the defect type.

[0067] The inspection method of FIG. 11 includes a step of acquiring a visible light image 71 of the printed circuit board 9 using visible light and acquiring an infrared light image 72 of the printed circuit board 9 using infrared light (step S11), a step of performing an inspection process on each of the visible light image 71 and the infrared light image 72 to detect defects of the printed circuit board 9 (step S12), and a step of determining the defect type of the defect based on the inspection result of the visible light image 71, the inspection result of the infrared light image 72, and the region type of the existence region of the defect for the defect detected in step S12 (step S14). Thereby, the defect type of the defect can be determined in detail.

[0068] In the process shown in FIG. 11, the printed circuit board 9 including the detected defect for which the heavy defect flag is set to ON by the defect type determination unit 42 may be conveyed to a carry-out position different from that of the other printed circuit boards 9 (auxiliary carry-out position P2 in FIG. 1). Specifically, the defect type of each detected defect of the printed circuit board 9 is determined by the defect type determination unit 42 (step S14). When the heavy defect flag is set to ON for at least one detected defect, the computer 3 controls the carry-out mechanism 11, whereby the printed circuit board 9 is conveyed to the auxiliary carry-out position P2. In this case, the display of the detected defect (step S15) and the verification work (step S16) on the printed circuit board 9 are omitted. When the heavy defect flags of all the detected defects on the printed circuit board 9 are OFF, steps S15 and S16 are performed in the same manner as in the above processing example. When it is determined by the verification work that any of the detected defects is a true heavy defect, the printed circuit board 9 is conveyed to the auxiliary carry-out position P2. When it is determined that all the detected defects are not true heavy defects, the printed circuit board 9 is conveyed to the carry-out position P1.

[0069] As described above, the preferred inspection apparatus 1 further includes a carry-out mechanism 11 that conveys the printed circuit board 9 after imaging by the image acquisition unit 2 to a predetermined carry-out position. In the defect type determination unit 42, some of the plurality of defect types are specified as serious defects, and the carry-out mechanism 11 conveys the printed circuit board 9 including a (highly likely) serious defect to a position different from that of other printed circuit boards. Thereby, it is possible to prevent or suppress mixing of the printed circuit board 9 including a serious defect and the printed circuit board 9 not including a serious defect. Further, by omitting the verification operation of the printed circuit board 9 including a (highly likely) serious defect, it is possible to prevent the printed circuit board 9 including a serious defect from being treated as a non-defective product due to a human error in the verification operation.

[0070] In the foreign matter inspection in the inspection unit 41, in the target images (visible light image 71 and infrared light image 72), regions outside the range of the threshold value for foreign matter inspection are detected as defects, but defects with a gradation value higher than the range and defects with a gradation value lower than the range may be distinguished as bright defects and dark defects, respectively. Similarly, in the unevenness inspection, bright defects and dark defects may be detected separately. In this case, in the defect type determination unit 42, for each of the foreign matter inspection and the unevenness inspection, bright defects and dark defects are distinguished, and the defect type of the detected defect is determined.

[0071] For example, when the region type of the inspection region where a detected defect exists is the plating portion 95, the result of the foreign matter inspection for the inspection region in the visible light image 71 is a dark defect, and the result of the unevenness inspection for the inspection region in the infrared light image 72 is OK, the defect type of the detected defect is determined to be SR adhesion on the pattern. When the region type of the inspection region where a detected defect exists is the plating portion 95, the result of the foreign matter inspection for the inspection region in the visible light image 71 is a bright defect, and the result of the unevenness inspection for the inspection region in the infrared light image 72 is OK, the defect type of the detected defect is determined to be silk ink adhesion on the pattern.

[0072] As described above, in the inspection apparatus 1, by distinguishing between bright defects and dark defects in the inspection processing results of the visible light image 71 and the inspection processing results of the infrared light image 72, it becomes possible to more accurately determine the defect type. In this processing example, bright defects and dark defects may be distinguished only in one of the inspection processing of the visible light image 71 or the inspection processing of the infrared light image 72. That is, it is only necessary to distinguish between bright defects and dark defects in the inspection processing results of the visible light image 71 and / or the inspection processing results of the infrared light image 72. Bright defects and dark defects may be distinguished only in one of the foreign matter inspection or the unevenness inspection.

[0073] Various modifications are possible in the above-described inspection apparatus 1 and inspection method.

[0074] In the inspection unit 41, the inspection process may be executed without using the inspection data set 411. In this case, the inspection unit 41 and the defect type determination unit 42 may specify the area type of the inspection area (the area type of the defect presence area), for example, by using the LUT 49 or design data.

[0075] The defect type determination unit 42 may determine the defect type of the defect without using the defect determination matrix 421. For example, the defect type determination unit 42 may have a determination device that outputs the defect type of the defect by inputting the area type of the defect presence area, the inspection processing result of the visible light image 71, and the inspection processing result of the infrared light image 72. In constructing such a determination device, a large number of teacher data with defect type labels are prepared for combinations of the area type of the defect presence area, the inspection processing result of the visible light image, and the inspection processing result of the infrared light image, and machine learning using the large number of teacher data is performed.

[0076] As described below, the object to be inspected in the inspection apparatus 1 may be a substrate other than the printed circuit board 9. However, when the object to be inspected is the printed circuit board 9, as described above, in the inspection unit 41, it is possible to detect defects in the lower layer of the solder resist layer 913 using the infrared light image 72. That is, the inspection processing result of the infrared light image 72 includes the detection result of the defects in the lower layer of the solder resist layer 913. In the inspection apparatus 1, when it is assumed that the region of the solder resist layer 913 is inspected, the defect type determination unit 42 may determine the defect type of the defect based on the inspection processing result of the visible light image 71 and the inspection processing result of the infrared light image 72 for the defect detected by the inspection unit 41 (without using the region type of the defect existence region). Also in this case, considering the presence or absence of defects in the lower layer of the solder resist layer 913, etc., the defect type of the defect can be determined in detail.

[0077] The object to be inspected in the inspection apparatus 1 may be a substrate such as a semiconductor substrate or a glass substrate in addition to the printed circuit board 9.

[0078] The configurations in the above-described embodiment and each modification may be appropriately combined as long as they do not conflict with each other.

Explanation of Reference Numerals

[0079] 1 Inspection apparatus 2 Image acquisition unit 9 Printed circuit board 11 Carry-out mechanism 35 Display unit <x 41 Inspection unit 42 Defect type determination unit 43 Display control unit 71 Visible light image 72 Infrared light image 79 Defect 411 Inspection data set 421 Defect determination matrix 913 Solder resist layer P1 Carry-out position P2 Auxiliary carry-out position S11~S16 Steps

Claims

1. An inspection apparatus for inspecting a substrate, comprising: an image acquisition unit configured to acquire a visible light image of the substrate using visible light and an infrared light image of the substrate using infrared light; an inspection unit configured to perform an inspection process on each of the visible light image and the infrared light image to detect a defect of the substrate; a defect type determination unit configured to determine a defect type of the defect based on an inspection process result of the visible light image for the defect detected by the inspection unit, an inspection process result of the infrared light image, and a region type of an existence region of the defect; and an inspection apparatus comprising the same.

2. The inspection apparatus according to claim 1, wherein the inspection unit executes the inspection process using an inspection data set indicating position information and region types of a plurality of inspection regions on the substrate.

3. The inspection apparatus according to claim 1, wherein the inspection unit performs a plurality of types of inspections as the inspection process on each of the visible light image and the infrared light image, the inspection process result of the visible light image includes results of a plurality of types of inspections, and the inspection process result of the infrared light image includes results of a plurality of types of inspections.

4. The inspection apparatus according to claim 1, wherein the inspection process result of the visible light image and / or the inspection process result of the infrared light image distinguishes between a bright defect and a dark defect.

5. The inspection apparatus according to claim 1, wherein the defect type determination unit stores a defect determination matrix in which a plurality of combinations of a region type of an existence region of a defect, an inspection process result of a visible light image, and an inspection process result of an infrared light image are associated with a plurality of defect types.

6. The inspection apparatus according to claim 1, further comprising a display control unit configured to display a defect detected by the inspection unit on a display unit, wherein in the defect type determination unit, some of the plurality of defect types are specified as serious defects, and the display control unit causes the display unit to display a defect that is a serious defect so as to be distinguishable from other defects.

7. The inspection apparatus according to claim 1, further comprising a carry-out mechanism configured to carry the substrate after imaging by the image acquisition unit to a predetermined carry-out position, wherein in the defect type determination unit, some of the plurality of defect types are specified as serious defects, and the carry-out mechanism carries a substrate including a defect that is a serious defect to a position different from that of other substrates.

8. An inspection apparatus according to any one of claims 1 to 7, wherein the substrate is a printed circuit board, and a solder resist layer is provided on the surface of the substrate, and the inspection unit is an inspection apparatus that detects defects in a lower layer of the solder resist layer using the infrared light image.

9. An inspection apparatus for inspecting a substrate, comprising an image acquisition unit that acquires a visible light image of the substrate using visible light and acquires an infrared light image of the substrate using infrared light, an inspection unit that performs an inspection process on each of the visible light image and the infrared light image to detect a defect in the substrate, and a defect type determination unit that determines a defect type of the defect based on an inspection process result of the visible light image and an inspection process result of the infrared light image for the defect detected by the inspection unit. The inspection apparatus is provided with: wherein the substrate is a printed circuit board, and a solder resist layer is provided on the surface of the substrate, and the inspection process result of the infrared light image includes a detection result of a defect in a lower layer of the solder resist layer.

10. An inspection method for inspecting a substrate, comprising: a) a step of acquiring a visible light image of the substrate using visible light and acquiring an infrared light image of the substrate using infrared light; b) a step of performing an inspection process on each of the visible light image and the infrared light image to detect a defect in the substrate; c) a step of determining a defect type of the defect based on an inspection process result of the visible light image, an inspection process result of the infrared light image, and a region type of an existence region of the defect for the defect detected in the step b). The inspection method is provided with:

11. The inspection method according to claim 10, wherein in the step c), a defect determination matrix in which a plurality of combinations of a region type of an existence region of a defect, an inspection process result of a visible light image, and an inspection process result of an infrared light image are associated with a plurality of defect types is used.

12. The inspection method according to claim 10 or 11, wherein some of a plurality of defect types are specified as serious defects, and a different process is performed on a substrate including a defect that is a serious defect from other substrates.

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