JPH10206139A - Surface unevenness inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inspection method in which the unevenness on the surface of an object to be inspected is detected surely even when the object to be inspected has a curved surface whose outer shape is rounded. SOLUTION: A surface illuminator 20 in which the range of an irradiation angle to a condenser body 2 has a size L as the product or lower of four times the tilt ϕ of a lump 3 multiplied by a distance D up to the condenser body 2 is used (i.e., L<4ϕ×D). The condense body 2 which is irradiated with the surface illuminator 20 is photographed by a television camera 5. Image data which is input from the television camera 5 is digitized. In the digitized image data, the number of parts which are dark to be an island shape in a region which is shining by the surface illuminator 20 and their area are computed. The existence of the lump 3 is judged on the basis of an obtained computed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for detecting irregularities (particularly, bumps and burrs) on the surface of electronic components such as capacitors.

[0002]

2. Description of the Related Art Conventionally, there are the following methods for detecting irregularities on the surface of an electronic component such as a capacitor. That is, FIG. 8 shows the shape of the capacitor 1 which is an example of the inspection target product, and the bump 3 is formed on the surface of the capacitor body 2.

FIG. 9 shows the configuration of an optical system used for inspection. Reference numeral 4 denotes illumination of a point light source for irradiating the condenser main body 2 to create a shadow of the bump 3. Reference numeral 5 denotes a condenser main body.
TV camera. Illumination 4 of the point light source
Is composed of spotlights and optical fibers.
As shown in FIG.
It is connected to the. The inspection device 6 includes a television camera 5
, An A / D converter 7 for converting an image input into digital data, an image memory 8 for storing digital data output from the A / D converter 7, a general-purpose memory 9,
PU10.

When the condenser body 2 is illuminated by the illumination 4 of the point light source, a shadow 11 due to the bump 3 is formed on the image captured by the television camera 5 as shown in FIG. Based on this, the unevenness is inspected according to the procedure shown in the flowchart of FIG.

That is, the image input from the television camera 5 is converted into digital data by the A / D converter 7 and stored in the image memory 8. Then, the image data of the capacitor body 2 stored in the image memory 8 is binarized to perform region division. This area division means that a certain area of the image is
A process in which a white region and a black region are divided into a white region (a portion brighter than the binarization level is defined as a white region, and a portion darker than the binarization level is defined as a black region). is there. FIG. 13 shows the television camera 5 shown in FIG.
FIG. 3 is a view obtained by dividing a captured image by white into a white region and a black region. According to this, the shadow 11 of the bump 3 is extracted as a connected region by region division.

FIG. 14 is a view of 3 × 3 pixels showing a method of determining the connection. A pixel is a unit of image data that is spatially divided for digitization. 12
Indicates the pixel at the point of interest. The digital data at the positions of a total of eight pixels 13 including the front, rear, left, right, and diagonally adjacent pixels 12 of the point of interest have the same color (white and white or black and white). If it is black, the connection is determined. In this case 8
It is called connection. (Note that 4 when no diagonally adjacent pixel is included)
Almost the same results can be obtained with concatenation. As a result, as shown in FIG. 13, the shadow 11 of the bump 3 is extracted and the area of the black area is calculated. It should be noted that the reference area is determined so that characters, dust, and the like are not erroneously determined. Also, the bump 3 itself is allowed to have a size equal to or less than a certain value, and is determined according to the tolerance. In some cases, an allowable value for the number of bumps 3 may be determined. The calculation of the area of the black region and the determination of the presence or absence of the bump 3 based on the calculated value are performed by the CPU 10 of the inspection device 6.

[0007]

However, in the conventional inspection method, the shadow 11 of the bump 3 cannot be formed unless the irradiation angle is lower than the inclination of the bump 3 to be detected. In the case of a curved surface having a rounded outer shape, a shadow due to the roundness of the condenser main body 2 is formed at a low irradiation angle, and therefore cannot be distinguished from the shadow 11 of the bump 3, whereby the area where the bump 3 can be detected is narrow. There was a problem that it was limited and hindered the examination.

When a character is imprinted on the surface of the capacitor body 2, there is a possibility that the character and the shadow 11 of the bump 3 may be erroneously recognized. Therefore, an object of the present invention is to reliably detect unevenness on the surface of a product to be inspected having a curved surface with a rounded outer shape.

[0009]

In order to achieve the above-mentioned object, according to the surface unevenness inspection method of the present invention, the range of the irradiation angle to the inspection object is four times the inclination angle of the unevenness to be detected. A surface illumination having a size equal to or less than the product of the distance to the target product is used, and the inspection target product is illuminated by the surface illumination. According to this, even if the inspection target product has a curved surface with a rounded outer shape, it is possible to reliably detect unevenness on the surface.

[0010]

The invention according to claim 1 of the present invention is characterized in that the range of the irradiation angle to the inspection target product is equal to or less than the product of four times the inclination angle of the unevenness to be detected and the distance to the inspection target product. Using an area illumination having a size of, an image obtained when the inspection object is irradiated with the area illumination is input as digital data from an image input unit, and the input digital data is stored in an image storage unit. It is characterized by calculating the number and area of island-like darkened areas in the area illuminated by surface illumination, and determining the presence or absence of irregularities based on the calculated value obtained. According to this, even if the inspection target product has a rounded curved surface, by using the surface illumination, it is possible to prevent the occurrence of the shadow due to the roundness of the inspection target product and generate the shadow of the unevenness. , Reliably detect surface irregularities Door can be.

[0011] The invention according to claim 2 is characterized in that a color filter for absorbing the surface color of the inspection object is provided between the inspection object and the image input unit. In addition, since irregularly reflected light generated when the inspection object is irradiated with the surface illumination can be reduced, it is easy to detect surface irregularities.

According to a third aspect of the present invention, a range of the irradiation angle to the inspection object is a surface illumination having a size equal to or less than a product of four times the inclination angle of the unevenness to be detected and the distance to the inspection object. The image when the object to be inspected is illuminated with this surface illumination is input as digital data from the image input unit, the input digital data is stored in the image storage unit, and the gloss shined by the surface illumination of the inspection object is used. The inclination of the contour of the part is calculated, and the presence or absence of unevenness is determined based on the obtained calculation value. According to this, the product to be inspected is a curved surface having a rounded outer shape. Also, by using the surface illumination, it is possible to prevent the shadow due to the roundness of the inspection target product and to generate the shadow of the unevenness, so that the unevenness on the surface can be reliably detected.

According to a fourth aspect of the present invention, a color filter for absorbing the surface color of the inspection object is provided between the inspection object and the image input unit. In addition, since irregularly reflected light generated when the inspection object is irradiated with the surface illumination can be reduced, it is easy to detect surface irregularities.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. Note that the same members as those in the above-described conventional surface unevenness inspection method are also used for the drawings, and are denoted by the same reference numerals and description thereof is omitted.

(Embodiment 1) As shown in FIG. 8, a capacitor 1 is an example of a product to be inspected, and a bump 3 is formed on a capacitor body 2. FIG. 2 shows a configuration of an optical system used for inspection, and 20 is a condenser main body 2.
And 5 is a television camera (an example of an image input unit) for photographing the condenser body 2. The surface illumination 20 irradiates light from a plane having a predetermined area using, for example, a large number of optical fibers. As shown in FIG. 10, the television camera 5 is connected to an inspection device 6.
Is composed of an A / D converter 7, an image memory 8 (an example of an image storage unit), a general-purpose memory 9, and a CPU 10.

As shown in FIG. 2, a color filter 21 is provided between the condenser body 2 and the lens of the television camera 5, and the color of the color filter 21 is a surface color of the condenser body 2. Is selected to be a complementary color to.

FIG. 1 is a diagram showing conditions for the size of the surface illumination 20. Since the surface of the condenser body 2 is a rounded curved surface, the size of the portion to be reflected is determined by the size of the surface illumination 20 itself. In general, when the surface has a large curvature such as the condenser 1, the surface illumination 20 needs to be considerably large in order to increase the reflection area. However, if it is too large, the bump 3 will be reflected and the shadow of the bump 3 cannot be formed. Therefore, it is necessary to use the surface illumination 20 having a size such that the bump 3 having the minimum inclination to be detected is not reflected. is there. Therefore, assuming that the minimum inclination of the bump 3 to be detected is φ, the incident angle F of the surface illumination 20 must be within ± 2φ. That is, if the size of the surface illumination 20 is L and the distance from the surface illumination 20 to the condenser body 2 is D, then L <4φ × D.

When the angle of the inclination φ is large, the ratio of the irregularly reflected light 22b (see FIG. 2), which is a component of light other than the regular reflected light 22a (see FIG. 2), becomes large. In many cases, characters are stamped on the surface of the capacitor body 2. However, when the component of the irregularly reflected light 22b is large, the printed characters are conspicuous. On the other hand, for example, the capacitor body 2
If the surface is brown, the brown is irregularly reflected. By using the blue color filter 21 which is a complementary color to the brown, the brown is cut, the component of the irregularly reflected light 22b is reduced, and the inspection becomes easy.

When the condenser body 2 is illuminated using the above-described surface illumination 20, an image as shown in FIG. Since the surface of the capacitor body 2 is glossy, illumination is reflected. Reference numeral 23 in FIG. 3 denotes a portion where the surface illumination 20 is reflected. In contrast, 24
Is a certain portion of the bump 3, and the area illumination 20 is not reflected and is shadowed. As described above, even when the capacitor body 2 has a curved surface with a rounded outer shape, by using the surface illumination 20 having the size L as described above, it is possible to prevent the shadow due to the roundness of the capacitor body 2 from occurring and to reduce the shadow. Since the shadow 24 of 3 can be generated, the bump 3 on the surface can be reliably detected.

The processing after the TV camera 5 captures the shadow 24 of the bump 3 of the condenser body 2 is the same as the conventional processing.
As shown in the flowchart of FIG. 12, the image data of the capacitor body 2 that has been digitized by the A / D converter 7 and stored in the image memory 8 is binarized to perform region division. FIG. 4 is a diagram in which a rectangular region 25 inside the outline of the capacitor body 2 is divided into regions,
Are extracted as connected regions by region division.
Here, attention is focused on bump 3. Therefore, only the black region surrounded by the white region may be extracted.

The extraction of only the black region is performed by using 3 × 3 pixels as shown in FIG. 14, as in the prior art, whereby the shadow 24 of the bump 3 is extracted and the area of the black region is measured. If there is something larger than the reference area, it is determined to be bump 3. Note that the reference area is determined so that characters and dust are not erroneously determined. Also, about Cobb 3 itself,
Since the size below a certain value is allowed, it is determined according to this allowable value. In some cases, an allowable value for the number of bumps 3 may be determined.

(Embodiment 2) The present embodiment 2 is an effective inspection method particularly when the bump 3 is located near the edge of the surface of the capacitor body 2. The inspection method will be described below. explain. Note that the same members as those in the conventional surface unevenness inspection method described above and the surface unevenness inspection method described in Embodiment 1 are also used in the drawings and are assigned the same reference numerals and description thereof is omitted.

When the condenser body 2 is illuminated using the surface illumination 20, an image as shown in FIG. Since the surface of the capacitor body 2 is glossy, illumination is reflected. Reference numeral 31 in FIG. 6 denotes a portion where the surface illumination 20 is reflected. On the other hand, reference numeral 32 denotes a portion where the bump 3 is present, and the surface illumination 20 is not reflected and is shadowed. As described above, even if the capacitor body 2 has a rounded curved surface, the use of the surface illumination 20 prevents the shadow due to the roundness of the capacitor body 2 and generates the shadow 32 of the bump 3. Therefore, it is possible to reliably detect unevenness on the surface.

The processing after the TV camera 5 captures the shadow 32 of the bump 3 of the condenser body 2 is converted into digital data by the A / D converter 7 and stored in the image memory 8 as shown in the flowchart of FIG. Is done. Then, the image memory 8
The image data of the capacitor body 2 stored in the storage area is binarized and divided into a white area and a black area, and a glossy portion (that is, a white area) of the capacitor body 2 is extracted by the surface illumination 20.

Based on this, as shown in FIG. 5, the outline 34 of the glossy portion 33 of the condenser body 2 by the surface illumination 20
Is extracted, and the inclination θ of the portion 35 disturbed by the shadow 32 of the bump 3 is calculated. That is, scanning is performed at a constant distance B in the direction A at right angles to the contour 34, and a point where the white area and the black area are interchanged is defined as a contour point 36. When the adjacent contour points 36 are connected with a straight line C, the inclination θ of the straight line C in the portion 35 disturbed by the shadow 32 of the bump 3 is obtained.
Is greatly changed as compared with the others, and the inclination θ is calculated. If the obtained value of the inclination θ is larger than the reference value, it is determined that the bump 3 is present.

The constant distance B is set so that the bump 3 to be detected is not missed and the minute bumps are not detected.
Is set to be about one-fourth to half of the size of. Further, the reference value is determined according to an allowable value of a defect limit of the bump 3 to be inspected. Further, there is a case where an allowable value of the number is determined.

Further, similarly to Embodiment 1 described above,
By using the color filter 21, the surface color of the capacitor body 2 may be cut, and the component of the irregularly reflected light 22b may be reduced.

In each of the above-described embodiments, the capacitor 1 has been described as an example of the inspection target product. However, the same inspection method can be applied to other electronic components to detect surface irregularities.

[0029]

As described above, according to the first aspect of the present invention, even if an object to be inspected has a curved surface with a rounded outer shape, it can be inspected by using surface illumination. As a result, it is possible to prevent the occurrence of a shadow due to the roundness and to generate the shadow of the unevenness, so that the unevenness on the surface can be reliably detected.

According to the second aspect of the present invention, irregularly reflected light generated when an object to be inspected is illuminated by surface illumination can be reduced, so that surface irregularities can be easily detected. According to the third aspect of the present invention, even if the inspection target product has a rounded curved surface, the use of the surface illumination prevents the shadow due to the roundness of the inspection target product and generates the uneven shadow. Therefore, surface irregularities can be reliably detected.

According to the fourth aspect of the present invention, irregularly reflected light generated when an object to be inspected is illuminated by surface illumination can be reduced, so that surface irregularities can be easily detected.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating conditions of the size of surface illumination used in a surface unevenness inspection method according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a diagram illustrating a configuration of an optical system device used in a surface unevenness inspection method according to Embodiments 1 and 2 of the present invention.

FIG. 3 is an image picked up by a television camera used in the surface unevenness inspection method according to the first embodiment of the present invention.

FIG. 4 is a diagram in which image data obtained by the surface unevenness inspection method according to the first embodiment of the present invention is subjected to region division processing into a black region and a white region.

FIG. 5 is a diagram for explaining a method of extracting a contour of a glossy portion of image data obtained by a surface unevenness inspection method and calculating a tilt according to the second embodiment of the present invention.

FIG. 6 is an image picked up by a television camera used in the surface unevenness inspection method according to the second embodiment of the present invention.

FIG. 7 is a flowchart showing a processing step of the surface unevenness inspection method according to the second embodiment of the present invention.

FIG. 8 is a perspective view of a conventional capacitor.

FIG. 9 is a diagram showing a configuration of an optical system device used in a conventional surface unevenness inspection method.

FIG. 10 is a diagram showing a configuration of an inspection apparatus used in a conventional surface unevenness inspection method.

FIG. 11 is a photographed image of a television camera used in a conventional surface unevenness inspection method.

FIG. 12 is a flowchart showing a processing step of a conventional surface unevenness inspection method.

FIG. 13 is a diagram in which image data obtained by a conventional surface unevenness inspection method is subjected to area division processing into a black area and a white area.

FIG. 14 is a diagram illustrating a method of determining connection of image data obtained by a conventional surface unevenness inspection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condenser (product to be inspected) 3 Ridge (irregularity) 5 TV camera (image input part) 8 Image memory (image storage part) 20 surface illumination 21 Color filter 33 Glossy part 34 Outline φ Tilt of bump D From surface illumination to condenser Distance L Size of surface illumination θ Slope of contour of glossy part

Claims (4)

[Claims] 1. A surface illumination having a range of an irradiation angle to an object to be inspected having a size equal to or less than a product of four times an inclination angle of unevenness to be detected and a distance to the object to be inspected is used. The image when the target product is illuminated is input as digital data from the image input unit, and the input digital data is stored in the image storage unit, and is darkened like an island in the area illuminated by the surface illumination of the test target product. A method for inspecting surface unevenness, comprising calculating the number and area of a portion having an irregularity and determining the presence or absence of irregularity based on the calculated value. 2. The surface unevenness inspection method according to claim 1, wherein a color filter for absorbing the surface color of the inspection object is provided between the inspection object and the image input unit. 3. A surface illumination whose irradiation angle range to the inspection object is less than or equal to a product of four times the inclination angle of the unevenness to be detected and a distance to the inspection object is used. The image when the target product is illuminated is input as digital data from the image input unit, the input digital data is stored in the image storage unit, and the inclination of the contour of the glossy part illuminated by the surface illumination of the test target product is calculated. And a method for inspecting the surface unevenness based on the obtained calculated value. 4. The method according to claim 3, wherein a color filter for absorbing a surface color of the inspection object is provided between the inspection object and the image input unit.