JPH0425750A - Solder amount inspecting method - Google Patents

Abstract

PURPOSE:To accurately grasp the amount of solder at a concave soldering part by measuring the movement quantity between two bright points before and after the switching of different-directional illumination light and the mean distance to them from a lead end surface by image processing and determining the amount of solder. CONSTITUTION:An image pickup camera 6 picks up an image of the soldering part 2 together with parts of a lead 3 and a conductive pattern 4 and the optical image in converted into an analog image signal, which is stored in an image memory 8. This photography is performed by using a light source 5a and then a light source 5b and the image including the bright points Ra and Rb formed at different positions is processed by a CPU 9 to determine the mean distance (x) to the bright points Ra and Rb from the movement quantity (d) between the bright points and the end surface of the lead 3, thereby determining the amount Q of solder at the soldering part 2 according to those values and a preset data table. Consequently, accurate determination becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting the amount of solder in a soldered part in the field of image processing.

[Conventional technology]

The patent applicant has proposed a solder inspection method by filing a patent application No. 2-2749. The solder inspection method is to detect the solder formed between the lead end and the conductive pattern by irradiating the surface of the solder by switching irradiation light from different directions. generate a point,
Before and after the illumination light is switched, the shape of the soldered part and the amount of solder are estimated from the moving direction and amount of movement of the two bright spots, and the quality of the soldering is determined.

[Issues with conventional technology]

As long as the soldering part always adheres to the end surface of the lead up to a certain height position, the amount of solder in the shape of the solder can be determined almost accurately by the above method.

However, if the adhesion position of the solder to the end face of the lead changes in the height direction of the lead, that is, in the thickness direction, the difference will depend only on the direction and amount of movement of the bright spot before and after switching the illumination light.
The shape of the solder and the amount of solder cannot be accurately identified, resulting in a decrease in the reliability of the inspection results.

In addition, there is a tendency for concave surfaces to be used rather than convex surfaces as a good surface shape for soldering parts, and due to the soldering conditions, especially the soldering temperature and solder amount supply control, concave-shaped solders tend to be used. There are many shapes of the attached parts.

[Purpose of the invention]

Therefore, it is an object of the present invention to target the six soldered parts on the concave surface, and to make it possible to accurately grasp the amount of solder soldered to the lead end face in the field of drawing and processing, regardless of changes in the soldered part and the adhesion position. There is one thing to do.

[Solution means of the invention and its effects]

In view of the above object, the present invention switches and irradiates illumination light from different directions to the surface U of the soldering part formed between the end of the lead and the At pattern, and the soldering part formed between the end of the lead and the At pattern. While adopting the conventional basic principle of generating a bright spot for each illumination light, the amount of movement of the two bright spots before and after the switching of the statement light, and the amount of movement from the end face of the lead to each bright spot. The average distance is measured in the field of one-shot processing, and the amount of soldering is determined from the measured value and a data table of the amount of solder corresponding to the measured value.

Here, the amount of movement of a bright spot and the amount of soldering for a certain average distance from the end 1 of the lead to each bright spot are compiled in advance as data through theoretical calculations or actual measurements.

According to this solder amount inspection method, even if the adhesion position of the solder on the lead end surface changes in the thickness direction, the solder amount can be accurately detected as long as the surface shape of the solder is concave. can.

〔Example] FIG. 1 shows an overview of an image processing system 1. As shown in FIG.

The soldering part 2 to be inspected is the soldering part 2, which is the soldering part 2 of the inspection target.
A concave surface is formed between the end surface of the board 3 and a conductive pattern 4 such as a circuit board, and a light source 5 is located slightly diagonally above the conductive pattern 4.
By switching between a and 5b, it is irradiated with illumination light in different directions, and a bright spot R is created on the surface for each illumination light.
a and Rb are generated. Note that these two light sources 5a
, 5b can be selectively switched to/:J by a switch 14.

The soldering part 2 is converted from an optical image to an electrical image by an upper imaging camera 6, and is converted from an analog signal to a digital signal by an A-D converter 7, and is stored in an image memory 8. be done.

Image processing is executed by a CPU (central processing unit) 9 connected to a memory 10, a display 11, an input unit 12, and the like. Note that these are placed under synchronization/interrupt control by the control circuit 13.

When the soldering part 2 to be inspected is positioned within the field of view of the imaging camera 6, the imaging camera 6 photographs the soldering part 2 to be inspected together with the leads 3 and part of the conductive pattern 4, and creates an optical image. is converted into an electrical image, and the analog image signal is converted into a digital image signal by the AD converter 7, and then stored in the image memory 8. In the first photographing, the illumination light from the first light fi5a is used, and in the next photographing, the illumination light from the light source 5b is used.

In each photographing process, as shown in Fig. 2, the soldering occurs at different points 1 on the surface of the part 2, so the illumination light is switched from the light source 5a to the light source 5b. The bright spot Ra appears to move to the position of the bright spot Rb. The image memory 8 stores images including these bright spots Ra and Rb.

At the subsequent image processing stage, the CPU 9 executes an image processing program, cuts out only part 2 of the solder to be inspected as a window of, for example, about 40 x 40 (dots), and creates an image using the light source 5b. In addition to identifying the bright spot Ra, the bright spot Rb in the image produced by the light source 5b is identified and its position determined. ,R
The average distance X to b is determined by image processing from the number of dots and the like.

After this, the CPU 9 calculates the soldering for part 2 of the soldering to be inspected from the data table of the measured movement amount d and average distance X and the soldering amount Q preset for each of these values. Determine the quantity Q. Here, the amount of movement d, the average distance
The amount of soldering Q corresponding to 2 is set in advance as a numerical table based on theoretical calculations or experimental data, and is stored in the memory 10 or the like. Therefore, after determining the movement lid and the average distance HX on the image, the CPU 9 refers to these numerical tables and determines the soldering amount Q from the matching position of the corresponding numerical values.

Note that the ridgeline of soldering part 2 is Y as shown in Figure 3.
It can be approximated by a curve of zbe-''.

Further, as shown in FIG. 3, the movement amount d increases as the value of the point with respect to the Y axis decreases. Therefore, the movement amount d and the average distance X are used as elements for determining the above curve.

〔Effect of the invention〕

In the present invention, the form of a soldered part formed by illumination light from different directions is identified from the amount of movement of a bright spot on the part surface and the average distance from the lead end face to each bright spot, and this form is Since the amount of soldering is determined based on
Even if the adhesion position of the solder part changes in the thickness direction of the lead end face, the amount of solder can be determined almost accurately regardless of the change, and the reliability of the solder amount inspection is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the image processing system, FIG. 2 is an enlarged plan view of the soldering section, and FIG. 3 is a graph of a curved line on the surface of the soldering section. Engineering... Image processing system, 2... Soldering part, 3... Lead, 4... Conductive pattern, 5a, 5b... Light source, 6...
・Image camera, 7...A-D converter, 8...Image memory, 9...CPU (central processing unit) 10...Memory, 11...Display, 12...Input crab unit, 1
3...11 jB circuit, 14...switcher. Patent applicant Rozef Technology Co., Ltd.
Patent Attorney Kuni Nakagawa Younger brother Figure 2: Soldering part 3: Lead 4; Conductive patterns 5a, 5b: Light source 6; Imaging camera Figure

Claims (1)

[Claims] Illumination light is switched from different directions and irradiated onto the surface of the soldered part formed between the end of the lead and the conductive pattern, and a bright spot is generated for each illumination light on the surface of the soldered part,
A solder amount inspection method characterized in that the amount of solder is determined from the amount of movement of two bright spots before and after switching the illumination light and the average distance from the end face of the lead to each bright spot.