JP2000310519A - Method and device for measuring position of package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an added data for measurement of position even if a plurality of picture data of reference marks on a package is insufficient as one data by computing a deviation between a calculated position of a reference mark and that of a reference mark when the package is placed on the reference mark. SOLUTION: First, an XY stage mounted with a camera is driven to move to either of reference marks 3 on a package 1, and a picture data is picked up by the camera. In the same manner, the picture data of all reference marks on the package 1 are picked up sequentially. A distance of movement of the camera is set to a distance between the reference marks. The dense and light information of inputted four picture data is added as one dense and light data. Then the dense and light data is converted into a binarized bright and dark data by using a preset threshold 4. Finally, a quantity of deviation between a center of visual field and the position of the reference mark is obtained mathematically by using the upper data than the threshold 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a package position measuring device and a position measuring method using image data obtained by imaging.

[0002]

2. Description of the Related Art When measuring the position of various packages such as a semiconductor package, a reference mark for position measurement is attached to the package in advance, and the reference mark is imaged by a camera to perform data processing. Then, the shift amount of the package position is calculated, and the XY stage holding the package is driven to correct the position.

In this case, when taking an image with a camera, the distance between the reference marks is large with respect to the field of view of the camera.
Since it is not possible to image all the reference marks at one time, it is performed a plurality of times. The movement of the camera position and the camera field of view is performed by an XY stage on which a camera is mounted.

To calculate the amount of displacement of the package, a reference mark is identified from the input image, the amount of displacement from the center of the camera's field of view is calculated, and added to the amount of movement of the camera to calculate the coordinates from the reference point. . In this process, the shift of the center of the package is calculated from the coordinates of two or three points by moving the camera view.

[0005] The image data taken in here is gray-scale data, and in order to make the reference mark on the package easy to understand, a difference in brightness is provided by using illumination. The light and dark data are distinguished into two types, bright and dark, based on the set threshold value, and the position of the reference mark 4 is measured as shown in FIG. 3B.

[0006]

Here, a threshold value is used to distinguish between light and dark.
The lighting condition changes under the influence of the surface condition of the package, etc.
In some cases, the difference in shading is small. If the difference in shade is small,
As shown in FIG. 3C, a slight difference in the setting of the threshold value changes the determination between light and dark, and changes the measurement result, resulting in a problem that the measurement is not performed correctly.

As a method of increasing the density difference, there is a method of enlarging the density data a plurality of times. However, the reference mark shape is changed due to the influence of the illumination or the surface condition of the object to be measured. In this case, as shown in FIG. 4, there arises a problem that the measurement is not performed correctly.

Therefore, without being affected by such
There has been a demand for a position measurement method capable of performing accurate measurement.

[0009]

According to the present invention, there is provided a package position measuring apparatus comprising: a package mounting table for holding a package having a plurality of reference marks provided at predetermined positions; an image pickup apparatus held on the package mounting table; An imaging device moving mechanism that moves the imaging device in a predetermined direction by a predetermined distance; an image data storage unit that stores image data captured by the imaging device; and a plurality of images stored in the image data storage unit An image data addition unit that adds data, a reference mark position calculation operation unit that calculates a reference mark position using a predetermined threshold from the added image data,
A package shift amount calculation unit that calculates a shift amount between the reference mark position calculated by the reference mark position calculation operation unit and the reference mark position when the package is positioned at the reference position. is there.

FIG. 1 shows a block diagram of an embodiment of the package position measuring device according to the present invention.

The package position measuring device of the present invention has an image input position setting unit, and the image pickup device moving mechanism sequentially moves the image pickup device to the coordinates set by the image input position setting unit, and sequentially picks up the image. And input image data.

Further, in the package measuring method according to the present invention, a plurality of reference marks provided on the package are respectively imaged by an image pickup device, and image data of the reference marks are input together with position data, and the image data is stored. Addition image data is created by adding the image data of the plurality of reference marks, a reference mark position is obtained by using a predetermined threshold value for the addition image data, and a package is provided at the mark position and the reference position. The position of the package is measured by calculating the amount of deviation from the position of the reference mark when is located.

In the present invention, it is preferable that the direction of movement of the camera and the direction of the package be well aligned in advance.

In the present invention, as the shape of the reference mark on the package, a circular mark, a polygonal mark, a cross mark, or the like can be appropriately selected and used. The number of fiducial marks may be plural, and as the number increases, the number of imaging inputs must be increased and the addition process must be performed. However, the more the number increases, the more accurate position measurement becomes possible.

According to the present invention, even when image data of a plurality of reference marks on a package is not sufficient as one data, it can be used for position measurement by using the added data as the added data. Therefore, when there is a partial defect in the input image data or the reference mark, the influence of the defective reference mark is removed and the reliability of the package position measurement is maintained without the need for complicated shape recognition processing. be able to.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be specifically described based on examples.

(Embodiment 1) In FIG. 2, an XY stage on which a camera is mounted is first driven to move to any one of the reference marks 3 on the package 1, and image data is taken in by the camera. Similarly, the operation of driving the XY stage on which the camera is mounted, moving the camera to the position of another reference mark, and taking in the image data is sequentially performed, and the image data of all the reference marks on the package 1 is taken in. Here, the moving distance of each camera is set to the distance between the reference marks.

The grayscale information of the four input images is added to form one grayscale data. Then, as shown in FIG. 5B, the grayscale data is converted into binarized light / dark data by the set threshold value 4.

Finally, using the data above the threshold value 4, the shift amount between the center of the visual field and the reference mark position is calculated by a general mathematical method.

When there is no shift in the package, the reference mark 3 is located at the center of the field of view of the camera, and when the image data is added, all the reference marks are at the center of the field of view. It has become.

On the other hand, when the package is displaced in the horizontal direction, that is, in the X direction, the reference marks move in the horizontal direction, and as shown in FIG.
With one reference mark 3, the image is shifted in the horizontal direction by an amount shifted from the center of the visual field. Also, if the package is in the vertical direction,
The same applies to the case where the image is displaced in the direction, and the composite image is an image that is displaced in the vertical direction by an amount corresponding to the deviation from the center of the visual field with one reference mark 3. In this case, by using the composite image as shown in FIG. 5B, the difference in the gray level of each image data is increased by adding the image data, and the reliability of the image data is improved.

Therefore, even if the grayscale data slightly changes with respect to the set threshold value, stable binarization can be performed, and the reliability of measurement is improved.

(Embodiment 2) If one of the reference marks on the semiconductor package has a shape defect as shown in FIG. 6, for example, four image data are added and the same as the other three reference marks. Since it is considered that the defective shape portion is not usually present, as shown in FIG. 6, the added value of the shading due to the defective shape portion is smaller than the added value of the shading due to the reference mark itself. And has no effect on the package position detection. That is, as shown in FIG. 6B, the data of the defective portion is automatically deleted at the stage of binarization, and only the normal reference mark is measured, so that no measurement error occurs.

Even when a plurality of reference marks on the package have a shape defect, if the shape defects are different from each other, no measurement error similarly occurs.

Next, as shown in FIG. 7, even if one of the reference marks is defective, if the position of the other reference mark is correct, the defective reference mark can be automatically deleted. it can.

Also, as shown in FIG. 8, even when the size of the reference mark is different, the center position of the reference mark does not change. Can be.

[0027]

According to the present invention, by adding the image data of a plurality of reference marks on a package such as a semiconductor package, the grayscale difference is amplified, and even small grayscale data can be accurately measured. it can. Further, when there is some defect in the reference mark, the influence of the defective reference mark can be removed without requiring complicated shape recognition processing, and the reliability of the package position measurement can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a package position measuring device according to the present invention.

FIG. 2 is an arrow showing the order in which a reference mark portion of a package is imaged and an image is input according to the embodiment of the present invention.

3A and 3B are image data obtained by imaging one reference mark in a conventional package position measurement, wherein FIG. 3A is two-dimensional image data of one reference mark, and FIG. And (c) shows the case where the shading data crosses the reference mark and the shading difference is small.

4A and 4B are image data obtained by imaging one reference mark in the conventional package position measurement, and FIG. 4A shows two-dimensional image data of the reference mark, and when the reference mark image data is deformed, b) shows the case where the detection position is shifted due to deformation in the grayscale data crossing the reference mark.

5A and 5B are image data obtained by capturing four reference marks in one embodiment of the package position measurement according to the present invention, wherein FIG. 5A is two-dimensional image data obtained by adding four reference marks, and FIG. Indicates light and shade data of only four reference marks.

6A and 6B are image data obtained by capturing four reference marks in one embodiment of the package position measurement according to the present invention, wherein FIG. 6A is two-dimensional image data obtained by adding four reference marks, and FIG. Indicates shading data, in which case one of the reference marks has a defective shape.

7A and 7B are image data obtained by capturing four reference marks in one embodiment of the package position measurement according to the present invention, wherein FIG. 7A is two-dimensional image data obtained by adding four reference marks, and FIG. Indicates the density data, in which a position defect is recognized in one of the reference marks.

8A and 8B are image data obtained by capturing four reference marks in one embodiment of the package position measurement system according to the present invention, wherein FIG. 8A shows two-dimensional image data obtained by adding four reference marks, and FIG. ) Is the shading data and shows the case where a dimensional defect is recognized in the reference mark.

[Explanation of symbols]

1 ... Package, 2 ... Camera view, 3 ...
..Position measurement reference mark, 4 ... Threshold, 5 ...
··· Reference mark for defective position, 6: Reference mark for defective shape, 7: Reference mark for defective size.

Claims (3)

[Claims] 1. A package mounting table for holding a package having a plurality of fiducial marks provided at predetermined positions, an imaging device held on the package mounting table, and moving the imaging device by a predetermined distance in a predetermined direction. An image capturing device moving mechanism, an image data storing unit that stores image data captured by the image capturing device, an image data adding unit that adds a plurality of image data stored in the image data storing unit, A reference mark position calculation operation unit that calculates a reference mark position using a predetermined threshold from image data,
A package shift amount calculation unit that calculates a shift amount between the reference mark position calculated by the reference mark position calculation operation unit and the reference mark position when the package is located at the reference position. Measuring device. 2. The package position measuring device has an image input position setting unit, and the image pickup device moving mechanism sequentially moves the image pickup device to coordinates set by the image input position setting unit, and sequentially picks up images. 2. The package position measuring device according to claim 1, wherein the image data is input by inputting the image data. 3. A plurality of fiducial marks provided on a package are respectively imaged by an image pickup device, and image data of the fiducial marks are input together with position data to store the image data. Addition image data is created by adding the image data, a reference mark position is obtained by using a predetermined threshold value for the addition image data, and a reference mark when the package is located at the mark position and the reference position. A package position measuring method, wherein a package position is measured by calculating an amount of deviation from the position.