TWI590725B - Detecting device and detecting method of appearance of printed circuit board - Google Patents

Description

Inspection device and inspection method for printed circuit board appearance

The present invention relates to a technique for inspecting the appearance of a printed circuit board.

The appearance of printed circuit boards has always been checked. The printed circuit board is provided with a solder resist portion having a solder resist on its surface, and a plating portion plated with gold or copper. Since the solder resist portion and the plating portion are different in color from each other, a color image is often used when inspecting a printed circuit board.

In addition, a method is proposed in International Publication No. 2007/074770, in which a color image signal of an inspection object is obtained when a wafer is inspected, and a plurality of analysis images are obtained based on a plurality of signal components constituting the color image signal, and A defect candidate is detected for each analysis image. Japanese Laid-Open Patent Publication No. Hei 8-318619 discloses a method of multiplying a RGB value by a predetermined coefficient for a color image input from a red green blue (RGB) color camera when inspecting a printed matter. After the addition, the color image is converted into a black and white image, and the black and white image is inspected.

But sometimes in the color image obtained by shooting a printed circuit board, such as solder mask The contrast in the portion becomes low, and it is difficult to detect defects existing under the solder resist when inspecting the printed circuit board.

The present invention is suitable for an inspection apparatus for inspecting the appearance of a printed circuit board, and aims to accurately detect defects on the printed circuit board.

The inspection apparatus according to the present invention includes: a color image capturing unit that acquires an image of a plurality of color components of the printed circuit board as a color captured image; and a monochrome image capturing unit that obtains a black and white grayscale image of the printed circuit board as black and white a captured image; and a defect detecting unit that detects a defect on the first area on the printed circuit board using the color captured image, and detects a second area on the printed circuit board using the black-and-white captured image defect.

According to the present invention, it is possible to accurately detect defects on a printed circuit board.

In a preferred embodiment of the present invention, a light receiving unit is provided as the color image capturing unit and the black and white image capturing unit, and the light receiving unit is arranged with a plurality of light receiving units of the color image capturing unit. The element and the plurality of light receiving elements of the black and white image capturing unit, wherein the color captured image and the black and white captured image are simultaneously acquired on one area of the printed circuit board by the light receiving unit.

In this case, preferably, the inspection apparatus further includes: an optical system having an objective lens, an optical axis between the printed circuit board and the objective lens being perpendicular to the printed circuit board, and the optical system facing a light receiving unit guides light incident from the printed circuit board into the objective lens along the optical axis; and a slanting illumination portion from the optical axis The direction of the tilt illuminates the printed circuit board.

In another preferred embodiment of the present invention, the second region includes a solder resist. In this case, it is preferable that the defect detecting unit detects the type of the defect detected by the solder resist portion included in the second region based on the color of the defect expressed by the color imaged image. sort. More preferably, the inspection device further includes a memory portion that memorizes an error information table that indicates a range of color of the false defect as a false defect color in a color space defined by the plurality of color components In the range, the defect detecting unit classifies, in the defect detected by the solder resist portion, a portion in which the color space exists and the false defect color range overlap as a false defect.

In an embodiment of the invention, the second region includes a solder portion.

In another embodiment of the invention, the second region comprises a plating portion.

The present invention is also applicable to an inspection method for inspecting the appearance of a printed circuit board, comprising: a) a step of obtaining an image of a plurality of color components of the printed circuit board as a color image by using a color image capturing unit; b) And obtaining a black-and-white gray-scale image of the printed circuit board as a black-and-white captured image by using a black-and-white image capturing unit; and c) detecting the first region on the printed circuit board using the color captured image Defects and detecting defects in the second region on the printed circuit board using the black and white camera image.

The above object and other objects, features, embodiments and advantages will be apparent from the accompanying drawings.

1‧‧‧Checking device

2‧‧‧Device body

3‧‧‧Photographic components

5‧‧‧ computer

8‧‧‧ Recording media

9‧‧‧Printed circuit board

22‧‧‧ mounting table

23‧‧‧Station drive department

31‧‧‧Attacking Lighting Department

32‧‧‧ oblique lighting department

33‧‧‧Optical system

34‧‧‧Light receiving unit

41‧‧‧ Computing Department

42‧‧‧Form Update Department

43‧‧‧Defect Detection Department

44‧‧‧Display Control Department

49‧‧‧Memory Department

51‧‧‧Central Processing Unit

52‧‧‧Read-only memory

53‧‧‧ Random access memory

54‧‧‧Fixed Disk

55‧‧‧ display

56‧‧‧ Input Department

56a‧‧‧ keyboard

56b‧‧‧mouse

57‧‧‧Reading device

58‧‧‧Communication Department

80‧‧‧ program

91‧‧‧Resistance welding department

92‧‧‧Plating Department

93‧‧‧Wire section

94‧‧‧ solder department

321‧‧‧Light source

331‧‧‧ Objective lens

332‧‧‧half mirror

341‧‧‧Color Image Camera

342‧‧‧Black and White Image Camera Department

431‧‧‧Defective Area Designation Department

432‧‧‧Defect Category Classification Department

491‧‧‧Error Information Sheet

911‧‧‧Wiring Department

J1‧‧‧ optical axis

K‧‧‧ Defective area

L‧‧‧ line

S11~S17‧‧‧Steps

Fig. 1 is a view showing the configuration of an inspection apparatus.

Fig. 2 is a view showing the configuration of a computer.

Fig. 3 is a block diagram showing a functional configuration of an inspection apparatus.

4 is a view showing a processing flow of inspecting a printed circuit board.

5 is a view showing changes in pixel values of a pattern formed on a printed circuit board, and a color captured image and a black-and-white captured image.

Fig. 6 is a photograph showing a color captured image and a black-and-white captured image.

Fig. 7 is a photograph showing a color captured image and a black-and-white captured image.

8 is a view showing changes in pixel values of a color captured image and a black-and-white captured image.

FIG. 9 is a view showing changes in pixel values of a color captured image and a black-and-white captured image.

Fig. 10 is a view showing a color captured image.

FIG. 11 is a view showing a change in pixel values of a color captured image.

Fig. 12 is a view showing a color captured image.

FIG. 13 is a view showing a change in pixel values of a color captured image.

Fig. 14 is a photograph showing a color captured image, a black-and-white generated image, and a black-and-white captured image.

15 is a view showing changes in pixel values of a color captured image, a black-and-white generated image, and a black-and-white captured image.

Fig. 16 is a view showing spectral sensitivity characteristics of a color image capturing unit;

Fig. 17 is a view showing spectral sensitivity characteristics of a monochrome image capturing unit;

18 is a view showing changes in pixel values of a pattern formed on a printed circuit board, and a color captured image and a black-and-white captured image.

FIG. 1 is a view showing a configuration of an inspection apparatus 1 according to an embodiment of the present invention. The inspection device 1 is a device that inspects, for example, the appearance of a printed circuit board 9 (also referred to as a printed wiring substrate) before mounting an electronic component.

The inspection apparatus 1 includes an apparatus main body 2 for imaging the printed circuit board 9, and a computer 5 for controlling the overall operation of the inspection apparatus 1, and realizing the following calculation unit. The apparatus main body 2 includes an image pickup device 3 that captures an image of each inspection target area on the printed circuit board 9 to obtain a captured image (data); a stage 22 holds the printed circuit board 9; The stage driving unit 23 moves the stage 22 and the imaging element 3 relative to each other. The stage driving unit 23 is constituted by a ball screw, a guide rail, a motor, or the like.

The imaging element 3 includes a first illumination unit 31, a second illumination unit 32, an optical system 33, and a light receiving unit 34. The first illumination unit 31 and the second illumination unit 32 emit white light as illumination light. The optical system 33 has an objective lens 331, a half mirror 332, and other lenses (not shown). The illumination light emitted from the first illumination unit 31 is reflected by the half mirror 332, passes through the objective lens 331 or the like, and is then irradiated onto the printed circuit board 9. In the optical system 33, the optical axis J1 between the objective lens 331 and the printed circuit board 9 is perpendicular to The main surface of the printed circuit board 9 is illuminated by the illumination light from the first illumination portion 31 to the printed circuit board 9. The light incident on the objective lens 331 from the printed circuit board 9 along the optical axis J1 is guided to the light receiving unit 34 by the half mirror 332 or the like. As described above, the illumination light from the first illumination unit 31 is utilized for so-called epi-illumination (coaxial epi-illumination), that is, the illumination of the printed circuit board 9 after passing through the objective lens 331, and in the following description, the first illumination portion 31 is used. It is called "emission illumination unit 31".

The second illumination unit 32 has a plurality of light sources 321. The plurality of light sources 321 are fixed to the lens barrel of the optical system 33 and disposed on the side of the lens barrel. The plurality of light sources 321 illuminate the printed circuit board 9 from a direction oblique to the optical axis J1 between the objective lens 331 and the printed circuit board 9. That is, the illumination light from the second illumination unit 32 is used for so-called oblique illumination, that is, light is irradiated from a direction oblique to the optical axis J1, and in the following description, the second illumination portion 32 is referred to as "the oblique illumination portion 32. ". The irradiation area of the illumination light from the oblique illumination unit 32 on the printed circuit board 9 includes an irradiation area of the illumination light from the epi-illumination part 31 on the printed circuit board 9, and an imaging area by the light receiving unit 34. In the present processing example, the intensity of the illumination light from the epi-illumination unit 31 is substantially the same as the intensity of the illumination light from the oblique illumination unit 32.

The light receiving unit 34 converts an image of the printed circuit board 9 imaged on the light receiving surface by the optical system 33 into an electric signal. In detail, the light receiving unit 34 includes a plurality of light receiving elements provided with an R (red) filter, a plurality of light receiving elements provided with a G (green) filter, and a B (blue) filter. a plurality of light receiving elements and a plurality of light receiving elements not provided with a color filter. The light receiving element is, for example, a charge coupled device (CCD). On the light receiving surface of the light receiving unit 34, this Some light-receiving elements are mixed and arranged two-dimensionally, and an R image using an R filter, a G image using a G filter, a B image using a B filter, and an unused color are obtained. The image of the filter.

The image in which the color filter is not used is a black-and-white gray-scale image indicating the brightness at each position of the imaging region on the printed circuit board 9. In the following description, an image in which a color filter is not used is referred to as a "black and white image", and a set of a plurality of light receiving elements that obtain a black and white image is referred to as a "black and white image capturing unit". Further, an image set of R, G, and B, that is, an image in which each pixel has a value (pixel value) of R, G, and B is referred to as a "color captured image", and a plurality of color captured images are obtained. The set of light receiving elements is referred to as a "color image capturing unit". In the light receiving unit 34, a color captured image and a black and white captured image are simultaneously acquired for the same region (imaging region) on the printed circuit board 9.

FIG. 2 is a view showing the configuration of the computer 5. The computer 5 is a common computer system, and includes a central processing unit (CPU) 51 for performing various arithmetic processing, a read-only memory (ROM) 52, a memory basic program, and a random memory. Take memory (random access memory, RAM) 53, and remember various information. The computer 5 further includes: a fixed disk 54 for storing information; a display 55 for displaying various information such as an image; and a keyboard 56a and a mouse 56b for accepting input from an operator (hereinafter collectively referred to as "input portion 56") The reading device 57 reads information from a computer-readable recording medium 8 such as an optical disk, a magnetic disk, or a magneto-optical disk; and the communication unit 58 transmits and receives signals to and from other configurations of the inspection device 1.

In the computer 5, the reading process is read from the recording medium 8 via the reading device 57 in advance. Equation 80, and the program 80 is memorized to the fixed disk 54. The CPU 51 executes arithmetic processing while using the RAM 53 or the fixed disk 54 in accordance with the program 80.

3 is a block diagram showing a functional configuration of the inspection apparatus 1. In FIG. 3, a functional configuration realized by the CPU 51, the ROM 52, the RAM 53, the fixed disk 54, and the like of the computer 5 is surrounded by a dotted rectangle of the reference numeral 5. The computer 5 has a calculation unit 41, a storage unit 49, an input unit 56, and a display 55. The calculation unit 41 includes a table update unit 42, a defect detection unit 43, and a display control unit 44. The defect detection unit 43 includes a defect area designation unit 431 and a defect type classification unit 432. Details of the functions realized by these configurations will be described below. Moreover, these functions can be constructed by dedicated circuits, or dedicated circuits can be partially utilized.

FIG. 4 is a view showing a processing flow of the inspection apparatus 1 inspecting the printed circuit board 9. In Fig. 4, step S17 indicated by a broken line rectangle is performed in another processing example described below, and the table updating portion 42 in Fig. 3 is used for the other processing example.

In the inspection apparatus 1 of FIG. 1, the printed circuit board 9 to be inspected is placed on the mounting table 22, and the predetermined inspection target area on the printed circuit board 9 is placed on the light receiving unit 34 by the mounting table driving unit 23. The camera area. Then, the color image capturing unit 341 of the light receiving unit 34 of FIG. 3 acquires the color image, and the black and white image capturing unit 342 acquires the black and white image (steps S11 and S12). As described above, the color captured image and the black-and-white captured image are simultaneously acquired, and the color captured image and the black-and-white captured image are output to the defect detecting unit 43 of the computing unit 41.

FIG. 5 shows a pattern formed on the printed circuit board 9, and a color image. A graph of changes in pixel values of images and black and white captured images. The upper part of Fig. 5 shows a part of the pattern formed on the printed circuit board 9, and the middle part of Fig. 5 shows the change of the pixel value of one color component of the color imaged image on the line L in the upper stage, and the lower part of Fig. 5 shows the upper part of Fig. 5 The change in the pixel value of the black and white captured image on line L. In the middle and lower sections of FIG. 5, the vertical axis represents the pixel value, and the horizontal axis represents the position on the line L (the same in FIGS. 8, 9, 11, 13, 15, and 18 to be described later). Here, the color captured image and the black and white captured image are represented by 256 gradations of 0 to 255, respectively. Of course, the gray scale range of the color image and the black and white image is not limited to 0 to 255.

In the printed circuit board 9 of the present embodiment, as shown in the upper part of FIG. 5, the wiring portion 911 which is a circuit pattern formed of copper or the like is provided on the main surface, and the wiring portion 911 is covered with the solder resist. That is, on the main surface of the printed circuit board 9, a region 91 in which a solder resist is present on the surface (a region in which a parallel oblique line is narrowed in the upper portion of FIG. 5, hereinafter referred to as "resistance portion 91") includes wiring. Department 911. On the main surface of the printed circuit board 9, a region 92 formed by gold plating or copper plating or the like which is not covered with a solder resist (hereinafter referred to as "plating portion 92"), and screen printing on the surface of the solder resist are further provided. A region such as a character formed by (silk screen printing) or the like (hereinafter referred to as "screen portion 93"). Such a printed circuit board 9 is also referred to as a plated substrate. Regarding the reflection of light on the surface of the printed circuit board 9, the ratio of diffuse reflection and specular reflection on the plating portion 92 is the same, and the ratio of diffuse reflection on the solder resist portion 91 and the screen portion 93 is high. In the following description, the areas of the solder resist 91, the plating portion 92, and the screen portion 93 on the printed circuit board 9 are respectively shown in the black-and-white captured image and the color captured image. The field is also referred to as "soldering portion 91", "plating portion 92", and "wire portion 93".

The defect area specifying unit 431 of the defect detecting unit 43 detects a defect in the inspection target region on the printed circuit board 9 using the black-and-white captured image and the color captured image (step S13). Here, as described above, in the color image capturing unit 341, the color receiving element is provided with the color filter. In contrast, in the monochrome image capturing unit 342, the color filter is not provided with the color filter. Therefore, the sensitivity (the output value obtained when light of a predetermined intensity is incident per unit time) on each light receiving element of the monochrome image capturing unit 342 is higher than the sensitivity of each light receiving element of the color image capturing unit 341. In the light receiving unit 34, the color image capturing unit 341 and the monochrome image capturing unit 342 perform imaging under the same illumination conditions. Therefore, as shown in the middle and lower sections of FIG. 5, the blackout image is displayed for the solder resist 91. The contrast in the middle (here, the difference between the value of the brightest portion and the pixel of the darkest portion) becomes higher than the contrast in the color captured image. Therefore, as shown by the dotted circle marked with the symbol K in the upper stage of FIG. 5, when the main surface of the printed circuit board 9 is under the solder resist (between the substrate main body and the solder resist), there is a defect, and the color image In contrast, a defective area indicating the defect in a black-and-white captured image is more easily specified.

6 and 7 are photographs showing an example of a color captured image and a black-and-white captured image, and the upper part of FIGS. 6 and 7 shows a color captured image (in which a gray scale image is expressed), and the lower part shows a black and white image. image. In FIGS. 6 and 7, a symbol K is indicated in a defect region indicating a defect existing under the solder resist. 8 and 9 are diagrams showing changes in pixel values of a color captured image and a black-and-white captured image. The upper part of FIGS. 8 and 9 shows the defect area K in the upper stage of FIGS. 6 and 7. The change in the pixel value of the color captured image on the line L of the cross section, the lower part of FIGS. 8 and 9 shows the black and white image on the line L which is the cross section of the defect area K in the lower stage of FIGS. 6 and 7. The change in pixel value. In the upper stages of FIGS. 8 and 9, the lines indicating the changes in the values of R, G, and B are denoted by the symbols R, G, and B, respectively (the same in the upper stages of FIGS. 11, 13, and 15 below). It is judged from FIGS. 6 to 9 that in the black-and-white captured image, the difference between the pixel value (or luminance) of the defective region K and the other region of the background, that is, the solder resist portion 91 is larger than the difference in the color captured image.

Therefore, in the defective area specifying portion 431, the defect is detected on the solder resist portion 91 on the printed circuit board 9 using the black-and-white captured image. For example, the black-and-grey gray-scale image of the printed circuit board 9 in which no defect is present, that is, the solder resist portion 91 of the reference image, and the solder resist portion 91 of the black-and-white captured image obtained in step S12 are compared. Thereby, the defective region of the solder resist portion 91 in the black-and-white captured image is specified, and the defect of the solder resist portion 91 on the printed circuit board 9 is detected. One defective area is, for example, a set of defective pixel groups that are close to each other within a predetermined distance, by using a pixel group in which pixels representing defects are consecutive. As described below, in the present embodiment, since the defect detected by the defective area specifying unit 431 is classified into a true defect or a false defect, the defect can be understood as a defect candidate.

On the other hand, as for the plating portion 92, as shown in FIG. 5, the value of the pixel in the black-and-white captured image is the maximum pixel value (255) (that is, saturated), whereas in the color captured image The value of the pixel in is lower than the maximum pixel value. Further, in the screen portion 93, in both of the color captured image and the black-and-white captured image, the value of the pixel is the maximum pixel value. Therefore, when the material having the wire mesh portion 93 is attached to the plating portion 92 In the case of a defect on the surface, a defective area indicating the defect can be specified in the color captured image. Of course, it is also possible to specify a defective area such as a missing portion of the screen portion 93. Therefore, in the defective area specifying unit 431, the defects are detected on the plating portion 92 and the screen portion 93 on the printed circuit board 9 using the color image pickup image. For example, the plating portion 92 and the screen portion 93 of the color reference image of the printed circuit board 9 in which the defect is not present are compared with the plating portion 92 and the screen portion 93 of the color image captured in step S11. Thereby, the defective portions of the plating portion 92 and the screen portion 93 in the color imaged image are designated, and the defects of the plating portion 92 and the screen portion 93 on the printed circuit board 9 are detected.

When the defect is detected by the defect area specifying unit 431, the defect type classifying unit 432 classifies the type of each defect (step S14). Here, the type of the defect detected on the solder resist portion 91 is classified based on the color of the defect (the color of the defect region) indicated by the color imaged image. In the following description, the type of the defect is a false defect or a true defect, but the kind of the defect may be subdivided into a plurality of types of true defects and the like.

FIG. 10 is a view showing a color captured image, and FIG. 11 is a view showing a change in pixel value on a line L in which the defect region K of the solder resist portion 91 in the color captured image of FIG. 10 is cross-sectional. The defect area K of FIG. 10 indicates a minute dirt on the solder resist of the printed circuit board 9, that is, a defect (it can be understood as a poor appearance which does not affect the function of the printed circuit board 9), as shown in FIG. Among all the color components of G and B, the value of the pixel of the defective area K becomes higher than the background (lightening).

12 is a view showing a color captured image, and FIG. 13 is a view showing a pixel value on a line L in which the defect region K of the solder resist portion 91 in the color captured image of FIG. 12 is cross-sectional. The picture of the change. The defect region K of FIG. 12 indicates an oxidized portion of copper existing under the solder resist, that is, a defect (which can be understood as a malfunction), as shown in FIG. 13, the value of G of the pixel in the defective region K (the pixel value of G) Become below the background.

Therefore, in the defect type classification unit 432, the pixel value of G of each defect region K of the solder resist 91 in the color captured image is compared with the pixel value of G of the corresponding region in the color reference image. . Next, when the pixel value of G of the color imaged image is higher than the pixel value of G of the reference image, the defect area K (defect on the printed circuit board 9 indicated) is classified as a false defect, when the color image is captured When the pixel value of G is less than or equal to the pixel value of G of the reference image, the defect area K is classified into a true defect. In the defect type classification unit 432, each defect (including the defects in the plating portion 92 and the screen portion 93) on the printed circuit board 9 may be classified as a false defect or a true defect based on the size of the defect or the like.

When the defect is classified into a false defect or a true defect in the above-described manner, the display control unit 44 displays an image of the defect classified as a true defect among the defects detected by the defective area specifying unit 431 on the display 55 (step S15). ). For example, a portion of the color captured image including the rectangular region of the defect (hereinafter referred to as "color defect image") is displayed on the display 55. In the display 55, an area including the defect in the black-and-white captured image may be displayed together with the color defect image.

The operator determines the final type of defect (here, the type of the false defect or the true defect) indicated by the color defect image by referring to each color defect image, and inputs the final type to the arithmetic unit 41 via the input unit 56. (Step S16). Thereby, the inspection of the inspection target area on the printed circuit board 9 is completed. In fact, for printing electricity The plurality of inspection target areas on the road board 9 are locally subjected to the processing of the steps S11 to S16 at the same time.

As described above, the inspection apparatus 1 is provided with a color image capturing unit 341 that acquires a color captured image and a monochrome image capturing unit 342 that acquires a black-and-white captured image. Next, the defect detecting unit 43 detects a defect on the plating portion 92 and the screen portion 93 on the printed circuit board 9 using the color image, and uses the black-and-white image to the solder resist portion 91 on the printed circuit board 9. Detect defects. Thereby, defects can be accurately detected in the solder resist portion 91, the plating portion 92, and the screen portion 93 on the printed circuit board 9, respectively.

However, it is also considered to detect a defect in the solder resist 91 using a black and white image (hereinafter referred to as "black and white image") generated from a color image. FIG. 14 is a photograph showing an example of a color captured image, a black-and-white generated image, and a black-and-white captured image. The upper part of Fig. 14 shows a color captured image (in which gradation is expressed), the middle portion indicates a black-and-white image, and the lower portion indicates a black-and-white image. The value of each pixel in the black-and-white generated image is guided by the values of R, G, and B of the corresponding pixels in the color captured image. 15 is a view showing changes in pixel values of a color captured image, a black-and-white generated image, and a black-and-white captured image. The upper, middle, and lower sections of Fig. 15 respectively show changes in pixel values on the line L in which the defect regions K in the upper, middle, and lower stages of Fig. 14 are cross-sectional. As can be seen from FIG. 14 and FIG. 15, even if a black-and-white generated image is generated from the color captured image, it is difficult to increase the difference in luminance between the defective region K and the background as in the black-and-white captured image. Therefore, by detecting a defect using the black-and-white captured image in the solder resist portion 91, the defect can be detected accurately and easily as compared with the case where the image is generated using black and white.

In the defect detecting unit 43, the type of the defect detected on the solder resist 91 is classified based on the color of the defect indicated by the color captured image. Thereby, the types of defects can be classified with high precision. Further, in the process of step S15, by displaying only the image of the defect classified as the true defect on the display 55, the falseness can be reduced, and the work efficiency of the confirmation work by the worker can be improved. Further, when the number of defects detected by the defective area specifying unit 431 is small, etc., in the process of step S15, a color defect image classified as a defective defect may be displayed on the display 55. At this time, it is preferable to display the color defect image together with the classification result, and in the process of step S16, the operator determines the final type of each defect.

In the inspection apparatus 1, a light receiving unit 34 is provided as a color image capturing unit 341 and a monochrome image capturing unit 342, and the plurality of light receiving units 34 are arranged with a plurality of light receiving elements of the color image capturing unit 341 and black and white images. The plurality of light receiving elements of the imaging unit 342 and the light receiving unit 34 simultaneously acquire a color captured image and a black and white captured image on one area on the printed circuit board 9. Thereby, compared with the case where the color image imaging unit 341 and the monochrome image capturing unit 342 are separately provided, the color captured image and the black-and-white captured image can be obtained in a short time.

In the defect type classification unit 432, the defect in the solder resist 91 may be classified into a dummy defect or a true defect by a method different from the above method (or addition of the method). At this time, an error information table 491 (see FIG. 3) is prepared in advance, and the error information table 491 indicates the range of the color of the false defect as the false defect color range in the color space defined by R, G, and B, and uses the memory. The part 49 performs the memory. In the defect type classification unit 432, each position of each defective area in the color captured image is obtained. The values of R, G, and B of the pixel. Next, when the position specified by the values of R, G, and B in the color space is included in the false defect color range, the position of the defective area (the defective portion on the printed circuit board 9 indicated) is classified as a false defect. When the designated position in the color space is not included in the false defect color range, the position of the defective area is classified as a true defect (FIG. 4: step S14). In this way, among the defects detected in the solder resist 91, the portion overlapping in the color space and the false defect color range indicated by the error information table 491 are classified as false defects.

Next, a color defect image indicating a defect including a portion classified as a true defect is displayed on the display 55 (step S15). Further, the operator determines the final type of the defect indicated by each color defect image (step S16). Further, when the final type of the defect indicated by one color defect image is a false defect, the operator updates the color of all the positions of the defective area in the color defect image by the table updating unit 42 by performing predetermined input. The existence range of these colors in the color space is added (registered) as a false defect color range to the error information table 491. That is, the error information table 491 is updated (step S17). The additional false defect color range can be easily performed by, for example, moving the mouse pointer a plurality of times on the color defect image on the display 55, and selecting "register the false defect color range by right clicking on the mouse to display the menu. ". The updated error information table 491 is utilized for the defect classification in the processing of the next step S14.

As described above, in the inspection apparatus 1, an error information table 491 is prepared in advance, which indicates a range of color of a false defect as a false defect color range in a color space defined by a plurality of color components, and will block Detected on the welded portion 91 Among the defects, a portion in which the range of existence in the color space overlaps with the color range of the false defect is classified as a false defect. Thereby, it is possible to easily distinguish false defects.

Further, when the printed circuit board 9 is inspected, there is a case where it is required to strictly check for defects in the plating portion 92. In this case, the inspection device 1 sets the intensity of the illumination light from the epi-illumination unit 31 of FIG. 1 to a value lower than the intensity of the illumination light from the oblique illumination unit 32. Further, the gain in the monochrome image capturing unit 342 is also lowered. Therefore, in the black-and-white captured image acquired by the monochrome image capturing unit 342, the value of the pixel in the plating portion 92 is much lower than the maximum pixel value (255).

FIG. 16 is a view showing spectral sensitivity characteristics of the color image capturing unit 341, and FIG. 17 is a view showing spectral sensitivity characteristics of the monochrome image capturing unit 342. 16 and 17, the vertical axis represents the relative sensitivity, and the horizontal axis represents the wavelength of the incident light. The relative sensitivity is the value obtained by dividing the sensitivity of each wavelength of incident light by the maximum sensitivity. In FIG. 16, the lines of the spectral sensitivity characteristics of the light receiving element of R, the light receiving element of G, and the light receiving element of B are denoted by symbols R, G, and B, respectively. In the monochrome image capturing unit 342, as shown in FIG. 17, the relative sensitivity is relatively high in the entire wavelength range of visible light of 400 to 700 nm. On the other hand, as shown in FIG. 16 , the peaks of the relative sensitivities of the light receiving elements of R, the light receiving elements of G, and the light receiving elements of B in the color image capturing unit 341 are in the vicinity of a wavelength of 650 nm and a wavelength of 550 nm, respectively. The relative sensitivity of the color image capturing unit 341 is lower than the relative sensitivity of the monochrome image capturing unit 342 at a wavelength of around 450 nm and at a wavelength of around 500 nm and around 600 nm.

In the defect detecting unit 43, the plating portion 92 is inspected using a black-and-white captured image. Measure defects. Thereby, in the plating unit 92, it is possible to accurately detect a defect of a color of a wavelength that is difficult to detect in the color captured image. The solder mask 91 and the screen portion 93 are detected for defects using a color image.

Next, an inspection of the printed circuit board 9 in which the solder portion is formed instead of the plating portion 92 will be described. FIG. 18 is a view showing changes in pixel values of a pattern formed on the printed circuit board 9, and a color captured image and a black-and-white captured image. The upper part of Fig. 18 shows a part of the pattern formed on the printed circuit board 9, and the middle part of Fig. 18 shows the change of the pixel value of one color component of the color imaged image on the line L in the upper stage, and the lower part of Fig. 18 shows the upper part of Fig. 18 The change in the pixel value of the black and white captured image on line L.

On the printed circuit board 9 shown in the upper stage of Fig. 18, a solder resist portion 91, a solder portion 94, and a screen portion 93 are formed. The solder portion 94 is a region where the main surface of the printed circuit board 9 is formed of solder and is not covered by the solder resist. The solder resist portion 91 and the screen portion 93 are the same as the upper portion of Fig. 5 . Such a printed circuit board 9 is also referred to as a solder substrate. Regarding the light reflection on the surface of the printed circuit board 9, the ratio of diffuse reflection on the solder resist portion 91 and the screen portion 93 is high, and the ratio of specular reflection on the solder portion 94 is high.

When the printed circuit board 9 having the solder portion 94 is inspected, the intensity of the illumination light from the epi-illumination portion 31 is set to a value lower than the intensity of the illumination light from the oblique illumination portion 32. Further, the gain in the monochrome image capturing unit 342 also decreases. By imaging the printed circuit board 9 under such conditions, the color image capturing unit 341 acquires a color captured image indicating a change in the pixel value in the middle of FIG. 18, and in the monochrome image capturing unit 342, A black-and-white captured image indicating a change in the pixel value of the lower stage of FIG. 18 is acquired.

In the color captured image shown in the middle of FIG. 18, the values of the pixels of both the solder portion 94 and the screen portion 93 are the maximum pixel values, and in the black-and-white captured image shown in the lower portion of FIG. 18, the solder portion is formed. A value of the pixel of 94 is lower than the maximum pixel value, and a difference is generated between the value of the pixel of the screen portion 93. Therefore, in the defect detecting unit 43, by detecting defects on the solder portion 94 and the screen portion 93 by using the black-and-white captured image, it is possible to accurately detect, for example, a defect in which the material of the screen portion 93 adheres to the surface of the solder portion 94. . Further, the defect is detected by the solder resist portion 91 using the color image pickup image.

The inspection device 1 can be variously modified.

On the printed circuit board 9, an area in which a defect is detected using a color imaged image and a region in which a defect is detected using a black and white image can be appropriately changed. In the inspection apparatus 1, the defect is detected on the first region on the printed circuit board 9 by using the color captured image, and the defect is detected in the second region different from the first region using the black-and-white captured image, and can be accurately detected. Defects in various areas on the printed circuit board 9.

According to the design of the inspection apparatus 1, the color image capturing unit 341 and the monochrome image capturing unit 342 can be provided separately. In this case, the color captured image and the black-and-white captured image can be obtained at different timings. Further, in the color image capturing unit, a light receiving element having a filter of cyan (C), magenta (M), and yellow (yellow) color components can be used.

Depending on the type of the region in which the defect is detected in the printed circuit board 9, for example, the epi-illumination unit 31 can be turned off, and the color captured image and the black-and-white captured image can be obtained using only the illumination light from the oblique illumination unit.

The configurations in the above-described embodiments and the modifications are not contradictory to each other. It can be combined as appropriate.

Although the invention has been described and illustrated in detail, the description is illustrative and not restrictive. Therefore, various modifications or embodiments may be made without departing from the scope of the invention.

91‧‧‧Resistance welding department

92‧‧‧Plating Department

93‧‧‧Wire section

911‧‧‧Wiring Department

K‧‧‧ Defective area

L‧‧‧ line

Claims (16)

An inspection apparatus for inspecting an appearance of a printed circuit board, comprising: a color image capturing unit that acquires an image of a plurality of color components of a printed circuit board to be inspected as a color captured image; and a monochrome image capturing unit Obtaining a black-and-white grayscale image of the printed circuit board to be inspected as a black-and-white captured image; and a defect detecting unit that detects a defect on the first region of the printed circuit board of the inspection target using the color captured image Defects are detected on the printed circuit board of the inspection object on a second area different from the first area using the black and white image. The inspection apparatus according to claim 1, wherein a light receiving unit is provided as the color image capturing unit and the black and white image capturing unit, and the light receiving unit is arranged with a plurality of the color image capturing units. a light receiving element and a plurality of light receiving elements of the black and white image capturing unit, and the color receiving unit and the black and white image are simultaneously acquired on one area of the printed circuit board to be inspected by the light receiving unit image. The inspection apparatus according to claim 2, further comprising: an optical system having an objective lens, an optical axis between the printed circuit board of the inspection object and the objective lens being perpendicular to the printed circuit board of the inspection object, and The optical system directs the printed circuit from the inspection object along the optical axis toward the light receiving unit The plate enters the light of the objective lens; and the oblique illumination unit illuminates the printed circuit board of the inspection object from a direction oblique to the optical axis. The inspection apparatus according to any one of claims 1 to 3, wherein the second region comprises a solder resist. The inspection apparatus according to any one of claims 1 to 3, wherein the second region includes a solder portion. The inspection apparatus according to any one of claims 1 to 3, wherein the second region comprises a plating portion. An inspection apparatus for inspecting an appearance of a printed circuit board, comprising: a color image capturing unit that acquires an image of a plurality of color components of the printed circuit board as a color captured image; and a monochrome image capturing unit; Obtaining a black-and-white gray-scale image of the printed circuit board as a black-and-white captured image; and a defect detecting unit that detects a defect on the first area on the printed circuit board using the color captured image, and uses the black-and-white image An image detects a defect on a second area on the printed circuit board, wherein the second area includes a solder mask, wherein the defect detecting portion is based on a color of the defect represented by the color imaged image The types of defects detected by the solder resist portion included in the second region are classified. The inspection apparatus according to claim 7, further comprising a memory unit, a memory error information table, wherein the error information table indicates a range of color of the false defect in a color space defined by the plurality of color components A false defect color range, and the defect detecting portion classifies, in the defect detected by the solder resist portion, a portion in which the color space exists in a range overlapping with the false defect color range as a false defect. An inspection method for inspecting an appearance of a printed circuit board, comprising: a) a step of obtaining an image of a plurality of color components of the printed circuit board as a color image by using a color image capturing unit; a step of obtaining a black-and-white gray-scale image of the printed circuit board as a black-and-white captured image by using a black-and-white image capturing unit; and c) using the color captured image for the first on the printed circuit board The area detects a defect and detects a defect on the second area on the printed circuit board using the black and white image. The inspection method according to claim 9, wherein a light receiving unit is provided as the color image capturing unit and the black and white image capturing unit, and the light receiving unit is arranged with a plurality of the color image capturing units. The light-receiving element and the plurality of light-receiving elements of the black-and-white image capturing unit simultaneously acquire the color captured image and the black-and-white captured image on one area of the printed circuit board by the light receiving unit. The inspection method described in claim 10, wherein Directing, by the optical system, light entering the objective lens from the printed circuit board along the optical axis toward the light receiving unit, the optical system having an objective lens, and between the printed circuit board and the objective lens The optical axis is perpendicular to the printed circuit board, and in the steps a) and b), the printed circuit board is illuminated from a direction oblique to the optical axis by a slanted illumination. The inspection method according to any one of claims 9 to 11, wherein the second region comprises a solder resist. The inspection method of claim 12, further comprising the step d), based on the color of the defect represented by the color image, for the portion included in the second region in the step c) The types of defects detected by the solder mask are classified. The inspection method according to claim 13, wherein an error information table is prepared in advance, wherein the error information table indicates a range of color of the false defect as a false defect color range in a color space defined by the plurality of color components And in the step d), among the defects detected by the solder resist portion, a portion where the existence range of the color space overlaps with the false defect color range is classified as a false defect. The inspection method according to any one of claims 9 to 11, wherein the second region contains a solder portion. The inspection method according to any one of claims 9 to 11, wherein the second region comprises a plating portion.