JP2011038784A - Visual examination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual examination device advantageous in an aspect of the reduction of labor or cost required in visual examination. <P>SOLUTION: Chromatic aberration corrected color image data Dc2 of a printed wiring board 4 are formed where the chromatic aberration of the imaging optical system of a digital camera 18 is corrected. Inspection data D which are formed so that the chromatic aberration corrected color image data Dc2 coincide with a coordinates position are collated with the chromatic aberration corrected color image data Dc2 to perform the visual examination of the printed wiring board 4. The visual examination of the printed wiring board 4 is performed, for example, by detecting the magnitude of the positional shift of an electronic component 2 or detecting a flaw of the electronic component 2. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an appearance inspection apparatus.

An appearance inspection apparatus that inspects an inspection object such as a printed wiring board on which electronic components are mounted is used.
As such an appearance inspection apparatus, an appearance inspection apparatus has been proposed in which an entire image of a printed wiring board is imaged by an imaging apparatus, and an inspection object is inspected based on the obtained color image.
In this case, there is no need to relatively move the printed wiring board or the imaging device, which is advantageous in reducing the cost.
However, in the above-described conventional technology, since a wide range of view is required by the imaging optical system of the imaging apparatus, the angle of view of the imaging optical system is wide, so that the effect of chromatic aberration appears on the captured image, resulting in a decrease in measurement accuracy. Concerned.
For this reason, it has been proposed that a calibration work is imaged to acquire calibration data, and the image data is corrected using the calibration data (see Patent Document 1).

JP 2007-198773 A

However, the above-described prior art has a disadvantage in that it requires labor and cost for calibration.
The present invention has been made in view of such circumstances, and an object thereof is to provide an appearance inspection apparatus that is advantageous in reducing labor and cost required for appearance inspection.

  In order to achieve the above object, an appearance inspection apparatus according to the present invention has an imaging optical system, and uses the imaging optical system to image an inspection object having a plurality of alignment marks serving as reference points for coordinate positions. And imaging means for generating color image data of the inspection object, and first, second, and third image data obtained by decomposing the color image data of the inspection object into components of three primary colors of red, green, and blue Image data conversion means for converting to, contour data extraction means for extracting first, second and third contour data representing the contour of the alignment mark from the first, second and third image data, respectively. Of the first, second, and third contour data, when one contour data specified in advance is used as the specific contour data, the remaining two contour data match the specific contour data. The first Combining the first, second, and third corrected image data with image data correcting means for converting the second and third image data to generate first, second, and third corrected image data The image data combining means for combining the chromatic aberration corrected color image data of the inspection object in which the chromatic aberration of the imaging optical system is corrected, and the coordinate position of the alignment mark included in the chromatic aberration corrected color image data, Inspection data generation means for generating inspection data by converting the design data so that the coordinate positions of the alignment marks included in the design data of the inspection object match, the chromatic aberration corrected color image data, Appearance inspection means for inspecting the appearance of the inspection object by collating with inspection data.

Chromatic aberration correction color image data of an inspection object in which chromatic aberration of the imaging optical system is corrected is generated, and appearance inspection is performed by collating the chromatic aberration correction color image data and the generated inspection data so that the coordinate positions coincide with each other. I made it.
Therefore, it is not necessary to acquire calibration data by imaging a calibration work that has been conventionally performed, which is advantageous in reducing labor and cost required for appearance inspection.

It is a block diagram which shows the structure of the external appearance inspection apparatus 10 of this Embodiment. 2 is a block diagram of a computer that constitutes a control device 20. FIG. 3 is a plan view of a printed wiring board 4. FIG. It is explanatory drawing of the alignment mark 6. FIG. It is explanatory drawing of the image process by the external appearance inspection apparatus. 3 is an operation flowchart of the appearance inspection apparatus 10. It is a flowchart which shows the detail of a chromatic aberration correction process. It is explanatory drawing which shows the relationship between chromatic aberration correction color image data Dc2 and test | inspection data DB.

Next, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, a case will be described in which an object to be inspected by an appearance inspection apparatus 10 (FIG. 1) is a printed wiring board 4 on which an electronic component 2 is mounted as shown in FIG.
The printed wiring board 4 has a thin plate shape, and in the present embodiment, the printed wiring board 4 has a rectangular plate shape.
At least one surface of the printed wiring board 4 is formed as a mounting surface on which the electronic component 2 is mounted, and a plurality of alignment marks 6 are provided on the mounting surface.
The alignment mark 6 serves as a reference point for the coordinate position when the appearance inspection is performed by the appearance inspection apparatus 10.
The printed wiring board 4 includes a copper foil 4A formed on the mounting surface of the printed wiring board 4 and a resist 4B that covers the copper foil 4A.
As shown in FIG. 4, the alignment mark 6 is formed by a portion of the copper foil 4A located inside the opening 4C provided in the resist 4B covering the copper foil 4A.
In the present embodiment, the shape of the opening 4C, that is, the shape of the alignment mark 6 is a perfect circle, but various shapes such as a rectangle, a triangle, and a polygon can be used as the shape of the alignment mark 6. The shape of the mark 6 is not limited.
Here, the copper foil 4A has an orange color, and the resist 4B has a mixed color of green and blue.

Next, the appearance inspection apparatus 10 will be described.
As shown in FIG. 1, the appearance inspection apparatus 10 includes a stage 12, an illumination unit 14, a transport unit 16, a digital camera 18, and a control device 20.

  The stage 12 has a flat mounting surface 12A, and the printed wiring board 4 is mounted on the mounting surface 12A with the mounting surface facing upward.

The illumination unit 14 is supported above the stage 12 via a frame (not shown), and irradiates illumination light toward the mounting surface of the printed wiring board 4 placed on the stage 12.
The illumination unit 14 controls the color and amount of illumination light based on the control of the control means 22 (FIG. 1) described later.

The transport unit 16 transports and places the printed wiring board 4 to be inspected on the placement surface 12A of the stage 12, and places the printed wiring board 4 on which the appearance inspection has been completed on the placement surface 12A of the stage 12. It is taken out from above and transported.
The transport unit 16 is controlled in its transport operation based on the control of the control means 22 (FIG. 1) described later.

The digital camera 18 constitutes the imaging means of the present invention, and includes a housing 18A and a cylindrical lens barrel 18B protruding from the front surface of the housing 18A.
The lens barrel 18B accommodates and holds an imaging optical system that captures a subject image.
The housing 18A accommodates an image pickup device that picks up a subject image formed by the image pickup optical system, a signal processing unit that generates color image data Dc1 based on an image pickup signal generated by the image pickup device, and the like. ing.
The imaging operation of the digital camera 18 is controlled based on control of a control unit 22 (FIG. 1) described later.
In the present embodiment, the digital camera 18 is arranged with the optical axis of the imaging optical system oriented in the horizontal direction, and at the intersection of the optical axis of the imaging optical system and a vertical line passing through the mounting surface 12A of the stage 12. A reflection mirror 19 is disposed at 45 degrees with respect to the optical axis.
Therefore, the image of the printed wiring board 4 placed on the stage 12 is reflected by the reflection mirror 19 and guided to the imaging optical system. That is, the optical path connecting the printed wiring board 4 and the imaging optical system is bent 90 degrees.
With this configuration, the digital camera 18 can be disposed in the vicinity of the stage 12 while ensuring the optical path length between the printed wiring board 4 and the imaging optical system.
Therefore, it is advantageous in reducing the occupied space of the appearance inspection apparatus 10 while enlarging the area imaged by the imaging optical system.

The control device 20 is configured by a computer 100 shown in FIG.
The computer 100 includes a CPU 102, a ROM 104, a RAM 106, a hard disk device 108, a disk device 110, a keyboard 112, a mouse 114, a display 116, an input / output interface 118, and the like.
The ROM 104 stores a control program and the like, and the RAM 106 provides a working area.
The hard disk device 108 stores an appearance inspection apparatus program for causing the appearance inspection apparatus 10 to function.
The disk device 110 records and / or reproduces data on a recording medium such as a CD or a DVD.
The keyboard 112 and the mouse 114 receive operation inputs from the operator.
The display 116 displays and outputs data.
The input / output interface 118 exchanges data with the illumination unit 14, the transport unit 16, and the digital camera 18.
More specifically, the input / output interface 118 exchanges data for controlling the illumination unit 14 with the illumination unit 14.
The input / output interface 118 exchanges data for controlling the transport unit 16 with the transport unit 16.
The input / output interface 118 exchanges data for controlling the digital camera 18 with the digital camera 18 and receives color image data supplied from the digital camera 18.

As shown in FIG. 1, the control device 20 functionally includes a control unit 22, a preprocessing unit 23, an image data conversion unit 24, a contour data extraction unit 26, an image data correction unit 28, and an image The data composition means 30 is provided.
The control device 20 further includes an inspection data generation unit 32, an appearance inspection unit 34, a storage unit 36, and a display unit 38.
The control unit 22, the preprocessing unit 23, the image data conversion unit 24, the contour data extraction unit 26, the image data correction unit 28, and the image data synthesis unit 30 are realized by the CPU 102 executing the program for the appearance inspection apparatus. Is done.
The inspection data generating means 32 and the appearance inspection means 34 are realized by the CPU 102 executing the above-described appearance inspection apparatus program.
The storage means 36 includes the RAM 106, the hard disk device 108, and the recording medium loaded in the disk device 110 shown in FIG.
The storage unit 36 stores in advance imaging setting data for setting the illumination unit 14 and the digital camera 18.
The storage means 36 stores design data DA.
The design data DA includes data defining the shape of the electronic component 2 mounted on the printed wiring board 4 and the coordinate position where the electronic component 2 is to be mounted.
The design data DA includes data defining the shape and dimensions of the printed wiring board 4.
The display means 38 includes the display 116 shown in FIG.

  The control unit 22 controls the illumination unit 14, the transport unit 16, the digital camera 18, the storage unit 34, and the display unit 36.

The preprocessing unit 23 corrects lens distortion and shading in the color image data Dc1 of the printed circuit board 4.
These lens distortion correction and shading correction are performed by various conventionally known methods.

  The image data conversion unit 24 first, second, and third image data obtained by decomposing the color image data Dc1 of the printed wiring board 4 corrected by the preprocessing unit 23 into components of three primary colors of red, green, and blue. Conversion to D01, D02, D03.

  The contour data extraction unit 26 extracts first, second, and third contour data D11, D22, and D13 representing the contour of the alignment mark 6 from the first, second, and third image data D01, D02, and D03, respectively. To do.

The image data correction means 28 converts the first, second, and third image data D01, D02, and D03 to generate first, second, and third corrected image data D21, D22, and D23. .
That is, one contour data specified in advance among the contour data D11, D22, and D13 is set as the specific contour data.
Then, the image data correction unit 28 converts the image data D01, D02, and D03 so that the remaining two contour data matches the specific contour data, and generates corrected image data D21, D22, and D23. .

  The image data synthesizing unit 30 synthesizes the first, second, and third corrected image data D21, D22, and D23, thereby correcting the chromatic aberration corrected color image data of the printed wiring board 4 in which the chromatic aberration of the imaging optical system is corrected. This synthesizes Dc2.

The inspection data generation means 32 generates inspection data DB by converting the design data DA.
The design data DA is converted by the inspection data generating means 32 with respect to the coordinate position of the alignment mark 6 included in the design data DA of the printed wiring board 4 with respect to the coordinate position of the alignment mark 6 included in the chromatic aberration corrected color image data Dc2. Are made to match.

  The appearance inspection means 34 performs an appearance inspection of the printed wiring board 4 by collating the chromatic aberration corrected color image data Dc2 with the inspection data DB.

Next, the operation of the appearance inspection apparatus 10 will be described with reference to the flowchart of FIG.
The control means 22 reads imaging setting data stored in advance in the storage means 34 (step ST1).
Then, the control unit 22 sets the illumination unit 14 and the digital camera 18 based on the imaging setting data (step ST2).
Specifically, the control unit 22 sets the color and light amount of the illumination light of the illumination unit 14, and sets the aperture and shutter speed of the digital camera 18.

Next, the control unit 22 controls the transport unit 16 to transport the printed wiring board 4 to be visually inspected and place it on the placement surface 2A of the stage 2 (step ST3).
At this time, the printed wiring board 4 is positioned on the placement surface 2A using a conventionally known positioning mechanism.

Next, the control means 22 controls the digital camera 18 to image the entire mounting surface of one printed wiring board 4 (step ST4).
Thereby, the color image data Dc1 of the entire mounting surface of one printed wiring board 4 is supplied from the digital camera 18 to the control device 20 (step ST5).

The preprocessing unit 23 corrects lens distortion and shading in the color image data Dc1 of the printed wiring board 4 (steps ST6, PR1, and PR2).
If there is no need to correct lens distortion and shading, the correction processing by the preprocessing unit 23 may be omitted.
The control means 20 reads the design data DA from the storage means 36 (step ST7).

Next, a captured image chromatic aberration correction process is executed (step ST8).
The captured image chromatic aberration correction processing will be described in detail with reference to FIGS. 5 and 7.
The color image data Dc1 of the printed wiring board 4 is affected by the chromatic aberration of the imaging optical system.
That is, the contour of the image displayed by the color image data Dc1 is displayed at different positions and sizes depending on the wavelength of light, so that the contour of the image is blurred.
Specifically, the outline of the alignment mark 6 displayed by the color image data Dc1 is blurred due to the influence of chromatic aberration, as shown in FIG. It will be.

The image data conversion unit 24 first, second, and third image data obtained by decomposing the color image data Dc1 of the printed wiring board 4 corrected by the preprocessing unit 23 into components of three primary colors of red, green, and blue. Conversion to D01, D02, and D03 (step ST20).
The process of step ST20 is shown in FIGS. 5 (A), (B1), (B2), and (B3).
In this case, the first, second, and third image data D01, D02, and D03 are shown in gray gradation.
In the present embodiment, as described above, the copper foil 4A has an orange color, and the resist 4B has a mixed color of green and blue.
Accordingly, among the first, second, and third image data D01, D02, and D03, the first image data D01 in which the red component is indicated by gray gradation has the highest contrast of the image of the alignment mark 6. .
On the other hand, the second image data D02 in which the green component is indicated by a gray gradation and the third image data D03 in which the blue component is indicated by a gray gradation have a contrast higher than that of the first image data D01. It will be lowered.
As a result, of the first, second, and third image data D01, D02, and D03, the first image data D01 has the sharpest outline of the image of the alignment mark 6, and the second and third image data. In D02 and D03, the contour of the image of the alignment mark 6 is slightly blurred.

Next, the contour data extracting means 26 obtains first, second, and third contour data D11, D12, and D13 representing the contour of the alignment mark 6 from the first, second, and third image data D01, D02, and D03. Each is extracted (step ST22).
The process of step ST22 is shown in FIGS. 5 (A), (B1) to (B3).

The image data correction unit 28 converts the first, second, and third image data D01, D02, and D03 to generate first, second, and third corrected image data D21, D22, and D23 (step ST24). ).
That is, one contour data specified in advance among the first, second, and third contour data D11, D12, and D13 is set as the specific contour data.
In the present embodiment, the first contour data D11 extracted from the first image data D01 having the sharpest contour of the image of the alignment mark 6 is set as the specific contour data D11.
Therefore, the specific contour data D11 is the clearest.
As shown in FIG. 5F, when these three contour data D11, D22, and D13 are superimposed, the three contour data D11, D22, and D13 are displaced from each other and have different sizes due to the chromatic aberration described above. Become.
Therefore, the image data correction unit 28 converts the image data D01, D02, and D03 so that the remaining two contour data D12 and D13 match the specific contour data D11 as shown in FIG. To do. Accordingly, as shown in FIGS. 5C1 to 5C3, the corrected image data D21, D22, and D23 are generated.
The corrected image data D21, D22, and D23 are generated by the image data correcting unit 28 by converting the image data D01, D02, and D03 by using either or both of affine transformation and projection transformation. Note that the projection transformation is also expressed as a projective transformation or a projective transformation.

  The image data synthesizing unit 30 synthesizes the first, second, and third corrected image data D21, D22, and D23 to thereby correct the chromatic aberration of the printed wiring board 4 in which the chromatic aberration is corrected as shown in FIG. The corrected color image data Dc2 is synthesized (step ST26).

As shown in FIG. 6, the inspection data generation means 32 generates inspection data DB by converting the design data DA (step ST9).
The design data DA is converted by the inspection data generation means 32 as follows.
That is, as shown in FIG. 8, the coordinate position P1 of the alignment mark 6 included in the design data DA of the printed wiring board 4 matches the coordinate position P0 of the alignment mark 6 included in the chromatic aberration corrected color image data Dc2. To be done.
The inspection data DB is generated by the inspection data generation means 32 by converting the design data DA by using either or both of affine transformation and projection transformation.
In other words, the design data DA is deformed to create an inspection data DB as an inspection mask.
In FIG. 8, a frame 8 indicated by a two-dot chain line represents the inspection data DB, and the frame 8 defines the shape of each electronic component 2 and the coordinate position where the electronic component 2 is to be mounted.

Next, the appearance inspection means 34 collates the coordinate position of the chromatic aberration corrected color image data Dc2 with the coordinate position of the inspection data DB (step ST10), and determines whether or not the collation results match (step ST10). ST11).
In this case, the coordinate position to be collated is, for example, the coordinate position of an index (mark) at a predetermined location on the mounting surface of the printed wiring board 4.
If step ST11 is negative, 1 is added to the retry counter, and it is determined whether or not the count value N of the retry counter exceeds the reference value a (step ST16). If the determination result is negative, retry is performed.
That is, it is determined that the posture or position of the printed wiring board 4 currently being inspected is deviated from the position to be positioned for some reason, and the process returns to step ST3 and the operations of transporting and placing on the stage 12 are performed again.
If step ST16 is affirmative, it is assumed that there is an abnormality in the printed wiring board 4, the alarm means is displayed on the display means 36, and the worker is notified (step ST17). As a cause of the occurrence of such an abnormality, for example, a printed wiring board different from the printed wiring board 4 to be inspected is erroneously placed on the stage 12.
Next, the process proceeds to step ST15 described later, and data indicating the occurrence of an abnormality is stored in the storage unit 34.

If step ST11 is positive, the appearance inspection means 34 performs an appearance inspection of the printed wiring board 4 by comparing the chromatic aberration corrected color image data Dc2 with the inspection data DB (step ST12).
For example, as shown in FIG. 8, the appearance inspection unit 34 detects the size of the positional deviation of the electronic component 2 with respect to the frame line 8, and detects a missing item if there is no electronic component 2 on the frame line 8.
In other words, based on the image shift between the electronic component 2 and the frame line 8 or the mismatch between the frame line 8 and the electronic component 2, the size of the position shift of the electronic component 2 is detected, and the missing item is detected. .
Various known inspections can be employed as the appearance inspection of the printed wiring board 4.

Next, the appearance inspection unit 34 calculates a determination value from the numerical value indicating the positional deviation or missing part of the electronic component 2 detected in step ST12 (step ST13).
Then, the determination value is compared with a reference value to perform a pass / fail determination (step ST14).
If step ST14 is affirmative, data including the numerical value detected in step ST12 and the determination value calculated in step ST13 is totaled and stored in the storage means 34 (step ST15).
If step ST14 is negative, an alarm is displayed in step ST17, and then the process proceeds to step ST15.

According to the present embodiment, the chromatic aberration corrected color image data Dc2 of the printed wiring board 4 in which the chromatic aberration of the imaging optical system is corrected is generated, and the inspection generated so that the coordinate position coincides with the chromatic aberration corrected color image data Dc2. The appearance inspection is performed by collating the business data DB.
This eliminates the need for conventional calibration, which is advantageous in reducing labor and cost required for appearance inspection.

  In the present embodiment, the case where the inspection object is a printed wiring board has been described. However, it goes without saying that the present invention can be applied even if the inspection object is other than the printed wiring board.

  4 ... printed circuit board (inspected object), 6 ... alignment mark, 10 ... appearance inspection device, 18 ... digital camera (imaging means), 24 ... image data converting means, 26 ... contour data extracting means 28... Image data correcting means 30... Image data synthesizing means 32... Inspection data generating means 34.

Claims (7)

An imaging unit that has an imaging optical system, and generates color image data of the inspection object by imaging the inspection object having a plurality of alignment marks serving as reference points of coordinate positions using the imaging optical system;
Image data conversion means for converting the color image data of the object to be inspected into first, second, and third image data separated into red, green, and blue primary color components;
Contour data extracting means for extracting first, second, and third contour data representing the contour of the alignment mark from the first, second, and third image data;
Of the first, second, and third contour data, when one contour data specified in advance is used as the specific contour data, the remaining two contour data match the specific contour data. Image data correction means for converting the first, second and third image data to generate first, second and third corrected image data;
Image data synthesizing means for synthesizing the chromatic aberration corrected color image data of the inspection object in which chromatic aberration of the imaging optical system is corrected by synthesizing the first, second and third corrected image data;
Inspection data by converting the design data so that the coordinate position of the alignment mark included in the design data of the inspection object matches the coordinate position of the alignment mark included in the chromatic aberration corrected color image data Inspection data generation means for generating
Appearance inspection means for performing an appearance inspection of the inspection object by comparing the chromatic aberration correction color image data and the inspection data;
Appearance inspection device. The first, second, and third image data are indicated by gray gradations.
The appearance inspection apparatus according to claim 1. The generation of the first, second, and third corrected image data by the image data correcting means is performed by converting the first, second, and third image data by using either or both of affine transformation and projection transformation. Made by
The appearance inspection apparatus according to claim 1. The generation of the inspection data by the inspection data generation means is performed by converting the design data using both or one of affine transformation and projection transformation.
The appearance inspection apparatus according to claim 1. The inspection object is a printed wiring board on which electronic components are mounted,
The design data includes data defining the shape of the electronic component mounted on the printed wiring board and the coordinate position where the electronic component is to be mounted.
The appearance inspection apparatus according to claim 1. The inspection object is a printed wiring board on which electronic components are mounted,
The printed wiring board includes a copper foil formed on a mounting surface of the printed wiring board, and a resist covering the copper foil,
The alignment mark is formed by a portion of the copper foil located inside an opening provided in the resist covering the copper foil.
The appearance inspection apparatus according to claim 1. The inspection object is a printed wiring board on which electronic components are mounted,
The appearance inspection of the inspection object by the appearance inspection means is performed by detecting a shift in the mounting position of the electronic component or by detecting the presence or absence of a missing part of the electronic component.
The appearance inspection apparatus according to claim 1.

Images