Laser processing method and laser processing apparatus

Abstract

This disclosure relates to a laser processing method and a laser processing apparatus. [Solution] The laser processing method includes a first step of processing a pilot hole by irradiating a fluororesin with pulsed laser light of ultraviolet wavelength so as to draw a first closed orbit, and a second step of processing a hole by irradiating the fluororesin with the pilot hole processed with pulsed laser light so as to draw a second closed orbit that is similar in shape to the first closed orbit and larger than the first closed orbit.

Description

Technical Field

[0001] The present disclosure relates to a laser processing method and a laser processing apparatus.

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, with the miniaturization and high integration of semiconductor integrated circuits, improvement of resolution has been demanded. For this reason, the shortening of the wavelength of light emitted from an exposure light source has been promoted. For example, as a gas laser apparatus for exposure, a KrF excimer laser apparatus that outputs laser light with a wavelength of about 248 nm and an ArF excimer laser apparatus that outputs laser light with a wavelength of about 193 nm are used.

[0003] Further, excimer laser light has a pulse width of about several 10 ns, and since the wavelengths are 248 nm and 193 nm, respectively, which are short, it may be used for direct processing of polymer materials, glass materials, etc. Chemical bonds in polymer materials can be broken by excimer laser light having photon energy higher than the bond energy. Therefore, non-thermal processing of polymer materials is possible with excimer laser light, and it is known that the processing shape becomes neat. Also, since glass, ceramics, etc. have a high absorption rate for excimer laser light, it is known that even materials that are difficult to process with visible and infrared laser light can be processed with excimer laser light.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] A laser processing method relating to one aspect of this disclosure includes a first step of processing a pilot hole in a fluororesin by irradiating it with pulsed laser light of ultraviolet wavelength so as to draw a first closed orbit, and a second step of processing a hole in the fluororesin from which the pilot hole has been processed by irradiating it with pulsed laser light so as to draw a second closed orbit that is similar in shape to the first closed orbit and larger than the first closed orbit.

[0006] A laser processing apparatus relating to another aspect of the present disclosure comprises a focusing lens for focusing pulsed laser light of ultraviolet wavelength onto a workpiece, which is a fluororesin; a moving device for moving the irradiation position of the pulsed laser light onto the fluororesin; and a processor for controlling the moving device, wherein the processor performs a first control for processing a pilot hole by irradiating the fluororesin with pulsed laser light so as to trace a first closed orbit; and a second control for processing a hole by irradiating the fluororesin with the pilot hole processed with pulsed laser light so as to trace a second closed orbit that is similar in shape to the first closed orbit and larger than the first closed orbit. [Brief explanation of the drawing]

[0007] Some embodiments of this disclosure are described below, merely as examples, with reference to the accompanying drawings. [Figure 1] Figure 1 is a schematic diagram showing the configuration of a laser processing system related to a comparative example. [Figure 2] Figure 2 shows an example of a closed trajectory of pulsed laser light on the workpiece surface by the laser processing method according to the comparative example. [Figure 3] Figure 3 is a schematic diagram illustrating the scattered light and heat generated when drilling holes in a workpiece using pulsed laser light in a closed orbit. [Figure 4] Figure 4 is a schematic diagram showing a cross-section of a hole processed by the laser processing method according to the comparative example. [Figure 5] Figure 5 is a schematic diagram showing the configuration of a laser processing system including a laser processing apparatus according to Embodiment 1. [Figure 6] Figure 6 is a top view of the dust collection head. [Figure 7]Figure 7 shows an example of the trajectory of pulsed laser light on the surface of a workpiece by the laser processing method according to Embodiment 1. [Figure 8] Figure 8 is a cross-sectional view showing an example of a pilot hole obtained by the first step. [Figure 9] Figure 9 is a cross-sectional view showing an example of a hole obtained by the second step. Embodiment

[0008] -table of contents- 1. Overview of the laser processing system related to the comparative example 1.1 Configuration 1.2 Operation 1.3 Challenges 2. Embodiment 1 2.1 Configuration 2.2 Operation 2.3 Action and Effects 2.4 Examples of specific hole machining 2.5 Processing Conditions 2.6 Examples of uses for workpieces with holes machined into them 3. Others

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are examples of the disclosure and are not intended to limit the scope of this disclosure. Furthermore, not all configurations and operations described in each embodiment are necessarily essential to the configurations and operations of this disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] 1. Overview of the laser processing system related to the comparative example 1.1 Configuration Figure 1 is a schematic diagram showing the configuration of a laser processing system 10 relating to a comparative example. The comparative example in this disclosure is a form inferred by analogy from the general art by the applicant and is not a known example acknowledged by the applicant.

[0011] The laser processing system 10 includes a laser device 12 and a laser processing device 14. The laser device 12 is a laser device that outputs pulsed laser light with an ultraviolet wavelength. For example, the laser device 12 may be an excimer laser device. The wavelength of the pulsed laser light output by the laser device 12 may be, for example, 158 nm or more and 246 nm or less. Note that a fluorine excimer laser device can output pulsed laser light with a wavelength of 158 nm.

[0012] The laser processing device 14 includes a processing processor 100, high-reflection mirrors 111 and 112, a galvanometer scanner 120, a condenser lens 130, a table 140, an XYZ stage 150, and a frame 154.

[0013] The high-reflection mirror 111 is arranged to reflect the pulsed laser light output from the laser device 12 and make it incident on the high-reflection mirror 112. The high-reflection mirror 112 is arranged to reflect the pulsed laser light reflected by the high-reflection mirror 111 toward the galvanometer scanner 120.

[0014] The galvanometer scanner 120 includes an X-direction galvanometer scanner 121 that scans the pulsed laser light in the X direction and a Y-direction galvanometer scanner 122 that scans the pulsed laser light in the Y direction. The X-direction galvanometer scanner 121 and the Y-direction galvanometer scanner 122 are controlled to operate in synchronization with the timing of the output of the pulsed laser light from the laser device 12. In FIG. 1, the direction parallel to the direction in which the pulsed laser light travels from the condenser lens 130 toward the workpiece 20 is defined as the Z direction. Also, the X direction and the Y direction are perpendicular to the Z direction and perpendicular to each other. The coordinate axes in the following drawings are the same as those in FIG. 1.

[0015] The condenser lens 130 condenses the pulsed laser light output from the galvanometer scanner 120. The condenser lens 130 may be any of a spherical lens, an aspherical lens, or an F-θ lens. The spot size of the condensing point may be, for example, about 200 μm to 300 μm.

[0016] The XYZ stage 150 is a stage with an actuator that can move in three mutually perpendicular axes in the X, Y, and Z directions. The XYZ stage 150 is fixed to the frame 154, and the table 140 is disposed on the XYZ stage 150. The table 140 is a mounting table for mounting the workpiece 20.

[0017] The workpiece 20 is set at a position (focus position) on the table 140 where the pulsed laser beam is focused by the condenser lens 130. The workpiece 20 is a fluororesin, for example, polytetrafluoroethylene (PTFE). The workpiece 20 is not limited to PTFE and may be perfluoroalkoxy alkane (PFA), perfluoroethylene propene copolymer (FEP), polyvinylidene fluoride (PVDF), or the like.

[0018] The processing processor 100 controls the operations of the laser device 12, the galvanometer scanner 120, and the XYZ stage 150. The processing processor 100 may be physically configured in the form of hardware to execute various processes included in the present disclosure. For example, the processing processor 100 may be a computer including a memory storing a control program that defines various processes and a processing device that executes the control program. The control program may be stored in one memory or may be divided and stored in a plurality of memories that are physically separated, and various processes may be defined by the control program as an aggregate thereof. The processing device may be a general-purpose processing device such as a CPU (Central Processing Unit) or a special-purpose processing device such as a GPU (Graphics Processing Unit).

[0019] Furthermore, the machining processor 100 may be programmed in software form to perform the various processes included in this disclosure. For example, the machining processor 100 may have functions for performing the various processes implemented in a dedicated device such as an ASIC (Application Specific Integrated Circuit) or a programmable device such as an FPGA (Field Programmable Gate Array).

[0020] The various processes included in this disclosure may be performed by one computer, one dedicated device, or one programmable device, or by the cooperation of multiple computers, multiple dedicated devices, or multiple programmable devices located physically separately. The various processes may be performed by at least two combinations of one or more computers, one or more dedicated devices, and one or more programmable devices.

[0021] 1.2 Operation The pulsed laser light output from the laser device 12 is reflected by the high-reflectivity mirrors 111 and 112 and incident on the galvanometer scanner 120. The processing processor 100 moves the workpiece 20 using the XYZ stage 150 so that the processing point on the workpiece 20 is at the focus position. The focus position of the focusing lens 130 is near the surface of the workpiece 20. The focusing lens 130 is selected to have a focal length such that the Rayleigh length at the focal point is between 1 / 10 and 10 times the thickness of the workpiece 20.

[0022] When drilling holes in the workpiece 20, the machining processor 100 instructs the galvanoscanner 120 to trace a closed orbit on the surface of the workpiece 20 at a predetermined scanning speed using pulsed laser light. The closed orbit may be, for example, a circular orbit as shown in Figure 2, an elliptical orbit, or an oval orbit that combines a circular arc and a straight line.

[0023] Figure 2 shows an example of a closed orbit C of pulsed laser light on the surface of a workpiece 20 using a laser processing method according to a comparative example. The closed orbit C shown in Figure 2 is a circular orbit with diameter D. Figure 3 is a schematic explanatory diagram showing the scattered light and heat generated when a hole is drilled in the workpiece 20 by irradiating it with pulsed laser light in a closed orbit C.

[0024] The galvanoscanner 120 receives commands from the processing processor 100 and controls the X-direction galvanoscanner 121 and the Y-direction galvanoscanner 122 so that the pulsed laser light traces a circular orbit on the workpiece surface 20 at a predetermined scanning speed.

[0025] The processing processor 100 outputs a control signal to the laser device 12 that turns the output of the pulsed laser beam on and off in accordance with the operation of the galvanometer scanner 120. The laser device 12 outputs pulsed laser beam of a predetermined power in accordance with the control signal. As a result, the pulsed laser beam is irradiated onto the workpiece 20, and hole drilling is performed. The processing processor 100 controls the galvanometer scanner 120 and the laser device 12 so that the pulsed laser beam circles the closed orbit C multiple times. Approximately 40 pulses of pulsed laser beam may be irradiated per rotation of the closed orbit C. After hole drilling is completed, the processing processor 100 moves the workpiece 20 using the XYZ stage 150 so that the irradiation position of the pulsed laser beam is at the position of the next processing point.

[0026] 1.3 Challenges Figure 4 schematically shows a cross-section of a hole processed by the laser processing method according to the comparative example. The scattered light and heat generated by the pulsed laser beam irradiated onto the workpiece 20 process the workpiece 20 near the irradiated area. As a result, as shown in Figure 4, when a hole is processed in a closed orbit C, the diameter of the hole on the side where the pulsed laser beam is incident (front surface) is larger than the diameter of the hole on the opposite side (back surface). In other words, the processed hole has a taper, with a larger processed diameter on the side where the pulsed laser beam is incident and a smaller processed diameter on the opposite side.

[0027] For example, when drilling a hole in a 2mm thick PTFE workpiece 20 with an input power of 8W, a scan speed of 200mm / sec, a circular orbit diameter D of φ0.8mm, and 500 orbital revolutions, the diameter of the hole on the front side of the workpiece 20 will be φ1.6mm, and the diameter of the hole on the back side will be φ0.8mm. The input power refers to the power of the pulsed laser beam irradiated onto the workpiece 20.

[0028] In this case, the tapered region T is the area in the workpiece 20 where the hole diameter changes in the thickness direction of the workpiece 20, from the edge of the hole on the front side to the edge of the hole on the back side of the workpiece 20. The larger the difference between the hole diameter on the front side and the hole diameter on the back side of the workpiece 20 in the machined hole, the larger the tapered region T becomes.

[0029] In hole machining of fluoropolymers such as PTFE, there is a requirement to machine holes with a small taper region T.

[0030] 2. Embodiment 1 2.1 Configuration Figure 5 is a schematic diagram showing the configuration of a laser processing system including a laser processing apparatus 14A according to Embodiment 1. The differences between the configuration shown in Figure 5 and that in Figure 1 will be explained. The laser processing apparatus 14A according to Embodiment 1 includes a purging mechanism 170 for purging the light propagation section 126, which includes high-reflection mirrors 111, 112 and a galvanoscanner 120, with an inert gas, and a dust collection mechanism 180 for protecting the focusing lens 130. The high-reflection mirrors 111, 112 and the galvanoscanner 120 are examples of the "optical system" in this disclosure.

[0031] The inert gas for the purging mechanism 170 may be nitrogen (N2) gas. The N2 gas used for purging may be supplied from the pulsed laser output section of the laser device 12, or N2 gas may be introduced from outside the laser processing device 14A, or both may be used. A lens (not shown) located at the pulsed laser output section may be used as a sealing section for the purged area.

[0032] The purging mechanism 170 shown in Figure 5 includes a gas inlet 172 for introducing N2 gas from the outside into a housing 171 that covers the area of ​​the light propagation section 126, and a gas outlet 173 for discharging N2 gas from inside the housing 171. The gas inlet 172 is located near the output section of the pulsed laser beam of the laser device 12, and the gas outlet 173 is located near the focusing lens 130. The N2 gas supplied into the housing 171 from at least one of the output section of the pulsed laser beam of the laser device 12 and the gas inlet 172 flows to the high-reflection mirrors 111, 112, the galvanometer scanner 120, and the focusing lens 130, and is discharged from the gas outlet 173.

[0033] The dust collection mechanism 180 includes a dust collector 182 and a dust collection head 184. Figure 6 is a top view of the dust collection head 184. The dust collection head 184 has a space 185 in the center through which light can be introduced, and an annular cover 186 that forms an air passage surrounding this light-introducing space 185 is provided with two or more suction ports 187A and 187B. Each of the suction ports 187A and 187B is connected to the dust collector 182 via pipes 188A and 188B.

[0034] The dust collection head 184 can generate a spiral airflow by drawing in air through the suction ports 187A and 187B. This generated airflow moves plumes and dust generated during processing to the outer periphery, which has the effect of suppressing the reduction in processing efficiency caused by plumes and dust obstructing the pulsed laser light, and also has the effect of suppressing damage to the lens and a decrease in transmittance caused by plumes and dust adhering to the focusing lens 130.

[0035] Furthermore, the generated airflow causes the ozone produced by the incident pulsed laser light to move from the pulsed laser light irradiation area to the outer periphery, so that the pulsed laser light is not absorbed by the ozone, enabling efficient processing in an atmospheric environment. The other configurations are the same as those of the laser processing system 10.

[0036] 2.2 Operation Figure 7 shows an example of the trajectory of pulsed laser light on the surface of a workpiece 20 by the laser processing method according to Embodiment 1. The laser processing method when drilling a hole in a workpiece 20 using the laser processing apparatus 14A according to Embodiment 1 includes the steps of: drilling a pilot hole by irradiating the workpiece 20 with pulsed laser light so as to trace a first closed trajectory C1; and drilling a hole in the workpiece 20 from which the pilot hole has been drilled by irradiating it with pulsed laser light so as to trace a second closed trajectory C2 that is similar in shape to the first closed trajectory C1 and larger than the first closed trajectory C1. The second closed trajectory C2 may be a trajectory that coincides with the shape of the hole that is the processing target (purpose). "Coincidence" is not limited to a perfect coincidence, but includes the concept of approximate coincidence, which is within a range that is practically acceptable.

[0037] The process of machining a pilot hole is an example of the "first process" in this disclosure, and the process of machining a hole that is closer to the target hole shape than the pilot hole after machining the pilot hole is an example of the "second process" in this disclosure. Furthermore, the control for machining the pilot hole is an example of the "first control" in this disclosure, and the control for machining a hole that is closer to the target hole shape than the pilot hole after machining the pilot hole is an example of the "second control" in this disclosure. The laser machining method according to Embodiment 1, which includes the first and second processes, is carried out in an atmospheric environment without using an assist gas.

[0038] Figure 8 is a cross-sectional view showing an example of a pilot hole obtained in the first step. Figure 9 is a cross-sectional view showing an example of a hole obtained in the second step.

[0039] When a hole is drilled in a workpiece 20 using the laser processing apparatus 14A according to Embodiment 1, the processing processor 100 instructs the galvanoscanner 120 to trace a first closed orbit C1 on the surface of the workpiece 20 at a predetermined scanning speed using pulsed laser light. The first closed orbit C1 may be a circular orbit, an elliptical or oval orbit, as shown in Figure 7, for example.

[0040] The galvanometer scanner 120 receives commands from the processing processor 100 and controls the X-direction galvanometer scanner 121 and the Y-direction galvanometer scanner 122 so that the pulsed laser light draws a first closed orbit C1 on the surface of the workpiece 20 at a predetermined scan speed.

[0041] The processing processor 100 outputs a control signal for performing On-Off control of the output of the pulsed laser light in accordance with the operation of the galvanometer scanner 120 to the laser device 12. The laser device 12 outputs pulsed laser light of a predetermined power in accordance with the control signal. Thereby, a pilot hole is machined in the workpiece 20 (see FIG. 8). The pilot hole does not have to penetrate, but it is desirable for it to penetrate. The penetrated pilot hole is an example of the "through hole" in the present disclosure.

[0042] Thereafter, as shown in FIG. 7, the processing processor 100 commands the galvanometer scanner 120 so that the pulsed laser light draws a second closed orbit C2 that is similar to the first closed orbit C1 and larger than the first closed orbit C1 on the surface of the workpiece 20 at a predetermined scan speed. The second closed orbit C2 may be a circular orbit, an elliptical orbit, or an oval orbit.

[0043] When the first closed orbit C1 is a circular orbit with a diameter D1, the second closed orbit C2 is a circular orbit with a diameter D2, and the diameter D2 is larger than the diameter D1 (D1 < D2). It is desirable that the center of the first closed orbit C1 and the center of the second closed orbit C2 coincide. FIG. 7 shows an example in which the first closed orbit C1 and the second closed orbit C2 are concentric circles. Note that the center of a closed orbit other than a circular orbit may be, for example, the centroid of a figure having the closed orbit as a contour line. It is desirable that the orbital distance between the first closed orbit C1 and the second closed orbit C2 is constant over the entire circumference of the closed orbit.

[0044] Furthermore, the second closed orbital C2 is defined as a closed orbital drawn inside the region where the thickness of the workpiece 20 changed due to machining the pilot hole in the first closed orbital C1. That is, the region enclosed by the second closed orbital C2 is smaller than the region where the thickness of the workpiece 20 changed due to machining in the first closed orbital C1, and is contained within the region where the thickness of the workpiece 20 changed due to the first process.

[0045] The galvanoscanner 120 receives commands from the processing processor 100 and controls the X-direction galvanoscanner 121 and the Y-direction galvanoscanner 122 so that the pulsed laser light traces a second closed trajectory C2 on the workpiece surface 20 at a predetermined scanning speed.

[0046] The processing processor 100 outputs a control signal to the laser device 12 that switches the output of the pulsed laser beam on and off in accordance with the operation of the galvanometer scanner 120. The laser device 12 outputs pulsed laser beam of a predetermined power according to the control signal. This performs hole drilling.

[0047] When hole machining is complete, the machining processor 100 moves the workpiece 20 on the XYZ stage 150 so that the pulse laser beam is positioned at the next machining point. The machining processor 100 is an example of a “processor” in this disclosure. The galvanometer scanner 120 and the XYZ stage 150 are examples of “moving devices” in this disclosure.

[0048] Furthermore, in the laser processing apparatus 14A according to Embodiment 1, a process to reduce the thickness of the workpiece 20 may be performed in a region smaller than the region in which the thickness of the workpiece 20 changes due to laser irradiation in the second closed orbital C2, before the laser irradiation process in the second closed orbital C2 is performed.

[0049] In other words, between the step of machining a pilot hole in the first closed orbital C1 and the step of machining a hole of the desired shape in the second closed orbital C2 after machining the pilot hole, a step may be added in which pulsed laser light is irradiated in a third closed orbital to further reduce the thickness of the region whose thickness has changed due to the machining of the pilot hole (first step). In this case, the third closed orbital may be larger than the first closed orbital C1 and smaller than the second closed orbital C2. Similarly, between the step of reducing the thickness by irradiating with pulsed laser light in the third closed orbital and the step of machining the desired hole in the second closed orbital C2, a step may be added in which pulsed laser light is irradiated in a fourth closed orbital to further reduce the thickness of the region whose thickness has changed due to laser irradiation in the first closed orbital C1 and the third closed orbital. In this case, the fourth closed orbital may be larger than the third closed orbital and smaller than the second closed orbital C2. Thus, the laser processing method according to Embodiment 1 may process a pilot hole by gradually changing the size of the closed track, and finally process a hole with the desired processing shape.

[0050] 2.3 Action and Effects In the laser processing method according to Embodiment 1, when a pilot hole is pre-processed in the first closed orbital C1, hole processing in the second closed orbital C2 begins with a portion of the workpiece 20 already processed. Therefore, the processing time is shorter compared to the case where processing is performed in the second closed orbital C2 from the beginning.

[0051] Furthermore, if a pilot hole is pre-drilled, a space is created in the workpiece 20 for the pilot hole. As a result, the scattered light generated during hole drilling in the second closed orbital C2 hits the inner surface of the hole less often compared to when drilling in the second closed orbital C2 from the beginning.

[0052] These effects suppress the temperature rise at the drilling site. Furthermore, the amount of material removed by scattered light is also suppressed. As a result, it becomes possible to drill holes with a small taper region T.

[0053] 2.4 Examples of specific hole machining For example, when machining a pilot hole in 2mm thick PTFE with an input power of 8W, a scan speed of 400mm / sec, and a first closed orbit C1 with a diameter D1 of φ0.4mm and 800 rotations, if a second closed orbit C2 with an input power of 8W, a scan speed of 400mm / sec, and 500 rotations is performed, the hole on the surface of the PTFE irradiated with pulsed laser light will have a diameter of φ1.2mm, and the hole on the back side will have a diameter of φ0.8mm.

[0054] In the comparative example, the diameter of the hole processed by the laser processing method was φ1.6 mm on the side irradiated with pulsed laser light, but in the laser processing method according to Embodiment 1, it becomes smaller, at φ1.2 mm. Therefore, in Embodiment 1, when processing holes in PTFE by irradiation with pulsed laser light of ultraviolet wavelength, it is possible to laser process holes with a small tapered region T.

[0055] Furthermore, in the specific example described above, the laser processing method according to Embodiment 1 has a higher scan speed compared to the laser processing method according to the comparative example, and processing is performed at twice the scan speed (400 mm / sec) compared to the scan speed (200 mm / sec) of the comparative example. Therefore, the processing time using the laser processing method according to Embodiment 1 can be approximately the same as, or shorter than, the processing time using the laser processing method according to the comparative example.

[0056] Furthermore, in the laser processing apparatus 14A according to Embodiment 1, pulsed laser light is irradiated onto the workpiece 20 from one direction, and the processing of the pilot hole and the subsequent hole is performed in succession. Since the next hole is processed after the previous hole has been processed, there is no need to turn the workpiece 20 over, and the processing time can be shortened.

[0057] Furthermore, the laser processing method according to Embodiment 1 has the effect of suppressing the thermal effects that occur when processing the PTFE workpiece 20, since the processing time can be shortened.

[0058] 2.5 Processing Conditions [1] Scan speed The conditions for the scan speeds that trace the first closed orbit C1 and the scan speeds that trace the second closed orbit C2 may be appropriately determined based on the thickness of the workpiece 20, the power of the pulsed laser beam, the desired hole shape, the size of the allowable taper region T, etc. The scan speeds that trace the first closed orbit C1 and the scan speeds that trace the second closed orbit C2 may be equal or different. For the first closed orbit C1, the conditions of a scan speed of 400 mm / sec and 800 rotations are examples of experimentally determined conditions that enable the machining of a through hole as a pilot hole. Similarly, for the second closed orbit C2, the conditions of a scan speed of 400 mm / sec and 500 rotations are examples of experimentally determined conditions that enable the machining of the desired hole.

[0059] [2] Number of laps on a closed track The number of times the laser orbits the first closed orbital C1 when machining the pilot hole, and the number of times it orbits the second closed orbital C2 after machining the pilot hole, may be appropriately determined depending on the thickness of the workpiece 20, the power of the pulsed laser beam, the desired hole shape, the size of the allowable taper region T, and so on.

[0060] The number of orbits of the first closed orbit C1 and the number of orbits of the second closed orbit C2 may each be multiple. For example, the number of orbits of the second closed orbit C2 may be less than the number of orbits of the first closed orbit C1.

[0061] 2.6 Examples of uses for workpieces with holes machined into them The workpiece 20 with the holes processed may be used, for example, as a braille device. The braille device may be, for example, about 50 cm 2 A PTFE sheet having a certain area requires approximately 100 densely packed holes. By using the laser processing apparatus 14A according to Embodiment 1, multiple holes can be processed in a PTFE sheet. The laser processing method according to Embodiment 1 makes it possible to process multiple holes where the distance between adjacent holes is, for example, 0.1 mm to 3.0 mm.

[0062] 3. Others The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. It will also be apparent to those skilled in the art that the embodiments of this disclosure can be used in combination.

[0063] Terms used throughout this specification and the claims should be interpreted as "non-limiting" unless otherwise specified. For example, terms such as "includes," "have," "equip," and "possess" should be interpreted as "not excluding the existence of components other than those described." Also, the modifier "one" should be interpreted as "at least one" or "one or more." Furthermore, the term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." In addition, it should be interpreted as including combinations of these with anything other than "A," "B," and "C."

Claims

1. The first step involves irradiating the fluororesin with pulsed ultraviolet laser light to create a first closed orbit to process a pilot hole, A second step involves irradiating the fluororesin from which the pilot hole has been processed with pulsed laser light to create a second closed orbital that is similar in shape to the first closed orbital and larger than the first closed orbital, A laser processing method that includes [specific type of laser processing].

2. A laser processing method according to claim 1, The second closed orbital is included in the region in which the thickness of the fluororesin has changed by the first step. Laser processing method.

3. A laser processing method according to claim 1, The ultraviolet wavelength is between 158 nm and 246 nm. Laser processing method.

4. A laser processing method according to claim 1, The aforementioned pilot hole is a through hole. Laser processing method.

5. A laser processing method according to claim 1, The first closed orbit is a circular orbit. Laser processing method.

6. A laser processing method according to claim 1, The first and second steps are carried out in an atmospheric environment without the use of an assist gas. Laser processing method.

7. A laser processing method according to claim 1, The second closed track corresponds to the shape of the hole to be machined. Laser processing method.

8. A laser processing method according to claim 1, The first step involves irradiating the inside of the region where the thickness of the fluororesin has changed with the pulsed laser light so as to trace the second closed orbit, thereby processing the hole. Laser processing method.

9. A laser processing method according to claim 1, The center of the first closed orbit and the center of the second closed orbit coincide. Laser processing method.

10. A laser processing method according to claim 1, The first step includes irradiating the fluororesin with the pulsed laser light such that it traces the first closed orbit multiple times. The second step includes irradiating the fluororesin with the pulsed laser light such that it traces the second closed orbit multiple times. Laser processing method.

11. A laser processing method according to claim 10, The number of times the second closed orbit is circled is less than the number of times the first closed orbit is circled. Laser processing method.

12. A laser processing method according to claim 1, The scan speed of the first closed orbit and the scan speed of the second closed orbit are equal. Laser processing method.

13. A focusing lens is used to concentrate pulsed laser light of ultraviolet wavelength onto the fluororesin workpiece, A moving device for moving the irradiation position of the pulsed laser light onto the fluororesin, The system comprises a processor that controls the aforementioned mobile device, The aforementioned processor, A first control method involves irradiating the fluororesin with the pulsed laser light to create a first closed orbit and process a pilot hole, A second control method for processing holes in the fluororesin from which the pilot hole has been processed by irradiating it with pulsed laser light such that it traces a second closed orbit that is similar in shape to the first closed orbit and larger than the first closed orbit; A laser processing device that performs this operation.

14. A laser processing apparatus according to claim 13, The system further includes a dust collection mechanism to protect the light-gathering lens. Laser processing equipment.

15. A laser processing apparatus according to claim 14, The dust collection mechanism includes a dust collection head that generates a spiral airflow and a dust collector connected to the dust collection head. Laser processing equipment.

16. A laser processing apparatus according to claim 13, The optical propagation section, which includes an optical system that guides the pulsed laser light to the focusing lens, further comprises a purging mechanism for flowing an inert gas through it. Laser processing equipment.

17. A laser processing apparatus according to claim 13, The aforementioned processor, The moving device is controlled to trace the second closed orbit within the region where the thickness of the fluororesin has changed due to the first control. Laser processing equipment.

18. A laser processing apparatus according to claim 13, The ultraviolet wavelength is between 158 nm and 246 nm. Laser processing equipment.

19. A laser processing apparatus according to claim 13, The aforementioned pilot hole is a through hole. Laser processing equipment.

20. A laser processing apparatus according to claim 13, The first closed orbital and the second closed orbital are concentric circles. Laser processing equipment.

Images