JP2004195473A - Laser beam machining method and laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method and a laser beam machining apparatus for enhancing the positioning accuracy and performing machining with high accuracy. <P>SOLUTION: The laser beam machining method to correct the irradiation position at which a work 53 is irradiated with laser beams emitted from a laser beam oscillator 41 via a galvano-scanner 54 and an fθ lens 48 comprises an irradiation step of irradiating the laser beams at a plurality of reference irradiation positions, an error measurement step of measuring the error between a plurality of irradiation points obtained from the irradiation step and the reference irradiation position, and a correction step of correcting the emission timing of the laser beams emitted from the laser beam oscillator on the basis of the error obtained in the error measurement step. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing method and a laser processing apparatus, and more particularly, to a laser processing method and a laser processing apparatus for improving positioning accuracy and processing a processing object with high accuracy.
[0002]
[Prior art]
Conventionally, a laser processing apparatus includes an XY stage for moving a workpiece to be moved horizontally. By moving the workpiece with the XY stage, processing can be performed by irradiating a laser beam to a desired processing position. it can. Furthermore, in addition to the XY stage, a pair of galvano scanners are used to oscillate laser light emitted from the laser oscillator in the X-axis direction and the Y-axis direction, thereby achieving high speed and high accuracy within a predetermined range of the workpiece. Laser processing can be performed.
[0003]
Here, a laser processing apparatus using a galvano scanner will be described with reference to the drawings.
[0004]
FIG. 1 is a diagram illustrating a configuration example of a conventional laser processing apparatus including a galvano scanner.
[0005]
A laser processing apparatus 10 in FIG. 1 includes a laser oscillator 11, an amplifier 12 for controlling the movement and driving of the galvano scanner, a control unit 13 for controlling the laser oscillator 11 and the amplifier 12, and a first galvano driving system 14. And a first galvano mirror 15, a second galvano drive system 16, a second galvano mirror 17, and an fθ lens 18. The first galvano drive system 14, the first galvano mirror 15, the second galvano drive system 16, and the second galvano mirror 17 constitute a galvano scanner 20.
[0006]
The control unit 13 outputs to the amplifier 12 a control signal for controlling the emission timing of the laser light from the laser oscillator 11 and the first galvano drive system 14 and the second galvano drive system 16. 12 transmits a signal to the first drive system 14 and the second drive system 16 based on the control signal. The drive system uses the galvanometer mirrors 15 and 17 provided in each drive system in response to a signal from the amplifier 12 to oscillate the laser light in the X-axis direction and the Y-axis direction, adjust the optical path of the laser light, and perform fθ The light enters the lens 18. The fθ lens 18 performs processing by irradiating a laser beam perpendicularly to a processing target at a desired processing point according to the angle of the incident laser light.
[0007]
By using the galvano scanner as described above, high-speed and high-precision processing is possible.
[0008]
By the way, it is known that in the laser processing apparatus provided with the galvano scanner and the fθ lens described above, a positional shift due to optical system distortion occurs. For this reason, conventionally, trial machining is performed when the apparatus is in operation, and it is confirmed whether or not machining is accurately performed at a predetermined position, and correction is performed when a positional deviation occurs. Here, conventional correction processing will be described with reference to the drawings.
[0009]
FIG. 2 is a diagram illustrating an example of a correction process in the laser processing apparatus of FIG.
[0010]
The laser beam irradiated from the laser oscillator 11 is irradiated perpendicularly to the workpiece 19 via the second galvanometer mirror 17 and the fθ lens 18. When correcting a processing point, as shown in FIG. 2, a plurality of reference irradiation positions are irradiated with a laser beam in a matrix, and a deviation (error) from a reference value corresponding to each irradiation point is measured. Then, correction is performed for each irradiation point based on the deviation amount. This method is called a teaching method.
[0011]
Next, the contents of the above-described optical system distortion will be described with reference to the drawings.
[0012]
FIG. 3 is a diagram illustrating an example of an optical system distortion that occurs during conventional laser processing. Here, a diagram is shown in which the outer peripheral portions of the processing points processed into a matrix are connected by lines so that the state of distortion becomes clear. Moreover, the dotted line has shown the outer peripheral part of the irradiation position used as a some reference | standard.
[0013]
The distortion shown in FIG. 3A is a distortion referred to as pincushion distortion generated from the relationship between the control angle of the scan mirror and the processing position. Further, the distortion shown in FIG. 3B is a distortion called linearity distortion generated when a plurality of lenses constituting the fθ lens deviate from a design value. Further, the distortion shown in FIG. 3C is a combined distortion in which the pincushion distortion and the linearity distortion are combined. In actual processing, the processing distortion shown in FIG. 3C is generated, and this causes misalignment. Therefore, the above-described teaching method or the like is used to correct this misalignment.
[0014]
However, with the correction method based on the teaching method, only correction accuracy up to about 20 μm can be obtained. Therefore, as a method for correcting the misalignment, for example, a method already filed and presented by the present applicant can be used (see, for example, Patent Document 1).
[0015]
In Patent Document 1, correction of the irradiation position in the laser beam is performed by providing test data for performing test processing on a test workpiece at each point in a matrix at a first pitch. The image processing apparatus captures an image of the processed region after the test processing, measures a deviation amount from the processing center position and the true processing center position at each point in the matrix shape, and outputs measurement data for each point. The arithmetic processing unit performs a predetermined interpolation calculation using the measurement data for each point, sets a plurality of interpolation positions with a second pitch smaller than the first pitch between the matrix-like points, A correction data file is created with these interpolation positions and the true machining center position at each of the matrix points as correction data. Based on the correction data file, the positional deviation is corrected to realize high-precision machining.
[0016]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-301052
[Problems to be solved by the invention]
By the way, in a laser processing apparatus using a galvano scanner, when correction with higher accuracy is performed, correction for a control system (amplifier) in consideration of overshoot is required in addition to correction of an optical system. That is, when the positioning accuracy of the galvano scanner is deteriorated, the laser beam irradiation processing waiting time (settling time) from the laser oscillator is considered in consideration of the overshoot (excessive overshoot amount) time in the movement of the galvano scanner, that is, the laser beam By automatically setting the emission timing to an appropriate time, positioning accuracy and processing accuracy can be improved.
[0018]
In the conventional adjustment of the amplifier, when the position accuracy deteriorates, the control command parameter relating to the movement of the machining position is adjusted by manual operation by the worker each time. Here, the adjustment of the amplifier means adjusting the variable resistance value of the servo amplifier in the galvano scanner, and the control gain and the like can be adjusted by this adjustment work.
[0019]
Further, when the adjustment is performed manually, it is necessary to temporarily stop the laser processing, so that useless time is required and productivity is lowered. Furthermore, since the setting changes depending on the skill level of the person who performs manual adjustment, a problem in accuracy arises.
[0020]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a laser processing method and a laser processing apparatus for improving positioning accuracy and processing a highly accurate workpiece.
[0021]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs means for solving the problems having the following characteristics.
[0022]
According to a first aspect of the present invention, there is provided a laser processing method for correcting an irradiation position in which a laser beam emitted from a laser oscillator is irradiated onto a processing object via a galvano scanner and an fθ lens. Obtained by an irradiation stage for irradiating a reference irradiation position, an error measurement stage for measuring an error between a plurality of irradiation points obtained by the irradiation stage, and the reference irradiation position, and the error measurement stage. And a correction stage for correcting the emission timing of the laser beam emitted from the laser oscillator based on the error.
[0023]
According to the first aspect of the present invention, in consideration of the overshoot in the movement of the galvano scanner, the emission timing (irradiation processing waiting time (settling time)) is automatically set to an appropriate time, thereby positioning accuracy and processing. Accuracy can be improved.
[0024]
The invention described in claim 2 is characterized in that, in the correcting step, optical system distortion is corrected before correcting the laser beam emission timing.
[0025]
According to the second aspect of the present invention, the laser beam emission timing can be corrected with higher accuracy.
[0026]
According to a third aspect of the present invention, in the irradiation step, the error measurement step, and the correction step, an error between the plurality of irradiation points obtained by the error measurement step and the reference irradiation position is obtained. It is characterized in that it is repeated until it becomes a predetermined threshold value or less.
[0027]
According to the third aspect of the present invention, it is possible to perform correction with higher accuracy and provide laser processing with improved stability.
[0028]
According to a fourth aspect of the present invention, there is provided a laser processing apparatus for correcting an irradiation position in which a laser beam emitted from a laser oscillator is irradiated onto a processing object via a galvano scanner and an fθ lens. Obtained by an irradiation unit that irradiates a reference irradiation position, an error measurement unit that measures an error between a plurality of irradiation points obtained by the irradiation unit, and the reference irradiation position, and the error measurement unit And a correction unit that corrects the emission timing of the laser beam emitted from the laser oscillator based on the error.
[0029]
According to the fourth aspect of the present invention, in consideration of overshoot in the movement of the galvano scanner, the emission timing (irradiation processing waiting time (settling time)) is automatically set to an appropriate time, thereby positioning accuracy and processing. Accuracy can be improved.
[0030]
The invention described in claim 5 is characterized in that the correction unit corrects optical system distortion before correcting the emission timing of the laser beam.
[0031]
According to the fifth aspect of the present invention, it is possible to correct the irradiation timing of the laser light with higher accuracy.
[0032]
In the invention described in claim 6, the irradiation unit, the error measurement unit, and the correction unit have an error between the plurality of irradiation points obtained by the error measurement unit and the reference irradiation position. It is characterized in that it is repeated until it becomes a predetermined threshold or less.
[0033]
According to the sixth aspect of the present invention, it is possible to provide a laser processing apparatus capable of performing correction with higher accuracy and having improved stability.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
The present invention corrects for distortion of the optical system of the lens, and further performs high-precision laser processing by automatically correcting the emission time of the laser light from the laser oscillator in consideration of the settling time in the movement of the carbano scanner. Is possible.
[0035]
In particular, when the positioning accuracy of the galvano scanner is deteriorated, the laser beam irradiation processing waiting time (settling time) from the laser oscillator, that is, the laser beam emission timing is set to an appropriate time in consideration of the overshoot time in the movement of the galvano scanner. The positioning accuracy and the processing accuracy are improved by automatically setting to. Conventionally, the above work has been performed manually, so that productivity and machining accuracy have been reduced. However, automatic setting improves the speed and productivity with improved operability. A laser processing apparatus is provided.
[0036]
The above-described emission timing correction will be described with reference to the drawings. FIG. 4 is a diagram illustrating an example of overshoot in position movement. Here, the curve in FIG. 4 shows how the position of the conventional galvano scanner described above changes with time.
[0037]
In FIG. 4, the galvano scanner moves from the position P1 to the target setting position P2 in accordance with a movement command from the control unit, but after reaching the target setting position (t1 in FIG. 4), the overshoot movement is performed. . Thereafter, the movement is performed until a predetermined allowable (error) range with respect to the target setting position P2 is reached. The settling time until it falls within the range is t2. Actually, since laser light is emitted from the laser oscillator at time t1, a position shift occurs due to overshoot, and laser processing is performed in a state where accurate correction is not performed.
[0038]
Therefore, in order to solve this problem, the present invention repeatedly performs correction while gradually increasing the settling time t from t1 in consideration of overshoot so that the position of the galvano scanner is within the set error range, An appropriate settling time is determined, and control is performed so that laser light is emitted from the laser oscillator when the galvano scanner is positioned at the settling time. The correction of the control system described above is performed after the optical system correction of the lens is performed, so that the settling time can be set accurately.
[0039]
Next, embodiments of the present invention will be described with reference to the drawings.
[0040]
FIG. 5 is a diagram showing a first embodiment of a laser processing apparatus according to the present invention.
[0041]
5 includes a laser oscillator 41, an amplifier 42 for controlling movement and driving of the galvano scanner, a control unit 43, a first galvano drive system 44, and a first galvano mirror 45. The second galvano drive system 46, the second galvano mirror 47, the fθ lens 48, the processing stage 49, the CCD camera 50, the error measurement unit 51, and the correction unit 52 are configured. . The processing object 53 is placed on the processing stage 49. The first galvano drive system 44, the first galvano mirror 45, the second galvano drive system 46, and the second galvano mirror 47 constitute a galvano scanner 54. The processing object 53 can be a printed circuit board, a green sheet, or the like.
[0042]
The control unit 43 controls the operation timing of the laser oscillator 41, the amplifier 42, and the processing stage 49.
[0043]
In order to perform processing on the processing object 53, the control unit 43 moves the processing stage 49 in the X axis direction and the Y axis direction to perform positioning. Further, the control unit 43 outputs a control signal for driving the carbano drive system to the amplifier 42. The amplifier 42 outputs drive signals to the first galvano drive system 44 and the second galvano drive system 46 based on a control signal from the control unit 43. The laser light emitted from the laser oscillator 41 is reflected by the first galvanometer mirror 45 installed in the first galvano drive system 44, and further the laser beam is incident on the fθ lens 48 by the second galvanometer mirror 47. Reflection is performed. In addition, since the control signal output to the galvano drive system from the amplifier 42 is output for each of a plurality of reference irradiation positions with which the workpiece 53-1 is irradiated, correction is also performed for each irradiation position.
[0044]
The fθ lens 48 includes a plurality of optical lenses, and irradiates the laser beam perpendicularly to the workpiece 53 even with respect to laser light having an incident angle. The laser beam output from the fθ lens 48 is irradiated to the workpiece 53-1, and laser processing is performed.
[0045]
Next, the control unit 43 measures the error between a plurality of reference irradiation positions in a matrix and actual irradiation points, so that the processing stage 49-2 starts from the position of the processing stage 49-1. Then, the CCD camera 50 shoots the irradiation points processed into a matrix.
[0046]
In the above description, the processing stage is moved. However, the present invention is not limited to this. The CCD camera 50 is installed on the same axis as the laser optical path output from the fθ lens 48, and the irradiation position is set simultaneously with the irradiation. You may make it the structure which image | photographs. Further, it is possible to easily realize a configuration in which the CCD camera 50 is moved to the processing stage 49-1. In this embodiment, the processing stage 49-2 is moved, processing holes are made one by one in the field of view of the fixed CCD camera 50, and the image processing is performed by the camera. The processing position in the X-axis and Y-axis position coordinate system of the processing stage can be calculated from the result of the image processing.
[0047]
Image information photographed by the CCD camera 50 is input to the error measurement unit 51, and error measurement between the reference irradiation position and the actually irradiated irradiation point is performed for each irradiation point irradiated in a matrix. . The type of camera is not limited to a CCD camera, and any camera can be used as long as it can be measured by the error measurement unit 51 from an acquired image, and another high-speed camera can be used.
[0048]
The error information output by the error measurement unit 51 is input to the correction unit 52. The correction unit 52 generates an irradiation correction value at each point from the error at each irradiation point, and sets a settling time. To the control unit 43.
[0049]
Here, the contents of correction will be described. First, in order to correct the optical system, the fθ lens distortion is corrected. In this embodiment, it is assumed that the fθ calibration for the fθ lens is provided. The fθ calibration is a reference irradiation position corresponding to each point of the matrix using the CCD lens 50 in the XY table (processing stage) coordinate system, which is processed in a matrix by the carbano scanner 54. The lens aberration is measured and corrected by measuring the positional deviation (error). The fθ calibration is repeatedly performed until the error from the irradiation position serving as the reference of each irradiation point becomes equal to or less than a predetermined threshold value.
[0050]
Next, the settling time in the movement of the galvano scanner 54 is corrected. In other words, the threshold for the preset error is set so that the time (setting time) that the position of the movement of the galvano scanner 54 is within an allowable range (settling time) is appropriate for the emission timing of the laser light from the laser oscillator 41. The correction process is repeated until the value becomes lower than the value.
[0051]
Further, a correction method for determining an appropriate time for the laser beam emission timing is that the laser beam emission timing from the laser oscillator is set to a predetermined value (time) of the parameter (time) of the laser irradiation waiting time of the laser oscillator. 4 is gradually extended from t1), and irradiation and error calculation are repeated until the irradiation process of the laser beam at the reference irradiation position and the error from the irradiation point become equal to or less than a predetermined threshold.
[0052]
The control unit 43 controls the laser oscillator 41, the amplifier 42, and the processing stage 49 based on the signal generated by the correction unit 52, and performs control to improve the positioning accuracy and perform desired processing.
[0053]
Accordingly, it is possible to provide a laser processing apparatus that enables quick error correction and improves productivity associated with improvement in speed and operability.
[0054]
In the above description, the correction process is repeatedly performed until the threshold value is equal to or lower than a preset threshold value. However, the present invention is not limited to this. Correction processing can also be performed until Thereby, the correction time can be set.
[0055]
Next, the correction processing procedure in the present invention will be described using a flowchart.
[0056]
FIG. 6 is a flowchart of an example showing the flow of correction processing in the present invention.
[0057]
First, laser processing is performed by irradiating a plurality of reference irradiation positions of the processing object 49 with a laser beam (S01). After completion of S01, the irradiation point is photographed for each point by the CCD camera 50 and the irradiation point is measured (S02). Next, an error from the reference point is calculated for each point (S03). Here, as an error calculation method, spline interpolation, a linear interpolation method that determines the value of a point in a rectangle surrounded by a certain four points by the ratio of the distance and the value of the four corner points, or the like is used. Can do.
[0058]
Next, it is determined whether the error for each processing point processed into a matrix calculated in S03 is smaller than a preset threshold A1 (S04). Here, it can be said that the threshold A1 corresponds to the correction accuracy in correcting the optical system distortion. In the determination, if the correction value is equal to or less than the threshold value A1 (YES in S04), it is assumed that the optical system distortion has been corrected. If the correction value is larger than the threshold value A1 (NO in S04), a correction value for the optical system distortion is generated to correct the optical system distortion (S05), and an error is set in advance from S01. Repeat until threshold A or less.
[0059]
For correction, position correction of the galvano scanner 54 is set as a parameter for the control unit 43 for each processing point processed into a matrix. Further, the threshold value A1 is preferably about 20 μm from the repetition time in correction.
[0060]
Next, it is determined whether the error for each processing point processed into a matrix calculated in S03 is smaller than a preset threshold A2 (S06). Here, it can be said that the threshold A2 corresponds to the correction accuracy in the correction of the emission timing of the laser light from the laser oscillator due to the overshoot of the galvano scanner 54. If the error for each machining point calculated in S03 is equal to or smaller than threshold A2 (YES in S06), the correction process is terminated.
[0061]
If the error is smaller than the threshold value A2 (NO in S06), the settling time is corrected according to the timing of the galvano scanner 54 (S07), and the process returns to S01 and is repeated. Here, the correction of the settling time is equivalent to the correction of the laser irradiation timing time from the laser oscillator 41 in the laser processing apparatus 40. In other words, after the control unit 43 outputs the timing signal of the galvano scanner 54 to the first galvano drive system 44 and the second galvano drive system 46, the galvano scanner 54 moves the machining position, and the accurate A control signal is output to the amplifier 42 so that the laser beam is emitted from the laser oscillator 41 after waiting for the settling time.
[0062]
Accordingly, it is possible to provide a laser processing apparatus that can automatically perform parameter correction without human intervention, and that can improve productivity associated with improvement in speed and operability. The threshold A2 is preferably set to about 10 μm.
[0063]
As described above, highly accurate correction can be performed by the laser processing apparatus of the present invention, and highly accurate laser processing can be realized. In addition, by setting the number of correction repetitions in the control unit or the like in advance, it is possible to limit the time required for a certain correction process. It is preferable to adjust the processing accuracy according to the correction time, processing quality, and the like.
[0064]
As described above, according to the present invention, in consideration of the settling time of the galvano scanner, the irradiation timing time is set so that the laser light is emitted from the laser oscillator, and automatic correction is performed, so that there is no human intervention. Therefore, it is possible to improve the positioning accuracy and to process the processing object with high accuracy.
[0065]
Further, by correcting optical system distortion, it is possible to perform correction with higher accuracy. Furthermore, by performing the correction process repeatedly based on a predetermined threshold value, more accurate correction can be performed, and stability can be further improved.
[0066]
It should be noted that the present invention is not limited to the specifically disclosed embodiments, and various modifications and embodiments can be considered without departing from the scope of the claimed invention.
[0067]
【The invention's effect】
As described above, according to the present invention, it is possible to improve the positioning accuracy and to process a workpiece with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a conventional laser processing apparatus including a galvano scanner.
2 is a diagram illustrating an example of a correction process in the laser processing apparatus of FIG. 1; FIG.
FIG. 3 is a diagram illustrating an example of an optical system distortion that occurs during conventional laser processing.
FIG. 4 is a diagram illustrating an example of an overshoot in position movement.
FIG. 5 is a diagram showing a first embodiment of a laser processing apparatus according to the present invention.
FIG. 6 is a flowchart of an example showing a flow of correction processing in the present invention.
[Explanation of symbols]
10, 40 Laser processing apparatus 11, 41 Laser oscillator 12, 42 Amplifier 13, 43 Control unit 14, 44 First galvano drive system 15, 45 First carbano mirror 16, 46 Second galvano drive system 17, 47 Second Carbanomirrors 18 and 48 fθ lens 19 and 53 Processing object 20 and 54 Galvano scanner 49 Processing stage 50 CCD camera 51 Error measurement unit 52 Correction unit

Claims (6)

In a laser processing method for correcting an irradiation position where a laser beam emitted from a laser oscillator is irradiated onto a processing object via a galvano scanner and an fθ lens,
An irradiation step of irradiating the laser beam to a plurality of reference irradiation positions;
An error measurement step of measuring an error between a plurality of irradiation points obtained by the irradiation step and the reference irradiation position;
And a correction step of correcting the emission timing of the laser beam emitted from the laser oscillator based on the error obtained in the error measurement step. The correction step includes
The laser processing method according to claim 1, wherein an optical system distortion is corrected before the laser light emission timing is corrected. The irradiation step, the error measurement step, and the correction step include
3. The laser processing method according to claim 1, wherein the laser processing method is repeatedly performed until an error between the plurality of irradiation points obtained in the error measurement step and the reference irradiation position becomes a predetermined threshold value or less. In a laser processing apparatus that corrects an irradiation position in which a laser beam emitted from a laser oscillator is irradiated onto a workpiece via a galvano scanner and an fθ lens,
An irradiation unit that irradiates the laser beam to a plurality of reference irradiation positions;
An error measurement unit that measures an error between a plurality of irradiation points obtained by the irradiation unit and the reference irradiation position;
A laser processing apparatus comprising: a correction unit that corrects the emission timing of the laser beam emitted from the laser oscillator based on an error obtained by the error measurement unit. The correction unit is
The laser processing apparatus according to claim 4, wherein the optical system distortion is corrected before the laser beam emission timing is corrected. The irradiation unit, the error measurement unit, and the correction unit are:
6. The laser processing apparatus according to claim 4, wherein the laser processing apparatus is repeatedly performed until an error between the plurality of irradiation points obtained by the error measurement unit and the reference irradiation position becomes a predetermined threshold value or less.

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