JP6682146B2 - Laser pulse cutting device and laser processing method - Google Patents

Description

  The present invention relates to a laser pulse cutting device and a laser processing method.

  When making a hole in a printed circuit board or the like by using a laser drill, usually, a plurality of laser pulses are made to enter one hole. Patent Document 1 discloses a laser processing method in which a plurality of laser pulses are cut out from one original laser pulse output from a laser oscillator and punching is performed.

JP 2012-106266 A

  When the holes (blind via holes) are formed in the surface copper layer and the resin layer by leaving the bottom copper layer of the three-layer printed board including the surface copper layer, the resin layer, and the bottom copper layer, the bottom copper layer is damaged. It is required not to give. As the bottom copper layer becomes thinner, it becomes more difficult to form blind via holes without damaging the bottom copper layer.

  When holes are formed on both the front surface copper layer side and the bottom surface copper layer side on a three-layer printed circuit board and the two holes are combined near the center of the resin layer to form a through hole, the center of the resin layer is formed. It is required to make the hole diameter in the hole smaller than the hole diameter in the front surface copper layer and the bottom surface copper layer and reduce the variation in the hole diameter. As the resin layer becomes thicker, it becomes difficult to reduce the variation in the hole diameter at the center of the resin layer.

  In order to form the blind via hole without damaging the bottom copper layer, it is preferable to finely adjust the laser irradiation conditions. Similarly, it is preferable to adjust the laser irradiation condition more finely in order to reduce the variation in the hole diameter of the through hole in the center of the resin layer.

  An object of the present invention is to provide a laser pulse cutting device capable of more finely adjusting laser irradiation conditions. Another object of the present invention is to provide a laser processing method capable of finely adjusting laser irradiation conditions.

According to one aspect of the invention,
A beam deflector that directs an incident laser beam to a processing path toward a processing object according to a command from the outside,
A controller having a function of cutting out a plurality of laser pulses having different pulse widths and pulse energies from one original laser pulse incident on the beam deflector toward the processing path by giving a command to the beam deflector. A laser pulse cutting device having the same is provided.

According to another aspect of the invention,
A control device for controlling a beam deflector, which directs a laser beam from an incident laser beam to a processing path toward a processing object, in one of the control modes selected from a plurality of control modes,
A display device for displaying an image under the control of the control device,
And an input device,
Each of the control modes is a control parameter including a pulse width of a laser pulse cut out from the original laser pulse incident on the beam deflector toward the processing path, the number of laser pulses cut out, and an interval between laser pulses. Stipulated,
A laser pulse cutting device is provided, wherein the control device causes the display device to display image information for prompting the input of the control parameter, and acquires the control parameter input from the input device.

According to yet another aspect of the present invention,
A laser processing method for laser processing an object to be processed is provided by cutting out a plurality of laser pulses having different pulse widths and pulse energies from one original laser pulse toward a processing path and making the laser pulses incident on the object to be processed.

  By cutting out a plurality of laser pulses having different pulse widths and pulse energies from one original laser pulse, the laser irradiation conditions can be adjusted more finely. The operator can easily input the value of the control parameter by looking at the image display that prompts the user to input the control parameter that defines the plurality of control modes.

FIG. 1 is a schematic diagram of a laser processing device (laser drill) in which a laser pulse cutting device according to an embodiment is used. 2A to 2D are cross-sectional views of a printed circuit board that is a processing target before processing, during processing, and at the end of processing. FIG. 3A is a graph showing an outline of a laser pulse waveform when a printed circuit board is processed by the method according to the embodiment, and FIGS. 3B and 3C are laser pulse waveforms when the printed circuit board is processed by the method according to the comparative example. It is a graph which shows the outline of a waveform. FIG. 4 is a diagram showing an example of a dialog displayed on the display device of the laser pulse cutting device according to the embodiment. 5A to 5E are cross-sectional views of a printed circuit board in each step of forming a through hole by a laser processing method according to another embodiment. FIG. 6 is a graph showing the relationship between the pulse numbers of the laser pulse LP32 and the laser pulse LP42 and the variation in the inner diameter of the through hole in the central portion in the thickness direction. FIG. 7 is a graph showing an example of the waveform of a laser pulse when forming a through hole by the method according to the embodiment shown in FIGS. 5A to 5E. FIG. 8A is a graph showing an example of a pulse train of a plurality of laser pulses LP32 when processing is performed by the method according to the embodiment shown in FIGS. 5A to 5E, and FIG. 8B is when performing processing by the method according to the comparative example. 5 is a graph showing an example of a pulse train of a plurality of laser pulses LP32.

  A laser pulse cutting device and a laser processing method according to an embodiment will be described with reference to FIGS.

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

  A beam deflector 20 is arranged in the path of the pulsed laser beam PLB output from the laser light source 10 and passing through the optical system 11. For the beam deflector 20, for example, an acousto-optic deflecting element (AOD) can be used. The optical system 11 includes, for example, a beam expander and an aperture. The beam deflector 20 redirects the incident laser beam to any one of the damper path PD, the first processing path MP1, and the second processing 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. The route selection signal S1 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 cutout signal S2 is input from the control device 55 to the cutout terminal 25. The beam deflector 20 directs the incident laser beam to the damper path PD while the cutout signal S2 is not input. While the cutout signal S2 is being input, the beam deflector 20 directs the laser beam to one of the first processing path MP1 and the second processing path MP2 that is selected by the path selection signal S1. .

  The first diffraction efficiency adjustment knob 26 can adjust the diffraction efficiency when the input laser beam is directed to the first processing path MP1. The second diffraction efficiency adjustment knob 27 can adjust the diffraction efficiency when the input laser beam is directed to the second processing path MP2. In this way, the beam deflector 20 has a function of independently adjusting the diffraction efficiency for the first processing path MP1 and the diffraction efficiency for the second processing path MP2. By adjusting the diffraction efficiency, the light intensity of the laser beam directed to the first processing path MP1 and the second processing path MP2 can be adjusted. Instead of the method of adjusting the diffraction efficiency with the first diffraction efficiency adjusting knob 26 and the second diffraction efficiency adjusting knob 27, the controller 55 may input a command value of the diffraction efficiency to the driver 23.

  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 processing path MP1 and a laser pulse directed to the second processing 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 into a two-dimensional direction. For 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 object 33 to be processed. Similarly, the laser beam output to the second processing path MP2 enters the object to be processed 43 via the mirror 40, the beam scanner 41, and the fθ lens 42. The processing objects 33 and 43 are held on the stage 50.

  The beam scanners 31 and 41 operate to receive the control signals G1 and G2 from the control device 55, respectively, so that the laser beam is incident on 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 settling.

  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 input control parameter from the input device 57 and stores it in the storage device. As the display device 56, for example, a liquid crystal display or the like is used. As 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 an object to be processed, before processing, during processing, and at the end of processing. As shown in FIG. 2A, the printed board 60 has a three-layer structure in which a front surface copper layer 62, a resin layer 61, and a bottom surface copper layer 63 are laminated.

  As shown in FIG. 2B, the laser pulse LP11 is incident on the surface copper layer 62 to form the recess 65. The concave portion 65 reaches from the surface of the surface copper layer 62 to the middle of the depth direction of the resin layer 61.

  As shown in FIG. 2C, the recess 65 is deepened by, for example, entering two laser pulses LP12 into the bottom surface of the recess 65. At this point, the concave portion 65 has not reached the bottom copper layer 63.

  As shown in FIG. 2D, the recess 65 is made deeper by making, for example, two laser pulses 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.

  Laser pulse LP11 (FIG. 2B) has a pulse energy capable of penetrating surface copper layer 62. The pulse energy of laser pulse LP12 (FIG. 2C) is smaller than the pulse energy of 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 surface copper layer 63 and the resin layer 61 can be dug forward. The pulse energy of the laser pulses LP11 and LP12 is set to a suitable value depending on the material, thickness, etc. of the object to be processed.

  The pulse energy of the laser pulse LP13 (FIG. 2D) is smaller than the pulse energy of the laser pulse LP12 (FIG. 2C), and does not substantially damage the bottom surface copper layer 63 even when it is incident on the exposed bottom surface copper layer 63. Is set to.

  FIG. 3A is a graph showing an outline of the waveform of a laser pulse when processing the printed circuit board 60. Original laser pulses LO1 and LO2 are output from the laser light source 10. The waveforms of the original laser pulses LO1 and LO2 include a portion where the light intensity rises from the time of rising, a portion where the light intensity changes gradually, and a portion where the light intensity falls sharply. The laser pulse directed to the first processing path MP1 and the second processing path MP2 is cut out from a portion where the change in light intensity is gentle.

  A laser pulse LP11 directed to the first processing path MP1 is cut out from the first half of the original laser pulse LO1, and a laser pulse LP21 directed to the second processing path MP2 is cut out from the latter half. The laser pulse LP11 forms the recess 65 in the processing step shown in FIG. 2B.

  Two laser pulses LP12 and two laser pulses LP13 directed to the first machining path MP1 are cut out from the first half of the original laser pulse LO2, and two laser pulses LP22 and LP22 directed to the second machining path MP2 from the latter half. Two laser pulses LP23 are cut out.

  The pulse width of the laser pulse LP13 is shorter than the pulse width of the laser pulse LP12. Therefore, the pulse energy of the laser pulse LP13 becomes smaller than the pulse energy of the laser pulse LP12. Regarding the pulse width and the pulse energy, the relationship between the laser pulses LP22 and LP23 is the same as the relationship between the laser pulses LP12 and LP13. The two laser pulses LP12 are used for digging the recess 65 in the processing step shown in FIG. 2C. The two laser pulses LP13 are used for the purpose of making the concave portion 65 reach the bottom surface copper layer 63 in the processing step shown in FIG. 2D.

  As shown in FIG. 3A, the laser pulse cutting device including the control device 55 and the beam deflector 20 changes the pulse width and the pulse width from one original laser pulse LO2 toward one processing path, for example, the first processing path MP1. It has a function of cutting out a plurality of laser pulses LP12 and LP13 having different pulse energies. Similarly, the laser pulse cutting device according to the embodiment has a function of cutting a plurality of laser pulses LP22 and LP23 having different pulse widths and pulse energies from one original laser pulse LO2 even toward the second processing path MP2. . Therefore, the laser processing apparatus using the laser pulse cutting apparatus according to the embodiment can simultaneously perform laser processing on the two processing objects 33 and 43 (FIG. 1).

  Next, an excellent effect of the laser pulse cutting device according to the embodiment will be described by comparing with the comparative example shown in FIGS. 3B and 3C. The laser pulse cutting device according to the comparative example does not have a function of changing the pulse width of the laser pulse cut from one original laser pulse.

  FIG. 3B is a graph showing an example of a schematic waveform of a laser pulse when performing laser processing using the laser pulse cutting device according to the comparative example. The laser pulse cutting device according to the comparative example does not have a function of changing the pulse width of the laser pulse cut out from one original laser pulse, so that the laser pulse LP12 and the laser pulse LP13 cut out from the original laser pulse LO2 have the same pulse width. turn into.

  In the processing step of reaching the bottom surface copper layer 63 of the concave portion 65 shown in FIG. 2D, when processing is performed with the laser pulse LP13 having the same pulse width as the pulse width of the laser pulse LP12, the pulse energy is too high and the bottom surface copper layer 63 is formed. Damages. In order to reduce the pulse energy of the laser pulse LP13 to the extent that the bottom copper layer 63 is not damaged, the pulse energy of the laser pulse LP12 must also be reduced. For this reason, the processing speed is remarkably slowed in the processing step of digging the recess 65 shown in FIG. 2C.

  FIG. 3C is a graph showing an outline of a laser pulse waveform when performing drilling using the laser pulse cutting device according to the comparative example so as not to damage the bottom surface copper layer 63. From the original laser pulse LO2, only two laser pulses LP12 used in the processing step of digging the recess 65 of FIG. 2C are cut out. The two laser pulses LP13 used in the processing step of reaching the bottom surface copper layer 63 of the recess 65 shown in FIG. 2D are cut out from the subsequent original laser pulse LO3.

  Since the original laser pulse LO2 that cuts out the laser pulse LP12 and the original laser pulse LO3 that cuts out the laser pulse LP13 are different, the pulse width of the laser pulse LP13 can be made different from the pulse width of the laser pulse LP12. Therefore, similar to the embodiment shown in FIG. 3A, the damage given to the bottom surface copper layer 63 can be reduced.

  However, in the example shown in FIG. 3C, three original laser pulses LO1, LO2, LO3 are required to form one blind via hole. Therefore, compared with the embodiment shown in FIG. 3A, the processing time becomes longer and the energy utilization efficiency of the laser beam is reduced.

  By using the laser pulse cutting device according to the embodiment, it is possible to reduce the damage given to the bottom surface copper layer 63 without prolonging the processing time.

  Next, the laser irradiation conditions of the laser processing method according to the embodiment will be described. The pulse width of the original laser pulses LO1 and LO2 (FIG. 3A) output by the laser light source 10 (FIG. 1), the time width from the rising time of the original laser pulse to the time of cutting out the first laser pulse toward the first machining path MP1 The time width from the rising time of the original laser pulse to the time of cutting out the first laser pulse toward the second machining path MP2 is set in advance.

  The control parameters that determine the irradiation conditions when processing the surface copper layer 62 include the pulse widths of the laser pulses LP11 and LP12 (FIG. 3A). The processing of the resin layer 61 is switched between two control modes, that is, a control mode in which the recess 65 is dug forward (FIG. 2C) and a control mode in which the recess 65 reaches the bottom copper layer 63 (FIG. 2D). Executed by. Therefore, it is necessary to set the irradiation conditions of these two control modes as the irradiation conditions when processing the resin layer 61. Each control mode is defined by control parameters including the pulse width of the laser pulse cut out to the machining path, the number of laser pulses, and the time width (interval) between the laser pulses.

  The control device 55 (FIG. 1) displays on the display device 56 image information (dialog) prompting the input of control parameters when these irradiation conditions are not set or when the operator performs an operation to change the irradiation conditions. Display it. Further, a "confirm button" and a "return button" are displayed. When the operator selects the "return button", the control device 55 displays the screen before displaying the dialog, for example, the main menu screen.

  FIG. 4 is a diagram showing an example of a dialog displayed on the display device 56. The controller 55, together with the message “Please enter the irradiation conditions.”, The pulse width when processing the surface copper layer 62, the pulse width for each control mode when processing the resin layer 61, the number of pulses, And the image for inputting the interval is displayed in a table format. Since the number of pulses for processing the surface copper layer 62 is one, it is not necessary to input the number of pulses and the interval for processing the surface copper layer 62. When the operator operates the input device 57 to input the values of these control parameters and selects the “confirm button”, the control device 55 acquires the values of these control parameters from the input device 57 and stores them in the storage device. Remember. When the control parameter is set, the controller 55 controls the beam deflector 20 according to the set control parameter.

  The operator can easily input the necessary control parameters while looking at the dialog shown in FIG.

  In the above embodiment, the controller 55 controls the beam deflector 20 by switching from one of the two control modes to the other within the pulse width of one original laser pulse, but it is selected from three or more control modes. The beam deflector 20 may be controlled in the one control mode. In this case, the controller 55 has a function of switching the control mode a plurality of times within the pulse width of one original laser pulse. This makes it possible to finely adjust the laser irradiation conditions.

  In the above-described embodiment, the printed board 60 (FIG. 2A) having the three-layer structure including the front surface copper layer 62, the resin layer 61, and the bottom surface copper layer 63 is the object to be processed. However, the object to be processed having other structures is a blind via hole. It is also possible to use the laser pulse slicing device according to the above-mentioned embodiment for the laser processing for forming. For example, it is also possible to use the laser pulse cutting device according to the embodiment for laser processing for forming a blind via hole reaching the inner copper layer on a multilayer printed board having a surface copper layer and a plurality of inner copper layers.

  In the above-described example, the blind via hole that penetrates both the surface copper layer 62 and the resin layer 61 is formed in the state where the opening is not formed in the surface copper layer 62. Such a method for forming via holes is called "direct processing". The laser pulse slicing apparatus according to the above-described embodiment is applicable to the laser processing in which the via hole is already formed in the surface copper layer and the concave portion is formed only in the resin layer thereunder. Such a via hole forming method is called "conformal processing". When performing conformal processing, the processing step using the laser pulse LP11 (FIG. 2B) is omitted, and the processing step using the laser pulse LP12 (FIG. 2C) and the processing step using the laser pulse LP13 (FIG. 2D). You can execute

  Although an acousto-optic deflector is used as the beam deflector 20 in the above embodiment, the traveling direction of the laser beam may be changed by using an electro-optic modulator (EOM) and a polarization beam splitter. Further, in the above embodiment, the beam deflector 20 has the function of directing the incident laser beam to the two processing paths, but a beam deflector having the function of directing only one processing path is used. Good.

  Next, a laser processing method according to another embodiment will be described with reference to FIGS. 5A to 8B. The laser pulse cutting device and the laser processing device used in this laser processing method are the same as those shown in FIG.

  Hereinafter, description of the configuration common to the embodiment shown in FIGS. 1 to 4 will be omitted. Although blind via holes are formed in the printed circuit board 60 in the embodiments shown in FIGS. 1 to 4, in the present embodiment, laser pulses are incident on the printed circuit board 60 from both sides to form through holes.

  5A to 5E are cross-sectional views of the printed circuit board 60 before, during and after processing when forming a through hole by the laser processing method according to the present embodiment.

  As shown in FIG. 5A, a printed circuit board 60 having a through hole has a three-layer structure in which a front surface copper layer 62, a resin layer 61, and a bottom surface copper layer 63 are laminated.

  As shown in FIG. 5B, a laser pulse LP31 is incident on the surface copper layer 62 to form a recess 70 penetrating the surface copper layer 62. The shape of the vertical cross section of the recess 70 is substantially trapezoidal. Further, as shown in FIG. 5C, the recess 70 is dug forward by making a plurality of laser pulses LP32 incident on the bottom surface of the recess 70. When the injection of the plurality of laser pulses LP32 is completed, the recess 70 reaches almost the middle point in the thickness direction of the resin layer 61. The pulse width of each laser pulse LP32 is shorter than the pulse width of the laser pulse LP31 (FIG. 5B). As a result, the pulse energy of each laser pulse LP32 becomes smaller than the pulse energy of the laser pulse LP31.

  When the irradiation of the laser pulse LP32 is completed, the front and back of the printed circuit board 60 are reversed. Thereafter, as shown in FIG. 5D, a laser pulse LP41 is made incident on the bottom surface copper layer 63 to form a recess 71 penetrating the bottom surface copper layer 63. The laser pulse LP41 is incident on the position corresponding to the position where the recess 70 is formed. At this point, the recess 71 does not reach the bottom surface of the recess 70 formed from the surface copper layer 62 side.

  As shown in FIG. 5D, the recess 71 is dug down by making a plurality of laser pulses LP42 incident on the bottom surface of the recess 71. As a result, the recess 70 formed from the front side and the recess 71 formed from the back side are combined to form the through hole 72. Since each of the recesses 70 and the recesses 71 has a trapezoidal vertical cross section, the through hole 72 has the smallest inner diameter at the substantially central portion in the thickness direction.

  Next, referring to FIG. 6, the variation in the inner diameter of the through hole 72 (FIG. 5E) in the central portion in the thickness direction and the pulse numbers of the laser pulse LP32 (FIG. 5C) and the laser pulse LP42 (FIG. 5E) are shown. The relationship will be described.

  FIG. 6 is a graph showing the relationship between the pulse number of the laser pulse LP32 (FIG. 5C) and the laser pulse LP42 (FIG. 5E) and the variation in the inner diameter of the through hole 72 (FIG. 5E) in the central portion in the thickness direction. . A plurality of through holes 72 were formed under the condition that the pulse numbers of the laser pulse LP32 and the laser pulse LP42 were different, and the hole diameter at the center of the through hole 72 was measured. The horizontal axis represents the pulse number of each of the laser pulse LP32 and the laser pulse LP42, and the vertical axis represents the peak-to-peak value of the inner diameter of the through hole 72 in the central portion in the unit of “μm”.

  The number of laser pulses LP32 processed from the front side is the same as the number of laser pulses LP42 processed from the back side. The pulse widths of the laser pulse LP32 and the laser pulse LP42 are set so that the total value of the pulse energy of the plurality of laser pulses LP32 and the total value of the pulse energy of the plurality of laser pulses LP42 are optimized.

  It can be seen that increasing the pulse numbers of the laser pulse LP32 and the laser pulse LP42 reduces the variation in the hole diameter at the center of the through hole 72. As can be seen from the results of this experiment, in order to reduce the variation in the hole diameter at the central portion of the through hole 72, the laser pulse LP32 (FIG. 5C) and the laser pulse LP42 (for digging the concave portions 70 and 71 of the resin layer 61). It is preferable to increase the number of pulses in FIG. 5E).

  FIG. 7 is a graph showing an example of the waveform of a laser pulse when forming a through hole by the method according to this embodiment.

  A laser pulse LP31 (FIG. 5B) for processing the surface copper layer 62 of the printed circuit board 60 arranged in the first processing path MP1 is cut out from the original laser pulse LO10 and a laser pulse LP32 (for processing the resin layer 61 from the front side is formed. FIG. 5C) is cut out from the original laser pulse LO11. A laser pulse LP41 (FIG. 5D) for processing the bottom surface copper layer 63 is cut out from the original laser pulse LO20, and a laser pulse LP42 (FIG. 5E) for processing the resin layer 61 from the back side is cut out from the original laser pulse LO21.

  A laser pulse cut out from the latter half of each of the original laser pulses LO10, LO11, LO20, and LO21 is used for processing the printed circuit board 60 arranged on the second processing path MP2.

  FIG. 8A is a graph showing an example of a pulse train of a plurality of laser pulses LP32. The upper graph shows an example in which the pulse widths of the six laser pulses LP32 are all 0.5 μs. The middle graph shows an example in which the pulse width of the five laser pulses LP32 is 0.5 μs and the pulse width of the remaining one laser pulse LP32 is 0.4 μs. The lower graph shows an example in which the pulse width of the four laser pulses LP32 is 0.5 μs and the pulse width of the remaining two laser pulses LP32 is 0.4 μs. Hereinafter, an example in which the pulse width of each laser pulse LP32 can be adjusted at 0.1 μs intervals will be described.

  Next, the excellent effect of this embodiment will be described in comparison with the comparative example shown in FIG. 8B. The laser pulse cutting device used in the laser processing method according to the comparative example cannot cut a plurality of laser pulses having different pulse widths from one original laser pulse.

  FIG. 8B is a graph showing an example of the waveform of a laser pulse when the laser processing method according to the comparative example is performed. In the comparative example, the pulse widths of the plurality of laser pulses LP32 cannot be changed within one original laser pulse LO11. The upper, middle, and lower graphs of FIG. 8B show examples in which the pulse widths of the six laser pulses LP32 are all 0.5 μs, 0.4 μs, and 0.3 μs, respectively.

  The total pulse widths of the pulse trains shown in the upper, middle, and lower graphs of FIG. 8B are 3.0 μs, 2.4 μs, and 1.8 μs, respectively. As described above, when the laser pulse cutting device according to the comparative example is used, the total value of the pulse widths is only 0.6 μs with the condition that the number of pulses of the laser pulse LP32 is six. I can't adjust. For example, even if it is desirable to set the total pulse width to 2.7 μs in order to match the hole diameter at the center of the through hole with the target value, the total pulse width can be matched to that value. Inevitably, the processing must be performed under the condition that the total value of the pulse width is 3.0 μs or 2.4 μs.

  On the other hand, when the laser pulse cutting device according to the present embodiment is used, as shown in FIG. 8A, the total value of pulse widths can be adjusted in 0.1 μs steps. The total pulse width value corresponds to the total pulse energy value. Therefore, in this embodiment, it is possible to adjust the total value of the pulse energy with a finer step size than in the comparative example. As a result, it becomes possible to perform processing under optimum conditions for making the hole diameter at the center of the through hole match the target value.

  Needless to say, each of the above-described embodiments is merely an example, and partial replacement or combination of the configurations shown in different embodiments is possible. The same effects by the same configurations of the plurality of embodiments will not be sequentially described for each embodiment. Furthermore, the invention is not limited to the embodiments described above. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

Reference Signs List 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 cutout 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 control device 56 display device 57 input device 60 printed circuit board 61 resin layer 62 surface copper layer 63 bottom copper layer 65 recesses 70, 71 recesses 72 Through hole

Claims (5)

A beam deflector that directs an incident laser beam to a processing path toward a processing object according to a command from the outside,
A controller having a function of cutting out a plurality of laser pulses having different pulse widths and pulse energies from one original laser pulse incident on the beam deflector toward the processing path by giving a command to the beam deflector. Laser pulse cutting device having.   The control device controls the beam deflector in one of the control modes selected from a plurality of control modes, and in each of the control modes, a pulse width cut out from the original laser pulse and the number of laser pulses cut out. , And an interval between laser pulses is set, and the laser pulse cutting device according to claim 1, which has a function of switching the control mode within a pulse width of one of the original laser pulses. A control device for controlling a beam deflector, which directs a laser beam from an incident laser beam to a processing path toward a processing object, in one of the control modes selected from a plurality of control modes,
A display device for displaying an image under the control of the control device,
And an input device,
Each of the control modes is a control parameter including a pulse width of a laser pulse cut out from the original laser pulse incident on the beam deflector toward the processing path, the number of laser pulses cut out, and an interval between laser pulses. Stipulated,
The laser pulse cutting device, wherein the control device causes the display device to display image information prompting the input of the control parameter, and acquires the control parameter input from the input device.   A laser processing method for laser processing an object to be processed by cutting out a plurality of laser pulses having different pulse widths and pulse energies from one original laser pulse toward a processing path and making the laser pulses incident on the object to be processed.   The hole is formed in the object by reducing the pulse energy by shortening the pulse width of the laser pulse to be cut out in the middle of a period in which a plurality of laser pulses are cut out from one original laser pulse. The laser processing method described.

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