JP2002283077A - Laser processing monitoring device, laser processing monitoring method, laser processing device, and laser processing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To monitor the internal state of a processing area of a workpiece at high speed in real time. SOLUTION: In a laser processing monitoring device 2 for monitoring the progress of laser processing performed by irradiating a laser to a workpiece 4, a vibration generating means 6 for generating vibration in the workpiece 4 during laser processing, A vibration measuring means 13 for measuring the vibration of the object 4 and a judging means 14 for judging the progress of laser processing based on the vibration measurement result by the vibration measuring means 13 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing monitoring device for monitoring a processing state during laser processing.
The present invention relates to a laser processing monitoring method, a laser processing apparatus, and a laser processing method.

[0002]

2. Description of the Related Art In laser processing, it is necessary to stably maintain an optimized processing state in order to obtain high processing quality, but the operation has relied on skilled workers. Especially in laser processing of so-called difficult-to-process materials such as materials with high reflectance to laser wavelength and high melting point materials, slight changes in surface state and non-uniformity of the materials affect the processing quality,
It was difficult even for a skilled worker to maintain high processing quality. Therefore, it is necessary to monitor the progress of laser processing in real time and control the laser processing.

Conventionally, as technologies for monitoring the progress of laser processing, image monitoring for processing an image obtained by a CCD, temperature monitoring using an infrared sensor / thermocouple, light monitoring using a photodiode, and the like have been put to practical use. I have.

Image monitoring is a technique in which the appearance and dimensions of a workpiece are monitored during laser processing, and the results of the monitoring are compared with reference appearances and dimensions to judge the quality of the workpieces. This image monitoring can be easily configured using commercially available parts and has an advantage that has been proven in many other fields, but has the disadvantage that it is not suitable for high-speed monitoring with a laser irradiation frequency of several kilo Kz. is there.

[0005] Temperature monitoring is a technique in which heat radiation from a workpiece is sensed during laser processing to monitor the temperature of a processing portion, and the monitoring result is compared with a predetermined temperature to judge the quality. This temperature monitoring has the advantage of being able to know the processing state directly from the temperature information of the processing part and is also suitable for high-speed monitoring,
If detailed two-dimensional and three-dimensional temperature distributions are handled as temperature information, there is a drawback that they are not suitable for high-speed monitoring like the image monitoring described above.

Light monitoring is a technique in which reflected laser light from a workpiece is sensed, and the quality of the surface condition of a processed portion is determined based on the light intensity of the reflected laser light. This optical monitoring has the advantage of being suitable for high-speed monitoring, but has the disadvantage that the material to be processed must be a material having a high reflectivity, so that the material is limited.

As described above, the monitoring technology currently put to practical use is for monitoring the surface state of the laser processing area, and for monitoring the internal state of the processing area, image processing by an X-ray camera is performed. There are systems, etc., but still in the research stage.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a laser processing monitoring apparatus and method capable of performing high-speed real-time monitoring of the internal state of a processing area of a workpiece. It is another object of the present invention to provide a laser processing apparatus and a method using the same.

[0009]

In order to solve the above-mentioned problems, a laser processing monitoring apparatus according to the present invention is a laser processing monitoring apparatus for monitoring the progress of laser processing for irradiating a workpiece with a laser to perform processing. Vibration generating means for generating vibration in the workpiece during laser processing, vibration measuring means for measuring the vibration of the workpiece, and determination of the progress of the laser processing based on the vibration measurement result by the vibration measuring means And means.

[0010] In the laser processing monitoring device, vibration is generated in the workpiece by the vibration generating means during laser processing, the vibration of the workpiece is measured by the vibration measuring means, and the laser processing is advanced based on the vibration measurement result. Determine the situation. For example, the internal state of the workpiece, such as that a hole has penetrated the workpiece, that multiple workpieces have been joined, and which layer has been processed in a workpiece consisting of multiple layers of different materials. Can be monitored in real time at high speed.

It is preferable that the vibration generating means is a pulse laser, and that the workpiece is processed with the pulse laser. By doing so, the processing laser generating means and the vibration generating means can be shared, and it is not necessary to separately provide a new vibration generating means, and the configuration is simplified.

It is preferable that the vibration measuring means irradiates the workpiece with probe light and measures the vibration of the workpiece by Doppler effect of the reflected light of the probe light. By irradiating the vicinity of the processing portion with the probe light, it is possible to eliminate the influence of the change in the surface state during processing on the vibration measurement, and to perform accurate vibration measurement.

It is preferable that the probe light and the laser be condensed on the workpiece by one condensing lens optical system in order to simplify the configuration.

The determining means obtains, for each pulse of the laser pulse, a ratio of a difference between a maximum displacement amount and a minimum displacement amount of the workpiece with respect to a maximum value of the power of the pulse laser. It is preferable to determine the progress of processing. Alternatively, the determination means may determine a frequency characteristic from the vibration measurement result and determine a progress of laser processing based on the frequency characteristic.

It is preferable that the laser processing is a hole processing for making a hole in a workpiece, and the determining means determines completion of the hole processing.

It is preferable that the workpiece is formed by laminating two or more different materials, and that the determination means determines the progress of laser processing for each material.

It is preferable that the laser processing is a bonding processing for bonding two or more workpieces, and the determining means is for determining a bonding state of the two or more workpieces.

In order to solve the above problems, a laser processing monitoring method according to the present invention generates a vibration in a workpiece during laser processing, measures the vibration of the workpiece, and performs laser processing based on the vibration measurement result. It is a measure of progress. Further, the laser processing apparatus according to the present invention includes the laser processing monitoring apparatus, and control means for controlling laser processing of the workpiece based on the progress of the laser processing monitored by the laser processing monitoring apparatus. It is provided. Further, a laser processing method according to the present invention monitors the progress of laser processing by the laser processing monitoring method, and controls laser processing of a workpiece based on the monitored progress of laser processing.

[0019]

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

FIG. 1 shows a laser processing apparatus 1 provided with a laser processing monitoring apparatus 2 according to the present invention. 3 is
X for placing the workpiece 4 and controlling the position of the workpiece 4
The YZ stage. Above the XYZ stage 3, a laser generator 6 for emitting an SHG-YAG laser 5 as a processing laser, and a SHG-YAG laser 5 emitted from the laser generator 6 are placed on the workpiece on the XYZ stage 3. A mirror 7 that reflects light toward the mirror 4 and a condenser lens 8 that collects the SHG-YAG laser 5 reflected by the mirror 7 are provided. The mirror 7 has a dielectric coating that reflects the SHG-YAG laser 5 having a wavelength of 532 nm emitted from a laser generator 6 and transmits the He-Ne laser 11 having a wavelength of 633 nm emitted from a Doppler measuring instrument 13 described later. Is given.

Between the laser generator 6 and the mirror 7, there is provided a beam sampler 9 for branching a part of the SHG-YAG laser 5 emitted from the laser generator 6, and a SHG branched by the beam sampler 9. A photosensor 10 for measuring the power of the YAG laser 5 is provided. Above the mirror 7, He-Ne is used as an optical probe.
A Doppler meter 13 that emits a laser 11 and irradiates the workpiece 4 via an optical system 12, a mirror 7 and a condenser lens 8 to measure the vibration of the workpiece 4 is arranged. The optical system 12 has a zoom mechanism (not shown) for adjusting the focal position of the He-Ne laser 11 emitted from the Doppler meter 13. Doppler meter 1
3 is He-N emitted from the Doppler meter 13
Angle adjusting mechanism 14 for adjusting the angle of the optical axis of e-laser 11
have.

The laser generator 6, the beam sampler 9, the photo sensor 10, the Doppler meter 13, the optical system 12, and the data processor 15 constitute the laser processing monitoring device 2 of the present invention. The laser generator 6 is a means for emitting a processing laser beam to the workpiece 4 and also a vibration generating means according to the present invention for generating vibrations on the workpiece 4. Doppler meter 13
Constitutes a vibration measuring means of the workpiece 4. The data processor 15 is provided with a SHG-
The determination means of the present invention for determining the progress of the workpiece 4 based on the power of the YAG laser 5 and the vibration of the workpiece 4 measured by the Doppler meter 13 is configured.
Further, the laser generator 6 controls the laser processing by controlling the laser processing by stopping the laser emission by the laser generator 6 based on the progress of the workpiece 4 determined by the data processor 15. An apparatus 6a is provided.

The position where the vibration of the workpiece 4 is measured by the Doppler meter 13 is around the laser processing part.
In the laser processing part, the surface shape is greatly changed by the processing, and even if the He-Ne laser 11 is irradiated from the Doppler measuring device 13 here, the reflected light intensity of the He-Ne laser 11 strongly affects the surface shape. This is because the vibration of the workpiece 4 cannot be measured accurately. Further, in the laser hole processing, as shown in FIG. 2, depending on the processing conditions, a dross 17 is present around the processing hole 16, and the reflected light of the He-Ne laser 11 is scattered by the dross 17, so that an accurate Vibration measurement cannot be performed. On the other hand, at a position far from the laser processing part, the magnitude of the vibration is attenuated by the square of the distance. Therefore, if the distance from the processing part is too large, it becomes difficult to measure the vibration of the workpiece 4. Therefore, He-Ne
The spot of the optical probe of the laser 11 has to be adjusted to a position where the surface shape of the workpiece 4 does not change and does not overlap the dross 17 and is as close as possible to the processing portion. In the embodiment, 99.times.
When a hole having a diameter of 50 μm was formed in a 99% pure copper plate, the vibration of the workpiece 4 could be measured at a position 10 mm from the center of the laser processing portion.

The position for measuring the vibration of the workpiece 4 is adjusted by the zoom mechanism of the optical system 12 and the angle adjusting mechanism 14 of the Doppler meter 13. Specifically, first,
The position of the workpiece 4 is adjusted by the XYZ stage 3 so that processing can be performed at the focal position of the processing laser of the SHG-YAG laser 5. Next, the spot of the optical probe of the He-Ne laser 11 on the workpiece 4 is separated from the spot of the processing laser of the SHG-YAG laser 5 by the angle adjusting mechanism 14 of the Doppler measuring meter 13 by a distance that allows vibration measurement. To move. The focal point is adjusted by the zoom mechanism of the optical system 12 so that the amount of laser light returning to the Doppler meter 13 is maximized, and the optical system 12 is fixed.

As described above, the laser generator 6 is not only a processing laser generating means but also a vibration generating means. The principle of vibration generation by the laser generator 6 will be described. As shown in FIG. 3, when the SHG-YAG laser 5 is irradiated, the workpiece 4 in the processing area evaporates to generate steam S. As a reaction of the evaporation S, reverse braking radiation f is applied to the workpiece 4. As a result, vibration occurs in the workpiece 4.
When the drilling of the workpiece 4 is completed and the through-hole 18 is formed in the workpiece 4, the SHG-YAG laser 5 passes through the through-hole 18. As a result that no steam S is generated and no reverse bremsstrahlung f is received,
Vibration disappears. As described above, the vibration occurs during the laser processing, and the vibration disappears when the processing is completed. Therefore, by measuring the vibration of the workpiece 4 by the Doppler meter 13 during the processing, the progress of the processing, that is, the processing progresses. It is possible to monitor whether the operation is in progress, whether the operation is completed, and the like.

The SHG-YAG laser 5 as a processing laser emitted from the laser generator 6 is a pulse laser, and the laser irradiation time is as short as several hundred ns.
On the other hand, the time for measuring the vibration by the Doppler meter 13 is on the order of several hundred μs to ms. Therefore, when the SHG-YAG laser 5 is regarded as the excitation source of the workpiece 4, the Doppler measurement meter 13 measures the transient response of the impulse of the workpiece 4, and the natural frequency can be obtained. it can.

Next, the laser processing monitoring operation by the data processor 15 will be described. Each laser pulse of the SHG-YAG laser 5 emitted from the laser generator 6 is branched by 1% by the beam sampler 9, and The power is measured by the photo sensor 10. As a result, FIG.
A temporal change in the power of the laser pulse of the SHG-YAG laser 5 as shown in FIG. On the other hand, the workpiece 4 is irradiated with an optical probe of the He-Ne laser 11 by the Doppler meter 13, and the vibration of the workpiece 4 is measured from the power of the reflected light. As a result, a temporal change in the displacement of the workpiece 4 as shown in FIG. Next, the difference between the maximum value P of the laser pulse power of the SHG-YAG laser 5 shown in FIG. 4B and the maximum value and the minimum value of the displacement of the workpiece 4 shown in FIG. Ami
n), that is, the absolute displacement amount is obtained. Then, the ratio (Amax-Ami) of the absolute displacement amount (Amax-Amin) of the workpiece 4 to the maximum value P of the power of each laser pulse.
n) / P can be determined and the progress of laser processing can be monitored based on this ratio. For example, in the case of laser drilling, when the ratio is higher than a certain threshold value as shown at point P1 in FIG. 4A, laser processing is in progress, and as shown at point P2 in FIG. When the value becomes equal to or less than a certain threshold value, it is determined that the hole machining is completed. Based on this determination result, the control device 6a stops the laser emission by the laser generator 6, and ends the laser processing.

In the above embodiment, monitoring of laser hole processing has been described. However, the laser processing monitoring device according to the present invention can also monitor other laser processing as described below.

FIG. 5 shows laser drilling of a workpiece having a structure in which two or more different materials are laminated. The workpiece includes a first layer 21 of copper having a thickness of 10 μm, a second layer 22 of polyimide having a thickness of 80 μm, and a third layer 2 of copper having a thickness of 10 μm.
3 is a hybrid substrate 24 having a total thickness of 100 μm and a three-layer structure. In the laser hole processing of the hybrid substrate 24 having such a three-layer structure, the processing rate differs for each layer, and the ratio (Amax−Amin) / P of the absolute displacement amount of the workpiece to the maximum value of the power of each laser pulse is determined for each layer. Therefore, the completion of laser processing inside the hybrid substrate 24, that is, for each layer, can be monitored. Therefore, as shown in FIG. 5A, if the laser processing is stopped when the hole processing of the first layer 21 is completed, the holes can be formed only in the first layer 21.

FIG. 6 shows a laser micro welding process for joining two or more workpieces. In this processing, a wire 27 having a diameter of 50 μm is welded to a land 26 having a diameter of 400 μm on the printed board 25. A pulse YAG laser is used as a processing laser, a displacement of the wire 27 is measured by a Doppler meter, and a frequency characteristic is obtained by FFT. The displacement of the wire 27 after the wire 27 is joined to the land 26 as shown in FIG. 6B is greater than that before the wire 27 is joined to the land 26 as shown in FIG. And a large change is obtained in the frequency characteristic. Therefore, from the change in the frequency characteristic of the wire 27, it is possible to monitor the time of joining the wire 27 to the land 26. If laser emission is stopped at this point, welding can be performed efficiently.

Similarly, as shown in FIG.
Also in the joining process of overlapping the spots 8 and 29, it is possible to monitor the time of joining of the two sheet materials 28 and 29 from the change in the frequency characteristic of the upper sheet material 28. If the laser emission is stopped at this time, The joining process can be performed efficiently.

[0032]

As is apparent from the above description, according to the present invention, vibration is generated in a workpiece during laser processing, and the progress of laser processing is determined based on the vibration measurement result of the workpiece. So that the hole has penetrated the workpiece,
It is possible to perform high-speed real-time monitoring of the internal state of a workpiece, such as the fact that a plurality of workpieces have been joined and the processing of which layer has been completed in a workpiece made of a plurality of layers made of different materials.

[Brief description of the drawings]

FIG. 1 is a schematic view of a laser processing apparatus provided with a laser processing monitoring apparatus according to the present invention.

FIG. 2 is a plan view of a workpiece showing a dross around a processing hole.

FIGS. 3A and 3B show laser hole processing, and FIG.
(B) is sectional drawing which shows the time of completion.

FIG. 4 (a) is a temporal change in displacement of a workpiece,
(B) is a graph showing a temporal change of the power of the processing pulse.

5A and 5B are cross-sectional views showing laser hole processing of a multi-layer substrate, in which FIG. 5A shows a state when processing of a first layer is completed and FIG.

FIG. 6 shows a laser joining process between a substrate and a wire,
(A) is a front view showing before joining, (b) is showing after joining.

FIG. 7 shows a laser joining process of two plate materials,
(A) is sectional drawing which shows before joining, (b) shows after joining.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Laser processing monitoring apparatus 4 Workpiece 5 SHG-YAG laser (processing laser) 6 Laser generator (vibration generating means) 6a Controller 8 Condensing lens 11 He-Ne laser (optical probe) 13 Doppler measurement Meter (vibration measurement means) 14 Data processor (judgment means)

Claims (15)

[Claims] 1. A laser processing monitoring apparatus for monitoring the progress of laser processing in which a workpiece is irradiated with a laser to monitor the progress of the laser processing, comprising: a vibration generating means for generating vibration in the workpiece during laser processing; A laser processing monitoring apparatus comprising: a vibration measuring means for measuring vibration; and a judging means for judging a progress of laser processing based on a result of the vibration measurement by the vibration measuring means. 2. The laser monitoring apparatus according to claim 1, wherein said vibration generating means is a pulse laser, and said workpiece is processed by said pulse laser. 3. The apparatus according to claim 1, wherein the vibration measuring means irradiates the workpiece with probe light and measures the vibration of the workpiece by Doppler effect of reflected light of the probe light. 3. The laser processing monitoring device according to 2. 4. The laser processing monitoring apparatus according to claim 3, wherein the probe light is applied to a vicinity of a processing part. 5. The laser processing monitoring apparatus according to claim 3, wherein the probe light and the laser are condensed on a workpiece by one condensing lens optical system. 6. The determination means obtains, for each pulse of the laser pulse, a ratio of a difference between a maximum displacement amount and a minimum displacement amount of the workpiece with respect to a maximum value of the power of the pulse laser,
7. The laser processing monitoring device according to claim 2, wherein a progress of laser processing is determined based on the change in the ratio. 7. The method according to claim 2, wherein the determining means determines a frequency characteristic from the vibration measurement result and determines a progress of laser processing based on the frequency characteristic. The laser processing monitoring device as described in the above. 8. The laser processing according to claim 1, wherein the laser processing is a hole processing for making a hole in a workpiece, and the determination unit determines completion of the hole processing. Laser processing monitoring equipment. 9. The apparatus according to claim 1, wherein the workpiece is formed by laminating two or more different materials, and wherein the determining means determines the progress of laser processing for each material. 9. The laser processing monitoring device according to any one of items 1 to 8. 10. The method according to claim 1, wherein the laser processing is a bonding processing for bonding two or more workpieces, and the determining unit determines a bonding state of the two or more workpieces. 9. The laser processing monitoring device according to any one of 8. 11. A method for monitoring the progress of laser processing in which a workpiece is irradiated with a laser to monitor the processing, comprising: generating a vibration in the workpiece during laser processing; measuring the vibration of the workpiece; A laser processing monitoring method comprising: determining a progress of laser processing based on a measurement result. 12. A ratio of a difference between a maximum displacement amount and a minimum displacement amount of a workpiece to a maximum value of the power of the laser from a vibration measurement result, and a progress of laser processing is determined based on the change in the ratio. The laser processing monitoring method according to claim 11, wherein 13. The laser processing monitoring method according to claim 11, wherein a frequency characteristic is obtained from the vibration measurement result, and a progress of laser processing is determined based on the frequency characteristic. 14. A laser processing monitoring apparatus according to any one of claims 1 to 10, and control for controlling laser processing of a workpiece based on the progress of the laser processing monitored by the laser processing monitoring apparatus. And a laser processing device. 15. The progress of laser processing is monitored by the laser processing monitoring method according to claim 11, and the laser processing of the workpiece is controlled based on the monitored progress of laser processing. A laser processing method.