JPH029506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an imaging illumination device that is advantageously implemented for inspecting the soldering condition of electronic circuit elements called chips, which are attached to printed wiring boards, for example.

BACKGROUND ART For example, when automatically soldering printed wiring boards on which electronic circuits are mounted, it is necessary to inspect the soldering condition to eliminate solder shortages and missing solders. Correct operation is achieved. Therefore, the inspection method shown in FIGS. 1 and 2 has conventionally been used. Electronic circuit elements 2 and lead wires 3 are attached to printed wiring board 1 with solders 4 and 5, respectively. An industrial television camera 6 is provided above the printed wiring board 1 to inspect the solder surfaces 4a, 5a of the solders 4, 5. Solder side 4
A, 5a is inspected using an illumination device 7 that emits a beam of light as shown in FIG. 1, or an illumination device 8 that emits line light. In the illumination device 7 that irradiates the beam light in this way, the solder surfaces 4a, 5a have complicated shapes, so the solder surfaces 4a, 5a have complicated shapes.
It is difficult to uniformly brighten the entire area a, and it is not possible to accurately detect whether the soldering condition is good or bad. In addition, the illumination device 8 that uses a light cutting method that uses line light can detect the three-dimensional features of the solder surfaces 4a and 5a, but because of the line light, complex shape recognition is required, and it is necessary to scan the entire screen. It is necessary to capture and view the optically sectioned image, which takes time for inspection. Furthermore, since solder defects cannot be recognized unless the solder attachment position is fixed to some extent, it is difficult to deal with problems such as chip displacement.

Purpose The purpose of the present invention is to solve the above-mentioned technical problem,
An object of the present invention is to provide an imaging illumination device that can accurately and easily detect glossy flat parts and uneven parts such as soldered states of an object to be detected.

Structure of the Invention The present invention includes: a first light source that is arranged in a ring shape with the detected object as the center near directly above the detected object and emits irradiation light toward the detected object; and above the detected object. and below the first light source, are arranged in a ring shape with the object to be detected as the center, and irradiate the irradiation light toward the object to be detected, the luminous intensity of which increases as it approaches the object to be detected from closer to the first light source. and a second light source configured as follows, the luminous intensity of each of the first light source and the second light source is freely variable, and an imaging means is provided for capturing an image of the object to be detected at a position near directly above the object to be detected. This is an imaging illumination device characterized by:

Embodiment FIG. 3 is a sectional view of an embodiment of the present invention, FIG. 4 is a sectional view taken from the cutting plane line - in FIG. 3, FIG. 5 is a developed view of the first holding member 9, and FIG. 6 2 is a sectional view of the second holding member 10. FIG. The lead wires 12 and their solder surfaces 13 to be inspected on the printed wiring board 11 are as follows:
This is the object to be detected 15 . An optical fiber 28 and a light source 29, which will be described later, constitute a first light source, and in this first light source, the optical fiber 28
are held by the first holding member 9 and arranged in a ring shape with the detected object 15 as the center, and the detected object 1
The irradiation light is irradiated toward 5. The second light source includes an optical fiber 20, a light source 21, high frequency fluorescent lamps 22 and 23, and a diffusion member 14, as will be described later. Above the object to be detected 15 and below the first light source described above, an optical fiber 20 and fluorescent lamps 22 and 23 are held by the second holding member 10 with the object to be detected 15 as the center. , a diffusion member 14 are arranged in an annular manner, and irradiate the irradiation light toward the object 15 to be detected. The luminous intensity of this second light source varies from near the first light source (upper part of FIG. 3) to the detected object 15.
It is constructed so that it becomes larger as it approaches (that is, as it moves downward in FIG. 3).

The drive shutter 30 allows the luminous intensity of each of the first light source and the second light source to be varied. The detected object 15 is imaged by industrial television cameras 25 and 26, which are imaging means, at a position directly above it.

To further describe the configuration of the second light source,
The object to be detected 15 is covered by a dome-shaped diffusion member 14 . This diffusion member 14 is made of a translucent material such as acrylic resin. A through hole 16 is formed in the diffusion member 14 at a position directly above the object to be detected 15 . The diffusion member 14 is covered with a dome-shaped light-shielding cover body 17.
Lower end 14a of diffusion member 14 open to printed wiring board 11 side and lower end 17a of cover body 17
is connected to an annular bottom plate 18 extending in the horizontal direction. An annular second holding member 10 is fixed on the bottom plate 18 so as to surround the outer peripheral surface 14b of the diffusion member 14. As shown in FIG. 6, the second holding member 10 has insertion holes 19 extending in the radial direction formed over the entire circumference, and a plurality of optical fibers 20 are individually inserted into each insertion hole 19. The end surface 20a of each optical fiber 20 is arranged facing the diffusion member 14. The base end 20b of this optical fiber 20 is
It is arranged facing the light source 21 arranged outside the cover body 17. Above the second holding member 10 and inside the cover body 17, annular fluorescent lamps 22 and 23 that are energized by high frequency power are arranged. The fluorescent lamps 22 and 23 provide diffused light from inside the cover body 17 toward the object 15 to be detected with uniform luminous intensity in the circumferential direction around the object 15 from diagonally above. Here, the second light source is constituted by the light source 21, the optical fiber 20, and the fluorescent lamps 22 and 23 as described above.

A through hole 24 is formed in the cover body 17 at a position directly above the object to be detected 15, and the industrial television cameras 25 and 26 are provided through the through hole 24 and the through hole 16 of the diffusion member 14. Object 15 to be detected placed at a predetermined position
can be imaged.

To further describe the first light source, the cover body 1
An annular first holding member 9 shown in FIG. 4 is fixed at a position surrounding the through hole 24 of No. 7. A plurality of insertion holes 27 are formed around the entire circumference of the first holding member 9, and a plurality of optical fibers 28 constituting the first light source are individually inserted into the insertion holes 27. Each end face 28a of the optical fiber 28 shown in FIG.
The base end portion 28b is disposed facing a light source 29 provided outside the cover body 17, and the light source 29 and the light source 21 are formed into a semicircular opaque or translucent light-shielding device for adjusting the amount of transmitted light. The light intensity is selectively adjusted by the switching operation of the driving shutter 30 that rotates the plate 30a, and the light is sent to the optical fibers 28, 20, so that the luminous intensity of each of the first light source and the second light source is variable. I am free to do so.

An industrial television camera 25 is arranged on a vertical line connecting the object to be detected 15, the center of the through hole 16 of the diffusion member 14, and the center of the through hole 24 of the cover body 17, and an industrial television camera 25 is placed on the side thereof. A television camera 26 is arranged. Light from the object to be detected 15 is incident on a half mirror 31 interposed between the object to be detected 15 and the industrial television camera 25 . The straight light from the half mirror 31 is incident on the imaging lens of the industrial television camera 25 via the blue filter 32. Also, the half mirror 31 from the detected object 15
A part of the light reflected at a right angle by the mirror 34 is bent by 90 degrees and is incident on the imaging lens of the industrial television camera 26 via the red filter 35. By dividing the image of the object to be detected 15 into the two industrial television cameras 25 and 26 in this way, defective solder parts such as insufficient solder on the object to be detected 15 as described later can be distinguished and detected. becomes possible.

FIG. 7 is a diagram showing the distribution state of illumination, and FIG.
This figure and FIG. 9 are diagrams showing horizontally diffused light and its principle. FIG. 10 is a diagram showing the imaging state in the diffused illumination of FIG.
This is a dark area where the amount of light entering the area is small. Optical fibers 20, 28 and high frequency fluorescent lamps 22, 23
The respective lights are irradiated toward the object to be detected 15 as shown in FIG. In the diffusion member 14 of the second light source, the optical fiber 20 and the fluorescent lamp 2
The intensity vector of the light from 2 and 23 is a diffused light as shown by the arrow A that increases as it approaches the detected object 15, and the luminous intensity ratio between the horizontal direction and the vertical direction is, for example, 10:1 to 1. It is set to 10:5. The distribution of this luminous intensity ratio is based on the fluorescent lamps 22, 2
3, the positional relationship of the optical fiber 20 with respect to the object to be detected 15, and the light intensity, and the diffusing member 14 smoothes the change in the light intensity. For example, by making the light intensity of the fluorescent lamp 23 stronger than that of the fluorescent lamp 22 and adding the light intensity of the optical fiber 20, a distribution as shown by arrow A can be obtained, and the luminous intensity ratio can be adjusted as desired by changing the light intensity ratio of each illumination. The value can be set to

Further, the intensity vector of the light from the optical fiber 28 of the first light source is substantially vertically incident light as shown by arrow A'.

Here, when the first light source is used, the light amount of A' is the main one, and of the light amount of A, the light from the optical fiber 20 is blocked or weakened by the drive shutter 30, and the fluorescent lamps 22 and 23 are activated by high frequency power. The amount of light is adjusted by adjusting .

Further, when the second light source is used, the light amount of A is the main one, and the light amount of A' is a small value because the light amount of the optical fiber 28 is blocked or weakened by the drive shutter 30.

Generally, on the solder surface 13 of the object to be detected 15, as shown in FIG. Because it is possible to illuminate the area, it looks bright even with a small amount of light. However, as shown in Figure 9, in areas where the inclination angle θ2 is 45 degrees or more, the light is placed upwards as shown by arrow B''. It is not reflected with a large luminous intensity toward the industrial television cameras 25 and 26, and therefore the shaded area of the solder surface 13 appears dark as shown in FIG. 10. Such a shaded area of the solder surface 13 is close to a mirror surface, and the amount of light reflected directly above is extremely small.Therefore, as shown by arrow A in FIG. , by setting the luminous intensity strongly, the solder surface 13 has an inclination angle of 45
Even if the angle of inclination θ2 is more than 45 degrees, by increasing the magnitude of the diffused light toward the cameras 25 and 26 indicated by arrow B'' in Fig. 9, the soldered part where the inclination angle θ2 is more than 45 degrees will be brightened. Furthermore, as shown by arrow B' in FIG. 8, the amount of double reflected light can also be increased to increase the amount of light incident on the cameras 25 and 26.

Blowhole 3 whose cross section is shown in FIG. 11
6. The second light source is used to detect blockage of the lead hole, whose cross section is shown in Figure 12, Figure 1, proximity, whose cross section is shown in Figure 1, and chip displacement, whose plane is shown in Figure 14. . In each plan view of FIG. 11, FIG. 12, FIG. 13, FIG. 2, and FIG. 14, dark portions are indicated by diagonal lines. At this time, the industrial television cameras 25 and 26
3, the outline of the solder surface 13 is clearly visible, the blowhole 36 becomes dark as shown in FIG. 11 2 and FIG. 12 2, and the lead hole 3 is blocked.
The part numbered 7 becomes brighter. When the second light source is used, during normal soldering, the entire solder surface 13 becomes bright and the hole part becomes dark, so if the shape, area, etc. of the dark part are extracted by image processing,
It is possible to detect blowhole defects and lead hole blocking defects. Similarly, regarding the proximity shown in FIG. 13 and the chip deviation shown in FIG.
It is possible to measure the deviation amount d2 of No. 5 by image processing and detect a proximity defect or a chip misalignment defect. In this FIG. 14, reference numerals 50, 51,
52 is a land made of copper foil, and the chip component 5
5 has terminals 53 and 54 to be soldered to lands 50 and 51.

Solder shortage 39, the cross section of which is shown in FIG.
40, 16. Copper surface 41, 4 whose cross section is shown in FIG.
2 and 17. In detecting the excess solder portion 43 whose cross section is shown in FIG.
Use a light source. By irradiating the solder surface 13 with vertical reflected light in this way, the flat part shines brightly, and when the solder surface 13 is viewed with industrial television cameras 25 and 26, the solder surface 13 is shown in FIGS. 15-2 and 16-2. As shown in the plane in FIG. 17, the solder deficient areas 39 and 40, the copper exposed areas 41 and 42, and the solder excess area 43 become brighter, and the shape and area of these bright areas are determined by image processing. By measuring it, it is possible to distinguish it from a good solder surface. The copper surface exposed portions 41 and 42 are the blue filter 32,
It can be detected by separating the red image into a red image and a blue image by the action of the red filter 35, and extracting the copper color portion from the difference between the two images. Excessive solder is caused by the bright area 43 in the center of the land as shown in FIG.
Detection becomes possible when it appears large.

By performing the switching operation of the drive shutter 30 at high speed in this manner, the vertically reflected light from the first light source and the horizontally diffused light from the second light source are selectively irradiated onto the object to be detected 15 with the light intensity adjusted. By doing so, it is possible to reliably detect defects in the solder surface 13 of the object to be detected 15.

In the above-described embodiment, fluorescent lamps 22 and 23 energized by high-frequency power were used as intermediate illumination, but an optical fiber may also be used. Further, the diffusion member 14 is not limited to milky white acrylic resin, and may be made of, for example, frosted glass other than milky white.

Effects According to the present invention, the flat part of the object to be detected is detected by the reflected light from the first light source, and the flat part of the object is detected by the light from the second light source.
By accurately detecting the shiny, uneven surface of the object to be detected and by changing the luminous intensity of the first and second light sources, it is possible to detect various types of defects such as the solder surface of the object. This makes it possible to conduct inspections.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining the prior art, FIG. 3 is a sectional view of an embodiment of the present invention, and FIG.
The figures are a sectional view taken from the cutting plane line - in Fig. 3, Fig. 5 is a developed view of the first holding member 9, Fig. 6 is a sectional view taken from the cutting plane line - in Fig. 3, and Fig. 7. 8 and 9 are diagrams showing the principle of horizontally diffused light, and FIG.
11 is a cross-sectional view showing the blowhole 36, FIG. 11 is a plan view showing the blowhole 36, and FIG. 12 is a cross-sectional view showing the blockage of the lead hole. 2 is a plan view showing how the lead hole is blocked, FIG. 13 is a sectional view showing the proximity of the solder surface 13 in FIG. 13, and FIG.
14 is a plan view showing the proximity of the detected object 15.
15 is a cross-sectional view showing solder shortage, and FIG. 15 2 is a plan view showing solder shortage.
FIG. 16 1 is a cross-sectional view showing the exposed state of the copper surface.
6. Figure 2 is a plan view showing the exposed state of the copper surface, Figure 17.1 is a sectional view showing the state of excess solder, and Figure 17.2.
1 is a plan view showing a state of excess solder; FIG. 1, 11...Printed wiring board, 6, 25, 26...
...Industrial TV camera, 9...First holding member, 1
0...Second holding member, 13...Solder surface, 14...
...Diffusion member, 15... Object to be detected, 20, 28...
...optical fiber.

Claims (1)

[Scope of Claims] 1. A first light source arranged in a ring shape with the detected object as the center near the detected object, and irradiating light toward the detected object, and above the detected object. and below the first light source, are arranged in a ring shape with the object to be detected as the center, and irradiate the irradiation light toward the object to be detected, the luminous intensity of which increases as it approaches the object to be detected from closer to the first light source. and a second light source configured as follows, the luminous intensity of each of the first light source and the second light source is freely variable, and an imaging means is provided for capturing an image of the object to be detected at a position near directly above the object to be detected. An imaging illumination device characterized by: