JPS6061648A - Pattern detector - Google Patents

Abstract

PURPOSE:To enable the detection of a wiring pattern depending on an effective reflected light by providing a filter in front of an image formation lens to cut off fluorescence. CONSTITUTION:The light 31 incident over a wiring pattern 3 from a highly bright light source 11 is reflected thereon while the light 31 passing through a through hole 8 is reflected against a passive reflector 12. The reflected light 42 becomes the mixture of the fluorescence 43 generated from a base material 4, the reflected light from the wiring pattern 3 and the reflected light from the passive reflector 12. Then, fluorescence 43 transmitted with a filter 24 forms an image on the photoelectric conversion surface of a detector 131 with an image formation lens 251 to obtain a negative pattern of the wiring pattern 3 on a printed circuit board 1. On the other hand, the reflected light 44 transmitting with a filter 26 forms an image on the photoelectric conversion plane of a detector 13 with an image formation lens 25 to obtain a positive pattern of the wiring pattern 3. Thus, the residual light with a low reflectance between the wiring patterns 3 can be checked from the negative pattern of the wiring pattern thereby enabling the detection of a nick caused only at the upper portion of the wiring pattern or the like as the positive pattern of the wiring pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pattern detection device for detecting defects in wiring patterns, and is particularly suitable as a detection section of an inspection device for detecting defects in wiring patterns of boolint boards. The present invention relates to a pattern detection device.

[Background of the invention]

As shown in FIG. 1, the conventional pattern detection device includes a high-intensity light source 11 that irradiates light 61 onto the wiring surface 2 of a printed circuit board 1 or a ceramic substrate, a condenser lens 21, a half mirror 23, and the wiring surface 2. It consists of a detector 15 for detecting reflected light 41 from the wiring pattern 6 and an imaging lens 25 for forming a wiring pattern image on the detector 13. reflected light 4
1, the reflected light from the surface of the base material 4 constituting the board is negligibly small, so this is used to detect the wiring pattern. However, if residual copper 6 with low light reflectance exists between the wiring patterns 6 of the printed circuit board 1 shown in FIGS. 2 and 6, it is detected in the same way as the wiring pattern 6 because it is originally a defect in the printed circuit board 1. There was a problem that it was not detected even though it should be detected. Figure 2 is a plan view of an example of a printed circuit board,
FIGS. 6(a) and 6(b) are cross-sectional views taken along line 1-A and line B-33 in FIG. 2, respectively.

Figures 4 (a) and (b) are diagrams showing the output waveforms when scanning along the A-A line and the R-B line, respectively, using the apparatus shown in Figure 1, and the horizontal axis indicates the position. , the vertical axis indicates the voltage photoelectrically converted by the detector 16. Now, Figure 4 (1
)) To explain the detection results using
The voltage v2 indicates the level of the wiring pattern 5, and the voltage v2 indicates the level of the remaining copper 6. Indicates the level of B.

Since the voltage 4 is lower than the threshold level voltage vT, it is detected that the remaining copper 6 does not exist.

The through hole 8 has a higher voltage Vae than the wiring pattern 6.
generate. If there is a chip 5 in the wiring pattern 6,
The signal is also missing there, as shown at A in FIG. 4(a).

Another conventional pattern detection device is as shown in FIG. High brightness light source 11° condenser lens 21. Half Mi7 2' + Imaging lens 251. Detector 13. The configuration is the same as that in FIG. 1, but a filter 22 and a filter 24 are newly provided, and the high-intensity light source 1
The wavelength of light 61 emitted from 1 is limited by a filter 22,
The excitation light 32 illuminates the wiring surface 2, and the light 42, which is a combination of the fluorescent light generated from the profiteer 4 and the reflected light on the wiring surface 2, is transmitted through the filter 24 and becomes light 43, which is detected by the detector 1.
6, it is detected as a negative pattern of the wiring pattern. However, if there is a chip 5 in which only the upper part of the wiring pattern 6 of the printed circuit board 1 shown in FIG. 2 and FIG. There was a problem in that the same V was detected as in a normal wiring pattern even though it should not be.

This will be explained in detail with reference to FIG. 6(a), which shows the detection results obtained by scanning along line A-A in FIG. 2. In FIG. 6, like FIG. 4, the horizontal axis represents the position, and the vertical axis represents the pressure photoelectrically converted by the detector 16. In FIG.

Voltage 5 indicates the level of wiring pattern B, and voltage V6 indicates the level of base material 4. The level of position A of chip 5 is V5
Therefore, it is detected as the wiring pattern 3, and the chip 5 is detected as if it does not exist.

FIG. 6(b) shows the detection results obtained by scanning along the line BB in FIG. 2, and B in the figure corresponds to the remaining copper 6.

As described above, the conventional pattern detection device that detects reflected light incorrectly detects the remaining copper 6 with low light reflectance, and the pattern detection device that detects fluorescent light incorrectly detects the chip 5 that is missing only in the upper part of the wiring pattern. There was a problem.

[Purpose of the invention]

An object of the present invention is to detect defects in wiring patterns accurately by detecting residual copper with low light reflectance between wiring patterns and chips in the upper part of the wiring patterns without missing them. The objective is to provide a "detection device".

[Summary of the invention]

In order to achieve the above object, a pattern detection device according to the present invention includes a light source that irradiates light onto the wiring surface of a printed circuit board or a ceramic substrate, and a light source that limits the light from the light source to a wavelength where fluorescence is likely to occur. A first filter, a reflection plate set so that the light irradiated onto the wiring surface of a printed circuit board or ceramic substrate is reflected through a through hole, and a reflection plate that reflects light reflected from the wiring surface and the reflection plate and the substrate. A means to separate the optical path of the combined fluorescent light emitted from the base material into two, and a means to cut the reflected light from the wiring surface of the printed circuit board or ceramic board, and to cut the reflected light from the wiring surface of the printed circuit board or ceramic board. a second filter that transmits only the fluorescent light; a first detector that detects the light that has passed through the second filter; and a first detector that forms a wiring pattern image on the first detector. 1, and a third filter that cuts fluorescent light generated from the base material and transmits reflected light reflected from the wiring pattern and the reflective plate; A second detector for detecting light, a second imaging lens for forming a wiring pattern image on the second detector, and a signal photoelectrically converted by the first detector to a certain threshold value. So 2
A first comparator for converting the signal into a value, a second comparator for converting the signal photoelectrically converted by the second detector into a binary value at a certain threshold, and a signal output from the first comparator. In a pattern detection device consisting of an OR circuit for calculating the logical sum of the signals output from the second comparator, the first detector detects only the fluorescent light generated from the base material of the printed circuit board or the ceramic substrate. The wiring pattern is detected as a negative pattern, the second detector detects the wiring pattern of the printed circuit board or ceramic board, and the reflected light reflected from the reflector, the wiring pattern is detected as a positive pattern, and the detection code for both is detected. The gist of the invention is to detect defects such as remaining parts and missing parts by adding the numbers.

That is, as a result of research into a pattern detection device that combines a method for detecting reflected light and a method for detecting fluorescent light, the present invention has developed a method for detecting reflected light by adding a new filter in front of the imaging lens. By cutting the fluorescent light,
This was done based on the knowledge of the present inventors that wiring patterns can be detected by detecting reflected light.

The present invention will be described in detail below using examples with reference to the drawings, but these are merely illustrative and various modifications and improvements may be made without going beyond the scope of the present invention. [Embodiment of the Invention] In FIG. 7, printed circuit board 1. High brightness light source 111 condenser lens 21. Filter 22. Half mirror 25
, filter 24. Imaging lens 251. The configuration of the detector 151 is the same as that of the conventional pattern detection apparatus shown in FIG. An imaging lens 25 and a detector 16 are provided. In FIG. 7, light 31 emitted from a high-intensity light source 11 passes through a condenser lens 21 and enters a filter 22. In FIG. The filter 22 is a filter that limits the wavelength of the light 61 emitted from the high-intensity light source 11 to prevent fluorescent light from being generated from the base material 4 of the printed circuit board 1. For example, it limits the wavelength of light 61 from 300 nm to 460 nm. This is generally called a blue filter, which allows light to pass through.

The optical path of the light with the limited wavelength is changed by 90 degrees by the half mirror 26, and the wiring surface 2 of the printed circuit board 1 is irradiated with the light, and the light is directed to the base material 4.
On the other hand, the light incident on the wiring pattern 6 is reflected, and the light passing through the through hole 8 hits the reflection plate 12 and is reflected. Therefore, the light 42 shown in FIG. 7 is a combination of the fluorescent light generated from the base material 4, the reflected light reflected from the wiring pattern 6, and the reflected light reflected from the reflection plate 12. The light path of the light 42 is divided into two by another half mirror 25,
One passes through the filter 24 and the imaging lens 251 to the detector 13 . the other passes through the filter 26 and the imaging lens 25 and enters the detector 16. The filter 24 transmits only the fluorescent light generated from the base material 4, and therefore transmits light other than the limited wavelength range of the excitation light 32.
For example, it reflects light with a wavelength of 500 nm or less, and
It is generally called a yellow filter, which transmits light of m or more. Fluorescent light 43 transmitted through the filter 24
is imaged by the imaging lens 25 on the photoelectric conversion surface of the detector 161, so that a negative pattern of the wiring pattern of the printed circuit board 1 is obtained. The detection results are the same as those shown in FIG. On the other hand, the filter 26 transmits the reflected light reflected from the wiring pattern 3 and the reflected light reflected by the reflector plate, and thus transmits the same light as the limited wavelength range of the excitation light 62, and has the same characteristics as the filter 22. It is something.

Since the reflected light 44 that has passed through the filter 26 is imaged by the imaging lens 25 on the photoelectric conversion surface of the detector 13, a positive pattern of the wiring pattern of the printed circuit board 1 is obtained. The detection result is that the voltage decreases according to the rate at which the amount of light decreases, but
The signal waveform is almost the same as the result shown in FIG.

Detector 13. The spectral sensitivity characteristic is 70 for wavelengths of 500 nm or more.
It is suitable that the wavelength is 0 nm or less, and the spectral sensitivity characteristic of the detector 1 is suitable that the wavelength is 500 nm or less.

Next, the entire operation of detecting everything on the A--A line and the B--B line in FIG. 1 will be explained using the detection circuit of FIG. 8 and the diagram showing signal waveforms of FIG. 9. The video signal 61 output from the detector 13 corresponds to the signal shown in FIG. 4, and the video signal 62 output from the detector 131 corresponds to the signal shown in FIG. These signals are connected to each comparator 5
1 and 511 with the threshold levels vT and VTI, and the digital signal 65,6 ! 64,6
It is output as 41. Here, the digital signal 63°6
4 shows the detection results on line A-A in FIG.
The waveform shown in figure (a)? S3.64 corresponds to the digital signal 63. , 64. shows the detection results on line B-B in FIG. 1, and the waveforms 63, , 6' shown in FIG. 9(b)
h corresponds. The digital signals 63 and 64 are the following 6
The logical sum is taken by the eight circuits, and the waveform 65 shown in FIG. 9(a) becomes the corresponding digital signal 65, and the first
This shows that a chip 5 in which only the upper part of the wiring pattern on line A-A in the figure was chipped could be detected. Furthermore, the digital signals 631 and 641 are similarly ORed by the 6R circuit, and the waveform 651 shown in FIG. This indicates that residual copper 6 has been detected.

〔Effect of the invention〕

As explained above, according to the present invention, there is a function of detecting fluorescent light generated from the base material of a printed circuit board or a ceramic board, and a function of detecting a negative turn of the wiring, and a function of detecting the negative turn of the wiring, and the reflected light reflected from the wiring surface. This device also has the function of detecting negative turns in wiring patterns (because it is a turn detection device, residual copper with low light reflectivity between wiring patterns can be detected as negative turns in wiring patterns). Defects in the wiring pattern can be detected accurately by detecting defects in the upper part of the wiring pattern as positive turns in the wiring pattern.

[Brief explanation of drawings]

FIG. 1 is a side view of a conventional pattern detector W, FIG. 2 is a plan view of the printed circuit board, and FIG. 6 is a cross-sectional view of the printed circuit board. 1, (b) is a cross-sectional view taken along the line B-B in FIG. 1, FIG. A diagram showing the detection results, (b) is B- in Figure 1.
5 is a side view showing another conventional pattern detecting device, FIG. 6 is a diagram showing detection results by another conventional pattern detecting device, and (a) Figure A-A Figure showing the detector on m, V, (1)) is the first
FIG. 7 is a side view showing the pattern detecting device section of an embodiment of the present invention, and FIG. 8 is a diagram showing the configuration of an example of the pattern p normal detection circuit. Circuit diagram shown,
Figure 9 is a waveform diagram for explaining the operation of the detection circuit.
(a) is a diagram showing all the imaginary waveforms of .lambda.-A in FIG. 1, and (b) is a diagram showing the waveform on line B-13 in FIG. 1. 1... Printed circuit board 2... Wiring surface 6... Wiring pattern 4... Al 1... Chip 6... Remaining copper 8... Through hole 11... High brightness light source 12...
Reflector plates 13, 13+...Detector 21...Condenser lens 22...Filters 23, 23. ...half mirror 2
4... Filter 25, 25.・Imaging lens 26・
... Filter 61 ... Light source light 32 ... Excitation light 4
1...Reflected light 42...Fluorescent light 43...Fluorescent light 44 whose wavelength range of excitation light has been cut...
・Reflected light with the fluorescent wavelength range cut 51 , 51 ,
...Comparator 52-OR circuit 61, W2...Video signal 63, 63h64.641, /15.651...
・Digital signal 1 (mouth) 2nd figure home 3 figure 41 kun 5 country 131 th b circular r7 n 1 ? Problem 3 Figure 9

Claims (1)

[Claims] A light source that irradiates light onto the wiring surface of a printed circuit board or ceramic substrate, a first filter that limits the light from the light source to a wavelength that is likely to generate fluorescence, and a first filter that irradiates the wiring surface of the printed circuit board or ceramic substrate. The reflection plate is set so that the light reflected from the wiring surface and the reflection plate passes through the through hole, and the reflected light from the wiring surface and the reflection plate is combined with the fluorescent light generated from the base material that makes up the board. a second filter that cuts reflected light from the wiring surface of the printed circuit board or ceramic board and transmits only the fluorescent light generated from the base material; a first detector for detecting the light transmitted through the second filter; a first imaging lens for forming a wiring pattern image on the first detector; and a first imaging lens for forming a wiring pattern image on the first detector; a sixth filter that cuts light and transmits reflected light reflected from the wiring pattern and the reflective plate; a second detector that detects the light that has passed through the sixth filter; a second imaging lens for forming a wiring pattern image on the second detector;
A first comparator for binarizing the signal photoelectrically converted by the first detector at a certain threshold value, and a first comparator for binarizing the signal photoelectrically converted by the second detector at a certain threshold value. In a pattern detection device comprising a second comparator and a Ql (circuit) for calculating the logical sum of the signal output from the first comparator and the signal output from the second comparator, the first detector A second detector detects only the fluorescent light generated from the base material of the printed circuit board or ceramic board, detects the wiring pattern as a negative pattern, and detects the reflected light reflected from the wiring pattern of the printed circuit board or ceramic board and the reflective plate. A pattern detection device is characterized in that it detects a wiring pattern as a positive pattern, and accurately detects defects such as residual copper and chips by adding up the detection signals of both.