JP2014102206A - Solder inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder inspection method capable of efficiently inspecting solder by correcting the position of a substrate in a short time.SOLUTION: The solder inspection method uses a solder inspection apparatus including: a camera (imaging means) 5 for imaging a soldered portion of an electronic component soldered on a substrate 7; an illumination device (illumination means) 6 for illuminating the soldered portion of the electronic component; an image processing device (image processing means) 2 for determining the quality of soldering through processing on the image obtained by the camera 5; and a monitor (display means) 3 for displaying the result of the determination by the image processing device 2. In the solder inspection method, plural geometric feature points are extracted from the image subjected to the image processing by the image processing device 2, and the feature points are used as reference points for correcting the position of the substrate 7.

Description

  The present invention relates to a solder inspection method for determining, by image processing, whether or not a substrate on which electronic parts are soldered is soldered.

  A plurality of terminals (lead pins) of electronic components are soldered on the substrate, and this soldering is automatically performed by a soldering apparatus. That is, in the soldering apparatus, the substrate is set on a horizontal table of the robot, the robot is driven and controlled based on the coordinates of the terminals of the electronic components stored in the controller, and the soldering iron held by the robot. Are successively moved to each terminal position. Then, the soldering iron moved to the predetermined terminal position of the electronic component is heated, and the solder supplied automatically to the soldering iron is melted to solder the terminal to the predetermined position on the substrate. Similarly, these terminals are automatically and continuously soldered onto the substrate while the soldering iron sequentially moves to the respective terminal positions.

  Thus, the quality of soldering of electronic parts in which a plurality of terminals are soldered on the board as described above (including solder bridge inspection of whether or not foreign matter such as solder exists between the terminals on the board) Are inspected by solder inspection equipment. Here, the solder inspection apparatus is for inspecting the quality of soldering by image processing, and has an imaging means for imaging the soldered portion of the electronic component soldered on the substrate, and the soldered portion of the electronic component Illuminating means for illuminating, image processing means for processing the image picked up by the image pickup means to determine the quality of soldering, and display means for displaying the determination result by the image processing means. .

  In the solder inspection by such a solder inspection apparatus, a position correction for correcting the deviation from the normal position of the substrate is performed. This position correction is performed by using a discarded region of the substrate 107 (the substrate 107 as a product as shown in FIG. 4). This is done by detecting the positions of a plurality of reference marks M (two locations on the diagonal line of the substrate 107 in the illustrated example) 107a added to the unnecessary area remaining after being divided into a plurality of each time.

  By the way, Patent Document 1 proposes a method of detecting the position of a substrate using a wiring pattern on the substrate as a reference mark.

JP-A-9-167899

  However, in the method of correcting the position of the substrate 107 by detecting the position of the reference mark M as shown in FIG. 4, the image pickup means and the illumination means are provided on the reference mark M provided outside the inspection area on the substrate 107. Since it is necessary to move to the position, there is a problem that the inspection takes time for the movement time and the inspection efficiency is deteriorated.

  Further, in the method proposed in Patent Document 1, since the wiring patterns on the substrate are diverse and the shapes thereof are complicated, the quantization error in the image processing becomes non-uniform and high-precision position correction is difficult. There is a problem that there is.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a solder inspection method capable of efficiently performing solder inspection by correcting the position of a substrate in a short time.

  In order to achieve the above object, the present invention provides an image pickup means for imaging a soldered portion of an electronic component soldered on a substrate, an illumination means for illuminating the soldered portion of the electronic component, and an image pickup by the image pickup means. As a solder inspection method using an image processing means for processing a processed image to determine the quality of soldering and a display means for displaying a determination result by the image processing means, the image processing means A plurality of geometric feature points are extracted from an image to be image-processed, and the feature points are used as reference points for correcting the position of the substrate.

  According to the present invention, since the position of the substrate is corrected using the geometric feature point in the image region to be inspected as a reference point, it is not necessary to move the imaging means and the illumination means for position correction, It is possible to perform the solder inspection efficiently by correcting the position of the substrate in a short time. Further, the reference mark provided outside the inspection area of the substrate becomes unnecessary, and the feature point can be used even after the substrate is divided.

It is a perspective view which shows the basic composition of the solder test | inspection apparatus used for the solder test | inspection method which concerns on this invention. (A)-(d) is explanatory drawing which shows the procedure of the solder inspection method which concerns on this invention. It is a flowchart which shows the procedure of the solder inspection method which concerns on this invention. It is a top view of the board | substrate with which the reference mark used for the conventional solder inspection method was attached | subjected.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a basic configuration of a solder inspection apparatus used in a solder inspection method according to the present invention. The illustrated solder inspection apparatus includes a robot 1 driven and controlled by a controller (not shown), and image processing means. An image processing apparatus 2 and a monitor 3 as display means.

  The robot 1 holds a soldering iron 4, a camera 5 as an imaging means, and an illuminating device 6 as an illuminating means, and these are rotated in directions of rotation about X, Y, Z axes and Z axes as orthogonal coordinate axes. A substrate 7 having a rectangular flat plate shape is set on the horizontal table 1a. A controller (not shown) for driving and controlling the robot 1 stores in advance position coordinates of terminals of electronic components mounted on the substrate 7, and the soldering iron 4 held by the robot 1 is an electronic component. Each terminal is automatically and continuously soldered onto the substrate 7 while moving to the position of each terminal.

  Thus, the solder inspection apparatus configured to include the camera 5, the illumination device 6, the image processing device 2, and the monitor 3 held by the robot 1 includes a plurality of electronic components mounted on the substrate 7. The terminal 8 (see FIG. 2) is judged whether the soldering is good or not (including a solder bridge inspection of whether or not there is a foreign substance such as solder between the terminals 8 on the substrate 7).

  Here, the illumination device 6 is for illuminating the inspection area by irradiating light onto the inspection area including the soldered portions of the plurality of terminals 8 of the electronic component mounted on the substrate 7, and the camera Reference numeral 5 denotes an image of an inspection area illuminated by the illumination device 6. The image processing apparatus 2 processes an image captured by the camera 5 to determine whether the terminal 8 is soldered. The monitor 3 determines that the image is processed by the image processing apparatus 2. The quality of soldering performed is displayed.

  Next, a solder inspection method according to the present invention implemented using the solder inspection apparatus described above will be described in accordance with the procedure with reference to FIGS.

  FIGS. 2A to 2D are explanatory views showing the procedure of the solder inspection method according to the present invention, and FIG. 3 is a flowchart showing the procedure of the solder inspection method. The illuminated inspection region of the substrate 7 is picked up by the camera 5 and the image data is input to the image processing device 2 (step S1 in FIG. 3), and the image (camera image) shown in FIG. Is displayed. In FIG. 2, reference numeral 8 denotes a plurality of terminals of an electronic component (not shown) mounted on the substrate 7. These terminals 8 penetrate the substrate 7 and protrude from the surface of the substrate 7. Are respectively soldered to the substrate 7 by solder 9. Reference numeral 10 denotes a wiring pattern disposed on the substrate 7, and this wiring pattern 10 is formed on a wiring pattern (not shown) disposed on the back surface of the substrate 7 through circular conductive portions 11, 12, 13. Electrically connected.

  When the image data of the inspection area of the substrate 7 is input to the image processing device 2 as described above, the image processing device 2 differentiates the image data to obtain a line drawing (a diagram showing a boundary line) ( Step S2), a portion having a strong edge in the image is selected by determining the threshold value (Step S3). Then, a portion closed by a line in the image is extracted by area detection (step S4), and the area of the portion is calculated (step S5).

  The area obtained by the area calculation is compared with a predetermined threshold value, and it is determined whether there are 10 or more locations where the area exceeds the threshold value (step S6). If the area where the area exceeds the threshold is less than 10 points, the threshold value is changed, and the processing of steps S2 to S6 is repeated until the area where the area exceeds the threshold reaches 10 points or more. If there are 10 or more points, a candidate point of a feature point having a geometric feature in the image is selected (step S7).

  In the present embodiment, the circular hole-like conductive portions 11 to 13 of the wiring pattern 10 existing in the inspection region of the substrate 7 are selected as feature points, and the circularity of the feature points is calculated (step S8). In the present embodiment, the circularity of the perfect circle is set to 1.0, and the circularity value is defined to be smaller as the shape is further away from the perfect circle.

  When the circularity of a point that is a candidate for a feature point is calculated as described above, it is determined whether the calculated circularity is equal to or greater than a threshold value (0.8 in the present embodiment) (step). S9) If there is a point having a circularity of a threshold value (= 0.8) or more, that point is selected as a feature point (step S10). Next, the number of selected feature points is determined (step S11). If the number is 3 or more, the feature points are registered as reference points (step S12), and the board is based on the reference points. 7 is detected, the amount of deviation from the regular position of the substrate 7 is obtained, the position of the substrate 7 is corrected so that the amount of deviation is zero, and the substrate 7 is reset to the regular position. In the present embodiment, the three conducting portions 11 to 13 shown in FIG. 2B are selected as feature points.

  By the way, when there is no point having a circularity of a threshold value (= 0.8) or more, or when the number of selected feature points is less than 3, the processes of steps S6 to S11 are repeated.

  Thus, when the substrate 7 is set at the proper position, the image processing apparatus 2 is inspected between the adjacent solders 9 as shown in FIG. 2C (with a rectangular frame in FIG. 2C). 2), the quality of soldering of each inspection location is determined based on the luminance information of each inspection location, and the result is displayed on the monitor 3 as shown in FIG. Here, when an image of an unnecessary solder 14 is present at an inspection location indicated by a broken line (actually displayed in red) in FIG. 2D, the determination result of the inspection location is NG. The determination result of the inspection location indicated by the solid line (actually blue display) is OK.

  As described above, according to the solder inspection method of the present invention, the position of the substrate 7 is corrected using the conduction portions 11 to 13 which are geometric feature points in the image region to be inspected as the reference point. Thus, it is not necessary to drive the robot 1 to move the camera 5 or the illumination device 6 for position correction, and it is possible to perform solder inspection efficiently by correcting the position of the substrate 7 in a short time. .

  Further, the solder inspection method according to the present invention eliminates the need for a reference mark that has conventionally been provided outside the inspection region of the substrate 7, and also provides the advantage that the feature points can be used even after the substrate 7 is divided. .

DESCRIPTION OF SYMBOLS 1 Robot 1a Robot table 2 Image processing apparatus (image processing means)
3 Monitor (display means)
4 Soldering iron 5 Camera (imaging means)
6 Lighting equipment (lighting means)
7 Substrate 8 Terminal 9 Solder 10 Wiring pattern 11-13 Conductive part (feature point)
14 Unnecessary solder

Claims (1)

Image pick-up means for picking up the soldered portion of the electronic component soldered on the substrate, illumination means for illuminating the soldered portion of the electronic component, and the quality of soldering by processing the image picked up by the image pick-up means A solder inspection method using a solder inspection apparatus provided with an image processing means for determining and a display means for displaying a determination result by the image processing means,
A solder inspection method, wherein a plurality of geometric feature points are extracted from an image processed by the image processing means, and the feature points are used as reference points for position correction of the substrate.

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