JP2000353899A - Mounting method of electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mounting method of electronic part in which the mounting cost can be reduced while enhancing the efficiency. SOLUTION: In a mounting method of electronic part where a board for mounting an electronic part is recognized by means of a camera and a mounting head is positioned relatively to the board based on the recognition results before the electronic part is mounted on the board, a plate jig 3' for measurement of smaller size than the mounting area A is employed when positional shift of the optical coordinate system in a camera is detected by picking up the image of the plate jig 3' mounted on the mounting area A. When an image is picked up by moving the plate jig 3' sequentially, the image pick up ranges are overlapped partially, a plurality of positional shift data are determined by recognizing it a plurality of times before and after movement for the overlapped region LZ and then the error between the positional shift data generated by moving the plate jig 3' is corrected based on the plurality of positional shift data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an electronic component on a substrate.

[0002]

2. Description of the Related Art In an electronic component mounting apparatus, a mounting head that picks up an electronic component from an electronic component supply unit is moved to a position on a substrate to be mounted, and is mounted. An electronic component mounting apparatus generally includes a camera for recognizing a substrate. The camera detects the position of the substrate by capturing an image of the substrate, and performs positioning when mounting the electronic component based on the position detection result. That is, the alignment at the time of mounting is performed with reference to the optical coordinate system of the camera.

However, the position of the optical system coordinates of the camera for board recognition is not always at the position indicated on the control data, and a displacement occurs due to various factors.
This displacement is not always uniform due to a mechanism error of the moving table for moving the camera, and indicates a unique displacement at each position in the mounting area. For this reason, when starting up the mounting apparatus, it is necessary to perform calibration for obtaining these positional deviation amounts for each position in the mounting area.

As a calibration method, a method using a plate jig for measurement is known. This plate jig is provided with reference marks of a predetermined accuracy in a lattice shape on a plate surface whose shape and dimensions are manufactured according to a reference value so as not to cause a positioning error, and these reference marks are imaged by a camera. Thus, the amount of positional deviation at each grid point in the mounting area, that is, the amount of positional deviation between the optical coordinate system of the camera and the actual optical coordinate system of the camera on the control data is obtained.

[0005]

However, in the above method, if the size of the target board is increased, that is, if the mounting area of the mounting apparatus is widened, a plate jig according to the size must be prepared. did not become. Since this plate jig requires high precision, the cost increases as the plate jig becomes larger. Furthermore, large plate jigs are difficult to handle at the time of work, and time is required at the time of calibration work, and the burden on the operator is heavy. As described above, the conventional electronic component mounting has a problem that the calibration work requires labor and high cost when a large-sized substrate is targeted, which hinders a reduction in mounting cost and an improvement in efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of mounting an electronic component which can reduce mounting cost and improve efficiency.

[0007]

According to a first aspect of the present invention, there is provided a method of mounting an electronic component, wherein a board on which the electronic component is mounted is recognized by a board recognition camera, and a mounting head picking up the electronic component is used as a result of the recognition. An electronic component mounting method for mounting the electronic component on a substrate by positioning the electronic component relative to the substrate based on the image of a plate jig for measurement placed in a mounting area by the mounting head. A positional deviation detecting step of detecting a positional deviation between the optical coordinate system of the camera and the actual optical coordinate system of the camera on the control data for each predetermined grid point; and correcting the electronic component by correcting the positional deviation. Mounting on a substrate, and in the displacement detection step, the imaging range is partially overlapped when the plate jigs smaller in size than the mounting area are sequentially moved in the mounting area for imaging. The superimposed range is recognized a plurality of times before and after the movement to obtain a plurality of displacement data, and an error between the displacement data generated by the movement is corrected based on the plurality of displacement data. I did it.

According to the present invention, when moving a plate jig having a size smaller than the mounting area to perform imaging, the imaging range is partially overlapped, and the overlapping range is determined based on a plurality of areas before and after the movement. Times, a plurality of displacement data are obtained, and an error between the displacement data generated by the movement is corrected based on the plurality of displacement data, whereby the mounting area is reduced by a plate jig smaller than the mounting area. Can cover the entire range within.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIGS. 1 and 2A are plan views of an electronic component mounting apparatus according to an embodiment of the present invention, and FIG. 2B is an image diagram for board recognition of the electronic component mounting apparatus, and FIGS.
(B) is a plan view of a mounting area of the electronic component mounting apparatus, FIG. 4 is a flow chart of the XY table position shift measurement, and FIG.
(A), (b), (c) is an explanatory view of a process of detecting a displacement in the electronic component mounting method.

First, the structure of the electronic component mounting apparatus will be described with reference to FIG. In FIG. 1, a transport path 2 is provided on a base 1, and the transport path 2 transports a substrate 3 loaded from a previous process and positions the substrate 3 at a position where electronic components are mounted. Conveyance path 2
The moving table 4 is disposed beside the. The moving table 4 is configured by combining a Y table 5 and an X table 6, and a mounting head 7 is mounted on the X table 6 via a moving plate 6a. By driving the moving table 4, the mounting head 7 moves horizontally, picks up electronic components from an electronic component supply unit (not shown), mounts them on the substrate 3, and mounts them.

A camera 8 is mounted on the moving plate 6a, and the camera 8 moves integrally with the mounting head 7.
The position of the substrate 3 is recognized by driving the moving table 4 to move the camera 8 onto the substrate 3 and imaging the recognition marks 3 a provided at each diagonal position of the substrate 3 with the camera 8. Then, based on the position recognition result, the substrate 3
Is detected, and when the electronic component is mounted, the displacement is corrected and the moving table 4 is driven.

Next, with reference to FIG. 2, a description will be given of the calibration performed for detecting the amount of displacement of the optical coordinate system of the camera of the electronic component mounting apparatus. This calibration is performed at the time of starting up the electronic component mounting apparatus or at the time of maintenance work. As shown in FIG. 2A, the moving table 4 has a unique orthogonal coordinate system XY. However, the crossing angle θ between the X and Y axes is not a perfect right angle due to a mechanical error in a state where the X table 6 and the Y table 5 are joined. The X table 6 and the Y table 5 also have a pitch error of the ball screw and a variation in linearity of the guide portion.

For this reason, the position indicated on the control data does not always coincide with the position at which the camera is actually driven and moved by the moving table 4, and the actual camera at the time of board recognition performed at the time of mounting electronic components. 8 and the position of the camera 8 on the control data. This displacement is not constant, and the moving table 4
Is different depending on each position of the mounting area of the mounting head 7, ie, the mounting area of the mounting head 7.

Therefore, calibration for correcting these positional deviations, that is, the amount of positional deviation between the optical coordinate system of the camera and the actual optical coordinate system of the camera on the control data is detected. In this calibration, the shape and dimensions are manufactured according to the reference value so as not to cause a positioning error, and as shown in FIG. 2A, a recognition mark 3b as a reference mark is formed on the surface as a grid at a predetermined position and a predetermined accuracy. Is used.

First, the moving table 4 is driven, and the camera 8
Is moved onto the plate jig 3 'positioned at a predetermined position, and the recognition marks 3b are sequentially imaged to recognize the positions of the recognition marks 3b. At this time, the movement of the camera 8A is controlled on the control data so that the origin 0 of the optical coordinate system coincides with the center of the recognition mark 3b. The origin 0 does not always coincide with the center of the recognition mark 3b. FIG.
(B) is an image diagram when position recognition is performed on the recognition mark 3bn of the plate jig 3 ′. In this case, a position shift of Δxn, Δyn with respect to the origin 0 of the optical coordinate system is detected for the recognition mark 3bn (center coordinates (Xn, Yn) in the machine coordinate system) by position recognition.

That is, coordinates (Xn, Y) in the machine coordinate system
When electronic components are mounted in the vicinity of (n), Δxn and Δyn are further added to the board position recognized by the camera 8.
Must be corrected. Therefore, when starting up the assembly of the electronic component mounting apparatus, the positional deviation amounts (Δxn, Δyn) are obtained for all the recognition marks 3b, so that the coordinate system X-
It is possible to obtain position correction amount data for correcting a position shift unique to Y.

FIG. 3 shows a plate jig 3 'used for calibration when the target mounting area A is large. In this case, as shown in FIG. 3A, the width B and the length L of the mounting area A are larger than the width b and the length 1 of the plate jig 3 ′. It cannot cover the whole range. Therefore, as shown in FIG. 3B, the mounting area A is divided into a plurality of areas according to the size of the plate jig 3 ', and the plate jig 3' is calibrated while sequentially moving from one side for each area. Perform the work. Hereinafter, this calibration work will be described with reference to the flow of FIG.

First, the plate jig 3 'is set at a predetermined position in the mounting area A (ST1). Here, first, FIG.
It is set in the first area A1 shown in (b). Next, the recognition marks 3b of the plate jig 3 'are sequentially imaged to detect the position (ST2). Then, based on the detected position of each recognition mark, the amount of displacement of the optical coordinate system of the camera at the position of each recognition mark 3b ((Δxn, Δy described above)
n)) is obtained. This displacement data is stored in the storage unit (ST3). Next, it is determined whether or not the position measurement has been completed for the entire range of the mounting area A (ST4). If the measurement has not been completed, the jig plate 3 'is moved to the next measurement position (ST5). And S
Returning to T1, the same imaging and position recognition are repeated.

Here, the plate jig 3 'is mounted on the mounting area A.
When the image is sequentially moved within the area, the second area A2
Is set such that the moving position partially overlaps the first area A1 by a predetermined overlapping range LZ. That is, by partially overlapping the imaging range, the overlapping range LZ is imaged twice before and after the movement from the first area A1 to the second area A2.

If the measurement has been completed for the entire area of the mounting area A in ST4, that is, the first area A1,
When the measurements of the second area A2 and the third area A3 have all been completed, the displacement data at the respective measurement positions are combined to determine the displacement of the entire area of the mounting area A (ST6).

Regarding the process of synthesizing the displacement data,
This will be described with reference to FIG. FIG. 5A shows the overlapping range LZ before and after the movement of the plate jig 3 ′. In the state before the movement, among the reference marks of the plate jig 3 ′, the recognition marks 3b (indicated by solid lines) belonging to the recognition mark row L1 in the rightmost row are located in the overlapping range LZ,
In this state, it is recognized by the camera 8. After the movement of the plate jig 3 ', the recognition marks (shown by broken lines) 3b belonging to the leftmost recognition mark row L2 among the reference marks are located in the superposition range LZ in the superposition range LZ.
Similarly, an image is taken by the camera in this state.

When the plate jig 3 'is moved, the recognition marks 3b belonging to the leftmost recognition mark row L2 after the movement.
Does not always move so as to coincide with the recognition mark 3b belonging to the rightmost recognition mark row L1 before the movement. Generally, as shown in FIG. 5A, the recognition mark row L1 and the recognition mark row L2 Does not match. That is, the position recognition result of the recognition mark 3b within the superimposition range LZ obtained in this state is given as two different positional deviation data before and after the movement from the first area A1 to the second area A2. .

The difference between the two pieces of displacement data becomes a displacement detection error resulting from the movement of the plate jig 3 '. In other words, the positional deviation data for each recognition mark obtained when the same plate jig 3 ′ is set in the first area A1, and each recognition mark obtained when the same plate jig is set in the second area A2. The above-mentioned difference exists for all the individual positional deviation amounts between the positional deviation data of the first and second positions.

However, since the purpose of the calibration is to determine the amount of positional deviation peculiar to each position in the entire range within the mounting area A, the mounting area A is divided and the plate jig 3 'is moved. It is necessary to remove the difference between the set of misalignment data. The data conversion processing performed for this purpose will be described. This data conversion processing is performed by using the positional deviation data obtained before the movement of the plate jig 3 ′ for the recognition marks belonging to the recognition mark row L1 shown in FIG. 5A and the position obtained after the movement of the recognition mark row L2. The data conversion process is performed to superimpose the shift data so that the shift data has the same value on the numerical data.

FIG. 5B schematically shows the data conversion process. In FIG. 5B, a black point on the recognition mark row L1 and a white point on the recognition mark row L2 are data points indicating the positional deviation at each position, and each data point is the position of the recognition mark 3b at that position. (Δxn, Δyn) obtained by detecting
Is supported. At the time of data conversion, first, FIG.
As shown in FIG. 7, the difference between the data point P1 indicating the displacement of the lowest recognition mark belonging to the recognition mark row L1 and the data point P2 indicating the displacement of the lowest recognition mark belonging to the recognition mark row L2. Error data lx and ly indicating the following are obtained.

Next, the data of all the positional deviation amounts (Δxn, Δyn) obtained in the second area A2 are corrected by the error data lx, ly. That is, as shown in (a) of FIG.
Is moved in parallel so as to overlap the data point P1. Here, each of the recognition mark strings L1,
The difference between the data points P1 and P2 at the lowermost position of L2 is used as error data, but the differences are obtained for all corresponding data points of the recognition mark strings L1 and L2, respectively.
The average value may be used as error data.

As a result, the data point P2 is superimposed on the data point P1, as shown in FIG. 5 (b).
Next, a data conversion process for superimposing the recognition mark sequence L1 and all data points belonging to the recognition mark sequence is performed. Here, as shown in (b) of FIG. 5B, the intersection angle θ between the recognition mark rows L1 and L2 is obtained, and the second area A2
(Xn, Δy)
For the data of n), data conversion for rotating by θ about the point P1 is performed.

By this data conversion processing, as shown in FIG. 5 (C), for the recognition marks belonging to the rightmost column L1 of the plate jig 3 ', the displacement data obtained before the movement of the plate jig 3' The position shift data obtained after the movement for the leftmost column L2 is superimposed so as to have the same value on the numerical data, and the respective recognition marks separately obtained before and after the movement of the plate jig 3 ′ are obtained. Can be combined with the same positional deviation data as obtained by using one plate jig.
That is, based on a plurality of pieces of displacement data obtained before and after the movement, an error between the pieces of displacement data generated by the movement is corrected to obtain one piece of the displacement data.

Although the present embodiment has been described with respect to an example in which the superimposition range LZ includes only one row of the recognition mark L L1 or L2, the superimposition range LZ may include a plurality of recognition mark rows. Range setting may be performed. In this case, an average value of the differences between the corresponding recognition mark strings is obtained, and the above-described data conversion is performed using the average value.

Then, the same data conversion processing is performed on the displacement data obtained for the second area A2 and the displacement data obtained for the third area.
As a result, displacement data indicating the displacement amount of the optical coordinate system of the camera 8 at the position corresponding to each recognition mark 3b of the plate jig 3 'is obtained over the entire range of the mounting area A.

Returning to FIG. 4, the positional deviation data obtained as described above is stored as a positional correction amount at the time of mounting (ST7). When the electronic component is mounted on the board by the mounting head 7 in the mounting operation of the electronic component, the drive axis of the moving table 4 is controlled in consideration of the position correction amount.

As described above, according to the present invention, in the calibration for measuring the displacement of the moving table 4, the plate jig 3 'having a size about one third of the required mounting area A is used. With this, calibration with sufficient accuracy can be performed. That is,
Even when the mounting area A corresponding to a large-sized substrate is targeted, it is not necessary to prepare the plate jig 3 ′ each time, and the plate jig of the reference size is sequentially moved to be used for general purpose. be able to. Therefore, it is not necessary to prepare a large-sized plate jig at a high price, and the cost can be reduced. In addition, since the small-sized plate jig is easy to handle, the calibration work can be performed efficiently and efficiently. It can be carried out.

[0033]

According to the present invention, when a plate jig having a size smaller than the mounting area is moved for imaging, the imaging range is partially overlapped, and the overlapping range is determined before and after the movement. A plurality of misalignment data is obtained by recognizing the plurality of misalignment data, and errors between the misalignment data generated by the movement are corrected based on the plurality of misalignment data. Can cover the entire area within the mounting area, eliminating the need to prepare a large, expensive plate jig, reducing costs and simplifying handling during work to improve work efficiency. .

[Brief description of the drawings]

FIG. 1 is a plan view of an electronic component mounting apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view of an electronic component mounting apparatus according to one embodiment of the present invention; FIG. 2B is an image diagram for board recognition of the electronic component mounting apparatus according to one embodiment of the present invention;

3A is a plan view of a mounting area of the electronic component mounting apparatus according to one embodiment of the present invention; FIG. 3B is a plan view of a mounting area of the electronic component mounting apparatus according to one embodiment of the present invention;

FIG. 4 is a flowchart of an XY table displacement measurement according to an embodiment of the present invention.

FIG. 5A is a diagram illustrating a process of detecting a displacement in an electronic component mounting method according to an embodiment of the present invention; and FIG. 5B is a diagram illustrating a process of detecting a displacement in an electronic component mounting method according to an embodiment of the present invention. (C) Process explanatory view of position shift detection in the electronic component mounting method according to one embodiment of the present invention

[Explanation of symbols]

 3 Substrate 3 'Plate jig 3b Recognition mark 4 Moving table 7 Mounting head 8 Camera A Mounting area L1, L2 Recognition mark row

Claims (1)

[Claims] An electronic component is mounted on a substrate by recognizing a substrate on which the electronic component is mounted by a camera for recognizing the substrate, and a mounting head picking up the electronic component is positioned relative to the substrate based on the recognition result. A mounting method for mounting an electronic component on a substrate, wherein an image of a measurement plate jig mounted on a mounting area by the mounting head is imaged, and the optical coordinates of the camera on control data for each predetermined grid point. A position shift detecting step of detecting a position shift amount between the system and an actual optical coordinate system of the camera, and a step of mounting the electronic component on a substrate by correcting the position shift amount, in the position shift detection step, The imaging range is partially overlapped when the plate jig smaller in size than the mounting area is sequentially moved within the mounting area to perform imaging, and the overlapping range is a plurality of before and after the movement. Obtains a plurality of displacement data confirmed, the mounting method of electronic components and corrects the error between the position error data mutually generated by the movement on the basis of the plurality of position error data.