JPS60135805A - Pattern detecting method and apparatus therefor - Google Patents

Abstract

PURPOSE:To make it possible to detect the wiring pattern formed on a substrate in a good S/N ratio, by generating fluorescence from the phosphor placed on the back side of the substrate by light transmitted through the base material of the substrate and adding fluorescence generated from the base material to the generated fluorescence before detecting the combined fluorescence by a detector. CONSTITUTION:Light 21 from a light source 5 is allowed to irradiate the wiring surface 2 of a printed circuit board 1 through a first filter 7, a translucent mirror 8 and the wiring surface 2 of the printed circuit board 1 and reflected light is generated from the wiring surface 2 while fluorescence is generated from a base material 3. Further, light 23 transmitted through the base material 3 is incident on the phosphor 12 positioned at the under side of a printed circuit board 1 to generate fluorescence 33. The fluorescence 33 transmits the base material 3 of the printed circuit board 1 again to be directed upwardly. This fluorescence 33 is combined with the fluorescence generated from the base material 3 of the printed circuit board 1 to form fluorescence 34 which is, in turn, passed through the translucent mirror 8 and detected by a detector 11 through a second filter 9. Therefore, fluorescence to be detected increases and the S/N ratio of a detection signal can be improved.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a pattern detection device for detecting wiring patterns, and particularly to a pattern detection method for detecting wiring patterns by capturing fluorescence generated from the base material of a printed circuit board. and its apparatus.

[Background of the invention]

A conventional pattern detection device uses a detector to detect a reflected light image from a wiring pattern on a printed circuit board. However, this detection device has a drawback in that it treats wiring patterns that do not originally have defects (for example, dirt, shallow scratches) as defects.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art, and to
An object of the present invention is to provide a pattern detection method and apparatus for detecting a fluorescent pattern with good quality and recognizing a wiring pattern formed on a substrate.

[Summary of the invention]

In order to achieve the above object, the present invention places a phosphor that generates fluorescent light on the underside of a printed circuit board, and generates fluorescent light from the phosphor by light that has passed through the base material of the printed circuit board. The wiring pattern formed on the substrate to be detected is detected by detecting the fluorescent light transmitted through the base material and returned by a detector in addition to the fluorescent light generated from the base material. That is.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

This is a method in which the wiring surface 2 of the printed circuit board 1 shown in FIG. Since the emitted fluorescence is small, it is necessary to select the first filter 7 or the second filter 90 with good spectral transmittance characteristics, or it is necessary to use a light source 5 with a large output.

Therefore, it was constructed as follows. In FIG. 2, a printed circuit board 1, a light source 5, a condenser lens 6, a first filter 7,
The semi-transparent mirror 8, second filter 9, imaging lens 10, and detector 11 have the same configuration as those with the same numbers in the conventional pattern detection device shown in FIG. 1, but a phosphor 12 is newly added. has been done. The light 21 emitted from the light source 5 is changed by the first filter 7 into light 22 having a wavelength that easily generates fluorescence from the printed circuit board 10'#3, and the optical path is changed by the semi-transparent mirror 8, and the light 21 is directed to the wiring surface of the printed circuit board 1. 2. Reflected light is generated in the wiring 2 of the printed circuit board 1, and fluorescent light is generated in the base material 3. To the east, the light 23 transmitted through the base material 3 is irradiated onto the phosphor 12 located under the printed circuit board 1,
Fluorescence 33 is generated. The fluorescent light 33 is again printed on the printed circuit board 1.
The light passes through the base material 3 and heads upward. Therefore, the light 34 is a combination of the reflected light from the wiring surface 2, the fluorescent light generated from the base material 3, and the fluorescent light generated from the phosphor 12 and transmitted through the base material 3. The light 34 passes through the semi-transparent mirror 8 and enters the second filter 9. The second filter 9 cuts off the reflected light and the fluorescent light 3
5 is transmitted, and is imaged by the imaging lens 10 on the imaging plane of the detector 11.

According to this embodiment, in addition to the fluorescent light generated from the printed circuit board 10 and the base material 3, the fluorescent light generated from the fluorescent body 12 and passing through the base material 3 is also detected, so that the fluorescent light to be detected is increase,
This has the effect of improving the S/N of the detection signal.

FIG. 3 shows an embodiment applied to a printed circuit board 1 having a through hole 13. Fluorescent light 33 is generated from the phosphor 12 by the light 24 passing through the through hole 13, and returns through the through hole 13 to become the light 34 in FIG.
The combined light becomes 36.

FIG. 4 shows a pattern image detected by the detector 11 of the printed circuit board 1 having through holes 13. Six through holes 13 are detected in the pattern image of the pad 14. FIG.

According to the embodiment described above, when the printed circuit board 1 has the through hole 13, the fluorescent light 33 is generated from the fluorescent body 12 by the light 24 that has passed through the through hole 13, and the fluorescent light 33 is generated after passing through the through hole 13 and returned. Since the incoming fluorescent light 33 is detected, the through hole 13 can be detected as a pattern image, and the positional deviation between the pad 14 and the through hole 13 or the diameter of the through hole 13 can be measured.

〔Effect of the invention〕

As explained above, according to the present invention, in addition to the fluorescent light generated from the base material 3 of the printed circuit board 1, the fluorescent light generated from the phosphor 12 and passing through the base material 3 is also detected. Since the amount of fluorescent light to be detected can be increased, the S/N ratio of the detection signal can be improved.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a pattern detection device using a fluorescence detection method according to the present invention, FIGS. 2 and 3 are side views showing a pattern detection device according to an embodiment of the present invention, and FIG. 4 is a pattern image. FIG. 1... Printed circuit board 2... Wiring surface 3... Base material
4... Wiring pattern 5... Light source 6... Condenser lens 7... First
Filter 8...Semi-transparent mirror 9...Second filter
10...Illustrated lens 11...Detector 12...
Fluorescent body 13... Through hole 14... Notch 21.2
2, 23, 24... Illumination light 31, 34, 36... Combined light of fluorescent light and reflected light 32.33.35... Fluorescent light Figure 1, Figure 2

Claims (1)

[Claims] 1. A phosphor that generates fluorescent light is placed on the back side of the substrate, and the fluorescent light generated from the phosphor is transmitted through the base material. In addition, a pattern detection method characterized by detecting with a detector and recognizing a wiring pattern formed on a board. 2. The pattern detection method according to claim 1, wherein the base material of the substrate is used as the phosphor. 3. A light source that irradiates light onto the wiring pattern of the printed circuit board, a detector that detects fluorescent light, and a first filter that limits the light from the light source to a wavelength that is likely to generate fluorescent light; a second filter that cuts reflected light from the wiring pattern of the printed circuit board and transmits fluorescent light; an imaging lens that forms a wiring pattern image on the detector;
A semi-transparent mirror that directs the light from the light source to the wiring surface of the printed circuit board and guides the reflected light and fluorescent light from the wiring surface to the imaging lens and detector side, and a semi-transparent mirror located on the back side of the tooling board that A pattern detection device characterized in that it is equipped with a phosphor that generates fluorescence by light transmitted through a material.