Patent Publication Number: US-2021172884-A1

Title: Inspection device and inspection method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese patent application No. 2019-218173, filed on Dec. 2, 2019, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to an inspection device and an inspection method 
     BACKGROUND ART 
     In a manufacturing process of electronic equipment, a shape of solder printed on a substrate is inspected by using an appearance inspection device. The appearance inspection device determines quality of a state of the solder by using an image obtained by imaging the state of the solder printed on the substrate. 
     For example, in Japanese Patent No. 5566707, an inspection window is set in a region to be inspected, and various determinations are made on an electronic component in the set inspection window. 
     The appearance inspection of the solder printed on the substrate can be automatically performed since a position where the solder is printed can be specified if design data (for example, Gerber data) including wiring information of the substrate is available. However, when the design data is not available, it is necessary to manually set an inspection window to specify an inspection position. 
     Therefore, when the design data is not available, it takes time to set the inspection window, and the work efficiency of the solder appearance inspection process may deteriorate. 
     SUMMARY OF INVENTION 
     According to the present disclosure, there is provided an inspection device comprises an image acquisition unit configured to acquire images obtained by imaging, under at least two illumination conditions with different brightness, solder normally printed on a substrate, and an image processing unit configured to specify a shape of the solder based on a difference in brightness between the images acquired by the image acquisition unit, and generate, based on the shape of the solder, inspection data used for inspecting a state of the solder printed on the substrate. 
     According to the present disclosure, the work efficiency of appearance inspection of the solder printed on the substrate is improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram schematically showing a production line of an electronic equipment according to an embodiment. 
         FIG. 2  is a diagram schematically showing a solder inspection device according to the embodiment. 
         FIG. 3  is a functional block diagram showing an example of a configuration of a control device according to the embodiment. 
         FIG. 4  is a flowchart showing an example of a method for generating inspection data according to the embodiment. 
         FIG. 5  is a diagram showing an example of a substrate imaged at a first inclination angle according to the embodiment. 
         FIG. 6  is a diagram showing an example of a substrate imaged at a second inclination angle according to the embodiment. 
         FIG. 7  is a diagram showing an example of a difference image between the image taken at the first inclination angle and an image taken at the second inclination angle according to the embodiment. 
         FIG. 8  is a diagram showing an example of inspection data according to the embodiment. 
         FIG. 9  is a flowchart showing an example of an inspection method according to an embodiment. 
         FIG. 10  is a block diagram showing a computer system according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited thereto. Components of the embodiment to be described below can be combined as appropriate. A part of the components may not be used. 
     In the embodiment, a XYZ Cartesian coordinate system is defined, and a positional relationship of each part will be described with reference to the XYZ Cartesian coordinate system. A direction parallel to an X-axis in a horizontal plane is defined as an X direction. A direction parallel to a Y-axis in the horizontal plane that is orthogonal to the X-axis is defined as a Y direction. A direction parallel to a Z-axis that is orthogonal to the horizontal plane is defined as a Z direction. A plane including the X-axis and the Y-axis is appropriately referred to as an XY plane. The XY plane is parallel to the horizontal plane. The Z-axis is parallel to a vertical line. The Z direction is an upper-lower direction. A +Z direction is an upper direction and a −Z direction is a lower direction. 
     [Production Line] 
       FIG. 1  is a diagram schematically showing a production line  1  of electronic equipment according to an embodiment. As shown in  FIG. 1 , the production line  1  includes a printing machine  2 , a solder inspection device  3 , an electronic component mounting device  4 , a reflow furnace  5 , and an appearance inspection device  6 . 
     The printing machine  2  prints cream solder on a substrate on which electronic components are to be mounted. 
     The solder inspection device  3  determines quality of a state of the cream solder printed on the substrate. The solder inspection device  3  generates, based on an image of cream solder normally printed on the substrate, inspection data for determining quality of the state of the cream solder. The solder inspection device  3  determines, based on the inspection data, the quality of the state of the cream solder printed on the substrate. The solder inspection device  3  determines the quality of the state of the cream solder by comparing the inspection data with the state of the cream solder printed on the substrate. 
     The electronic component mounting device  4  mounts electronic components on the substrate on which the cream solder is printed. The reflow furnace  5  heats the substrate on which the electronic components are mounted to melt the cream solder. The melted cream solder in the reflow furnace  5  is cooled, and thus the electronic components are soldered to the substrate. 
     The appearance inspection device  6  inspects whether the electronic components are suitably mounted on the substrate. The appearance inspection device  6  inspects whether correct electronic components are mounted on the substrate. 
     [Solder Inspection Device] 
     A configuration of the solder inspection device  3  according to the present embodiment will be described with reference to  FIG. 2 .  FIG. 2  is a schematic diagram showing an example of the configuration of the solder inspection device  3  according to the embodiment. 
     As shown in  FIG. 2 , the solder inspection device  3  includes a substrate holding device  31  that holds a substrate P on which cream solder is printed; an illumination device  32  by which the cream solder printed on the substrate P can be illuminated under a plurality of illumination conditions; an imaging device  33  that images the cream solder mounted on the substrate P; a control device  7  including a computer system; a display device  8  capable of displaying display data; and an input device  9  that is operated by an operator. 
     The substrate holding device  31  holds the substrate P on which the cream solder is printed. The substrate holding device  31  includes a base member  31 A, a holding member  31 B that holds the substrate P, and an actuator  31 C that generates power to move the holding member  31 B. The base member  31 A movably supports the holding member  31 B. The holding member  31 B holds the substrate P such that the cream solder printed on a surface of the substrate P and the imaging device  33  face each other. In a state of holding the substrate P, the holding member  31 B is movable in an X direction by operating the actuator  31 C. For example, when the holding member  31 B carries in the substrate P, position adjustment between the imaging device  33  and the substrate P in the X direction is performed by operating the actuator  31 C. As to be described later, the positions of the imaging device  33  and the substrate P in the XY direction when the imaging device  33  images the substrate P can be adjusted by moving the imaging device  33  in the XY direction. 
     The illumination device  32  illuminates the cream solder printed on the substrate P with illumination light while the substrate P is held by the substrate holding device  31 . The cream solder is illuminated under each of the plurality of illumination conditions of the illumination device  32 . The illumination device  32  is disposed above the substrate holding device  31 . The illumination device  32  includes a plurality of light sources  34  by which the cream solder can be illuminated under different illumination conditions, and a support member  32 S that supports the plurality of light sources  34 . 
     Each of the plurality of light sources  34  has an annular shape. As the plurality of light sources  34 , for example, light emitting diodes (LEDs) are exemplified. The plurality of light sources  34  emit white light as illumination light. The support member  32 S is disposed at least on a part of a periphery of the plurality of light sources  34 . The illumination light emitted by the plurality of light sources  34  is not limited to white light, and may be red light, blue light, or the like. 
     In the embodiment, the light sources  34  include a first light source  34 A having a first inner diameter, a second light source  34 B having a second inner diameter larger than the first inner diameter, and a third light source  34 C having a third inner diameter larger than the second inner diameter. Among the plurality of light sources  34 , the first light source  34 A is disposed at a position farthest from the substrate holding device  31 , the second light source  34 B is disposed at a position farthest from the substrate holding device  31  next to the first light source  34 A, and the third light source  34 C is disposed at a position closest to the substrate holding device  31 . That is, among the plurality of light sources  34 , the first light source  34 A is disposed at the highest position, the second light source  34 B is disposed at the highest position next to the first light source  34 A, and the third light source  34 C is disposed at the lowest position. 
     The illumination condition includes an incident angle θ of the illumination light incident on the cream solder. An incident angle θ 1  at which illumination light emitted from the first light source  34 A is incident on the cream solder, an incident angle θ 2  at which illumination light emitted from the second light source  34 B is incident on the cream solder, and an incident angle θ 3  at which illumination light emitted from the third light source  34 C is incident on the cream solder are different. The cream solder printed on the substrate P is irradiated with the illumination light of the illumination device  32  at each of the plurality of incident angles θ. 
     In the following description, the illumination condition for illuminating the cream solder with the illumination light emitted from the first light source  34 A may be appropriately referred to as a first illumination condition. The illumination condition for illuminating the cream solder with the illumination light emitted from the second light source  34 B may be appropriately referred to as a second illumination condition. The illumination condition for illuminating the cream solder with the illumination light emitted from the third light source  34 C may be appropriately referred to as a third illumination condition. 
     When the illumination light is emitted from the first light source  34 A, the illumination light is not emitted from any of the second light source  34 B and the third light source  34 C. When the illumination light is emitted from the second light source  34 B, the illumination light is not emitted from any of the third light source  34 C and the first light source  34 A. When the illumination light is emitted from the third light source  34 C, the illumination light is not emitted from any of the first light source  34 A and the second light source  34 B. 
     The imaging device  33  images the cream solder mounted on the substrate P and acquires an image of the cream solder. The imaging device  33  is disposed above the illumination device  32 . The imaging device  33  includes an optical system  33 A and an image sensor  33 B that acquires the image of cream solder via the optical system  33 A. In the embodiment, an optical axis AX of the optical system  33 A is parallel to the Z-axis. The optical axis AX of the optical system  33 A is disposed inside the annular light sources  34 . As the image sensor  33 B, at least one of a Couple Charged Device (CCD) image sensor and a Complementary Metal Oxide Semiconductor (CMOS) image sensor is exemplified. The imaging device  33  can acquire a color image of the cream solder. The imaging device  33  may be configured by a monochrome camera. In this case, the imaging device  33  acquires a monochrome image of the cream solder. 
     The imaging device  33  is disposed, for example, on a moving device  35  above the illumination device  32 . The moving device  35  has a holding member  35 A and an actuator  35 B. The holding member  35 A supports a head portion of the imaging device  33 . In a state of supporting the imaging device  33 , the holding member  35 A is movable in the XY plane by operating the actuator  35 B. By moving the holding member  35 A in the XY plane in a state where the imaging device  33  is instructed, position adjustment between the imaging device  33  and the substrate P in the XY plane during imaging of the substrate P can be performed. When the imaging device  33  moves in the XY plane, the illumination device  32  also moves in the XY plane together with the imaging device  33 . 
     The imaging device  33  images the cream solder in a state where the cream solder is illuminated by the illumination device  32 . The imaging device  33  images the cream solder illuminated under each of the first illumination condition, the second illumination condition, and the third illumination condition. The light sources  34  are disposed outside a field of view of the imaging device  33 . The imaging device  33  images the cream solder through a space inside the light sources  34 . 
     The holding member  35 A moves in the XY plane. The holding member  35 A moves such that the cream solder printed on the substrate P is disposed in the field of view of the imaging device  33 . The imaging device  33  images each of a plurality of regions of the substrate P each time a relative position in the XY plane between the substrate P and the field of view of the imaging device  33  is adjusted. Therefore, the imaging device  33  can acquire images of the cream solder on the entire substrate P. 
     The control device  7  controls the substrate holding device  31 , the illumination device  32 , and the imaging device  33 . The control device  7  includes an arithmetic processing device including a processor such as a Central Processing Unit (CPU); and a storage device including a storage and a memory such as a Read Only Memory (ROM) or a Random Access Memory (RAM). The arithmetic processing device performs arithmetic processing according to a computer program stored in the storage device. Further, the control device  7  may be implemented by, for example, an integrated circuit such as an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA). 
     The control device  7  controls the substrate holding device  31  to adjust the relative position between the substrate P held by the holding member  31 B and the field of view of the imaging device  33 . The control device  7  controls the illumination device  32  to adjust the illumination condition of the cream solder mounted on the substrate P. The control device  7  controls the imaging device  33  to control imaging conditions including at least one of a timing of imaging the cream solder, a shutter speed, and an aperture of the optical system  33 A. 
     The control device  7  controls the illumination device  32  to illuminate the cream solder mounted on the substrate P in each of the plurality of illumination conditions. The control device  7  controls the imaging device  33  to acquire a plurality of images of the cream solder illuminated under the plurality of illumination conditions. 
     The control device  7  controls the illumination device  32  to illuminate, in the first illumination condition, the cream solder with the illumination light emitted from the first light source  34 A. The control device  7  controls the illumination device  32  to illuminate, in the second illumination condition, the cream solder with the illumination light emitted from the second light source  34 B. The control device  7  controls the illumination device  32  to illuminate, in the third illumination condition, the cream solder with the illumination light emitted from the third light source  34 C. The control device  7  acquires an image of the cream solder when illuminated under the first illumination condition, an image of the cream solder when illuminated under the second illumination condition, and an image of the cream solder when illuminated under the third illumination condition. The image of the cream solder when illuminated under the first illumination condition may be referred to as a first image. The image of the cream solder when illuminated under the second illumination condition may be referred to as a second image. The image of the cream solder when illuminated under the third illumination condition may be referred to as a third image. 
     The control device  7  generates a difference image in which a difference in brightness between the first image and the second image is calculated. The control device  7  generates a difference image in which a difference in brightness between the first image and the third image is calculated. The control device  7  generates a difference image in which a difference in brightness between the second image and the third image is calculated. The brightness of an image is brilliance, luminance, or the like of the image. 
     The control device  7  executes binarization processing of converting the generated difference image into a two-step color tone of black and white, and generates a binary image. For example, the control device  7  converts a region having luminance exceeding a predetermined threshold value into white and a region having luminance below a predetermined threshold value into black for each pixel in the difference image, so as to generate the binary image. In the present embodiment, the color of the binary image is not limited to black and white, and other color combinations may be used. 
     The control device  7  extracts an edge of the cream solder based on the binary image. The control device  7  extracts the black and white regions as the edge of the cream solder based on the binary image. The control device  7  specifies a shape of the cream solder based on the extracted edge. 
     The control device  7  generates, based on the shape of the cream solder, inspection data for determining quality of the shape of the cream solder. The control device  7  generates, based on the shape of the cream solder normally printed on the substrate, inspection data for determining the quality of the shape of the cream solder. 
     The control device  7  determines the quality of the shape of the cream solder printed on the substrate. The control device  7  determines, based on the inspection data, the quality of the shape of the cream solder printed on the substrate. 
     The display device  8  has a display screen for displaying display data. As the display device  8 , a flat panel display such as a Liquid Crystal Display (LCD) or an Organic Electroluminescence Display (OELD) is exemplified. An operator can check the display screen of the display device  8 . For example, the operator can check a state of the cream solder printed on the substrate P on the display screen of the display device  8 . 
     The input device  9  is operated by an operator. The input device  9  generates input data by being operated by the operator. The input data generated by the input device  9  is output to the control device  7 . As the input device  9 , at least one of a computer keyboard, a mouse, a button, a switch, and a touch panel is exemplified. 
     [Control Device] 
     A configuration of the control device according to the present embodiment will be described with reference to  FIG. 3 .  FIG. 3  is a functional block diagram showing an example of the configuration of the control device according to the present embodiment. 
     As shown in  FIG. 3 , the control device  7  includes an input data acquisition unit  71 , a carry-in position control unit  72 , an illumination control unit  73 , a relative position control unit  74 , an imaging control unit  75 , an image acquisition unit  76 , an image processing unit  77 , a determination unit  78 , a storage unit  79 , and a display control unit  80 . 
     The input data acquisition unit  71  acquires the input data generated by operating the input device  9 . 
     The carry-in position control unit  72  outputs a control instruction to the substrate holding device  31  to adjust a relative position in the X direction between the imaging device  33  and the holding member  31 B that holds the substrate P during carry-in of the substrate P. The carry-in position control unit  72  adjusts a relative position in the X direction between the cream solder printed on the substrate P and the field of view of the imaging device  33  during carry-in of the substrate P. 
     The illumination control unit  73  outputs a control instruction to the illumination device  32  to adjust the illumination condition when the cream solder printed on the substrate P is illuminated with the illumination light. The illumination control unit  73  controls the illumination device  32  such that the cream solder is to be illuminated under at least two of the first illumination condition, the second illumination condition, and the third illumination condition. 
     The relative position control unit  74  outputs a control instruction to the moving device  35  to cause the moving device  35  to move in the XY plane, and thus the relative position in the XY plane between the holding member  31 B that holds the substrate P and the imaging device  33  is adjusted. The relative position control unit  74  adjusts the relative position in the XY plane between the cream solder printed on the substrate P and the field of view of the imaging device  33 . 
     The imaging control unit  75  outputs a control instruction to the imaging device  33  to control imaging conditions including at least one of the timing of imaging the cream solder, the shutter speed, and the aperture of the optical system  33 A. 
     The image acquisition unit  76  acquires a plurality of images of the cream solder in a state of being printed on the substrate P while being illuminated by the illumination device  32  under the plurality of illumination conditions. The image acquisition unit  76  acquires the plurality of images of the cream solder that is imaged by the imaging device  33  while being illuminated under the plurality of illumination conditions. The image acquisition unit  76  acquires the first image of the cream solder when illuminated under the first illumination condition, the second image of the cream solder when illuminated under the second illumination condition, and the third image of the cream solder when illuminated under the third illumination condition. 
     The image processing unit  77  performs image processing on the images acquired by the image acquisition unit  76 . The image processing unit  77  specifies the shape of the cream solder based on a difference in brightness between the images acquired by the image acquisition unit  76 . The image processing unit  77  generates, based on the shape of the cream solder, inspection data to be used for inspecting a state of the cream solder printed on the substrate P. 
     Specifically, the image processing performed by the image processing unit  77  includes processing of calculating the difference in brightness between two images among the first image, the second image, and the third image acquired by the image acquisition unit  76 , and generating a difference image. The image processing includes processing of generating a binary image based on the difference image. The image processing includes processing of extracting edges of regions having different colors based on the binary image to specify the shape of the cream solder. The image processing includes processing of generating, based on the specified shape of the cream solder, inspection data for determining the quality of the state of the cream solder printed on the substrate. The inspection data is generated based on an image of the substrate P on which the cream solder is normally printed. The image processing unit  77  stores the generated inspection data into the storage unit  79 . 
     The determination unit  78  determines various states of the cream solder printed on the substrate. The determination unit  78  determines the quality of the state of the cream solder printed on the substrate. The determination unit  78  compares the image of the cream solder acquired by the image acquisition unit  76  with the inspection data stored in the storage unit  79 , and determines the quality of the state of the cream solder printed on the substrate. 
     The storage unit  79  stores various types of information. The storage unit  79  stores inspection data for determining the quality of the state of the cream solder printed on the substrate. The storage unit  79  can be implemented by, for example, a semiconductor memory element such as a Random Access Memory (RAM) or a flash memory, or a storage device such as a hard disk or a solid state drive. 
     The display control unit  80  displays various types of display data on the display device  8 . The display control unit  80  displays, on the display device  8 , the image of the cream solder acquired by the image acquisition unit  76 . The display control unit  80  displays, on the display device  8 , the image of the cream solder that is image-processed by the image processing unit  77 . The display control unit  80  displays a determination result of the determination unit  78  on the display device  8 . 
     [Method for Generating Inspection Data] 
     A method for generating the inspection data according to the embodiment will be described with reference to  FIG. 4 .  FIG. 4  is a flowchart showing an example of the method for generating the inspection data according to the embodiment. 
     The image acquisition unit  76  acquires, from the imaging device  33 , an image of the substrate P irradiated with the illumination light at a first inclination angle (step S 10 ). The first inclination angle is a relatively steep angle. In the example shown in  FIG. 2 , the image acquisition unit  76  acquires, from the imaging device  33 , an image of the substrate P irradiated with the illumination light of the first light source  34 A. The image acquisition unit  76  acquires, from the imaging device  33 , an image of the substrate P irradiated with the illumination light of the second light source  34 B. 
       FIG. 5  shows an image IM 1  of the substrate P that is imaged by the imaging device  33  while being irradiated with the illumination light at the first inclination angle. In  FIG. 5 , the image of the substrate P that is imaged by the imaging device  33  while being irradiated with the illumination light of the first light source  34 A is shown. 
     The substrate P is divided into a plurality of regions, and the imaging device  33  images the plurality of regions. The imaging device  33  images one region of the substrate P, and images a next region after the next region of the substrate P is moved to the field of view of the imaging device  33  by the substrate holding device  31 . For example, the substrate P is divided into three regions, a region L 1 , a region L 2 , and a region L 3 , and the imaging device  33  images the three regions of the substrate P. The image acquisition unit  76  acquires images of the three regions, the region L 1 , the region L 2 , and the region L 3 . The image acquisition unit  76  synthesizes the images of the region L 1 , the region L 2 , and the region L 3  to obtain an image of the entire substrate P. Cream solder SD 1  to SD 15  are printed on the substrate P. Silk M is printed on the substrate P as guides. The substrate P does not limit the substrate to which this embodiment is applied. 
     The image acquisition unit  76  acquires, from the imaging device  33 , an image of the substrate P irradiated with the illumination light at a second inclination angle (step S 11 ). The second inclination angle is a relatively gentle angle. In a case where the illumination light of the first inclination angle is from the first light source  34 A, the image acquisition unit  76  acquires, from the imaging device  33 , the image of the substrate P irradiated with the illumination light of the second light source  34 B or the third light source  34 C. In a case where the illumination light of the first inclination angle is from the second light source  34 B, the image acquisition unit  76  acquires, from the imaging device  33 , the image of the substrate P irradiated with the illumination light of the third light source  34 C. 
       FIG. 6  shows an image IM 2  of the substrate P that is imaged by the imaging device  33  while being irradiated with the illumination light at the second inclination angle. The method for imaging the substrate P irradiated with the illumination light at the second inclination angle is the same as the method for imaging the substrate P irradiated with the illumination light at the first inclination angle. 
     When the image IM 1  of  FIG. 5  is compared with the image IM 2  of  FIG. 6 , a way of reflecting the illumination light is different. In particular, the image IM 1  and the image IM 2  differ in the way of reflecting the illumination light in the cream solder SD 1  to SD 15 . Specifically, the cream solder SD 1  to SD 15  in the image IM 1  reflect more light than the cream solder SD 1  to SD 15  in the image IM 2 . 
     The image processing unit  77  calculates a difference in brightness between the image of the substrate P irradiated with the illumination light at the first inclination angle and the image of the substrate P irradiated with the illumination light at the second inclination angle, and generates a difference image (step S 12 ). The image processing unit  77  calculates a difference in luminance between the image of the substrate P irradiated with the illumination light at the first inclination angle and the image of the substrate P irradiated with the illumination light at the second inclination angle, and generates a difference image. Taking the image IM 1  and the image IM 2  as an example, differences in the regions of the cream solder SD 1  to SD 15  are relatively large, and differences in other regions are relatively small. 
     The image processing unit  77  performs binarization processing on the generated difference image to generate a binary image (step S 13 ). The image processing unit  77  performs binarization processing for each pixel in the difference image to generate a binary image of black and white. 
       FIG. 7  shows an image IM 3  obtained by performing binarization processing on the difference image. As shown in  FIG. 7 , in the image IM 3 , the regions of the cream solder SD 1  to SD 15  in which the difference in brightness is large are shown in white, and other regions including the silk M in which the difference in brightness is small are shown in black. That is, by performing the binarization processing on the difference image, regions on which the cream solder is printed are distinguished from other regions. 
     The image processing unit  77  extracts the edge of the cream solder based on the binary image (step S 14 ). The image processing unit  77  extracts edges of the cream solder SD 1  to SD 15  by extracting boundaries between the white regions and the black regions based on the image IM 3  as shown in  FIG. 7 . 
     The image processing unit  77  specifies the shape of the cream solder based on the edge of the cream solder (step S 15 ). In the example shown in  FIG. 7 , the image processing unit  77  specifies shapes of the cream solder SD 1  to SD 15 . 
     The image processing unit  77  generates, based on the specified shape of the cream solder, inspection data for inspecting the state of the cream solder printed on the substrate (step S 16 ). Specifically, the image processing unit  77  generates inspection data for determining the quality of the state of the cream solder printed on the substrate. 
       FIG. 8  shows inspection data D 1  for determining the quality of the state of the cream solder printed on the substrate. In the inspection data D 1 , the shapes of the cream solder SD 1  to SD 15  are specified in detail. The image processing unit  77  stores the generated inspection data D 1  into the storage unit  79 . The determination unit  78  compares the image of the cream solder acquired by the image acquisition unit  76  with the inspection data D 1  acquired from the storage unit  79 , and determines the quality of the state of the cream solder. 
     [Inspection Method] 
     A method for inspecting the state of the cream solder printed on the substrate according to the embodiment will be described with reference to  FIG. 9 .  FIG. 9  is a flowchart showing an example of the method for inspecting the state of the cream solder printed on the substrate according to the embodiment. 
     The image acquisition unit  76  acquires an image of the substrate on which the cream solder to be inspected is printed (step S 20 ). 
     The determination unit  78  compares the image of the substrate on which the cream solder to be inspected is printed with the inspection data stored in the storage unit  79  (step S 21 ). The determination unit  78  determines the quality of the state of the cream solder printed on the substrate based on the comparison result between the image of the substrate on which the cream solder to be inspected is printed and the inspection data stored in the storage unit  79  (step S 22 ). The determination unit  78  determines that the state of the cream solder is good when a matching rate between the shape of the cream solder to be inspected and a corresponding cream solder shape included in the inspection data is equal to or greater than a predetermined ratio. The determination unit  78  determines that the state of the cream solder is bad when the matching rate between the shape of the cream solder to be inspected and the corresponding cream solder shape included in the inspection data is less than the predetermined ratio. 
     The display control unit  80  displays the determination result of the determination unit  78  on the display device  8  (step S 23 ). 
     [Computer System] 
       FIG. 10  is a block diagram showing a computer system  1000  according to the embodiment. The control device  7  described above includes the computer system  1000 . The computer system  1000  includes a processor  1001  such as a Central Processing Unit (CPU); a main memory  1002  including a non-volatile memory such as a Read Only Memory (ROM) and a volatile memory such as a Random Access Memory (RAM); a storage  1003 ; and an interface  1004  including an input/output circuit. Functions of the control device  7  are stored in the storage  1003  as a program. The processor  1001  reads the program from the storage  1003 , expands the program into the main memory  1002 , and executes the above-described processing according to the program. The program may be distributed to the computer system  1000  via the network. 
     The program can cause the computer system  1000  to acquire images obtained by imaging, under at least two illumination conditions with different brightness, the solder normally printed on substrate P, and to extract the shape of the solder based on the difference in luminance between the acquired images so as to generate inspection data to be used for inspecting the state of the solder printed on the substrate P according to the embodiment described above. 
     As described above, the images obtained by imaging, under at least two illumination conditions with different brightness, the solder normally printed on the substrate P are acquired, the shape of the solder is specified based on the difference in brightness between the acquired images, and inspection data to be used for inspecting the state of the solder printed on the substrate is generated based on the specified shape of the solder. Thus, in the present embodiment, inspection data for determining the quality of the shape of the cream solder printed on the substrate can be automatically generated even when the design data is not available. Therefore, since the time required for the inspection process can be shortened, the work efficiency of the operator is improved. 
     Other Embodiments 
     In the above description, the illumination condition of the illumination light applied to the substrate on which the cream solder is printed during generation of the inspection data has been described as being an inclination angle of the illumination light, but the present invention is not limited thereto. The illumination condition may be, for example, brightness (light) of the illumination light. In this case, the control device  7  acquires, for example, images of a substrate on which cream solder is printed and which is irradiated under two different brightness. Then, the control device  7  specifies a shape of the solder based on a difference in brightness between the two acquired images, and generates, based on the shape of the solder, inspection data to be used for inspecting a state of the solder printed on the substrate.