JPH0238885B2 - KIBANJONOHAISENPATAANKENSHUTSUHOHOOYOBISONOSOCHI - Google Patents

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 in particular detects defects in which only the upper part of the wiring pattern of a printed circuit board is chipped and short-circuit defects with low light reflectance. The present invention relates to a method and apparatus for detecting wiring patterns on a substrate suitable for detection.

[Background of the invention]

A conventional pattern detection apparatus, as known from Japanese Patent Application No. 56-33909, uses a detector 15 to detect reflected light from the wiring surface 2 of a printed circuit board 1, as shown in FIG. That is, 1 indicates a printed circuit board, and 2 indicates a wiring pattern on the printed circuit board. 11 is a light source;
12 is a lens that converts the light from the light source 11 into parallel light 31. 13 is a semi-transparent mirror; 14 is an optical image 4 reflected from the wiring surface 2 and obtained through the semi-transparent mirror 13;
1 on the detector 15.

However, in the case of this conventional reflected light detection method, as shown in Figs. 1 and 2, shallow scratches and dirt 5 on the surface of the wiring pattern are falsely detected as defects even though they are not defects. There was a problem that the short-circuit defect 6 having a low reflectance could not be detected.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a substrate that can detect short-circuit defects with low light reflectance and defects where only the upper part of the wiring pattern is chipped, without falsely reporting scratches on the wiring pattern as defects. An object of the present invention is to provide a method and device for detecting a wiring pattern.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized by a detection method that uses both a reflected light detection method and a fluorescent light detection method, and takes advantage of each other's strengths. Fluorescence detection detects the pattern image of the part where the wiring pattern is joined to the base material, and reflected light detection detects the pattern image on the top of the wiring pattern, so the pattern dimensions of the two pattern images are different and cannot be combined as is. Therefore, we invented a method in which the pattern image obtained by fluorescence detection is reduced in size and combined with the pattern image obtained by reflected light detection. Furthermore, since the present invention configures the fluorescent light detection method and the reflected light detection method in one detection optical system,
It is characterized by a detection method that uses reflected infrared light. Specifically, the present invention includes: a first light source that irradiates light onto the wiring surface of a printed circuit board or ceramic substrate; a first detector that detects fluorescence generated from the base material of the printed circuit board or ceramic substrate; a filter for limiting the light from the light source to a wavelength at which fluorescence is likely to be generated; a filter for cutting reflected light from the wiring surface of the printed circuit board or ceramic substrate and transmitting fluorescence generated from the base material; a first imaging lens for forming a wiring pattern image on the detector; and a first imaging lens for directing light from the first light source toward the wiring surface of the printed circuit board to direct fluorescence generated from the base material into the a first semi-transparent mirror that guides the image lens and the detector; a first electric circuit that A/D converts and binarizes the fluorescence detection pattern image; a first memory that stores the same; an electric circuit for reversing black and white of a pattern image stored in a memory and obtaining a reduced pattern, and a second memory for storing this;
Separately, a second light source that irradiates light onto the wiring surface of a printed circuit board or ceramic substrate, a second detector that detects reflected light from the wiring surface of the printed circuit board or ceramic substrate, and a wiring pattern on the detector. A second imaging lens for forming an image, directing light from the second light source toward the wiring surface of the printed circuit board, and directing light reflected from the wiring surface to the second imaging lens and the second imaging lens.
a second semi-transparent mirror that guides the reflected light detection pattern image to the detector, a second electric circuit that A/D converts the reflected light detection pattern image and converts it into a binary value, a third memory that stores this;
means for making the fluorescent light pattern image detected by the second fluorescent light detector and the reflected light pattern image detected by the second reflected light detector be pattern images of the wiring surface at the same location on the printed circuit board; A reduced pattern image of a fluorescent pattern image obtained by fluorescence detection, comprising an electric circuit that masks the contents of the third memory with the contents of the second memory and an electric circuit that extracts defects from the masked pattern image. This pattern detection device detects defects by masking a reflected light detection pattern image at the same location obtained by reflected light detection.

The present invention also provides a pattern detection device characterized in that the light source, imaging lens, and semi-transparent mirror of the fluorescent light detection system and the reflected light detection system are formed by one light source, imaging lens, and semi-transparent mirror. .

Further, the present invention is a pattern detecting device characterized in that an ultra-high pressure mercury lamp is used as a light source for irradiating light onto the wiring surface of a printed circuit board or a ceramic substrate.

The present invention also provides a semi-transparent mirror that directs the light from the light source toward the wiring surface of the printed circuit board and guides the fluorescent light generated from the base material and the reflected light from the wiring surface to the imaging lens and the detector in the pattern detection device. This is a pattern detection device characterized by using a blue-reflecting, red-transmitting dichroic mirror.

Further, the present invention is a pattern detection device characterized in that the fluorescence detection system and the reflected light detection system are integrated into one in the pattern detection device. The present invention also provides a detector for detecting reflected light from a wiring surface due to infrared light leaking from a filter for limiting light from a light source to wavelengths where fluorescence is likely to occur in the pattern detection device. , an infrared reflecting mirror is newly provided to separate fluorescent light and infrared reflected light, guide the fluorescent light to the fluorescent light detection detector, and guide the infrared reflected light to the infrared reflected light detection detector. The feature is that the fluorescent light generated from the base material with light from one light source is detected by the fluorescent light detection detector, and the infrared reflected light from the wiring surface is detected by the infrared reflected light detection detector. This is a pattern detection device. The present invention also provides a pattern detection device characterized in that an infrared transmitting mirror is used as a mirror for separating fluorescent light and infrared reflected light.

The present invention also provides the above pattern detection device,
Spectral sensitivity wavelength range is 500n as a detector for fluorescence detection
This pattern detection device is characterized by using a high-sensitivity detector ranging from m to 700 nm, such as a Sachicon image pickup tube or a Plumbicon image pickup tube.

Further, the present invention provides a pattern detection device characterized in that, in the pattern detection device, a highly sensitive detector having a spectral sensitivity wavelength range of 700 nm to 1100 nm, for example, a silicon vidicon image pickup tube, is used as a detector for detecting infrared reflected light. It is a device.

The present invention also provides a filter, such as a blue filter B370 or
This is a pattern detection device characterized by using B390 or the like.

In addition, the present invention provides the above-mentioned pattern detection device in which the reflected light from the wiring surface due to the strong excitation light for generating fluorescent light from the base material of the printed circuit board or the ceramic board is cut out, and the fluorescent light generated from the base material and the wiring are removed. This pattern detection device is characterized by using a filter having a property of transmitting infrared light reflected from a surface, for example, yellow or orange glass in the range of 480 nm to 560 nm.

The present invention also provides a pattern detecting device characterized in that defects are detected by combining a reduced pattern of a fluorescent pattern image and a reflected light pattern image.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to FIGS. 4 to 22. FIG. 4 shows a fluorescence detection device according to the present invention. In other words, when strong violet light is irradiated onto the wiring surface of a printed circuit board, resist pattern, or ceramic substrate, it has been found that fluorescence is generated from the base material or resist. We found that a negative image can be obtained.

Reference numeral 1 denotes a printed circuit board or a ceramic substrate in which fluorescence is generated from the base material. 2 is a wiring pattern formed of Cu, Cr, or the like. 11 is a high brightness light source;
12 is a condenser lens, 16 is a filter, 16
is a semi-transparent mirror, 18 is a filter, 14 is an imaging lens,
19 is a detector. Therefore, the light 31 emitted from the high-intensity light source 11 passes through the condenser lens 12 and enters the filter 16. The filter 16 is a filter for limiting the wavelength of the light 31 emitted from the high-intensity light source 11 so that fluorescence is likely to be generated from the base material or resist of the printed circuit board or the ceramic substrate 1.
It is generally called blue filter B370, and its maximum transmittance is at a wavelength of 370 nm.
It allows only light with wavelengths between 300nm and 460nm to pass through. The optical path of the light having a limited wavelength is changed by 90 degrees by a semi-transparent mirror 17, and the light is irradiated onto the substrate 1, thereby serving as excitation light for generating fluorescent light from the substrate or resist. Light 42, which is a combination of the fluorescent light generated from the base material or resist and the reflected light from the wiring surface 2, passes through the semi-transparent mirror 17 again and passes through the filter 1.
Enter 8. The filter 18 allows only the fluorescent light 43 outside the limited wavelength range of the excitation light 32 to pass through in order to separate the fluorescent light from the reflected light reflected on the surface of the wiring surface 2 of the substrate 1, and is generally a yellow filter.
It is called Y50 and reflects light with a wavelength of 500 nm or less and transmits light with a wavelength of 500 nm or more. The fluorescent light 43 separated from the reflected light from the wiring surface 2 by the filter 18 is imaged on the photoelectric conversion surface of the detector 19 by the imaging lens 14, so that the fluorescent light 43 is separated from the reflected light from the wiring surface 2.
A negative pattern image of the wiring pattern can be obtained. One embodiment of the present invention shown in FIG. 4 functions as a pattern detection device for detecting fluorescent light generated from a printed circuit board, a resist pattern, or a base material or resist of a ceramic substrate. There is no effect of the scratches 5 existing on the wiring pattern 2 shown, and even if the wiring pattern is glossy, it is possible to detect the negative pattern of the wiring pattern without any problem. Furthermore, as shown in FIGS. 1 and 2, the fluorescence emitted from the base material 4 where residual copper 6 with a low reflectance exists on the surface of the base material 4 is blocked, so that the fluorescence in that area is Not detected and therefore detected as defective. However, this fluorescence detection method has a problem in that it cannot detect a defect 7 in which only the upper part of the wiring pattern 2 is chipped. A pattern inspection apparatus that also solves this problem will be specifically explained based on FIGS. 5 to 22.

That is, in FIG. 5, the printed circuit board 1, high-intensity light source 11, condenser lens 12, first filter 16, semi-transparent mirror 17, second filter 18, imaging lens 14, and fluorescence detector 19 are arranged as shown in FIG. Fourth
It has the same configuration as the pattern detection device shown in the figure with the same reference numeral. In FIG. 6, in contrast to the reflected light detector 15 in FIG. 3, an infrared reflected light detector 15' and an infrared reflective mirror 20, which are marked with a dot to indicate that they are particularly sensitive to infrared light, are newly added. It is provided in The light 31 emitted from the high-intensity light source 11 is converted by the first filter 16 into light 32 with a short wavelength that is likely to generate fluorescence in the base material, and the direction is changed by 90 degrees by the semi-transparent mirror 17 to the wiring surface. Irradiate 2. The first filter 16 not only functions as a fluorescence excitation filter, but also has a characteristic of transmitting a small amount of light in the infrared region, such as a blue filter B370 or B390. The semi-transparent mirror 17 is suitably a 45 degree blue reflective red transmitting dichroic mirror which functions to reflect short wavelength light and transmit long wavelength light such as fluorescent light or infrared light. The light 42, which is a combination of the fluorescent light generated from the base material, the strong reflected light with a short wavelength, and the reflected light due to infrared light, is transmitted through the semi-transmissive mirror 17 and becomes the second light.
The intense reflected light with a short wavelength becomes cut light 43 after passing through the filter 18 . Second filter 1
8 is suitably made of yellow colored glass Y50, etc., which efficiently separates excitation light and fluorescent light. Light 43 passing through the imaging lens 14 is split into infrared reflected light 45 and fluorescent light 44 by an infrared reflecting mirror 20. Infrared reflected light 45
is detected by the infrared reflected light detector 15' to obtain a reflected light pattern image, and the fluorescent light 44 is detected by the fluorescent light detector 19 to obtain a pattern image of the fluorescent light.

The figures from FIG. 6 to FIG. 10 are diagrams showing the characteristics of the constituent elements in detail. FIG. 6 shows the spectral transmittance characteristics of the first filter 16, and FIG. 7 shows the characteristics of the second filter.
8 shows the spectral sensitivity characteristics of the fluorescent detector 19, and FIG. 9 shows the spectral transmittance characteristics of the infrared reflecting mirror 20.
Figure 0 shows the spectral sensitivity characteristics of the infrared reflected light detector 15'.

FIG. 11 shows another embodiment of the invention. 11th
In the figure, the configuration other than the infrared transmitting mirror 21 is the same as the configuration in FIG.
The difference is that the positions of 9 and the infrared reflected light detector 15', and the positions of the fluorescent light 44 and the infrared reflected light 45 are swapped with those in FIG. 6, respectively. In addition, since the infrared transmitting mirror 21 in FIG. 11 has the opposite function to the infrared reflecting mirror 20 in FIG. 5, the only difference in its operation is that transmission and reflection are reversed; Since the operation is the same as that shown in FIG. 5, the explanation will be omitted here. FIG. 12 shows the spectral transmittance characteristics of the infrared transmitting mirror 21.

Next, the defect detection principle will be explained using FIG. 13 and subsequent figures. FIG. 13 is a diagram showing the configuration of the defect detection circuit unit. A detection signal 71 of the fluorescent pattern image detected by the fluorescent detector 19 is A/D converted 52 and binarized 53 and stored in the first memory 54 . This first memory 54 is, for example,
This is the configuration shown in FIG. 22 described in No. 98886. FIG. 14 shows a fluorescent pattern image stored in the first memory 54. On the other hand, the detection signal 71' of the reflected light pattern image detected by the infrared reflected light detector 15' is similarly converted to A/D converter 52' and binarized 52'.
3' and stored in the third memory 54'. This third memory 54' also has the structure shown in FIG. 22, which is described in, for example, Japanese Patent Laid-Open No. 48-98886. 1st
FIG. 6 shows an infrared reflected light pattern image stored in the memory 54' of FIG. 3. The fluorescent pattern image stored in the first memory 54 is inverted in black and white by an inversion/reduction pattern forming circuit 55, and then reduced in size to the second image.
is stored in the memory 56 of. However, this second memory 56 can also be omitted as shown in FIG. FIG. 15 shows an inverted and reduced pattern image stored in the second memory 56. third memory 5
The infrared reflected light pattern image stored in the second memory 56 is masked by a masking circuit 57 using the inverted and reduced pattern image stored in the second memory 56 as a masking pattern. This masking circuit 57 can be constructed of a simple AND circuit as shown in FIG. 22, for example. FIG. 17 is a diagram schematically showing the masked state. That is, the area other than the portion representing the wiring pattern of the inverted and reduced pattern image is masked. In the defect extracting means 58, when a portion that is not the wiring pattern of the infrared reflected light pattern image appears in the wiring pattern portion of the inverted and reduced pattern, it is extracted as a defect, and the defect outputting means 59 outputs it. FIG. 18 shows defect extraction means 58
The pattern image of the defect extracted in is shown.

In general, the cross-sectional shape of the wiring pattern on a printed circuit board is a trapezoid in which the width of the part bonded to the base material is longer than the width of the upper part, and the fluorescent pattern image shows the pattern image of the part bonded to the base material. Since the externally reflected light pattern image shows the upper pattern image, the masking effect cannot be performed as it is. Therefore, it is necessary to reduce the size of the fluorescent detection pattern image. An example of the reduced pattern forming circuit 55 is shown in FIG. This figure is a 2-bit reduction figure. Each square square corresponds to a bit of the detection signal 71. The 5 input signals to one AND circuit correspond to 5 squares forming a cross, that is, 5 bits, and are output only when all of these 5 bits of input signals are "1" signals. is set to “1”. A pattern image formed by replacing this output signal with the signal at the center of the cross of the original input signal is a reduced pattern image and is stored in the second memory 56. However, in the case of the circuit configuration shown in FIG. 22, 55a is an inverter that performs inversion. Further, it is assumed that there is no time delay in the reduced pattern forming circuit 55.

FIG. 19 shows another embodiment of the invention.

In FIG. 19, all components represented by the same reference numerals in FIG. 11 have the same functions. Further, since the operation is the same, the explanation will be omitted, and only the configuration different from that in FIG. 12 will be explained. The reduced pattern forming circuit 60 does not perform the inversion of the inverted reduced pattern shown in FIG. 12, except that black and white are reversed. The specific electric circuit is also the same as that shown in FIG. The formed reduced pattern is stored in the second memory 61. Second
FIG. 0 shows a reduced pattern image stored in the second memory 61. FIG. Next, a combining circuit 62 combines the reduced pattern image stored in the second memory 61 and the infrared reflected light pattern image stored in the third memory 54'. FIG. 21 is a diagram schematically showing the state when combined. The defect extracting means 58 extracts as a defect the overlapping portion of the area representing the wiring pattern in the reduced pattern image and the area representing other than the wiring pattern in the infrared reflection pattern image, and outputs it as a defect. In Figure 21, 90 to each other
A portion where diagonal lines in different directions overlap will be output as a defect, and the output result will be the same as the defect pattern image shown in FIG. 18.

〔Effect of the invention〕

As explained above, the present invention provides a pattern that uses both a fluorescence detection method that detects fluorescence generated from the base material of a printed circuit board or a ceramic board, and a reflected light detection method that detects infrared light reflected from a wiring surface. Since this is a detection method, it has the effect of eliminating false alarms due to scratches on the pattern surface and making it possible to detect short-circuit defects with low light reflectance and defects where only the upper part of the wiring pattern is chipped.

[Brief explanation of drawings]

FIG. 1 is a plan view of the printed circuit board. Figure 2 is a cross-sectional view of the printed circuit board, where a is a cross-sectional view taken along the line A-A in Figure 1, b is a cross-sectional view taken along the B-B line, c is a cross-sectional view taken along the C-C line, and Figure 3 is a conventional reflective FIG. 4 is a side view showing a pattern detection device using a photodetection method; FIG. 4 is a side view showing a pattern detection device using a fluorescence detection method according to the present invention; FIG.
The figure is a side view of a pattern detection device showing an embodiment of the present invention, Figures 6 and 7 are diagrams showing the spectral transmittance characteristics of the filter, and Figures 8 and 10 are the spectral sensitivity of the image pickup tube. Diagrams showing characteristics, Figures 9 and 12
11 is a side view of a pattern detection device showing another embodiment of the present invention, and FIG. 13 is a diagram showing a defect detection circuit unit showing another embodiment of the present invention. Block diagram, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18, Fig. 20
19 and 21 are diagrams showing pattern images, and FIG.
This figure is a block diagram of a defect detection circuit unit showing another embodiment of the present invention, and FIG. 22 is an electric circuit diagram showing one embodiment of a memory, a reduced pattern forming circuit, etc. 1...Printed circuit board, 2...Wiring pattern, 4
... Base material, 11 ... High-intensity light source, 12 ... Condenser lens, 13 ... Semi-transmissive, 14 ... Imaging lens, 15 ... Reflected light detector, 15' ... Infrared reflected light detector, 16...first filter, 17...dichroic mirror, 18...second filter,
19... Fluorescence detector, 20... Infrared reflecting mirror,
21... Infrared transmission mirror, 41... Reflected light, 45
...Infrared reflected light, 51,51'...Detector driver, 52,52'...A/D converter, 53,5
3'...Binarization circuit, 54...First memory, 5
4'...Third memory, 55...Inversion reduction pattern forming circuit, 56...Second memory, 57...Masking circuit, 58...Defect extraction means, 59...
Defect output means, 60...reduced pattern forming circuit,
61...Second memory, 62...Synthesizing circuit, 7
1,71'...Detection signal.

Claims (1)

[Scope of Claims] 1. Detecting a fluorescent image generated from a base material, resist, etc. of a substrate having wiring, reducing the optical image of this fluorescent pattern, and detecting the wiring of the substrate at the same location where the fluorescent light was detected. Wiring pattern detection on a substrate, characterized in that defects in the wiring are detected by detecting a reflected light image from a surface and masking the reflected light detection pattern image obtained by this detection with the reduced fluorescent pattern. Method. 2. Fluorescence detection means for detecting a fluorescence image generated from a base material or resist, etc. of a substrate having wiring, a reduction means for reducing a fluorescence detection pattern image detected by the fluorescence detection means, and wiring of the substrate. A reflected light detection means for detecting a reflected light image from a surface, a masking means for masking a reflected light detection pattern image detected by the reflected light detection means with a reduced fluorescence pattern obtained by the reduction means, and the masking. 1. A wiring pattern detection device on a substrate, comprising: defect detection means for detecting defects in wiring from a pattern masked by the means. 3. The wiring pattern detection device on a substrate according to claim 2, wherein the reduction means is equipped with inversion means for inverting black and white of the fluorescent detection pattern.