JP2001300755A - Method and device for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method of laser beam machining and a device for laser beam machining by which a precise machining is performed without generating a deviation in a machining position due to an error of the positioning. SOLUTION: A machining pattern whose reflectivity is different from that of other parts is formed on a work 1 for the laser beam machining. A galovanoscanner scans an optical axis for machining, then the surface of the work 1 is scanned with a detected light from a detector 8 which passes through a laser oscillator 3, a dichroic mirror 93, galvanomirrors 42 and 43, and a lens 5. The detected light reflected on the surface of the work 1 is image-formed on a photosensor 92 via the lens 5, the galvanomirrors 42 and 43, the dichroic mirror 93, and a focusing lens 91. The output from the photosensor 92 becomes larger on the machining pattern and smaller on other parts, the detected signal of the photosensor 92 is binarized by a threshold value preliminarily set on a comparator of a triggering means 10 and is inputted to the laser oscillator 3 after giving a delay time of a predetermined time td.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and apparatus for performing fine processing at high speed using a galvanometer mirror for transmitting a laser beam.

[0002]

2. Description of the Related Art A processing apparatus and a processing method using a galvanometer mirror for transmitting a laser beam in the prior art are shown in FIG.
This will be described with reference to FIG.

FIG. 7 shows a conventional laser processing apparatus.
As shown in FIG. 1, a laser oscillator 3 having a laser head 31 and a laser power supply 32, a galvano controller 41, an X-axis galvanometer mirror 42, a Y-axis galvanometer mirror 43, and a condenser lens for condensing a laser beam 5 is provided.

Then, a galvano controller 41 and X
A galvanometer scanner 4 is composed of the axis galvanometer mirror 42 and the Y-axis galvanometer mirror 43. The galvanometer scanner 4 transmits the laser beam output from the laser oscillator 3 and scans in the XY directions.

When used on a production line or the like, a transfer device 6 for supplying and recovering the work 1 and a jig 7 for fixing the work 1 are added to the laser processing device.

[0006]

After a pattern having a certain function, such as a printed circuit board or a silicon wafer, is already formed using the above-mentioned laser processing apparatus, a very large number of fine patterns are formed in accordance with the pattern. A description will be given of an example of a case in which a hole is drilled.

FIG. 8 is a top view of the work 1 on which the wiring patterns 2 and the like have already been formed. As a procedure for drilling a large number of positions irregularly arranged along the wiring pattern 2 by a laser processing apparatus, a program is created in which coordinates of the irregularly arranged processing positions are sequentially designated,
For example, the laser is irradiated at the first drilling position A, the laser irradiation position is moved to the next drilling position B by the galvano scanner 4, and the laser is irradiated there.

In this manner, a predetermined number of holes are drilled by repeating the movement to the coordinates created by the program and the laser irradiation.

The work 1 is performed by using the above-described processing procedure.
In the case where holes are drilled by supplying and fixing to the fixing jig 7 by the transport device 6, the following positioning error occurs.

(1) If the work 1 has a round hole as a reference for positioning (for example, four corners of the work 1), the transfer device 6
Is supplied to the fixing jig 7 from above, a pin on the fixing jig 7 is fitted and inserted into a positioning round hole formed in the work 1. At this time, since a gap is set between the positioning round hole and the pin on the fixing jig 7, the gap is set to 1
A positioning error of about 0 μm or more occurs.

(2) An error between arbitrary drilling positions occurs due to a mechanical manufacturing error when forming the wiring pattern 2 with respect to the reference position of the work 1 and a manufacturing error in the wiring pattern 2.

(3) The galvano scanner 4 is an open control for performing positioning by instructing a voltage corresponding to the position,
Further, the position gain with respect to the zero point and the voltage changes under the influence of the temperature, so that a positioning error occurs. For example, when the processing range is several tens of mm, a positioning error of 10 to 20 μm occurs.

When the positioning errors as described above accumulate, the processing position shifts from a predetermined position, does not match the position of the wiring pattern 2, and deviates from the original target position.
For example, in the case where the wiring boards are vertically stacked to form a through hole for conducting the upper and lower wiring patterns 2, if the processed position is shifted from the wiring pattern 2, conduction cannot be achieved.

The hole diameter that can be obtained by laser processing is several tens μm.
When forming a high-density wiring pattern as small as the m level and according to the processing diameter, if a positioning error of several tens of μm occurs due to the accumulated error as described above, the adjacent wiring pattern 2 may be damaged.

For this reason, as a method of correcting an error of a processing position in laser processing, for example, Japanese Patent Laid-Open No. 10-1
There is a technique described in Japanese Patent No. 50279.

In the technique described in Japanese Patent Application Laid-Open No. H10-150279, target marks are formed at four corners of a substrate, and the target marks are measured with a CCD camera to measure the position of the substrate. And correcting the displacement of the substrate position from the actually measured values to generate drive data for the galvano head and the XY table.

However, Japanese Patent Application Laid-Open No. 10-1502
In the technique described in Japanese Patent Application Publication No. 79-79, the work 1 described in (1)
Can be corrected, but the error of the wiring pattern in (2) and the error of the galvano scanner 4 in (3) cannot be corrected.

Another method is disclosed in Japanese Patent Laid-Open No. 2-442.
There is a technique described in Japanese Patent Publication No. This Japanese Patent Laid-Open No. 2-4
The technology described in Japanese Patent No. 4201 captures a position shift of an irradiation target on a moving stage reflected by a condenser lens, a galvanometer mirror, and a dichroic mirror by a CCD camera, and outputs data as an image output. And
Based on the data, the control section coarsely controls the moving amount of the moving stage, performs a correcting operation of the galvanomirror, and performs a correcting operation for correcting the positional deviation.

However, according to the technique described in Japanese Patent Application Laid-Open No. 2-44201, time is required for image processing and position correction at each of a large number of processing positions, and the productivity is reduced.

In addition, since the movement before the image processing includes all of the above-mentioned errors (1) to (3), when the processing positions are close to each other, another processing position is set as a target processing position. In some cases, a misperception occurs, and in this case, the correction does not make sense.

An object of the present invention is to realize a laser processing method and a laser processing apparatus capable of performing high-precision processing without causing a processing position shift due to a positioning error.

[0022]

In order to achieve the above object, the present invention is configured as follows. (1) In a laser processing method in which a laser oscillated by a laser oscillator is guided to a workpiece by a processing optical system having a galvanomirror, and the workpiece is laser-processed, a laser is placed at a scheduled laser processing position of the workpiece. The processing optical system forms a processing pattern with a different reflectance from that of the other parts, and the processing optical system scans the irradiation axis of the processing laser within the processing range of the workpiece. The detection light is irradiated to the surface of the workpiece, the reflected light of the detection light from the surface of the workpiece is detected, and the position where the reflectance of the detection light of the workpiece changes is detected. The workpiece is irradiated with a processing laser based on the processing.

(2) Preferably, in the above (1),
The center point of the processing pattern substantially coincides with the center point of the laser processing scheduled position.

(3) Preferably, in the above (2), the shape of the processing pattern is a rhombus.

(4) a laser oscillator for oscillating a laser;
A laser processing device equipped with a processing optical system having a galvanometer mirror for guiding the laser to the workpiece and positioning the laser irradiation on the workpiece at high speed. A detection light source that generates the detection light to be irradiated; a reflection light detection unit that detects reflection light of the detection light from the workpiece and generates a detection signal corresponding to the detected reflection light; A trigger means for irradiating the workpiece with a processing laser; and a control means for changing a scanning range and a scanning pitch when scanning the laser irradiation range by the galvanomirror. A processing pattern having a laser reflectance different from that of the other portions is formed at the planned processing position.

(5) Preferably, in the above (4),
When the duration of the reflected light from the workpiece becomes equal to or longer than a predetermined time, the apparatus further includes a determination unit that supplies a laser irradiation start signal to the laser oscillator.

In the present invention configured as described above,
The scanning range and the scanning pitch are determined by the control unit, and the laser irradiation range is scanned by the galvanomirror. At that time, the detection unit irradiates the workpiece with detection light coaxially with the processing laser, and detects the detection light. The reflected light from the surface of the workpiece is detected, and the processing position of the workpiece is detected.

Based on the processing position of the workpiece, a predetermined delay time is given by the trigger means to send a trigger signal to the laser oscillator to irradiate the laser.

Thus, closed loop control based on the processing position of the workpiece can be performed, and highly accurate positioning processing can be performed.

Further, the processing position pattern is, for example, a rhombus, and a signal is sent to the trigger means when the duration of the reflected light from the workpiece of the detection light source exceeds a certain time. Reduced laser processing can be performed.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing method and a laser processing apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is a schematic configuration diagram of a laser processing apparatus according to a first embodiment of the present invention. In FIG. 1, a laser processing apparatus includes a laser oscillator 3 having a laser head 31 and a laser power supply 32, and a galvano controller 41.
, X-axis galvanometer mirror 42 and Y-axis galvanometer mirror 4
3, a condensing lens 5 for condensing a laser beam, a detection light source 8 for detecting light emitted to the workpiece coaxially with the processing laser, and a detection light amount by receiving the detection light from the detection light source 8. Detecting means 9 for outputting a signal corresponding to
And a control means 11 for outputting a trigger signal to the laser oscillator 3 based on a signal from the laser oscillator 3.

The galvano controller 41, the X-axis galvanometer mirror 42, and the Y-axis galvanometer mirror 43 constitute a galvanometer scanner (processing optical system) 4. The galvanometer scanner 4 outputs a laser beam emitted from the laser oscillator 3. Is transmitted (guided), and the surface of the work (workpiece) is X
Scan in the Y direction.

The control means 11 designates a scanning range, a scanning pitch and the like of the galvano scanner 4.

The detecting means 9 includes an imaging lens 91,
A photosensor 92 and a dichroic mirror 93 are provided. The detection light reflected on the surface of the work 1 is imaged on the photosensor 92 by the imaging lens 91 via the galvanometer mirrors 43 and 42 and the dichroic mirror 93.

As shown in FIG. 2, the trigger means 10 includes a comparator 101 to which a detection signal from the photo sensor 92 of the detection means 9 is supplied, and a delay circuit 102. The output signal from the delay circuit 102 is It is supplied to a laser power supply 32.

Next, the operation of the laser processing apparatus having the above configuration will be described. The work 1 is supplied from the transfer device 6 to the fixing jig 7, and the work 1 is fixed on the fixing jig 7.

As shown in FIG. 3, the galvano scanner 4 is controlled on the workpiece 1 fixed on the fixing jig 7 in accordance with a scanning range and a scanning pitch set in advance by the control means 11.

At this time, at the same time as the formation of the pattern 2 for performing a certain function, the processing pattern 2A having a different reflectance from the other portions is formed on the work 1 for laser processing. Here, a case where the reflectance of a portion indicating the processing position of the pattern 2A for laser processing is high will be described as an example.

When the optical axis for processing is scanned by the galvano scanner 4 as described above, the detection light from the detection light source 8 that is continuously output also includes the laser oscillator 3, the dichroic mirror 93, and the galvanometer mirrors 42 and 43. , Through the lens 5, and similarly scanned on the surface of the work 1.

The detection light applied to the surface of the work 1 is reflected on the surface of the work 1, and the reflected light passes through the lens 5,
The light is reflected by the galvanometer mirrors 42 and 43, reflected by the dichroic mirror 93, and is imaged on the photosensor 92 by the imaging lens 91.

FIG. 4 shows processing patterns 2 having different reflectivities.
6 is a time chart of signals from detection to laser irradiation when scanning where A is formed.

In FIG. 4, when the galvanomirror 42 is operated from the starting point O of a certain scanning line to the ending point E of the scanning line, the signal detected by the detecting means 9 is detected by the photo sensor 92 in the processing pattern 2A having a high reflectance. In a portion where the output is large and the reflectance is small, the output is small, and changes as shown in FIG.

The detection signal of the photo sensor 92 is binarized at a threshold level (threshold) set in advance by the comparator 101 of the trigger means 10 and binarized as shown in FIG. Rectangular signal,
A delay time is given by a predetermined time td by the delay circuit 102, and a signal as shown in FIG. 4C is input to the laser oscillator 3.

The laser oscillator 3 irradiates a laser at the timing shown in FIG. 4D with the signal shown in FIG. 4C as a trigger. Here, the delay time td
Is used to adjust the distance from an edge position having a different reflectance to a position to be actually processed.

As described above, since the laser is irradiated in accordance with the position of the processing pattern 2 A having a high reflectance for laser processing formed in advance on the work 1, the laser beam is emitted when the workpiece is fixed to the fixing jig 7 from the transfer device 6. The error, the position error in the work 1, for example, in the wiring pattern, and the positioning error of the galvano scanner are cancelled, so that accurate processing can be performed.

Further, in the case of this laser processing method, it is a waste time to scan a place where there is no processing position.
As shown in (1), if the scanning range is set near the processing position and is registered in the control means 11, the processing efficiency is dramatically improved.

Even in this case, the processing operation is simpler than in the method of finely specifying all the processing positions, since it is only necessary to roughly set the range specification.

Also, in the first embodiment described above, the processing pattern 2A having a large reflectance of the processing portion is shown. Conversely, even when the reflectance of the processing portion is low, the processing can be performed with high accuracy by the same method. can do.

As described above, according to the first embodiment of the present invention, the processing pattern 2A having a reflectance different from that of the other portions is formed at the processing target position of the processing object, and the processing pattern 2A is formed. By irradiating the object to be processed with the same path as the path where the laser is irradiated to the object to be processed, and detecting the reflected light, the position of the pattern 2A is detected, and the processing laser light is applied to the position. Since irradiation is performed, it is possible to realize a laser processing method and a laser processing apparatus capable of performing high-precision processing without causing a processing position shift due to a positioning error.

FIG. 5 is a schematic configuration diagram of a laser processing apparatus according to a second embodiment of the present invention. In the example of FIG. 5, the trigger signal (laser irradiation start signal) to the laser oscillator 3 is controlled by the duration of the reflected light from the work 1 of the detection light source 8 in the configuration of the laser processing apparatus shown in FIG. This is an example of a laser processing apparatus in which the means 12 is added between the trigger means 10 and the laser power supply 32.

A time chart of signals when the reflectivity of the portion to be processed is increased using the laser processing apparatus having the configuration shown in FIG. 5 as in FIG. 4 will be described with reference to FIG. In addition,
In the case of the example shown in FIG. 5, while reducing the scanning pitch,
The portions of the processing pattern 2A having different reflectivities are rhombic.

Also, as the scanning pitch becomes smaller, the scanning lines by the galvano scanner are divided into a line from the start point O1 to the end point E1, a line from the start point O2 to the end point E2, and a line from the start point O3 to the end point E3. 3
The case where the line passes through the processing section will be described as an example.

Although the scanning method can be performed in a shorter time by sequentially repeating the forward and reverse directions, all the three lines have the same direction for the purpose of explaining the time chart.

The output from the photo sensor 92 in the first line when scanning as described above is performed by the processing pattern 2A.
As shown in FIG. 6A, the time of the portion where the reflected light is large, that is, the portion where the output of the photo sensor 92 is large, is short.

Here, the discriminating means 12 is shown in FIG.
As shown in (C), the comparator 1 of the trigger means 10
A gate signal is generated after a certain time t0 from the rising of the output signal of 00. Then, only when the AND condition between the gate signal and the output signal of the comparator 100 is satisfied, the determination means 12 validates the trigger signal transmitted to the laser oscillator 3.

In the case of the first line in FIG. 6, since the duration of the portion where the reflected light is large is short, the output signal from the comparator 100 is immediately turned off, and the AND condition with the gate signal is not satisfied. Therefore, no trigger signal is output.

Next, in the case of the second line, since it passes through the central portion of the processing pattern 2A, FIG.
As shown in (E), the input signal from the photosensor 92 and the output signal from the comparator 100 have a long duration.

Therefore, as shown in FIGS. 6E and 6F, the AND condition between the output signal from the comparator 100 and the gate signal is satisfied, and as shown in FIGS. 6G and 6H. Then, a trigger signal is output from the trigger means 10 to the laser power supply 32, and the laser is irradiated.

In the case of the scanning of the third line, since the detection signal has already scanned the portion processed by the laser, the reflected light from the work 1 is small, and the duration of the output signal of the comparator 100 becomes short. , No trigger signal is output.

As described above, for example, when the processing position is designated by the diamond-shaped processing pattern 2A having a reflectance different from that of the other portions, the laser beam is more centrally located at the processing expected position by judging the duration of the reflected light. Is irradiated, so that the accuracy of the processing position can be improved.

As described above, according to the second embodiment of the present invention, the same effects as those of the first embodiment can be obtained, and a laser processing method and a laser processing apparatus with further improved processing accuracy. Can be realized.

In the above example, the shape of the processing pattern 2A is a rhombus, but the shape is not limited to the rhombus, and the center point of the processing pattern 2A is substantially equal to the center point of the laser processing scheduled position. The sides of the circle, oval, square, cross, and quadrilateral that match and are bulged at the center of the planned processing position compared to the end are arc-shaped (each side is convex toward the center. (Preferably) can contribute to the improvement of processing accuracy.

The object to be processed by the laser processing method of the present invention includes, in addition to a printed circuit board, a multi-layer substrate and a silicon wafer, those which require formation of liquid crystal and the like and through holes.

In order to form a processing pattern 2A having a reflectance different from that of the other portions at the processing target position of the processing object, for example, silicon nitride or silicon carbide is placed at the processing target position.
What is necessary is just to apply the rhombic shape as described above.

In the above-described example, the processing pattern 2A is formed at the same time as the formation of the wiring pattern 2 and the like. However, the processing pattern 2A is formed in a different process from that of the wiring pattern and the like. It is also possible.

[0067]

According to the present invention, a processing pattern having a reflectivity different from that of other parts is formed at a processing target position of a processing object, and a processing laser beam is irradiated onto the processing object. By irradiating the object to be processed along the same path as above and detecting the reflected light thereof, the position of the pattern is detected, and the position is irradiated with the processing laser light. A laser processing method and a laser processing apparatus capable of performing high-precision processing without causing a shift in a processing position can be realized.

Therefore, it is possible to perform high-precision positioning processing in which a deviation in workpiece positioning due to a dimensional error of the workpiece during processing, a positioning error by the moving means of the workpiece, a positioning error when supplying the workpiece by the transfer device or the like is suppressed. Become.

Also, by simply specifying a simple scanning range,
Since the processing position is detected and the processing is performed automatically, as the number increases, the troublesome work of specifying the processing position is released.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a trigger unit according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a processing locus according to the first embodiment of the present invention.

FIG. 4 is a time chart of one cycle of laser processing according to the first embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a laser processing apparatus according to a second embodiment of the present invention.

FIG. 6 is a time chart of one cycle of laser processing according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a laser processing apparatus according to the related art.

FIG. 8 is an explanatory diagram of a work processing unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Work 2 Wiring pattern 2A Processing pattern 3 Laser oscillator 4 Galvano scanner 5 Condensing lens 6 Conveying device 7 Fixing jig 8 Detection light source 9 Detection means 10 Trigger means 11 Control means 12 Discrimination means 31 Laser head 32 Laser power supply 41 Galvano controller 42, 43 Galvano mirror 91 Imaging lens 92 Photosensor 93 Dichroic mirror 101 Comparator 102 Delay circuit

Claims (5)

[Claims] 1. A laser oscillated by a laser oscillator,
In a laser processing method of guiding a workpiece by a processing optical system having a galvanomirror and performing laser processing on the workpiece, the laser processing is performed at a position where the laser processing of the workpiece is different from that of other parts. A pattern is formed, and the processing optical system scans the irradiation axis of the processing laser within the processing range of the workpiece, and irradiates the surface of the workpiece with detection light coaxially with the processing laser light. Detecting the reflected light from the surface of the workpiece to detect the position where the reflectance of the detected light of the workpiece changes, and irradiating the processing laser to the workpiece based on the change position of the reflectance. A laser processing method. 2. The laser processing method according to claim 1, wherein
A laser processing method, wherein a center point of the processing pattern substantially coincides with a center point of the laser processing scheduled position. 3. The laser processing method according to claim 2, wherein
The laser processing method, wherein the shape of the processing pattern is a rhombus. 4. A laser processing apparatus comprising: a laser oscillator for oscillating a laser; and a processing optical system having a galvanomirror for guiding the laser to a workpiece and positioning the laser irradiation on the workpiece at high speed. In the apparatus, a detection light source that generates detection light irradiated on the workpiece coaxially with the processing laser, detects reflected light of the detection light from the workpiece, and outputs a detection signal corresponding to the detected reflected light. Reflected light detecting means to be generated; trigger means for irradiating a workpiece with a processing laser based on the detection signal; and a scanning range and a scanning pitch for scanning a laser irradiation range by the galvanomirror. A machining pattern having a laser reflectivity different from that of the other portion is formed at a laser processing scheduled position on the workpiece. The processing equipment. 5. The laser processing apparatus according to claim 4, wherein
A laser processing apparatus, further comprising: a determination unit that supplies a laser irradiation start signal to the laser oscillator when a duration of light reflected from a workpiece becomes equal to or longer than a predetermined time.