JPS60170707A - Pattern inspecting device - Google Patents

Abstract

PURPOSE:To decide whether the pattern on a scanning line is normal or not only comparing the frequency of inversion of the light-dark signal of the output signal of a light quantity detector with the correct frequency of inversion on the scanning line of the pattern. CONSTITUTION:The frequency of light-dark inversion of every scanning line of the pattern is stored in a set value storage part 13 through a read circuit 12. When a scan is made is photodetector 1, the frequency of light-dark inversion of the 1st scanning line is read out of the set value storage part 13 and through a setting value changeover circuit 15 held in a set value register 14, and the counted value of a counter 11 is reset to an initial value 0. The counter 11 inputs a signal from a phototransistor to count the frequency of the inversion of an on-off signal due to the light-dark inversion of the pattern, and outputs the result to a comparing circuit 16. The comparing circuit 16 compars this counted value with the set value in the set value register 14 corresponding to the 1st scanning line, thereby making a display ''OK'' on a display element 17 when those values are equal to each other.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a black-and-white pattern photographic film original plate for manufacturing printed circuit boards; The present invention relates to a device for inspecting whether or not a person is present.

(Prior art) Scratches on black and white patterns on photographic film for printed circuit board manufacturing, such as pinholes and scratches in the black pattern, and black spots due to dust and bleeding in the white pattern, are formed by etching the copper foil. It is a direct cause of disconnections and short circuits in the printed circuit conductor wiring on the printed circuit board, so it must be completely eliminated. For this reason, inspections are being conducted to detect flaws in such patterns.

Incidentally, conventionally, such pattern inspection has been carried out by thorough visual inspection or by a fully automated method using pattern recognition using a computer. but,
In the case of visual inspection, it requires a large number of personnel, leading to high costs, and there are problems such as omissions due to the large fatigue of the inspection tools.Furthermore, when using a computer, there are problems with inspection accuracy. While it has great advantages,
There is a problem of high equipment costs.

(Objective) It is an object of the present invention to provide a pattern inspection device that can inspect not only photographic film originals for manufacturing printed circuit boards but also general patterns, and that has a simple structure and is easy to use.

(Structure) The present invention includes a photodetector that includes a built-in light amount detector, and a detector that determines the quality of a pattern based on the output signal of the photodetector. The detector includes a counter that inputs the output signal of the light quantity detector and counts the number of times the light/dark signal is reversed, a setting means that maintains the correct number of times of brightness and dark reversal on the scanning line of the pattern, and each of the counter and the setting means. Comparing means for comparing the number of reversals and output means for outputting the comparison results, and each time the photodetector scans the pattern of the object to be inspected, it is determined whether the pattern on the scanning line is normal or not. It is configured to output as follows.

As the light amount detector, a phototransistor, a photodiode, a CCD (charge coupled device), and other various photodetecting elements can be used.

(Embodiment) FIG. 1 shows an embodiment of a photodetector l that scans over a pattern. A case 2 is shaped like a pencil, and a window 4 is opened at the tip of the case to receive light from an object to be inspected, for example, a photographic film 3. The size of the light receiving window 4 is set to be smaller than or equal to the scanning pitch on the object to be inspected. A phototransistor 5 as a photodetector is provided inside the light receiving window 4, and a reset push button 6 is provided on the side wall of the case 2 to prepare for the next scan. 7 is light irradiated from below when the object to be inspected is a transparent body.

FIG. 2 shows an embodiment of the pattern inspection apparatus of the present invention using the photodetector 1 shown in FIG. jO is a detector that determines the pattern inspection result based on the output signal of the photodetector 1, and a counter 11 that counts the number of inversions of the on/off signal caused by the brightness and darkness of the pattern and is reset (R8T) by a reset signal; A reading circuit 12 as a means for setting the number of times of brightness and darkness inversion, a setting value storage section 13.1, a setting value register 14 that holds the number of times of brightness and darkness inversion of one scanning line, and a setting for updating the contents held in the setting value register 14 by a reset signal. Value switching circuit j5, comparison circuit 16 as comparison means
, and a display element 17 as a means for outputting test results.

The present embodiment will now be explained by taking as an example a case where a pattern on a photographic film 20 as shown in FIG. The settings are stored in the setting value storage section 13. Therefore, the setting value storage section 13 stores the photographic film 2.
The number of times the brightness and darkness of the entire pattern of 0 is reversed is stored in association with the position information of the scanning line 21.

When the reset button 6 is pressed during scanning of the photodetector 1, the number of brightness/dark reversals corresponding to the scanning line 21-1 of one opening is called out from the set value storage section 13 and set via the set value switching circuit 15. It is held in the value register 14, and the count value of the counter 11 is reset to the initial value 0.

When the photodetector 1 is to scan the pattern 22, as shown in FIG. What is necessary is to irradiate the light 7 and detect the transmitted light of the photographic film 20 with the phototransistor 5 of the photodetector 1.

When scanning the photodetector 1, scanning in the scanning line 2j direction and pitch feeding in a direction perpendicular to the scanning line direction may be performed by a simple automatic mechanism, or may be performed manually along a guide such as a ruler. .

In this state, when the photodetector 1 is brought into close contact with the photographic film 20 and scanned over the scanning line 21-1 of the first grain, the counter 11
inputs the signal from phototransistor 5 and creates pattern 2.
The number of on/off signal reversals due to the brightness/dark reversal of No. 2 is counted, and the count I-value is outputted to the comparator circuit 16. The comparison circuit 16 uses this count value and the set value register 14.
is compared with the set value corresponding to the scanning line 21-1 of one opening held in the
” is displayed, and if they do not match, rNOTJ is displayed. When the scanning on the scanning line 21-1 of one opening is completed, if the display is roKl, it means that the pattern on that scanning line is normal, and if it is rNOTJ, it means that there is a flaw or the like.

Next, when moving to the scanning on the second scanning line 21-2, when the reset button 6 of the photodetector 1 is pressed, the counter 11 is set to O by the reset signal, and the set value register 14 is set to 0 for the second scanning. The setting value for the number of times of brightness and darkness inversion corresponding to the line 21-2 is updated, so if the photodetector 1 is scanned in the same way as the first line, the display element 17 will be 1 OK.'' or rN
OTJ is displayed. You can repeat the same below.

As an example of a pattern flaw, if a chip 25 is removed as shown in FIG. Since the inverted signal 3o that should have been present in the case of the pattern is missing, the count value of the counter 11 becomes less than the set value and rNOTJ is displayed. Also,
As an example of other pattern flaws, if there is an extra black pattern 26 as shown in FIG. 3, the output signal from the phototransistor 5 will have an extra inverted signal as shown in FIG. 31 is detected, the count value becomes greater than the set value, and "N01" is also displayed.

As another example, a plurality of light intensity detectors such as phototransistors are arranged in the scanning pitch direction (direction perpendicular to the scanning line direction) in the photodetector, and multiple scanning lines are simultaneously scanned in one scan. You may also do so. However, in this case,
In the detector, it is necessary to provide as many counters 11, setting registers 14, comparison circuits 1G, and display elements 17 as there are light quantity detectors.

Furthermore, a plurality of light quantity detectors can be arranged in the scanning direction in the photodetector. In this case, the detector uses counter 11.
and comparison circuits 16 are provided for the number of light intensity detectors, and each light intensity detector is counted separately.If the count value of the number of light/dark inversions does not match the set value even for one light intensity detector, "No TJ" is displayed. In this way, it is possible to obtain the same accuracy with one scan as with multiple scans.

Furthermore, it is also possible to incorporate a light source into the photodetector and to detect the reflected light from the inspected portion using the light amount detector. In this case, it is possible to inspect not only transparent films as exemplified in Figures 3 and 4, but also patterns on opaque objects such as patterns on ordinary paper and copper foil patterns on printed circuit boards themselves. can.

The device of the present invention can not only sequentially scan the photodetector 1 from the topmost scanning line of a pattern, but also scan from a scanning line at an arbitrary position.

In that case, the setting value storage section 13 stores information representing the position of the scanning line and the correct number of brightness/dark inversions for that scanning line. For example, markings are provided for each scanning line or at fixed distances on the edge of the board on which the object to be inspected is placed, or a code signal indicating the position of the scanning line is provided, and the inspection is performed. Before starting the scanning of the scanning line to be performed, the photodetector 1
By counting the marks up to the scanning position or reading the code signal, the set number of brightness and dark inversions corresponding to the scanning line position may be set in the setting value register 14 from the setting value storage unit 13. .

In this case, the reset push button 6 is not necessary.

The apparatus of the present invention is particularly effective when inspecting a repeating pattern on the entire surface, such as a mesh-like inner layer electrode pattern of a multilayer printed circuit board.

The device of the present invention can also be used in conjunction with visual inspection.

In that case, for example, it is sufficient to first perform an inspection using the apparatus of the present invention, and then visually inspect only those scanning lines that are determined to have flaws or the like.

(Effects) The pattern inspection device of the present invention has a simple structure and can be manufactured at low cost. The device of the present invention can be easily operated manually, or even if it is automated, it can be automated using a simple mechanism.

Furthermore, when the inspection using the apparatus of the present invention is used in combination with visual inspection, there are advantages in that the fatigue of the inspector during the visual inspection is reduced, the inspection time is shortened, and the inspection accuracy is improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a photodetector according to an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment using the same photodetector, and FIG. 3 is a plan view showing an example of an object to be inspected. 4 is a side view showing the inspection method, and FIGS. 5(A) and 5(B) are waveform diagrams showing the output signal of the photodetector when the pattern to be inspected has a flaw. l...Photodetector, 5...E1-transistor, 10...Detector, 11...Counter, 14...Setting value register, 16...
Comparison circuit, 17...display element. Patent applicant Shimadzu Corporation Representative Patent attorney Shigeo Noguchi f+! 7 0

Claims (1)

[Claims] (1) A photodetector with a built-in light intensity detector that scans the pattern; a counter that inputs the output signal of the sight detector and counts the number of times the brightness signal is reversed; A pattern inspection characterized by comprising: a setting means for holding the correct number of reversals, a comparison means for comparing each reversal number of the counter and the setting means, and a detector equipped with an output means for outputting the comparison result. Device.