JP4389982B2 - Substrate visual inspection device - Google Patents

Description

  According to the present invention, a printed circuit board (hereinafter referred to as “component mounting board” or simply “board”) on which a component is mounted and soldering to each mounting component is imaged and the component is mounted using the generated image. The present invention relates to a substrate visual inspection apparatus that determines suitability of a state and a solder surface state.

  The applicant has previously developed a number of substrate appearance inspection apparatuses called “color highlight methods”. This color highlight type substrate visual inspection apparatus (hereinafter simply referred to as “inspection apparatus”) includes a two-dimensional color camera and an illumination apparatus that irradiates three types of color light of red, green, and blue from different directions. (See Patent Documents 1 and 2).

Japanese Patent Publication No.6-1173 JP 2002-296198 A

  In the inspection apparatus described above, the color camera is disposed above the substrate with the light receiving surface facing the substrate surface, and the illumination device includes ring-shaped light sources that emit red, green, and blue color lights, each having a central axis. It is deployed according to the optical axis of the imaging device. In addition, the diameter and height of each light source is such that red light is emitted from the direction with the largest elevation angle with respect to the substrate surface, then green light is emitted from the direction with the largest elevation angle, and blue light is emitted from the direction with the smallest elevation angle. Has been adjusted. Moreover, it may replace with a ring-shaped light source and the illuminating device of the structure which arranged many LED concentrically may be used.

  When the solder fillet (hereinafter simply referred to as “fillet”) formed on the substrate after soldering is illuminated by the optical system having the above-described configuration, the color light from each light source is specularly reflected on the surface of the fillet, Reflected light of different colors is incident on the camera depending on the inclination angle of the fillet. Specifically, in the part where the slope of the lower part of the fillet is gentle, the reflected light from the red light source having the largest elevation angle enters the camera, and in the part where the slope of the upper part of the fillet is steep, the blue color with the smallest elevation angle. Reflected light with respect to the light from the light source enters the camera. Further, in the center of the fillet, the reflected light with respect to the light from the green light source enters the camera.

  In the color highlight inspection apparatus, the color image generated by the above optical system is binarized, and an area where each color of red, green, and blue appears (hereinafter referred to as “color area”) is extracted. Then, the area and position of each color region are measured. By comparing these measured values with reference values registered in advance, the size of the fillet and the suitability of the inclined state are determined.

Furthermore, in this inspection apparatus, the diffuse reflection is increased like the surface of the substrate or the component main body by adjusting the amount of each light so that it becomes white light when the red, green and blue color lights are mixed. The part is imaged under illumination with white light accompanying reflection. In this way, for the parts other than the solder, a color image in which the original color and shape clearly appear is generated. For example, the color of the part can be extracted for the presence / absence inspection of the part, or for the mounting error inspection. Processing such as extracting characters printed on the component body can be easily performed. Further, when displaying an image used for inspection, an image close to the actual substrate can be displayed, so that the user does not feel uncomfortable when confirming the display image.
Therefore, according to the color highlight type inspection apparatus, it is possible to execute the inspection for the solder and the inspection for the part other than the solder using the same color image.

  Further, in Patent Document 2 described above, a compensation illumination unit is provided in addition to the illumination device for color highlight illumination, and the substrate is irradiated with blue light from an angle lower than that of the color highlight illumination. Therefore, the steep surface on the side of the solder is also included in the blue region, or the combined light of each color light of the color highlight illumination and the blue light from the compensation illumination unit becomes white light. Describes that the amount of each light is adjusted.

  In the color highlight optical system, since the range of the irradiation angle of each color light is limited, the angle range of the inclined surface that can be reflected in the color image is naturally limited. For this reason, as shown in FIG. 9, when the reflection state with respect to the hemispherical solder 70 is considered, regular reflection light is incident on the camera 1 even with blue light for detecting the steep surface on the extremely steep surface at the bottom. It will be in a state that can not be made. On the flat surface of the zenith, even the red light for detecting the gentle surface cannot enter the regular reflected light into the camera 1. As described above, since any part where the specularly reflected light cannot be incident on the camera 1 is a dark region in the color image, it is difficult to specify whether the inclined state is steep or flat.

As a method for solving such a problem, a method of enlarging the illumination device so that light is irradiated from as large a range as possible, or a method of lowering the arrangement position of the illumination device can be considered.
However, since the color highlight type illumination device performs omnidirectional illumination, the width must be enlarged in all directions in order to widen the irradiation range, the illumination device becomes larger, and the board and components are larger. It cannot cope with the current downsizing. Also, if the illumination unit is lowered, it becomes difficult to accommodate a substrate on which tall components are mounted.

  In view of the above points, the present invention makes it possible to discriminate steep and flat surfaces of solder that are difficult to detect with color highlight illumination, and can image portions other than solder under white illumination as in the past. The challenge is to do so. Although the same subject is disclosed also in patent document 2, the structure for solving the problem in this invention is completely different from patent document 2.

An inspection apparatus for solving the above-described problems is arranged in a color different from the first imaging means that is disposed above the substrate to be inspected so that the light receiving surface faces the substrate surface and generates a color image of the substrate. , a plurality of visible light in the mixing becomes white light relations, different elevation for each substrate surface, and a first illumination irradiated from a direction oblique to the optical axis of the first imaging means to the substrate surface Means, a second illuminating means for irradiating the substrate surface with invisible light from the direction along the optical axis of the first imaging means , and the first imaging means with the optical axis and the field of view being aligned, A second imaging unit that receives reflected light from the substrate surface with respect to the invisible light emitted from the second illuminating unit and generates a gray image reflecting the incident state of the reflected light ; and the first imaging unit. By the generated color image and the second imaging means Performs testing of the solder on the substrate by using the generated grayscale image, the portion other than the solder, and a test execution means for executing the inspection using the image of the corresponding portion of the color image. In addition, in the inspection for the solder, the inspection execution unit is configured to detect a portion of the color image corresponding to the solder in the gray image and a portion represented by the color corresponding to the illumination light from the first illumination unit in the color image. On the other hand , the inclination angle is determined based on the irradiation direction of the illumination light corresponding to the appearing color . On the other hand, a portion that is a dark region in the color image and is represented by a lightness that exceeds the first threshold value in the grayscale image is determined from the range of the inclination angle determined by the color of the illumination light from the first illumination means. Is also determined to be a gradual surface. Further, a portion that is a dark region in the color image and is represented by a lightness that is lower than the second threshold value that is lower than the first threshold value in the gray image corresponds to the illumination light from the first illumination means. It is determined that the surface is steeper than the range of the inclination angle determined by the color .

  In the above, the first imaging unit and the first illumination unit correspond to a color highlight optical system. The first imaging unit is preferably arranged with the optical axis aligned with the vertical direction, but is not limited thereto, and may be arranged with the optical axis slightly inclined with respect to the vertical direction.

Invisible light such as infrared light and ultraviolet light is emitted from the second illumination means. Since this invisible light is irradiated from the direction along the optical axis of the first image pickup unit to the substrate surface, out of the regular reflection light for the illumination light, the optical axis of the first and second image pickup units. Proceeding along the direction is specularly reflected light from a nearly flat surface, that is, specularly reflected light from a surface on which it is difficult to make regular reflected light for visible light incident on the first imaging means. In the grayscale image generated by the regular reflected light being incident on the second imaging means, the flat surface of the solder appears as a region with higher brightness than the other portions. On the other hand, with respect to the steep surface of the solder, specularly reflected light with respect to non-visible light does not become light incident on the second imaging device, so the corresponding portion in the grayscale image is a dark region.

  As shown in FIG. 9, the flat surface and the steep surface of the solder are both dark areas in the color image, but the brightness of both is greatly different in the grayscale image by invisible light. Therefore, it is possible to determine the inclination state of these surfaces based on the lightness in the grayscale image.

  In the inspection apparatus configured as described above, the imaging by the first imaging unit under illumination by the first illumination unit and the imaging by the second imaging unit under illumination by the second illumination unit are sequentially executed, It is desirable to simultaneously perform imaging by each imaging unit so that reflected light for the invisible light from the second illumination device does not enter the first imaging device by an optical path changing unit described later. By doing in this way, the color image under the white illumination by the diffuse reflection of each visible light can be generated for the portion where the diffuse reflection becomes dominant as in the conventional case. Therefore, it is possible to stably inspect parts other than the solder.

In a preferred aspect of the inspection apparatus, the first and second imaging means are configured as separate imaging apparatuses, and on the optical axis of the first imaging means, along the optical axis from the substrate surface. Optical path changing means for changing the optical path of the reflected light is provided so that the reflected light of the invisible light that has traveled is guided to a position where it does not enter the first imaging means. Further, the second imaging means is arranged with the optical axis aligned with the optical path changed by the optical path changing means.

  According to the above aspect, even if the reflected light with respect to the invisible light from the second illumination unit travels along the optical axis of the first imaging unit, the reflected light does not enter the first imaging unit. Since the light is incident on the second imaging unit, a color image that is not affected by invisible light can be stably generated. In addition, since each imaging unit can be driven simultaneously while performing visible light illumination and non-visible light illumination simultaneously, it is possible to reduce the inspection time.

  In another preferred aspect of the inspection apparatus, the first and second imaging means are integrated as a single imaging apparatus disposed above the substrate so that the light receiving surface faces the substrate surface, and imaging is performed. Incident light switching means for sequentially switching incident light and invisible reflected light to the image sensor of the apparatus and imaging control means for causing the imaging apparatus to perform imaging in response to switching of incident light. Further provided.

  According to the above aspect, since the first and second imaging means are integrated, the optical system can be made smaller. In addition, it is necessary to separately perform imaging under visible light illumination and imaging under non-visible light illumination. However, since the imaging target areas in each imaging match, it is easy to specify the correspondence between the two images. Can do.

In another preferred embodiment, the inspection execution means irradiates from the direction in which the elevation angle with respect to the substrate surface is the largest in the direction in which colors corresponding to the respective visible lights from the first illumination means in the color image are arranged in the inspection of the solder. A color corresponding to visible light emitted from a direction where the elevation angle with respect to the substrate surface is the smallest, and a dark region appearing at a position opposite to the color corresponding to other visible light across the color corresponding to visible light is sandwiched Then, the discrimination based on the brightness of the corresponding area in the grayscale image is executed for the dark area that appears at a position opposite to the color corresponding to the other visible light .

In the above aspect , the dark state adjacent to the portion where the color reflecting the inclined surface of the solder is aligned in the color image along the alignment direction is targeted, and the inclined state is based on the brightness of the corresponding region in the grayscale image . Therefore, even if there is a part with high specular reflectivity other than solder in the processing range, the part is misidentified as solder. It is possible to prevent separation. Therefore, the inspection accuracy can be ensured.

  According to the inspection apparatus configured as described above, in addition to a portion that appears in a color image with a color corresponding to any visible light, a solder flat surface or a steep surface that appears as a dark region where the color is not clear is also invisible light. The inclination state can be determined based on the brightness of the corresponding portion in the grayscale image. In addition, the parts other than the solder can be imaged under white illumination without being affected by illumination with non-visible light, and the accuracy of inspection can be ensured.

  Substrate appearance inspection for inspecting the suitability of the mounting state of each component, fillet shape, etc., for substrates that have undergone a series of processes (solder printing process, component mounting process, soldering process) related to the production of component mounting boards. An example of the apparatus will be described.

FIG. 1 is a block diagram showing an example of the electrical configuration of the substrate visual inspection apparatus of this embodiment.
In this inspection apparatus, two cameras 1 and two illumination units 2 are provided as means for generating an image of a substrate to be inspected (in the following, each camera 1 and each illumination unit 2 are in a correspondence relationship with each other). Combinations are distinguished by the symbols A and B). Further, the inspection apparatus is provided with an X stage unit 3, a Y stage unit 4, a control processing unit 5, and the like. Although not shown in FIG. 1, the inspection apparatus is also provided with a substrate support table for supporting the substrate to be inspected, a loading / unloading mechanism for loading / unloading the substrate, and the like.

  The X stage unit 3 supports the cameras 1A and 1B and the illumination units 2A and 2B above the substrate support table, and the Y stage unit 4 supports the substrate support table. In any of the stage portions 3 and 4, the support target can be moved along one axis. The direction of movement by one stage unit is orthogonal to the direction of movement by the other stage unit.

  The control processing device 5 includes a computer control unit 50, image input units 52A and 52B corresponding to the cameras 1A and 1B, illumination control units 53A and 53B corresponding to the illumination units 2A and 2B, an imaging control unit 51, and X. A stage drive unit 54, a Y stage drive unit 55, an input unit 56, a display unit 57, a communication interface 58, and the like are connected.

  Of the two illuminators 2A and 2B (hereinafter referred to as “first illuminator 2A” and “second illuminator 2B”), the first illuminator 2A emits visible light of red, green, and blue, The second illumination unit 2B emits infrared light. Of the two cameras 1A and 1B, the camera 1A is a color camera and images reflected light with respect to visible light from the first illumination unit 2A. The other camera 1B is an infrared camera and images reflected light with respect to the infrared light from the second illumination unit 2B to generate a grayscale image. Here, for the sake of simplicity, the cameras 1A and 1B have their field-of-view size and positional relationship adjusted so as to capture the same region, and the correspondence between pixels between images is also known. And

  The image input sections 52A and 52B are provided with interface circuits and A / D conversion circuits for receiving image signals from the corresponding cameras 1A and 1B, respectively. The image input unit 52A is provided with various circuits for each of the R, G, and B image signals.

The imaging control unit 51 causes the cameras 1 </ b> A and 1 </ b> B to simultaneously apply drive signals, thereby causing the cameras 1 </ b> A and 1 </ b> B to perform imaging at a timing synchronized with these cameras.
The illumination controllers 53A and 53B control the light quantity and lighting timing of the corresponding illumination units 2A and 2B, respectively. Further, in the illumination control unit 53A for the first illumination unit 2A, the LEDs 21R, 21G, and 21B in the illumination unit 2A (shown in FIG. 2) so that white light is obtained when the visible lights of red, green, and blue are mixed. Adjust the amount of light.

  The input unit 56 is for performing a setting operation at the time of teaching, and includes a keyboard and a mouse. The display unit 57 is for displaying an image for inspection, an inspection result, and the like, and is configured by a liquid crystal panel or the like. The communication interface 58 is used for the purpose of transmitting the inspection result to an external device.

  In the above configuration, the amount of movement of the X and Y stage units 3 and 4 necessary for aligning the camera 1 with the imaging target area assigned to the substrate is registered in the memory in the control unit 50. In addition, for each component on the board, a determination reference value related to the setting of the inspection region and the quality determination is registered. Data registered in these memories (hereinafter referred to as “inspection information”) is set by the user by using an image of a non-defective substrate during teaching.

  The control unit 50 adjusts the amount of movement of the X stage unit 3 and the Y stage unit 4 via the X stage driving unit 54 and the Y stage driving unit 55 based on the above-described inspection information, and adjusts the field of view of the cameras 1A and 1B. Align to the imaging target area of the substrate. Then, the cameras 1A and 1B are driven while illuminating the illumination units 2A and 2B under this alignment state, and an inspection image is generated. The generated inspection image is input to an image memory (not shown) in the control unit 50 via the image input units 52A and 52B. The control unit 50 processes these inspection images based on various types of inspection information, and executes inspections for parts and fillets.

FIG. 2 shows the configuration of the optical system of the inspection apparatus.
In the figure, S is a substrate to be inspected, 7 is a chip component mounted on the substrate S, and 71 is a fillet formed between the chip component 7 and the substrate S.
The cameras 1A and 1B and the illumination units 2A and 2B are supported by a support member (not shown) so as to always maintain the positional relationship shown in FIG.

The cameras 1A and 1B of this embodiment are arranged side by side above the substrate S with the optical axes 11 and 12 aligned in the vertical direction so that the light receiving surfaces thereof face the substrate surface of the substrate S, respectively.
The first illumination unit 2A has a configuration in which a plurality of LEDs 21R, 21G, and 21B that emit visible light of red, green, and blue are arranged on the inner surface of a dome-shaped housing 20 respectively. A cylindrical opening 22 projecting upward is formed at the zenith portion of the housing 20, and the LEDs 21 </ b> R, 21 </ b> G, and 21 </ b> B are arranged concentrically so as to surround the opening 22. Among these, the concentric circle of the LED 21R that emits red light is disposed at the position closest to the opening 22, and the concentric circle of the LED 21B that emits blue light is disposed at the position farthest from the opening 22, and the green between these concentric circles is green. Concentric circles of LEDs 21G that emit light are arranged.

  Said 1st illumination part 2A is arrange | positioned in the state which match | combined the opening center of the opening part 22 with the optical axis 11 of 1 A of color cameras. The relationship between the first illumination unit 2A and the color camera 1A is the same as that of the conventional color highlight optical system, but the inner surface of the opening 22 is processed into a mirror surface.

  The 2nd illumination part 2B has the planar light source 25 (henceforth "infrared light source 25") using the infrared LED (not shown), the half mirror 26, red in the rectangular parallelepiped housing | casing 24. FIG. The configuration incorporates an external reflection mirror 27 and the like. The half mirror 26 is provided on the optical axis 12 of the infrared camera 1B, and the infrared reflection mirror 27 is provided on the optical axis 11 of the color camera 1A. The infrared light source 25 is an infrared reflection mirror with the half mirror 26 in between. 27, the optical axis 28 is disposed horizontally at a position opposite to 27. The mirrors 26 and 27 are arranged in a state where the upper half faces the infrared light source 25 and the mirror surface is inclined 45 degrees with respect to the vertical direction.

Although not shown in FIG. 2, the position directly below the infrared reflection mirror 27 on the lower surface of the casing 24 of the second illumination unit 2 </ b> B depends on the outer diameter of the opening 22 of the first illumination unit 2 </ b> A. Engagement holes of different sizes are formed. Further, imaging peep holes are respectively formed at positions on the upper surface of the housing 24 immediately below the cameras 1A and 1B.
The two illumination parts 2A and 2B are connected with the relationship shown in FIG. 2 by fitting the housing 24 into the opening 22 at the position of the engagement hole. At this time, the lower end portion of the infrared reflecting mirror 27 is substantially in contact with the upper end edge of the opening 22 of the first illumination unit 2A.

  The infrared light emitted from the infrared light source 25 is transmitted through the half mirror 26, then reflected by the infrared reflection mirror 27, and passes through the opening 22 as light traveling along the optical axis of the color camera 1A. Since the inner surface of the opening 22 is a mirror surface, the infrared light emission region by the mirror surface is continuous with the red light emission region by the LED 21R, and the infrared ray has three types of visible light irradiation ranges on the substrate surface. The light irradiation range can be made continuous.

  Of the reflected light from the substrate S with respect to the infrared light, the light reflected in the direction along the optical axis 11 of the camera 1A is guided to the infrared camera 1B via the infrared reflecting mirror 27 and the half mirror 26. As described above, the mirrors 26 and 27 are constituent members of the second illumination unit 2A, and change the optical path of the reflected light of the infrared light traveling from the substrate S along the optical axis of the color camera 1A. It also functions as an optical path changing means.

  Since the infrared light from the second illumination unit 2A is irradiated almost directly onto the substrate surface S, it is reflected in the direction along the optical axis of the camera 1A out of the light regularly reflected by the fillet 71 with respect to the infrared light. It is considered that the reflected light from the horizontal or nearly horizontal surface (hereinafter referred to as “flat surface”), that is, the reflected light from the lower end when the shape of the fillet 71 is good. . Therefore, in the grayscale image (hereinafter referred to as “infrared light image”) generated by the infrared camera 1B, the brightness of the portion corresponding to the flat surface of the fillet 71 is significantly higher than the other portions.

  On the other hand, the light reflected toward the light receiving surface of the camera 1A with respect to each visible light from the first illumination unit 2A passes through the infrared reflection mirror 27 and is guided to the color camera 1A. Therefore, in the color camera 1A, it is possible to generate a color image by receiving reflected light with respect to visible light illumination from the first illumination unit 1A without being affected by illumination by infrared light.

  Further, as described above, by making the inner surface of the cylindrical body 22 of the housing 2A a mirror surface, the irradiation range of infrared light on the substrate S is made continuous with the irradiation range of each visible light. If the positional relationship between the substrate S and the optical system is adjusted so that the surface of the inclination angle corresponding to each light becomes the irradiation range of the corresponding light, the inclination angle is set by the color region corresponding to each visible light. The discriminable range and the range in which the tilt angle can be discriminated by the bright region due to regular reflection of infrared light can be continued, and the entire series of surfaces constituting the fillet can be inspected.

  In FIG. 3, a schematic diagram (a) in which the color of the specularly reflected light incident on the color camera 1A is associated with the illumination of the first illumination unit 2A for the fillet 71, and the camera 1A under the incident state described above. Schematic diagram (b) showing the color distribution state in the generated color image, and a schematic diagram showing the light and dark distribution state in the infrared light image generated by the infrared camera 1B with respect to the illumination of the second illumination unit 2B ( c) is shown in association with each other. In the color image of this example, among the inclined surfaces of the fillet 71, portions corresponding to the steepest surface at the upper end and the flat surface at the lower end are dark regions where the color is not clear. On the other hand, in the infrared light image, the flat surface that is a dark region in the color image is the brightest region, but the brightness is slightly reduced in a portion that is a red region. Further, the portion with a steep slope becomes a dark region.

A table as shown in FIG. 4 is stored in the memory of the control unit 50. This table classifies inclination angles into five levels according to combinations of colors in a color image and brightness in an infrared light image. The inclination angles corresponding to the respective levels are continuous, the one having the steepest inclination is level A, and thereafter, the inclination becomes gentler in the order of B, C, D, and E. Also, a color image having a remarkably low brightness is not “color” but “dark” (meaning a dark region).
The range of the inclination angle corresponding to each inclination level A to E is derived from the range of the irradiation angle of each illumination light.

  In the inspection for the fillet, the control unit 50 refers to the above table according to the combination of the color in the color image and the brightness level of the infrared image, and identifies the pixel corresponding to each inclination level. As a result, only a color image becomes a dark region, and even a portion where the inclination angle cannot be determined is a surface with a steep inclination level A or a flat inclination level E depending on the degree of brightness and darkness in the infrared light image. It can be determined whether there is.

  Each color in the color image is extracted by binarizing each R, G, B image data with a predetermined threshold value. Similarly, light / dark regions in the infrared light image are also extracted by binarization. As the threshold value for extracting the bright region, a value that can be divided into “bright” and “slightly bright” in FIG. 3 is set, and for the threshold value for extracting the dark region, “slightly” is set. A value that can be divided into “bright” and “dark” is set.

As described above, according to the inspection apparatus of this embodiment, it is possible to determine the inclination angle for a range wider than the detection range using only the color highlight illumination, thereby improving the accuracy of the fillet inspection. it can.
In addition, as for the part where diffuse reflection other than solder is dominant, white illumination by diffuse reflection can be performed as in the conventional case, so that a color image in which the original color and shape clearly appear can be generated. . Therefore, it is possible to ensure the accuracy of the inspection for the parts other than the fillet.

Next, the flow of inspection performed on one substrate will be described with reference to FIG.
First, in step 1, when a substrate to be inspected is loaded onto the substrate support table, in step 2, the operations of the X and Y table units 3 and 4 are controlled to register the fields of view of the cameras 1A and 1B. The image is aligned with the imaged target area (step 2). When the alignment is completed, in step 3, the cameras 1A and 1B are simultaneously driven under illumination by the illumination units 2A and 2B to perform imaging for inspection.

  When the imaging is completed, the three types of images constituting the color image (grayscale images for each of R, G, and B) and the infrared light image are set as the processing target images, and the first inspection is performed on these images. An inspection area for the target part is set (step 4).

In this setting process, first, a window called “part extraction window” is set for a part to be inspected based on the inspection information in the memory in a range that reliably includes this part and the nearby land. Then, from the color image in the component extraction window, a place where each color of red, green, and blue appears is specified as a land, and a land window is set for this place.
The size and set number of land windows are registered in advance as inspection information, and usually a plurality of land windows are set. In step 4, a component body window is set between the land windows. The size of this window is also registered in advance as inspection information.

  In step 5, the color of the component is detected by binarization for only the color image in the component main body window, and the presence / absence of the component and the suitability of the position and inclination are determined based on the result.

  In step 6, the land window is subjected to a fillet inspection by image processing using both a color image and an infrared image. Specifically, paying attention to the set land windows in order, the processing of steps 6a to 6d shown on the right side of FIG. 5 is executed for each window.

  In step 6a, the color area corresponding to each visible light is extracted for the color image and the light and dark areas are extracted for the infrared light image by binarization for the land window under consideration. In step 6b, for each pixel in the land window, the result of the above binarization process and the table shown in FIG. 4 are collated to identify pixels corresponding to the respective inclination levels A to E.

  In step 6c, the position and area (number of pixels) are measured for each pixel group (region) for each inclination level. In step 6d, the quality of the shape of the fillet in the land window is determined by comparing each measured value with a registered reference value.

  When the processing in all the land windows is completed, step 6e becomes “NO” and the fillet inspection is completed. Thereafter, the parts inspection and the fillet inspection are executed for all the parts included in the processing target image by the processes of steps 4, 5, and 6 in the same manner as described above.

  Note that the inspection executed in step 5 is not limited to component inspection, and for example, the presence or absence of defects such as electrode float may be determined.

  When the inspection for the component in the processing target image is completed, Step 7 is “YES”. Here, if there is another imaging target region, the process returns from step 8 to step 2, and the processing after the alignment of the cameras 1A and 1B is executed again.

  When the processing for all the imaging target regions is completed, step 8 is “YES”, the process proceeds to step 9, and a series of inspection results are integrated and output. After this, a process (Step 10) for unloading the inspected substrate is performed, and then the process ends.

  In the above embodiment, in order to simplify the algorithm, for the pixels appearing in red, green, and blue colors, the inclination level is determined by combining the brightness of infrared light. It may be considered that the determination of the typical inclination level is performed based on the illumination light irradiation direction corresponding to the color in the color image. In a color image, for pixels in which a color corresponding to visible light illumination appears, discrimination using the color is performed without performing a determination using an infrared light image, and the color image becomes a dark region. The same inspection result can be obtained even if the discrimination is performed only on the pixel based on the brightness of the infrared light image.

  In addition, the land window is set to be wider or the setting position is slightly shifted, so that misidentification is prevented when a portion with high specular reflectivity other than solder (for example, a silk print pattern) is included in the window. Therefore, the inclination level determination target may be specified based on the relationship between the color arrangement corresponding to each visible light and the dark region.

  That is, in the direction in which the colors corresponding to each visible light in the color image are arranged, the position facing the other color area across the red area and the other color area across the blue area The brightness state of the corresponding area in the infrared light image related to the dark area is determined for the dark area in the area. In this case, for the former dark region, when the corresponding region in the infrared light image is a bright region, for the latter dark region, when the corresponding region in the infrared light image is a dark region, the surface It can be determined that the state is good.

  Furthermore, in the inspection apparatus having the above configuration, it is possible to determine the suitability of the component by detecting the glossiness using the infrared light from the second illumination unit 2B. Since the upper surface of the component main body is flat, if the glossiness of the package that makes up the main body increases, it appears as a dark area in the image captured under white illumination and distinguishes it from other components of the same color Becomes difficult. However, according to the grayscale image obtained by the second camera 1B, a brighter image is obtained as the glossiness increases. Therefore, by combining the color check with the color image and the glossiness check with the infrared light image, the component inspection can be performed. Accuracy can be increased.

In the optical system according to the above-described embodiment, since the camera 1B and the second illumination unit 2B are incorporated, the configuration becomes more complicated than the conventional one, but the configuration of the first illumination unit 2A itself is the illumination of the conventional color highlight illumination. It is the same as the device. In addition, since the height of the first illumination unit 1A is the same as the conventional one and the second illumination unit 2B can be arranged in the space between the illumination unit 1A and the camera 1A, the configuration of the optical system becomes large. Can be prevented.
Further, the configuration relating to the irradiation and imaging of the infrared light is not limited to the above, and the positions of the infrared light source 25 and the infrared camera 1B may be reversed.

  Further, in the above embodiment, imaging with visible light illumination and imaging with infrared illumination are performed simultaneously, but each imaging may be performed in order. When imaging is performed separately as described above, the configuration of the optical system can be simplified and made smaller by integrating the two cameras 1A and 1B as shown in FIG.

  In the configuration example of FIG. 6, a camera 10 having a function of generating a color image and an infrared light image is used instead of the cameras 1A and 1B so that the light receiving surface faces the substrate surface in the same manner as the camera 1A. Deploy. The configuration of the first illumination unit 2A is the same as that shown in FIG. 2, but in the second illumination unit 2B, the infrared reflection mirror 27 is eliminated, the half mirror 26 is provided on the optical axis 11 of the camera 10, and the infrared light source 25 is provided. Is also arranged at a position close to the optical axis 11. Further, a filter switching mechanism 6 is disposed between the second illumination unit 2B and the camera 1A.

  The filter switching mechanism 6 includes a plate-like filter support portion 61, a rotary shaft 62 that passes through the center position of the filter support portion 61, a motor (not shown) connected to the rotary shaft, and the like. The filter support 61 is formed with a pair of windows (not shown) having a symmetrical relationship with respect to a straight line passing through the rotation shaft 62, with a visible light transmission filter 63 in one window and a red in the other. An external light transmission filter 64 is provided. Each window part and the filters 63 and 64 are each formed in the size according to the light-receiving surface of the camera 10, and the position of the filter support part 61 is set so that one of the filters is located directly below the light-receiving surface of the camera 10. Has been adjusted.

  In the above configuration, the control unit 50 switches the filter located immediately below the light receiving surface of the camera 10 by rotating the filter support unit 61 in units of 180 degrees, and causes the camera 10 to perform imaging each time the switching is performed.

  The imaging element of the camera 10 includes a cell that is sensitive to red, green, and blue visible light and a cell that is sensitive to infrared light. When the visible light transmission filter 63 is arranged directly below the light receiving surface and imaging is performed, the control unit 50 generates a color image using a signal from a cell corresponding to visible light, and an infrared light directly below the light receiving surface. When the light transmission filter 64 is disposed and imaging is performed, an infrared light image is generated using a signal from a cell corresponding to infrared light. Then, parts inspection and fillet inspection are executed on these images by executing the same processing as steps 4, 5, and 6 in FIG.

According to the above configuration, since the imaging needs to be performed twice for each imaging target region, the inspection time becomes long, but the field of view in the two imagings can be matched. It becomes easy to specify the correspondence between the optical images. Even when each image is displayed for visual verification of the image, it is possible to display an image with no parallax and easy to grasp the correspondence.
The filter switching mechanism 6 can be incorporated in front of the image sensor inside the camera 10.

7 and 8 show an example in which the optical system is downsized by changing the configuration of the second illumination unit 2B.
In these embodiments, as the second illumination unit 2B, a thin plate-shaped illumination panel 29 that is a combination of a substrate on which infrared LEDs are wired, a light guide diffusion plate, and the like is used. In addition to the function of emitting planar light from the front surface, the illumination panel 29 has a function of transmitting reflected light irradiated to the front surface to the back surface side through the light guide diffusion plate. In addition, as an illumination panel having such a function, for example, LFX series of CCS Co., Ltd. is known.

  The illumination panel 29 is arranged so that the plate surface is horizontal and closes the opening 22 of the first illumination unit 2A. In the embodiment of FIG. 7, the color camera 1A is arranged in the same state as in the example of FIG. 2, and the infrared camera 1B is arranged with its optical axis 12 orthogonal to the optical axis 11 of the camera 1A. An infrared reflection mirror 27 is disposed at a point where the optical axes 11 and 12 intersect.

  According to said structure, the infrared light from the illumination panel 29 advances along the optical axis 11 of the camera 1A, and is irradiated to the substrate surface. At this time, the infrared light that has been specularly reflected by the flat surface of the fillet 71 and traveled along the optical axis 11 is transmitted through the illumination panel 29, and then the optical path is changed by the infrared reflecting mirror 27 to be guided to the infrared camera 1 </ b> B. It is burned. On the other hand, the light reflected in the direction along the optical axis 11 with respect to the visible light illumination from the first illumination unit 2A passes through the illumination panel 29 and the infrared reflection mirror 27 and is guided to the color camera 1A.

  In the embodiment of FIG. 8, as in the example of FIG. 6, the camera 10 having the function of generating a color image and an infrared light image and the filter switching mechanism 6 are used. In this example, both the half mirror 26 and the infrared reflection mirror 27 are not required, so that the distance between the illumination units 2A and 2B and the camera 10 can be reduced. Therefore, it is possible to easily deal with tall parts and take an image close to the substrate S.

In each of the configuration examples shown in FIGS. 2, 6, 7, and 8, the first illumination unit 2A emits three types of visible light of red, green, and blue from directions with different elevation angles with respect to the substrate surface. However, the number of emitted visible lights may be two types. Also in this case, it is necessary to set the illumination color so that white light is generated when each visible light is mixed, for example, green and magenta which is a mixed color of red and green are used as illumination colors.
The space occupied by the first illumination unit 2A is larger than the other parts of the optical system. However, if the illumination colors are two types as described above, the housing 20 can be downsized. Also in this case, by introducing the second illumination unit 2B shown in each of the above examples and generating an infrared light image, it is possible to determine the detection angle of the part that cannot be determined by color highlight illumination, It is possible to prevent the accuracy from being lowered.

It is a block diagram which shows the structural example of a board | substrate external appearance inspection apparatus. It is explanatory drawing which shows the structural example of an optical system. It is explanatory drawing which shows the state of the visible light guide | induced to a color camera from a fillet in association with a color image and an infrared light image. It is a table which shows the example of classification of an inclination level. It is a flowchart which shows the flow of a test | inspection. It is explanatory drawing which shows the other structural example of an optical system. It is explanatory drawing which shows the other structural example of an optical system. It is explanatory drawing which shows the other structural example of an optical system. It is explanatory drawing which shows the example of the image produced | generated by the color highlight illumination with respect to a hemispherical solder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Color camera 1B Infrared camera 2A 1st illumination part 2B 2nd illumination part 11 Optical axis of color camera 21 (R, G, B) LED (visible light source)
25 Infrared light source 26 Half mirror 27 Infrared reflecting mirror 29 Illumination panel 50 Control unit

Claims (4)

A device for visual inspection of a printed circuit board after soldering,
A first imaging means that is arranged above a substrate to be inspected so that a light receiving surface faces the substrate surface, and generates a color image of the substrate;
Irradiating the substrate surface with a plurality of visible lights that are different from each other and become white light when mixed with each other from a direction in which the elevation angle with respect to the substrate surface is different and oblique to the optical axis of the first imaging means First illumination means;
Second illumination means for irradiating the substrate surface with invisible light from a direction along the optical axis of the first imaging means ;
The first imaging means is arranged with the optical axis and field of view aligned, and the reflected light from the substrate surface with respect to the invisible light irradiated from the second illumination means is received, and the incident state of the reflected light Second imaging means for generating a gray image reflecting
The color image generated by the first imaging unit and the grayscale image generated by the second imaging unit are used to inspect the solder on the substrate, and the portions other than the solder in the color image are inspected. An inspection execution means for executing an inspection using an image of a corresponding location,
In the inspection for solder, the inspection execution unit is a portion represented by a color corresponding to the illumination light from the first illumination unit in the color image among the portions corresponding to the solder in the color image and the grayscale image. In contrast, the inclination angle is determined based on the illumination direction of the illumination light corresponding to the appearing color, and it is a dark region in the color image, and is represented by a lightness exceeding the first threshold value in the grayscale image. Is determined to be a surface that is gentler than the range of inclination angles determined by the color corresponding to the illumination light from the first illumination means, and becomes a dark region in the color image, A portion represented by a lightness lower than a second threshold value that is lower than the first threshold value is steeper than a range of inclination angles determined by the color corresponding to the illumination light from the first illumination means. determined to be a face That board appearance inspection apparatus. The first and second imaging means are configured as separate imaging devices, and on the optical axis of the first imaging means, reflection of invisible light traveling along the optical axis from the substrate surface is reflected. An optical path changing means for changing the optical path of the reflected light is provided so that light is guided to a position where the light does not enter the first imaging means, and the first optical axis is aligned with the optical path changed by the optical path changing means . The board | substrate external appearance inspection apparatus of Claim 1 with which 2 imaging means are arrange | positioned.   The first and second imaging means are integrated as a single imaging device disposed above the substrate so that the light receiving surface faces the substrate surface, and visible light is applied to the imaging device of the imaging device. And an incident light switching unit that sequentially switches and injects each reflected light of invisible light, and an imaging control unit that causes the imaging device to perform imaging in response to switching of the incident light. 1. A substrate visual inspection apparatus according to 1. In the inspection of the solder, the inspection execution unit radiates visible light from a direction in which the elevation angle with respect to the substrate surface is the largest in the direction in which colors corresponding to the visible light from the first illumination unit in the color image are arranged. A dark region that appears at a position opposite to the color corresponding to other visible light with the color corresponding to the other, and another visible across the color corresponding to the visible light irradiated from the direction with the smallest elevation angle with respect to the substrate surface The board | substrate external appearance inspection apparatus of Claim 1 which performs discrimination | determination based on the brightness of the corresponding area | region in the said grayscale image for the dark area which appeared in the position facing the color corresponding to light .

Images