JPS62119443A - Pattern detection - Google Patents

Abstract

PURPOSE:To simplify an optical system while permitting a light source to be placed as close as possible to a printed circuit board, by forming a black line with an opaque member arranged near the surface of the printed circuit board. CONSTITUTION:A transparent glass plate 21 with an end face 21a mirror polished is arranged near the surface of a printed circuit board 1 and irradiated with a parallel light from a longitudinal light source. As a result, light projected on the end face 21a at a specified angle is totally reflected, which forms a linear black line B on the surface of the printed circuit board 1 corresponding to the end face 21a. The reflected light from the black line B is checked to detect a wire pattern. The opaque member for forming a black line can be that with a linear opaque part deposited on a transparent glass plate or a linear opaque member.

Description

[Detailed Description of the Invention] [Summary] The present invention detects a wiring pattern on a printed wiring board using a black line illumination method, and includes a linear opaque member on the surface of the printed wiring board. are placed close to each other and illuminated from above with parallel light to create a shadow on the surface, and this shadow is used as a black line. By doing so, it becomes possible to form a black line with a simple configuration, and it also becomes possible to increase the amount of illumination light.

[Industrial application field]

The present invention relates to a pattern detection method for detecting an opaque wiring pattern on the surface of a printed wiring board using a black line illumination method, and particularly to an improvement in the method for forming the black line.

[Traditional technique]

A conventional pattern detection system using the black line illumination method is shown in FIG. In the figure, a printed wiring board 1 has a wiring pattern formed on a base material 1a using a copper foil 1b. To detect this wiring pattern, first, the light from the light source 2 is irradiated onto the black line mask 3, which has a linear light shielding material 3b provided on the surface of the glass plate 3a, and the transmitted light is passed through the mask imaging lens 4. An image is formed on the surface of a printed wiring board 1 from diagonally above. Then, a black line B corresponding to the light shielding material 3b is formed there. At this time, since the copper foil 1b does not have light diffusing properties, the black line on the copper F61b is maintained as it is, but the black line on the base material 1a is almost erased by the diffused light from the surroundings. Therefore, the reflected light in the vertical direction is imaged on the light detection surface of the line sensor 6 by the reflected light imaging lens 5. Then, the line sensor 6 can detect only the black line on the copper foil 1b, distinguishing it from other parts, so by optically scanning the entire surface of the printed wiring board 1 while moving it in the X and Y directions, the copper foil The entire pattern of 1b can be detected.

[Problems to be Solved by the Invention] In the above conventional method, it is necessary to provide an expensive mask imaging lens 4 between the blank line mask 3 and the printed wiring board 1, so the production cost is extremely high. As a result, the optical system becomes extremely complex. Furthermore, light source 2
must be provided at a considerable distance from the printed wiring board 1, and since the illumination is performed through the mask imaging lens 4, the amount of illumination of the printed wiring board 1 attenuates midway. There are also drawbacks.

SUMMARY OF THE INVENTION In view of the above conventional problems, an object of the present invention is to provide a pattern detection method that can form a black line with a simple configuration and can obtain a large amount of illumination light.

[Means for solving problems]

In order to achieve the above object, the present invention first disposes a linear opaque member close to the surface of the printed wiring board, and then illuminates the printed wiring board with parallel light from above the opaque member. A linear black line is formed on the top.

Therefore, the wiring pattern on the printed wiring board is detected by detecting the reflected light from the black line in the same manner as in the conventional method.

[For production]

When the opaque member is illuminated with parallel light, a linear shadow is formed on the surface of the printed wiring board, and in the present invention, the shadow is used as a blank line. Therefore, the optical system for illumination can have a simple configuration, and the light source can be placed near the printed wiring board.

Note that the above black line remains dark on the wiring pattern as in the past, and becomes brighter in other areas due to the influence of diffused light, so if the reflected light from this surface is detected, the above wiring pattern can be accurately traced. Can be detected.

(Embodiments of the invention) Examples of the invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of the invention.

In the figure, a printed wiring board 1 is the same as that shown in FIG. 4, and has a wiring pattern formed of copper foil 1b on a base material 1a made of resin such as polyimide or epoxy. To detect this wiring pattern, first, a linear opaque portion 12b is formed on one surface of the transparent glass plate 12a.
The glass mask 12 with the above printed wiring board 1
, for example, in close proximity of about 1 to 0,5 +n. The opaque portion 12b may be formed by, for example, depositing an opaque substance such as chromium on the surface of the glass plate 12a.

Next, an opaque portion 1 is placed diagonally above the glass mask 12.
A longitudinal light source 11 is arranged along the longitudinal direction of the printed wiring board 1, and the surface of the printed wiring board 1 is illuminated through the glass mask 12 by outputting parallel light from the light source 11. Then, since the opaque portion 12b does not transmit the parallel light, a linear shadow of the opaque portion 12b is formed diagonally below the opaque portion 12b on the surface of the printed wiring board 1. In this embodiment, the shadow is used as the black line B. Note that since the distance between the printed wiring board 1 and the opaque portion 12b is narrow, a sufficiently dark black line can be obtained even if the parallelism of the illumination light from the light source 11 is somewhat poor.

The black line B is formed as described above, but in this forming process, there is no need to use the mask imaging lens 4 shown in FIG. 4, so the optical system can be configured with a very simple structure. and the light source 11 is printed and distributed.
Since it can be arranged close to t'1, the amount of illumination light can also be very large.

Note that the above blank line B is similar to the conventional one.
On the base material 1a, the light is kept dark, but on the base material 1a, since the light diffusivity is large, diffused light leaks from the surroundings and becomes bright. That is, in the black line B, the top of the copper foil 1b is dark;
The area on the base material 1a becomes bright. Therefore, the reflected light from the black line B is imaged using the reflected light imaging lens 13.

Next, by arranging a line sensor 14 such as a CCD along the black line on the image forming surface, the line sensor 14 can detect the black line on the copper foil 1b while distinguishing it from other parts. Therefore, by performing the above-described detection while moving the printed wiring board 1 in the X and Y directions, the entire wiring pattern formed of the copper foil 1b can be detected.

Next, FIG. 2 shows the main parts of a second embodiment of the present invention. In the figure, a transparent glass plate 21 whose end surface 21a is mirror-polished is placed close to the surface of a printed wiring board 1, and then parallel light is output from a light source 11 as shown in FIG. Then, since the light incident on the end surface 21a at a predetermined angle is totally reflected, the surface of the printed wiring board 1 has the end surface 21a.
A linear black line B corresponding to this is formed.

Thereafter, the wiring pattern can be detected by detecting the reflected light from the black line B in the same manner as in the case of FIG.

Next, FIG. 3 shows a main part of the embodiment of the present invention shown in FIG.

In the figure, a linear opaque member 31 is brought close to the surface of the printed wiring board 1, and a black line B is formed by irradiating the opaque member 31 with parallel light in the same manner as described above. It is something. Thereafter, the wiring pattern can be detected in the same manner as above.

In the first and second embodiments described above, glass was used as the transparent plate, but other materials such as resin may be used as long as it is transparent.

〔Effect of the invention〕

As explained above, according to the present invention, the black line is formed by an opaque member provided close to the surface of the printed wiring board, so the optical system for forming the black line does not require the conventional expensive system. There is no need to provide a lens for mask imaging, and therefore the above optical system can be configured very simply and at low cost. Furthermore, since the light source for illumination can be placed close to the printed wiring board, the illumination light does not attenuate significantly on the way, and very highly efficient illumination can be achieved, and detection accuracy is also improved accordingly.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a first embodiment of the present invention, Fig. 2 is a schematic diagram showing main parts of a second embodiment of the present invention ~ Fig. 3 is a schematic diagram showing a third embodiment of the present invention FIG. 4 is a schematic diagram showing an example of a conventional pattern detection method using a black line illumination method. DESCRIPTION OF SYMBOLS 1... Printed wiring board, 1a... Base material, 1b... Copper foil, 11... Light source, 12... Glass mask, 12a... Glass plate, 12b... Opaque part, 13 ... Lens for reflected light imaging, 14... Line sensor, 21... Glass plate, 21a... End surface, 31... Opaque member, B... Black line. Figure 1 Figure 2 Figure 3 Included Figure 4

Claims (1)

[Claims] 1) A pattern detection method for detecting a wiring pattern on a printed wiring board by a black line illumination method, which comprises: bringing a linear opaque member close to the surface of the printed wiring board, and applying parallel light from above the opaque member. A pattern detection method comprising forming a black line on the printed wiring board by illuminating the printed wiring board. 2) The pattern detection method according to claim 1, wherein the opaque member is a transparent plate provided with a linear opaque section. 3) The pattern detection method according to claim 1, wherein the opaque member is formed by mirror polishing one end surface of a transparent plate, and the parallel light is totally reflected by the end surface.