JPH08236997A - Method of correcting mounting position of mounting device - Google Patents

Abstract

PURPOSE: To obtain a proper correction position even if a substrate is distorted by operating a correction position of a part mounting place based on relative position relation of the theoretical position of a part mounting position to the theoretical position of each of four or more measurement points and a measured position of the measurement points. CONSTITUTION: A printed board 3 is provided with a fiducial mark 40 at four or more measurement points in advance. The coordinates of a theoretical position of each measurement point provided with the fiducial mark 40 and the coordinates of a theoretical point of a part mounting place are stored in a memory part 34 of a control device 30 in advance. Then, each fiducial mark 40 is imaged one by one by a substrate recognition camera 27 and each position is measured. After the measured position of the measurement points is obtained, a corrected position of a part mounting place is operated based on a coordinate conversion parameter obtained from relative position relation of the theoretical position of a part mounting place to the theoretical position of each measurement point and the measured position of each measurement point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting position correcting method for correcting a mounting position in a mounting machine for mounting a component on a printed circuit board in accordance with a displacement, deformation or the like of the printed circuit board.

[0002]

2. Description of the Related Art Conventionally, a component mounting head having a nozzle member transfers a component such as an IC from a component supply section onto a positioned printed circuit board and mounts it at a predetermined position on the printed circuit board. Such a mounting machine is generally known.

In such a mounting machine, the theoretical position of the component mounting location on the printed circuit board is stored in advance. However, if there is a displacement of the printed circuit board or the like, it is possible to simply mount the component at the theoretical position. Error occurs. Therefore, it has been conventionally performed to check the positional deviation of the printed circuit board and correct the component mounting position accordingly.

In the conventional mounting position correcting method of this type, generally, fiducial marks are attached to two points on a printed circuit board, and at the time of mounting, the above-mentioned fiducial is detected by a camera provided in a component mounting head. The charmark is detected and the position thereof is measured, whereby the displacement of the printed circuit board or the like is checked and the coordinate conversion is performed accordingly.

[0005]

According to the conventional method as described above, the X and Y of two fiducial marks are formed.
By measuring the coordinates, it is possible to check the positional deviation in the X and Y directions, the inclination of the board, and the expansion of the board due to thermal expansion, and it is possible to correct the deviation of the mounting position due to these factors. Is.

However, if the material of the substrate is relatively easily deformed, in addition to the above-mentioned displacement, inclination, and elongation, the distortion and distortion of the two-dimensional plane of the substrate are also major factors that cause the displacement of the mounting position. However, when such a distortion of the substrate occurs, the conventional method cannot perform the corresponding correction, and there is a problem that the accuracy of the component mounting position decreases.

In view of the above circumstances, the present invention provides a mounting machine capable of correcting the component mounting position in accordance with the distortion of the printed circuit board and greatly improving the accuracy. An object is to provide a mounting position correction method.

[0008]

The invention according to claim 1 is
In a mounter that picks up a component from a component supply unit by a component mounting head and mounts it on a component mounting location on a printed circuit board, four or more measured points are set on the printed circuit board and the theory of each measured point is set. The position and the theoretical position of the component mounting location are stored in advance, the measuring points provided on the component mounting head are used to detect the measured points, and the positions are measured. The corrected position of the component mounting location is calculated based on the parameter obtained from the relative positional relationship of the theoretical position of the component mounting location with respect to the position and the actually measured position of each measured point measured by the detecting means. It was done like this.

According to a second aspect of the present invention, there is provided a method of correcting a component mounting position according to the first aspect, wherein the printed circuit board 4
The fiducial marks attached to the points to be measured or more are imaged by the image pickup means provided in the component mounting head to measure the points to be measured.

[0010]

According to the method of claim 1, there are four or more measured points for checking the displacement and deformation of the board, and the relative position of the component mounting position to the theoretical position of each measured point. By calculating the correction position of the component mounting position based on the actual positional relationship and the measured position of the measured point, even if the board is distorted due to the distortion of the two-dimensional plane of the printed board, The correction position of the mounting location is properly obtained.

According to the method of the second aspect, the measurement of each of the measured points is easily performed.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

1 and 2 show the structure of a mounting machine to which the method of the present invention is applied. As shown in the figure, a conveyor 2 for conveying a printed circuit board is arranged on a base 1 of the mounting machine, and the printed circuit board 3 is conveyed on the conveyor 2 and stopped at a predetermined mounting work position. It has become. A component supply unit 4 is arranged on the side of the conveyor 2. The component supply unit 4 includes a component supply feeder, for example, a multi-row tape feeder 4a.

A head unit (component mounting head) 5 for mounting components is installed above the base 1. The head unit 5 is movable across the component supply unit 4 and the component mounting unit on which the printed circuit board 3 is located. In this embodiment, the head unit 5 is in the X-axis direction (direction of the conveyor 2) and the Y-axis direction (X-axis on a horizontal plane). It is possible to move in the direction orthogonal to.

That is, a fixed rail 7 in the Y-axis direction and a ball screw shaft 8 which is rotationally driven by a Y-axis servomotor 9 are arranged on the base 1, and the head unit is mounted on the fixed rail 7. A support member 11 is arranged, and a nut portion 12 provided on the support member 11 is screwed onto the ball screw shaft 8. In addition, the support member 11 has an X
An axial guide member 13 and a ball screw shaft 14 driven by an X-axis servomotor 15 are arranged, and the head unit 5 is movably held by the guide member 13.
A nut portion (not shown) provided on the head unit 5 is screwed onto the ball screw shaft 14. And
By the operation of the Y-axis servomotor 9, the supporting member 11 is moved to Y
While moving in the axial direction, the head unit 5 moves in the X-axis direction with respect to the support member 11 by the operation of the X-axis servomotor 15.

Further, the Y-axis servomotor 9 and the X-axis servomotor 15 are provided with position detecting devices 10 and 16 each composed of a rotary encoder, by which the moving position of the head unit 5 is detected. It is like this.

The head unit 5 is provided with one to a plurality of nozzle members for attracting components, and in the illustrated example, two nozzle members are provided.
Book nozzle members 21 and 22 are provided. Both of the nozzle members 21 and 22 are movable in the Z-axis direction (vertical direction) and rotatable about the R-axis (nozzle central axis) with respect to the frame of the head unit 5, and each of them is Z-shaped.
Axis servo motors 17, 18 and R axis servo motors 19,
20 (shown in FIG. 3). The servo motors 17 to 19 are respectively provided with position detecting means 23 to 25 (shown in FIG. 3) which are composed of encoders, by which the nozzle members 2 are provided.
The operation position detection of No. 1 is performed. Also,
Each of the nozzle members 21, 22 is connected to a negative pressure supply means (not shown) via a valve or the like, and a negative pressure for sucking components is supplied to the nozzle members 21, 22 when necessary.

Further, a board recognition camera 27 is attached to the head unit 5 as a detection means for detecting a measured point on the printed board. The board recognition camera 27 takes an image of the fiducial mark provided on the surface of the printed board 3.

Further, the base 1 is provided with a component recognition camera 29 for recognizing the suction state of the components sucked by the head unit 5. The component recognition camera 29 is arranged on the side of the component supply unit 4, and after the component supply unit 4 picks up a component, the head unit 5 is moved to a predetermined position above the component recognition camera 29. As a result, the suction component is imaged.

Next, the control system of the mounting machine will be described with reference to the block diagram of FIG.

A control device 30 as shown in FIG. 3 is mounted on the mounting machine, and the nozzle members 21 and 21 of the Y-axis and X-axis servomotors 9 and 15 and the head unit 5 are mounted.
The Z-axis servomotors 17 and 18, the R-axis servomotors 19 and 20, and the position detection means 10, 16 and 23 to 26 for the respective servomotors are all provided in the controller 30.
Is electrically connected to and is controlled by the control device 30. Specifically, the main computing unit 32 that controls the operation of the mounting machine in a centralized manner, the storage unit 34 that stores information about parts and the like, and is controlled by the main computing unit 32 based on the information stored in the storage unit 34. Axis control unit 31
Are provided in the control device 30, and the servomotors and the like are connected to the axis control unit 31.

The axis control section 31 and the main calculation section 32 perform control for performing a predetermined mounting operation at the time of mounting, and
When obtaining the correction position of the component mounting location as described below,
The head unit 5 is moved so as to arrange the board recognition camera 27 at a position corresponding to each fiducial mark on the printed board 3.

An image processing unit 33 is connected to the main computing unit 32, and the board recognition camera 27 and the component recognition camera 29 are connected to the image processing unit 33. Then, the board recognition camera 27 and the component recognition camera 2
By performing predetermined image processing on the image data taken in by 9 and outputting the image data to the main calculation unit 32, the main calculation unit 32 can recognize the fiducial mark of the printed circuit board 3 and the suction component. It is supposed to be done.

An embodiment of the mounting position correcting method in the mounting machine as described above will be described with reference to FIGS.

On the printed circuit board 3 which is carried into the predetermined mounting work position of the mounting machine, the fiducial marks 40 are preliminarily attached to four or more measured points. For example, as shown in FIG. When the substrate 3 has a rectangular shape, the fiducial marks 40 are provided at four points which are predetermined positions near the four corners. Further, printed wiring is provided on the printed circuit board 3, and components are mounted at a predetermined number of places according to the printed wiring and the like. The mounting location of this component is specified at the design stage.

In the method of this embodiment, the coordinates of the theoretical position of each measured point marked with the fiducial mark 40 and the coordinates of the theoretical position of the component mounting location are stored in advance in the control device 30. It is stored in the unit 34. FIG. 5 shows the coordinates of the theoretical position of each of the above-mentioned measured points and component mounting points, and points A (AX, AY) and point B (BX, B
Y), point C (CX, CY) and point D (DX, DY) are coordinates of theoretical positions of the above four fiducial marks (measured points), and point M (MX, MY) is one component mounting The coordinates of the theoretical position of the place.

After storing the coordinates of the theoretical position of each measured point and the component mounting position in this way, when mounting the component on the printed circuit board 3, first, the substrate recognition camera 27 provided in the head unit 5 is used. Above points A, B, C, D
The X-axis servomotor 15 and the Y-axis servomotor 9 are controlled so as to sequentially move to the positions corresponding to, and each of the fiducial marks 4 is moved by the board recognition camera 27.
0 is sequentially imaged and each position is measured. Thereby, the coordinates of the actually measured position of each measured point are obtained. Point a (ax, ay), point b (bx, by), point c (c shown in FIG. 6
x, cy) and the point d (dx, dy) are the coordinates of the actually measured positions of the above four fiducial marks 40 (points to be measured).

Positional deviation, inclination, extension of the printed circuit board 3,
When there is a distortion or the like, a square ABCD connecting the points A, B, C and D which are the theoretical positions of the measured point and the points a, b, c and d which are the measured positions of the measured point are connected. Quadrangle abc
The position on the coordinate, the size, the shape, and the like are different from d.

After the measured position of the measured point is obtained, the relative positional relationship of the theoretical position of the component mounting point (point M) with respect to the theoretical position of each measured point (points A, B, C, D). The correction position of the component mounting position is calculated based on the coordinate conversion parameter obtained from the above and the measured position (points a, b, c, d) of each of the measured points. For example, the correction position is calculated by the method shown in FIGS. 7A and 7B.

This method will be specifically described. Considering a straight line L11 passing through a point that internally divides the side AD and the side BC into α: (1-α) in the quadrangle ABCD that connects the theoretical positions of the points to be measured, such a straight line is α There are innumerable if the value of is changed, but the straight line L11 passing through the point M is uniquely determined, and therefore the value of α when the straight line L11 passes through the point M is obtained. Similarly, consider a straight line L12 that passes through a point that internally divides the sides AB and DC into β: (1-β), and obtain the value of β when the straight line L12 passes through the point M.
In this way, the values of α and β as the coordinate conversion parameters are specified (see FIG. 7A).

Next, using the values of α and β and the measured points a, b, c, and d, the side ad and the side bc in the quadrangle abcd are internally divided into α: (1-α), respectively. The straight line L21 passing through the point is also found, and the straight line L22 passing through the point that internally divides the side ab and the side dc into β: (1-β) is also obtained, and further, the intersection of the straight line L21 and the straight line L22. m (mx, my) is obtained, and the coordinates of this point m are set as the correction position of the component mounting location (see FIG. 7B). In addition, the difference in inclination between the straight line L11 and the straight line L12, and the straight line L12 and the straight line L22
The difference between the slopes of and is calculated, and the average is used as the slope of coordinate conversion.

Then, at the time of component mounting, the X-axis servomotor 15 and the Y-axis servomotor 9 are controlled so as to mount the component at the point m, which is the correction position, and according to the inclination of the coordinate conversion. The R-axis servomotors 19 and 20 are controlled so as to correct the angles of the parts.

Although FIG. 7 shows the case where the mounting position of one component is corrected, when mounting a plurality of components on the printed circuit board 3, the coordinates of the theoretical position of each mounting position are stored in advance, and The correction position and the slope of the coordinate conversion may be obtained for each location by the method shown in FIG.

Further, FIGS. 5 to 7 show the case where the theoretical position (point M) of the component mounting location is inside the quadrangle ABCD. In this case, α and β are values showing the internal division ratio. Although 0 <α <1 and 0 <β <1, the theoretical position (point M) of the component mounting position may be outside the quadrangle ABCD. In this case, one or both of α and β are It may be a value indicating a ratio. That is, for example, when the point M is located outside the quadrangle ABCD in the vertical direction, α is a value indicating the external division ratio (α> 1), and the sides AD and BC are α:
It suffices to find the value of α when a straight line passing through the point that is externally divided into (α-1) passes through the point M. Further, when the point M is laterally outside the quadrangle ABCD, β is the outside. A value indicating the ratio (β> 1) is set, and the sides AB and DC are respectively set to β: (β
The value of β may be obtained when the straight line passing through the point that is externally divided into -1) passes through the point M. The mounting position correction method described above is executed by the main arithmetic unit 32 and the like of the control device. FIG. 8 is a flow chart showing the processing such as control and calculation for the mounting position correction.

That is, when the process of this flowchart is started, first, the printed board 3 is carried in and fixed to the mounting work position on the base 1 of the mounting machine (step S1). Next, the mark count value i is set to "1" (step S2), and then the board recognition camera 27 moves to the theoretical position of the i-th (first is the first) fiducial mark 40 on the printed board 3. (Step S
3) The image of the fiducial mark 40 is picked up and its measured position is detected (step S4). Then, it is checked whether or not the mark count value i is 4 or less. If it is 4 or less, 1 is added to this value i, and then the steps S3, S
The process of 4 is repeated. Thus, the actually measured positions of the first to fourth fiducial marks 40 are sequentially detected, that is, the positions of the four points a, b, c, d shown in FIG. 6 are obtained.

Next, the mounted component count value j is set to "1" (step S2), and then it is checked whether or not the jth component mounting data exists (step S8). Then, when the component mounting data exists, the correction position of the component mounting position is obtained by the coordinate conversion calculation (step S9), and the component is mounted at the corrected mounting position (step S10). Further, after the mounted component count value j is added, the determination in step S8 is performed again, and the processes in steps S8 to S11 are repeated until the component mounting data no longer exists, so that the component should be mounted on the printed circuit board. With respect to the required number of components, the mounting positions are sequentially corrected and the components are mounted at the corrected positions.

In the calculation of the coordinate conversion in step S9,
Theoretical positions of the fiducial marks 40 stored in advance (positions of points A, B, C, D in FIGS. 5 and 7),
The measured position of each fiducial mark 40 obtained by the processing of steps S2 to S6 (point a in FIG. 6 and FIG. 7,
(b, c, d positions) and the theoretical position of the mounting location of the component included in the component mounting data stored in advance, the corrected position of the component mounting location is obtained by the method shown in FIG. .

According to the mounting position correction method as described above,
Four measured points with the fiducial mark 40 on the printed circuit board 3 are detected, and from the theoretical position and measured position of each measured point and the theoretical position of the component mounting position,
Since the corrected position of the component mounting position is required, the component can be mounted with high accuracy even when the printed circuit board is distorted or the like. This action will be described in detail below in comparison with the case where the measured points (fiducial marks) are 1, 2, and 3.

Factors on the printed circuit board side that cause the displacement of the component mounting position include displacement in the X and Y directions of the substrate, inclination (displacement in the rotational direction), expansion and contraction, distortion of the two-dimensional plane of the substrate, distortion, etc. In particular, if the material of the substrate is relatively easily deformed, such as glass evo, ceramics, flexible substrate, etc., expansion and contraction, distortion, etc. are likely to occur in addition to the positional displacement and inclination.

When the number of points to be measured is one, it is possible to know only the displacement in the X and Y directions of the substrate by comparing the X and Y coordinates of the actually measured position of that point with the coordinates of the theoretical position. However, it is impossible to know the displacement of the mounting position due to other factors.

When the number of points to be measured is two, each of the two points X and Y
Since four measurement data consisting of coordinates are obtained, it is possible to know the displacement, inclination, and elongation of the board in the X and Y directions based on the comparison between these and theoretical positions, but the displacement of the mounting position due to other factors. Can't know.

If there are three points to be measured, six measurement data consisting of the X and Y coordinates of the three points can be obtained.
Based on the comparison between these and the theoretical position, it is possible to know the displacement of the substrate in the X and Y directions, the inclinations of the X axis and the Y axis, and the elongations in the X direction and the Y direction. In other words, in addition to the displacement of the substrate, this can be known only for a specific deformation such as the rectangular substrate deforming into a parallelogram, but the displacement of the mounting position due to the general distortion of the substrate is known. It is not possible.

Therefore, in any of these cases, the component mounting position cannot be accurately corrected when the two-dimensional plane of the substrate is distorted or distorted.

On the other hand, in this embodiment, the measured point is set to 4
The parameters α and β indicating the relative positional relationship between the theoretical positions of the four points and the theoretical position of the component mounting position are obtained, and coordinate conversion is performed from the parameters α and β and the measured positions of each measured point. Since the correction position of the mounting position is obtained by performing the above, it is possible to accurately correct the component mounting position even when the substrate is expanded or contracted and the two-dimensional plane of the substrate is distorted or distorted.

In the above embodiment, the fiducial mark 40 to be measured is provided near each of the four corners of the printed circuit board.
The position of is not limited to this example, and may be set arbitrarily.

Further, the measured points (fiducial marks) may be set to five or more. In this case, for example, for each combination of four measured points, the theoretical position, the measured position, and the component mounting are respectively set. If the correction position is obtained from the theoretical position of the place by the method shown in FIG. 7 and the average value of these is obtained, the accuracy is further enhanced.

The detecting means for detecting the point to be measured is not limited to the board recognizing camera as in the above embodiment, and for example, a light emitting section for irradiating the printed board with light and a light receiving section for receiving the light reflected by the board. You may make it comprise a detection means with.

[0048]

As described above, according to the present invention, four or more points to be measured are set on the printed board, the positions of these points to be measured are measured, and the parts are mounted at the theoretical positions of the respective points to be measured. Since the correction position of the component mounting location is calculated based on the relative positional relationship of the theoretical positions of the locations and the actual measurement location of each measured point, even when the two-dimensional plane of the printed circuit board is distorted. Therefore, it is possible to properly obtain the corrected position of the component mounting position. Therefore, even if the printed circuit board is made of a material that is easily deformed, it is possible to accurately mount the component on the printed circuit board.

[Brief description of drawings]

FIG. 1 is a plan view showing a mounter to which a component mounting position correcting method according to the present invention is applied.

FIG. 2 is a front view showing a mounter to which the component mounting position correcting method according to the present invention is applied.

FIG. 3 is a block diagram showing a control system of the mounting machine.

FIG. 4 is a plan view showing a fiducial mark on a printed circuit board.

FIG. 5 is a diagram showing theoretical positions of four fiducial marks and theoretical positions of component mounting positions.

FIG. 6 is a diagram showing measured positions of four fiducial marks.

7A and 7B are diagrams showing a method of obtaining a correction position of a component mounting position.

FIG. 8 is a flowchart showing processing such as control and calculation for mounting position correction.

[Explanation of symbols]

 3 Printed circuit board 5 Head unit 40 Fiducial mark A, B, C, D Theoretical position of measured point M Theoretical position of component mounting location a, b, c, d Actual measured position of measured point m Correction of component mounting location position

Claims (2)

[Claims] 1. A mounting machine for picking up a component from a component supply unit by a component mounting head and mounting the component at a component mounting location on a printed circuit board, wherein four or more measured points are set on the printed circuit board. The theoretical position of the point to be measured and the theoretical position of the component mounting location are stored in advance, and each of the points to be measured is detected by the detecting means provided in the component mounting head to measure these positions. Based on the parameters obtained from the relative positional relationship of the theoretical position of the component mounting position with respect to the theoretical position of the measured point, and the measured position of each measured point measured by the detecting means, A mounting position correction method for a mounting machine, which comprises calculating a correction position. 2. The position of each of the measured points is measured by imaging the fiducial marks attached to the measured points of four or more locations on the printed circuit board by the imaging means provided in the component mounting head. The mounting position correction method for a mounting machine according to claim 1, wherein