JP2002048732A - Visual inspection device and visual inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a visual inspection device and a visual inspection method for accurately performing detection on a smooth surface with low surface roughness for improving inspection accuracy. SOLUTION: In the visual inspection, a predetermined inspection is carried out by color image processing of color image data obtained by photographing a mounted base board. In photographing an inspection object having a detection objective part with surface roughness different from that around it such as a polarity mark formed on the upper face of an electronic part 3, when a chromatic illuminating light is radiated in the coaxial direction by means of a coaxial light source part 4e while regular reflection light of the chromatic illuminating light from the polarity mark with the low surface roughness is received by means of the camera 5, the detection objective part is discriminated from the periphery. In this way, the smooth surface with low surface roughness can be precisely separated and discriminated by means of color image processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection apparatus and a visual inspection method for performing a predetermined inspection on an inspection object by performing color image processing on color image data obtained by imaging the inspection object. is there.

[0002]

2. Description of the Related Art In the field of manufacturing electronic components and equipment,
2. Description of the Related Art Appearance inspections in which an inspection object such as an electronic component or a board is imaged by a camera and a predetermined inspection is performed are widely performed. In the appearance inspection, various items such as detection and identification of an inspection target such as an electronic component and misalignment are determined by performing image processing on image data of the inspection target. Among these inspection items, color image processing using a color image is performed for an inspection item that can be determined by using a difference in color between the board and the electronic component, such as the presence or absence of an electronic component and a position shift. Done.

[0003]

However, the conventional visual inspection using a color image has the following problems. In the inspection items of the appearance inspection, a detection target portion may be a smooth surface having a small roughness compared to the surroundings, such as a polarity mark of an electronic component and a positioning mark of a substrate. Such detection targets can be easily identified from the surroundings by visual inspection, but in color appearance inspection, these detection targets are clearly separated from the surroundings on the color image by light reflected from the smooth surface and received by the camera.・ It was difficult to identify.

Accordingly, an object of the present invention is to provide a visual inspection device and a visual inspection method capable of accurately detecting a smooth surface having a small surface roughness and improving the inspection accuracy.

[0005]

According to a first aspect of the present invention, there is provided a visual inspection apparatus for performing color image processing on color image data obtained by imaging an inspection object having a detection target portion having a surface roughness different from that of the surroundings. A camera for imaging the inspection object, first illumination means for irradiating the inspection object with white illumination light from all directions, and an inspection object for imaging. Second illumination means for irradiating the object with colored illumination light from the coaxial direction.

According to a second aspect of the present invention, a predetermined inspection is performed by performing color image processing on color image data obtained by imaging an inspection target having a detection target portion having a surface roughness different from that of the surroundings. An appearance inspection method, wherein when the inspection object is imaged by a camera, the inspection object is irradiated with colored illumination light from the coaxial direction, and the detection target portion and the surroundings are colored from the one with the smaller surface roughness. By detecting the specular reflected light of the illumination light by the camera, the detection target part is identified from the surroundings.

According to the present invention, when capturing an image of an inspection object having a detection target portion having a surface roughness different from that of the surroundings, the inspection target object is irradiated with colored illumination light from the coaxial direction, thereby detecting the detection target portion and the surroundings. The camera receives the specularly reflected light of colored illumination light from the one with the smaller surface roughness and identifies the detection target part from the surroundings, so that a smooth surface with small surface roughness can be accurately separated by color image processing.・ Can be identified.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a visual inspection apparatus for a mounting board according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a color extraction process according to an embodiment of the present invention, and FIG. FIG. 4 is a flowchart of an electronic component mounting state inspection process according to one embodiment of the present invention, and FIG. 5 is a flowchart of a soldering state inspection process according to one embodiment of the present invention. 6, FIG. 6 is a flowchart of a solder bridge inspection process according to an embodiment of the present invention, FIG. 7 is an explanatory diagram of a solder inspection process according to an embodiment of the present invention, and FIG. FIG. 9 is an explanatory diagram of a bridge inspection process, FIG. 9 is a flowchart of an electronic component polarity inspection process of one embodiment of the present invention, and FIG. 10 is an explanatory diagram of an electronic component polarity inspection process of one embodiment of the present invention. .

First, the configuration of a visual inspection apparatus for a mounting board will be described with reference to FIG. In FIG. 1, a mounting substrate 2 (hereinafter simply referred to as “substrate 2”), which is an inspection target on which electronic components are mounted, is held on an XY table 1. Different electronic components 3 are mounted. As shown in FIG. 3, a recognition mark 2a for position recognition is formed on the substrate 2 at a diagonal position.
On the upper surface, a circuit electrode 2b for joining electronic components is formed. Terminal type rectangular electronic components 31A and 31B are provided on the electrode 2b.
And lead-type electronic components 32, 3 having bonding leads
Many different types of electronic components such as 3 are soldered.

In the appearance inspection, the polarity of the presence / absence and displacement of the electronic component and the direction of the electronic component is determined.
The quality of a soldering state for joining the electronic component to the circuit electrode is inspected optically. That is, the recognition mark 2a
, The position of the substrate 2 is detected, and the position of each electronic component is specified based on this position. In the polarity inspection, the polarity mark 3 formed on the upper surface of the electronic component 33 is used.
By recognizing 3a, the polarity of the electronic component 33 is determined. The soldering state is inspected by imaging the periphery of the lead 33b and recognizing the size and shape of the solder fillet.

Above the substrate 2, an image pickup unit including a lighting unit 4 and a camera 5 is provided. The illuminating unit 4 includes a ring-shaped illuminator 4a for emitting white light emitted by a halogen light source unit (not shown) and a substantially hemispherical reflector 4b. Is scattered and reflected by the spherical reflecting surface, and illuminates the substrate 2 below from all directions. That is, the light emitter 4a and the reflector 4b constitute an all-sky first illuminating unit that emits white illumination light.

Further, inside the reflector 4b, LED light sources 4c and 4d for emitting red light are provided in upper and lower stages, and the red light emitted from the LED light sources 4c and 4d is provided in the lower part. The substrate 2 is irradiated from different oblique directions. That is, the LED light sources 4c, 4d
Is a multi-stage second illumination means for irradiating the substrate 2 with illumination light from a plurality of specific directions having different directions.

Further, the illumination section 4 has a coaxial light source section 4e disposed above the reflector 4b. The coaxial light source unit 4e emits light by an LED, and the irradiation light from the coaxial light source unit 4e is applied to the half mirror 4 provided in the opening of the reflector 4b.
The light is reflected by f and enters the lower substrate 2 from the coaxial direction of the camera 5.

The illumination unit 4 is connected to an illumination control unit 18. The illumination control unit 18 controls the illumination unit 4 to emit white illumination light for all-sky illumination.
a, LED light source unit 4 that emits red light for multistage illumination
Only one of c, 4d and the coaxial light source section 4e for coaxial illumination, or a combination thereof, can be turned on. Therefore, the illuminants 4a,
Alternatively, the LED light sources 4c and 4d, which are the second lighting means, can be selectively switched on and turned on. That is, the illumination control unit 18 is an illumination switching unit that switches between the first illumination unit and the second illumination unit.

A camera 5 is disposed above the illuminating section 4 in a downward direction, and the camera 5 is illuminated by the above-described various illuminating means via an opening provided above the reflector 4b. 2 is imaged. At this time, the XY table 1
, The substrate 2 moves horizontally, and an arbitrary electronic component 3 mounted on the substrate 2 can be positioned just below the camera 5 and imaged.

The camera 5 is connected to a camera control unit (CCU) 6. The camera control unit 6 controls an imaging operation of the camera 5 such as an imaging timing, and performs R (red), G
The three primary colors (green) and B (blue) are extracted and output as image data for each element. The image data of the three elements R, G, and B are stored in the first image storage unit 8 and sent to the color model conversion unit 7.

The color model conversion unit 7 converts the three-dimensional RGB image data, in which each of the three elements of R, G, and B has one independent dimension, into H (hue), S (saturation),
Each element of (brightness) as one independent dimension 3
It is converted into dimensional HSI image data. Converted HSI
The image data is stored in the second storage unit 9. The HSI image data is sent to the color extraction unit 13 and
In step 3, a process of extracting a color of a predetermined portion in the imaging field of view using the HSI image data, that is, a process of synthesizing an image in which the original color of the portion is replaced with another specific color (color extracted image) is performed. . The color extraction image obtained by the color extraction processing is stored in the third image storage unit 10.

The soldering state inspection unit 11 inspects the soldering state of the electronic component by performing image processing on the RGB image data stored in the first image storage unit 8. Therefore, the soldering state inspection unit 11 is a solder inspection unit. The component mounting state inspection unit 12 inspects the mounting state of the electronic component, that is, the presence / absence and displacement of the electronic component by performing image processing on the color extraction image stored in the third image storage unit 10 after the color extraction processing. I do. Therefore, the component mounting state inspection unit 12 is a mounting inspection unit.

The soldering state inspecting unit 11, the component mounting state inspecting unit 12, and the color extracting unit 13 are connected to an overall control unit 14. The overall control unit 14 includes an inspection data storage unit 15, a library storage unit 16, and an inspection unit. Each storage unit of the result storage unit 17 is connected. The inspection data storage unit 15 stores inspection sequence data indicating an operation order in the inspection processing of the mounting state inspection device. The inspection sequence data includes component identification information for identifying an electronic component to be inspected, a color code, and information on an inspection item.

The library storage unit 16 stores a component library including various data on electronic components to be inspected. The data of this part library is read out by the overall control unit 14 and sent to the color extraction unit 13.
Here, color extraction processing using library data corresponding to each electronic component is performed. The inspection result storage unit 17 receives and stores the inspection results of the soldering state inspection unit 11 and the component mounting state inspection unit 12 via the overall control unit 14. The lighting control unit 18 controls lighting of the lighting unit 4 and controls lighting conditions such as illuminance. The mechanism control unit 19 controls the operation of the XY table 1 for holding and positioning the substrate 2.

Here, the color extraction processing will be described with reference to FIG. An RGB image 20 of the substrate 2 including the electronic component 3 captured by the camera 5 and output by the camera control unit 6 is subjected to color model conversion into HSI image data by a color model conversion unit 7. Here, a process of converting color data expressed in RGB dimensions into data in HSI dimensions is performed for each pixel forming an image, and the data after color model conversion is converted into H, S, and I types. Each data is separated and output.

Thus, the second image storage unit 9 stores an image in which the data of each of H, S, and I correspond to each pixel, that is, the color conversion image 9 represented only by H (hue).
a, color-converted images 9b and I expressed only by S (saturation)
A color conversion image 9c represented only by (lightness) is stored.
Then, these image data are sent to the color extracting unit 13,
A conversion table 21 for each of the H, I, and S image data
(H table 21a, S table 21b, I table 2
Data conversion using 1c) is performed.

In the data conversion using the conversion table 21, the numerical data of H, S, I obtained for each pixel are converted into new numerical data H ', S', according to a predetermined conversion rule.
This is done by replacing it with I '. The conversion table 21 used here determines this conversion rule, and a conversion table having different characteristics is set according to the inspection target.

The data converted H ', S', I '
Are synthesized by the synthesis processing unit 22 to synthesize a color extracted image. The synthesized color extraction image is stored in the third image storage unit 10. By performing such a color extraction process, in the example shown in the present embodiment, the part of the electronic component 3 to be detected is in the white part 23a, and the other parts are non-white in which the color changes from black to gray. The converted color extraction image (monochrome image) 23 is obtained by the unit 23b.
The color-extracted image from which the color has been extracted is sent to the component mounting state inspection unit 1.
2, where an inspection is performed as to whether or not a predetermined electronic component is properly mounted at a predetermined position in a correct position.

This apparatus for inspecting the appearance of a mounting board is configured as described above. Next, the mounting state inspection processing will be described with reference to FIG. First, the substrate 2 to be inspected is placed on the XY table 1. Then, the white light is turned on by turning on the light emitter 4a (ST1). Next, an image including the electronic component to be inspected is captured by the camera 5 (ST2). As a result, the RGB image of the substrate 2 is output from the camera control unit 6, and the color model is converted into an HSI image by the color model conversion unit 7 (ST3).

Next, color extraction processing is performed on the color capture area set in the inspection target region by the color extraction unit 13 (ST4). Then, an inspection process is performed on the color extraction image by the component mounting state inspection unit 12 (S
T5). That is, by performing image processing on the color extraction image, the presence / absence of an electronic component on the substrate 2 and the displacement are detected.

Next, the inspection of the soldering state will be described with reference to FIGS. This soldering state inspection is performed by detecting the shape of a solder fillet that joins the lead 33b of the electronic component 33 shown in FIG.
It is to determine whether or not the soldering is performed normally. In this inspection, first, the upper illumination is turned on (ST11). That is, the LED provided in the lighting unit 4
The light source unit 4d and the coaxial light source unit 4e are turned on, and the substrate 2 is irradiated with red illumination light from above.

Then, in this state, an image of the solder fillet portion is captured (ST12). Then, as shown in FIG.
Illumination light applied to the flat surfaces of the electronic component leads 33b and the upper surface of the electrodes 2b of the substrate 2 to which the solder is not bonded is reflected upward by these horizontal surfaces and received by the camera 5. On the other hand, the illumination light incident on the inclined surface of the solder fillet 34 formed by joining the upper surface of the electrode 2b and the side surface of the lead 33b is reflected in the oblique direction, and is not received by the upper camera 5. Thereby, on the image acquired by the camera 5, a monochrome image having a clear luminance difference between the upper surface of the lead 33b or the surface of the electrode 2b and the solder fillet 34 can be obtained as shown in FIG. Then, an inspection process is performed based on this image (ST13).

That is, when the solder fillet 34 exists, a dark portion indicating the solder fillet 34 appears in the image as shown in FIG. 7A, and when the solder fillet 34 does not exist, the image shown in FIG. As shown in (b), only the bright part appears in the area between the lead 33b and the electrode 2b. By detecting the dark portion indicating the presence of the solder fillet 34 on the monochrome image, the presence or absence of the solder fillet 34 is determined, and the shape defect of the solder fillet 34 can be detected based on the detected shape and area of the dark portion. it can.

Next, the solder bridge inspection will be described with reference to FIGS. This solder bridge inspection is a problem in which, when a large number of leads 33b are arranged at a narrow pitch, as in the electronic component 33 shown in FIG. It detects the presence or absence. In this inspection, first, the lower stage illumination, that is, the LED light source unit 4c arranged in the lower stage is turned on (ST21). As a result, the surface of the substrate 2 is irradiated with red illumination light from an oblique direction at a low angle as shown in FIG. 8A, and an image between the leads is captured in this state (ST22). Then, an inspection process is performed based on the captured image (ST23).

In the reflected light of the illumination light emitted obliquely in this image capture, the reflected light obliquely reflected by a horizontal surface such as the upper surface of the lead 33b or the upper surface of the electrode 2b is not received by the camera 5. In contrast, the solder fillet 34 formed on the end face of the lead 33b and the electrode 2
Light reflected from a portion having a sloped side surface, such as a solder bridge 35 protruding from b, is received by the upper camera 5. As a result, as shown in FIG. 8B, only the portions corresponding to the inclined side surfaces of the solder fillet 34 and the solder bridge 35 are glossy portions 34a and 35a in the image.
Appears. The presence or absence of the solder bridge 35 can be determined based on whether or not the glossy portion 35a is detected.

That is, in the solder inspection for inspecting the soldering state of the electronic component, the multi-stage LED light source 4c,
By selectively lighting 4d and the coaxial light source 4e,
Illumination light is emitted from a specific direction according to the inspection target site. By receiving the reflected light from the illumination by the upper camera 5, it becomes possible to process different inspection items by the same imaging means.

Next, the polarity inspection process of the electronic component will be described with reference to FIGS. The polarity inspection detects whether the electronic component having the polarity in the mounted state (see the electronic component 33 shown in FIG. 3) is mounted in the correct direction by detecting the polarity mark 33a formed on the upper surface of the electronic component 33. It is determined by doing. This polarity mark 33
Since a is directly formed on the resin mold of the electronic component 33, it is originally of the same quality and same color. On a color image captured under white illumination, the polarity mark 33a is formed as shown in FIG. It is difficult to clearly discriminate from the surroundings.

Therefore, in this polarity inspection, first, both the coaxial illumination and the white illumination are turned on (ST31). That is, the light emitter 4a of the illumination unit 4 and the coaxial light source unit 4e are both turned on. As a result, the substrate 2 is irradiated with white illumination light from all sky directions having no direction and red illumination light from the vertical coaxial direction.

In this state, an image of the upper surface of the electronic component 33 is captured (ST32). In this image capture, in the portion of the polar mark 33a having a smooth surface with a small surface roughness, the red illumination light from the coaxial direction is highly specularly reflected upward, and the specularly reflected light is received by the camera 5. You. Thus, on the captured color image, red of the same color as the colored illumination light is detected at the portion of the polarity mark 33a. In the present embodiment, red light is used as colored illumination light emitted from the coaxial direction. However, illumination light other than red may be used as long as the color can be distinguished from the surroundings.

On the other hand, since the upper surface of the electronic component 33 other than the polar mark 33a has a large surface roughness, the red illumination light applied to this area is diffusely reflected, and the reflected light incident on the upper camera 5 is small. In a range other than the polar mark 33a, the camera 5 receives diffuse reflection light of white illumination light emitted from all directions. That is, in the portion other than the polarity mark 33a on the color image, the original color of the resin mold of the electronic component 33 is detected. Therefore, as shown in FIG. 10B, in the image of the electronic component 33, different colors are detected from the polarity mark 33a and the surrounding area, whereby the polarity mark 33a is identified from the surrounding area.

As described above, in the case where the electronic component 33 has a difference in surface roughness due to a difference in surface treatment, and a portion where the surface roughness is different from the surroundings is a detection target portion, the smaller the surface roughness is, the better. By receiving the specularly reflected light of the colored illumination light from, it is possible to identify, from the surroundings, a detection target portion having the same material and the same color, such as the polarity mark 33a. And a polar mark 33a on the upper surface of the electronic component 33.
The inspection process is performed by detecting the position of (ST3).
3) The polarity of the electronic component 4, that is, the correctness of the mounting direction is detected.

In the above-described embodiment, an example is shown in which the light emitter 4a of the illumination unit 4 and the coaxial light source unit 4e are both turned on. However, only the coaxial light source unit 4e is turned on to perform regular reflection of colored illumination light. Only the light may be received by the camera 5.
Also according to this method, the polarity mark 33a can be separated and identified from the surroundings.

In the present embodiment, the polarity mark of the electronic component has been described as an example of a detection target portion having a surface roughness different from that of the surroundings. However, other examples, for example, a recognition mark formed on the surface of the substrate 2. The present invention can also be applied to a case where the mark 2a or an electrode having a solder leveler having a solder film formed on the surface for the purpose of improving solder jointability is a detection target portion.

In the case of the recognition mark of the substrate, similarly to the case of the polarity mark, the specular reflection light from the surface of the recognition mark which is smooth and has a small surface roughness as compared with the surface of the surrounding substrate is received. The recognition mark is separated and identified from the surroundings.
Also, in the case of an electrode having a solder leveler, by receiving specularly reflected light from the electrode surface (solder film surface) having a smaller surface roughness as compared with cream solder applied to the upper surface of the electrode, the solder level is reduced. It is possible to separate and identify cream solder that is difficult to identify on a color image in a color similar to the electrode surface covered with the film from the electrode surface.

In the above embodiment, the example of the mounting board on which the electronic component is mounted as the inspection target is shown.
The present invention is not limited to this, and may be a case where a work in an individual state such as an electronic component is to be inspected.

[0042]

According to the present invention, when picking up an image of an inspection object having a detection target portion having a surface roughness different from that of the surroundings, the inspection target object is irradiated with colored illumination light from the coaxial direction to thereby detect the detection target portion. The camera receives the specularly reflected light of colored illumination light from the smaller surface roughness of the surrounding area and identifies the detection target part from the surrounding area. Can be well separated and identified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a mounting board appearance inspection apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a color extraction process according to an embodiment of the present invention;

FIG. 3 is a plan view of a mounting board according to one embodiment of the present invention;

FIG. 4 is a flowchart of an electronic component mounting state inspection process according to one embodiment of the present invention;

FIG. 5 is a flowchart of a soldering state inspection process according to one embodiment of the present invention;

FIG. 6 is a flowchart of a solder bridge inspection process according to one embodiment of the present invention;

FIG. 7 is an explanatory diagram of a solder inspection process according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of a solder bridge inspection process according to one embodiment of the present invention.

FIG. 9 is a flowchart of a polarity inspection process of an electronic component according to an embodiment of the present invention.

FIG. 10 is an explanatory diagram of a polarity inspection process for an electronic component according to an embodiment of the present invention.

[Explanation of symbols]

 2 Board 2a Recognition mark 3 Electronic component 4 Illumination unit 4a Light emitter 4b Reflector 4c, 4d LED light source unit 5 Camera 7 Color model conversion unit 11 Soldering state inspection unit 12 Component mounting state inspection unit 18 Lighting control unit 33 Electronic component 33a Polarity mark

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/00 H05K 3/00 Q F term (Reference) 2F065 AA03 AA49 AA50 AA53 BB27 CC25 CC26 DD04 DD09 DD12 FF04 GG07 GG17 GG24 HH12 HH13 JJ03 JJ26 LL00 LL19 MM03 NN02 PP12 QQ23 QQ24 QQ31 TT02 2G051 AA65 AB14 AB20 BA01 BA20 BB01 CA04 DA07 EA12 EA14 EA17 5B047 AA07 AA12 AB04 BB04 CA19 CB01 BA19 BC19 BA19 BC19 BC01 BC19 DA01 DA07 DB03 DB06 DB09

Claims (2)

[Claims] An appearance inspection apparatus for performing a predetermined inspection by performing color image processing on color image data obtained by imaging an inspection object having a detection target portion having a surface roughness different from that of the surroundings, A camera for imaging the inspection object,
A first illuminating means for irradiating the object to be inspected with white illumination light from all directions at the time of imaging; and a second illuminating means for irradiating the object to be inspected with colored illumination light from the coaxial direction at the time of imaging. Appearance inspection device. 2. A visual inspection method for performing a predetermined inspection by performing color image processing on color image data obtained by imaging an inspection target having a detection target portion having a surface roughness different from that of the surroundings, When capturing an image of the inspection target with a camera, the inspection target is irradiated with colored illumination light from the coaxial direction, and the specular reflection light of the colored illumination light from the surface roughness of the detection target portion and the surroundings that is smaller is used. A visual inspection method characterized in that the detection target part is identified from the surroundings by receiving the light.