KR101367193B1 - Inspection method for horizontality and pressure of collet - Google Patents

Abstract

The present invention relates to a method for inspecting horizontality and pressure of a collet, capable of automatically inspecting a failure in a horizontality or abrasion state and a pressure state of the collet by using color information of a stamp image carved in a piece of pressure sensitive paper. The method for inspecting horizontality and pressure of a collet in the present invention includes a first step of obtaining image information of the pressure sensitive paper including a plurality of the stamp images corresponding to the shape of the collet; a second step of setting a plurality of unit inspection areas in order to individually include one stamp within an image of the pressure sensitive paper; a forth step of dividing each unit inspection area into block units and calculating a color average value by each block or the unit inspection area; and a fifth step of determining whether the horizontality and the pressure are normal by comparing the color average value by each block and the color average value on each unit inspection area. [Reference numerals] (S10) Obtaining image information of a pressure sensitive paper; (S11) Setting a plurality of unit inspection areas; (S12) Dividing an unit inspection area into blocks; (S13) Calculating a color average value by each block or the unit inspection area; (S14) Determining whether the horizontality and the pressure are normal by comparing the color average value by each block and the color average value

Description

Inspection method for horizontality and pressure of collet}

The present invention relates to a method for checking the level and pressure of the collet, in particular through the analysis of the image of the shape of the collet pressed on the pressure-sensitive paper automatically measuring the level and pressure of the collet and the level of the collet that can determine whether or not defective And a pressure test method.

In general, the post-semiconductor process is largely a wafer inspection process for inspecting the quality of semiconductor chips formed on a wafer, sawing for cutting the wafer, and bonding the cut semiconductor chips to a PCB substrate having a lead frame. Die bonding process, wire bonding process that connects the pads of the semiconductor chip and the lead of the lead frame with wires, and encapsulation material to protect the internal circuit and other components of the semiconductor chip. Molding process for molding the outside, trimming process for cutting the dam bar connecting the lead of the molded lead frame, forming process for bending the lead to the desired shape, and completed through the above process And a test process for inspecting the quality of the semiconductor device.

Meanwhile, in the die bonding process, the semiconductor chip on the wafer stage is picked up using a pickup device having a collet at the bottom, and transferred to the bonding stage on which the PCB substrate is placed, and then bonded to the PCB substrate. The bottom of the collet will wear out and not be able to maintain flatness, thus resulting in an uneven level. As such, when the collet is not horizontally aligned, when the collet is worn out, or when the adhesion pressure is uneven, pick-up failure or die bonding failure that does not pick up chips accurately occurs.

 This die bonding failure not only causes problems such as chip breakage during the molding process, which is a subsequent process, but also reduces the yield because it is impossible to know exactly when pick-up failure occurs if the horizontal and pressure changes of the collet are not continuously monitored. Can cause.

In the related art, the operator periodically checks the level and pressure of the collet periodically. That is, the operator uses a pressure-sensitive paper, which is a paper for measuring pressure and level, to measure the level and pressure state of the collet. This method allows the pressure-sensitive paper to be pressurized at the set pressure, and visually inspects the pressurized state. By determining whether or not the collet is paid.

However, since such an inspection method is arbitrarily performed by an operator, there is a lack of an accurate criterion for determining whether there is no accurate judgment of the inspection, which makes it difficult to systematically manage the process.

As a technique for solving the problem of the manner in which the operator checks the pressure-sensitive paper through the naked eye, there is a case where a horizontal indicator for indicating the inclination of the collet in Korea Laid-Open Patent No. 2008-0007716.

However, according to Korean Patent Laid-Open Publication No. 2008-0007716, the horizontality of the collet can be confirmed through a horizontal indicator, but it is difficult to verify the case of poor pressure.

In addition, in recent years, a stacked wafer has been used as the thickness of the wafer decreases. If the uniformity is not applied to the surface of the semiconductor chip due to poor level of the collet, or the pressure is low, the collet cannot adsorb the semiconductor chip normally. Problems will arise. In addition, when the pressure is too high, there is a problem that damage may occur because the wafer is thin.

As such, the bad collet horizontality and pressure state of the bonding equipment are becoming more and more problematic as the thickness of the wafer is reduced.

An object of the present invention for solving the problems of the prior art is to use the color information of the stamp image stamped on the pressure-sensitive paper collet level and pressure inspection to automatically check for the defect of the level or wear and pressure of the collet In providing a method.

The horizontal and pressure inspection method of the collet of the present invention for solving the problem comprises a first step of obtaining image information of the pressure-sensitive paper having a plurality of stamp images corresponding to the collet shape, each one stamp in the pressure-sensitive paper image A second step of setting a plurality of unit inspection areas so as to divide each unit inspection area into a plurality of block units, a fourth step of calculating a color average value of each block and a unit inspection area, and a color average value of each block and each And a fifth step of determining whether the horizontality and the pressure are normal by comparing the color average value of the unit inspection area with a setting criterion.

Here, in the fifth step, it may be determined that the horizontality is poor when the difference between the color average values of the respective blocks is greater than or equal to the reference set difference, and that the pressure is bad when the color average value of the unit inspection area is less than or equal to the reference average value.

In addition, the second step may include scanning the pressure-sensitive paper image to search for areas in which colors are dense, and setting a plurality of unit inspection areas based on a preset collet shape for the color dense areas. .

Alternatively, the second step may be a step of scanning a point where color detection is started by scanning a line in a first direction with respect to at least two arbitrary points on one side of the pressure sensitive image, and at least two arbitrary on the other side of the pressure sensitive image. Searching for a point where color detection starts by performing a line scan in a second direction opposite to the first direction with respect to the point of, and a first passing through at least two color detection start points found by the first direction line scan. Generating a line reference line, generating a second line reference line passing through at least two color detection start points discovered by the second directional line scan, and performing an image scan on the area between the first reference line and the second reference line. And setting a plurality of unit inspection regions based on a collet shape preset for the scan region. can do.

Alternatively, the second step may include generating one scan area including a plurality of stamps on the pressure-sensitive paper image, performing an image scan on the inside of the scan area, and based on a preset collet shape for the scan area. And generating a plurality of unit inspection regions.

The plurality of inspection areas may be set through pattern matching with a shape of a preset collet, or the inspection area may be divided into the same size based on a predetermined collet shape and interval information between stamps.

Also, after setting the plurality of inspection areas, performing edge detection of the stamp along the edge direction of the unit inspection area from the center position in each unit inspection area, and unit inspection area such that the edge of the stamp is located inside the unit inspection area. The method may further include correcting the position of the.

In addition, the plurality of inspection region setting steps may include generating a plurality of unit inspection regions corresponding to a preset standard collet shape, and edges of the stamp along the edge direction of the unit inspection region starting from a center position in each unit inspection region. The method may further include performing detection, and correcting the position and size of the unit inspection region such that the edge of the stamp is located inside the unit inspection region.

In addition, the plurality of inspection region setting steps may include generating a plurality of unit inspection regions corresponding to a preset standard collet shape, and comparing the stamp edges and the standard collet shapes in the plurality of unit inspection regions to shape the collet corresponding to the stamp. Automatically extracting the information, resetting a plurality of unit inspection areas corresponding to the extracted collet shape, and starting the center position within each reset unit inspection area along the edge direction of the unit inspection area. The method may further include performing edge detection, and correcting the position and size of the unit inspection region such that the edge of the stamp is located inside the unit inspection region.

Alternatively, the second step may include setting a plurality of window positions so that each stamp is located inside the window according to a user manipulation signal, and setting a plurality of unit inspection areas by scanning each window inner area. .

The present invention has the advantage that the reliability of inspection is improved by applying the automatic inspection method, not the visual inspection method by the operator, by determining the level of the collet, the wear state and the pressure state defect only through the stamp image color information.

In addition, the present invention has the advantage that it is possible to reduce the inspection speed as it is possible to simultaneously measure the horizontal and pressure state of the collet.

1 is a block diagram of a horizontal and pressure measurement system of a collet according to an embodiment of the present invention.
2 is a flow chart showing a collet horizontality and pressure measuring method according to an embodiment of the present invention.
3A to 3E are reference views for explaining a collet horizontality and a pressure measuring method according to an exemplary embodiment of the present invention.
4 to 10 are various exemplary views for describing in detail the plurality of inspection area setting steps of FIG. 2.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a horizontal and pressure measuring system configuration of a collet according to an embodiment of the present invention, Figure 2 is a flow chart showing a horizontal and pressure measuring method of a collet according to an embodiment of the present invention, Figures 3a to 3c Reference diagram for explaining the collet horizontality and pressure measuring method according to an embodiment of the present invention.

The horizontal and pressure measuring system of the collet according to the invention comprises a camera 20 and a control computer 30 as shown in FIG.

Here, the camera 20 photographs a plurality of stamps 11 images imprinted on the pressure-sensitive paper 10, and transfers the photographed images to the control computer. At this time, the plurality of stamps 11 stamped on the pressure-sensitive paper 10 is formed by pressing the pressure-sensitive paper in accordance with the predetermined interval conditions.

The control computer 30 analyzes the stamp image acquired through the camera 10 to determine whether the collet is defective in the horizontal and pressure state, and controls the driving of the die bonding equipment 40 based on the determination result. It serves to deliver to the process management server (50).

Here, the control computer 30 includes an image processor 31, an image analyzer 32, a drive controller 33, and a database 40.

The image processor 31 scans a predetermined region of the image input through the camera 20 to calculate a color average value for each inspection region, and the image analyzer 32 is acquired through the image processor 31. The average color value is used to determine whether the collet is flat or the pressure is bad.

The driving controller 33 controls the driving of the die bonding equipment 40 according to a camera 20 control signal or an image analysis result such as zoom magnification or exposure control.

In the database 34, criteria for color average values for determining the horizontality of the collet and the failure of the pressure state are set, and the shape information of the collet corresponds to the collet identification information, for example, identification information such as a barcode attached to the collet. It is registered, the shape information of the most commonly used standard collet can be registered irrespective of the collet identification information.

Hereinafter, the horizontal and pressure test method of the collet according to the present invention will be described with reference to FIGS. 1 and 2.

First, the pressure-sensitive paper 10 is photographed by controlling the zoom magnification or exposure of the camera 20, so as to obtain the pressure-sensitive paper image 100 having the plurality of stamps 110 images as shown in FIG. 3C (S10). ).

In operation S11, a plurality of unit inspection areas are set in the acquired image. In this case, each of the plurality of unit inspection areas A will be described in detail with reference to FIGS. 4 to 10, which will be described later in detail with respect to a method of setting the plurality of unit inspection areas A as an inspection area.

Subsequently, as illustrated in FIG. 3C, each unit inspection area A is divided into a plurality of blocks B in a matrix form (S12), and the color average value of each block (B) and each unit inspection area (A) is determined. To calculate (S13).

Then, the color average value of each block and the color average value of each unit inspection area are compared with the setting criteria registered in the database to determine whether the horizontality and the pressure are normal (S14).

Here, the horizontality of the collet is determined to be poor when the difference in the average color value of each block is larger than the reference set difference. That is, when the level of collet is normal or the wear state of the collet is good, the area where the collet touches the decompression paper or the height of the collet are constant. Therefore, as shown in FIG. 3C, each block B divided into nine segments is shown. The difference in the mean values for the red color of the stamp is within a certain range.

However, when the collet has a poor level or wear condition, the area where the collet touches the decompression paper and the height of the collet are not constant. As shown in FIG. That is, the color difference between the "B1" block where the collet touches first and the "B2" block where the collet touches or hardly touches later occurs, so that the color average value of the "B1" block and the color average value of the "B2" block In this case, it is determined that the flatness or wear state of the collet is poor.

 Further, the pressure state of the collet is determined to be normal when the color average value of the unit inspection area A is equal to or greater than the reference average value, and defective when it is less than or equal to the reference average value. That is, when the pressure of the collet is normal, as shown in FIG. 3C, the stamp image appears clearly, but when the pressure of the collet is poor, it can be seen that the color of the stamp is blurred. That is, the color average value of the unit inspection area A in the steady state is equal to or greater than the reference average value, but the color average value of the unit inspection area B in the defective state is equal to or less than the reference average value.

As such, the present invention automatically improves inspection reliability and reduces defect rate by automatically determining whether the collet is flat and whether the level of wear or pressure is poor by using the color average value of the stamp stamped on the pressure-sensitive paper instead of the operator's visual inspection. .

Hereinafter, various embodiments of the method for setting the plurality of unit inspection areas A will be described with reference to FIGS. 4 to 10.

First, as illustrated in FIGS. 4 and 5, a plurality of unit inspection areas may be set by manually specifying a scan area and performing an image scan only on the designated area.

First, FIG. 4 relates to a method in which a user directly designates a plurality of scan areas corresponding to each stamp. As shown in FIG. The image is displayed on the screen together with the image, and the user moves the window position to correspond to the image of each stamp as shown in FIG. When the window is assigned to each stamp for all stamps by repeating the window position shifting process, as shown in FIG. Set. In this case, in FIG. 4, when the set window is displayed on the screen, the user moves the window to designate the scan area, but the user adjusts the position and size of the scan area by using a mouse operation without a separate window. You can also apply

As described above, the method of designating the scan area and setting the plurality of unit inspection areas by user manipulation may reduce the accuracy of setting the unit inspection area due to a user's operation error. Therefore, when the edge detection of the unit inspection area occurs by executing the stamp edge detection in the set unit inspection area, it can be automatically corrected. Such an edge detection method will be described in detail in the following embodiments.

FIG. 5 is a method of directly setting one scan area including a plurality of stamps. As shown in FIG. 5A, a pressure-sensitive paper image 100 is displayed on a screen, and a user performs a mouse operation. The scan area 200 may be designated through the scan area 200.

Subsequently, as illustrated in (b) of FIG. 5, an image scan is performed on the scan area 200 designated by a user operation, and the pattern area or the same size division method is applied to the scan area 200. As shown in (c), the plurality of unit inspection areas 130 are set. Here, the unit inspection area 130 may search for the stamp image in the scan area 200 through pattern matching with a preset collet shape or scan area 200 based on interval information between the preset collet shape and the stamp. May be used to divide and set the same size.

4 and 5 described above, the user's operation is required to designate the scan area, but the scan time is not limited to scanning the entire pressure-sensitive paper image, so only a narrow range where the stamp is located is required for scanning. There is an advantage that can be shortened.

6 to 10 are exemplary embodiments illustrating a method of automatically setting a plurality of unit inspection areas without an operation by a user.

Referring to FIG. 6, first, the entire area of the pressure-sensitive paper image 100 input through the camera is scanned as shown in FIG. 6A, and within the scanned image as shown in FIG. 6B. The area 300 where the colors are concentrated is searched.

As illustrated in FIG. 6C, a plurality of unit inspection regions 130 are set based on a collet shape preset for the color dense region 300.

Here, the unit inspection area 130 finds the stamp image in the color dense area through pattern matching with the preset collet shape, or sets the color dense area to the same size based on the preset collet shape and the interval information on which the stamp is stamped. The division setting method may be used.

However, when the scan is performed on the entire pressure-sensitive paper image in this way, it takes a long time.

Accordingly, a method of scanning only the stamped region may be performed as shown in FIG. 7 without scanning the entire pressure-sensitive paper image.

Referring to FIG. 7, first, at least two arbitrary points are selected on one side of the pressure sensitive image 100 as shown in FIG. 7A, and a line scan is performed in the first direction from the selected points. The color detection starting points 400 and 410 are searched at the edge of. When at least two random points are selected on the other side of the pressure-sensitive paper image and the line scan is performed in the second direction opposite to the first direction, the color detection starting points 420 and 430 are searched at the edges of the stamp image.

When the color detection start point is searched by performing the line scan, the first reference line 440 and the second reference line passing through the two points 400 and 410 searched by the first direction line scan as shown in (b) of FIG. 7. Create a second reference line 450 passing through two points 420 and 430 found by the directional line scan.

As shown in (c) of FIG. 7, an image scan is performed only on the region 460 between the first reference line and the second reference line, and as illustrated in (d) of FIG. 7 for the scan region 260. As such, a plurality of unit inspection areas 130 are set.

In this case, the unit inspection area 130 may search for the stamp image in the scan area 260 through pattern matching with the preset collet shape in the same manner as in FIG. 5, or the interval information between the preset collet shape and the stamp. Based on the method, the scan area 270 may be divided and set to the same size.

On the other hand, when the above-described unit inspection area is set, the pattern matching accuracy may be reduced, or in the case of dividing the color dense area or the scan area into the same size, the inspection area setting accuracy may be low and the reliability of the test may be deteriorated.

That is, as shown in (a) of FIG. 8, when the unit inspection area 130 is set to be offset from the edge of the stamp image 110, a method of correcting the unit inspection area by detecting the unit inspection area and the edge of the stamp image is described. Applicable

Specifically, edge detection of the stamp is performed along the edge direction of the unit inspection area from the center position in the unit inspection area set as shown in Fig. 8B.

Here, the edge detection is generated as a histogram which is a distribution value of light and dark values for pixels in the left and right direction from the center position, and when the distributions of the two histograms generated based on the center position are different (sizes of E1 and E2). Is different) automatically corrects the position of the unit inspection region until the positions of both histograms are the same, that is, the stamp image is located inside the unit inspection region.

In this case, although the edge detection is performed only in the X-axis direction, the edge detection and the unit inspection area position correction are also performed in the Y-axis direction.

Meanwhile, the above-described embodiments of the present invention register the collet shape in advance in the database corresponding to the barcode identification number attached to each collet, and extract and use the collet shape information by identifying the barcode attached to the collet every inspection.

The method of extracting the collet shape information by identifying the barcode attached to the collet is cumbersome for the user to manually identify the barcode, and there is a problem that the inspection is impossible when the barcode is difficult to recognize.

9 and 10 are to solve the shortcomings of the method for checking the collet horizontality and pressure state using the bar code information described above, and to determine the horizontality and pressure state of the collet using shape information corresponding to the standard collet without identifying the barcode. How to check.

First, as shown in Fig. 9A, the standard collet shape 600 information is registered in advance in the database.

As shown in FIG. 9B, a plurality of unit inspection areas 130 corresponding to standard collet shape information are set, and as shown in FIG. 9C, the edge direction of the unit inspection area 130 is set. Accordingly, edge detection of the stamp image is performed.

At this time, since the standard collet shape is different from the stamp shape of the collet being actually inspected, the position and size of the unit inspection area do not coincide with the stamp image 110.

Therefore, the present invention automatically corrects the position and size of the unit inspection area so that the edge of the image of the stamp is located inside the unit inspection area, thereby creating the final unit inspection area 130 as shown in FIG. At this time, the edge detection method is the same as the description of the above (b) of Figure 8 will be omitted a detailed description thereof.

Alternatively, the present invention stores a standard collet shape 500 as shown in FIG. 10 (a), a plurality of collet shape 600 images corresponding to actual collets, and as shown in FIG. 10 (b). It registers in advance in the type information database which can classify a collet shape automatically according to the matching degree of the histogram distribution value of a standard collet shape, and the histogram distribution form of a collet shape.

For example, as illustrated in FIG. 10C, a plurality of unit inspection areas 610 corresponding to the standard collet shape 600 are set. At this time, since the standard collet shape is different from the stamp shape of the collet being actually inspected, the position and size of the unit inspection area do not coincide with the stamp image 110.

Accordingly, the histogram distribution detected for edge detection of the stamp image, that is, histogram distribution along the edge direction of the unit inspection area 610 is different from the registered histogram distribution as shown in FIG. The shape information of the actual collet is automatically extracted according to the degree of matching with the histogram distribution corresponding to the shape.

As shown in FIG. 9D, the plurality of unit inspection areas 130 corresponding to the extracted actual collet shape information are reset, and the unit is set based on the center position in each of the reset unit inspection areas as described above. Edge detection of the stamp is performed along the edge direction of the inspection area, so that the position and size of the unit inspection area are corrected so that the edge of the stamp is located inside the unit inspection area.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. Accordingly, the appended claims are intended to cover such modifications or changes as fall within the scope of the invention.

100: pressure-sensitive paper image 110: stamp image
130: unit inspection area

Claims (10)

A first step of obtaining image information of the pressure-sensitive paper having a plurality of stamp images corresponding to the collet shape;
A second step of setting a plurality of unit inspection areas to each include one stamp in the pressure-sensitive paper image;
Dividing the unit inspection area into a plurality of block units;
A fourth step of calculating a color average value of each block and unit inspection area;
And a fifth step of determining whether the level and pressure are normal by comparing the color average value of each block and the color average value of each unit inspection area with a setting criterion.
The method of claim 1,
In the fifth step,
When the difference in the color average value of each block is more than the reference set difference, it is determined that the degree of poorness, and when the color average value of the unit inspection area is less than the reference average value, it is determined that the pressure is poor, the horizontal and pressure test method of the collet .
The method of claim 1,
The second step
Scanning the pressure-sensitive paper image to search for areas of dense color;
And setting a plurality of unit inspection areas based on a preset collet shape with respect to the color dense area.
The method of claim 1,
The second step,
Searching for a point where color detection is started by line scanning each of at least two arbitrary points on one side of the pressure-sensitive paper image in a first direction;
Searching for a point at which color detection starts by performing a line scan on at least two arbitrary points on the other side of the pressure-sensitive paper image in a second direction opposite to the first direction;
Generating a first line reference line passing through at least two color detection start points searched by the first directional line scan;
Generating a second line reference line passing through at least two color detection start points searched by the second directional line scan;
Performing an image scan on an area between the first reference line and the second reference line, and
And setting a plurality of unit inspection areas based on a preset collet shape of the scan area.
The method of claim 1,
The second step,
Generating a scan area including a plurality of stamps on the pressure-sensitive paper image;
Performing an image scan of the inside of the scan area;
And generating a plurality of unit inspection regions based on a preset collet shape with respect to the scan region.
6. The method according to any one of claims 1 to 5,
The plurality of inspection areas may be set through pattern matching with a shape of a preset collet, or the inspection area may be divided into the same size based on a predetermined collet shape and interval information between stamps. Degree and pressure checking method.
The method according to claim 6,
Performing edge detection of the stamp along the edge direction of the unit inspection region starting from the center position in each unit inspection region after setting the plurality of unit inspection regions;
Correcting the position of the unit inspection region such that the edge of the stamp is located inside the unit inspection region.
The method according to claim 6,
The plurality of inspection area setting steps may include
Generating a plurality of unit inspection regions corresponding to a preset standard collet shape;
Performing edge detection of the stamp along the edge direction of the unit inspection area from the center position in each unit inspection area;
And correcting the position and size of the unit inspection area so that the edge of the stamp is located inside the unit inspection area.
The method according to claim 6,
The plurality of inspection area setting steps may include
Generating a plurality of unit inspection regions corresponding to a preset standard collet shape;
Automatically extracting shape information of a collet corresponding to the stamp by comparing stamp edges in the plurality of unit inspection areas with the standard collet shape;
Resetting a plurality of unit inspection areas corresponding to the extracted collets;
Performing edge detection of the stamp along the edge direction of the unit inspection area from the center position in each of the reset unit inspection areas;
And correcting the position and size of the unit inspection area so that the edge of the stamp is located inside the unit inspection area.
The method of claim 1,
The second step
Setting a plurality of window positions such that each stamp is located inside the window according to a user manipulation signal;
And scanning a plurality of unit inspection areas by scanning the inner region of each window.

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