JPS603507A - Wiring pattern detecting device - Google Patents

Abstract

PURPOSE:To detect with high accuracy a wiring pattern without being affected by oxidation, ruggedness, flaws, etc. of a wiring pattern surface by irradiating light to a printed board, converting photoelectrically fluorescence emitted from a specified wiring surface, and generating fluorescence by exciting a base material. CONSTITUTION:Light 32 which has passed through a filter 22 is the excitation light for generating fluorescence to a base material 4 of a printed board 1, and it is reflected by a half mirror 23, and made incident to a wiring surface 2 of the printed board 1 from a roughly vertical direction. The composite light of reflected light of the excitation light and fluorescence generated by the base material 4 is emitted from the wiring surface 2, but this composite light transmits through the half mirror 23, is made incident to a filter 24, and light 42 which has transmitted through the filter 24 forms an image on a photodetector 13 by a lens 25. The light 42 is only the fluorescence generated by the base material 4 and does not contain the excitation light. That is to say, the fluorescence generated by the base material 4 is emitted from the wiring surface 2 by using a wiring pattern 3 on the wiring surface as a mask, and made incident to the photodetector 13. Accordingly, a negative pattern of the wiring pattern forms an image on the photodetector 13, and a negative pattern signal is obtained as its photoelectric converting output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wiring pattern detection device for detecting a wiring pattern of a printed circuit board, and particularly as a detection unit of an inspection device for detecting defects in the wiring pattern of a printed circuit board. The present invention relates to a suitable wiring pattern detection device.

[Background of the invention]

There is a wiring pattern detection device that obtains a positive pattern (positive image) signal of the wiring pattern by illuminating the wiring pattern of a printed circuit board and photoelectrically converting the reflected light from the wiring surface. However, because this device utilizes the difference in reflectance between the surface of the wiring pattern and the surface of the base material of the printed circuit board, it is easily affected by oxidation, unevenness, scratches, etc. on the surface of the wiring pattern. When used to detect minute wiring patterns, there is a problem in that detection errors are likely to occur.

There is also a wiring pattern detection device configured to obtain a negative pattern (negative image) signal of the wiring pattern by illuminating the surface opposite to the wiring surface to be detected and photoelectrically converting the light transmitted to the wiring surface side. This device is not susceptible to the effects of oxidation on the wiring pattern surface like the former device (however, in the case of a printed circuit board with double-sided wiring, it is sensitive to the effects of the wiring pattern on the opposite side of the wiring surface to be detected). Therefore, there is a problem in that signal processing is required to remove the influence.

[Purpose of the invention]

An object of the present invention is to provide a wiring pattern detection device that does not have the above-mentioned problems.

[Summary of the invention]

The present invention excites the base material of the printed circuit board by irradiating the printed circuit board with light to generate fluorescent light, and obtains a negative pattern signal of the wiring pattern by photoelectrically converting the fluorescent light emitted from a specific wiring surface. It is characterized by this.

[Embodiments of the invention]

FIG. 1 is a schematic side view showing one embodiment of the present invention. In this figure, 11 is a high-intensity light source, and light 31 emitted from this source passes through a lens 21 and enters a filter 22.

The light 32 that has passed through this filter n is excitation light for generating fluorescence in the base material 4 of the printed circuit board 1, and is reflected by the half mirror n, and is reflected on the wiring surface 2 of the printed circuit board 1.
is incident from a direction approximately perpendicular to the direction. In this embodiment, filter n
is a so-called blue filter, for example B
, -: When using a 370 proof filter, the excitation light is 320
The wavelength is limited to a range of about 300 nm to about 460 nm.

A composite light of the reflected excitation light and the fluorescent light generated by the base material 4 is emitted from the wiring surface 2, but this composite light passes through the half mirror, enters the filter, and is transmitted through the filter. The emitted light 42 is focused on the photodetector 13 by the lens 5. The filter is what is called a yellow filter. For example, when a Y-50 sharp cut filter is used, only light having a wavelength of about 500 nm or more is transmitted. Therefore, the light 42 transmitted through the filter is transmitted to the base material 4.
This includes only the fluorescent light generated by the light and does not include excitation light. That is, the fluorescent light generated in the base material 4 comes out from the wiring surface 2 using the wiring pattern 3 on the wiring surface 2 as a mask, and enters the photodetector 13. Therefore, the wiring butter y, v*-n-p
<p-y-b, □7.3□. Wow. A negative pattern signal is obtained as the input photoelectric conversion output.

- As an example, assume that a wiring pattern as shown in FIG. 2 is formed on the wiring surface 2 of the printed circuit board 1, and a negative pattern of the line A-A is imaged on the photodetector 13. Note that FIG. 3 is a sectional view taken along line AA in FIG. 2. In this case, a negative pattern signal as shown in FIG. 4 is obtained from the photodetector 13. As is clear from this figure, if the negative pattern signal is binarized at an appropriate threshold level vT, the wiring pattern portion (the portion where the level is less than vT) and the other portion (the portion where the level is 71 or higher) are separated. can be identified.

As described above, since the present invention utilizes the fluorescent light generated from the base material 4 and emitted from the wiring surface 2, it completely eliminates the problems in conventional devices that utilize reflected light from the wiring surface and conventional devices that utilize transmitted light. It can be resolved.

FIG. 5 is a schematic side view showing another embodiment of the present invention.

In this embodiment, the amount of fluorescent light is increased by emitting excitation light from the surface 2' of the printed circuit board 1 opposite to the wiring surface 2.
This is an attempt to improve the signal N of a negative pattern signal, and parts equivalent to those in FIG. 1 are indicated by the same reference numerals.

In FIG. 5, 51 is a high-intensity light source, and the light emitted from it passes through a lens 52, is reflected by two sets of plane mirror O and concave mirror M, and is irradiated onto surface 2'.

Since the substrate 4 is excited by the light irradiated from both the wiring surface 2 and the opposite side surface 2', it generates a larger amount of fluorescent light than in the previous embodiment. Therefore, since the amount of fluorescent light incident on the photodetector 13 increases, a negative pattern signal with a larger amplitude and better contrast than in the previous embodiment can be obtained.

FIG. 6 shows the negative pattern signal obtained for line A--A in FIG. Comparing this figure with Fig. 4, it can be seen that the amplitude of the negative pattern signal increases in this embodiment, and
It is clear that the S/N ratio is improved. It will also be understood that the range in which the threshold levels v and r can be set is expanded, making it easier to set the same level vT.

In this embodiment, the excitation light is irradiated obliquely to the surface 2'. This is anti-magnetic so that even if there is a wiring pattern on the surface 2, the excitation light is not blocked by the wiring pattern and is transmitted through the base material 4 in a negative direction. Therefore, if there is no wiring pattern on the surface 2', the excitation light may be irradiated onto the surface 2 from a substantially perpendicular direction similarly to the wiring surface 2.

〔Effect of the invention〕

As detailed above, the present invention excites the base material to generate fluorescent light and detects the wiring pattern using the fluorescent light. Therefore, it is possible to prevent oxidation, unevenness, scratches, etc. It has many advantages, such as being able to detect wiring patterns with high accuracy without being affected by signal processing, and also being able to detect wiring patterns on printed circuit boards with double-sided wiring without the need for special signal processing. It is something that can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing one embodiment of the present invention, FIG. 2 is a plan view of a printed circuit board, FIG. 3 is a sectional view taken along line A-A in FIG. 2, and FIG. 2, and FIGS. 5 and 6 are schematic side views showing other embodiments of the present invention, and negative pattern signals obtained for line A-A in FIG. 2, respectively. FIG. 3 is a waveform diagram showing a pattern signal. DESCRIPTION OF SYMBOLS 1... Printed circuit board, 2... Wiring surface, Total... Wiring pattern, 4... Base material, 11, 51... High brightness light source, 13... Photodetector, 21, 25, 52・
...Lens, n, 24...Filter, Wings...Half mirror-153 plane mirror, 54...Concave mirror. /″1 Representative Patent Attorney Makoto Suzuki 1..1 , +] Figure 1 Figure 4 □ I Figure 2 2' Figure 3 4/1 -36- Goki

Claims (2)

[Claims] (1) Means for irradiating the printed circuit board with light for exciting the base material of the printed circuit board to generate fluorescence, photoelectric conversion means, and substantially all of the light emitted from a specific wiring surface of the printed circuit board. and means for selecting only the fluorescent light and making it enter the photoelectric conversion means, and obtaining an electrical signal corresponding to the wiring pattern on the wiring surface as a photoelectric conversion output of the photoelectric conversion means. Detection device. (2) The wiring pattern detection device according to claim 1, wherein the light irradiation means irradiates the wiring surface and the opposite side of the printed circuit board with light.