JPH02278105A - Inspecting apparatus for soldering - Google Patents

Abstract

PURPOSE:To determine the quality of soldering by binary-coding an image of a soldered part and by calculating an area by measuring the number of pixels. CONSTITUTION:In a chip component 1, an electrode 2 is soldered to a pad 4 on a printed circuit board 3 and a solder fillet 5 is formed. An illumination 6 illuminates soldered parts 1 to 5, objects of inspection, from above, a camera 7 outputs gradated-image signals (a) of the soldered parts 1 to 5, and a binary- coding circuit 8 binary-codes the signals (a) and outputs binary-coded image signals (b) comprising '1' corresponding to a light part and '0' corresponding to a dark part. A window generating circuit 9 generates an inspection window 12 in sizes set beforehand and outputs inner-window binary-coded image signals (c), while an area measuring circuit 10 measures the number of pixels of '1' contained in the signals (c) and outputs a measured-area signal (d). A determination circuit 11 compares a measured area with a prescribed area set beforehand and thereby the quality of soldering can be determined.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a soldering inspection device, particularly to inspecting the soldering state of surface mount components such as chip components, SOPs, and QFPs soldered to printed circuit boards. This invention relates to a soldering inspection device that can be used.

[Conventional technology]

FIG. 4 is a side view showing a conventional soldering inspection device. The chip component 20 has an electrode 21 soldered to it and a fillet 22 formed on the pad 4 of the printed circuit board. lighting 2
3, the fillet 22 is irradiated with irradiation light. The camera 24 inputs an image of the fillet 22 portion, and the determination unit 2
The image signal i is output to 5. In the determination unit 25, the image signal i
is input, and it is determined whether the specularly reflected light of the irradiated light is incident on the camera 24 based on whether there is a point with extremely high brightness. If it is determined that the specularly reflected light is incident on the camera 24, it is normal 2. If not, it is determined to be defective.

[Problem to be solved by the invention]

The conventional soldering inspection device described above judges good and defective products based on the presence or absence of specularly reflected light incident on the camera 24, so the specularly reflected light depends on the shape of the fillet, and some defects may not be detected, resulting in non-defective products. There was a drawback that parts of the product could be incorrectly determined to be defective.

[Means to solve the problem]

The soldering inspection device of the present invention illuminates the soldered portion to be inspected from an upper light source and converts a grayscale image captured by a camera installed above the soldered portion into a binary image.
a digitization circuit; a window generation circuit that generates an inspection window having a preset shape and size corresponding to the soldered portion in the binarized image output by the binarization circuit; an area measurement circuit that outputs a measurement area signal obtained by measuring the number of pixels of one value of the binarized image;
and a determination circuit that compares the measured area signal with a preset constant value to determine the quality of the soldered portion.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In addition, although this embodiment will be explained using a chip component as an example,
The present invention does not limit the parts to be inspected to chip parts.

In a chip component 1 shown in FIG. 1, an electrode 2 is soldered to a pad 4 on a printed circuit board 3, and a solder fillet 5 is formed.

The light 6 illuminates the soldering parts 1 to 5 to be inspected from above.
The camera 7 captures images of the soldering parts 1 to 5 to be inspected from above and outputs a grayscale image signal a. The binarization circuit 8 inputs the grayscale image signal a and converts it into "1°" corresponding to the bright part.
' and 'OII corresponding to dark areas are binarized and a binary image signal is output. The window generation circuit 9 generates an inspection window 12 of a preset size, and generates a binary image within the inspection window 12. The area measurement circuit 10 outputs the in-window binary image signal C that only extracts the area.
inputs the in-window binary image signal C, measures the number of pixels of "1'° included in the in-window binary image signal C, and outputs the measured area signal d. The determination circuit 11 receives the measured area signal d. is input, and if the measured area is smaller than a preset constant area, it is determined that the soldering is good, and if it is larger, the soldering is determined to be defective.

Next, the principle of inspection in this embodiment will be explained using FIGS. 2 and 3.

From FIG. 2, irradiation lights e, f, and g from the illumination 6 are emitted from the electrodes 2 and 2, respectively. Solder fillet 5. The light is irradiated onto the pad 4, and the reflected light becomes e', f', and g'. Since the electrode 2 and the pad 4 are almost horizontal, the reflected light e' and g from the electrode i2 and the pad 4 are
' is reflected upward and enters the camera 7, but since the solder fillets are not horizontal, the reflected light f' from the solder fillet 5 does not enter the camera 7.

When soldering is performed normally, the binary image signal has the pattern shown in FIG. 3(a). In FIG. 3, the shaded area indicates the binary image signal ``1'', and the unshaded area indicates the binary image signal ``0''.

FIG. 3(b) is a pattern diagram of a binary image signal when the amount of solder is small. The area of O'' indicating the solder fillet portion 5 is smaller than in the normal case because there are fewer oblique portions where reflected light does not enter the camera.

Therefore, the inspection window 12 including the solder fillet portion 5
If the area of II I II is smaller than a preset pass/fail judgment threshold, it can be determined that the soldering is good, and if it is larger, it can be determined that the soldering is defective.

〔Effect of the invention〕

The soldering inspection device of the present invention detects soldering defects by receiving reflected light from illumination from above the soldering part with a camera installed above the soldering part, and determining the area of the part where the camera does not receive the reflected light. As a result, soldering defects can be detected with high accuracy regardless of the shape of the soldered part.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the state of reflected light from the soldering part by the illumination 6 shown in FIG. 1, and FIG. 3 is a binary value shown in FIG. 1. FIG. 4 is a side view showing a conventional soldering inspection device. ■... Chip component, 2... Electrode, 3... Printed circuit board, 4... Pad, 5... Solder fillet, 6...
...Lighting, 7...Camera, 8...Binarization circuit, 9.
...Window generation circuit, 10...Area measurement circuit, 1
1... Judgment circuit, 12... Inspection window, 20.
...Chip component, 21...Electrode, 22...Solder fillet, 23...Lighting, 24...Camera, 25...
- Judgment unit, a... Grayscale image signal, b... Binary image signal, C... Binary image signal within window, d... Measurement area signal, e, f, g... Irradiation light , e', f'', g
...Reflected light, h...Irradiation light, i...Image signal.

Claims (1)

[Claims] A binarization circuit that illuminates the soldering part to be inspected from a light source above and converts the grayscale image captured by a camera installed above the soldering part into a binary image, and outputs from the binarization circuit. a window generation circuit that generates an inspection window of a preset shape and size corresponding to the soldered part in the binary image to be inspected; A soldering inspection device comprising: an area measuring circuit that outputs a measured area signal; and a determining circuit that compares the measured area signal with a preset constant value to determine the quality of the soldered part. .