Laser processing method and laser processing apparatus

Abstract

This disclosure provides a laser processing method and a laser processing apparatus. The laser processing method includes: a first step of processing a pre-processed hole by irradiating a fluororesin with a pulsed laser of an ultraviolet wavelength in a manner that draws a first closed track; and a second step of processing a hole by irradiating a fluororesin with a pre-processed hole with a pulsed laser in a manner that draws a second closed track, the second closed track being similar in shape to the first closed track and larger than the first closed track.

Description

Technical Field

[0001] This disclosure relates to laser processing methods and laser processing apparatus. Background Technology

[0002] In recent years, with the miniaturization and high integration of semiconductor integrated circuits, there has been a growing demand for higher resolution in semiconductor exposure equipment. Therefore, efforts are underway to shorten the wavelength of light emitted from exposure light sources. For example, KrF excimer laser devices using lasers with an output wavelength of approximately 248 nm and ArF excimer laser devices using lasers with an output wavelength of approximately 193 nm are examples of gas laser devices used for exposure.

[0003] Furthermore, excimer lasers have pulse widths of approximately tens of ns and wavelengths as short as 248 nm and 193 nm, respectively, making them sometimes used for the direct processing of polymer materials, glass materials, and the like. Chemical bonds in polymer materials can be broken by excimer lasers, which possess photon energies higher than bond energies. Therefore, it is known that excimer lasers can be used for non-thermal processing of polymer materials, resulting in well-formed shapes. Additionally, glass, ceramics, and other materials are known to have high absorption rates for excimer lasers, allowing even materials that are difficult to process using visible and infrared lasers to be processed using excimer lasers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 1990-001374

[0007] Patent Document 2: Japanese Patent Application Publication No. 2007-237235 Summary of the Invention

[0008] One aspect of the laser processing method disclosed herein includes: a first step of processing a pre-machined hole by irradiating a fluororesin with a pulsed laser of an ultraviolet wavelength in a manner that draws a first closed track; and a second step of processing a hole by irradiating a fluororesin with a pre-machined hole with a pulsed laser in a manner that draws a second closed track, the second closed track being similar in shape to the first closed track and larger than the first closed track.

[0009] Another aspect of the laser processing apparatus disclosed herein includes: a focusing lens that focuses a pulsed laser of ultraviolet wavelength onto a fluoropolymer resin, which is a workpiece; a moving device that moves the position of the pulsed laser irradiation onto the fluoropolymer resin; and a processor that controls the moving device to perform: a first control to irradiate the fluoropolymer resin with the pulsed laser in a manner that draws a first closed track to process a pre-processed hole; and a second control to irradiate the fluoropolymer resin with the pre-processed hole onto the fluoropolymer resin in a manner that draws a second closed track, the second closed track being similar in shape to the first closed track and larger than the first closed track. Attached Figure Description

[0010] The following description, by way of example only, refers to the accompanying drawings to illustrate several embodiments of this disclosure.

[0011] Figure 1 This is a diagram that roughly illustrates the structure of the laser processing system of the comparative example.

[0012] Figure 2 This is a diagram illustrating an example of the closed trajectory of a pulsed laser on the surface of a workpiece in a laser processing method based on a comparative example.

[0013] Figure 3 This is a schematic diagram illustrating the scattered light and heat generated when a pulsed laser is irradiated in a closed orbit to perform hole machining on a workpiece.

[0014] Figure 4 This is a schematic diagram showing the cross-section of a hole processed by the laser processing method of the comparative example.

[0015] Figure 5 This is a diagram that schematically illustrates the structure of a laser processing system including the laser processing apparatus of Embodiment 1.

[0016] Figure 6 This is a top view of the dust collection head.

[0017] Figure 7 This is a diagram illustrating an example of the trajectory of a pulsed laser on the surface of a workpiece in the laser processing method based on Embodiment 1.

[0018] Figure 8 This is a cross-sectional view showing an example of a pre-machined hole obtained through the first process.

[0019] Figure 9 This is a cross-sectional view showing an example of a hole obtained through the second process. Detailed Implementation

[0020] -Table of contents-

[0021] 1. Overview of the comparative laser processing system

[0022] 1.1 Structure

[0023] 1.2 Actions

[0024] 1.3 Research Topic

[0025] 2. Implementation Method 1

[0026] 2.1 Structure

[0027] 2.2 Actions

[0028] 2.3 Functions and Effects

[0029] 2.4 Specific examples of hole machining

[0030] 2.5 Regarding processing conditions

[0031] 2.6 Examples of applications for machining workpieces with holes

[0032] 3. Other

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and operations described in each embodiment are not necessarily all necessary as structures and operations of the present disclosure. Furthermore, the same reference numerals are used to denote the same constituent elements, and repeated descriptions are omitted.

[0034] 1. Overview of the comparative laser processing system

[0035] 1.1 Structure

[0036] Figure 1 This is a diagram that schematically illustrates the structure of the comparative example laser processing system 10. The comparative examples disclosed herein are derived by analogy from general technical methods and are not known examples endorsed by the applicant.

[0037] The laser processing system 10 includes a laser device 12 and a laser processing apparatus 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 also be an excimer laser device. The wavelength of the pulsed laser light output by the laser device 12 may be, for example, above 158 nm and below 246 nm. Furthermore, a fluorine excimer laser device can output pulsed laser light with a wavelength of 158 nm.

[0038] The laser processing apparatus 14 includes a processing processor 100, high-reflectivity mirrors 111 and 112, an electrical scanner 120, a focusing lens 130, a stage 140, an XYZ stage 150, and a frame 154.

[0039] The high-reflectivity mirror 111 is configured to reflect the pulsed laser output from the laser device 12 and cause it to be incident on the high-reflectivity mirror 112. The high-reflectivity mirror 112 is configured to reflect the pulsed laser reflected by the high-reflectivity mirror 111 toward the electronic scanner 120.

[0040] The electrical scanner 120 includes an X-direction electrical scanner 121 that scans pulsed laser light in the X direction and a Y-direction electrical scanner 122 that scans pulsed laser light in the Y direction. The operation of the X-direction electrical scanner 121 and the Y-direction electrical scanner 122 is controlled in synchronization with the timing of the pulsed laser light from the output laser device 12. Figure 1 In this diagram, the direction parallel to the direction in which the pulsed laser travels from the focusing lens 130 toward the workpiece 20 is defined as the Z direction. Furthermore, the X and Y directions are defined as directions orthogonal to and mutually orthogonal to the Z direction. This will also be discussed in subsequent figures. Figure 1 Their coordinate axes are the same.

[0041] The condenser lens 130 focuses the pulsed laser light output from the electronic scanner 120. The condenser lens 130 can be any of a spherical lens, an aspherical lens, or an F-θ lens. The spot size of the focusing point can be, for example, around 200 μm to 300 μm.

[0042] The XYZ stage 150 is an actuator-equipped stage capable of moving in three mutually orthogonal axes: the X, Y, and Z directions. The XYZ stage 150 is fixed to the frame 154, and a platform 140 is mounted on the XYZ stage 150. The platform 140 is a mounting stage for placing the workpiece 20.

[0043] The workpiece 20 is positioned on the stage 140 at the focal point (focusing position) where the pulsed laser light is focused by the focusing lens 130. The workpiece 20 is a fluoropolymer, such as polytetrafluoroethylene (PTFE). The workpiece 20 is not limited to PTFE; it can also be perfluoroalkoxyalkane (PFA), perfluoroethylene-propylene copolymer (FEP), polyvinylidene fluoride (PVDF), etc.

[0044] The processing processor 100 controls the operation of the laser device 12, the electrical scanner 120, and the XYZ stage 150. The processing processor 100 may also be physically configured in hardware to execute the various processes included in this disclosure. For example, the processing processor 100 may be a computer including a memory storing control programs that define various processes, and a processing device for executing the control programs. The control programs may be stored in a single memory or separately in multiple physically separate memories, defining various processes through the control programs as a collection of these memories. 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).

[0045] Alternatively, the processing processor 100 can also be programmed in software to perform the various processes included in this disclosure. For example, the function of the processing processor 100 to perform various processes can be installed in a special-purpose device such as an ASIC (Application Specific Integrated Circuit) or a programmable device such as an FPGA (Field Programmable Gate Array).

[0046] The various processes included in this disclosure can be executed by a single computer, a single dedicated device, or a single programmable device, or by the cooperation of multiple physically separate computers, dedicated devices, or programmable devices. The various processes can also be executed by a combination of at least two of more than one computer, more than one dedicated device, and more than one programmable device.

[0047] 1.2 Actions

[0048] The pulsed laser output from the laser device 12 is reflected by high-reflectivity mirrors 111 and 112 and incident on the electronic scanner 120. The processing processor 100 moves the workpiece 20 via the XYZ stage 150 so that the position of the processing point on the workpiece 20 becomes the focal position. The focal position of the condenser lens 130 is near the surface of the workpiece 20. In addition, the Rayleigh length of the focal point selected by the condenser lens 130 is between 1 / 10 and 10 times the focal length relative to the thickness of the workpiece 20.

[0049] When machining holes in workpiece 20, the machining processor 100 instructs the electrical scanner 120 to use a pulsed laser to trace a closed track on the surface of workpiece 20 at a predetermined scanning speed. The closed track can be, for example, as shown in... Figure 2The image shown is a circular track, but it can also be an elliptical track or a long circle track composed of a combination of arcs and straight lines.

[0050] Figure 2 This is a diagram illustrating an example of the closed trajectory C of a pulsed laser on the surface of a workpiece 20 in a laser processing method based on a comparative example. Figure 2 The closed track C shown is a circular track with a diameter of D. Figure 3 This is an illustration showing the scattered light and heat generated when a pulsed laser is irradiated with a closed track C to perform hole machining on a workpiece 20.

[0051] The electrical scanner 120 receives instructions from the processing processor 100 to control the X-direction electrical scanner 121 and the Y-direction electrical scanner 122 so that the pulsed laser traces a circular path on the surface of the workpiece 20 at a specified scanning speed.

[0052] The processing processor 100, in coordination with the operation of the electrical scanner 120, outputs an On-Off control signal to the laser device 12 to control the output of pulsed laser light. The laser device 12 outputs pulsed laser light of a specified power according to the control signal. This irradiates the workpiece 20 with the pulsed laser light, performing hole machining. The processing processor 100 controls the electrical scanner 120 and the laser device 12 to make the pulsed laser light circle multiple times on the closed track C. Alternatively, approximately 40 pulses of laser light can be irradiated per revolution of the closed track C. After hole machining is completed, the processing processor 100 moves the workpiece 20 via the XYZ stage 150 so that the position irradiated by the pulsed laser becomes the position of the next machining point.

[0053] 1.3 Research Topic

[0054] Figure 4 This is a schematic diagram showing the cross-section of a hole processed by the laser processing method of the comparative example. The scattered light and heat generated by the pulsed laser irradiating the workpiece 20 process the workpiece 20 near the irradiated area. The result is as follows: Figure 4 As shown, when hole machining is performed using a closed track C, the diameter of the hole on the pulsed laser incident side (surface) is larger than the diameter of the hole on the opposite side (back side). That is, the machined hole produces a cone shape with a larger machining diameter on the pulsed laser incident side and a smaller machining diameter on the opposite side.

[0055] For example, if a hole is machined on a 2mm thick PTFE workpiece 20 with an input power of 8W, a scanning speed of 200mm / sec, a circular track diameter D of φ0.8mm, and 500 revolutions of the circular track, then the diameter of the hole on the surface side of the workpiece 20 will be φ1.6mm, and the diameter of the hole on the back side will be φ0.8mm. Furthermore, the input power refers to the power of the pulsed laser irradiating the workpiece 20.

[0056] In this case, regarding the machined hole, the region where the hole diameter varies in the thickness direction of the workpiece 20, from the edge of the hole on the surface side to the edge of the hole on the back side, is a tapered region T. The greater the difference between the hole diameter on the surface side and the hole diameter on the back side of the workpiece 20, the larger the tapered region T is.

[0057] In hole processing of fluoropolymers such as PTFE, it is required to process holes with a small tapered region T.

[0058] 2. Implementation Method 1

[0059] 2.1 Structure

[0060] Figure 5 This is a diagram that schematically illustrates the structure of a laser processing system including the laser processing apparatus 14A of Embodiment 1. Regarding... Figure 5 The structure shown illustrates the relationship with... Figure 1 The differences are as follows. The laser processing apparatus 14A of Embodiment 1 includes: a purging mechanism 170 for purging the light propagation section 126, which includes high-reflectivity mirrors 111, 112 and an electronic scanner 120, using an inactive gas; and a dust collection mechanism 180 for protecting the condenser lens 130. The high-reflectivity mirrors 111, 112 and the electronic scanner 120 are examples of the "optical system" in this disclosure.

[0061] The inactive gas used in the purging mechanism 170 can be nitrogen (N2). The N2 gas used for purging can be supplied from the output of the pulsed laser of the laser device 12, or it can be introduced from outside the laser processing device 14A, or both. A lens (not shown) disposed at the output of the pulsed laser can be used as a seal for the area being purged.

[0062] Figure 5 The purging mechanism 170 shown includes: a gas inlet 172 for introducing N2 gas from the outside into the housing 171 covering the area of ​​the light propagation section 126; and a gas outlet 173 for discharging N2 gas from the housing 171. The gas inlet 172 is located near the output section of the pulsed laser of the laser device 12, and the gas outlet 173 is located near the condenser lens 130. N2 gas supplied from at least one of the output section of the pulsed laser of the laser device 12 and the gas inlet 172 flows into the housing 171 towards the high-reflectivity mirrors 111 and 112, the electronic scanner 120, and the condenser lens 130, and is discharged from the gas outlet 173.

[0063] The dust collection mechanism 180 includes a dust collector 182 and a dust collection head 184. Figure 6This is a top view of the dust collection head 184. The dust collection head 184 has a central space 185 for guiding light. Two or more suction ports 187A and 187B are provided on an annular cover 186 that forms an air passage. The annular cover surrounds the space 185, which serves as the light guiding section. The suction ports 187A and 187B are connected to the dust collector 182 via pipes 188A and 188B, respectively.

[0064] The dust collection head 184 draws air through suction ports 187A and 187B, generating a spiral airflow. This airflow causes plumes and dust generated during processing to move outwards, thus suppressing the plumes and dust from obstructing the pulsed laser and reducing processing efficiency, as well as preventing plumes and dust from adhering to the focusing lens 130 and damaging the lens, thereby reducing transmittance.

[0065] Furthermore, through the generated airflow, the ozone produced by the incident pulsed laser also moves from the irradiation point of the pulsed laser to the outer periphery. Therefore, the pulsed laser is not absorbed by ozone, enabling efficient processing in an atmospheric environment. Other structures are the same as those in laser processing system 10.

[0066] 2.2 Actions

[0067] Figure 7 This diagram illustrates an example of the trajectory of a pulsed laser on the surface of a workpiece 20 based on the laser processing method of Embodiment 1. The laser processing method for machining a hole in the workpiece 20 using the laser processing apparatus 14A of Embodiment 1 includes the following steps: irradiating the workpiece 20 with a pulsed laser to create a pre-machined hole by drawing a first closed trajectory C1; and irradiating the workpiece 20 with the pre-machined hole with a pulsed laser to create the hole by drawing a second closed trajectory C2, wherein the second closed trajectory C2 is similar in shape to the first closed trajectory C1 but larger than the first closed trajectory C1. The second closed trajectory C2 may be a trajectory that conforms to the shape of the hole that is the processing target (purpose). "Conforms" is not limited to complete conformity but includes a practically permissible range, encompassing the concept of approximate conformity.

[0068] The process of machining a pre-machined hole is an example of the "first process" in this disclosure, and the process of machining a hole with a machining shape that is closer to the target hole than the pre-machined hole is an example of the "second process" in this disclosure. Furthermore, the control of machining the pre-machined hole is an example of the "first control" in this disclosure, and the control of machining a hole with a machining shape that is closer to the target hole than the pre-machined hole is an example of the "second control" in this disclosure. The laser processing method of Embodiment 1, including the first and second processes, is carried out in an atmospheric atmosphere without the use of an assist gas.

[0069] Figure 8 This is a cross-sectional view showing an example of a pre-machined hole obtained through the first process. Figure 9 This is a cross-sectional view showing an example of a hole obtained through the second process.

[0070] When performing hole machining on the workpiece 20 using the laser processing apparatus 14A of Embodiment 1, the processing processor 100 issues an instruction to the electrical scanner 120 to cause a pulsed laser to trace a first closed track C1 on the surface of the workpiece 20 at a predetermined scanning speed. The first closed track C1 may be, for example, […]. Figure 7 The circular track shown can also be an elliptical track or a long circle track.

[0071] The electrical scanner 120 receives instructions from the processing processor 100 to control the X-direction electrical scanner 121 and the Y-direction electrical scanner 122 to cause the pulsed laser to draw a first closed track C1 on the surface of the workpiece 20 at a specified scanning speed.

[0072] The processing processor 100, in conjunction with the operation of the electrical scanner 120, outputs an On-Off control signal to the laser device 12 to control the output of pulsed laser light. The laser device 12 outputs pulsed laser light of a specified power according to the control signal. This performs pre-machining of holes on the workpiece 20 (see reference). Figure 8 Pre-machined holes may not be through-holes, but through-holes are preferred. A through-hole is an example of a "through-hole" in this disclosure.

[0073] After that, as Figure 7 As shown, the processing processor 100 sends a command to the electrical scanner 120 to cause a pulsed laser to trace a second closed track C2 on the surface of the workpiece 20 at a predetermined scanning speed. The second closed track C2 can be a circular track, an elliptical track, or an oblong track.

[0074] When the first closed track C1 is a circular track with diameter D1, the second closed track C2 is a circular track with diameter D2, where diameter D2 is larger than diameter D1 (D1 < D2). Preferably, the center of the first closed track C1 coincides with the center of the second closed track C2. Figure 7 The diagram illustrates an example where the first closed orbit C1 and the second closed orbit C2 are concentric circles. Furthermore, the center of a closed orbit other than a circular orbit can be, for example, the centroid of a figure whose outline is the closed orbit. The distance between the first closed orbit C1 and the second closed orbit C2 is preferably constant over the entire circumference of the closed orbit.

[0075] Furthermore, the second closed track C2 is a closed track drawn inside the region where the thickness of the workpiece 20 changes due to the pre-machined hole being processed by the first closed track C1. That is, the region surrounded by the second closed track C2 is smaller than the region where the thickness of the workpiece 20 changes due to the processing by the first closed track C1, and is contained within the region where the thickness of the workpiece 20 changes due to the first process.

[0076] The electrical scanner 120 receives instructions from the processing processor 100 to control the X-direction electrical scanner 121 and the Y-direction electrical scanner 122 so that the pulsed laser traces the second closed track C2 on the surface of the workpiece 20 at a specified scanning speed.

[0077] The processing processor 100, in conjunction with the operation of the electrical scanner 120, outputs an On-Off control signal to the laser device 12 to control the output of pulsed laser light. The laser device 12 outputs pulsed laser light of a specified power according to the control signal. This performs hole machining.

[0078] After hole machining is completed, the machining processor 100 moves the workpiece 20 via the XYZ stage 150 so that the position irradiated by the pulsed laser becomes the position of the next machining point. The machining processor 100 is an example of a "processor" in this disclosure. The electrical scanner 120 and the XYZ stage 150 are examples of a "moving device" in this disclosure.

[0079] In addition, in the laser processing apparatus 14A of Embodiment 1, a process to thin the thickness can also be performed on a region smaller than the region where the thickness of the workpiece 20 changes due to laser irradiation with the second closed track C2 before processing by laser irradiation with the second closed track C2.

[0080] That is, between the step of machining the pre-machined hole with the first closed track C1 and the step of machining the hole of the target machining shape with the second closed track C2 after machining the pre-machined hole, a third closed track is added to irradiate the area with pulsed laser, further thinning the thickness of the area whose thickness changed during the machining of the pre-machined hole (first step). In this case, the third closed track can be larger than the first closed track C1 and smaller than the second closed track C2. Similarly, between the step of thinning the thickness with pulsed laser irradiation with the third closed track and the step of machining the target hole with the second closed track C2, a fourth closed track is added to irradiate the area with pulsed laser irradiation, further thinning the thickness of the area whose thickness changed due to laser irradiation with the first closed track C1 and the third closed track. In this case, the fourth closed track can be larger than the third closed track and smaller than the second closed track C2. In this way, the laser processing method of Embodiment 1 can also process the pre-machined hole while changing the size of the closed track in stages, and finally process the hole of the target machining shape.

[0081] 2.3 Functions and Effects

[0082] In the laser processing method of Embodiment 1, when the pre-processed hole is processed using the first closed track C1, the hole processing based on the second closed track C2 begins from a state where a portion of the workpiece 20 has been processed. Therefore, the processing time is shorter than in the case where processing is performed from the beginning using the second closed track C2.

[0083] Furthermore, in the case where pre-machined holes are pre-machined, the space in the area where the pre-machined holes are formed in the workpiece 20 is reduced. Therefore, the scattered light generated during hole machining with the second closed track C2 irradiates the inner surface of the hole less frequently compared to the case where machining is initially performed with the second closed track C2.

[0084] These effects suppress temperature rise in the area being machined. Furthermore, they suppress the amount of light processed by scattered light. As a result, it becomes possible to machine holes with a small tapered region T.

[0085] 2.4 Specific examples of hole machining

[0086] For example, for 2mm thick PTFE, after pre-machining a hole with an input power of 8W, a scanning speed of 400mm / sec, a diameter D1 of φ0.4mm as the first closed track C1, and a number of revolutions of 800, when machining a hole with an input power of 8W, a scanning speed of 400mm / sec, a diameter D2 of φ0.8mm as the second closed track C2, and a number of revolutions of 500, it is possible to machine a hole with a diameter of φ1.2mm on the surface of the PTFE irradiated by the pulsed laser and a diameter of φ0.8mm on the back side.

[0087] In the comparative example, the diameter of the hole processed by the laser processing method on the side irradiated by the pulsed laser is φ1.6 mm, but in the laser processing method of Embodiment 1, it becomes smaller to φ1.2 mm. Therefore, in Embodiment 1, in the processing of PTFE holes by irradiating with a pulsed laser of ultraviolet wavelength, it is possible to perform laser processing of holes with a smaller tapered region T.

[0088] Furthermore, in the specific examples described above, the laser processing method of Embodiment 1 improves the scanning speed compared to the laser processing method of the comparative example, performing processing at twice the scanning speed (400 mm / sec) compared to the scanning speed (200 mm / sec) of the comparative example. Therefore, the processing time based on the laser processing method of Embodiment 1 can be approximately the same as or shorter than the processing time based on the laser processing method of the comparative example.

[0089] In addition, in the laser processing apparatus 14A of Embodiment 1, pulsed laser is irradiated onto the workpiece 20 from one direction, and pre-processed holes and subsequent holes are processed continuously. The next hole is processed after one hole is processed. Therefore, it is not necessary to flip the surface of the workpiece 20, which can shorten the processing time.

[0090] Furthermore, the laser processing method of Embodiment 1 can shorten the processing time, thus having the effect of suppressing the thermal effects generated on the PTFE, which is the workpiece 20, during processing.

[0091] 2.5 Regarding processing conditions

[0092] [1] Scanning speed

[0093] The scanning speeds for depicting the first closed track C1 and the second closed track C2 can be appropriately determined based on the thickness of the workpiece 20, the power of the pulsed laser, the machining shape of the target hole, and the size of the allowable tapered region T. The scanning speeds for depicting the first closed track C1 and the second closed track C2 can be equal or different. For the first closed track C1, a scanning speed of 400 mm / sec and 800 revolutions are examples of conditions experimentally determined to enable machining of a through hole as a pre-machined hole. Similarly, for the second closed track C2, a scanning speed of 400 mm / sec and 500 revolutions are examples of conditions experimentally determined to enable machining of the target hole.

[0094] [2] Number of orbits of a closed orbit

[0095] The number of times to circle along the first closed track C1 when machining the pre-machined hole and the number of times to circle along the second closed track C2 after machining the pre-machined hole can be appropriately determined based on the thickness of the workpiece 20, the power of the pulsed laser, the machining shape of the target hole, the size of the allowable tapered region T, etc.

[0096] The number of times the first closed orbit C1 and the number of times the second closed orbit C2 are wound can each be multiple. For example, the number of times the second closed orbit C2 is wound can be fewer than the number of times the first closed orbit C1 is wound.

[0097] 2.6 Examples of applications for machining workpieces with holes

[0098] The workpiece 20 with holes can be used, for example, in Braille devices. Braille devices, for example, have holes approximately 50 cm in diameter. 2 Approximately 100 holes are needed densely packed on a PTFE sheet of a certain area. Multiple holes can be processed on the PTFE sheet using the laser processing apparatus 14A of Embodiment 1. The laser processing method of Embodiment 1 allows for the processing of multiple holes where the distance between adjacent holes is, for example, 0.1 mm or more and 3.0 mm or less.

[0099] 3. Other

[0100] The foregoing description is not limiting but merely illustrative. 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. Furthermore, combinations of embodiments of this disclosure will also be apparent to those skilled in the art.

[0101] Unless otherwise expressly stated, the terms used throughout this specification and the claims shall be interpreted as “non-restrictive” terms. For example, terms such as “comprising,” “having,” “possessing,” and “complementing” shall be interpreted as “not excluding the presence of constituent elements other than those described.” Furthermore, the modifier “a” shall be interpreted as meaning “at least one” or “one or more.” Additionally, the term “at least one of A, B, and C” shall be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C.” Moreover, it shall be interpreted as also including combinations of them other than “A,” “B,” and “C.”

Claims

1. A laser processing method, comprising the following steps: The first step involves processing a pre-machined hole by irradiating the fluororesin with a pulsed laser of ultraviolet wavelength in a manner that traces a first closed trajectory; and In the second step, the fluororesin with the pre-processed hole is irradiated with the pulsed laser to process the hole in a manner that draws a second closed track. The second closed track is similar in shape to the first closed track but is larger than the first closed track.

2. The laser processing method according to claim 1, wherein, The second closed track is contained in the region where the thickness of the fluoropolymer has changed due to the first process.

3. The laser processing method according to claim 1, wherein, The ultraviolet wavelength is above 158nm and below 246nm.

4. The laser processing method according to claim 1, wherein, The pre-machined hole is a through hole.

5. The laser processing method according to claim 1, wherein, The first closed track is a circular track.

6. The laser processing method according to claim 1, wherein, The first and second processes are carried out in an atmospheric atmosphere without the use of auxiliary gases.

7. The laser processing method according to claim 1, wherein, The second closed track is consistent with the shape of the hole that is the processing target.

8. The laser processing method according to claim 1, wherein, The hole is processed by irradiating the pulsed laser in a manner that traces the second closed track inside the region where the thickness of the fluororesin has changed due to the first process.

9. The laser processing method according to claim 1, wherein, The center of the first closed track coincides with the center of the second closed track.

10. The laser processing method according to claim 1, wherein, The first step includes the following steps: irradiating the fluororesin with the pulsed laser in a manner that repeatedly traces the first closed trajectory. The second step includes the following step: irradiating the fluororesin with the pulsed laser in a manner that draws the second closed track multiple times.

11. The laser processing method according to claim 10, wherein, The number of times it circles along the second closed orbit is less than the number of times it circles along the first closed orbit.

12. The laser processing method according to claim 1, wherein, The scanning speed of the first closed track is equal to the scanning speed of the second closed track.

13. A laser processing apparatus, comprising: A focusing lens that focuses a pulsed laser beam of ultraviolet wavelength onto the fluororesin being processed; A moving device that moves the position where the pulsed laser irradiates the fluororesin; as well as The processor controls the mobile device. The processor executes: The first control involves irradiating the fluororesin with the pulsed laser in a manner that traces a first closed trajectory to process a pre-machined hole; as well as The second control involves irradiating the fluororesin with the pre-processed hole using the pulsed laser to process the hole in a manner that draws a second closed track. The second closed track is similar in shape to the first closed track but is larger than the first closed track.

14. The laser processing apparatus according to claim 13, wherein, The laser processing device also has a dust collection mechanism to protect the focusing lens.

15. The laser processing apparatus according to claim 14, wherein, The dust collection mechanism includes: The dust collection head generates a spiral airflow; and A dust collector, which is connected to the dust collection head.

16. The laser processing apparatus according to claim 13, wherein, The laser processing apparatus also includes a purging mechanism that allows inactive gas to flow in a light propagation section, which includes an optical system that guides the pulsed laser to the focusing lens.

17. The laser processing apparatus according to claim 13, wherein, The processor controls the moving device to draw the second closed track inside the region where the thickness of the fluoropolymer resin changes due to the first control.

18. The laser processing apparatus according to claim 13, wherein, The ultraviolet wavelength is above 158nm and below 246nm.

19. The laser processing apparatus according to claim 13, wherein, The pre-machined hole is a through hole.

20. The laser processing apparatus according to claim 13, wherein, The first closed orbit and the second closed orbit are concentric circles.

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