JP2536727B2 - Pattern inspection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection apparatus, and in particular, in the inspection of the line width of a wiring pattern on a printed circuit board or the like, a pseudo defect caused by the thinning of a fine land pattern portion deleted by a through hole is eliminated. The present invention relates to a pattern inspection device applicable to a erasing process.

[0002]

2. Description of the Related Art Conventionally, this type of pattern inspection apparatus is disclosed in, for example, Muto, Ando, "Automation of visual inspection of printed circuit board", Mechanical Design, Vol. 29, No. 2, PP 87-96, 1.
There is a method of using a dedicated mask as shown in 985. FIG. 5 is a schematic diagram for explaining a line width inspection method using this conventional inspection mask. With reference to FIG. 5, in this line width inspection method, the pattern 20 to be inspected is measured by a length measurement sensor 21 having eight radially extending sensors M0 to M7. When the central portion of the length measuring sensor 21 is on the pattern 20 to be inspected, the number of pixels of the length measuring sensor 21 until the pattern 20 to be inspected is counted, and the sum of the number of pixels of the opposite length measuring sensors 21 ( M0 pixel number) + (M4 pixel number), (M1 pixel number) + (M5 pixel number), (M2
Number of pixels) + (number of pixels of M6) and (number of pixels of M3)
+ (The number of pixels of M7), when the sum in the predetermined direction exceeds the specified number of pixels, when the maximum pattern width allowable value is exceeded in the direction perpendicular to it, or when the minimum pattern width allowable value is not satisfied, the line width Detect as defective.

[0003]

Since this conventional pattern inspection apparatus inspects the pattern width regardless of the pattern position, the minute land position originally removed from the pattern width inspection is also detected as a pseudo defect. It In order to eliminate these pseudo defects, it is necessary to separately compare the defect position with the minute land position.

[0004]

A pattern inspection apparatus according to the present invention comprises inspection image input means for picking up a wiring pattern to be inspected and outputting an inspection image, and binarizing means for converting the inspection image into a binary image. And an inversion means for outputting an inverted image obtained by inverting the binary image, a thinning means for converting the inverted image into a thin line image, and a line segment connection in which a line having a width of one pixel is generated in the thin line image. Line segment connection point detection means for detecting a point, a circular mask generation means for determining a circular mask area centered on the line segment connection point, a defect detection means for detecting a line width defect position from the binary image, Defect mask means for deleting from the defect when the line width defect position is within the circular mask region.

Further, the pattern inspection apparatus of the present invention comprises an inspection image input means for picking up a wiring pattern to be inspected and outputting an inspection image, a binarization means for converting the inspection image into a binary image, and the binary image. Inverting means for outputting an inverted image obtained by inverting the value image, thinning means for converting the inverted image into a thin line image, and isolated point detecting means for detecting an isolated point represented by one pixel in the thin line image, A circular mask generating means for determining a circular mask area centered on the isolated point; a defect detecting means for detecting a line width defect position from the binary image;
Defect mask means for removing from the defect when the line width defect position is within the circular region.

[0006]

Next, the present invention will be described with reference to the drawings. Referring to FIG. 1, which shows a block diagram of a first embodiment of the present invention, in a pattern inspection apparatus of this embodiment, an inspection image input unit 1 captures a wiring pattern 10 to be inspected and outputs an inspection image 11. The binarization circuit 2 converts the inspection image 11 into a binary image 12 represented by "0" and "1". The inversion circuit 3 inverts the binary image 12 and outputs the inverted image 13 whose background pattern is represented by "1". The thinning circuit 4 converts the inverted image 13 into a thin line image 14 which is reduced by the set pixels. The line segment connection point detection circuit 5 detects a line segment connection point 15 in which a line having a width of one pixel is generated in the thin line image 14. Circular mask generation circuit 5 is line segment connection point 1
A circular mask area 16 centered at 5 is determined. The defect detection circuit 7 detects the position of the thin defect 17 from the binary image 12. The defect mask circuit 8 deletes from the defect when the defect position 17 is in the circular mask region 16,
The external defect is output as defect data 9.

FIG. 2 is a schematic diagram for explaining the operation of the thinning circuit 4 and the subsequent circuits shown in FIG. Referring to FIG. 2 together with FIG. 1, there is a thin defect 17 detected by the normal defect detection circuit 7 in the wiring pattern 10 to be inspected, which is shown by hatching. When the inversion image of the wiring pattern 10 to be inspected is thinned, a line segment connection point 15 is detected in a portion (a position corresponding to a land) surrounded by the pattern of the wiring pattern 10 to be inspected in the thin line image 14. By making the circular mask region 16 centered on this point a non-inspection region, the pseudo defect (thin defect 17) detected in the minute land portion can be eliminated.

Referring to FIG. 3 which is a block diagram showing a second embodiment of the present invention, in the pattern inspection apparatus of this embodiment, an inspection image input section 1, a binarization circuit 2, an inverting circuit 3 and a thinning circuit 4 are provided. The circular mask generation circuit 5, the defect detection circuit 7 and the defect mask circuit 8 have the same functions as in the first embodiment. The isolated point detection circuit 18 detects an isolated point 19 represented by one pixel in the thin line image 14.

FIG. 4 is a schematic diagram for explaining the operation of the thinning circuit 4 and the subsequent circuits shown in FIG. Referring to FIG. 4 together with FIG. 3, the inspected wiring pattern 10 indicated by hatching has a thin defect 17 which is usually detected by the defect detection circuit 7. When the inversion image of the wiring pattern 10 to be inspected is thinned, an isolated point 19 is detected in the thin line image 14 at a portion (a position corresponding to a land) surrounded by the pattern of the wiring pattern 10 to be inspected. By making the circular mask region 16 centered on this point a non-inspection region, the pseudo defect (thin defect 17) detected in the minute land portion can be eliminated.

[0010]

As described above, according to the present invention,
By binarizing, inverting, and thinning the inspected wiring pattern, detecting line segment connection points or isolated points, and removing line width defects within the circular mask area centered on these points from the defects. , The defect at the minute land position which is not usually considered as a line width defect is automatically removed from all the defects to reduce the pseudo defects.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining an operation after the thinning circuit of FIG.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining an operation after the thinning circuit of FIG.

FIG. 5 is a schematic diagram for explaining a conventional example.

[Explanation of symbols]

 1 Inspection Image Input Section 2 Binary Circuit 3 Inversion Circuit 4 Thinning Circuit 5 Line Segment Connection Detection Circuit 6 Circular Mask Generation Circuit 7 Defect Detection Circuit 8 Defect Mask Circuit 9 Defect Data 10 Inspected Wiring Pattern 11 Inspection Image 12 Binary Image 13 Inverted image 14 Thin line image 15 Line segment connection point 16 Circular mask area 17 Thin defect 18 Isolated point detection circuit 19 Isolated point

Claims (2)

(57) [Claims] 1. An inspection image input means for imaging a wiring pattern to be inspected and outputting an inspection image, a binarization means for converting the inspection image into a binary image, and an inverted image obtained by inverting the binary image. A reversing means for outputting the reversing image, a thinning means for converting the reversing image into a thin line image, and a line segment connecting point detecting means for detecting a line segment connecting point in which a line having a width of one pixel is generated in the thin line image, A circular mask generating means for determining a circular mask area centered on the line segment connection point, a defect detecting means for detecting a line width defect position from the binary image, and a line width defect position within the circular mask area. A pattern inspection apparatus, comprising: a defect mask means for removing from a defect in a certain case. 2. An inspection image input means for picking up a wiring pattern to be inspected and outputting an inspection image, a binarization means for converting the inspection image into a binary image, and an inverted image obtained by inverting the binary image. A reversing means for outputting the reversing image, a thinning means for converting the reversing image into a thin line image, an isolated point detecting means for detecting an isolated point represented by one pixel in the thin line image, and a circle centered on the isolated point. A circular mask generating means for determining a mask area, a defect detecting means for detecting a line width defect position from the binary image, and a defect mask means for deleting from the defect when the line width defect position is within the circular area. A pattern inspection device comprising: