KR100975832B1 - Denting inspecting apparatus and method thereof - Google Patents

Abstract

The present invention relates to an indentation inspection apparatus and method for inspecting the indentation generated on the substrate, and more particularly, the setting of the inspection area requiring the indentation inspection can be quickly and accurately, as well as can quickly and accurately inspect the presence of indentation Indentation inspection apparatus and method.

To this end, the indentation inspection apparatus according to the present invention is a work stage for fixing the substrate on which the indentation is generated, located on the upper side of the work stage, a microscope for observing the rear surface of the substrate, the substrate observed through the microscope An inspection area selecting unit and an inspection area for setting an inspection area requiring an indentation test of the image data, the camera being connected to the microscope, the camera mounted to the microscope, and receiving the image data from the camera so as to photograph the rear surface of the lens; And a indentation detector for detecting luminance distribution information for each detection region having a predetermined shape and detecting an indentation index according to the detected luminance distribution information.

Semiconductor chip, substrate, indentation, microscope, camera, luminance distribution

Description

Indentation apparatus and method

The present invention relates to an indentation inspection apparatus and method for inspecting the indentation generated on the substrate, in particular, the indentation inspection apparatus that can quickly and accurately inspect the presence or absence of the indentation, as well as the setting of the inspection area requiring the indentation inspection And to a method.

Recently, a flat panel display panel (M) used in various electronic devices including mobile phones, PDAs, and display devices has been manufactured using a wireless bonding technique, COG (Chip On Glass) and COF (Chip On Film). , Flexible Printed Circuit (FPC) and Tape Carrier Package (TCP) are adopted.

For example, the flat panel display panel M is a glass substrate 1 on which a panel electrode 4 made of a plurality of ITO or the like is formed, as shown in FIG. 1 showing a COG method, and on the glass substrate 1 for driving thereof. A semiconductor chip 2 (or a driving chip) or the like mounted on the substrate, and is pressed between the glass substrate 1 and the semiconductor chip 2 with an anisotropic conductive material 3 such as an anisotropic conductive film (ACF) interposed therebetween. Produced by

In addition, a chip electrode 5 is formed on one surface of the semiconductor chip 2 corresponding to the panel electrode 4 as shown in FIG. 2, and bumps 7 are formed on the chip electrode 5, thereby providing a semiconductor. When the chip 2 is pressed, the lower surface 7a of the bump 7 is cured while compressing the conductive particles 6 included in the conductive material 3, whereby the panel electrode 4 and the chip electrode 5 mutually harden. Electrically connected.

In this case, the electrical conductivity between the glass substrate 1 and the semiconductor chip 2 is ensured by sufficiently compressing a sufficient number of conductive particles 6 by the bumps 7, and thus the flat panel display panel M having the above structure In manufacturing the material, a process of checking whether the conductive particles 6 are sufficiently compressed by the bumps 7 is essential.

To this end, a non-differential microscope (not shown) is adopted so that fine indentations 8 formed in the panel electrode 4 can be seen through the glass substrate 1 above the glass substrate 1, as shown in FIG. By inspecting the image of the indentation 8 observed through the undifferentiated microscope through a camera (not shown) to obtain image data, the indentation 8 in which the panel electrode 4 is pressed by the conductive particles 6 is inspected. The way to do it is used.

However, in inspecting the indentation 8 in this manner, the inspection area requiring the indentation 8 inspection, such as the bump 7 mounting area, is very small in units of several micrometers (um), so that the inspection area can be quickly selected. Of course, there was a problem that it is difficult to select correctly.

In addition, when inspecting the abnormality of each indentation 8 in the inspection area, it is necessary to confirm that the indentation 8 is formed at a sufficient depth and at a proper location with an appropriate distribution. There was also a problem that it is difficult to inspect each indentation 8 produced by a) quickly and accurately.

The present invention has been proposed to solve the above-described problems, and in inspecting the indentation generated on the substrate, the inspection area requiring the indentation inspection is not only quick and accurate, but also the presence of the indentation can be quickly and accurately inspected. To provide an indentation inspection apparatus and method that can be.

To this end, the indentation inspection apparatus according to the present invention includes a work stage for fixing the substrate on which the indentation occurred; A microscope positioned above the work stage and configured to observe a rear surface of the substrate; A camera connected to the microscope so as to capture a rear surface of the substrate observed through the microscope; An inspection region selection unit which receives the captured image data from the camera and sets an inspection region in which an indentation inspection is required among the image data; And an indentation detector for detecting luminance distribution information for each detection region having an edge of a predetermined shape in the inspection region and detecting an indentation index according to the detected luminance distribution information.

At this time, the indentation detection unit is to determine the normal indentation according to the indentation index, it is preferable to test the electrical conduction state in the inspection area in accordance with the number of normal indentations present in the inspection area.

In addition, the inspection area selection unit, the master data storage unit for receiving and storing the same master data as the substrate pattern of the design drawing; A mark data storage section for selecting a portion of the image data and storing an image of the selected portion as a mark; An offset value storage unit for storing an offset value between the mark of the image data and the inspection area of the image data using the master data including the mark and pattern information corresponding to the inspection area; And a matching unit for matching the inspection area to a position corrected by the offset value based on the mark of the image data.

The indentation detector may further include an image data analyzer configured to analyze a luminance distribution of the inspection area among the image data; A center point detector for detecting center points of the detection area from the analyzed image data; An area storage unit for storing the edge and area information having a predetermined shape around the center point; A height detecting unit detecting a height of an indentation in the edge having the area by using the analyzed luminance; And an indentation index calculator for detecting the indentation index using the area and the height.

In addition, the indentation index is preferably detected by applying a formula of (0.7 * height) + (0.3 * area).

In addition, the area is preferably set to a different value according to the material of the adhesive material inserted between the semiconductor chip and the substrate.

In addition, it is preferable to further include an indentation index reference value storage unit for storing the indentation index reference value to be able to detect the presence or absence of the indentation by comparison with the detected indentation index.

In addition, the indentation reference value is preferably set to different values depending on the material of the adhesive material inserted between the semiconductor chip and the substrate.

In addition, it is preferable that an illumination device for irradiating light perpendicular to the substrate through the microscope is provided.

On the other hand, the indentation inspection method according to the present invention comprises a substrate fixing step of fixing the indentation generated substrate to the work stage to be exposed toward the microscope; A substrate observation step of observing the substrate using a microscope; A substrate imaging step of photographing the back side of the observed substrate using a camera; An inspection region setting step of receiving the photographed image data and setting an inspection region requiring an indentation inspection among the image data; A luminance distribution detecting step of detecting luminance distribution information for each detection region having a predetermined shape border within the inspection region; And an indentation index detecting step of detecting an indentation index according to the detected luminance distribution information.

At this time, the inspection region setting step, the master pattern storage step of receiving and storing the same master data as the substrate pattern of the design drawing; A mark storing step of selecting a portion of the image data and storing an image of the selected portion as a mark; An offset value detecting step of detecting an offset value between a mark of the image data and an inspection region of the image data by using the master data including the mark and pattern information corresponding to the inspection region; And a matching step of matching the inspection area to a position corrected by the offset value based on the mark of the image data.

The brightness distribution detecting step may further include: a detection area data storing step of receiving and storing information on an edge and an area having a predetermined shape representing each detection area subdividing the inspection area; An image data analysis step of analyzing the luminance of the inspection area among the image data; A center point detection step of detecting center points of the detection area using the analyzed luminances; And a height detection step of detecting a height of an indentation in the edge having the area by using the analyzed luminance.

The indentation inspection apparatus and method according to the present invention as described above, in determining whether the semiconductor chip is normally mounted on the substrate, it is possible to improve the speed and accuracy of setting the inspection area requiring the indentation inspection. In addition, it is also possible to improve the speed and accuracy of the inspection of the abnormality of the indentation.

Hereinafter, an indentation inspection apparatus and method according to a preferred embodiment of the present invention with reference to the accompanying drawings to be described in detail.

However, hereinafter, a flat display panel using a COG method among chip on glass (COG), chip on film (COF), flexible printed circuit (FPC), tape carrier package (TCP), and various other wireless bonding techniques will be taken as an example. Explain.

Therefore, the substrate to be examined in the following will be a glass substrate.

Figure 4 is a schematic diagram showing the indentation inspection apparatus according to the present invention, Figure 5 is a block diagram showing the inspection portion of the indentation inspection apparatus according to the present invention, Figure 6 is the inspection area setting of the indentation inspection apparatus according to the present invention 7 is a flowchart schematically showing the method, and FIG. 7 is a flowchart schematically showing the indentation inspection method of the indentation inspection apparatus according to the present invention.

Referring to FIG. 4 with reference to FIGS. 1 to 3, the indentation inspection apparatus 100 according to the present invention is for fixing the flat panel display panel M (hereinafter, referred to as a 'panel') in which the indentation 8 is generated. A microscope 120 for finely observing the rear surface of the panel M including the work stage 110 and the glass substrate (see 1 in FIG. 1) on which the semiconductor chip (see 2 in FIG. 1) is mounted, and the panel M The camera 130 is connected to the microscope 120 to capture the back of the camera, the auxiliary camera 130a for adjusting the focus of the microscope 120, and the driving of the microscope 120 and the lighting device 160. In addition to the control, the inspection server 140 for setting the inspection area requiring the indentation inspection of the image data captured by the camera 130, and inspects the indentation (8) using the luminance distribution information of each indentation (8), It includes a drive server 150 for controlling the drive of the work stage 110 and the lighting device 160 for irradiating light perpendicular to the substrate do.

The panel M has a rear surface of the panel M such that the rear surface of the glass substrate 1 on which the semiconductor chip 2 is mounted is exposed toward the microscope 120 installed on the upper side of the work stage 110. The upper surface of the glass substrate 1 is fixed to the work stage 110 and the microscope 120 irradiates light perpendicularly to the glass substrate 1 using the lighting device 160. The microscopic observation of the indentation 8 generated through the front panel electrode 4 (or also referred to as the “ITO electrode”) is carried out. The camera 130 captures the indentation 8 observed in this way to capture image data. Enables transmission to inspection server 140.

Accordingly, the inspection server 140 selects an inspection region from the input image data and inspects each indentation 8 of the selected inspection region, thereby inspecting the panel electrode 4 and the panel M of the glass substrate 1. It is possible to check the electrical conduction state of the semiconductor chip 2 (or also referred to as a 'drive IC') for driving and controlling.

More specifically, the work stage 110 to fix and move the inspection target panel (M), the X-axis and Y-axis on the horizontal plane by a drive motor (not shown) controlled by the drive server 150 Of course, it is possible to move to, if necessary, is also configured to be rotated, it is possible to make the primary adjustment to position the inspection area of the glass substrate 1 directly under the microscope (120).

The panel M can be fixed by a jig (not shown) mounted on the upper surface of the work stage 110. However, in recent years, a vacuum adsorption method is widely used to protect the glass substrate 1, which is becoming thinner.

The microscope 120 is installed on the upper side of the work stage 110 to which the panel M is fixed, and penetrates the rear surface of the glass substrate 1 to form an indentation generated in the panel electrode 4 on the front surface of the glass substrate 1 ( 8), the microscope 120 is preferably an undifferentiated microscope 120 to more accurately observe the luminance distribution required for the indentation test, as described below.

In addition, the microscope 120 receives an image captured by the auxiliary camera 130a connected to the microscope 120 from the monitoring server 140, and determines a current focus state according to the received image. It is configured to be movable up and down by the control of 140.

The camera 130 is for capturing the rear surface of the glass substrate 1 observed by the microscope 120. The camera 130 is connected to the microscope 120 and simultaneously photographed image data to the inspection server 140. It is connected to the inspection server 140 to be transmitted.

The illumination device 160 is perpendicular to the glass substrate 1 of the panel M so that the indentation 8 generated in the panel electrode 4 of the glass substrate 1 can be clearly observed through the microscope 120. In order to irradiate light, the light supplied from the illumination device 160 is supplied to the inside of the microscope 120 and passes through a polarizing filter (not shown) and a prism (not shown) therein and then the work stage 110. In the upper portion of the glass substrate (1) to be able to irradiate light.

The inspection server 140 sets the inspection area requiring the indentation inspection and inspects the indentation 8 using the luminance distribution information of each indentation 8, as can be seen from FIG. An image data storage unit 144 for receiving and storing image data captured from the image 130, an inspection region selecting unit 141 for setting an inspection region requiring indentation inspection of the image data, and each indentation in the inspection region ( 8, the indentation detection unit 142 for detecting the luminance distribution information for each detection region and detecting the indentation index according to the detected luminance distribution information, and allowing a user such as an inspector to input various kinds of information necessary for the inspection. The input unit 143 and a control unit 145 for controlling them overall.

Here, the inspection area selecting unit 141 selects a part of the image data and a master data storage unit 141a which receives and stores the same master data as the substrate pattern on the design drawing, and marks an image of the selected part. To store the offset value between the mark of the image data and the inspection area of the image data by using the mark data storage unit 141b to be stored as) and master data including pattern information corresponding to the mark and the inspection area. The offset value storage unit 141c and a matching unit 141d for matching the inspection area to a position corrected by the offset value based on the mark of the image data.

Therefore, as shown in Fig. 6A, a part of the image data in which the panel electrode 4 and the indentation 8 are imaged is set as a mark, and then stored in the mark data storage unit 141b, and Fig. 6B By using the corresponding master data stored in the master data storage unit 141a, the offset value between the mark area corresponding to the mark and the inspection area is obtained, and stored in the offset value storage unit 141c. As described above, the matching unit 141d applies an offset value from the mark of the image data so that the corrected position can be selected as the inspection region in the image data that requires the actual inspection.

Here, although the position where the bump 7 is mounted is described as an example of the inspection area, the present invention is not limited thereto, and it is obvious that other parts can be set as the inspection area by the above method.

The indentation detector 142 includes an image data analyzer 142a for analyzing the luminance distribution of the inspection area, a center point detector 142b for detecting the center point of each detection area in the inspection area from the analyzed image data, and the center point. An area storage unit 142c for storing predetermined edge shape and area information as a center, and a height detection unit 142d for detecting the height H of the indentation 8 using the analyzed luminance. And an indentation index calculator 142e for detecting an indentation index using the area and the height H.

Here, the image data analysis unit 142a enables the image data corresponding to the inspection area to be analyzed by the luminance detection method. That is, as shown in (a) of FIG. 7, the larger or higher the indentation part 8 appears brighter, the darker the indentation part 8 is smaller or lower part appearing darker. In the bright part, the conductive particles are sufficiently compressed by the bumps 7. As such, it can be used as a basis that can be recognized as electrically appropriately connected with the panel electrode 4 of the glass substrate 1.

The center point detector 142b may select a center point of the detection area in the inspection area, which will be described later, on the basis of the data analyzed by the image data analyzer 142a. 8) It can be selected based on the generation unit.

That is, the center point is selected between indentations 8 adjacent to each other, as shown in FIG. The center of the corresponding indentation 8, which is the brightest, is selected as the center point so that it can be used as the center point of the detection area.

The area storage unit 142c stores the detection area data preset by the inspector, and the detection area data includes the edge shape, the radius length, and the area information of the detection area. That is, if the edge of the detection area is stored in the area storage unit 142c having a circular shape and a radius of a predetermined length is stored at the same time, the radius is centered on the center point as shown in FIG. A circle having an angle is set as a detection area, and the area of the detection area is stored.

However, the detection area may be stored in a rectangular or hexagonal shape in addition to a circular shape. When the detection area is a square or hexagonal shape, the detection area may be more closely inspected.

In addition, the radial length may vary depending on the type of conductive material (see 3 in FIG. 1), such as ACF, which may vary in size depending on the conductive material 3, and thus, an appropriate detection area. Because you need to choose.

The height detector 142d detects the height H of the indentation 8 by using the luminance analyzed by the image data analyzer 142a. The height detector 142d has a deep indentation 8. The height H of the indentation 8 is detected by applying the principle that the higher the height H of the indentation 8 is generated, the brighter the brightness is.

The indentation index calculation unit 142e calculates the indentation index using the area and the height H as variables, and the distribution degree of the indentation 8 existing per predetermined area, that is, the indentation 8 It is checked whether the indentation 8 is normally generated by using the distribution information of the luminance changed by.

To this end, the indentation index calculation unit 142e is applied to the indentation index (F) calculation formula as follows.

Formula: Indentation Index (F) = (0.7 * Height) + (0.3 * Area)

However, in order to calculate the indentation index F, the constants multiplied by the height H and the area, respectively, may vary depending on the kind of the conductive material 3 for the reasons described above.

Therefore, as shown in FIG. 7C, the indentation index F in each detection region where the indentation 8 is located is obtained, and the indentation index F of the detected specific detection region satisfies the indentation index reference value. Only if it is determined that the normal indentation, and further by checking the number of such normal indentation (8) in the entire inspection area it is possible to confirm the electrical conduction state.

On the other hand, if the indentation index F of the detected specific detection area is smaller than the indentation index reference value, it is judged that there is not sufficient compression or other noise. On the contrary, the indentation index F is larger than the indentation index reference value. In this case, it is judged that excessive compression or other noise is caused.

Hereinafter, the indentation inspection method using the indentation inspection apparatus of the present invention as described above will be described in detail.

First, when the inspection is started, the glass substrate 1 having the semiconductor chip 2 mounted on the front surface by crimping is fixed on the work stage 110 so that the rear surface thereof is exposed toward the microscope 120.

When the glass substrate 1 is fixed, the drive server 150 controls the driving motor (not shown) to move the work stage 110 so that the glass substrate 1 is located directly under the microscope 120, The inspection server 140 moves the microscope 120 upward or downward based on the image input through the auxiliary camera 130a to adjust the focus.

In addition, the inspection server 140 operates the illumination device 160 so that light is irradiated perpendicularly to the glass substrate 1 through the inside of the microscope 120, and when the light is irradiated to the glass substrate 1, the microscope The rear surface of the glass substrate 1 on which the semiconductor chip 2 is mounted is observed using the 120.

When the rear surface of the glass substrate 1 is observed through the microscope 120, the observed image data is captured by the camera 130 and then transmitted to the image data storage unit 144 of the inspection server 140.

Then, the picked-up image data is input to set an inspection area for indentation inspection of all the image data.

That is, a part of the image data is selected, and the image of the selected portion is stored as a mark in the mark data storage unit 141b, and stored in the master data storage unit 141a, and corresponding to the mark and inspection area. The offset value between the mark and the inspection area is detected using the master data including the substrate pattern information in the figure.

The inspection area is set by storing the detected offset box in the offset box storage unit 141c and matching the inspection area to a position corrected by the offset value based on the mark of the image data using the matching unit 141d.

When an inspection area of the image data is set, luminance distribution information is detected for each detection area in the inspection area. The luminance distribution is stored by the inspector in the area storage unit 142c through the input unit 143, and the inspection area is subdivided. Information about an edge and an area of a predetermined shape representing each detection area is used.

That is, the image data analysis unit 142a analyzes the luminance of the portion corresponding to the inspection area, and the center point detection unit 142b detects the center points of the detection area as described above using the analyzed luminance, respectively. The indentation height H in the edge having the area is detected by using the luminance analyzed by the height detection unit 142d, so as to be used for detection of the indentation index as described later.

Therefore, when the indentation index is calculated using the area and the height H as variables in the indentation index calculation unit 142e, the distribution degree of the indentation 8 existing per predetermined area, that is, the indentation 8 It is possible to confirm whether the indentation 8 has been normally generated by using the distribution information of the luminance changed by.

That is, if the detected indentation index (F) is smaller than the indentation index reference value, it is judged that there is not enough compression or other noise. On the contrary, if the indentation index (F) is larger than the indentation index reference value, excessive crimping is performed. This is determined by the noise or other noise, and it is judged as a normal indentation only when the indentation index F satisfies the indentation index reference value.

Subsequently, the above indentation index detection is repeatedly performed for each detection area in the inspection area, and when the indentation index detection for all detection areas is completed, the normal indentation number existing in the entire inspection area is checked to confirm the electrical conduction state. do.

On the other hand, when the indentation test is completed in the above manner, the test is terminated and the result is stored.

In the above, the specific Example of this invention was described above. However, the spirit and scope of the present invention is not limited to these specific embodiments, and various modifications and variations can be made without departing from the spirit of the present invention. Those who have it will understand.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The indentation inspection apparatus and method according to the present invention, when inspecting the indentation generated on the substrate, it is possible to improve the speed and accuracy of the setting of the inspection area requiring the indentation inspection. In addition, it is also possible to improve the speed and accuracy of the inspection of the abnormality of the indentation.

1 is a perspective view illustrating a general flat panel display panel.

2 is a partially enlarged view illustrating an indentation part of a general flat display panel.

3 is an installation state diagram for inspecting a general flat panel display panel.

Figure 4 is a schematic view showing an indentation inspection apparatus according to the present invention.

5 is a block diagram showing an inspection unit of the indentation inspection apparatus according to the present invention.

6 is a flowchart schematically illustrating a method for setting an inspection area of an indentation inspection apparatus according to the present invention.

7 is a flow chart schematically showing the indentation inspection method of the indentation inspection apparatus according to the present invention.

<Explanation of symbols for the main parts of the drawings>

M: flat panel display panel

110: work stage

120: microscope

130: camera

140: inspection server

150: drive server

F: Indentation Index

Claims (12)

A work stage for fixing the substrate on which the indentation is generated in the process of pressing and mounting the semiconductor chip; A microscope positioned above the work stage and configured to observe a rear surface of the substrate; A camera connected to the microscope so as to capture a rear surface of the substrate observed through the microscope; An inspection region selection unit which receives the captured image data from the camera and sets an inspection region in which an indentation inspection is required among the image data; And An indentation detector for detecting luminance distribution information for each detection region having an edge of a predetermined shape within the inspection region, and detecting an indentation index according to the detected luminance distribution information ; Including but not limited to: The inspection area selection unit, A master data storage unit for receiving and storing master data identical to the substrate pattern of the design drawing; A mark data storage section for selecting a portion of the image data and storing an image of the selected portion as a mark; An offset value storage unit for storing an offset value between the mark of the image data and the inspection area of the image data using the master data including the mark and pattern information corresponding to the inspection area; And And a matching unit matching the inspection area to a position corrected by the offset value based on the mark of the image data. The indentation detector, An image data analyzer which analyzes the luminance distribution of the inspection area among the image data; A center point detector for detecting center points of the detection area from the analyzed image data; An area storage unit for storing the edge and area information having a predetermined shape around the center point; A height detecting unit detecting a height of an indentation in the edge having the area by using the analyzed luminance; And Includes; indentation index calculation unit for detecting the indentation index using the area and height; The indentation index calculation unit is indentation inspection device, characterized in that for detecting the indentation index by applying the formula of (height constant × height) + (area constant × area). The method of claim 1, The indentation detection unit, the indentation inspection apparatus characterized in that it determines a normal indentation according to the indentation index, and examines the electrical conduction state in the inspection region in accordance with the number of normal indentations present in the inspection region. delete delete delete The method of claim 1, And the area is set to a different value according to a material of an adhesive material inserted between the semiconductor chip and the substrate. The method according to any one of claims 1, 2 or 6, Indentation inspection apparatus further comprises an indentation index reference value storage unit for storing the indentation index reference value to detect whether there is an abnormality of the indentation through comparison with the detected indentation index. The method of claim 7, wherein The indentation index reference value is set to a different value according to the material of the adhesive material inserted between the semiconductor chip and the substrate. The method according to any one of claims 1, 2 or 6, Indentation inspection device, characterized in that the illumination device for irradiating light perpendicular to the substrate through the microscope is installed. A substrate fixing step of fixing the substrate having the indentation in the process of pressing and mounting the semiconductor chip to the work stage to expose the substrate toward the microscope; A substrate observation step of observing a rear surface of the substrate using the microscope; A substrate imaging step of photographing the back side of the observed substrate using a camera; An inspection region setting step of receiving the photographed image data and setting an inspection region requiring an indentation inspection among the image data; A luminance distribution detecting step of detecting luminance distribution information for each detection region having a predetermined shape border within the inspection region; And Indentation index detection step of detecting the indentation index in accordance with the detected luminance distribution information; including, The inspection area setting step, A master pattern storage step of receiving and storing master data identical to the substrate pattern of the design drawing; A mark storing step of selecting a portion of the image data and storing an image of the selected portion as a mark; An offset value detecting step of detecting an offset value between a mark of the image data and an inspection region of the image data by using the master data including the mark and pattern information corresponding to the inspection region; And And a matching step of matching an inspection area to a position corrected by the offset value based on the mark of the image data. The luminance distribution detection step, A detection area data storage step of receiving and storing information on an edge and an area having a predetermined shape representing each detection area subdivided into the inspection area; An image data analysis step of analyzing the luminance of the inspection area among the image data; A center point detection step of detecting center points of the detection area using the analyzed luminances; And And a height detection step of detecting the indentation height in the edge having the area by using the analyzed luminance. The indentation index detection step is to detect the indentation index by applying a formula of (height constant × height) + (area constant × area). delete delete

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