JPH07120405A - Pattern inspection device - Google Patents

Abstract

PURPOSE:To easily inspect the appearance of the wiring pattern of a printed circuit board and the like. CONSTITUTION:A video signal obtained by scanning an objective pattern by means of a photoelectric conversion scanner 1 is binarized by a line thinning circuit 3, the number of steps of a line thinning process is designated based on the reference tolerance of line width by a line thinning process control part 4 so as to perform the line thinning, and thin line images for detecting a thinning defect part and a thickening defect part are obtained. The thine line image for detecting thinning defect is masked with a line thinning part detecting 3X3 mask at a thinning defect part extracting part 7 so as to extract the part of line width '1' as a line thinning defect part, meanwhile, the thin line image for detecting thickening defect is masked with a line thickening part detecting 3X3 mask at a thickening defect part extracting part 8 so as to extract the part of line width over '2' as a line thickening defect part. Finally the positions are computed from the extracted data of the line thinning part and the line thickening part by a result output part 9, and the defect position data is output as a result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection device, and more particularly, to a pattern inspection device for detecting line width thinning and line width thickening defects in a visual inspection of a wiring pattern on a printed circuit board or the like.

[0002]

2. Description of the Related Art Conventionally, for example, "Printed Circuit Board Inspection Using Radial Matching", Journal of Precision Engineering, Vo1.
56, No. 8, pp30-33, 1990, there is a pattern inspection device using a dedicated length measuring sensor and a pattern code.

A conventional pattern inspection apparatus will be briefly described below with reference to the drawings.

FIG. 11 is an explanatory diagram for explaining an inspection method of a pattern inspection apparatus using the above-described length measuring sensor. FIG. 11 shows a length measuring sensor, which is composed of 16 length measuring pixels 102 extending radially with respect to the inspection center 101. Each measuring pixel 102 is the inspection center 10
A symmetrical pattern of the length-measuring pixels 102 with respect to 1 is applied as a target pattern, and the data measured by each length-measuring pixel 102 is coded with the length and symmetry of the length-measuring pixel as elements. Then, the coded data is compared with a previously created coding dictionary to determine whether the code of the target pattern is a point of a normal pattern or a point of a defective pattern.

12 (a), 12 (b) and 12 (c) are schematic views showing an example of coding determination by the length measuring sensor. 12
(A) is a normal pattern, (b) is a line thinning defect. In this case, comparing with the normal pattern,
The length-measuring pixel pairs 103 in the vertical (90 °) direction of the pattern are the same, but the symmetry of the length-measuring pixel pair 104 in the left-right (0 °) direction is conserved, but the length becomes short, and the diagonal (45
The pixel pair 105 in the () direction is asymmetric. Meanwhile (c)
In the case of a line thick defect, compared with a normal pattern, the vertical (90 °) direction and the diagonal (45 °) direction are equal to the normal pattern, but the left and right (0 °) directions are asymmetric.

[0006]

In the above-described conventional pattern inspection apparatus, the pattern state at the inspection center is coded by using the lengthwise extending sensor, and the defect is detected by comparing with the dictionary code created in advance. Therefore, there is a problem that complicated processing such as coding must be executed and that strict dictionary code must be created for complicated patterns without omission.

[0007]

The pattern inspection apparatus of the present invention scans a target wiring pattern and outputs a video signal corresponding to the reflected light, and a video signal from the photoelectric conversion scanner. A binarization circuit for binarizing a binary image signal, a thinning circuit for sequentially performing thin line processing on binary image data obtained by the binarizing circuit to generate thin line image data, and a thin line of the thinning circuit. A fine line processing control unit that controls the number of processing steps based on a line width reference tolerance to generate fine line image data for detecting a thin line defect and thin line image data for detecting a thick line defect, and the fine line controlled by the fine line processing control unit. Thin-line defect image memory for storing thin defect detection image data generated in the thinning circuit, and thin line defect memory generated in the thinning circuit controlled by the thin line processing control unit A defect detecting fine line image memory thickening and stores the image data, the thinning defect detecting fine line image picture data in the memory is read this for the line thinning section detects 3
A thin defect portion detection unit that extracts a portion having a line width of 1 pixel or more detected by applying a × 3 mask as a thin line defect portion, and image data of the thick defect detecting thin line image memory is read, and line thick It is configured to include a thick defect portion detection unit that extracts a portion having a line width of 2 pixels or more detected by applying the portion detection 3 × 3 mask as a line thick defect portion.

The pattern inspection apparatus of the present invention scans a target wiring pattern and outputs a video signal corresponding to the reflected light thereof, and a video signal from the photoelectric conversion scanner into a binary image signal. A binarization circuit for binarizing, a thinning circuit for subjecting the binarized image data obtained by the binarization circuit to thin line image processing to generate thin line image data having a line width of 1 pixel, and the thinning circuit A first line width enlarging circuit for reconstructing a thin line width pattern which is a lower limit line width pattern serving as a reference for line width thinning determination by enlarging the thin line image data A second line width enlarging circuit that reconstructs a thick line width pattern that is an upper limit line width pattern for line width thickening determination by enlarging the generated thin line image data; Binarization circuit A thin portion extraction circuit for extracting a portion protruding from the obtained binary image as a line thinning portion, and a portion where the binary image obtained from the binarization circuit exceeds the thick line width pattern And a thick portion extraction circuit for extracting as.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration and processing flow of an embodiment of the present invention. The operation of this embodiment will be described below with reference to the flow of FIG.

A video signal d obtained by scanning a wiring pattern to be inspected by the photoelectric conversion scanner 1 is a binarization circuit 2, and the pattern portion has a value of "1" and the other portions have a value of "0". The binary image data e binarized is obtained.

Next, in the thinning circuit 3, the thin line processing control section 4 performs thin line processing of the number of fine line processing steps designated based on the line width reference tolerance. First, the thin line processing control unit 4 sets the line width pattern matching the lower limit of the line width tolerance to the line width "1" until the pattern having the line width matching the upper limit of the line width reference tolerance is set to the line width "1". The stage number setting data f1 and f2, which respectively instruct the number of stages of fine line processing up to 1 ”, are set.
In the thinning circuit 3, when the number of thin line processing steps first reaches the established number of steps f1, the thin line image data g at that time is stored in the thin line image memory 5 for thinning defect detection. The processing is terminated at the point of, and the thin line image data h at that time is stored in the thick line defect detecting thin line image memory 6. Each thin line image data is a binary image in which the pattern portion is "1" and the others are "0".

FIG. 2 and FIG. 3 are schematic diagrams showing an operation example of the binarization circuit 2 and the thinning circuit 3.

FIGS. 2A and 3A show a binary image 10 based on the basic binary image data e, in which a thin line portion a and a thick line portion b are present, respectively. This 2
A thin line image 11 of thin line defect detecting thin line image data g and a thin line image 12 of thick portion detecting thin line image data h obtained by performing thin line processing on the value image 10 by the thin line processing control section 4 by the thin line thinning circuit 3. 2 (b) and FIG. 3 (b). This corresponds to the case where the thin line portion a and the thick line portion b exist, respectively.

A characteristic feature here is that, in the fine line image 11 for detecting a thin defect portion, the line width of the fine line image 11 is "2" or more in the normal pattern line width portion, but the line width reference tolerance. This means that the thin line image has a line width of "1" in the thin defect portion a having a line width smaller than the lower limit value of. In one of the thick line defect detection thin line images 12, the line width of the thin line image 12 is “1” in the normal pattern line width portion, but the line width becomes thicker than the upper limit of the line width reference tolerance. This means that the line width of the thin line image becomes "2" or more in the defective portion b. The thin defect detecting unit 7 and the thick defect detecting unit 8 that follow extract the line thin defect and the line thick defect, respectively, using the features described above.

Next, the thin defect portion extracting unit 7 reads the thin line image data o of the thin defect detecting thin line image memory 5 and applies a line thin portion detecting 3 × 3 mask to the thin defect image extraction to extract the thin defect portion. Be seen. On the other hand, in parallel with this, the thick defect portion extraction unit 8 reads the thin line image data p of the thin line image memory 6 for detecting the thick defect and applies a line thick portion detection 3 × 3 mask to this to extract the thick defect portion. Be seen.

4 and 5 are schematic diagrams showing the processing operations of the thin defect portion extraction unit 7 and the thick defect portion extraction unit.

FIG. 4A shows a line thinning portion detection 3 × 3 mask 13 applied to the thin line image data 11 for thinning defect detection, and FIG.
4A is an explanatory diagram of a line thickening detection 3 × 3 mask 14 applied to the thin line defect detection thin line image data 12, and FIG. 4B is a line width “1” extracted by the line thinning portion detection 3 × 3 mask 13. ”
5B is an explanatory diagram of a thick defect portion having a line width of “2” or more extracted by the line thick portion detection 3 × 3 mask 14.

In the thin defect portion extraction unit 7, the thin line portion 3 under the following conditions is detected for all the pattern portions "1" of the thin line image 11 of the read thin line image data for detecting thin line defect portion 3x.
3 The mask 13 is applied and the line narrowing portion 15 having the line width “1” is extracted and sent to the result output unit 9 as the line thinning portion data q.

Condition of line width "1" -When there are two or more groups of "0" in both pixel pairs facing each other in the 3x3 mask, on the other hand, the thick defect part extraction section 8 detects the read line thick defect part. All the pattern portions "1" of the thin line image 12 of the thin line image data p for application are subjected to the line thick portion detection 3 × 3 mask 14 under the following conditions to extract the line thick portion 16 having the line width "2" or more. Is sent to the result output unit 9 as the line thick portion data r.

Condition for line width of "2" or more: Within 3 × 3 mask, when the number of pairs of pixel pairs facing each other is "1" or less, finally, in the result output unit 9, the thin defect extracting unit is used. 7 and the thin line defect portion extraction unit 8 respectively read the thin line portion data q and the thick line portion data r, calculate the central position of each defective portion in the vicinity, and output this as the defective position data s. To do.

FIG. 6 is a block diagram showing the structure and flow of processing in another embodiment of the present invention. The operation of this embodiment will be described below with reference to the flow of FIG.

The video signal D obtained by scanning the wiring pattern to be inspected by the photoelectric conversion scanner 21 is a binary circuit 22, and the pattern portion has a value of "1" and the other portions have a value of "0". Binary image data E is obtained. This binary image data E is used in the next thinning circuit 23, and the thin portion extracting circuit 26 and the thick portion extracting circuit 27 which will be described later.

Next, in the thinning circuit 23, the thin line image data E obtained by the binarizing circuit 22 is subjected to thin line processing to obtain thin line image data F in which the line width of the pattern portion is "1" in the number of pixels. . This thin line image data F is sent to the next line width expansion circuit 24 and line width expansion circuit 25. 7 and 8 are 2
FIG. 7 is a schematic diagram showing operations of the binarization circuit 22 and the thinning circuit 23.

FIG. 7A and FIG. 8A are basic 2
This is a case where a binary image 29 based on the value image data E is shown, and a line thin portion R and a line thick portion S are present, respectively. Thin line images 30 based on the thin line image data F obtained by subjecting the binary image 29 to the thin line processing by the thin line circuit 23 are shown in FIGS. 7 (b) and 8 (b). Corresponding to the case where the thin line portion R and the thick line portion S are present, the thin line image 30 becomes the center line corresponding to the skeleton of the pattern.

Next, in the line width enlarging circuit 24 and the line width enlarging circuit 25, the thin line image data F obtained by the thinning circuit 23.
For each thin line image data F, the line width pattern (thin line width pattern) data G of the lower limit value serving as the reference of the line width thinning determination, and the line width pattern of the upper limit value of the line width thickening determination. (Thick line width pattern) Data H is generated. For each line width pattern, the pattern part is "1",
Others are binary images with a value of "0".

9 and 10 are schematic diagrams showing the defect extraction processing operation after the thinning processing in this embodiment.

FIG. 9A shows the thin line image 30 of FIG. 7B.
10A shows an enlarged thin line width pattern 31, and FIG. 10A shows an enlarged thin line width pattern 32 of the thin line image 30 of FIG. 8B (hatched portion). What is characteristic here is that each line width pattern 31 enlarged with respect to the normal pattern is 2
The value image 29 is completely included, and the thick line width pattern 32 is completely included inside the binary image 29. However, when the thin defect portion R is present, the thin line width pattern 31 is formed in that portion. It protrudes from the binary image 29. On the contrary, the thick defect portion S
If there is, the binary image 29 is projected from the thick line width pattern 32 at that portion. Next, the thin portion extraction circuit 26 and the thick portion extraction circuit 27 respectively extract the line thin defect portion and the line thick defect portion using the above-mentioned features.

Next, in the thin defect part extraction circuit 26, the thin line width pattern data G and 2 generated by the line width expansion circuit 24 are generated.
The binary image data E obtained by the binarization circuit 2 is read and the thin defect portion is extracted. At the same time, the thick defect portion extraction circuit 27 reads the thick line width pattern data H generated by the line width expansion circuit 25 and the binary image data E obtained by the binarization circuit 22 to extract the thick defect portion.

The thin defect portion extraction circuit 26 reads the thin line width pattern data G and the binary image data E that have been read, and extracts a thin defect portion from a portion satisfying the following conditions.

(Binary image data E = 0) AND (thin line width pattern data G = 1) In the thick defect portion extraction circuit 27, the following conditions are satisfied.

(Binary image data E = 1) AND (thick line width pattern data H = 0) FIG. 9B shows the thin defect portion T extracted by the thin defect portion extraction circuit 26 as shown in FIG. b) is a fat defect extraction unit 27
The thick defect portion U extracted by is shown.

Finally, the result output unit 28 reads the line thin portion data O and the line thick portion data P obtained from each of the thin portion extracting circuit 26 and the thick portion extracting circuit 27, and for each defective portion in the vicinity. In summary, the center position is calculated and this is output as defect position data Q.

[0034]

As described above, in the pattern inspection apparatus of the present invention, the thinning processing based on the line width reference tolerance and the simple 3 × 3 mask is applied to the image data of the thinning processing result to obtain the thinning defect portion. And by detecting a line thick defect portion, or by detecting a defect by a combination of a thinning process and an enlarging circuit, a complicated coding process using a length measuring sensor like a conventional pattern inspection device, Defects can be accurately detected without the trouble of creating a coded dictionary in advance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration and a flow of processing according to an embodiment of the present invention.

2 (a) is a diagram showing a binarized image 10 in the case where there is a line thinning part a by the binarizing circuit 2 in FIG. 1, and FIG. 2 (b) is FIG.
Thin line image 1 that has been subjected to thinning processing by the thinning circuit 3 in
It is a figure which shows 1.

3A is a diagram showing a binarized image 10 in the case where there is a thick line portion b by the binarizing circuit 2 in FIG. 1, and FIG. 3B is FIG.
Thin line image 1 that has been subjected to thinning processing by the thinning circuit 3 in
It is a figure which shows 2.

4A is a diagram showing a line thinning portion detection 3 × 3 mask 13 used in the thinning defect portion extraction unit 7 in FIG. 1, and FIG. 4B is extracted by the line thinning portion detection 3 × 3 mask 13. It is a figure which shows the thin defect part of line width "1".

5A is a diagram showing a line thick part detection 3 × 3 mask 14 used in the thick defect part extraction unit 8 in FIG. 1, and FIG. 5B is a line width “extracted by the line thick part detection mask 14”. It is a figure which shows the thick defect part of 2 "or more.

FIG. 6 is a block diagram showing a configuration and a processing flow of another embodiment of the present invention.

7A is a diagram showing a binarized image 29 in the case where there is a line narrowing portion R by the binarization circuit 22 in FIG. 6, and FIG. 7B is a thinning process by the thinning circuit 23 in FIG. It is a figure which shows the thin line image 30 which performed.

8A is a diagram showing a binarized image 29 in the case where there is a line thick portion S by the binarization circuit 22 in FIG. 6, and FIG. 8B is a thinning process by the thinning circuit 23 in FIG. It is a figure which shows the thin line image 30 which performed.

9A is a diagram for explaining the operation of the line width expansion circuit 24 in FIG. 6, and FIG. 9B is a diagram for explaining the operation of the thin portion extraction circuit 26.

10A is a diagram for explaining the operation of the line width expansion circuit 25 in FIG. 6, and FIG. 10B is a diagram for explaining the operation of the thick portion extraction circuit 27.

FIG. 11 is a diagram showing a length measuring sensor of a conventional pattern inspection apparatus.

12A and 12B are schematic diagrams of coding determination examples by the length measuring sensor shown in FIG. 11, where FIG. 12A is a normal pattern, FIG. 12B is a thin line defect portion, and FIG. 12C is a thick defect portion.

[Explanation of symbols]

 1, 21 Photoelectric conversion scanner 2, 22 Binarization circuit 3, 23 Thinning circuit 4 Thin line processing control unit 5 Thin line defect detection thin line image memory 6 Thick line defect detection thin line image memory 7 Thin line defect portion extraction unit 8 Thick line defect portion Extraction unit 9 Result output unit 10,29 Binary image 11,30 Thin line defect detection thin line image 12 Thick line defect detection thin line image 13 Line thin line portion detection 3 × 3 mask 14 Line thick line portion detection 3 × 3 mask 15 Line width “ 1 ”line thinning part 16 line width“ 2 ”or more line thickening part 24, 25 line width expanding circuit 26 thinning part extracting circuit 27 thick part extracting circuit 28 result output part 31 thin line width pattern 32 thick line width pattern 101 inspection Center 102 Measuring pixel 103 Vertical (90 °) direction measuring pixel pair 104 Horizontal (0 °) direction measuring pixel pair 105 Oblique (45 °) direction measuring pixel pair d, D Video signal e, E 2 Value image data f1 Step number setting data of thin line image for thin defect detection f2 Step number setting data of thin line image for thin defect detection g Thin line image data for thin defect detection h Thin line image data for thin defect detection o Thin memory image data for thin defect detection p Thin line defect detection thin line image memory data q, O line narrowing part data r, P line thickening part data s defect position data F thin line image data G thin line width pattern data H thick line width pattern data Q defect position data

Claims (2)

[Claims] 1. A photoelectric conversion scanner for scanning a target wiring pattern and outputting a video signal corresponding to the reflected light,
A binarization circuit that binarizes a video signal from the photoelectric conversion scanner into a binary image signal, and a thin line that sequentially performs thin line processing on the binary image data obtained by the binarization circuit to generate thin line image data. A thinning circuit, and a thin line processing control unit that generates thin line image data for detecting a thin line defect and thin line image data for detecting a thick line defect by controlling the number of thin line processing steps of the thinning circuit based on a line width reference tolerance, A thin line thin line image memory for storing thin line defect detection image data generated by the thin line circuit controlled by the thin line process control unit, and a thick line generated by the thin line circuit controlled by the thin line process control unit. A thin line image memory for detecting a thick defect for storing image data for detecting a defect, and image data of the thin line image memory for detecting a thin defect is read, and a thin line portion detection 3 × 3 cell is read. The thin defect portion detecting portion for extracting a portion having a line width of 1 pixel or more, which is detected by multiplying, as a thin line defect portion, and the image data of the thin line image memory for detecting the thick defect is read, and line thick portion detection 3 A pattern inspection apparatus comprising: a thick defect portion detection unit that extracts a portion having a line width of 2 pixels or more detected by applying a × 3 mask as a line thick defect portion. 2. A photoelectric conversion scanner which scans a target wiring pattern and outputs a video signal corresponding to the reflected light,
A binarization circuit that binarizes the video signal from the photoelectric conversion scanner into a binary image signal, and the binarized image data obtained by the binarization circuit is subjected to successive fine line processing to have a line width of 1 pixel. A thinning circuit that generates thin line image data, and resizes the thin line width pattern that is the lower limit line width pattern that is the reference for line width thinning determination by enlarging the thin line image data generated by the thinning circuit. The first line width enlarging circuit to be configured and the thin line image data generated by the thinning circuit are subjected to enlarging processing to reconstruct a thick line width pattern which is a line width pattern of an upper limit value of the line width thickening determination. A second line width enlarging circuit; a thin portion extracting circuit for extracting a portion of the thin line width pattern protruding from the binary image obtained by the binarizing circuit as a line thinning portion; and the binarizing circuit. The obtained binary image is thick Pattern inspection apparatus which comprises a fat portion extracting circuit for extracting a portion protruding from the width pattern as lines thickened portion.