JPS60135807A - Method and apparatus for detecting wiring pattern on substrate - Google Patents

Abstract

PURPOSE:To make it possible to also detect a residual copper shortcircuit fault low in light reflectivity without falsely reporting narrow part in a remaining land caused by the shift of a throught-hole as a fault, by using a reflected light detecting system and a fluorescence detecting system in combination and utilizing mutual advantages of both systems. CONSTITUTION:An infrared reflected ray detector 15 and an infrared ray reflecting mirror 17 are provided other than a fluorescence detector 19 and the light image of the fluorescence pattern detected by the fluorescence detector 19 is sent to a first stage contraction circuit 56 and second contraction and enlargement circuits 59, 60 and a fluorescence pattern subjected to first stage contraction is masked by a contraction/ enlargement fluorescence pattern in a masking circuit 62 while the reflected light detection pattern image at the same place as fluorescence detection is masked by the contraction/enlargement fluorescence pattern in a masking circuit 63 and both masked signals are sent to a fault extraction circuit 66 and exclusive logical sum processing is performed to detect a fault. By this method, the detection of a residual copper shortcircuit fault low in light reflectivity and the delamination fault in the upper layer part of a wiring pattern is enabled.

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 in particular, detects defects in the upper layer of wiring patterns on printed circuit boards and residues with low light reflectance. The present invention relates to a method and apparatus for detecting wiring patterns on a substrate suitable for detecting copper short circuit defects.

[Background of the invention]

A conventional pattern detecting device, 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, and 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 a lens that forms an optical image 41 reflected from the wiring surface 2 and obtained via the semi-transparent mirror 13 on the detector 15.

However, in the case of this conventional reflected light detection method, as shown in Figures 1 and 2, shallow scratches on the surface of the wiring pattern,
There is a problem in that the dirt 5 is falsely detected as a defect even though it is not a defect, and the short circuit defect 6 having a low light reflectance cannot be detected.

[Purpose of the invention]

The purpose of the present invention is to avoid falsely reporting a narrow portion of the remaining land due to through-hole misalignment as a defect.
It is an object of the present invention to provide a method and apparatus for detecting a wiring pattern on a substrate, which can detect residual copper short-circuit defects with low light reflectance and defects in the upper layer of the wiring pattern.

[Summary of the invention]

In order to achieve the above object, the present invention has invented a detection method that uses both a reflected light detection method and a fluorescent light detection method to take advantage of each other's strengths. Since the fluorescence detection image captures the wiring pattern as a silhouette image, through-holes in the lands are detected as erased images. When this fluorescence detection image is reduced until the wiring pattern disappears, and then subjected to a two-step reduction/enlargement process in which it is enlarged by approximately the same amount as the amount of reduction, the resulting image becomes only of the land.

By ANDing this two-stage reduced/enlarged image and the reflected light detection image, a reflected light wiring image of only the wiring pattern can be obtained. 'Similarly, the AN of this two-step reduced/enlarged image and the fluorescence detection image
If D is taken, a fluorescent wiring image of only the wiring pattern can be obtained. The cross-sectional shape of the wiring pattern of the printed circuit board for which the above method of extracting only the wiring pattern was invented is generally trapezoidal due to the etching characteristics. In order to capture the silhouette of the wiring pattern, fluorescence detection detects the bottom of the trapezoid connected to the base material of the wiring pattern as an image. Further, in the reflected light detection, the upper layer of the wiring pattern, that is, the trapezoidal head S is detected as an image. Therefore, the dimensions of the two detection images are slightly different, and the width of the wiring pattern in the fluorescence detection image is wider than that of the reflected light detection image, and since it is not possible to combine both with this IT, the fluorescence detection image is reduced by one step and the reflected light is We invented a method to perform exclusive OR with the detected image.

That is, the present invention includes a 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, and a first detector that irradiates light from the wiring surface of the printed circuit board or ceramic substrate. a second detector for detecting infrared reflected light; a first filter for limiting the light from the light source to a wavelength where fluorescence is likely to occur; and a wiring surface of the printed circuit board or ceramic substrate. A second filter that cuts reflected light due to excitation light from the base material and transmits fluorescent light generated from the base material and infrared reflected light from the wiring surface; an imaging lens; a semi-transparent mirror that directs light from the light source toward the wiring surface of the printed circuit board and guides fluorescent light generated from the base material and infrared reflected light from the wiring surface to the imaging lens and the detector; an infrared reflector for separating fluorescent light and infrared reflected light, a first electrical circuit that A/D converts the fluorescent light detection image and converts it into a binary value, and a first memory that stores the same; A second electric circuit converts the reflected light detection image into λ/D and binarizes it, a second memory stores it, and reduces the wiring pattern of the image stored in the first memory until it disappears. a two-stage reduction circuit; a two-stage enlargement circuit that enlarges the two-stage reduced image obtained by the circuit by an amount of enlargement that is approximately the same as the reduction amount; and a two-stage enlargement circuit that stores the two-stage reduced and enlarged image obtained by the circuit. 3, a one-step reduction circuit that reduces the fluorescence detection image by one step to the same width as the wiring pattern width of the reflected light detection image, and inverts and stores the one-step reduction image obtained by the circuit. a fourth memory that stores images stored in the second memory and a third memory that stores images stored in the second memory;
(AND)g: A masking circuit to take, a fifth memory that stores the reflected light wiring image obtained by the circuit, a stored image in the fourth memory, and a stored image in the third memory. a masking circuit that performs an AND operation, a sixth memory that stores the fluorescent wiring image obtained by the circuit, and an exclusive OR of the image stored in the fifth memory and the image stored in the sixth memory. It has the advantage of being able to detect residual copper defects with low light reflectance in fluorescence detection, the advantage of not falsely reporting through-hole misalignment as a defect, and the advantage of detecting upper layer peeling defects of wiring patterns in reflected light detection. In order to have both the advantage of detection, the reflected light wiring image obtained by masking the reflected light detection image with a two-step reduced and enlarged image of the fluorescent detection image, and the fluorescent light detection using a two-step reduced and enlarged image of the fluorescent detection image. Masking the one-stage reduced image of the image,
This is a wiring pattern detection device on a substrate, characterized in that it is provided with a defect detection unit that synthesizes fluorescent wiring images obtained by the above-described method.

The present invention proposes to use a part of Japanese Patent Application Laid-Open No. 48-98886 as a means for two-stage reduction and enlargement or as a means for one-stage reduction in the wiring pattern detection device on the above-mentioned board. This is a characteristic feature of a wiring pattern detection device on a board.

[Embodiments of the invention]

Embodiment 8 of the present invention will be described in detail below using FIGS. 4 to 22. FIG. 4 shows a fluorescence detection device according to the present invention. In other words, when the wiring surface of a printed circuit board, resist pattern, or ceramic substrate is irradiated with strong violet light, it is found that fluorescence is generated from the base material or resist, and by detecting this, it is possible to detect the wiring pattern that is the target of detection. It was discovered 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-intensity light source 12 is a condenser lens, 16 is a filter, 17 is a semi-transparent mirror, 18 is a filter, 14 is an imaging lens, and 19 is a detector. Therefore, light 31 emitted from the high-intensity light source 11 passes through the condenser lens 12 and enters the filter 16. The filter 16 uses light emitted from the high-intensity light source 11 to easily generate fluorescence from the base material or resist of the printed circuit board or ceramic substrate 1.
This is a filter for limiting 10 wavelengths, and is generally called blue filter B570.The maximum transmittance is at the wavelength of 37Qnm, and the wavelength range from aoonm to 460nm.
It allows only light with a wavelength of m i to pass through. The source of the limited wavelength is changed in its optical path by 90 degrees by a semi-transparent mirror 17 and irradiates the substrate 1, serving as excitation light for generating fluorescence from the substrate or resist. Light 42, which is a combination of the fluorescent light generated from the base material or the resist and the reflected light from the wiring surface 2, passes through the semi-transparent mirror 17 again and enters the filter 18. 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 20 of the substrate 1.
It is generally called a yellow filter Y50, and reflects light with a wavelength of 5QQnm or less, and transmits light with a wavelength of 5QQnm or more. The fluorescent light 43 separated from the reflected light from the wiring surface 2 by the filter 18 is sent to the imaging lens 1.
4, the image is formed on the light beam conversion surface of the detector 190.
A clear 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 fluorescence generated from a printed circuit board, a resist pattern, a base material of a ceramic substrate, or a resist. 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, if residual copper 6 with a low reflectance exists on the surface of the base material 4 as shown in FIGS. 1 and 2, the fluorescence emitted from the base material 4 will be blocked, so the fluorescence in that area will be reduced. Not detected, detected as defective by follower
15KLΦ.

However, in the case of this fluorescence detection method, there is a problem in that it is impossible to detect a defect 7 in which only the upper part of the wiring pattern 2 is chipped. Regarding a pattern inspection apparatus that also solved this problem, in FIG. 5, a printed circuit board 1, a light source 11. A condenser lens 12, a semi-transparent mirror 13, an imaging lens 14, a first filter 16, a second filter 18, and a fluorescence detector 19 have the same configuration as those with the same reference numerals in the conventional pattern detection device shown in FIG. The difference is that an infrared reflecting mirror 17 and an infrared reflected light detector 15 are newly provided. The illumination light 31 emitted from the light source 11 is converted by the first filter 16 into an excitation fL32 with a short wavelength that easily generates fluorescent light of 10 pieces of printed circuit board 4, and its direction is changed by 90 degrees by the semi-transparent mirror 13. The wiring surface 2 is irradiated. The first filter 16 not only functions as a fluorescence excitation filter, but also
A filter that has the characteristic of transmitting a small amount of light in the infrared region.
For example, blue filter B 370 or B 390'J
%.

The semi-transparent mirror 13 is suitably a 4-da blue reflective red transmitting dichroic mirror that reflects short wavelength light and transmits long wavelength light such as fluorescent light or infrared light.

Light 42, which is a combination of the fluorescent light emitted from the base material 4, the reflected light of the strong excitation light with a short wavelength, and the reflected light of the infrared light, passes through the semi-transparent mirror 13 again and passes through the second filter 18. Light 43 where the reflected light of the excitation light with a short wavelength is cut off
become. The second filter 18 is preferably a yellow or orange color filter, such as Y2O, which efficiently separates the reflected excitation light from the fluorescent light and the infrared reflected light. Light 43 passing through the imaging lens 14 is separated into infrared reflected light 45 and fluorescent light 44 by an infrared reflecting mirror 17.

The infrared reflected light 45 is detected by the infrared reflected light detector 15 to obtain a reflected light image, and the fluorescent light 44 is detected by the fluorescent light detector 19 to obtain a fluorescent image.

Next, the principle of defect detection will be explained in detail using FIG. 6 and subsequent figures. FIG. 6 is a diagram showing the configuration of the defect detection unit 20. Detection signal 71 of the fluorescence image detected by the fluorescence detector 19
is A/D converted 52 and binarized 53 and stored in the first memory 54. This first memory 54 has a structure shown in FIG. 16, which is described in, for example, Japanese Patent Laid-Open No. 48-98886.

FIG. 7 shows an example of a fluorescence detection image stored in the first memory 54, with FIG. 1 as a detection pattern. On the other hand, the detection signal 81 of the reflected light image detected by the infrared reflected light detector 15
is A/D converted and binarized 53' and stored in the second memory 55.

FIG. 8 shows an example of the reflected light detection image stored in the second memory 55, with FIG. 1 as a detection pattern τ. The fluorescent image stored in the first memory 54 is sent as an electrical signal 72 to a two-stage reduction circuit 59 and a one-stage reduction circuit 56, respectively. The two-stage reduction circuit 59 uses a part of the pattern reduction circuit disclosed in Japanese Patent Laid-Open No. 48-98886 to reduce the fluorescent image and eliminate the wiring pattern 3.

FIG. 9 shows a fluorescent image after two-stage reduction processing. Subsequently, the electric signal 72 is sent to the two-stage enlarging circuit 6o, and the two-stage enlarging circuit 60 uses a part of the pattern enlarging circuit disclosed in Japanese Patent Application Laid-open No. 48-98886 to enlarge the fluorescent image after the two-stage reducing process. The land 9 is returned to the original size of the fluorescence detection image. The fluorescent image after the two-step reduction/enlargement process is stored in the third memory 61.

Tenthly, a two-stage reduced and enlarged image stored in the third memory 61 is shown. For the one-stage reduction circuit 56, Japanese Patent Application Laid-Open No. 48-9888
A part of the pattern reduction circuit of No. 6 is used to reduce the fluorescent image, and the width dimension of the wiring pattern 30 is matched with the width dimension of the wiring pattern 30 for reflected light detection. Subsequently, the electrical signal 72 is sent through the inverting circuit 57 to the fourth memory 58, where a one-step reduced inverted image is stored.

FIG. 11 shows a one-step reduced and inverted image stored in the fourth memory 58. Electrical signal 73 read from fourth memory 58 and electric signal 7 read from third memory 61
4 is sent to the masking circuit 62 and subjected to AND processing to obtain a fluorescent wiring image of only the wiring pattern 3 with the land 9 erased, which is sent to the fifth memory 64 as an electric signal 75 and stored therein.

FIG. 12 shows a fluorescent wiring image stored in the fifth memory 64. Electrical signal 8 read from second memory 55
3 and the electric signal read from the third memory 61-197
4 is sent to another masking circuit 63, and subjected to AND processing to obtain a reflected light wiring image of only the wiring pattern 3 with land 9 erased, and sent to a sixth memory 65 as an electric signal 85 to be stored.

FIG. 13 shows a reflected light wiring image stored in the sixth memory 65. In the fluorescence detection image of FIG. 12, a residual copper short-circuit defect 6 with low light reflectance is detected, and in the reflected light wiring image of FIG. 13, a peeling defect 7 in the upper layer of the wiring pattern 3 is detected. ing. The electrical signal 76 read from the fifth memory 64 and the electrical signal 86 read from the sixth memory 65
is sent to the next defect extraction circuit 66, which performs exclusive OR processing to extract defects. FIG. 14 shows a defect image extracted by the defect extraction circuit 66.

15 and 16 show the specific circuit configuration shown in FIG. 6. However, in this case, the memory 61 is not necessarily required. Since the inverter 87 is provided at the input of the two-stage enlarging circuit 60, the signal is enlarged in the opposite manner to the reduction.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be obtained.

1. This is a pattern detection device that uses both a fluorescent light detection method that is generated from the base material of a printed circuit board or ceramic board, and a reflected light detection method that detects infrared light reflected from the wiring surface.
It is possible to eliminate false alarms due to through-hole misalignment and detect residual copper short-circuit defects with low light reflectance and defects in which the upper layer of the wiring pattern is peeled off.

[Brief explanation of the drawing]

Figure 1 is a plan view of the printed circuit board, Figure 2 is a cross-sectional view of the printed circuit board, (a) is a cross-sectional view taken along line A-A in Figure 1, (b)
is a BB @ sectional view, and (C) is a CC @ sectional view. FIG. 3 is a side view showing a conventional pattern detection device using a reflected light detection method, FIG. 4 is a side view showing a pattern detector using a fluorescence detection method according to the present invention, and FIG. 5 is a side view showing an embodiment of the present invention. FIG. 6 is a side view of a pattern detection device showing an example; FIG. 6 is a block diagram of a defect detection unit showing an embodiment of the present invention; FIGS.
Figures 9, 10, 11, 12, 13, and 14 show images, and Figures 15 and 16 show the specific circuit configuration shown in Figure 6. FIG. 1... Printed circuit board 3... Wiring pattern 4...
Base material 5...Through hole 9...Land 11...Light source 12...Condenser lens 13...Semi-transparent mirror 14...Imaging lens 15...Infrared reflected light detector 16... First filter 17... Infrared reflecting mirror 18
...Second filter 19...Fluorescence detector 31...
- Illumination light 44... Fluorescent light 45... Infrared reflected light 51.51'... Detector driver 52.52'... A/D converter 53.53'
...Binarization circuit 54...First memory 55...
Second memory 56...1-stage reduction circuit 57...Inversion circuit 58...Fourth memory 59...2-stage reduction circuit 6
0...Two-stage enlargement circuit 61...Third memory 62.
63... Masking circuit 64... Fifth memory 65... Sixth memory 66
...Defect extraction circuit error 1 figure 20 3n 4th country man 50 Law Naoichi 60th O 7th snake 6th mouth 7th color 70th eye 110 Closed/2 Tomoe) No 3 Saeko Erase 74 mouth

Claims (1)

[Claims] 1. Detecting a fluorescent image generated from a base material or resist of a substrate having wiring, reducing the optical image of this fluorescent pattern, and converting the reduced fluorescent pattern to the above-described image. Mask the fluorescent pattern image with a reduced/enlarged fluorescent pattern,
The reflected light image from the wiring surface of the board is detected at the same location as the fluorescent light detection, and the reflected light detection pattern image obtained by the detection of C is masked with the reduced/enlarged fluorescent pattern, and the signal obtained by masking both A method for detecting wiring patterns on a substrate, the method comprising detecting defects in the wiring by comparing the wiring patterns. 2. Fluorescence detection means for detecting fluorescence generated from a base material of a substrate having wiring, a resist, etc.;
a reduction means for reducing the fluorescence detection pattern image detected by the fluorescence detection means; a reduction enlargement means for reducing and enlarging the fluorescence detection pattern image detected from the fluorescence detection means;
A first masking means for masking the reduced fluorescence detection pattern obtained from the reduction means with the reduced enlarged fluorescence detection pattern obtained by the reduction/enlargement means, and reflected light for detecting a reflected light image from the wiring surface of the board. a detection means, a second masking means for masking the reduced/enlarged fluorescent pattern obtained by the reduction/enlargement means of the reflected light detection pattern image detected by the reflected light detection means, and the first masking means; 1. An apparatus for detecting a wiring pattern on a substrate, comprising a defect detection means for detecting a defect in the wiring by comparing the signal obtained by the masking means and the second masking means.