JPH043802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a chip component displacement inspection method for inspecting the chip displacement state of a chip component mounted on a printed wiring board.

(Background Art) For example, when automatically measuring the displacement of chip components on a printed wiring board on which chip components are mounted, conventionally, as shown in FIG. By lighting the solder surface 12 such as
The deviation of the chip components was measured by the deviation of the solder surface. That is, an inspection area S as shown in C is set in the binarized image 12' obtained by binarizing as shown in B, and a reference point O is set.
The distance from to the contour was determined by image processing, and this value was used as the amount of deviation.

However, the soldering conditions of chip parts vary widely; for example, the solder surface 12A with insufficient solder and the solder surface 12B with excess solder shown in FIG. ' are moth-eaten, making it difficult to see the contours of the solder surfaces 12A and 12B, and as shown in FIG.
If there is a letter 14 in it, if it has been trimmed 15, or if it is a whitish chip part,
At the binarization threshold level that produces the outline of the solder surface 12, characters 14, trimming 15, whitish parts, etc. appear as noise 14', 15', so complex image processing or a complex illumination system is required to remove them. was necessary.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned technical problems and provide a chip component displacement inspection method that can automatically and highly accurately inspect the displacement state of chip components.

(Disclosure of invention) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of an inspection device embodying the present invention. A feature of the present invention is that by combining an image of the solder surface obtained by horizontally emphasized illumination and an image of the solder surface obtained by epi-illumination, an accurate outline of the solder surface can be obtained without being affected by the condition of the solder surface. It's about putting it out. In other words, the angular part of the soldering surface that is not flat can be illuminated with lateral emphasis diffused lighting to highlight the angular part of the soldering surface.
An image is taken with an ITV camera, and epi-illumination is applied to the flat part of the solder surface, and the specularly reflected light is imaged with an ITV camera. As a result, images can be taken with the solder surface shining the brightest depending on the angle of the solder surface, so the binarization threshold level can be set sufficiently high when binarizing. It is possible to prevent noise from appearing in the binarized image due to image chipping, characters, trimming, chip part colors, etc.

In FIG. 1, lateral emphasis illumination is achieved by irradiating light from a light source 5 laterally onto a chip component 11 on a printed wiring board 10 using a fiber ring light guide 3 for inward irradiation. can get. Note that the light emitted from the end of the fiber ring light guide 3 for inward irradiation is milky white, and due to the dome-shaped diffuser plate 7, the steeper the angle, the weaker the light irradiated onto the solder surface of the chip component 11. The result is diffused light. On the other hand, epi-illumination is obtained by irradiating light from the light source 4 from above onto the chip component 11 through the fiber ring light guide 2 for downward irradiation. Note that switching between the two illuminations is performed using the shutter 6. Further, the ITV camera 1 is provided above the illumination section, and the signals obtained by imaging are subjected to image processing such as binarization and deviation determination in the image processing section 8.

FIG. 2A shows a raw image of the chip component 11 within the imaging field of view, and the chip component 11 is irradiated with lateral emphasis illumination from the light source 5, the fiber light guide 3, and the diffuser plate 7. ITV
When an image is captured by the camera 1 and binarized at a threshold level higher than the brightness of the text, trimming, and chip component color, as shown in FIG. A binarized image 12' in which the angular portion becomes white is obtained. here,
Parts brighter than the binarization threshold level are white, but
Needless to say, the same is true even if it is reversed.

Then, store this binarized image 12',
Switch to epi-illumination using light source 4 and fiber ring light guide 2, and take an image again with ITV camera 1.
Similarly, when binarized at a threshold level higher than the brightness of the text, trimming, and chip component color, a binarized image 12 is obtained in which the soldered part of the chip component 11 with an inclination of about 5 degrees or less becomes white, as shown in FIG. 2C. Get ″.
By combining this binarized image 12'' with the previously stored binarized image 12' of horizontally emphasized illumination, the text, trimming, and chip part color portions are created as shown in FIG. A binarized image 12 of only the soldered portions that do not appear can be obtained.

Note that in a normal soldering state, parts with a soldering inclination of about 45 degrees or less appear white, but by soldering to a less glossy surface, the maximum inclination that can be detected as an image can be increased.

As described above, by calculating the distance of the solder surface contour from the reference point based on the binarized image obtained by the synthesis, it is possible to accurately inspect the amount of deviation of the chip component.

(Effects of the Invention) As described above, in the present invention, in a method of inspecting the amount of deviation of a chip component mounted and soldered on a printed wiring board from an image of the solder surface, horizontally emphasized light is applied to the solder surface. A binarized image at a threshold level where angled solder surfaces appear white when illuminated with light and captured with a television camera, and an image of flat portions of solder when illuminated with epi-emphasized light and imaged with a television camera. By combining the binarized image with a threshold value that makes the surface appear white, an image faithful to the solder surface is constructed, and this image is used to measure the amount of deviation of the chip component. (a) Chip component displacement inspection is possible without being affected by solder shape.

(b) It is possible to inspect the deviation of chip parts without being affected by the color, text, trimming, etc. of the chip parts.

(c) Improved chip component misalignment inspection accuracy.

(d) Lighting configuration becomes simpler.

There are other effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an inspection apparatus embodying the present invention, FIG. 2 is an explanatory diagram showing image composition, and FIGS. 3 to 5 are explanatory diagrams of a conventional inspection method. 1... ITV camera, 2, 3... fiber ring light guide, 4, 5... light source, 6... shutter, 7... diffuser plate, 8... image processing section, 10...
Printed wiring board, 11...Chip component, 12...Solder surface, 12'...Binarized image of the solder surface under lateral emphasis illumination, 12''...Binarized image of the solder surface under epi-illumination, 12... ...Binarized image of the synthesized solder surface.

Claims (1)

[Claims] 1 In a method of inspecting the amount of misalignment of chip components mounted and soldered on a printed wiring board from an image of the solder surface, the solder surface is irradiated with horizontally emphasized light and imaged with a television camera, and the solder surface at an angle is The image is binarized at a threshold level that makes the solder surface appear white, and the image is captured using a TV camera by illuminating the solder surface with epi-illumination-enhanced light, and the image is binarized at a threshold level that makes the solder surface appear white in flat areas. , compose an image faithful to the solder surface,
A chip component deviation inspection method characterized by measuring the amount of chip component deviation using the image.