JP2004014693A - Method for detecting alignment mark position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detecting method for an alignment mark, which can detect the accurate position of the alignment mark by solving the problem of aberrations of a camera lens. <P>SOLUTION: The position of the alignment mark M is detected by first imaging by a camera member, and the relative positions of the camera member and a work are adjusted based upon the detected value of the position of the center Om of the alignment mark M which is detected for the first time in such a direction that a center Om' of the alignment mark M of the work is disposed on the center line of the camera lens of the camera member. After this adjustment, imaging by the camera member is carried out again to detect the center position Om' of the alignment mark M. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for detecting the position of an alignment mark for positioning when two workpieces are joined.
[0002]
[Problems to be solved by the invention]
In general, when electronic components such as TCP (Tape Carrier Package), FPC (Flexible Printed Circuit), and IC (Integrated Circuit) are mounted on a circuit board or the like, the position of an alignment mark displayed on each is detected. The electronic component and the circuit board are aligned with each other so that the alignment marks whose positions have been detected overlap each other.
[0003]
Then, by positioning the electronic component and the circuit board with each other by detecting the position of the alignment mark, the external connection terminals formed on the both are aligned with each other, and the external connection terminals whose correspondence is set in advance are set. The connection terminals are connected.
[0004]
The position of the alignment mark is detected by imaging the alignment mark with a CCD camera or the like and calculating the center position of the alignment mark by image analysis based on image data obtained by the imaging.
[0005]
FIG. 6 is an image explanatory view showing a conventional method for detecting the position of the alignment mark.
In FIG. 6, P indicates an image obtained by capturing a portion of the work, such as an electronic component or a circuit board, on which the alignment mark M is displayed by a CCD camera. In the drawing, Op indicates the image origin of the image P. Om indicates the center of the alignment mark M located in the image P.
[0006]
In a conventional method for detecting the position of an alignment mark, a control device such as a microcomputer for detecting the position of the alignment mark uses an alignment mark M within an angle of view of a CCD camera such as an image P shown in FIG. When the image data of the workpiece surface where is located is obtained, the coordinate position of the center Om of the alignment mark M in the image P is detected by performing image analysis based on the image data.
[0007]
Then, the coordinate position of the center Om of the alignment mark M is compared with the coordinate position of the image origin Op of the image P, and the shift amount (ΔX, ΔY) between the center Om and the image origin Op is calculated. Do.
[0008]
The data of the deviation amount (ΔX, ΔY) between the center Om and the image origin Op thus calculated is used as a correction value at the time of alignment of the alignment mark M, and this deviation amount (ΔX , ΔY), the alignment of the alignment mark M is performed.
[0009]
However, in the above-described method for detecting the position of the alignment mark, the position of the alignment mark M is located at the corner of the angle of view of the CCD camera, that is, the position distant from the image origin Op in the image P by the CCD camera. , The error generated in the detected value of the position of the center Om of the detected alignment mark M increases due to the aberration of the camera lens of the CCD camera.
[0010]
For this reason, the conventional alignment mark position detection method may not be able to accurately align the alignment marks, and in particular, a few microns may be caused by joining each other like an electronic component and a circuit board. In the case where the connection of the external connection terminals arranged in units is performed, due to an error in the detected value of the detected center position of the alignment mark, the connection between the set corresponding external connection terminals is not performed, There is a problem that defective products are generated.
[0011]
The present invention has been made to solve the problems in the conventional alignment mark position detection method as described above.
[0012]
That is, the present invention solves the problem of aberration in the camera lens of the camera member that takes an image of the alignment mark when detecting the position of the alignment mark displayed on the workpiece, and corrects the position of the alignment mark. It is an object of the present invention to provide a position detection method capable of performing detection.
[0013]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for detecting the position of an alignment mark displayed on a workpiece by imaging with a camera member. An image of the portion where the mark is displayed is taken, the first detection of the center position of the alignment mark is performed, and the camera member and the workpiece are detected based on the detected value of the center position of the alignment mark detected first. The relative position is adjusted so that the center of the alignment mark of the workpiece is positioned on the center line of the camera lens of the camera member, and after the first adjustment, the alignment mark of the workpiece by the camera member is displayed. The center position of the alignment mark must be detected again by It is characterized in.
[0014]
According to the alignment mark position detecting method according to the first aspect of the present invention, first, a work such as an electronic component or a circuit board for performing position detection is performed such that the alignment mark falls within the angle of view of a camera member such as a CCD camera. After this, the camera member performs the first imaging of the portion of the work where the alignment mark is displayed.
[0015]
After the first imaging, the center position of the alignment mark is detected by image analysis by a control device such as a microcomputer connected to the camera member.
[0016]
Then, based on the detected value of the center position of the alignment mark by the first imaging, for example, based on the calculated value of the shift amount between the detected center position of the alignment mark and the image origin of the captured image, The relative position of the workpiece is adjusted in a direction in which the center of the alignment mark coincides with the image origin of the captured image, that is, in a direction in which the center of the alignment mark is located on the center line of the camera lens of the camera member. .
[0017]
After this first position adjustment, a second imaging of the portion where the alignment mark of the work is displayed by the camera member is performed, and the center position of the alignment mark is set in the same manner as in the first imaging. Detection is performed.
[0018]
In this way, the position of the work is adjusted based on the detected value of the center position of the alignment mark obtained by the first imaging, and the alignment mark is positioned substantially on the center line of the camera lens of the camera member. Since the position of the center position of the alignment mark is detected by performing imaging again, the center of the alignment mark is located at the corner of the angle of view of the camera member at the time of the first imaging, and the camera lens Even if an error occurs in the detected value of the detected center position of the alignment mark due to the aberration, the influence of the aberration of the camera lens can be almost canceled by the second imaging, and the accurate The position of the center of the alignment mark can be detected.
[0019]
In order to achieve the above object, an alignment mark position detecting method according to a second aspect of the present invention, in addition to the configuration of the first aspect, uses the camera member again after the first adjustment of the relative position between the camera member and the workpiece. It is characterized in that the imaging and the re-adjustment of the relative position between the camera member and the work based on the detected value of the center position of the alignment mark by the re-imaging are performed at least once.
[0020]
According to the alignment mark position detecting method according to the second invention, after the position adjustment of the work based on the first image pickup, the center position of the alignment mark is detected by the second image pickup. If an error occurs in the detected value of the alignment mark position even when the position is detected by the imaging of the above, the same operation is repeated to perform the position detection by the imaging again, thereby achieving perfect alignment of the workpiece. Done.
[0021]
In order to achieve the above object, an alignment mark position detecting method according to a third aspect of the present invention, in addition to the configuration of the first aspect, detects the position of each alignment mark displayed on two works joined to each other. When performing the above, the portions where the respective alignment marks of the two workpieces are displayed are located at positions where joining is performed, and the first imaging by the camera member and the alignment and the alignment detected by the first imaging are performed. Adjustment of the relative position of the camera member and the work based on the detected value of the center position of the mark, and detection of the center position of the alignment mark by re-imaging with the camera member after the adjustment of the relative position of the camera member and the work It is characterized by performing.
[0022]
According to the alignment mark position detecting method according to the third aspect of the present invention, the two marks are displayed on two works joined to each other by the alignment mark, such as a circuit board and an electronic component such as a TCP or an FPC. The position detection of each alignment mark is performed under the same conditions at the actual joining position of the two works.
[0023]
As a result, it is possible to prevent an error from occurring when the workpiece is moved from the position where the position of the alignment mark is detected to the position where the joining is actually performed.
[0024]
The detection of the center position of the alignment mark at the joint position of the work is performed based on the detected value of the center position of the alignment mark obtained by the first imaging, and the position of the work is adjusted. An image is taken again in a state where the member is positioned substantially on the center line of the camera lens, and the position of the center position of the alignment mark is detected, so that very accurate position detection can be performed. become.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the most preferred embodiment of the present invention will be described in detail with reference to the drawings.
[0026]
Note that the present invention can be applied to the detection of the position of an alignment mark for any workpiece that is aligned with each other using an alignment mark. In the following, electronic components such as TCP, FPC, and IC are used. The description will be made by taking as an example the detection of the position of an alignment mark when bonding to a glass substrate of an LCD (Liquid Crystal Display).
[0027]
FIGS. 1 and 2 are side sectional views showing an example of an alignment mark position detecting device in which a method for detecting the position of an alignment mark according to the present invention is performed. FIG. FIG. 2 shows a position detection state for the alignment mark on the TCP side.
[0028]
In FIG. 1, a support table S for holding a portion of the glass substrate B on which the alignment mark M1 is displayed is formed of, for example, a transparent material such as glass. The alignment mark M1 of the glass substrate B held on S can be recognized through the glass substrate B.
[0029]
FIG. 3 shows an example of the alignment mark M1 displayed on the glass substrate B.
[0030]
Then, a CCD camera C is disposed below the support table S.
The transfer table T for transferring the glass substrate B onto the support table S retracts the portion of the glass substrate B on which the alignment mark M1 is displayed from the position on the support table S and from the support table S. It is configured to be able to advance and retreat with respect to the support table S so as to slide between the positions.
[0031]
The mounting head H holding the electronic component E on which the alignment mark M2 is displayed has separated the electronic component E from the mounting position on the glass substrate B on the support table S and from the mounting position above the support table S. It is configured to be able to move up and down so as to move up and down between the positions.
[0032]
An XY robot (not shown) is connected to the mounting head H. The XY robot can slide the held electronic component E in two directions orthogonal to each other in a horizontal plane. ing.
[0033]
FIG. 4 shows an example of the alignment mark M2 displayed on the electronic component E.
[0034]
In the alignment mark position detecting device, when the position of the alignment mark is detected, first, as shown in FIG. 1, a portion of the glass substrate B held by the transfer table T on which the alignment mark M1 is displayed. Is positioned on and supported by the support table S, and is displayed on the upper surface side of the glass substrate B through the support table S and the glass substrate B by the CCD camera C disposed below the support table S. The imaging of the alignment mark M1 is performed.
[0035]
The position data of the center Om1 (see FIG. 3) of the alignment mark M1 is detected by image analysis of the image data of the alignment mark M1 by a control device (not shown) such as a microcomputer connected to the CCD camera C. Is done.
A method of detecting the position data of the center Om1 of the alignment mark M1 at this time will be described later in detail.
[0036]
Next, as shown in FIG. 2, after the position of the center Om1 of the alignment mark M1 is detected, the transport table T is retracted, and the display portion of the alignment mark M1 on the glass substrate B is moved from above the support table S. Be evacuated.
[0037]
Thereafter, the mounting head H is lowered, and the portion of the lower surface of the electronic component E held by the mounting head H, on which the alignment mark M2 is displayed, is held on the support base S by the glass substrate B. It stops at the position where it is positioned at the same height as the position of the upper surface of the glass substrate B at that time.
[0038]
After that, the alignment mark M2 of the electronic component E held by the mounting head H is imaged by the CCD camera C through the support base S, and the CCD camera C is moved in the same manner as in the case of detecting the position of the alignment mark M1. The control device (not shown) analyzes the image data obtained by the image pickup by the camera, and thereby, the center Om2 of the alignment mark M2 at the joint position of the electronic component E with the glass substrate B on the support base S (see FIG. 4) ) Is detected.
A method of detecting the position data of the center Om2 of the alignment mark M2 at this time will be described later in detail.
[0039]
When the control device detects the respective position data of the center Om1 of the alignment mark M1 and the center Om2 of the alignment mark M2 as described above, the control device compares the respective position data, and based on the comparison result, determines the mounting head. By controlling the driving of the XY robot connected to H, the mounting head H holding the electronic component E at the mounting height on the glass substrate B is aligned with the center Om1 of the detected alignment mark M1. Slide the mark M2 in the horizontal direction by the amount of shift of the center Om2.
[0040]
In this way, the electronic component E held by the mounting head H is positioned at a position where the center Om2 of the alignment mark M2 matches the position of the center Om1 of the alignment mark M1 detected earlier. Then, thereafter, the mounting head H is raised, and the electronic component E is temporarily evacuated from its mounting position on the glass substrate B.
[0041]
When the transfer table T is moved forward, the portion of the glass substrate B held on the transfer table T where the alignment mark M1 is displayed is positioned and supported on the support table S. Thereafter, the mounting head H is lowered again, and the electronic component E held by the mounting head H is joined to the upper surface of the glass substrate B held on the support table S.
[0042]
At this time, when the position of the alignment mark M2 is detected, the position of the center Om2 of the alignment mark M2 is changed to the position of the support table when the electronic component E has been lowered to the mounting position on the glass substrate B with the lowering of the mounting head H. Since the position is adjusted so as to coincide with the position of the center Om1 of the alignment mark M1 of the glass substrate B on S, the glass substrate B is accurately bonded to a predetermined bonding position on the glass substrate B on the support base S. You.
[0043]
Since the position of the alignment mark M2 of the electronic component E is detected at the actual bonding position to the glass substrate B, the alignment mark position detecting device detects the position of the alignment mark M2 on the glass substrate B. An error occurs when an electronic component is moved from a position where the alignment mark position is detected to a position where the electronic component is actually mounted on a circuit board, such as in a case where the electronic component is moved away from a bonding position. There is no risk of such a problem.
[0044]
Next, a method of detecting the positions of the center Om1 of the alignment mark M1 and the center Om2 of the alignment mark M2 will be described.
Since the method of detecting the positions of the alignment marks M1 and M2 is the same, the method of detecting the position of the alignment mark M will be described together.
[0045]
In the method of detecting the position of the alignment mark M, first, a workpiece such as an electronic component or a circuit board whose position is to be detected is roughly positioned so that the alignment mark M falls within the angle of view of the CCD camera. The camera C performs the first imaging of a portion of the work where the alignment mark M is displayed.
[0046]
FIG. 5A shows an image captured by the CCD camera C at this time.
FIG. 5A is an image similar to that of FIG. 6 described above, and shows an image obtained by capturing a portion of a work such as an electronic component or a circuit board on which an alignment mark M is displayed by a CCD camera. The same reference numerals as in FIG. 6 are used.
[0047]
After the first imaging, a control device such as a microcomputer connected to the CCD camera performs image analysis based on the image data of the image P, and coordinates of the center Om of the alignment mark M in the image P. Perform position detection.
Then, the shift amount (ΔX, ΔY) of the center Om of the alignment mark M with respect to the image origin Op of the image P is calculated.
[0048]
Then, based on the data of the deviation amount (ΔX, ΔY) between the center Om and the image origin Op obtained in this way, the workpiece is moved by this deviation amount (ΔX, ΔY), whereby the alignment Positioning is performed so that the center Om of the mark M coincides with the image origin Op of the image P, that is, on the center line of the camera lens of the CCD camera.
Then, in this state, the second imaging is performed by the CCD camera.
[0049]
FIG. 5B shows an image obtained by the second imaging.
Here, at the time of the first imaging, when the center Om of the alignment mark M is imaged at a position away from the image origin Op of the image P, that is, at the corner of the angle of view of the CCD camera, In some cases, an error occurs in the detected value of the center Om of the detected alignment mark M due to the aberration of the camera lens.
[0050]
For this reason, as shown in FIG. 5B, based on the position data of the center Om of the alignment mark M detected by the first imaging, the center Om of the alignment mark M is moved to the image P. , The position between the center Om of the alignment mark M and the image origin Op of the image P due to a position detection error at the time of the first imaging. appear.
[0051]
For this reason, a control device such as a microcomputer connected to the CCD camera re-analyzes the image based on the image data of the image P ′, and determines the coordinate position of the center Om ′ of the alignment mark M in the image P ′. Perform detection.
Then, the shift amount (ΔX ′, ΔY ′) of the center Om ′ of the alignment mark M with respect to the image origin Op ′ of the image P ′ is calculated.
[0052]
The coordinate position of the center Om ′ of the alignment mark M detected by the second imaging is determined by aligning the work based on the first imaging with the alignment mark M in the image P ′. , The detection error due to the aberration of the camera lens hardly occurs, or even if it occurs, it is negligibly small.
[0053]
Therefore, the workpiece is moved by the amount of displacement (ΔX ′, ΔY ′) between the center Om ′ of the alignment mark M and the image origin Op ′ of the image P ′ calculated based on the detection result of the second imaging. By re-adjusting the position, the center Om 'of the alignment mark M can be almost completely matched with the image origin Op' of the image P '.
[0054]
If an error occurs in the detected value of the alignment mark position even in the position detection by the second imaging, the work is performed by repeating the same operation to perform the imaging again to detect the position. Almost perfect alignment will be possible.
[0055]
As described above, the alignment mark position detection method can perform extremely accurate position detection as compared with the conventional method when detecting the position of the alignment mark for aligning the workpiece. The present invention can also be applied to position detection for alignment performed in units of several microns.
[0056]
When used in combination with the alignment / mark position detecting device as shown in FIGS. 1 and 2, position detection with higher accuracy can be performed.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of an alignment mark position detecting device in which an alignment mark position detecting method according to the present invention is performed, in a state where the position of an alignment mark on a glass substrate is detected.
FIG. 2 is a side view showing the alignment mark position detection device of the same example in a state where the position of the alignment mark of the electronic component is detected.
FIG. 3 is a plan view showing an example of an alignment mark displayed on a glass substrate.
FIG. 4 is a plan view illustrating an example of an alignment mark displayed on the electronic component.
FIG. 5A is an explanatory diagram showing an image obtained by first imaging in an example of an embodiment of an alignment mark position detecting method according to the present invention, and FIG. It is explanatory drawing which shows an image.
FIG. 6 is an explanatory diagram showing a captured image in a conventional alignment mark position detection method.
[Explanation of symbols]
B: Glass substrate (work)
C: CCD camera (camera member)
E: Electronic parts (work)
H ... Mounting heads M, M1, M2 ... Alignment marks Om, Om ', Om1, Om2 ... Center Op, Op' ... Image origin P, P '... Image S ... Support table T ... Transport table [Delta] X, [Delta] X', [Delta] Y , ΔY '... deviation amount

Claims (3)

In a method for detecting the position of an alignment mark displayed on a work by imaging with a camera member,
The part where the alignment mark of the workpiece is displayed is imaged by the camera member, and the first detection of the center position of the alignment mark is performed.
The relative position between the camera member and the work is determined based on the detected value of the center position of the alignment mark detected first so that the center of the alignment mark of the work is located on the center line of the camera lens of the camera member. Make the first adjustment to
After the first adjustment, the camera member performs imaging of the portion where the alignment mark of the work is displayed again to detect the center position of the alignment mark,
A method for detecting the position of an alignment mark. The second imaging by the camera member after the first adjustment of the relative position of the camera member and the work, and the second adjustment of the relative position of the camera member and the work based on the detected value of the center position of the alignment mark by the second imaging. 2. The method according to claim 1, wherein the method is performed at least once. When detecting the positions of the respective alignment marks displayed on the two workpieces to be joined together, the portions of the two workpieces where the respective alignment marks are displayed are positioned at positions where the respective workpieces are joined. Adjusting the relative position between the camera member and the work based on the first image pickup by the camera member and the detected value of the center position of the alignment mark detected by the first image pickup; and the relative position between the camera member and the work 2. The alignment mark position detecting method according to claim 1, wherein the center position of the alignment mark is detected by re-imaging by the camera member after the adjustment.

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