JPH05332724A - Measuring method of printed board standard position - Google Patents

Abstract

PURPOSE:To precisely measure a standard position in any case by making a black-and-white pattern into a binary, and setting both vertical and horizontal windows for measuring a cross mark. CONSTITUTION:The smallest value in a horizontal image histogram 7 is searched, it is judged whether the histogram value near the smallest value satisfies the measuring condition for the detection of a cross mark width or not, and a vertical cross mark measuring window 9 including a width of K2 is formed. Similarly, the smallest value in a vertical image histogram 8 is searched, and a horizontal cross mark measuring window 10 including a width of L1 is formed. Finally, after measuring the edges of a cross mark 3 from the histogram values of all picture elements in the windows 9, 10, the widths of the vertical and horizontal edges are determined with the intersection of the central lines 4, 5, or the central point of the cross mark 3 as a standard position 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual device such as lighting and image pickup, an image processing device such as a frame memory, and the like, regardless of human hands.
Use a robot or the like to move the I
The present invention relates to a method of measuring a reference position when positioning and mounting components such as C and LSI and check pins.

Due to the miniaturization and high functionality of printed circuit boards,
There is a need for a technology for positioning at high speed and with high precision in order to cope with the trend toward higher density mounting of components on printed circuit boards and the resulting miniaturization of mounted components.

[0003]

2. Description of the Related Art FIGS. 2 and 3 are explanatory views of a conventional example. In the figure, 1 is a printed circuit board, 2 is a window, 3 is a cross mark, 7 is a horizontal image histogram, 8 is a vertical image histogram, 11 is a component such as IC and LSI, 12 is noise, 13 is dust, Scratches, etc., 14 are fading, missing, etc.

As shown in FIG. 2A, the printed circuit board 1
At least one reference mark such as the cross mark 3 is used as a means for obtaining the reference position 6 in order to accurately position and mount the component 11 such as IC or LSI and the check pin at the mounting position above. It is provided.

The procedure for measuring the reference position 6 from the conventional cross mark 3 will be described below. First, after capturing the cross mark 3 with a camera, the image data is binarized and loaded into the window 2, which is a frame memory, and as shown in FIG.
An image histogram 7 in the horizontal direction and an image histogram 8 in the vertical direction are obtained. In this case, noise such as dust and scratches 1
2 is also taken in at the same time.

Next, as shown in FIG. 3 (c), the maximum points (b in the figure
1, b2). However, the value of the image histogram of this maximum point is a value (B that is set in advance as a parameter so as to satisfy the design condition of the cross mark 3).
It must be within the range of (L, BH).

Further, as shown in FIG. 3 (d), the minimum points (w1 and w2 in the figure) are searched inward from the two maximum points b1 and b2 of the horizontal image histogram 7.
However, the value of the image histogram of this minimum point is the value (WL,
It must be within the range of (WH).

The average value Ave b is the average value of the image histogram values of b1 and b2. Although not shown, the maximum point and the minimum point are similarly obtained in the vertical image histogram 8.

After the edge of the cross mark is detected as described above, the center of gravity of the pixels within the range surrounded by the edge of the cross mark 3 is obtained using the image histograms 7 and 8 and is set as the reference position 6. ..

[0010]

According to the conventional reference position measuring method, the edge of the cross mark 3 is detected by focusing only on the increase amount and the decrease amount of the black level in the histogram of the mark image. As shown in (e), when there are 13 images such as dust and scratches in the vicinity of the cross mark 3, there is a possibility that they are mistakenly recognized as the cross mark 3 or a part thereof. ..

Further, if the image of the cross mark 3 has a blur or a missing portion 14, it may be affected by the calculation of the center of gravity of the cross mark 3 and an error may occur at the substrate position 6.
In view of the above points, the present invention reduces the substrate position measurement error caused by scratches or dust in the vicinity of the reference mark when a reference mark such as the cross mark is used, or image blurring, and accurately reads the cross mark. Develop a method,
It is intended to improve the mounting accuracy of semiconductor components such as IC and LSI.

[0012]

FIG. 1 illustrates the principle of the present invention. In the figure, 3 is a cross mark, 4 is a vertical centerline, 5 is a horizontal centerline, 6 is a reference position, 7 is a horizontal image histogram, 8 is a vertical image histogram, and 9 is a vertical cross. Mark measurement window, 10 is a horizontal cross measurement window.

According to the present invention, the cross mark 3 which is a reference mark is used.
After setting the vertical cross mark measurement window 9 and the horizontal cross mark measurement window from the nearby images,
Using the image histogram in the window, the edge of the cross mark 3 is detected in the same way as in the conventional method, and the intersection of the vertical center line 4 and the horizontal center line 5 of the cross mark is found. The reference position 6 is the center position of the mark 3.

That is, as shown in FIG. 1C, the object of the present invention is to process an image of a cross mark 3 which is a reference mark in the window 2 on the printed circuit board 1 on the printed circuit board 1 taken by the camera by the image processing device. Then, the reference position 6 on the printed circuit board
In the method of measuring, in the window 2 for measuring the cross mark 3 which is the camera field of view on the printed circuit board 1,
Binarization into a black and white pattern, the vertical centerline 4 and the horizontal centerline 5 of the cross mark 3 are obtained, and the vertical centerline 4 is obtained.
In the method of determining the vertical center line 4 and the horizontal center line 5 of the cross mark 3 by setting the intersection of the horizontal center line 5 and the horizontal center line 5 as the reference position 6 of the printed circuit board 1, As shown in (b) and (c), from the image histogram 7 in the horizontal direction and the image histogram 8 in the vertical direction in the window 1, the vertical direction with respect to the area that fits within the preset width range of the cross mark 3 is displayed. After setting the horizontal cross mark measurement window 9 and the horizontal cross mark measurement window 10, the image histograms in the vertical cross mark measurement window 9 and the horizontal cross mark measurement window 10 are displayed. It is achieved by detecting the edges of the cross mark 3 and determining the vertical center line 4 and the horizontal center line 5 of the cross mark 3 using.

[0015]

According to the present invention, since the cross mark can be distinguished from the image other than the mark body near the cross mark, and the reference position can be measured without being affected by the blur or loss of the mark image, the vicinity of the mark can be measured. Even a printed circuit board that is subject to adverse conditions such as dust adhesion and scratches can be measured, and the reference position can be measured without fine adjustment of the illumination system.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the principle of the present invention and an explanatory diagram for one embodiment. An embodiment of the present invention will be described with reference to FIGS. 1 to 3 used in the above description.

FIG. 3E shows an image in the vicinity of the cross mark 3 serving as a reference, and includes 13 images such as dust and scratches. Also, the image itself of the cross mark 3 is faint and missing 14 or the like.

FIG. 1A shows the image histogram 7 in the horizontal direction of the image of FIG. 3E taken every other line. A local minimum value in this histogram is searched, and it is determined whether or not the histogram value near the local minimum value satisfies the determination condition for detecting the cross mark width, and the window position for cross mark measurement is determined.

A1 is the minimum value found first, k1 is the width of the white level at the cross mark width determination position at that time,
The width of the cross mark 3 set in advance is exceeded.
Next, when the minimum value of A2 is taken, its width K2 substantially matches the set value of the width of the cross mark 3. Therefore,
As shown in (c), a vertical cross mark measurement window including a width of k2 is created.

Further, FIG. 1 (b) shows the image histogram 8 in the vertical direction of the image of FIG. 3 (e) taken every other line. A local minimum value in this histogram is searched, and it is determined whether or not the histogram value near the local minimum value satisfies the determination condition for detecting the cross mark width, and the window position for cross mark measurement is determined.

B1 is the minimum value found first, L1 is the width of the white level at the cross mark width determination position at that time,
It is within the preset width range of the cross mark 3. Therefore, as shown in FIG. 1C, a horizontal cross mark measurement window 10 including the width of L1 is created.

Finally, as shown in FIG. 1C, after measuring the edge of the cross mark from the histogram values of all the pixels in the two measurement windows 9 and 10 previously defined, the widths of the vertical and horizontal edges are determined. A point where the center lines 4 and 5 intersect, that is, a cross mark 3
The center point of is determined as the reference position 6.

According to this method, the deviation of the reference position 6 due to the erroneous recognition of the cross mark 3 due to dust or scratches and the measurement error of the reference position 6 due to the blurring of the image are reduced.

Further, the cross mark measuring windows 9 and 10
Although the number of steps required for setting is greater than in the past, the histogram measurement at that time is performed every other line, so the amount of measurement time extension is small.

[0025]

As described above, according to the present invention,
Since the reference position can be accurately measured by the cross mark itself and the noise image around the cross mark such as dust and scratches, the reference position can be accurately measured, so that semiconductor parts such as IC and LSI can be mounted with high accuracy. ..

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is an explanatory diagram of a conventional example (No. 1)

FIG. 3 is an explanatory diagram of a conventional example (No. 2)

[Explanation of symbols]

 1 Printed circuit board 2 Window 3 Cross mark 4 Vertical center line 5 Horizontal center line 6 Reference position 7 Horizontal image histogram 8 Vertical image histogram 9 Vertical cross mark measurement window 10 Horizontal cross mark measurement window 11 Parts such as IC and LSI 12 Noise 13 Dust, scratches, etc. 14 Blurring, missing, etc.

Claims (2)

[Claims] 1. An image processing apparatus processes an image of a cross mark (3) which is a reference mark in a window (2) on a printed circuit board (1) captured by a camera, and a reference position ( In the method of measuring 4), the printed circuit board (1)
The cross mark (3) which is the field of view of the upper camera is binarized into a black and white pattern in the measurement window (2), and the vertical center line (4) and the horizontal center line of the cross mark (3) are binarized. (5) is obtained, and the intersection of the vertical centerline (4) and the horizontal centerline (5) is set as the reference position (6) of the printed circuit board (1). Measuring method 2. The vertical center line of the cross mark (3)
(4) and the centerline in the horizontal direction (5), the cross-shaped image that was previously set from the horizontal image histogram (7) in the window (1) and the vertical image histogram (8). After setting the vertical cross mark measurement window (9) and the horizontal cross mark measurement window (10) for the area conforming to the width range of the mark (3), the vertical cross mark measurement window The edge of the cross mark (3) is detected using the image histogram in the window (9) and the cross mark measurement window (10) in the horizontal direction, and the center of the cross mark (3) in the vertical direction is detected. 2. The printed circuit board reference position measuring method according to claim 1, wherein the line (4) and the lateral center line (5) are determined.