KR20160102877A - Pattern inspection apparatus and pattern inspection method - Google Patents

Abstract

A coordinate of a center (C2) of an attention hole area (63) indicating one attention hole is acquired on a photographed inspection image of a print substrate having a wire pattern including a land and a line and a hole in pattern inspection. A line direction (A4) in which an attention line connected to an attention land having an attention hole is extended from a viewpoint of the attention land is specified based on reference pattern data indicating the wire pattern. A point on a target edge (631) closest to a position where a line extending from the center of the attention hole area in the line direction and an edge of the attention hole area cross is acquired as a discrimination point (P2a) using a portion which is an edge of the attention hole area and included in a wire pattern area (60) indicating the wire pattern as the target edge in the inspection image. Whether the discrimination point is positioned outside an attention land area (61) indicating the attention land is determined to easily detect loss of a neck by the attention hole.

Description

[0001] DESCRIPTION [0002] PATTERN INSPECTION APPARATUS AND PATTERN INSPECTION METHOD [

The present invention relates to a pattern inspection apparatus and a pattern inspection method for a printed circuit board.

BACKGROUND ART Conventionally, various techniques have been proposed in inspection of wiring patterns and holes (for example, vias and through holes) formed on a printed board. For example, in JP-A-2010-175483 (Document 1), an image of an inspection area is binarized to perform a labeling process on an area other than the pads, and the positional deviation of the through holes Is determined. Japanese Patent Application Laid-open No. H9-203620 (Document 2) discloses a method of detecting an edge of a wiring pattern in image data of a region including a land by using an edge extraction filter as edge image data for each predetermined direction component Decomposed and extracted. Subsequently, a plurality of edge image data are integrated by the hierarchical adaptive filter while the blurring process and the thinning process are performed, and the output value indicating the degree of approximation to the shape corresponding to the line breakage is calculated, .

In Japanese Patent Application Laid-Open No. 4-355352 (Document 3), a binary image of a wiring pattern is divided into a land image corresponding to the land and a line image corresponding to the line. Also, a hall image, which is a binarized image of the hole, is also acquired, and the presence or absence of the neck breakage is determined based on the size of the overlapping portion of the line image and the enlarged hole image obtained by enlarging the hall image. In Japanese Patent Application Laid-Open No. 4-184244 (Document 4), a pattern image representing a wiring pattern and a hole image representing a through hole are obtained based on image data representing a printed substrate, and a thinning process Is performed to obtain a thinned pattern image. Then, the neck break of the wiring pattern is detected from the number of end points of the thinned pattern image in the window including the hall image.

Incidentally, in the documents 1 to 4, since the processing (labeling processing, expansion processing, etc.) based on the luminance value is performed for all the pixels of the image showing the vicinity of the land, the amount of computation is increased. In practice, expensive circuits capable of parallel calculation such as FPGA (field-programmable gate array) and the like are required, and the cost related to inspection of the printed board is increased. In addition, in the wiring pattern, a defect in which a land and a line are partially separated by a hole portion (hereinafter, such a defect and a neck breakage are referred to as " neck defect &Quot;) is also required to be detected.

The present invention is directed to a pattern inspection apparatus for a printed circuit board, and aims at easily detecting neck defects.

The pattern inspection apparatus according to the present invention obtains the coordinates of the center of the target hole area indicating one target hole portion in a wiring pattern including lands and lines and a test image obtained by photographing a printed board on which the hole is formed Based on the reference pattern data indicating the wiring pattern or the inspection line connected to the landmark on which the landmark hole is formed based on the inspection image, A line direction specifying portion that specifies a line direction and a portion included in a wiring pattern region which is the edge of the target hole portion region and which is included in the wiring pattern region as the target edge, A line extending from the center in the line direction and the edge of the target hole area intersect When the discrimination point is located outside the target land area indicating the target land or in the target line area indicating the target line And a neck defect detecting portion for detecting a neck defect due to the above-mentioned target hole portion when the above-mentioned neck hole is located.

According to the present invention, neck defects can be detected easily.

In one preferred form of the present invention, the hole information acquiring section sets, in the inspection image, a plurality of angular directions at constant angular intervals with reference to the center of the target hole section area, A plurality of candidate points which are points on the target edge in the angular direction are obtained, and the above-mentioned point acquisition section obtains one candidate point among the plurality of candidate points as the above-mentioned point.

In this case, more preferably, the pattern inspection apparatus further includes a reference pattern data and reference data including reference hole data indicating coordinates of the center of the hole, Wherein in the wiring pattern indicated by the reference pattern data, the center of the target hole portion indicated by the reference hole portion data is set to be the center of the target land, and each of the plurality of angular directions from the center of the target land The line direction and the radius of the noted land area are obtained by obtaining the distance to the edge of the wiring pattern in the line direction. It is preferable that the neck defect detection unit is configured to calculate the distance between the center of the noted land area and the plate star point with the center of the noted hole area indicated by the reference hole portion data as the center of the noted land area, By comparing the radius of the area, the neck defect may be detected.

In the pattern inspecting apparatus for obtaining the plurality of candidate points, the hole information acquiring section acquires a plurality of candidate points in the circumferential direction, It is possible to detect a land break due to the target hole portion when there is a candidate direction group that is a set of candidate directions. More preferably, the pattern inspection apparatus is characterized in that the discrimination point in the target hole portion in which the neck defect is detected is sandwiched between two groups of non-candidate direction discontinuous in the circumferential direction, and the two non- And a neck break detecting portion for detecting a break of a neck caused by the target hole portion when the angle formed by the representative direction of the direction group is equal to or less than a predetermined angle.

In another preferred form of the present invention, in the inspection image, when the angle formed by the direction from the center of the noted land area to the center of the target hole area and the line direction is a predetermined angle or more, The star point acquisition unit does not acquire the above-mentioned star point for the target hole portion.

The present invention is also for a pattern inspection method of a printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

According to the present invention, neck defects can be detected easily.

1 is a diagram showing a configuration of a pattern inspection apparatus.
2 is a diagram showing a configuration of a computer.
3 is a block diagram showing a functional configuration of the pattern inspection apparatus.
4 is a view showing a reference image.
5 is a diagram showing an inspection image.
6 is a view showing a check image.
Fig. 7 is a diagram showing an inspection image. Fig.
Fig. 8 is a diagram showing an inspection image. Fig.
9A is a view showing a flow of a process in which a pattern inspection apparatus inspects a printed board.
Fig. 9B is a view showing a flow of processing for inspecting a printed board by the pattern inspecting apparatus. Fig.
10 is a diagram showing a check image.
11 is a diagram showing an inspection image.
12 is a diagram showing a check image.
13 is a diagram showing a check image.
14A is a diagram showing a reference image.
14B is a diagram showing a reference image.
14C is a diagram showing a reference image.
15A is a diagram showing a check image.
Fig. 15B is a diagram showing an inspection image. Fig.
16A is a diagram showing an inspection image.
16B is a diagram showing a check image.
16C is a diagram showing a check image.
16D is a diagram showing a check image.
17A is a diagram showing a check image.
17B is a view showing a check image.
Fig. 17C is a diagram showing an inspection image. Fig.
17D is a diagram showing a check image.
18A is a diagram showing a check image.
Fig. 18B is a diagram showing an inspection image. Fig.
18C is a diagram showing a check image.
Fig. 19 is a diagram showing an inspection image. Fig.
20 is a diagram showing a test image.
21A is a diagram showing an inspection image.
Fig. 21B is a diagram showing an inspection image. Fig.

1 is a diagram showing a configuration of a pattern inspection apparatus 1 according to one embodiment of the present invention. The pattern inspecting apparatus 1 inspects the appearance of a printed circuit board 9 (also called a printed wiring board) before electronic components are mounted, for example. On the printed board 9, wiring patterns including lands and lines, and hole portions (for example, through holes and vias) are formed. In the present embodiment, a multilayer board in which a plurality of boards on which wiring patterns are formed is a printed board 9 to be inspected. However, even if each board before being superimposed as a multilayer substrate becomes a printed board 9 to be inspected do.

The pattern inspection apparatus 1 includes a main body 2 for capturing a printed substrate 9 and a computer 5 for controlling the overall operation of the pattern inspection apparatus 1 and realizing an operation unit and the like to be described later, Respectively. The apparatus main body 2 includes an image pickup section 21 for picking up an image of a multi-gradation image of the printed board 9, a stage 22 for holding the printed board 9, And a stage driving unit 23 for relatively moving the stage 22 with respect to the stage 21. The imaging section 21 includes an illumination section 211 that emits illumination light, an optical system 212 in which light from the printed substrate 9 is incident to the printed substrate 9 at the same time as the illumination light is incident on the optical system 212 And an image pickup device 213 for converting the image of the printed board 9 formed by the image pickup device 213 into an electric signal.

The stage driving unit 23 is constituted by a ball screw, a guide rail, a motor, and the like. The computer 5 controls the stage driving section 23 and the imaging section 21 to pick up a predetermined area on the printed board 9. [ Another mechanism for relatively moving the imaging unit 21 with respect to the printed board 9 may be provided instead of the stage driving unit 23. [

Fig. 2 is a diagram showing a configuration of the computer 5. Fig. The computer 5 has a general computer system configuration including a CPU 51 for carrying out various kinds of calculation processing, a ROM 52 for storing a basic program, and a RAM 53 for storing various kinds of information. The computer 5 includes a fixed disk 54 for storing information, a display 55 for displaying various information such as an image, a keyboard 56a for receiving an input from an operator, and a mouse 56b A reading device 57 for reading information from a computer-readable recording medium 8 such as an optical disk, a magnetic disk or a magneto-optical disk, And a communication unit 58 for transmitting and receiving signals with other configurations.

In the computer 5, the program 80 is read out from the recording medium 8 via the reading device 57 in advance and stored in the fixed disk 54. [ The CPU 51 executes calculation processing using the RAM 53 or the fixed disk 54 in accordance with the program 80. [

Fig. 3 is a block diagram showing the functional structure of the pattern inspection apparatus 1. As shown in Fig. 3, the function configuration realized by the CPU 51, the ROM 52, the RAM 53, the fixed disk 54, etc. of the computer 5 is enclosed by a dashed rectangle with a reference numeral 5. The computer 5 has an arithmetic unit 41 and a storage unit 49. The calculation unit 41 has a hole information acquisition unit 411, a line direction specification unit 412, an evaluation point acquisition unit 413, a neck defect detection unit 414 and a neck interruption detection unit 415. Although not shown, the overall control unit for controlling the operation of each functional configuration is realized by the arithmetic unit 41 as well. Details of the functions realized by these configurations will be described later. These functions may be constructed by a dedicated electric circuit, or a dedicated electric circuit may be partially used.

The storage unit 49 stores reference data 491 prepared in advance. Reference data 491 includes reference image data 492 and reference hole data 493. The reference image data 492 represents a binary reference image generated from design data (CAD data) described later. The reference image represents an area of an ideal wiring pattern to be formed on the printed board 9 (for example, a pattern of a mask used for forming a wiring pattern and hereinafter referred to as a "reference wiring pattern"). The reference hole data 493 represents the coordinates and diameter of the center of each hole portion (ideal hole portion, hereinafter referred to as a "reference hole portion") to be formed on the printed circuit board 9.

4 is a diagram showing a part of a reference image. In Fig. 4, the reference hole portion 73 is superimposed on the reference image and indicated by a two-dot chain line. The reference wiring pattern 70 includes a plurality of lands 71 and a line 72 connected to each land 71. In Fig. 4, only one land 71 and one line 72 are shown. Typically, the land 71 is circular and the line 72 is linear with a constant width. The end of the line 72 connects to the land 71. Further, the reference hole portion 73 is disposed at the center of the land 71. The diameter of the reference hole portion 73 is smaller than the diameter of the land 71. In Fig. 4, the center of the reference hole portion 73 is denoted by the reference mark C1, and the reference hole portion 73 is denoted by the reference mark D1.

In the present embodiment, the reference data 491 is generated from the design data. The design data includes vector data representing an edge of the reference wiring pattern 70 and reference hole data 493 and information for individually specifying the land 71 and the line 72 I never do that. Therefore, the coordinates and the diameter of the center of the land 71 are unknown. On the other hand, as already described, the reference hole portion 73 is disposed at the center of the land 71, and the coordinates of the center C1 of the reference hole portion 73 are already known. Therefore, it can be understood that the coordinates of the center of the land 71 are the same as the coordinates of the center C1 of the reference hole portion 73. [

Here, the kinds of defects caused by the positional deviation of the holes with respect to the respective lands of the printed board 9 will be described. Figs. 5 to 8 are views showing a part of the inspection image acquired by the imaging section 21, and show holes and lands in the printed board 9. Fig. 5 to 8, a part of the edge of the land area 61 representing the circular land and a part of the edge of the line area 62 representing the line are indicated by two-dot chain lines. In the following description, it is assumed that a part of the land area 61 and a part of the line area 62 are overlapped. In the line region 62, the edge of the end overlapping with the land region 61 is straight.

In the example of Fig. 5, the hole area 63 indicating the hole is formed at the center of the land area 61. Fig. That is, positional deviation of the hole portion with respect to the land does not occur, and FIG. 5 shows a steady state. 6 to 8, the hole area 63 is formed at a position shifted from the center of the land area 61. In the example shown in Figs. In detail, the hole area 63 is superimposed on the edge of the land area 61, and Figs. 6 to 8 show so-called land disconnection. 6 to 8 show a state in which a part of the land is removed by the formation of the hole, but in the following description, the land area 61 and the line area 62 are provided with holes (Assumed to be removed) by the formation of the regions.

7 and 8, in the edge of the land area 61, the line area 62 and the overlaid part are nested to form a part or all of the neck and the hole area 63, 7 and Fig. 8 show the state of the neck defect. More specifically, Fig. 8 in which the hole area 63 overlaps with the entirety of the neck shows the actual land on the printed board 9 (the part excluding the hole area 63 in the land area 61) A portion of the region 62 excluding the hole portion region 63) is separated. In the inspection process to be described below, the presence or absence of land breakage, neck breakage, and neck breakage in the land on the printed board 9 is detected.

9A and 9B are diagrams showing the flow of processing in which the pattern inspection apparatus 1 inspects the printed board 9. In the pattern inspection, first, the printed board 9 is put on the stage 22 (see Fig. 1), and the wiring pattern on the printed board 9 is moved by the stage driving unit 23 to the image pickup unit 21 As shown in Fig. Then, the image of the multi-gradation indicating the wiring pattern is obtained as the inspection image by the image pickup unit 21 and outputted to the operation unit 41 (step S11). The inspection image is aligned with the reference image indicated by the reference image data 492 by the calculation unit 41 (step S12). For example, the inspection image and the reference image are aligned by well-known pattern matching.

The hole information acquiring section 411 refers to the reference hole data 493 so that one of the hole portions to be inspected is identified as a spot hole portion and the hole portion data 493 indicated by the reference hole data 493 Based on the coordinates of the center, an area including the target hole portion in the inspection image is specified (step S13). In the following description, a land to be formed with a spot hole portion is referred to as a " remark land ", and a line connected to the noted land is referred to as a " spot line ".

Fig. 10 is a view showing an area including a target hole portion in the inspection image. Fig. The hole information acquiring section 411 acquires the center C1 of the target hole portion indicated by the reference hole portion data 493 (that is, the center of the reference hole portion that is the target hole portion, hereinafter referred to as & ) &Quot;) is taken as the starting point, the filming process for one angular direction is performed. In the film thickness measurement process, the difference between the luminance value of the target pixel and the luminance value of the adjacent pixel adjacent to the target pixel in the above-mentioned angular direction (the absolute value of the difference in the present embodiment, hereinafter referred to as " luminance difference between adjacent pixels " ) Is repeatedly performed while changing the adjacent pixel to the next target pixel. The position at which the difference in luminance between adjacent pixels becomes equal to or greater than the predetermined threshold is the edge point P1 indicating the edge of the hole area 63 (hereinafter referred to as the "target hole area 63") of the target hole, . When the edge point P1 is specified, calculation of the luminance difference with respect to the next target pixel is not performed. Further, the luminance value may be interpolated between adjacent pixels so that the coordinates of the edge point P1 may be obtained in units smaller than the pitch between pixels (the same in other measurement processing).

In the present embodiment, the land area 61 (hereinafter referred to as the "attention land area 61") and the line area 62 (hereinafter referred to as the " The average luminance of the background area that is an area excluding the target land area 61, the target line area 62 and the target hole area 63, and the average luminance of the target hole area 63, Is higher than the average luminance of The difference between the average luminance of the background area and the average luminance of the target hole area 63 is small. Therefore, the edge point P1 is located in the portion of the edge of the target hole area 63 that is included in the wiring pattern area 60 representing the wiring pattern (hereinafter referred to as the "target edge 631") Is specified. The wiring pattern region 60 is a set of the land area 61 of interest and the line of attention 62 area. In Fig. 10, the target edge 631 is indicated by a bold solid line (the same applies to the other drawings referring to the target edge 631). Further, in the wiring pattern forming step (photolithography) on the printed board 9, it is possible to form wiring patterns with high precision with respect to the design data. As described above, the coordinates of the center of the land of interest It can be understood that it is the same as the coordinates of the center C1. Therefore, the reference center C1 can be regarded as the center of the attention land area 61. [

It should be noted that even if the thickness measurement process is performed from the pixel of the reference center C1 to a pixel distant by a distance equivalent to the diameter of the target hole portion indicated by the reference hole portion data 493, , The thickness measurement process in the above-described angular direction is terminated. In this case, the edge point P1 in the angular direction, which is the measurement direction, becomes non-existent. In Fig. 10, the angular direction in which the edge point P1 is not found is indicated by the broken line arrow A1.

When the filming process for one angular direction is completed, the direction rotated about the reference center C1 by the predetermined angle with respect to the angular direction is set as the next angular direction. Then, the film thickness measurement process is performed for the angular direction, and the edge point P1 is searched. In this manner, by setting a plurality of angular directions in all four directions at a predetermined set angular interval with reference to the reference center C1, as shown in Fig. 10, the target edges 631 in one angular direction, A plurality of edge points P1 are obtained (step S14).

10, the pixel of the reference center C1 is included in the target hole area 63. However, when there is a possibility that the pixel of the reference center C1 is not included in the target hole area 63, The edge point P1 may be determined based on a point different from the reference center C1. For example, eight directions set at angular intervals of 45 deg. Are defined with reference to the reference center C1, and a predetermined distance from the reference center C1 in each direction (for example, The luminance value of the pixel which is one-half of the diameter is confirmed. Subsequently, a pixel whose luminance value is relatively low (within a range considered to be the luminance of the attention hole area 63) is specified as a specific pixel, and a representative position (for example, an average position) representing all the specific pixels is obtained . Then, by setting a plurality of angular directions at predetermined constant angular intervals based on the representative position, a plurality of edge points P1, which are points on the target edge 631 in one angular direction, are obtained.

A plurality of edge points P1 indicating the points on the target edge 631 of the target hole area 63 are obtained based on the coordinates of the plurality of edge points P1, The coordinates and the radius of the center of the imaginary circle representing the edge are obtained (step S15). In Fig. 11, the center of the virtual circle is indicated by a point with the code C2, and the radius of the virtual circle is indicated by an arrow with the code R2. In the following description, the center C2 of the virtual circle is treated as the center of the target hole area 63 and is referred to as the center of the target hole part C2. The processing of step S15 is processing for obtaining the coordinates and the radius of the center of the target hole area 63. [

In the hole information acquiring section 411, as in step S14, the filming process for one angular direction is performed with the pixel at the center of the hole of interest B2 as the starting point. 12 and 13, the position at which the luminance difference between adjacent pixels becomes equal to or greater than the predetermined threshold value is specified as the edge point P2 on the target edge 631 of the target hole area 63. [ As will be described later, since the edge point P2 is a candidate of an evaluation point used for discriminating presence / absence of a neck defect, it is hereinafter referred to as a " candidate point P2 ". The coordinates of the candidate point P2 are stored in the arithmetic unit 41. [

Even if a film is processed from the pixel of the center of gravity C2 of the target hole to a pixel distant by a certain distance from the radius R2 of the imaginary circle by a distance (hereinafter referred to as " The pitching process in the angular direction is terminated. In this case, the candidate point P2 in the angular direction is treated as an absent matter, and the angular direction is stored as the non-candidate direction. The no candidate direction is an angle direction in which a candidate point is not obtained by the absence of the target edge 631. [ In Fig. 13, the position of the line-to-line upper limit distance with respect to the center of gravity C2 of the target hole portion is indicated by a broken-line circle denoted by U2. An angular direction in which the candidate point P2 is not found, that is, a non-candidate direction is indicated by an arrow A2 indicated by a broken line.

When the filming process for one angular direction is completed, the direction rotated by a predetermined set angle with respect to the angular direction with respect to the center of gravity C2 of the target hole is set as the next angular direction. Then, the film thickness processing is performed for the angular direction, and the candidate point P2 is searched. In this way, by setting a plurality of angular directions extending in all directions at a predetermined set angular interval with reference to the center of gravity C2 of the target hole, a plurality of candidates, which are points on the target edge 631 in one angular direction, The point P2 is obtained (step S16). For example, on the circumference of the imaginary circle, among the plurality of points located in a plurality of angular directions with respect to the center of gravity C2 of the target hole portion, The distance between two points adjacent to each other in a direction is predetermined to be several pixels.

In step S16, when the distance between the center of attention hole C2 and the candidate point P2 is equal to or less than a distance obtained by subtracting an arbitrary length from the radius R2 of the imaginary circle, It is preferable to prohibit the use thereof in the processing of FIG. In addition, as described above, calculation of the luminance difference between adjacent pixels is not performed with respect to a pixel that is distant from the pixel at the center of the eye of interest B2 at the distance from the pixel at the center. As described above, only the candidate point P2, which is larger than the distance from the center of gravity C2 of the target hole minus an arbitrary length from the radius R2 of the imaginary circle and is equal to or smaller than the line length upper limit, It is possible to ignore the portion of the target edge 631 of the target hole area 63 that becomes a distorted shape.

In the circumferential direction around the center of gravity C2 of the hole of interest, the hole information acquiring section 411 acquires the hole information of the holes A set of non-candidate directions is specified as a non-candidate direction group. In Fig. 13, the set of four non-candidate directions A2 continuing in the circumferential direction becomes the non-candidate direction group A0. In the example of Fig. 13 in which the candidate group A0 exists, it is determined that the target hole area 63 is a land cut-off state overlapping with the edge of the target land area 61, and the land cut- (Step S17). When the land break due to the target hole portion is detected, the process goes to step S18 described later.

In the example of Fig. 12 in which the non-candidate direction group A0 does not exist, it is determined that the land is not in the disconnected state (step S17). If there is a hole to be inspected next in the inspection image (step S24), the process returns to step S13 to specify the next spot hole section. When there is no hole to be inspected next in the inspection image (step S24), the processing in the pattern inspection apparatus 1 is completed.

In the line direction specifying section 412, when the land cut by the target hole is detected, the target line connected to the target land on which the target hole section is formed, based on the reference image, Is specified (step S18). More specifically, in the reference image shown in Fig. 14A, a plurality of angular directions (a plurality of angular directions extending in all directions) as shown in step S16 are set with reference to the reference center C1 of the target hole portion. Then, the luminance values of the pixels arranged in the respective angular directions from the pixels in the reference center C1 are sequentially obtained. As described above, the reference image is a binary image, and the luminance value of the pixel included in the reference wiring pattern 70 (hereinafter referred to as the "pattern luminance value") and the luminance value of the pixel included in the reference wiring pattern 70 The luminance value of the pixel (that is, the luminance value of the background pixel, hereinafter referred to as the "background luminance value") is different. Therefore, when the luminance value of the pixel acquired in the angular direction is the background luminance value, the pixel is specified as an edge point indicating the edge of the reference wiring pattern 70 in the angular direction. The reference wiring pattern 70 in Fig. 14A includes a land of interest 71 and a line of attention 72.

In the preferred processing in the line direction specifying portion 412, the predetermined distance from the reference center C1 (for example, half of the diameter of the reference hole portion 73 which is the target hole portion) in each angle direction Acquisition of the luminance value is started from the pixel. As a result, the processing time until the edge point is specified can be shortened. In a more preferable process, the confirmation process of sequentially checking the brightness values of pixels spaced the same distance from the reference center C1 in the set plurality of (all) angular directions is repeated while the distance is increased by one pixel. At this time, the angle direction in which the edge point is specified is excluded from the next confirmation processing. When the edge point is specified with respect to the angular direction of half or more of the number of angular directions (all angular directions) initially set in the line direction specifying unit 412, the following confirmation processing is performed Lt; / RTI > For example, in the case where the number of times of setting is set to five, from the pixel when the edge point is specified in the angular direction of half or more of the total number of angular directions to the pixel which is separated by five pixels in each of the remaining angular directions A confirmation process is performed. The angular direction in which the edge point is not specified by repeating the set number of times of confirmation processing is determined as the line candidate direction.

In Fig. 14A, the line candidate direction is indicated by a thick solid arrow A3. When the line candidate direction A3 is one, as in the example of Fig. 14A, the line candidate direction A3 is specified as the line direction. 14B, a plurality of consecutive line candidate directions A3 (hereinafter referred to as a group of these line candidate directions A3) in the circumferential direction around the reference center C1 is referred to as &Quot; group ") is obtained, one line candidate direction A3 of the plurality of line candidate directions A3 included in the line candidate direction group is specified as the line direction. When the number of line candidate directions A3 included in the line candidate direction group is an odd number, the center line candidate direction A3 of the line candidate direction A3 is preferably determined as the line direction. When the number of line candidate directions A3 included in the line candidate direction group is an even number, one of the two line candidate directions A3 near the center of the line candidate direction A3 is determined as the line direction .

Further, when a plurality of line candidate directions A3 that are discontinuous in the circumferential direction are acquired as in the example shown in Fig. 14C, each line candidate direction A3 is specified as the line direction. Of course, when there are a plurality of line candidate direction groups discontinuous in the circumferential direction, one line candidate direction A3 included in each line candidate direction group is determined as the line direction.

In the line direction specifying section 412, the distances from the pixels of the reference center C1 to the edge points are stored in each of the plurality of (all) angular directions obtained by the edge points, The median value of the plurality of distances is specified as the radius of the land 71. As described above, since the wiring pattern can be formed precisely with respect to the design data in the wiring pattern forming process (photolithography) in the printed board 9, the land 71, which is obtained in the reference image, The radius of the target land area 61 in the inspection image can be grasped. As described above, in the line direction specifying portion 412, the center C1 of the target hole portion indicated by the reference hole portion data 493 in the reference wiring pattern 70 indicated by the reference image data 492 is set to be By taking the distance from the center of the land of interest to the edge of the reference wiring pattern 70 in each of the plurality of angular directions, the radius of the land of interest area 61 is specified along with the line direction S19).

The line direction and the radius of the landmark area 61 are specified as shown in Fig. 15A, the reference center C1, which is the center of the landmark area 61, An angle? 1 formed by the direction A5 toward the center of gravity C2 of the center of gravity, which is the center, and the line direction A4 is obtained. At this time, the angle? 1 is obtained by setting the clockwise direction from the line direction A4 to the forward direction and the counterclockwise direction to the negative direction from the reference center C1 as a reference. When the magnitude (absolute value) of the angle? 1 is 90 degrees or more, for example, it is judged that there is no possibility of a neck defect due to the attention hole portion (step S20).

In the examples shown in Figs. 15A and 15B, since the magnitude of the angle [theta] 1 is 90 degrees or more, it is determined that the neck deficit does not occur. If there is a hole to be inspected next in the inspection image (step S24), the process returns to step S13 to specify the next spot hole section. When there is no hole to be inspected next in the inspection image (step S24), the processing in the pattern inspection apparatus 1 is completed.

In the examples shown in Figs. 16A to 16D in which the angle? 1 is less than 90 degrees, it is determined that there is a possibility that a neck defect has occurred (step S20), and the process proceeds to step S21 described later. In Fig. 16B, the angle formed by the direction A5 from the reference center C1 to the center of gravity C2 of the target hole portion and the line direction A4 is 0 DEG.

17A, in the inspection image, the candidate point P2a exists in the same angular direction as the line direction A4 on the basis of the center of gravity C2 of the target hole , The candidate point P2a is determined as a judgment point (step S21). The same is true of the examples shown in Figs. 17B and 17C. It can be understood that the decision point P2a is a candidate point located on the side of the target line area 62 on the target edge 631 of the target hole area 63. [ When there are a plurality of line directions A4, a check point P2a is obtained for each line direction A4.

On the other hand, when the candidate point P2 does not exist in the same angular direction as the line direction A4, the existence of the candidate point P2 in the angular direction adjacent to the line direction A4 in the circumferential direction is confirmed do. For example, when the angle? 1 obtained in step S20 is positive, the candidate points in the adjacent angular directions with respect to the line direction A4 in the negative direction (counterclockwise with respect to the reference center C1) (P2) is confirmed. When the candidate point P2 exists in the angular direction, the candidate point P2 is determined as a judgment point. If there is no candidate point P2 in the angular direction, the presence or absence of the candidate point P2 in the angular direction adjoining in the negative direction with respect to the angular direction is confirmed. The above process is repeated until the discrimination point is determined. Thus, in the example shown in Fig. 17D, the candidate point P2a in the angular direction positioned in the negative direction with respect to the line direction A4 is determined as a judgment point. When the angle? 1 obtained in step S20 is negative, the value of the candidate point P2 in the adjacent angular direction in the normal direction (clockwise direction with reference to the reference center C1) with respect to the line direction A4 Is confirmed.

The above-described process in the edition point acquiring section 413 is carried out in such a manner that the line extending in the line direction A4 from the center of gravity C2 of the target hole and the target edge closest to the position where the edge of the target hole area 63 intersects As a judgment point P2a.

18A, the distance D2 between the reference center C1 and the discrimination point P2a is found in the neck defect detection section 414, and the distance D2 is calculated by subtracting the distance D2 between the reference center C1 and the evaluation point P2a, And is compared with the radius R1 of the region 61. [ It is determined that the distance D2 is larger than the radius R1, so that it is determined that the example of Fig. 18A is a neck shortage state (step S22), and the process goes to step S23 described later. The same is true for the examples shown in Figs. 18B and 18C.

On the other hand, as shown in Fig. 19, when the distance D2 is equal to or smaller than the radius R1, it is determined that the neck shortage does not occur (step S22). If there is a hole to be inspected next in the inspection image (step S24), the process returns to step S13 to specify the next spot hole section. When there is no hole to be inspected next in the inspection image (step S24), the processing in the pattern inspection apparatus 1 is completed.

The above processing in the neck defect detecting section 414 is processing for detecting a neck defect due to the target hole section when the discrimination point P2a is located outside the target land area 61. [ 16A), the degree of neck defection becomes larger as the distance D2 is larger and the angle? 1 (see Fig. 16A) already described becomes larger. Therefore, The degree may be classified.

In the neck break detection section 415, the presence or absence of the non-candidate direction group A0 in each of the forward direction and the negative direction is checked with respect to the angular direction of the decision point P2a in the target hole portion where the neck defect is detected do. As shown in Fig. 20, when two unamplified directional groups A0 exist in the normal direction and the negative direction with respect to the angular direction of the decision point P2a based on the center of attention hole portion C2, The representative direction in each of the two non-candidate direction groups A0 is specified. The representative direction in each non-candidate direction group A0 is, for example, an average direction in a plurality of angular directions included in the non-candidate direction group A0, and in FIG. 20, B1 are indicated by arrows.

The angle? 2 formed by the representative direction B1 of the two groups of non-candidate directions A0 (the angle? 2 is an angle range including the angle direction of the judgment point P2a). Is equal to or less than 180 degrees, it is determined that the state shown in Fig. 20 is a neck-disconnected state (step S23). On the other hand, as in the example shown in Figs. 21A and 21B, when there is no candidate direction group A0 in either the forward direction or the negative direction with respect to the angular direction of the decision point P2a, . In addition, even when two unamplified directional groups A0 are present in the normal direction and the negative direction, the angle? 2 formed by the representative direction B1 of the two unamplified directional groups A0 is larger than 180 degrees , It is determined that the neck break state is not satisfied.

As described above, in the neck break detection section 415, the decision point P2a is sandwiched between two non-candidate direction groups A0 that are discontinuous in the circumferential direction, and the two non-candidate direction groups A0, The neck break due to the target hole portion is detected when the angle &thetas; 2 formed by the representative direction B1 of the target portion is equal to or smaller than a predetermined angle. By the determination of the presence or absence of the neck breakage, the inspection of the attention hole portion is completed. If there is a hole to be inspected next in the inspection image (step S24), the process returns to step S13 to specify the next spot hole section. When there is no hole to be inspected next in the inspection image (step S24), the processing in the pattern inspection apparatus 1 is completed.

As described above, in the pattern inspection apparatus 1, the coordinates of the center C2 of the target hole area 63 indicating one target hole portion are acquired in the inspection image, and the target line is set as the target land The line direction A4, which is the direction of stretching as a viewpoint, is specified. Subsequently, in the inspection image, the object edge (the edge closest to the position where the line extending in the line direction A4 from the center C2 of the target hole area 63 intersects with the edge of the target hole area 63) 631 are obtained as the marked points P2a. Then, when the judgment point P2a is located outside the noted land area 61, a neck defect due to the above-mentioned spot hole portion is detected. As a result, the neck defect can be detected easily. Further, compared with the pattern inspection of the comparative example in which the processing based on the luminance value is performed for all the pixels in the vicinity of the land, the amount of calculation can be reduced in the pattern inspection processing. As a result, it is possible to detect a neck defect without using an expensive circuit, and it is possible to reduce the cost related to inspection of the printed circuit board 9. [

In the inspection image, a plurality of angular directions are set at a constant angular interval with reference to the center C2 of the target hole area 63, so that each of the angular directions on the target edge 631 in one angular direction A plurality of candidate points P2 are obtained, and one candidate point among the plurality of candidate points P2 is obtained as the judgment point P2a. This makes it easy to acquire the evaluation point P2a.

The center of the attention hole area indicated by the reference hole data 493 is the center C1 of the landmark area 61 and the distance between the center C1 of the landmark area 61 and the decision point P2a (D2) and the radius R1 of the noted land area 61 are compared. As a result, the neck defect can be more easily detected.

The line direction specifying section 412 specifies the center C1 of the target hole portion indicated by the reference hole portion data 493 in the reference wiring pattern 70 indicated by the reference image data 492 to the center of the target land 71 The distance from the center C1 of the land of interest 71 to the edge of the reference wiring pattern 70 in each of the plurality of angular directions is obtained as the distance C1. Thus, it is possible to easily specify the radii of the line direction A4 and the remark land 71 (the attention land area 61).

The hole information acquiring unit 411 confirms the presence of the non-candidate direction group A0 which is a set of a predetermined number or more of the non-candidate directions A2 that are continuous in the circumferential direction. As a result, it is possible to easily detect land disconnection due to the attention hole portion.

In the neck break detection section 415, the decision point P2a in the target hole portion where the neck defect is detected is sandwiched between two non-candidate direction groups A0 that are discontinuous in the circumferential direction, It is confirmed whether the angle formed by the representative direction B1 of the non-candidate direction group A0 is equal to or less than a predetermined angle. This makes it possible to easily detect the neck break due to the attention hole portion.

The pattern inspecting apparatus 1 determines whether or not the direction from the center C1 of the target land area 61 to the center C2 of the target hole area 63 and the angle formed by the line direction A4 when the angle? 1 is equal to or larger than a predetermined angle, acquisition of the discrimination point P2a with respect to the target hole portion is not performed. As a result, it is possible to omit the processing related to the acquisition of the discrimination point P2a with respect to the target hole portion, which is not the neck defect, and the pattern inspection in the pattern inspection apparatus 1 can be completed in a short time.

In the pattern inspection apparatus 1, various modifications are possible.

In the above embodiment, the reference image data 492 is prepared as the reference pattern data representing the reference wiring pattern, but the vector data representing the reference wiring pattern may be used as the reference pattern data.

In the above-described embodiment, the line direction can be easily specified by using the reference pattern data indicating the reference wiring pattern and not showing the hole portion. However, depending on the accuracy of the wiring pattern formed on the printed circuit board 9 or the like , The line direction may be specified based on the inspection image.

In the neck defect detecting section 414, when the discrimination point P2a is located in the target line area 62 indicating the target line, the neck defect due to the target hole portion may be detected. In this case, a straight line edge (see Figs. 6 to 8) of the end portion overlapping with the landmark area 61 in the target line area 62 is recognized as a neck. For example, when the reference image data includes data indicating the land and the line separately as reference pattern data, including the image data representing the land and the image data representing the line, ) Is located outside the noted land area 61, or whether it is located in the target line area 62. [0060]

Depending on the design of the pattern inspection apparatus 1, without setting a plurality of angular directions based on the center C2 of the target hole area 63 (without obtaining a plurality of candidate points) .

The configurations of the embodiment and the modified examples may be appropriately combined as long as they do not contradict each other.

While the invention has been described and illustrated in detail, the foregoing description is illustrative and not restrictive. Therefore, many modifications and variations are possible without departing from the scope of the present invention.

1: Pattern inspection device 9: Printed substrate
49: storage unit 60: wiring pattern area
61: attention land area 62: attention line area
63: attention hole area 70: reference wiring pattern
71: Land of attention 72: line of attention
73: reference hole section 411: hole section information acquisition section
412: line direction specifying section 413:
414: Neck defect detecting section 415: Neck defect detecting section
491: Reference data 492: Reference image data
493: reference hole data 631: target edge
A0: No candidate direction group A2: No candidate direction
A4: Line direction B1: (Direction of non-candidate direction) Representative direction
C1: Reference center C2: Center of the attention hole
P2: Candidate point P2a:
S11 to S24:

Claims (14)

A pattern inspection apparatus for a printed circuit board,
A hole pattern information obtaining section for obtaining coordinates of a center of a target hole area indicating one target hole section in a wiring pattern including lands and lines and a test image obtained by photographing a printed board on which a hole is formed,
The reference pattern data indicating the wiring pattern or the reference line connected to the landmark on which the landmark hole is formed based on the inspection image is a line specifying a line direction which is a direction in which the landmark is extended A direction specifying portion,
A line extending from the center of the target hole area to the line direction and having a portion included in a wiring pattern area representing the wiring pattern as an edge of the target hole area, As an evaluation point, a point on the target edge closest to a position where the edge of the target hole area crosses;
And a neck defect detecting section for detecting a neck defect due to the target hole section when the discrimination point is located outside the target land area indicating the target land or in the target line area indicating the target line , Pattern inspection device. The method according to claim 1,
Wherein the hole information acquiring section sets a plurality of angular directions at a predetermined angular interval with reference to the center of the target hole area in the inspected image so that each of the plurality of angular directions on the target edge in one angular direction A plurality of candidate points are obtained,
And the evaluation point acquiring unit acquires one of the plurality of candidate points as the evaluation point. The method of claim 2,
Further comprising a storage unit for storing the reference pattern data and reference data including reference hole data indicating coordinates of a center of the hole,
Wherein the line direction specifying section specifies the center of the target hole portion indicated by the reference hole portion data in the wiring pattern represented by the reference pattern data from the center of the target land to the plurality of angles Direction to the edge of the wiring pattern in each of the plurality of directions, and specifies the radius of the line direction and the landmark area. The method of claim 3,
Wherein the neck defect detection unit detects the distance between the center of the noted land area and the plate star point and the distance between the center of the noted land area and the center of the noted land area, And detects the neck deficiency by comparing the radii. The method according to any one of claims 2 to 4,
The hole information acquiring section may be arranged such that an angular direction in which candidate points are not obtained by the absence of the target edge is a non-candidate direction, and a non-candidate direction group which is a set of a predetermined number or more of non-candidate directions continuous in the circumferential direction exists , And detects a land break due to the target hole portion. The method of claim 5,
Wherein the discrimination point in the target hole portion in which the neck defect is detected is sandwiched between two groups of non-candidate direction groups discontinuous in the circumferential direction, and an angle formed by the representative directions of the two non- And a neck break detecting portion for detecting a break of the neck caused by the target hole portion when the angle is less than or equal to an angle of the neck. The method according to any one of claims 1 to 4,
In the inspection image, when the angle between the direction from the center of the target land area to the center of the target hole area and the line direction is equal to or larger than a predetermined angle, And does not acquire the above-mentioned evaluation point for the pattern inspection apparatus. 1. A pattern inspection method for a printed circuit board,
a) obtaining a coordinate of a center of a target hole area indicating one target hole portion in a wiring pattern including lands and lines and a test image obtained by photographing a printed board on which a hole is formed;
b) a reference pattern data indicating the wiring pattern or a reference line connected to a landmark in which the landmark hole is formed, based on the inspection image, is specified as a line direction that is a direction of extending the landmark land as a starting point ;
c) In the inspection image, a portion included in a wiring pattern region which is the edge of the target hole region and which is included in the wiring pattern region is set as a target edge, and a portion extending from the center of the target hole portion region in the line direction And a point on the target edge closest to a position where the line intersects the edge of the target hole area as a judgment point;
d) a step of detecting a neck defect due to the target hole when the discrimination point is located outside the target land area indicating the target land or in the target line area indicating the target line , Pattern inspection method. The method of claim 8,
e) After the step a), in the inspection image, by setting a plurality of angular directions at a constant angular interval with reference to the center of the target hole area, And a step of finding a plurality of candidate points,
And in the step c), one candidate point among the plurality of candidate points is obtained as the discriminant point. The method of claim 9,
Reference data including reference pattern data and reference hole data indicating coordinates of a center of the hole portion are prepared in advance,
Wherein in the step b), in the wiring pattern indicated by the reference pattern data, the center of the target hole portion indicated by the reference hole portion data is set as the center of the target land, The line direction and the radius of the land area are determined by acquiring the distance to the edge of the wiring pattern in each of the angular directions. The method of claim 10,
Wherein in the step d), the center of the target hole area indicated by the reference hole data is the center of the target land area, and the distance between the center of the target land area and the plate star point, The neck defect is detected by comparing the radius of the neck defect. The method according to any one of claims 9 to 11,
In the step (e), there is a candidate direction group which is a set of a predetermined number or more of non-candidate directions continuous in the circumferential direction, with the angular direction in which candidate points are not obtained by the absence of the target edge, A land break due to the target hole portion is detected. The method of claim 12,
Wherein the discrimination point in the target hole portion in which the neck defect is detected is sandwiched between two groups of non-candidate direction groups discontinuous in the circumferential direction, and an angle formed by the representative directions of the two non- Detecting a neck break due to the target hole portion when the angle is less than or equal to a predetermined angle. The method according to any one of claims 8 to 11,
In the inspection image, in the case where the angle formed by the direction from the center of the noted land area to the center of the target hole area and the line direction is a predetermined angle or more, in the step c) Wherein the step of acquiring the discrimination point for the part is not performed.

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