JPH0824235B2 - How to determine the mounting position of electronic components in a mounting machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mounter for electronic components, and more particularly to a method for determining the mounting position of electronic components in a mounter that requires high accuracy in positioning.

[Conventional technology]

In the conventional method, a method has been adopted in which the center of gravity of the pattern is obtained from the marking pattern or the lead pattern on the substrate, and the center of gravity is used as the mounting position to issue a command to the mounting robot.

Further, as in the invention (see Japanese Patent Laid-Open No. 63-139679) related to the application of Japanese Patent Laid-Open No. 61-282024 by the same applicant as the present application (see Japanese Patent Laid-Open No. 63-139679), the light of the visual recognition camera is placed at the position on the center line of the hand. When the axes cannot be aligned, there is a deviation amount between the center line of the hand and the optical axis of the camera, that is, an offset amount, so that the offset amount must be corrected.

Furthermore, the same applicant sets a measurement line in a contact pattern or a lead pattern as described in the invention (see JP-A-62-86789) related to the application of JP-A-60-224852, Based on the brightness distribution on the measurement line, the center position and posture of the contact or the lead is obtained, and a correction method is proposed in which the lead of the component can be accurately mounted on the contact.

[Problems to be solved by the invention]

The above-mentioned related art does not consider the shape error of the pattern of the contacts on the board and the mounting parts, that is, the manufacturing error that occurs when the board and the parts are manufactured, or
High-accuracy mounting was not always performed due to an offset error when converting the mounting position captured by the visual recognition camera into the actual mounting position.

The object of the present invention enables high-precision mounting regardless of manufacturing errors that occur during the manufacture of substrates and parts, and does not require an offset between the actual mounting position and the mounting position captured by the visual recognition camera. Especially.

[Means for solving the problem]

The above-described object is to mount an electronic component having a plurality of leads on a plurality of sides in alignment with a contact provided on a printed circuit board in a mounter for an electronic component equipped with a visual recognition device. The column is read and displayed by the camera of the visual recognition device, and a plurality of measurement lines intersecting the pattern of the contact in the direction of the column are set on the pattern representing the contact and stored in the visual recognition device. A pattern that represents the lead by moving the electronic component held by a hand of the mounting machine to a mounting position of the board, and recognizing the lead on the same image of the contact and the visual recognition device. An overlapping image of patterns representing the contact points is two-dimensionally captured, and the position of the electronic component with respect to the mounting position of the substrate is determined based on the width dimension of the image along the plurality of measurement lines. It is achieved by mounting to correct the.

[Action]

When mounting the leads of the component on the contacts arranged in rows on the printed circuit board, first capture the contact image with the camera of the visual recognition device and display it. , A plurality of measurement lines are set on the row of the patterns representing the displayed contact points at positions intersecting the pattern in the row direction, and are temporarily stored in the visual recognition device.

Next, the parts held in the hand of the mounting machine are stopped at a height just before contact with the contacts so that the leads can be seen overlapping each other. Set the measurement line on the overlapped image, calculate the width dimension of the overlapped pattern from the brightness distribution of the measurement line, and compare it with the allowable dimension (threshold value) given in advance to satisfy the threshold value. By moving the hand to the right, it is possible to mount it in the correct position.

It is sufficient to set the above measurement line only for the first first substrate. This is because the second and subsequent substrates are manufactured with such an accuracy that they intersect the measurement line set on the first substrate.

The above operation is to be executed by being automatically instructed by the visual recognition device.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is an external view of the electronic component mounter used in the embodiment.

In the figure, reference numeral 1 shows a robot hand for holding electronic components and mounting them on a printed circuit board 2.

The hand 1 can be arbitrarily moved in any of the X and Y directions by the orthogonal robot 3 controlled by a program.

First, when the first first substrate 2 is loaded into a predetermined position and stopped, the orthogonal robot 3 moves according to a given command, and the contact pattern 6 is read by the camera 4 provided on the mounting head, In the recognition device, a specified number of measurement lines are set and stored above the contact row.

The hand 1 holds the component to be mounted on the substrate 2 from the component supply device 5. Then, the component 8 is held close to the contact pattern 6 of the printed circuit board 2 just before the contact.

FIG. 1 is an enlarged view of the mounting head 7 portion used in the embodiment.

The mounting head 7 is moved by the program of the robot 3 given in advance, and the component 8 gripped by the hand 1 is moved to the position of the designated contact pattern 6 of the printed circuit board 2.

The mounting head 7 includes the pattern 6 on the printed circuit board 2,
In order to recognize the lead pattern of the component 8 within the same field of view, the component 8 is lowered onto the contact pattern 6 of the substrate until just before the contact. Therefore, the hand 1 is provided with a mechanism that can move in the Z-axis direction. With this mechanism, the component 8 is held at a position just before mounting, and the camera 4 changes the contact pattern 6 and the lead pattern of the component 8. Both are imaged in an overlapping state, a measurement line that has been set and stored in advance is set on the image, the mounting position is corrected from the distribution of brightness on the measuring line, and the mounting position is determined.

FIG. 3 shows a contact pattern 9 on the printed circuit board 2,
The image where the lead pattern 10 of the component 8 overlaps
It is the figure which showed the state recognized by the visual recognition device.

In this third image, as shown in the figure, the measurement lines that are preset and stored, that is, the upper measurement lines LU _{1 to} LU ₄ ,
The lower measurement lines LD _{1 to} LD ₄ , the right measurement lines LR _{1 to} LR ₄ , and the left measurement lines LL _{1 to} LL ₄ are set, respectively.

Then, the boundary position coordinates of the pattern are obtained from the brightness distribution of the image pattern in the state where the contact pattern 9 on each of these measurement lines and the lead pattern 10 of the component 8 overlap, and the image pattern in the overlapping state is obtained. Measure the width dimension of. The details of how to obtain the boundary position coordinates are described in the specification of JP-A-60-224852.

The measured results are as shown in Tables 1 to 4 below.

First, the presence or absence of a deviation in the rotational direction is determined by the number of measured patterns. If there is no deviation in the direction of rotation,
Number of lines in measuring line LU ₁ = Number of lines in measuring line LU ₂ = Number of lines in measuring LU ₃ = Number of lines in measuring line LU ₄ or Number of lines in measuring line LR ₁ =
Number of measurement lines LR ₂ = ... = Number of measurement lines LL ₃ = Measurement line LL
The relationship of the number at ₄ is established.

Looking at the measurement results in FIG. 3, the number of lines in the upward direction (3,
4, 6, 6) and the number of lines in the downward direction (3, 3, 4, 4) does not hold the above-mentioned equal relationship, so it can be determined that there is a deviation in the rotational direction.

Next, in order to obtain the correction amount of the displacement in the rotation direction, the average value in the width direction on the measurement line LU ₁ , that is, the average value = (DU ₁₁ + DU ₁₂ + DU ₁₃ ) / 3, is used. Calculate the average value of the pattern width on the measurement line LU ₄ from LU ₁ .

FIG. 4 is a graph showing the calculation result of the average value of the pattern widths from the measurement line LU ₁ to the measurement line LU ₄ .

In FIG. 4, the straight line SL represents the measurement result by a linear expression, and the correction of the rotation direction is performed by bringing the straight line SL close to the straight line TL based on the theoretical formula when there is no deviation in the rotation direction. is there. That is, the angle θ ₁ is the correction amount.

Similarly, for each measurement line, LD ₁ to LD ₄ , LR ₁ to LR ₄ , LL ₁ to LL ₄ , when the average value of the width dimension on each measurement line is obtained and plotted on the graph, straight line SL and straight line TL are The inclination of the same angle θ ₁ is shown.

The broken line in FIG. 4 shows the case of the measurement lines LL ₁ to LL ₄ for comparison, and therefore, the angle θ ₁ to be corrected can be obtained only by calculating one of the sides. .

Therefore, in order to improve the accuracy, this rotation direction correction is performed a plurality of times as shown in the flowchart of FIG.

Next, FIG. 5 shows an image pickup result obtained by correcting the rotation direction from the state of FIG.

 Therefore, this time, the correction amount in the XY direction is calculated.

As described above, the dimension of the pattern width is calculated using each of the measurement lines LR _{1 to} LR ₄ and LL _{1 to} LL ₄ . Then, the total average value of the calculation results, that is, the total average value = (DR ₁₁ + DR ₁₂ + ... + DL ₄₂ + DL ₄₃ ) / (8 ×
3) is corrected by being corrected so as to be approximated to a permissible range set in advance for each pattern, that is, the threshold value T.
The direction can be corrected.

Therefore, (DR ₁₁ + DR ₁₂ + ... + DL ₄₂ + DL ₄₃ ) / (8 × 3) −T is the correction amount in the Y direction.

Then, this correction is also performed a plurality of times, and if the correction is not performed even if the correction is performed the specified number of times or more, it is considered as a defective part.

The correction amount in the X direction can be calculated in the same manner.

A flowchart of the algorithm described above is as shown in FIG.

As described above, according to this embodiment, by matching the patterns with each other, there is no relation to the manufacturing error of the board or the component, and the actual mounting position and the mounting position detected by the visual recognition camera are not affected. There is no need to have the offset of, and the effect that high-precision mounting can be obtained is obtained.

〔The invention's effect〕

According to the present invention, irrespective of the variation in the shape accuracy of the board and parts, it is not necessary to have an offset between the actual mounting position and the mounting position captured by the visual recognition camera,
The effect is that it can be mounted with high precision.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged perspective view of a mounting head section showing an embodiment of the present invention, and FIG. 2 is a perspective view showing an overall configuration of an electronic component mounting machine showing an embodiment of the present invention. FIG. 3 is an image pickup diagram in which an overlapping pattern is recognized by a visual recognition device, FIG. 4 is a diagram showing an example of a measurement result, FIG. 5 is an image pickup diagram in which an overlapping pattern is recognized by a visual recognition device, and FIG. The figure is a flow chart showing an example of the processing according to the present invention. 1 ... Mounting hand, 2 ... Printed circuit board, 3 ... Orthogonal robot, 4 ... Visual recognition camera, 5 ... Component supply device, 6 ... Board pattern, 7 ... Mounting head, 8 ... Electronic component , 9: Patterns on the board taken by the visual recognition camera, 10: Lead patterns of parts taken by the visual recognition camera.

Claims (1)

[Claims] 1. A mounter for an electronic component, comprising a visual recognition device for mounting an electronic component having a plurality of leads on a plurality of sides in accordance with a contact provided on a printed circuit board, wherein the contacts are aligned. A row of rows is read and displayed by the camera of the visual recognition device, and a plurality of measurement lines intersecting the pattern of the contact points in the direction of the row are set on the pattern representing the contact points and stored in the visual recognition apparatus. Then, after moving the electronic component held by the hand of the mounting machine to the mounting position of the board, the lead is recognized on the same image of the contact and the visual recognition device, and a pattern representing the lead And two-dimensionally capturing the overlapping images of the patterns representing the contact points, and based on the width dimension of the images along the plurality of measurement lines, the electronic component of the electronic component with respect to the mounting position of the substrate Mounting position determining method of the electronic component in the mounting apparatus, characterized in that mounted to correct the location.