JP4296928B2 - Solder inspection apparatus and solder inspection method - Google Patents

Description

  The present invention relates to a solder inspection apparatus and a solder inspection method for performing a predetermined inspection based on a color image obtained by imaging a substrate after solder printing.

A method using color image processing is known as a solder inspection method performed on a substrate after solder is printed. In this inspection method, a color image obtained by imaging an inspection object is subjected to image processing to separate and detect the inspection object portion on which the solder is printed. This separation / detection is performed by selecting a specific color from the color image. This is performed by extracting (see Patent Document 1, for example).
JP-A-6-27031

  When extracting a specific color from a color image, RGB image data acquired by three elements of R (red), G (green), and B (blue) is converted into H (color) and S (color). , I (brightness) is subjected to color extraction processing for extracting a specific color to be inspected from an HSI image obtained by color model conversion into three elements. However, color extraction characteristics on a substrate to be inspected are not necessarily uniform, and color extraction suitable for appearance inspection may not be performed depending on the portion.

For this reason, an inspection apparatus that performs such color model conversion changes the conversion characteristics of the data conversion table used for generating a color extraction image for any one of H, S, and I in color extraction processing, and is more appropriate. A simple color extraction image is obtained. The selection of the data conversion table is performed in the form of a color extraction teaching operation for setting color extraction parameters corresponding to desired conversion characteristics while comparing the original image and the color extraction image on the operation screen of the solder inspection apparatus. .

  However, in order to properly execute this color extraction teach, it is necessary to fully understand the effect of changing the color extraction parameters on the color extraction image. There was no method other than repeating the above, and it took a great deal of effort to obtain an appropriate result. When the inspection is performed without obtaining an appropriate color extraction image, the inspection results vary.

  Accordingly, an object of the present invention is to provide a solder inspection apparatus and a solder inspection method capable of appropriately and efficiently performing color extraction in color image processing.

The solder inspection apparatus of the present invention is a solder inspection apparatus that images a board after solder printing and performs a predetermined inspection. The board is imaged and R (red), G (green), and B (blue) 3 A camera that acquires three-dimensional RGB image data in which each element of each element is one independent dimension, and the three-dimensional RGB image data are H (color), S (color), and I (brightness). A color model conversion unit that converts each of the three elements into three-dimensional HSI image data having one independent dimension, an image extraction unit that generates a color extraction image from the HSI image data, and the color extraction image A color extraction parameter indicating a conversion characteristic of a data conversion table used for generating the color extraction image for at least one of the three elements H, S, and I; Parameter value of Image display for displaying the a parameter changing unit that changes a plurality of different parameter values change pattern, a plurality of color extraction images extracted by the data conversion table of the conversion characteristics corresponding to a plurality of different parameter values the changed simultaneously And a parameter storage unit for storing, as the inspection execution parameter value, a parameter value that gives an appropriate color extraction image selected by visually observing the plurality of color extraction images displayed simultaneously .

The solder inspection method of the present invention is a solder inspection method for imaging a substrate after solder printing and performing a predetermined inspection. The substrate is imaged and R (red), G (green), B (blue) 3 An image acquisition step of acquiring three-dimensional RGB image data in which each element of each element is an independent dimension, and the three-dimensional RGB image data are converted into H (color), S (color), and I (brightness). ), A color model conversion step of converting each of the three elements into three-dimensional HSI image data having one independent dimension, an image extraction step of generating a color extraction image from the HSI image data, and the color extraction Data used for generating the color extraction image for at least one of the three elements H, S, and I in the image extraction step. Conversion table conversion A plurality of color extractions that are extracted by a data conversion table of conversion characteristics corresponding to the changed plurality of different parameter values by changing the parameter value of the color extraction parameter indicating the property to a plurality of different parameter values in a predetermined change pattern A step of generating an image; a step of simultaneously displaying the generated plurality of color extraction images on the image display means; and a step of selecting an appropriate color extraction image by visually observing the plurality of color extraction images displayed simultaneously. And a step of setting a parameter value that gives the appropriate color extraction image as an inspection execution parameter value.

According to the present invention, in the image extraction step, the parameter value of the color extraction parameter indicating the conversion characteristic of the data conversion table used for generating the color extraction image is set for at least one of the three elements H, S, and I. Change to a plurality of different parameter values with a predetermined change pattern, simultaneously display a plurality of color extraction images extracted by the data conversion table of the conversion characteristics corresponding to the changed plurality of different parameter values on the image display means, A color value in color image processing is appropriately and efficiently performed by using, as an inspection parameter, a parameter value that gives an appropriate color extraction image selected by visually observing a plurality of color extraction images displayed simultaneously. be able to.

  Next, embodiments of the present invention will be described with reference to the drawings. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a diagram for explaining the operation of the screen printing apparatus according to the embodiment of the present invention. FIG. 5 is a plan view of the substrate printing surface of the screen printing apparatus according to the embodiment of the present invention. The block diagram which shows the structure of the control system of the solder inspection apparatus incorporated in the screen printing apparatus of one embodiment of FIG. 7, FIG. 7 is a figure which shows the color extraction teach screen of the solder inspection apparatus of one embodiment of this invention, FIG. 8 is an explanatory diagram of a parameter changing operation in the color extraction teach of the solder inspection apparatus according to one embodiment of the present invention, and the next 9 is a flowchart of color extraction parameter setting processing in the solder inspection method according to one embodiment of the present invention. 10, Figure 11 It is a diagram showing a color extraction image in the solder inspection method of an embodiment of the invention.

  First, the structure of the screen printing apparatus will be described with reference to FIG. 1, FIG. 2, and FIG. This screen printing device functions not only as a printing mechanism that prints cream solder on a substrate on which electronic components are mounted, but also as a solder inspection device that inspects the printed state of cream solder on the substrate after screen printing, as will be described later. In addition, in this solder inspection, it has a parameter setting function for setting a color extraction parameter when acquiring a color extraction image for inspection from a color image obtained by imaging a board.

1 and 2, the substrate positioning unit 1 includes a θ-axis table 4 stacked on a moving table composed of a Y-axis table 2 and an X-axis table 3, and a Z-axis table 5 disposed thereon. The substrate holder 6 is provided on the Z-axis table 5 to hold the substrate 8 sandwiched by the clamper 7 from below. The substrate 8 to be printed is carried into the substrate positioning unit 1 by the carry-in conveyor 14 shown in FIGS. By driving the substrate positioning unit 1, the substrate 8 moves in the XY directions and is positioned at a printing position and a substrate recognition position described later. The printed substrate 8 is carried out by the carry-out conveyor 15.

  A screen mask 10 is disposed above the substrate positioning unit 1, and the screen mask 10 is configured by attaching a mask plate 12 to a holder 11. The substrate 8 is aligned with the mask plate 12 by the substrate positioning unit 1 and abuts from below. As shown in FIG. 5A, electrodes 8a, 8b, 8c, and 8d for joining different types of electronic components are provided on the circuit forming surface of the substrate 8.

  On the screen mask 10, a squeegee head 13 is disposed so as to be able to reciprocate in the horizontal direction. The printing operation by the squeegee head 13 is performed in a state where the substrate positioning unit 1 holding the substrate 8 is moved to a printing position below the screen mask 10 as shown in FIG. In the printing operation, first, the substrate 8 is brought into contact with the lower surface of the mask plate 12, the cream solder 9 is supplied onto the mask plate 12, and the squeegee 13a of the squeegee head 13 is brought into contact with the surface of the mask plate 12 to slide. As a result, the cream solder 9 is printed on the printing surface of the substrate 8 through the pattern holes 16 provided in the mask plate 12. As a result, as shown in FIG. 5B, solder printing portions s1, s2, s3, and s4 are formed on the electrodes 8a, 8b, 8c, and 8d, respectively.

  Above the screen mask 10, a camera 20 that is an imaging means is provided. As shown in FIG. 3, the camera 20 is horizontally moved in the XY directions by the X-axis table 21 and the Y-axis table 22. The X-axis table 21 and the Y-axis table 22 are camera moving means for moving the camera 20.

  As shown in FIG. 2, the substrate positioning unit 1 can move the substrate 8 held by moving in the Y direction from below the screen mask 10 to the substrate recognition position by the Y-axis table 3. In this state, as shown in FIG. 4B, the camera 20 can image an arbitrary position of the substrate 8 by moving the camera 20 above the substrate 8 held by the substrate positioning unit 1. The solder inspection for the printed circuit board 8 is executed based on a color image obtained by imaging the printed circuit board 8 with the camera 20.

  Next, the configuration of the control system of the solder inspection apparatus incorporated in the screen printing apparatus will be described with reference to FIG. The control unit 23 is an overall control device, and performs overall control of each unit described below. The inspection coordinate position storage unit 24 stores the position coordinates of the parts to be subjected to solder inspection on the circuit forming surface of the substrate 8, that is, the electrodes 8a, 8b, 8c, and 8d.

  The camera 20 images the substrate 8 and extracts three elements R (red), G (green), and B (blue) from the image data, and three-dimensional RGB image data in which each element is one independent dimension. Is obtained and output. The color model conversion unit 30 converts the three-dimensional RGB image data acquired by the camera 20 into three independent elements of H (hue), S (color), and I (brightness) as one independent dimension. To three-dimensional HSI image data.

  The image extraction unit 31 acquires a color extraction image from the color model converted HSI image data. That is, an image capable of separating and extracting the solder printing portions s1, s2, s3, and s4 is acquired from the HSI image data obtained by imaging the board 8 after the solder printing. The inspection processing unit 29 performs a predetermined inspection based on the color extraction image obtained by separating and extracting the solder printing units s1, s2, s3, and s4. That is, inspection quantities indicating the positions and areas of the separated solder printing portions s1, s2, s3, and s4 are detected, and these inspection quantities are compared with a threshold value as a determination criterion to determine pass / fail. Do.

  The parameter changing unit 25 is a parameter value of a color extraction parameter indicating a conversion characteristic of a data conversion table used for generating a color extraction image for at least one of the three elements H, S, and I constituting the HSI image data. Are changed to a plurality of different parameter values in a predetermined change pattern.

  Here, the color extraction parameter will be described. When the color extraction image is generated from the HSI image data, the color extraction characteristic is such that the detection target part is extracted as a color clearly different from the surrounding colors so that the detection target part is clearly identified from the surroundings. Must be set. The color extraction characteristics are set by selecting the most suitable data conversion table from a plurality of data conversion tables created and stored in advance. As a type of the data conversion table, generally, a filter type filter is used in which data values in specific bands of H, S, and I are discarded or data values are converted by a predetermined conversion pattern.

  The color extraction parameters described above are obtained by making the conversion characteristics based on the data conversion table correspond to specific values of H, S, and I (for example, upper and lower limit values and median values of the data acquisition band in the filter format). By designating, a data conversion table having conversion characteristics corresponding to the specified parameter value is automatically selected. That is, when the parameter value of the color extraction parameter is changed step by step, the conversion characteristics of the data conversion table also change stepwise, and accordingly, the color extraction image generated from the HSI image data is stepped with a certain tendency. Change.

  In this embodiment, two elements H and I are subject to parameter change, and a color extraction image is obtained for two elements H and I by performing a predetermined operation on an execution screen for color extraction teach processing described later. The conversion characteristics of the data conversion table used for generating the data, that is, the color extraction characteristics can be set as a combination of two parameter values of the color extraction parameters corresponding to H and I, respectively.

  Here, as a parameter change pattern, the specified parameter value is set as the median value as described later, and the swing width specified in the increase / decrease direction around this median value (within the change range of all the changed parameter values). A change pattern is used in which two parameter values separated by (corresponding) are newly added to form a plurality of different parameter values.

The multiple image display setting unit 27 performs a setting process for simultaneously displaying a plurality of color extraction images extracted by a plurality of different color extraction parameters on the image display unit 32. The multiple image display setting unit 27, the image display unit 32, and the monitor 33 serve as image display means for simultaneously displaying a plurality of color extraction images extracted by a plurality of changed different color extraction parameters.

The parameter storage unit 25 selects a color extraction parameter that gives an appropriate color extraction image, that is, a color extraction parameter selected by visually observing a plurality of color extraction images obtained by changing the color extraction parameter as described above. Stored as color extraction parameters for inspection execution. The image display unit 32 performs processing for simultaneously displaying various images on the monitor 33. Here is the operation
In addition to the guidance screen at the time of input, an operation screen at the time of color extraction teaching, which will be described later, is displayed.

The operation / input unit 28 is an input unit such as a keyboard, a mouse, and a touch panel switch set on the screen of the monitor 33. The operation / input unit 28 inputs an operation command and various data, and a plurality of colors simultaneously displayed on the monitor 33. An instruction is input for selecting an appropriate color extraction image by visually observing the extraction image.

Next, color extraction teach processing executed prior to solder inspection will be described with reference to the color extraction teach screen shown in FIG. In this color extraction teaching process, a plurality of color extraction images obtained by changing the color extraction parameters described above are simultaneously displayed on the monitor screen, and the plurality of color extraction images are visually observed and an aptitude extraction image is selected. Thus, an appropriate color extraction parameter is set.

In FIG. 7, an original image display frame 37 and a color extraction image display frame 36 are set on the display screen 35. In the original image display frame 37, an original image captured by the camera 20, that is, an RGB image of the examination target part is displayed. In the color extraction image display frame 36, sub display frames 36a are set in a matrix arrangement of 3 rows and 3 columns, and each sub display frame 36a corresponds to a combination of H and I set values as color extraction parameters. The extracted color images are displayed simultaneously (see FIGS. 10 and 11).

  That is, as will be described later, in this color extraction teach, three parameter values (H1, H2, H3) and (I1, I2, I3) are set in one combination for H and I, respectively. Then, nine types of color extraction images are obtained according to nine types of combinations ((H1, I1), (H1, I2), (H1, I3)...) Obtained by combining these three types of H and I, respectively. The sub-display frames 36a are generated and displayed in an array corresponding to changes in H and I. Here, H corresponds to the row direction and I corresponds to the column direction. The central sub display frame 36a * located at the center of the color extraction image display frame 36 is a reference color extraction image corresponding to the median value (H2, I2) of the color extraction parameters that give the color extraction image.

In the color extraction teaching process, the color extraction image is displayed on the screen by operating the color extraction button 38, and a plurality of color extraction images displayed simultaneously in the color extraction image display frame 36 are visually observed, and the optimum one is selected. By touching the sub display frame 36a on which the determined image is displayed, the image is specified as a candidate image. Then, by operating the confirm button 39, the candidate image is confirmed as an inspection color extraction parameter used for actual inspection.

  The display screen 35 is provided with an H setting operation unit 40 and an I setting operation unit 41 for setting H and I parameter values as color extraction parameters. The H setting operation unit 40 includes an H band display 40a, an H median value setting button 40b, and an H amplitude setting button 40c. The I setting operation unit 41 includes an I band display 41a, an I median setting button 41b, It consists of an I swing width setting button 41c.

  With reference to FIG. 8, functions of the H setting operation unit 40 and the I setting operation unit 41 will be described. FIG. 8A shows an H band display 40a, in which three parameter values H1, H2, and H3 set at equal intervals are displayed. By operating the H median value setting button 40b, as shown in FIG. 8B, the median value M can be moved from M1 to M2 which can be arbitrarily set, and from M2 to M1. Further, by operating the H swing width setting button 40c, the overall swing width can be increased or decreased from B1 to B2 which can be arbitrarily set, and from B2 to B1.

  That is, by operating the H setting operation unit 40, a combination of three parameter values H1, H2, and H3 can be set for the color extraction parameter H by the median value M and the overall swing width B. Similarly, for the I setting operation unit 41, for the color extraction parameter I, the I median value setting button 41b and the I swing width setting button 41c are operated to specify the median value M and the overall swing width B. A combination of two parameter values I1, I2, and I3 can be set.

FIG. 10 shows an example of an image displayed on the display screen 35 by setting the parameter values (H1, H2, H3) and (I1, I2, I3) of the color extraction parameters in this way. That is, an original image obtained by imaging the solder printing portion s is displayed in the original image display frame 37, and colors corresponding to combinations of H and I parameter values are displayed in each sub-image display frame 36a of the color extraction image display frame 36. Extracted images are displayed simultaneously . In the color extraction teaching, the color extraction image displayed simultaneously in each sub-image display frame 36a is compared with the original image, and the color extraction image from which the portion corresponding to the solder printing portion s is most clearly separated and extracted is selected.

Note that the solder inspection apparatus according to the present embodiment has a function of automatically re-extracting color by designating the above-described reference color extraction image on the screen. That is, by visually observing a plurality of color extraction images displayed simultaneously on the color extraction image display frame 36, touch processing is performed on the sub display frame 36a on which the image determined to be optimal is displayed. Is automatically set as the reference color extraction image and moved to the center sub-display frame 36a *.

  Then, the color extraction parameter value used for extraction of the image is newly updated to the median value H2, I2, and other parameter values H1, H3, I1, I3 are newly set based on the preset swing width B. Is done. The color extraction image generated by the combination of these new parameter values is newly displayed in the color extraction image display frame 36, and the operator again selects a color extraction image that seems to be optimal from these color extraction images. By repeating this color extraction image selection step a plurality of times, the optimal color extraction image can be easily reached.

  Next, with reference to FIG. 9, a color extraction teach process for solder inspection executed in the solder inspection method using the above-described solder inspection apparatus will be described. This color extraction teach optimizes the color extraction parameters in order to clearly separate and extract the element solder printing portion (see FIG. 4B), which is the inspection target part, from the color image acquired by the camera 20. This is done for the purpose of setting.

  First, when the color extraction teaching for solder inspection is started in (ST1), the camera 20 is moved to the inspection position. That is, the board positioning unit 1 holding the board 8 after solder printing is moved to the recognition position (see FIG. 5B), and then the camera 20 is moved to the inspection position of the board 8 (ST2). Then, the substrate 20 is imaged by the camera 20, and the original image of solder printing (solder printing part), that is, three-dimensional RGB image data in which each of the three elements R, G, and B is one independent dimension. Obtain (ST3) (image obtaining step).

  Next, the acquired three-dimensional RGB image data is converted into three-dimensional HSI image data in which each of the three elements H, S, and I is one independent dimension (ST4) (color model conversion process) ). Then, a color extraction image for recognizing the solder printing portion is generated from the converted HSI image data (image extraction step).

  In this image extraction process, the following steps are executed. First, the color extraction parameters I and H (brightness and hue) are changed to generate a plurality of color extraction images (ST5). That is, color extraction indicating the conversion characteristics of the data conversion table used for generating the color extraction image for at least one of the three elements H, S, and I (in this embodiment, two of H and I). The parameter value of the parameter is changed to a plurality of different parameter values with a predetermined change pattern, and a plurality of color extraction images extracted by the data conversion table of conversion characteristics corresponding to the changed plurality of different parameter values are generated.

The generated plurality of color extraction images are simultaneously displayed on the monitor 33 together with the original image (ST6). Next, the plurality of color extraction images displayed at the same time are visually observed to determine the presence or absence of an appropriate color extraction image (ST7). If it is determined that there is a proper color extraction image, this proper color extraction image is selected (ST8), and a color extraction parameter that gives the selected proper color extraction image is set as a color extraction parameter for inspection execution ( ST9).

FIG. 11 shows an example of an image displayed on the display screen 35 by setting the parameter values (H1, H2, H3) and (I1, I2, I3) of the color extraction parameters. That is, as in the example shown in FIG. 10, an original image obtained by imaging the solder printing portion s is displayed in the original image display frame 37, and H and I are displayed in each sub-image display frame 36 a of the color extraction image display frame 36. Color extraction images corresponding to combinations of parameter values are displayed simultaneously . In this example, the letter A printed on the substrate surface as well as the solder printing portion s is captured in the original image.

  In such a case, as the color extraction image for solder recognition, it is necessary that the solder printing part s can be simply separated and extracted from the surroundings, and the image of the letter A and the solder printing part s can be distinguished. Become. That is, in the example shown in FIG. 11, in the case of the combination of (H1, I3), the image of the letter A and the solder print portion s can be clearly identified, and the most appropriate color extraction image is given. On the other hand, in the combination of (H2, I3), (H3, I3), (H2, I2), (H3, I2), (H3, I1), etc., the solder print portion s itself can be separated and extracted from the surroundings. However, since the image of the letter A and the solder print portion s cannot be clearly identified, it is determined that the image is inappropriate as a color extraction image for solder recognition.

  In subsequent solder inspection, a color extraction parameter for execution of inspection is applied, and a predetermined inspection is performed by the inspection processing unit based on the color extraction image generated by the color extraction parameter. In other words, the solder inspection is performed by obtaining inspection quantities indicating the positional deviation and area of the solder printing portion and comparing these inspection quantities with preset threshold values.

As described above, in the solder inspection shown in the present embodiment, in the image extraction process, data used to generate a color extraction image for two of H, I, and H among three elements of H, S, and I. The parameter value of the color extraction parameter indicating the conversion characteristic of the conversion table is changed to a plurality of different parameter values with a predetermined change pattern, and extracted by the data conversion table of the conversion characteristic corresponding to the changed plurality of different parameter values. A plurality of color extraction images are displayed simultaneously . As a result, when determining the suitability of the color extraction parameters, it is possible to visually observe a plurality of color extraction images at the same time and compare them with the original image, and to set the more appropriate color extraction parameters intuitively without requiring skill. This can be done based on reasonable judgment.

  In the conventional apparatus, only one color extraction image (corresponding to the reference color extraction image in FIG. 7) is displayed for each parameter setting operation in the color extraction teach. When it is determined that the displayed color extraction image is inappropriate, only a skilled person can determine how to change the color extraction parameter to obtain a more appropriate color extraction image. In order to perform extraction teaching, a trial-and-error method for changing color extraction parameters by hand was forced.

  On the other hand, according to the present invention, a color extraction teaching operation that could only be performed by a skilled person can be easily performed by a non-experienced person, and color extraction in color image processing can be performed appropriately and efficiently. At the same time, since an appropriate color extraction image can be obtained at all times, variations in inspection results can be eliminated and stable solder inspection can be performed.

  In the present embodiment, an example is shown in which the color extraction parameter is changed for the two elements H and I out of the three elements H, S, and I. However, instead of I, S is used as the color extraction parameter. May be included.

  The solder inspection apparatus and the solder inspection method of the present invention have an effect that color extraction in color image processing can be performed appropriately and efficiently, and a color image obtained by imaging a substrate after solder printing is obtained. This is useful in the field of performing a predetermined inspection based on the above.

1 is a front view of a screen printing apparatus according to an embodiment of the present invention. The side view of the screen printing apparatus of one embodiment of this invention The top view of the screen printing apparatus of one embodiment of this invention Operation explanatory diagram of a screen printing apparatus according to an embodiment of the present invention The top view of the substrate printing surface by the screen printing apparatus of one embodiment of this invention The block diagram which shows the structure of the control system of the solder inspection apparatus incorporated in the screen printing apparatus of one embodiment of this invention The figure which shows the color extraction teach screen of the solder inspection apparatus of one embodiment of this invention Explanatory drawing of parameter change operation in the color extraction teach of the solder inspection apparatus of one embodiment of this invention The flowchart of the color extraction parameter setting process in the solder inspection method of one embodiment of this invention The figure which shows the color extraction image in the solder inspection method of one embodiment of this invention The figure which shows the color extraction image in the solder inspection method of one embodiment of this invention

Explanation of symbols

8 Substrate 9 Cream solder 20 Camera 25 Parameter change unit 26 Parameter storage unit 29 Inspection processing unit 30 Color model conversion unit 31 Image extraction unit 32 Image display unit

Claims (4)

A solder inspection apparatus for imaging a substrate after solder printing and performing a predetermined inspection,
A camera that captures a substrate and acquires three-dimensional RGB image data in which each of the three elements R (red), G (green), and B (blue) is an independent dimension;
A color model for converting the three-dimensional RGB image data into three-dimensional HSI image data in which each of the three elements H (color), S (color), and I (brightness) is an independent dimension. A conversion unit;
An image extraction unit for generating a color extraction image from the HSI image data;
An inspection processing unit that performs the predetermined inspection based on the color extraction image;
For at least one of the three elements H, S, and I, a parameter value of a color extraction parameter indicating a conversion characteristic of a data conversion table used for generating the color extraction image is set to a plurality of different parameters with a predetermined change pattern. A parameter change section to change to a value;
Image display means for simultaneously displaying a plurality of color extraction images extracted by a data conversion table of conversion characteristics corresponding to the changed plurality of different parameter values;
A solder inspection apparatus comprising: a parameter storage unit that stores parameter values that give an appropriate color extraction image selected by visually observing the plurality of color extraction images displayed simultaneously as parameter values for inspection execution .   The parameter changing unit changes the parameter value to a plurality of parameter values by designating a median value of the plurality of parameter values and an amplitude corresponding to a change range of the plurality of parameter values as a whole. 1. The solder inspection apparatus according to 1. A solder inspection method for imaging a substrate after solder printing and performing a predetermined inspection,
An image acquisition step of imaging a substrate and acquiring three-dimensional RGB image data in which each of the three elements R (red), G (green), and B (blue) is an independent dimension;
A color model for converting the three-dimensional RGB image data into three-dimensional HSI image data in which each of the three elements H (color), S (color), and I (brightness) is an independent dimension. Conversion process;
An image extraction step of generating a color extraction image from the HSI image data;
An inspection processing step for performing the predetermined inspection based on the color extraction image,
In the image extraction step, a parameter value of a color extraction parameter indicating a conversion characteristic of a data conversion table used for generating the color extraction image for at least one of the three elements H, S, and I is changed in a predetermined manner. Changing to a plurality of different parameter values in the pattern, and generating a plurality of color extraction images extracted by a data conversion table of conversion characteristics corresponding to the changed plurality of different parameter values;
Displaying the generated plurality of color extraction images simultaneously on the image display means;
Selecting an appropriate color extraction image by visually observing the plurality of color extraction images displayed simultaneously ;
And a step of setting a parameter value giving the appropriate color extraction image as an inspection execution parameter value.   4. The solder inspection method according to claim 3, wherein the parameter value is changed by designating a median value of the plurality of parameter values and a swing width corresponding to a change range of the plurality of parameter values as a whole.

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