JP2781022B2 - Solder appearance inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering appearance inspection apparatus for imaging a soldered portion on a printed circuit board using a television camera and inspecting a soldering state. It relates to improvement of inspection accuracy.

[Conventional technology]

Fig. 3 shows the technical magazine "OMRON TECHNICS" Vol.28, No.2, p.
FIG. 128 is a configuration diagram showing the conventional soldering appearance inspection device shown in 128. In the figure, 1 is a television camera, 2 'is an illumination light source, 3 is an IC package, 4 is an IC lead, and 5 is a solder bridge.

 Next, the operation will be described.

IC3 lead 4 soldered on a printed wiring board
Is positioned in the field of view of the television camera 1, the illumination light source 2 'irradiates the soldering portion with illumination light, an image is taken by the television camera 1, and the image is stored in an image memory (not shown). You. Thereafter, a frame for inspection is set between the leads 4 of the image by a computer (not shown). If there is a portion brighter than a predetermined threshold value in the frame, it is determined that the solder bridge is abnormal, and the brightness is higher than the threshold value. If there is no part, it is determined that there is no bridge abnormality, that is, normal.

As the illumination light source 2 ', visible light is often used because the illumination state can be easily confirmed with the naked eye. In the above example, a halogen light source is used.

[Problems to be solved by the invention]

The conventional solder appearance inspection apparatus is configured as described above, and it is assumed that the illumination light is strongly reflected from the solder bridge portion 5. However, in the soldering process, in order to improve the joining, It is common to use a solvent, such as pine wood, at the same time, and this solvent may not fully evaporate and may remain on the solder surface. In this case, reflected light of sufficient intensity could not be obtained, and at a slight rate, a bridge defect could be missed.

Also, when trying to avoid the above-described problems by lowering the threshold level of the brightness determined to be a bridge failure,
On the contrary, there has been a problem that a pattern of white silk printed on the printed wiring board is erroneously determined to be a bridge failure to assist a worker's work.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a soldering appearance inspection apparatus capable of stably judging a normal or abnormal soldering state even when a solvent remains in a soldering portion. The purpose is to:

[Means for solving the problem]

The soldering appearance inspection apparatus according to the present invention illuminates the soldered portion with an infrared light as an illumination light source when capturing an image of the soldered portion with a television camera, and prints the soldered portion of the component and the printed portion on the printed wiring board. A normal pattern and an abnormal state of the soldering state are determined from the image of the pattern.

[Action]

In the present invention, since an image is illuminated using infrared light as the illumination light source, the thin film of the soldering solvent is more easily transmitted than in the case where conventional visible light is used, and the printed wiring board is used. It is less likely to be reflected by the material of the white silk print pattern, which is often used for soldering, and the accuracy of checking the soldered part is better than using visible light illumination, or the contrast between the soldered part and the silk printed pattern is larger. As a result, it is possible to more stably determine whether the soldering state is normal or abnormal.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a soldering appearance inspection apparatus according to an embodiment of the present invention, wherein the same reference numerals as those in FIG. 3 denote the same or corresponding parts, 1 denotes a television camera, 2 denotes an infrared light illumination light source, 6
Denotes an image memory for storing an image captured by the television camera 1, 7 denotes an operation determining unit, and 8 denotes a determination result.

Here, it is assumed that a CCD camera which is particularly sensitive to infrared light is used as the television camera 1.

 Next, the operation will be described.

IC3 lead 4 soldered on a printed wiring board
Is positioned in the field of view of the television camera 1, the infrared illumination light source 2 irradiates the soldered portion with infrared illumination light, the image is captured by the television camera 1, and the image is stored in the image memory 6. It is memorized. In this imaging, the illumination light is not visible light but infrared light, so even if the soldering solvent remains in the soldered part, the soldered part is imaged with better contrast than when illuminated with visible light. be able to.

Next, a frame for inspection is set between the respective leads 4 of the image by the calculation determination unit 7, and if there is a portion brighter than a predetermined threshold value in the frame, it is determined that the solder bridge is abnormal and the brightness is higher than the threshold value. If there is no part, it is determined that there is no bridge abnormality, that is, normal.

This operation will be described in more detail with reference to FIG.

In the figure, 10 is infrared illumination light, 10 'is visible illumination light, 11
Is reflected light, 12 is light energy to be absorbed, 20 is a printed wiring board, 21 is a thin film of a solvent for soldering, 22 is solder, and 23 is a silk print pattern.

FIGS. 6A and 6B show a case where the thin film 21 of the soldering solvent is applied to the solder 22 and a case where the solder 22 is illuminated with the infrared light 10 and a case where the solder 22 is illuminated with the visible light 10 ′. FIG. When the illumination is infrared light 10 (Figure (a)), the absorbed light energy 12 is small, and most of the energy passes through the soldering solvent film 21 and reaches the solder 22 surface.
The reflected light 11 is strong, and a large signal can be obtained by imaging with a television camera. On the other hand, when the illumination is visible light 10 '(FIG. 9B), most of the energy 12 is absorbed when passing through the film 21 of the soldering solvent, and only a small amount reaches the surface of the solder 22. The light 11 is also weakened, and when picked up by a television camera, only a considerably weaker signal is obtained as compared with the case where the infrared light 10 is used.

Therefore, the difference in image signal between the case where the soldering solvent film remains and the case where the soldering solvent film does not remain is smaller in the case of illuminating with infrared light than in the case of illuminating with visible light, and the soldering is stable. An image of the attachment can be obtained.

On the other hand, FIGS. 7C and 7D are diagrams respectively showing a case where the silk print pattern is illuminated with infrared light 10 and a case where it is illuminated with visible light 10 ′. When illuminated with infrared light 10 ((c)
(See FIG.), The energy 12 absorbed by the silk-printed material 23 is large, and the reflected light 11 is weak, so that it can be clearly distinguished from the solder surface. On the other hand, when illuminated with visible light 10 '(FIG. 7 (d)), since a large amount of energy is reflected on the surface of the silk-printed material 23, the reflected light 11 becomes strong and is clearly distinguished from the solder surface. Becomes difficult.

Accordingly, silk printing is less erroneously recognized as solder when illuminated with infrared light than when illuminated with visible light.

In the above embodiment, the soldered portion is illuminated obliquely and the image is taken obliquely. However, the installation angles of the television camera 1 and the infrared light irradiating light source 2 are not limited to this. The same effect can be obtained by arranging the light illumination light sources 2 independently at different angles, for example, at angles crossing vertically.

Further, in the above-described embodiment, the case where a bridge abnormality is detected that there is essentially no solder should be described. By changing the algorithm of the operation determination section 7, the soldering appearance inspection apparatus of the present invention can be applied.

〔The invention's effect〕

As described above, according to the soldering appearance inspection apparatus according to the present invention, when imaging the soldered portion with a television camera,
Since the image is illuminated using infrared light as the illumination light source, the soldered part has high brightness even if the solvent remains in the soldered part, and the silk printed pattern is white or low brightness even if it is white. Therefore, it is possible to stably and correctly determine whether the soldering state is normal or abnormal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a soldering appearance inspection apparatus according to an embodiment of the present invention, FIG. 2 (a) is a diagram showing a case of illuminating with infrared light, and FIG. 2 (b) is illuminating with visible light. FIG. 2 (c) shows a case where the silk print pattern is illuminated with infrared light, FIG. 2 (d) shows a case where the silk print pattern is illuminated with visible light, and FIG. FIG. 3 is a configuration diagram showing a conventional soldering appearance inspection apparatus. 1 ... TV camera, 2 ... Infrared light illumination, 3 ... IC, 4
... Lead, 5... Solder bridge, 6... Image memory, 7. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-305238 (JP, A) JP-A-61-293658 (JP, A) JP-A-61-38406 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 H01L 21/64-21/66 G01N 21/84-21/91 B23K 1/00

Claims (1)

(57) [Claims] 1. A soldering appearance inspection device for irradiating a soldering part of a component mounted on a printed wiring board with soldering light, taking an image of the reflected light with a television camera, and inspecting a soldering state. 3. The soldering appearance inspection device according to claim 1, wherein the illumination light is infrared light, and an image of a soldered portion of the component and a printed pattern on the printed wiring board are taken.