CN108698165B

CN108698165B - Laser processing apparatus

Info

Publication number: CN108698165B
Application number: CN201780011198.5A
Authority: CN
Inventors: 奥平恭之
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2016-03-09
Filing date: 2017-03-06
Publication date: 2020-06-26
Anticipated expiration: 2037-03-06
Also published as: JP2017159317A; WO2017154800A1; TWI658892B; KR20180122605A; TW201731617A; CN108698165A

Abstract

The invention provides a laser processing apparatus. The acousto-optic deflector diverts the laser beam to any one of a cutoff path, a 1 st processing path, and a 2 nd processing path. The beam deflectors are respectively arranged on the 1 st processing path and the 2 nd processing path. The control device repeatedly performs the following steps: a step of operating the beam deflector, and a step of controlling the acousto-optic deflector so as to cut the laser pulse from the original laser pulse to the 1 st processing path, and then cut the laser pulse to the 2 nd processing path. In the process of repeating this step, the elapsed time from the time when the laser light source is instructed to start oscillation to the time when the laser pulse is cut into the 1 st processing path is constant. Even if the pulse width of the laser pulse to be cut into the 1 st processing path is changed, the elapsed time from the transmission of the cutting signal to the 1 st processing path to the transmission of the cutting signal to the 2 nd processing path to the acousto-optic deflector does not change.

Description

Laser processing apparatus

Technical Field

The present invention relates to a laser processing apparatus that cuts out at least two laser pulses from one laser pulse on a time axis and performs laser processing on at least two axes.

Background

Patent document 1 discloses a laser processing apparatus for performing drilling processing using a laser beam. The laser processing apparatus includes a laser light source and an acousto-optic element (acousto-optic deflector). The acousto-optic element diverts the pulse laser beam output from the laser light source to one of a path toward the beam stop and a 1 st processing path and a 2 nd processing path toward the object to be processed. The pulse laser beam diverted to the 1 st processing path or the 2 nd processing path is deflected by the gaffeno scanner and then enters a target position of the processing object.

The laser beam is diverted to the 1 st processing path during a certain period within the pulse width of one laser pulse, to the 2 nd processing path during another certain period, and to the cutter path during the remaining period. Thus, two laser pulses can be cut out from one laser pulse, and laser processing can be performed on two axes.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-186822

Disclosure of Invention

Technical problem to be solved by the invention

The light intensity of a laser pulse output from a carbon dioxide laser or the like generally decreases with the passage of time from the rise time. When a plurality of laser pulses are cut out from one laser pulse, the light intensity of a laser pulse cut out relatively later in time is weaker than the light intensity of a laser pulse cut out relatively earlier in time. Therefore, it is difficult to equalize the machining quality in each machining axis.

The invention aims to provide a laser processing device which can make processing quality consistent on each processing shaft when laser processing is carried out on a plurality of processing shafts.

Means for solving the technical problem

According to an aspect of the present invention, there is provided a laser processing apparatus including:

a laser light source that outputs a laser beam;

an acousto-optic deflector which is disposed on a path of the laser beam outputted from the laser light source and diverts the incident laser beam to any one of a cut-off path directed to a beam cut-off, a 1 st processing path, and a 2 nd processing path;

a stage configured to hold a processing object at a position where a 1 st laser pulse diverted to the 1 st processing path is incident and at a position where a 2 nd laser pulse diverted to the 2 nd processing path is incident;

a 1 st beam deflector and a 2 nd beam deflector which are respectively arranged on the 1 st processing path and the 2 nd processing path and change an incident position of the object held on the table; and

a control device that controls the laser light source, the acousto-optic deflector, the 1 st beam deflector, and the 2 nd beam deflector,

the control device repeatedly performs the following steps:

moving the incident positions of the 1 st laser pulse and the 2 nd laser pulse to target positions by operating the 1 st beam deflector and the 2 nd beam deflector;

a step of instructing the laser light source to start oscillation;

a step of controlling the acousto-optic deflector so that the 1 st laser pulse is cut out from the original laser pulse output from the laser light source to the 1 st processing path, and then the 2 nd laser pulse is cut out from the same original laser pulse to the 2 nd processing path; and

a step of instructing the laser light source to stop oscillating,

in the course of repeating the steps described above,

an elapsed time from a time point when the laser light source is instructed to start oscillation to a time point when the 1 st laser pulse is cut from the original laser pulse output from the laser light source to the 1 st processing path is constant,

the pulse width of the 1 st laser pulse to be cut into the 1 st processing path is changed, and the elapsed time from the transmission of the cutting signal to cut the 1 st laser pulse into the 1 st processing path to the transmission of the cutting signal to cut the 2 nd laser pulse into the 2 nd processing path to the acousto-optic deflector is not changed.

Effects of the invention

Even if the pulse width of the 1 st laser pulse is changed, the elapsed time from the cutting of the 1 st laser pulse to the cutting of the 2 nd laser pulse is not changed. Therefore, the ratio of the light intensity of the original laser pulse at the cutting timing of the 1 st laser pulse to the light intensity of the original laser pulse at the cutting timing of the 2 nd laser pulse becomes almost constant. Even if the pulse width of the 1 st laser pulse is changed, the light intensity of the 1 st laser pulse and the light intensity of the 2 nd laser pulse can be made almost equal by adjusting the diffraction efficiency to the 1 st processing path and the diffraction efficiency to the 2 nd processing path. As a result, the quality of the processing by the 1 st laser pulse and the processing by the 2 nd laser pulse can be equalized.

Drawings

Fig. 1 is a schematic view of a laser processing apparatus according to an embodiment of the present invention and a reference example.

Fig. 2 (a) is a schematic plan view of a printed wiring board as an example of a processing object, fig. 2 (B) is a partial cross-sectional view of the printed wiring board, and fig. 2 (C) is a cross-sectional view showing a shape of a hole in a hole forming process in a drilling process by irradiation of a pulse laser beam.

Fig. 3 is a partial timing chart of the operation state of the beam deflector, the oscillation command signal, the path selection signal, and the cut signal in the 1 st irradiation and the 2 nd irradiation.

Fig. 4 (a) is a graph showing an oscillation command signal, a path selection signal, a timing chart of a slicing signal, and a waveform of a laser pulse when the 1 st laser pulse is sliced in processing by the laser processing apparatus according to the reference example, and fig. 4 (B) is a graph showing an oscillation command signal, a path selection signal, a timing chart of a slicing signal, and a waveform of a laser pulse when the 2 nd and 3 rd laser pulses are sliced.

Fig. 5 (a) is a graph showing an oscillation command signal, a path selection signal, a timing chart of a slicing signal, and a waveform of a laser pulse when the 1 st laser pulse is sliced in the laser processing apparatus according to the embodiment, and fig. 5 (B) is a graph showing an oscillation command signal, a path selection signal, a timing chart of a slicing signal, and a waveform of a laser pulse when the 2 nd and 3 rd laser pulses are sliced.

Fig. 6 (a) to (C) are timing charts based on an oscillation command signal, an operation state of a beam deflector, a path selection signal, and a cut signal in a laser processing apparatus according to another embodiment.

Fig. 7 is a timing chart of an oscillation command signal, an operation state of a beam deflector, a path selection signal, and a slicing signal in a laser processing apparatus according to still another embodiment.

Detailed Description

Fig. 1 is a schematic view of a laser processing apparatus according to an embodiment of the present invention and a reference example. The laser light source 10 receives the oscillation command signal S0 from the control device 55, performs laser oscillation, and outputs a pulse laser beam PLB. The laser light source 10 may be, for example, a carbon dioxide laser. For example, a rise in the oscillation command signal S0 indicates a start of oscillation, and a fall in the oscillation command signal S0 indicates a stop of oscillation.

An acousto-optic deflector (AOD)20 is disposed on a path of the pulse laser beam PLB output from the laser light source 10 and passing through the optical system 11. The optical system 11 includes, for example, a beam expander, an aperture, and the like. The AOD20 diverts the incident laser beam toward any one of a cut-off path PD of a beam cut-off (beam dump)13, a 1 st processing path MP1, and a 2 nd processing path MP 2. AOD20 includes an acousto-optic crystal 21, Transducers 22 and drivers 23. The transducer 22 is driven by a driver 23 to generate an elastic wave within the acousto-optic crystal 21.

The driver 23 is provided with a path switching terminal 24, a cut-out terminal 25, a 1 st diffraction efficiency adjustment knob 26, and a 2 nd diffraction efficiency adjustment knob 27. The path selection signal S1 is input from the control device 55 to the path switching terminal 24. One of the 1 st processing path MP1 and the 2 nd processing path MP2 is selected based on the path selection signal S1. The cut signal S2 is input from the control device 55 to the cut terminal 25. During the period when the cut signal S2 is not input, the AOD20 diverts the incident laser beam to the chopper path PD. While the slice signal S2 is input, the AOD20 diverts the laser beam to one of the 1 st processing path MP1 and the 2 nd processing path MP2 that is selected based on the path selection signal S1.

The 1 st diffraction efficiency adjustment knob 26 can adjust the diffraction efficiency when the input laser beam is diverted to the 1 st processing path MP 1. The diffraction efficiency when the input laser beam is diverted to the 2 nd processing path MP2 can be adjusted by the 2 nd diffraction efficiency adjustment knob 27. In this way, the AOD20 has a function of independently adjusting the diffraction efficiency into the 1 st processing path MP1 and the diffraction efficiency into the 2 nd processing path MP 2. By adjusting the diffraction efficiency, the light intensity of the laser beam diverted to the 1 st processing path MP1 and the 2 nd processing path MP2 can be adjusted. Instead of adjusting the diffraction efficiency by the 1 st diffraction efficiency adjustment knob 26 and the 2 nd diffraction efficiency adjustment knob 27, a command value of the diffraction efficiency may be input from the control device 55 to the actuator 23.

The laser beam output to the 1 st processing path MP1 is reflected by the mirror 30 and enters the beam deflector 31. The beam deflector 31 converts the traveling direction of the laser beam into a two-dimensional direction. The beam deflector 31 may use, for example, a pair of gaffeno scanners. The laser beam deflected by the beam deflector 31 is converged by the f θ lens 32 and then enters the object 33. Similarly, the laser beam output to the 2 nd processing path MP2 is incident on the object 43 via the mirror 40, the beam deflector 41, and the f θ lens 42. The

objects

33 and 43 are held on the table 50.

The beam deflectors 31 and 41 receive control signals G1 and G2 from the control device 55, respectively, and operate to cause the laser beam to enter the target position indicated. When the incident position of the laser beam is stabilized at the instructed target position, the control device 55 is notified of the stabilization completion.

Fig. 2 (a) is a schematic plan view of a printed circuit board 60 as an example of the

objects

33 and 43. The surface of the printed circuit board 60 is divided into a plurality of blocks 61. The size of each block 61 is set to a size that allows the incident position of the light beam to be moved based on the operation of the beam deflectors 31 and 41 (fig. 1).

A plurality of target locations 62 where holes should be formed are defined on the surface of the printed circuit board 60. The coordinates and the machining order of the plurality of target positions 62 are stored in the control device 55 (fig. 1) in advance. After holes are formed at all the target positions 62 in one block 61, the control device 55 moves the table 50 so as to dispose the unprocessed block 61 in an area where the beam deflectors 31 and 41 (fig. 1) can scan. After that, the unprocessed block 61 is processed in the same step.

Fig. 2 (B) shows a partial sectional view of the printed circuit board 60. An inner conductor pattern 66 is disposed on the surface of the core board 65. An insulating layer 67 is disposed on the core board 65 and the conductor pattern 66, and a conductor pattern 68 is disposed on the surface thereof. For example, a resin such as epoxy can be used for the core board 65 and the insulating layer 67. The

conductor patterns

66, 68 may be made of copper, for example.

Fig. 2 (C) shows the shape of a hole in the process of forming the hole in the drilling process by irradiating a pulse laser beam. Fig. 2 (C) shows an example of completing one drilling process by irradiating laser pulses 3 times. By irradiating the 1 st laser pulse, holes 68A are formed in the conductor pattern 68 on the surface. At this time, the surface layer portion of the insulating layer 67 on the bottom surface of the hole 68A is also removed, thereby forming the recess 67A.

By irradiating the 2 nd laser pulse, the concave portion 67A formed in the insulating layer 67 is deepened, thereby forming a concave portion 67B. By the irradiation of the 3 rd laser pulse, the recess 67B is further deepened, and a hole 67C reaching the conductor pattern 66 of the inner layer is formed. The preferred pulse width of the laser pulse varies depending on the material of the object to be processed. For example, the pulse widths of the 2 nd and 3 rd laser pulses are shorter than the pulse width of the 1 st laser pulse.

Next, a procedure of processing in one block 61 (fig. 2 a) will be described. After the 1 st laser pulse is irradiated to one target position 62, the incident position of the laser beam is moved to the next target position 62, and the 1 st laser pulse is irradiated to a new target position 62. When the 1 st laser pulse is irradiated to all the target positions 62 in one block 61, the 2 nd laser pulse is sequentially irradiated to all the target positions 62. After that, the 3 rd laser pulse is sequentially irradiated to all the target positions 62.

Further, the 2 nd laser pulse and the 3 rd laser pulse may be continuously irradiated to one target position 62 at a minute time interval without moving the incident position of the laser beam.

Fig. 3 shows a part of timing charts of the operation states of the beam deflectors 31 and 41 (fig. 1), the oscillation command signal S0, the path selection signal S1, and the slice signal S2 in the 1 st shot and the 2 nd shot. In the figure, two lines separated from each other in the vertical direction indicate the periods during which the

beam deflectors

31 and 41 operate, and one line indicates the stable period.

When the 1 st laser pulse is irradiated to one target position 62 ((a) in fig. 2), the controller 55 operates the

beam deflectors

31 and 41 to move the incident position of the laser beam to the next target position 62 to be processed. When both the

beam deflectors

31 and 41 are operated, that is, when the laser beam incident positions on the 1 st processing path MP1 and the 2 nd processing path MP2 are stable (time t1), the controller 55 starts transmitting the oscillation command signal S0 to the laser light source 10 (time t 2). Thereby, the output of the laser pulse of the pulse laser beam PLB outputted from the laser light source 10 is started. The rise of the oscillation command signal S0 corresponds to an oscillation start command of the laser light source 10. At this time, the 1 st processing path MP1 has been selected based on the path selection signal S1.

In a state where the 1 st processing path MP1 is selected, the controller 55 transmits a cut signal S2 having a predetermined pulse width PW1 (time t 3). Thereby, one laser pulse is cut into the 1 st processing path MP 1. Thereafter, the controller 55 transmits a path selection signal S1 for selecting the 2 nd processing path MP2 (time t 4). In a state where the 2 nd processing path MP2 is selected, the controller 55 transmits a cut signal S2 having a predetermined pulse width PW1 (time t 5). Thereby, one laser pulse is cut into the 2 nd processing path MP 2.

Thereafter, the controller 55 stops the transmission of the oscillation command signal S0 and returns the path selected based on the path selection signal S1 to the 1 st processing path MP1 (time t 7). The drop of the oscillation command signal S0 corresponds to an oscillation stop command for the laser light source 10. Further, control signals G1, G2 are sent to the

beam deflectors

31, 41, and the incident position of the laser beam is moved to the next target position 62 ((a) in fig. 2). In the case of the 2 nd and 3 rd laser pulse irradiation, substantially the same procedure as in the case of the 1 st laser pulse irradiation was repeated. Fig. 3 shows an example in which the pulse width of the cut signal S2 when the 2 nd laser pulse is cut is shorter than the pulse width of the cut signal S2 when the 1 st laser pulse is cut.

Before describing the laser processing apparatus according to the embodiment, a laser processing apparatus according to a reference example will be described with reference to (a) and (B) in fig. 4.

Fig. 4 (a) shows a timing chart of the oscillation command signal S0, the path selection signal S1, and the cut signal S2 at the time of cutting the 1 st laser pulse, and the waveform of the laser pulse. When the oscillation command signal S0 rises (time t2), the original laser pulse LP0 is output from the laser light source 10 (fig. 1). The laser light source 10 has a characteristic that the light intensity of the original laser pulse LP0 decreases with the passage of time. When the oscillation command signal S0 falls (time t6), the original laser pulse LP0 also falls.

When the pulse of the cut signal S2 is transmitted in a state where the 1 st processing path MP1 is selected based on the path selection signal S1 (time t3), the 1 st laser pulse LP1 is cut from the original laser pulse LP0 to the 1 st processing path MP 1. When the pulse of the cut signal S2 is transmitted in a state where the 2 nd processing path MP2 is selected based on the path selection signal S1 (time t5), the 2 nd laser pulse LP2 is cut from the original laser pulse LP0 to the 2 nd processing path MP 2. The pulse width of the 1 st laser pulse LP1 is the same as the pulse width of the 2 nd laser pulse LP 2.

The ratio of the light intensity of the 1 st laser pulse LP1 to the light intensity of the original laser pulse LP0 is determined by the setting of the 1 st diffraction efficiency adjustment knob 26. Likewise, the ratio of the light intensity of the 2 nd laser pulse LP2 to the light intensity of the original laser pulse LP0 is determined by the setting of the 2 nd diffraction efficiency adjustment knob 27. The light intensity of the original laser pulse LP0 when the 1 st processing path MP1 is selected based on the path selection signal S1 is stronger than the light intensity of the original laser pulse LP0 when the 2 nd processing path MP2 is selected based on the path selection signal S1. In order to eliminate the difference in intensity, the 1 st diffraction efficiency adjustment knob 26 and the 2 nd diffraction efficiency adjustment knob 27 are used to set the diffraction efficiency so that the diffraction efficiency in the 1 st processing path MP1 is lower than the diffraction efficiency in the 2 nd processing path MP 2.

Therefore, the attenuation of the light intensity when the 1 st laser pulse LP1 is cut from the original laser pulse LP0 is larger than the attenuation of the light intensity when the 2 nd laser pulse LP2 is cut from the original laser pulse LP 0. As a result, the pulse energy of the 1 st laser pulse LP1 and the pulse energy of the 2 nd laser pulse LP2 become almost equal. In other words, the diffraction efficiency into the 1 st processing path MP1 and the diffraction efficiency into the 2 nd processing path MP2 are adjusted so that the pulse energy of the 1 st laser pulse LP1 and the pulse energy of the 2 nd laser pulse LP2 become almost equal.

Fig. 4 (B) shows a timing chart of the oscillation command signal S0, the path selection signal S1, and the cut signal S2 at the time of cutting the 2 nd laser pulse, and the waveform of the laser pulse. The timing of cutting the 3 rd laser pulse is the same as the timing of cutting the 2 nd laser pulse. The pulse width PW2 of the slice signal S2 when the 2 nd laser pulse is cut is shorter than the pulse width PW1 of the slice signal S2 when the 1 st laser pulse is cut. Accordingly, the pulse width of the 2 nd irradiation original laser pulse LP0 is also shorter than that of the 1 st irradiation original laser pulse LP 0.

Even if the pulse width of the original laser pulse LP0 is short, the waveform of the original laser pulse LP0 up to and down is almost the same as the waveform of the corresponding portion of the original laser pulse LP0 of the 1 st shot. The elapsed time from the time point (time t3) at which the 1 st laser pulse LP1 is cut to the time point (time t5) at which the 2 nd laser pulse LP2 is cut is shorter in the 2 nd irradiation than in the 1 st irradiation. Therefore, the amount of decrease in light intensity of the original laser pulse LP0 from the cutting of the 1 st laser pulse LP1 to the cutting of the 2 nd laser pulse LP2 is smaller in the 2 nd irradiation than in the 1 st irradiation.

However, the diffraction efficiency into the 1 st processing path MP1 and the diffraction efficiency into the 2 nd processing path MP2 are the same at the 2 nd irradiation and the 1 st irradiation. As a result, the pulse energy of the 1 st laser pulse LP1 at the 2 nd irradiation is smaller than the pulse energy of the 2 nd laser pulse LP 2.

In the reference example shown in fig. 4 (a) and (B), it is difficult to make the pulse energy of the 1 st laser pulse LP1 output to the 1 st processing path MP1 and the pulse energy of the 2 nd laser pulse LP2 output to the 2 nd processing path MP2 almost the same in all of the 1 st irradiation, the 2 nd irradiation, and the 3 rd irradiation.

Next, a laser processing apparatus according to an embodiment will be described with reference to (a) and (B) of fig. 5. Hereinafter, differences from the reference examples shown in fig. 4 (a) and (B) will be described, and descriptions of the same configurations will be omitted.

Fig. 5 (a) shows a timing chart of the oscillation command signal S0, the path selection signal S1, and the cut signal S2 at the time of cutting the 1 st laser pulse, and the waveform of the laser pulse. This timing chart is the same as the timing chart of the reference example shown in fig. 4 (a).

Fig. 5 (B) shows a timing chart of the oscillation command signal S0, the path selection signal S1, and the cut signal S2 at the time of cutting the 2 nd laser pulse, and the waveform of the laser pulse. The timing of cutting the 3 rd laser pulse is the same as the timing of cutting the 2 nd laser pulse. As in the case of the reference example, the elapsed time from the time (time t2) when the control device 55 controls the laser light source 10 to start outputting the original laser pulse LP0 to the time (time t3) when the 1 st laser pulse LP1 is output to the 1 st processing path MP1 is constant in the 1 st shot and the 3 rd shot.

After the processing of the 1 st shot is finished, the processing of the 2 nd shot is performed, and the pulse width PW2 of the 1 st laser pulse LP1 outputted to the 1 st processing path MP1 is made different from the pulse width PW1 at the 1 st shot. Specifically, the pulse width PW2 is made shorter than the pulse width PW 1. Even when the pulse width is shortened, the elapsed time from the time (time t3) when the 1 st laser pulse LP1 is instructed to be cut to the time (time t5) when the 2 nd laser pulse LP2 is instructed to be cut to the 2 nd processing path MP2 does not change between the 1 st irradiation and the 2 nd irradiation.

As in the case of the reference example, the diffraction efficiency into the 1 st processing path MP1 and the diffraction efficiency into the 2 nd processing path MP2 are set so that the pulse energy of the 1 st laser pulse LP1 ((a) in fig. 5) of the 1 st shot and the pulse energy of the 2 nd laser pulse LP2 ((a) in fig. 5) are almost equal. In the embodiment, the portion of the pulse width of the original laser pulse LP0 where the 2 nd laser pulse LP2 is cut out to the 2 nd processing path MP2 is the same at the 1 st shot and the 2 nd shot. Therefore, the difference between the pulse energy of the 1 st laser pulse LP1 and the pulse energy of the 2 nd laser pulse LP2 can be reduced at the 2 nd irradiation as compared with the reference example.

Since the difference between the pulse energy of the 1 st laser pulse LP1 cut into the 1 st processing path MP1 and the pulse energy of the 2 nd laser pulse LP2 cut into the 2 nd processing path MP2 is small, the processing quality of the 1 st processing path MP1 and the processing quality of the 2 nd processing path MP2 can be matched. In order to improve the effect of reducing the difference between the pulse energy of the 1 st laser pulse LP1 and the pulse energy of the 2 nd laser pulse LP2, the pulse width of the original laser pulse LP0 is preferably set to be constant. In other words, it is preferable that the elapsed time between the transmission of the oscillation start command to the laser light source 10 and the transmission of the oscillation stop command is constant.

In the above-described embodiment, the laser pulse is irradiated 3 times to one processing point, but the number of times of irradiation of the laser pulse is not limited to 3. The number of laser pulses to irradiate one processing point may be 2 or 4 or more. When the laser pulse is irradiated 4 times or more to perform machining, the cutting timing of the laser pulse after the 3 rd time may be set to be the same as the cutting timing of the laser pulse after the 2 nd time.

Next, a laser processing apparatus according to another embodiment will be described with reference to (a) to (C) of fig. 6. Hereinafter, differences from the embodiments shown in fig. 1 to 3 and fig. 5 (a) and (B) will be described, and descriptions of the same structures will be omitted. In the embodiment shown in fig. 1 to 3 and fig. 5 (a) and (B), immediately after the timing at which the beam deflectors 31, 41 (fig. 1) are stabilized (timing t1 of fig. 3), the control device 55 starts sending the oscillation command signal S0 (timing t 2). In the embodiment described below, the timing at which the control device 55 starts to transmit the oscillation command signal S0 is limited to a certain range.

Fig. 6 (a) shows a timing chart of the oscillation command signal S0, the operation states of the

beam deflectors

31 and 41, the path selection signal S1, and the slice signal S2 in the laser processing apparatus according to the present embodiment. In fig. 6 (a), the operation states of the two

beam deflectors

31 and 41 are shown superimposed.

In the present embodiment, the lower limit value RPL and the upper limit value RPU of the repetition period of the laser pulse output from the laser light source 10 (fig. 1) are stored in the control device 55. The control device 55 sends an oscillation command signal S0 so that the repetition period of the laser pulses falls within the range between the lower limit value RPL and the upper limit value RPU.

As shown in fig. 6 a, when the elapsed time from the time (time t10) at which the oscillation start command is transmitted to the laser light source 10 (fig. 1) to the time (time t11) at which the operation of the

beam deflectors

31 and 41 is completed falls within the range between the lower limit value RPL and the upper limit value RPU, immediately after the time (time t11) at which the operation of the

beam deflectors

31 and 41 is completed, the control device 55 starts transmitting the oscillation command signal S0 (time t 12). The timing diagrams of the path select signal S1 and the cut signal S2 are the same as those of the embodiments shown in (a) and (B) of fig. 5.

As shown in fig. 6B, when the elapsed time from the rising time (time t10) of the oscillation command signal S0 to the time (time t13) when the operation of the

beam deflectors

31 and 41 is completed is shorter than the lower limit value RPL, the control device 55 does not transmit the oscillation command signal S0 to the laser light source 10 until the time corresponding to the lower limit value RPL elapses. The control device 55 starts transmission of the oscillation command signal S0 at a time point (time point t14) when a time corresponding to the lower limit RPL has elapsed from the rising time point (time point t10) of the oscillation command signal S0 in the previous cycle.

As shown in fig. 6C, if the operation of the

beam deflectors

31 and 41 has not been completed yet at the time (time t15) when the elapsed time from the rise time (time t10) of the oscillation command signal S0 in the previous cycle reaches the upper limit RPU, the controller 55 starts to transmit the oscillation command signal S0 to the laser light source 10 at that time. However, the control device 55 does not transmit the pulse of the cut signal S2. Accordingly, the original laser pulse output from the laser light source 10 is diverted to the chopper path PD (fig. 1) at all time periods within the pulse width thereof.

When the

beam deflectors

31 and 41 are stabilized (time t16), the transmission timing of the next oscillation command signal S0 is determined such that the elapsed time from the rise time (time t15) of the oscillation command signal S0 in the previous cycle falls within the range between the lower limit value RPL and the upper limit value RPU. For example, when the

beam deflectors

31 and 41 have stabilized at the time (time t17) when the time corresponding to the lower limit RPL has elapsed from the rising time (time t15) of the oscillation command signal S0 in the previous cycle, the controller 55 starts transmitting the oscillation command signal S0 at time t 17.

Next, the excellent effects of the examples shown in (a) to (C) of fig. 6 will be described. Even if the pulse width of the pulse laser beam output from the laser light source 10 is not changed, if the repetition frequency (repetition period) of the pulse is changed, the light intensity is varied and the pulse energy is also changed. In the embodiment shown in (a) to (C) in fig. 6, the variation in the repetition period of the pulse falls within the range between the lower limit value RPL and the upper limit value RPU. Therefore, the fluctuation of the pulse energy of the original laser pulse LP0 (fig. 5 (a) and (B)) can be suppressed. As a result, the variation in the pulse energy of the 1 st laser pulse LP1 and the 2 nd laser pulse LP2 diverted to the 1 st processing path MP1 and the 2 nd processing path MP2 can be suppressed.

Next, a laser processing apparatus according to still another embodiment will be described with reference to fig. 7. Hereinafter, differences from the embodiment shown in fig. 6 (a) to (C) will be described, and descriptions of the same configurations will be omitted.

In the embodiment shown in fig. 7, the lower limit value RPL and the upper limit value RPU of the repetition period of the pulses of the embodiment shown in (a) to (C) in fig. 6 are set to the same value. Therefore, the laser light source 10 outputs the original laser pulses LP0 at a constant repetition frequency regardless of the operation of the beam deflectors 31 and 41 (fig. 5 (a) and (B)).

When the

beam deflectors

31 and 41 have stabilized at the time when the original laser pulse LP0 rises (time t21), a pulse of the slicing signal S2 for slicing the 1 st laser pulse LP1 and the 2 nd laser pulse LP2 from the original laser pulse LP0 into the 1 st processing path MP1 and the 2 nd processing path MP2, respectively, is transmitted (times t22 and t 23). If the

beam deflectors

31 and 41 have not stabilized yet (time t24) at the time when the original laser pulse LP0 rises, the pulse of the cut signal S2 for cutting the laser pulse from the original laser pulse LP0 to the 1 st processing path MP1 and the 2 nd processing path MP2 is not transmitted. Thus, the original laser pulse LP0 is diverted to the shutter path PD (fig. 1).

In the embodiment shown in fig. 7, the repetition frequency of the pulses of the pulsed laser beam output from the laser light source 10 is constant, and therefore the stability of the pulse energy of the original laser pulses LP0 can be further improved. As a result, the pulse energies of the 1 st laser pulse LP1 and the 2 nd laser pulse LP2 switched to the 1 st processing path MP1 and the 2 nd processing path MP2 are also stabilized.

The present invention has been described above with reference to examples, but the present invention is not limited to these examples. For example, it will be apparent to those skilled in the art that various changes, modifications, combinations, and the like can be made.

Description of the symbols

10-laser light source, 11-optical system, 13-beam stop, 20-acousto-optic deflector (AOD), 21-acousto-optic crystal, 22-transducer, 23-driver, 24-path switching terminal, 25-cutting terminal, 26-1 st diffraction efficiency adjusting knob, 27-2 nd diffraction efficiency adjusting knob, 30-reflector, 31-beam deflector, 32-f theta lens, 33-processing object, 40-reflector, 41-beam deflector, 42-f theta lens, 43-processing object, 50-workbench, 55-control device, 60-printed circuit board, 61-block, 62-target position, 65-core board, 66-inner conductor pattern, 67-insulating layer, 67A, 67B-recess, 67C-hole, 68-surface conductor pattern, 68A-hole, G1, G2-control signal, LP 0-original laser pulse, LP 1-1 st laser pulse, LP 2-2 nd laser pulse, MP 1-1 st processing path, MP 2-2 nd processing path, PD-chopper path, PLB-pulsed laser beam, PW1, PW 2-pulse width, lower limit value of RPL-repetition period, upper limit value of RPU-repetition period, S0-oscillation command signal, S1-path selection signal, S2-cut signal.

Claims

1. A laser processing apparatus is characterized by comprising:

a laser light source that outputs a laser beam;

the control device repeatedly performs the following steps:

a step of instructing the laser light source to start oscillation;

a step of instructing the laser light source to stop oscillating,

in the course of repeating the steps described above,

the pulse width of the 1 st laser pulse to be cut into the 1 st processing path is changed, and the elapsed time from the transmission of the cutting signal to cut the 1 st laser pulse into the 1 st processing path to the transmission of the cutting signal to cut the 2 nd laser pulse into the 2 nd processing path is not changed,

the acousto-optic deflector has a function of independently adjusting diffraction efficiency to the 1 st processing path and diffraction efficiency to the 2 nd processing path, and is adjusted so that diffraction efficiency to the 1 st processing path becomes lower than diffraction efficiency to the 2 nd processing path.

2. Laser processing apparatus according to claim 1,

in the process of repeating the above steps, the control device keeps the time elapsed between the transmission of the instruction to start oscillation to the laser light source and the transmission of the instruction to stop oscillation unchanged.

3. Laser processing apparatus according to claim 1 or 2,

the control device stores a lower limit value and an upper limit value of a repetition period of pulses of the laser light source,

when the elapsed time from the time point of transmitting the instruction to start oscillation to the laser light source to the time point of ending the operation of the 1 st beam deflector and the 2 nd beam deflector is shorter than the lower limit value, the control device does not transmit the instruction to start oscillation to the laser light source until the time corresponding to the lower limit value elapses,

when the elapsed time from the start of the transmission of the instruction to start oscillation to the laser light source reaches the upper limit value before the 1 st beam deflector and the 2 nd beam deflector finish operation, the control device transmits the instruction to start oscillation to the laser light source and controls the acousto-optic deflector so as to divert the output original laser pulse to the chopper path.

4. Laser processing apparatus according to claim 3,

the lower limit value of the repetition period is the same as the upper limit value.