JP2018094594A - Laser pulse cutout apparatus and laser cutout method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser pulse cutout apparatus which hardly makes a difference in pulse energy of laser pulses for each processing route regardless of a change in the pulse width of laser pulses cut out to a plurality of processing routes.SOLUTION: A first laser pulse directing to a first processing route and a second laser pulse directing to a second processing route are cut out from one primitive laser pulse entering a beam deflector by making a controller give command to the beam deflector. The controller, when changing the pulse width of the first laser pulse and that of the second laser pulse, shifts both a rise point of time and a fall point of time of the first laser pulse reversely to each other, and shifts both a rise point of time and a fall point of time of the second laser pulse reversely to each other.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a laser pulse cutting device and a cutting method for cutting a plurality of laser pulses from one original laser pulse.

  A laser drill is known in which two laser pulses directed to two machining paths are cut out from one original laser pulse output from one laser oscillator and drilled by two axes (Patent Document 1). For example, an acousto-optic polarizing element (AOD) can be used for cutting out the laser pulse. When drilling a printed circuit board or the like, a laser pulse cut out from one original laser pulse and a laser pulse with a different pulse width cut out from the subsequent original laser pulse are made for one hole. Make it incident.

JP 2012-106266 A

  The waveform of the original laser pulse output from the laser oscillator is not rectangular, and the light intensity changes with time. When laser pulses having the same pulse width are cut out from one original laser pulse to a plurality of machining paths, the pulse energy of the laser pulse for each machining path does not become the same. In order to equalize the pulse energy of the laser pulse for each processing path, the diffraction efficiency to the first processing path is made different from the diffraction efficiency to the second processing path. During the processing period, the ratio of the diffraction efficiency to the first processing path and the diffraction efficiency to the second processing path is kept constant.

  The ratio of the diffraction efficiency is set so that the pulse energy of the laser pulse toward the first processing path and the second processing path is equal when the pulse width of the cut laser pulse is a certain value. If the pulse width of the cut laser pulse is changed under the condition that the ratio of diffraction efficiency is kept constant, a difference occurs in the pulse energy of the laser pulse toward the first machining path and the second machining path. I understood.

  An object of the present invention is to provide a laser pulse cutting device and a cutting method in which a difference in pulse energy of a laser pulse for each machining path hardly occurs even when the pulse width of a laser pulse cut into a plurality of machining paths changes. That is.

According to one aspect of the invention,
By giving a command to the beam deflector that directs the incident laser beam to either the first machining path or the second machining path directed to the workpiece by an instruction from the outside, the laser beam is incident on the beam deflector. A control device that cuts out a first laser pulse toward the first processing path and a second laser pulse toward the second processing path from one original laser pulse;
When the control device changes the pulse widths of the first laser pulse and the second laser pulse, the rising point and the falling point of the first laser pulse with reference to the rising point of the original laser pulse. Both are shifted in opposite directions, and a laser pulse cutting device is provided that shifts both the rising and falling points of the second laser pulse in opposite directions.

According to another aspect of the invention,
Cutting out the first laser pulse from the first original laser pulse toward the first processing path, and cutting out the second laser pulse toward the second processing path;
A third laser pulse is cut out from the second original laser pulse having the same pulse width as that of the first original laser pulse toward the first processing path, and the second laser pulse is directed toward the second processing path. Cutting out four laser pulses,
When the waveform of the second original laser pulse is superimposed on the waveform of the first original laser pulse, the rising and falling edges of the waveform of the third laser pulse are the rising edges of the waveform of the first laser pulse, respectively. And the rising and falling edges of the waveform of the fourth laser pulse are opposite to the rising and falling edges of the waveform of the second laser pulse, respectively. A laser pulse cutting method located at a location shifted in the direction is provided.

  The pulse widths of the first laser pulse and the second laser pulse are changed in a state where the cutting efficiency when cutting the laser pulse from the original laser pulse to the first machining path and the second machining path is kept constant. However, the pulse energies of the first laser pulse and the second laser pulse can be made substantially equal.

FIG. 1 is a schematic diagram of a laser processing apparatus (laser drill) in which a laser pulse cutting apparatus according to an embodiment is used. 2A to 2D are cross-sectional views of the printed circuit board, which is the object to be processed, before processing, during processing, and at the end of processing. FIG. 3A shows the waveform of the original laser pulse output from the laser light source (FIG. 1) and the first and second processing paths from the original laser pulse, respectively, cut out by the laser pulse cutting device according to the embodiment. FIG. 3B is a diagram illustrating waveforms of a first laser pulse and a second laser pulse, and FIG. 3B illustrates an original laser pulse and a first laser pulse and a second laser pulse cut out by a laser pulse cutting device according to a comparative example. It is a figure which shows these waveforms. FIG. 4 is a diagram showing the waveforms of the first laser pulse and the second laser pulse that are cut out using the laser pulse cutting device according to the modification, and the waveform of the original laser pulse. FIG. 5 is a diagram illustrating waveforms of a first laser pulse and a second laser pulse that are cut out using a laser pulse cutting device according to another modification, and a waveform of an original laser pulse.

  With reference to FIGS. 1 to 3B, a laser pulse cutting device according to an embodiment will be described.

  FIG. 1 is a schematic diagram of a laser processing apparatus (laser drill) in which a laser pulse cutting apparatus according to an embodiment is used. The laser light source 10 receives the oscillation command signal S0 from the control device 55, oscillates, and outputs a pulse laser beam PLB. For example, a carbon dioxide laser is used for the laser light source 10. For example, oscillation start is commanded by the rising edge of the oscillation command signal S0, and oscillation stop is commanded by the falling edge of the oscillation command signal S0.

  A beam deflector 20 is disposed in the path of the pulse laser beam PLB output from the laser light source 10 and passing through the optical system 11. As the beam deflector 20, for example, an acousto-optic deflection element (AOD) can be used. The optical system 11 includes, for example, a beam expander and an aperture. The beam deflector 20 directs the incident laser beam to one of the damper path PD, the first machining path MP1, and the second machining path MP2 toward the beam damper 13. The beam deflector 20 includes an acousto-optic crystal 21, a transducer 22, and a driver 23. The transducer 22 is driven by the driver 23 to generate an elastic wave in the acousto-optic crystal 21.

  The driver 23 is provided with a path switching terminal 24, a cutout terminal 25, a first diffraction efficiency adjustment knob 26, and a second diffraction efficiency adjustment knob 27. A route selection signal S <b> 1 is input from the control device 55 to the route switching terminal 24. One of the first machining path MP1 and the second machining path MP2 is selected by the path selection signal S1. The cut signal S <b> 2 is input from the control device 55 to the cut terminal 25. During the period when the cutting signal S2 is not input, the beam deflector 20 directs the incident laser beam to the damper path PD. During the period in which the cutting signal S2 is input, the beam deflector 20 directs the laser beam to the path selected by the path selection signal S1 out of the first machining path MP1 and the second machining path MP2. . When the control device 55 transmits the cutting signal S2 to the beam deflector 20, the laser pulse is transmitted from the original laser pulse output from the laser light source 10 to one of the first processing path MP1 and the second processing path MP2. Can be cut out.

  The first diffraction efficiency adjustment knob 26 can adjust the diffraction efficiency when the input laser beam is directed to the first machining path MP1. The second diffraction efficiency adjustment knob 27 can adjust the diffraction efficiency when the input laser beam is directed to the second machining path MP2. As described above, the beam deflector 20 has a function of independently adjusting the diffraction efficiency to the first machining path MP1 and the diffraction efficiency to the second machining path MP2. By adjusting the diffraction efficiency, the light intensity (power) of the laser beam directed to the first machining path MP1 and the second machining path MP2 can be adjusted. In other words, by adjusting the diffraction efficiency independently, the ratio between the attenuation rate of the laser pulse cut out to the first machining path MP1 and the attenuation rate of the laser pulse cut out to the second machining path MP2 can be adjusted. .

  The control device 55 and the beam deflector 20 function as a laser pulse cutting device that cuts out a laser pulse directed to the first machining path MP1 and a laser pulse directed to the second machining path MP2 from each laser pulse of the pulsed laser beam PLB. To do.

  The laser beam output to the first processing path MP1 is reflected by the mirror 30 and enters the beam scanner 31. The beam scanner 31 changes the traveling direction of the laser beam in a two-dimensional direction. As the beam scanner 31, for example, a pair of galvano scanners can be used. The laser beam deflected by the beam scanner 31 is converged by the fθ lens 32 and then enters the workpiece 33. Similarly, the laser beam output to the second processing path MP2 enters the processing object 43 via the mirror 40, the beam scanner 41, and the fθ lens 42. The workpieces 33 and 43 are held on the stage 50.

  The beam scanners 31 and 41 receive control signals G1 and G2 from the control device 55, respectively, and operate so that the laser beam enters the commanded target position. When the incident position of the laser beam is set to the commanded target position, the controller 55 is notified of the completion of setting.

  The display device 56 displays an image under the control of the control device 55. The operator operates the input device 57 to input various control parameters for performing laser processing. The control device 55 acquires the control parameter input from the input device 57 and stores it in the storage device. For the display device 56, for example, a liquid crystal display or the like is used. For the input device 57, for example, a keyboard, a pointing device, or the like is used. A touch panel may be used for the display device 56 and the input device 57.

  2A to 2D are cross-sectional views of the printed circuit board 60, which is a processing target, before processing, during processing, and at the end of processing. 2A to 2D show an example in which processing is performed with a laser pulse toward the first processing path MP1 (FIG. 1). Also in the second machining path MP2 (FIG. 1), drilling is performed in the same process as that shown in FIGS. 2A to 2D.

  As shown in FIG. 2A, the printed circuit board 60 has a three-layer structure in which a surface copper layer 62, a resin layer 61, and a bottom copper layer 63 are laminated. As shown in FIG. 2B, a recess 65 is formed by making a laser pulse LP11 incident on the surface copper layer 62. The recess 65 penetrates the surface copper layer 62 and reaches the middle of the resin layer 61 in the depth direction. The laser pulse LP11 is cut out from the original laser pulse output from the laser light source 10. A laser pulse toward the second machining path MP2 is further cut out from the original laser pulse from which the laser pulse LP11 is cut out, and the same machining is performed in the second machining path MP2.

  As shown in FIG. 2C, the laser beam LP12 is incident on the bottom surface of the recess 65 to deepen the recess 65. At this time, the recess 65 does not reach the bottom copper layer 63. The laser pulse LP12 is cut out from another original laser pulse following the original laser pulse from which the laser pulse LP11 (FIG. 2B) is cut out. From this original laser pulse, a laser pulse toward the second machining path MP2 is further cut out, and the same machining is performed also in the second machining path MP2.

  As shown in FIG. 2D, the recess 65 is made deeper by making the laser pulse LP13 incident on the bottom surface of the recess 65. At this point, the recess 65 reaches the bottom copper layer 63, and a blind via hole is formed. The laser pulse LP13 is cut out from another original laser pulse following the original laser pulse from which the laser pulse LP12 (FIG. 2C) is cut out. From this original laser pulse, a laser pulse toward the second machining path MP2 is further cut out, and the same machining is performed also in the second machining path MP2.

  The laser pulse LP11 (FIG. 2B) has a pulse energy that can penetrate the surface copper layer 62. The pulse energy of the laser pulse LP12 (FIG. 2C) is smaller than the pulse energy of the laser pulse LP11. The pulse energy of the laser pulse LP12 is set to such a magnitude that the concave portion 65 does not reach the bottom copper layer 63 and the resin layer 61 can be dug. The pulse energy of the laser pulse LP13 (FIG. 2D) is equal to the pulse energy of the laser pulse LP12 (FIG. 2C).

  In the example shown in FIGS. 2A to 2D, one blind via hole is formed by three laser pulses LP11, LP12, and LP13. However, one blind via hole may be processed using four or more laser pulses. . The number of laser pulses used for processing and the pulse energy of the laser pulses LP12 and LP13 are adjusted according to the thickness of the resin layer 61, and are optimized from the viewpoint of reducing damage to the bottom copper layer 63. For example, the pulse energy of the laser pulse LP13 may be sufficient to expose the bottom copper layer 63, and may be smaller than the pulse energy of the laser pulse LP12. By reducing the pulse energy of the laser pulse LP13, damage to the bottom copper layer 63 can be reduced.

  3A shows the waveform of the original laser pulse LO output from the laser light source 10 (FIG. 1), and the first cutting path MP1 and the second processing path MP2 (FIG. 1) cut out from the original laser pulse LO, respectively. It is a figure which shows the waveform of 1 laser pulse LP1 and 2nd laser pulse LP2.

  As shown in the upper part of FIG. 3A, the original laser pulse LO rises at the rise time t0 and falls sharply from the fall time t5. The slope of the light intensity from the rising time t0 to the falling time t5 is not constant, and the slope becomes gentle with time. The control device 55 cuts out the first laser pulse LP1 toward the first machining path MP1 from the first half portion of the original laser pulse LO, and the second laser beam LP2 toward the second machining path MP2 from the latter half portion of the original laser pulse LO. The laser pulse LP2 is cut out. The pulse width of the first laser pulse LP1 and the pulse width of the second laser pulse LP2 are the same.

  The diffraction efficiency for the first machining path MP1 by the beam deflector 20 is set to 100%. Therefore, the light intensity (waveform height) of the first laser pulse LP1 matches the light intensity (waveform height) of the original laser pulse LO. The diffraction efficiency of the beam deflector 20 toward the second machining path MP2 is set to be less than 100%. For this reason, the light intensity (waveform height) of the second laser pulse LP2 is lower than the light intensity (waveform height) of the original laser pulse LO. The ratio of the diffraction efficiency to the first processing path MP1 and the diffraction efficiency to the second processing path MP2 is such that the pulse energy of the first laser pulse LP1 is equal to the pulse energy of the second laser pulse LP2. It is set to be. The pulse energy of the laser pulse corresponds to the area of the pulse waveform (a value obtained by integrating the pulse waveform over time).

  The lower part of FIG. 3A shows an example in which the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are shorter than those shown in the upper part. Compared with the pulse waveform shown in the upper part of FIG. 3A, the control device 55 shifts the rising time t1 of the first laser pulse LP1 backward with reference to the rising time t0 of the original laser pulse LO, and the falling time t2. Is shifted forward to shorten the pulse width of the first laser pulse LP1. Similarly, the rise time t3 of the second laser pulse LP2 is shifted backward and the fall time t4 is shifted forward with reference to the rise time t0 of the original laser pulse LO, so that the second laser pulse LP2 Reduce the pulse width.

  In order to increase the pulse width of the first laser pulse LP1, the rising time t1 of the first laser pulse LP1 may be shifted forward and the falling time t2 may be shifted backward. Similarly, in order to increase the pulse width of the second laser pulse LP2, the rising point t3 of the second laser pulse LP2 may be shifted forward and the falling point t4 may be shifted backward.

  As described above, the control device 55 changes the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 by shifting the rising point and the falling point of the laser pulse in opposite directions. To do. At this time, when the waveform of the lower original laser pulse LO in FIG. 3A is superimposed on the waveform of the upper original laser pulse LO, the rising and falling of the waveform of the first laser pulse LP1 in the lower stage are the first in the upper stage, respectively. Is located at a position where the rise and fall of the waveform of the laser pulse LP1 are shifted in opposite directions, and the rise and fall of the waveform of the second laser pulse LP2 in the lower stage are the second laser pulses in the upper stage, respectively. It is located at a location where the rise and fall of the waveform of Lp2 are shifted in opposite directions.

  Next, the excellent effect of the embodiment shown in FIG. 3A will be described in comparison with the comparative example shown in FIG. 3B.

  FIG. 3B shows the waveform of the original laser pulse LO, and the first laser pulse LP1 and the second laser cut out from the original laser pulse LO into the first machining path MP1 and the second machining path MP2 by the method according to the comparative example. It is a figure which shows the waveform of pulse LP2.

  The waveform shown in the upper part of FIG. 3B is the same as the waveform shown in the upper part of FIG. 3A. The diffraction of the beam deflector 20 (FIG. 1) so that the pulse energy of the first laser pulse LP1 is equal to the pulse energy of the second laser pulse LP2 at the pulse width shown in the upper part of FIG. 3B. Efficiency is adjusted.

  The lower part of FIG. 3B shows an example in which the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are shorter than those shown in the upper part. The rise time t1 of the first laser pulse LP1 is fixed with reference to the rise time t0 of the original laser pulse LO, and only the fall time t2 is shifted forward. Similarly, the rising time t3 of the second laser pulse LP2 is fixed, and only the falling time t4 is shifted forward.

  The slope of the waveform of the original laser pulse LO at the position where the first laser pulse LP1 is cut out is steeper than the slope of the waveform of the original laser pulse LO at the position where the second laser pulse LP2 is cut out. For this reason, when the pulse width is shortened by the method according to the comparative example, the pulse energy of the first laser pulse LP1 is greatly reduced as compared with the pulse energy of the second laser pulse LP2. When the diffraction efficiency of the beam deflector 20 (FIG. 1) is unchanged, the pulse energy of the first laser pulse LP1 becomes smaller than the pulse energy of the second laser pulse LP2. When the pulse energy of the first laser pulse LP1 and the pulse energy of the second laser pulse LP2 are different, the first machining path MP1 and the second machining path MP2 can perform machining of the same quality. It will disappear.

  Each time the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed, the diffraction efficiency into the first machining path MP1 and the second machining path MP2 is corrected, thereby the first laser pulse. It is possible to make the pulse energy of LP1 equal to the pulse energy of the second laser pulse LP2. However, it is difficult to readjust the diffraction efficiency each time the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed.

  When the pulse width is changed, it is preferable to maintain a state where the pulse energy of the first laser pulse LP1 and the pulse energy of the second laser pulse LP2 are substantially equal without readjusting the diffraction efficiency.

  In the embodiment shown in FIG. 3A, when the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed, both the rising time point and the falling time point of the laser pulse are shifted in opposite directions. Let Therefore, the difference between the change rate of the pulse energy of the first laser pulse LP1 and the change rate of the pulse energy of the second laser pulse LP2 when the pulse width is changed is smaller than that in the comparative example. . As a result, variation in machining quality between the first machining path MP1 and the second machining path MP2 can be reduced.

  Next, with reference to FIG. 4, the cutting method by the laser pulse cutting device by the modification of the said Example is demonstrated.

  FIG. 4 is a diagram showing the waveforms of the first laser pulse LP1 and the second laser pulse LP2 cut out using the laser pulse cutting device according to the modification, and the waveform of the original laser pulse LO. In this modification, a first reference time tr1 and a second reference time tr2 fixed within the pulse width of the original laser pulse LO are set. For example, for example, the elapsed time from the rising point t0 of the original laser pulse LO to the first reference time tr1 and the second reference time tr2 is constant in all the original laser pulses LO.

  The first reference time tr1 and the second reference time tr2 are a value H1 obtained by multiplying the height of the waveform of the original laser pulse LO at the first reference time tr1 by the diffraction efficiency to the first machining path MP1, and the first reference time tr1. A value H2 obtained by multiplying the height of the waveform of the original laser pulse LO at the second reference time tr2 by the diffraction efficiency to the second machining path MP2 is set to be equal.

  When changing the pulse widths of the first laser pulse LP1 and the second laser pulse LP2, the controller 55 includes the first reference time tr1 within the pulse width of the first laser pulse LP1, and the second The rise time and fall time of each laser pulse are shifted so that the second reference time tr2 is included in the pulse width of the laser pulse LP2.

  As shown in the upper part of FIG. 4, the control device 55 sets the time width TF of the waveform of the first laser pulse LP1 extending forward from the first reference time tr1 and the first laser pulse LP1 extending backward. The first laser pulse LP1 is cut out so that the time width TB of the waveform becomes equal. Similarly, the time width TF of the waveform of the second laser pulse LP2 extending forward from the second reference time tr2 is equal to the time width TB of the waveform of the second laser pulse LP2 extending backward. Then, the second laser pulse LP2 is cut out. The time width TF of the first laser pulse LP1 is equal to the time width TF of the second laser pulse LP2, and the time width TB of the first laser pulse LP1 is equal to the time width TB of the second laser pulse LP2.

  When the pulse width is shortened, as shown in the lower part of FIG. 4, the time width TF of the waveform of the first laser pulse LP1 extending forward from the first reference time tr1 and the first laser pulse extending backward are provided. The time width TB of the LP1 waveform is shortened. Similarly, the time width TF of the waveform of the second laser pulse LP2 extending forward from the second reference time tr2 and the time width TB of the waveform of the second laser pulse LP2 extending backward are shortened. At this time, the control device 55 shortens the pulse width while maintaining the condition that the time width TF and the time width TB are equal.

  Next, a method for determining the first reference time tr1 and the second reference time tr2 will be described. First, the maximum value of the pulse width of the laser pulse necessary for drilling is determined. For example, the maximum value of the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 is determined from the pulse energy necessary for forming the recess 65 (FIG. 2B) penetrating the surface copper layer 62 (FIG. 2A). Can be determined.

  Based on the maximum value of the pulse widths of the first laser pulse LP1 and the second laser pulse LP2, the pulse width of the original laser pulse LO (FIG. 4) is determined. The pulse width of the original laser pulse LO is, for example, a standby time width required from the rising time of the original laser pulse LO to the rising time of the first laser pulse LP1, and the second width from the falling time of the first laser pulse LP1. The first laser pulse LP1 and the standby time width required until the rising time of the laser pulse LP2 and the standby time width required from the falling time of the second laser pulse LP2 to the falling time of the original laser pulse LO It can be determined by adding the maximum value of the pulse width of the second laser pulse LP2.

  The center point on the time axis of the waveform of the first laser pulse LP1 when the first laser pulse LP1 and the second laser pulse LP2 having the maximum pulse width are cut out from the original laser pulse LO is the first reference time tr1. The center point on the time axis of the waveform of the second laser pulse LP2 may be set as the second reference time tr2. If the diffraction efficiency of the beam deflector 20 is set based on the ratio between the height of the waveform of the original laser pulse LO at the first reference time tr1 and the height of the waveform of the original laser pulse LO at the second reference time tr2. Good.

  The above-mentioned three waiting time widths are set in the control device 55 in advance. When the operator operates the input device 57 to input the maximum value of the pulse width of the laser pulse necessary for processing, the control device 55 is based on the input maximum value of the pulse width and a preset standby time width. The pulse width of the original laser pulse LO, the first reference time tr1, and the second reference time tr2 are calculated.

  In the modification shown in FIG. 4, even when the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed, the center of the waveform of the first laser pulse LP1 on the time axis is the first reference. The time point tr1 is fixed, and the center of the waveform of the second laser pulse LP2 on the time axis is fixed at the second reference time tr2. For this reason, even if the pulse width is changed, the light intensity at the center position on the time axis of the waveforms of the first laser pulse LP1 and the second laser pulse LP2 (the height of the laser pulse waveform) remains unchanged. Therefore, in the modification shown in FIG. 4, even if the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed, the pulse energies of both can be maintained substantially equal.

  Next, a cutting method using a laser pulse cutting device according to another modification of the above embodiment will be described with reference to FIG.

  FIG. 5 is a diagram showing the waveforms of the first laser pulse LP1 and the second laser pulse LP2 cut out using the laser pulse cutting device according to the present modification, and the waveform of the original laser pulse LO.

  Also in the present modification, as in the modification shown in FIG. 4, the first reference time tr1 and the second reference time tr2 fixed within the pulse width of the original laser pulse LO are set.

  As shown in the upper part of FIG. 5, the control device 55 (FIG. 1) multiplies the height H1 of the waveform of the first laser pulse LP1 at the first reference time tr1 by the pulse width PW of the first laser pulse. The first laser pulse LP1 is cut out so that the value H1 × PW and the area A1 of the waveform of the first laser pulse LP1 are equal. If the slope of the waveform of the original laser pulse LO is linear, the first reference time tr1 is positioned at the center of the period from the rising edge to the falling edge of the first laser pulse LP1. Actually, since the waveform of the original laser pulse LO is a curve, strictly speaking, the first reference time tr1 deviates from the center of the period from the rising edge to the falling edge of the first laser pulse LP1. The same applies to the relationship between the second laser pulse LP2 and the second reference time tr2. That is, a value H2 × PW obtained by multiplying the height H2 of the waveform of the second laser pulse LP2 at the second reference time tr2 by the pulse width PW of the second laser pulse, and the area of the waveform of the second laser pulse LP2. A2 is equal.

  As shown in the lower part of FIG. 5, even when the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are shortened, the relationship between the first laser pulse LP1 and the first reference time tr1, The relationship between the second laser pulse LP2 and the second reference time tr2 satisfies the above condition. That is, H1 × PW is equal to the area A1 of the waveform of the first laser pulse LP1, and H2 × PW is equal to the area A2 of the waveform of the second laser pulse LP2.

  Under the condition that the waveform of the original laser pulse LO as the cut-out source is substantially constant, the height of the waveform at the first reference time tr1 and the second reference time tr2 is substantially constant. For this reason, when the pulse widths of the first laser pulse LP1 and the second laser pulse LP2 are changed by the method according to this modification, the pulse energies of both after the pulse width change are substantially the same.

  In the above-described embodiments and modifications, laser pulses are cut out from one original laser pulse LO to two machining paths, respectively, but laser pulses may be cut out to three or more machining paths. Also in this case, when the pulse width of the laser pulse to be cut out is changed, the rising and falling points of the laser pulse to be cut out may be shifted by the same method as in the above-described embodiment or modification.

  Each of the above-described embodiments is an exemplification, and needless to say, partial replacement or combination of the configurations shown in the different embodiments is possible. About the same effect by the same composition of a plurality of examples, it does not refer to every example one by one. Furthermore, the present invention is not limited to the embodiments described above. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Laser light source 11 Optical system 13 Beam damper 20 Beam deflector 21 Acousto-optic crystal 22 Transducer 23 Driver 24 Path switching terminal 25 Cutting terminal 26 First diffraction efficiency adjustment knob 27 Second diffraction efficiency adjustment knob 30 Mirror 31 Beam scanner 32 fθ lens 33 object to be processed 40 mirror 41 beam scanner 42 fθ lens 43 object to be processed 50 stage 55 controller 56 display device 57 input device 60 printed circuit board 61 resin layer 62 surface copper layer 63 bottom copper layer 65 recess LO original laser pulse LP1 First laser pulse LP2 Second laser pulse

Claims (5)

By giving a command to the beam deflector that directs the incident laser beam to either the first machining path or the second machining path directed to the workpiece by an instruction from the outside, the laser beam is incident on the beam deflector. A control device that cuts out a first laser pulse toward the first processing path and a second laser pulse toward the second processing path from one original laser pulse;
When the control device changes the pulse widths of the first laser pulse and the second laser pulse, the rising point and the falling point of the first laser pulse with reference to the rising point of the original laser pulse. Both are shifted in opposite directions to each other, and both the rising time point and falling time point of the second laser pulse are shifted in opposite directions.   The control device includes a first reference time point and a second reference time point fixed within the pulse width of the original laser pulse, respectively, within the pulse widths of the first laser pulse and the second laser pulse. Thus, the first laser pulse has a waveform height equal to that of the first laser pulse at the first reference time point and a waveform height of the second laser pulse at the second reference time point. The laser pulse cutting device according to claim 1, wherein a pulse width of the second laser pulse is changed.   The control device is configured such that a time width of the waveform of the first laser pulse extending forward from the first reference time is equal to a time width of the waveform of the first laser pulse extending backward. The time width of the waveform of the second laser pulse extending forward from the second reference time point is equal to the time width of the waveform of the second laser pulse extending backward. The laser pulse cutting device according to claim 2, wherein a pulse width of the second laser pulse is changed.   The control device includes a value obtained by multiplying a height of the waveform of the first laser pulse at the first reference time by a pulse width of the first laser pulse, and an area of the waveform of the first laser pulse. And a value obtained by multiplying the height of the waveform of the second laser pulse at the second reference time by the pulse width of the second laser pulse, and the area of the waveform of the second laser pulse. The laser pulse cutting device according to claim 2, wherein pulse widths of the first laser pulse and the second laser pulse are changed so as to be equal. Cutting out the first laser pulse from the first original laser pulse toward the first processing path, and cutting out the second laser pulse toward the second processing path;
A third laser pulse is cut out from the second original laser pulse having the same pulse width as that of the first original laser pulse toward the first processing path, and the second laser pulse is directed toward the second processing path. Cutting out four laser pulses,
When the waveform of the second original laser pulse is superimposed on the waveform of the first original laser pulse, the rising and falling edges of the waveform of the third laser pulse are the rising edges of the waveform of the first laser pulse, respectively. And the rising and falling edges of the waveform of the fourth laser pulse are opposite to the rising and falling edges of the waveform of the second laser pulse, respectively. Laser pulse cutting method located at a location shifted in the direction.

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